The patellar clunk syndrome describes painful catching, grinding or jumping of the patella when the knee moves from a flexed to an extended position after total knee replacement (TKR). The posterior stabilised TKR had been noted to have a higher incidence of this problem. Mobile-bearing posteriorly stabilised TKRs have been introduced to improve patellar tracking and related problems by a mechanism of self-alignment. We evaluated the patellar clunk syndrome in 113 knees in 93 patients with such a TKR at a mean follow-up of 2.3 years (2.0 to 3.2). The syndrome was identified in 15 knees (13.3%). Logistic regression analysis showed that the absolute value of the post-operative angle of patellar tilt was significantly associated with the occurrence of patellar clunk (p = 0.025). Patellar tracking should be carefully checked during surgery

The Bisurface knee prosthesis (BP) has a posterior stabilising cam (ball-and-socket joint) in the mid-posterior region of the femorotibial joint in an attempt to improve the range of movement. Based on an in vitro weight-bearing study contact areas of the Insall/Burstein 2 (IB2) and the BP knee were compared using pressure-sensitive films. The stability afforded by the cam was evaluated by means of dislocation distances in the vertical and horizontal planes. Significant adverse anterior translation in mid-flexion was not observed with the BP knee since the cam was effective above 60° of flexion. At flexion of 60° or more, the total contact areas were larger, as the cam represented a weight-bearing surface. The dislocation distances for the BP knee compared favourably with those for the IB2 knee. We conclude that the cam of the BP knee allows good movement, stability and wear

We present a prospective study of patients with tuberculosis of the dorsal, dorsolumbar and lumbar spine after combined anterior (radical debridement and anterior fusion) and posterior (instrumentation and fusion) surgery. The object was to study the progress of interbody union, the extent of correction of the kyphosis and its maintenance with early mobilisation, and the incidence of graft and implant-related problems. The American Spinal Injury Association (ASIA) score was used to assess the neurological status. The mean preoperative vertebral loss was highest (0.96) in the dorsal spine. The maximum correction of the kyphosis in the dorsolumbar spine was 17.8°. Loss of correction was maximal in the lumbosacral spine at 13.7°. All patients had firm anterior fusion at a mean of five months. The incidence of infection was 3.9% and of graft-related problems 6.5%. We conclude that adjuvant posterior stabilisation allows early mobilisation and rehabilitation. Graft-related problems were fewer and the progression and maintenance of correction of the kyphosis were better than with anterior surgery alone. There is no additional risk relating to the use of an implant either posteriorly or anteriorly even when large quantities of pus are present

Abstract. Introduction. Total knee replacement (TKR) in patients with skeletal dysplasia is technically challenging surgery due to deformity, joint contracture, and associated co-morbidities. The aim of this study is to follow up patients with skeletal dysplasia following a TKR. Methodology. We retrospectively reviewed 22 patients with skeletal dysplasia who underwent 31 TKRs at our institution between 2006 and 2022. Clinical notes, operative records and radiographic data were reviewed. Results. Achondroplasia was the most common skeletal dysplasia (8), followed by Chondrodysplasia punctata (7) and Spondyloepiphyseal dysplasia (5). There were fourteen men and eight women with mean age of 51 years (28 to 73). The average height of patients was 1.4 metres (1.16–1.75) and the mean weight was 64.8 Kg (34.3–100). The mean follow up duration was 68.32 months (1–161). Three patients died during follow up. Custom implants were required in twelve patients (38.71%). Custom jigs were utilised in six patients and two patients underwent robotic assisted surgery. Hinged TKR was used in seventeen patients (54.84%), posterior stabilised TKR in nine patients (29.03%), and cruciate retaining TKR in five patients (16.13%). One patient underwent a patella resurfacing for persistent anterior knee pain and another had an intra-operative medial tibial plateau fracture which was managed with fixation. No revisions occurred during the follow up period. Conclusion. Despite the technical challenges and complexity of TKR within this unique patient group, we demonstrate good implant survivorship during the study period. Cross sectional imaging is recommended preoperatively for precise planning and templating

Numerous papers present in-vivo knee kinematics data following total knee arthroplasty (TKA) from fluoroscopic testing. Comparing data is challenging given the large number of factors that potentially affect the reported kinematics. This paper aims at understanding the effect of following three different factors: implant geometry, performed activity and analysis method. A total of 30 patients who underwent TKA were included in this study. This group was subdivided in three equal groups: each group receiving a different type of posterior stabilized total knee prosthesis. During single-plane fluoroscopic analysis, each patient performed three activities: open chain flexion extension, closed chain squatting and chair-rising. The 2D fluoroscopic data were subsequently converted to 3D implant positions and used to evaluate the tibiofemoral contact points and landmark-based kinematic parameters. Significantly different anteroposterior translations and internal-external rotations were observed between the considered implants. In the lateral compartment, these differences only appeared after post-cam engagement. Comparing the activities, a significant more posterior position was observed for both the medial and lateral compartment in the closed chain activities during mid-flexion. A strong and significant correlation was found between the contact-points and landmarks-based analyses method. However, large individual variations were also observed, yielding a difference of up to 25% in anteroposterior position between both methods. In conclusion, all three evaluated factors significantly affect the obtained tibiofemoral kinematics. The individual implant design significantly affects the anteroposterior tibiofemoral position, internal-external rotation and timing of post-cam engagement. Both kinematics and post-cam engagement additionally depend on the activity investigated, with a more posterior position and associated higher patella lever arm for the closed chain activities. Attention should also be paid to the considered analysis method and associated kinematics definition: analyzing the tibiofemoral contact points potentially yields significantly different results compared to a landmark-based approach

Total knee replacement (TKR) design aims to restore normal kinematics with emphasis on flexion range. The survivorship of a TKR is dependent on the kinematics in six-degrees-of-freedom (6-DoF). Stepping up, such as stair ascent is a kinematically demanding activity after TKR. The debate about design choice has not yet been informed by 6-DoF in vivo kinematics. This prospective randomised controlled trial (RCT) compared kneeling kinematics in three TKR designs. 68 participants were randomised to receive either cruciate retaining (CR-FB), rotating platform (CR-RP) or posterior stabilised (PS-FB) prostheses. Image quality was sufficient for 49 of these patients to be included in the final analysis following a minimum 1-year follow-up. Patients completed a step-up task while being imaged using single-plane fluoroscopy. Femoral and tibial computer-aided design (CAD) models for each of the TKR designs were registered to the fluoroscopic images using bespoke software OrthoVis to generate six-degree-of-freedom kinematics. Differences in kinematics between designs were compared as a function of flexion. There were no differences in terminal extension between the groups. The CR-FB was further posterior and the CR-RP was more externally rotated at terminal extension compared to the other designs. Furthermore, the CR-FB designs was more posteriorly positioned at each flexion angle compared to both other designs. Additionally, the CR-RP design had more external femoral rotation throughout flexion when compared with both fixed bearing designs. However, there were no differences in total rotation for either step-up or down. Visually, it appears there was substantial variability between participants in each group, indicating unique patient-specific movement patterns. While use of a specific implant design does influence some kinematic parameters, the overall patterns are similar. Furthermore, there is high variability indicating patient-specific kinematic patterns. At a group level, none of these designs appear to provide markedly different step-up kinematic patterns. This is important for patient expectations following surgery. Future work should aim to better understand the unique patient variability

Stand-alone anterior lumbar interbody fusion (ALIF) provides the opportunity to avoid supplemental posterior fixation. This may reduce morbidity and complication rate, which is of special interest in patients with reduced bone mineral density (BMD). This study aims to assess immediate biomechanical stability and radiographic outcome of a stand-alone ALIF device with integrated screws in specimens of low BMD. Eight human cadaveric spines (L4-sacrum) were instrumented with SynFix-LR™ (DePuy Synthes) at L5/S1. Quantitative computed tomography was used to measure BMD of L5 in AMIRA. Threshold values proposed by the American Society of Radiology 80 and 120 mg CaHa/mL were used to differentiate between Osteoporosis, Osteopenia, and normal BMD. Segmental lordosis, anterior and posterior disc height were analysed on pre- and postoperative radiographs (Fig 1). Specimens were tested intact and following instrumentation using a flexibility protocol consisting of three loading cycles to ±7.5 Nm in flexion-extension, lateral bending, and axial rotation. The ranges of motion (ROM) of the index level were assessed using an optoelectronic system. BMD ranged 58–181mg CaHA/mL. Comparison of pre- and postoperative radiographs revealed significant increase of L5/S1 segmental lordosis (mean 14.6°, SD 5.1, p < 0.001) and anterior disc height (mean 5.8mm, SD 1.8, p < 0.001), but not posterior disc height. ROM of 6 specimens was reduced compared to the intact state. Two specimens showed destructive failure in extension. Mean decrease was most distinct in axial rotation up to 83% followed by flexion-extension. ALIF device with integrated screws at L5/S1 significantly increases segmental lordosis and anterior disc height without correlation to BMD. Primary stability in the immediate postoperative situation is mostly warranted in axial rotation. The risk of failure might be increased in extension for some patients with reduced lumbar BMD, therefore additional posterior stabilization could be considered. For any figures or tables, please contact the authors directly

Constrained implants with intra-medullary fixation are expedient for complex TKA. Constraint is associated with loosening, but can correction of deformity mitigate risk of loosening?. Primary TKA's with a non-linked constrained prosthesis from 2010-2018 were identified. Indications were ligamentous instability or intra-medullary fixation to bypass stress risers. All included fully cemented 30mm stem extensions on tibia and femur. If soft tissue stability was achieved, a posterior stabilized (PS) tibial insert was selected. Pre and post TKA full length radiographs showed. i. hip-knee-ankle angles (HKAA). ii. Kennedy Zone (KZ) where hip to ankle vector crosses knee joint. 77 TKA's in 68 patients, average age 69.3 years (41-89.5) with OA (65%) post-trauma (24.5%) and inflammatory arthropathy (10.5%). Pre-op radiographs (62 knees) showed varus in 37.0%. (HKAA: 4. o. -29. o. ), valgus in 59.6% (HKAA range 8. o. -41. o. ) and 2 knees in neutral. 13 cases deceased within 2 years were excluded. Six with 2 year follow up pending have not been revised. Mean follow-up is 6.1 yrs (2.4-11.9yrs). Long post-op radiographs showed 34 (57.6%) in central KZ (HKKA 180. o. +/- 2. o. ). . Thirteen (22.0%) were in mechanical varus (HKAA 3. o. -15. o. ) and 12 (20.3%) in mechanical valgus: HKAA (171. o. -178. o. ). Three failed with infection; 2 after ORIF and one with BMI>50. The greatest post op varus suffered peri-prosthetic fracture. There was no aseptic loosening or instability. Only full-length radiographs accurately measure alignment and very few similar studies exist. No cases failed by loosening or instability, but PPF followed persistent malalignment. Infection complicated prior ORIF and elevated BMI. This does not endorse indiscriminate use of mechanically constrained knee prostheses. Lower demand patients with complex arthropathy, especially severe deformity, benefit from fully cemented, non-linked constrained prostheses, with intra-medullary fixation. Hinges are not necessarily indicated, and rotational constraint does not lead to loosening

Most studies comparing medial pivot to the posterior stabilised (PS) systems sacrifice the PCL. It is unknown whether retaining the PCL in the Medial Congruent (MC) system may provide further benefit compared to the more commonly used PS system. A retrospective review of a single-surgeon's registry data comparing 44 PS and 25 MC with PCL retained (MC-PCLR) TKAs was performed. Both groups had similar baseline demographics in terms of age, gender, body mass index, and American Society for Anaesthesiology score. There was no significant difference in their preoperative range of motion (ROM) (104º±20º vs. 102º±20º,p=0.80), Oxford Knee Score (OKS) (27±6 vs. 26±7,p=0.72), and Knee Society Scoring System (KS) Function Score (KS-FS) (52±24 vs. 56±24,p=0.62). The preoperative KS Knee Score (KS-KS) was significantly lower in the PS group (44±14 vs. 54 ± 18,p<0.05). At 3-months postoperation, the PS group had significantly better OKS (38±6 vs. 36±6,p=0.02) but similar ROM (111º±14º vs. 108º±12º,p=0.25), KS-FS (73±20 vs. 68±23, p=0.32) and KS-KS (87±10 vs. 86±9,p=0.26). At 12-months postoperation, both groups had similar ROM (115º±13º vs. 115º±11º,p=0.99), OKS (41±5 vs. 40±5,p=0.45), KS-FS (74±22vs.78±17,p=0.80), and KS-KS (89±10vs.89±11,p=0.75). There was statistically significant improvement in all parameters at 1-year postoperation (p<0.05). The PS group had significant improvement in all parameters from preoperation to 3-month postoperation (p<0.05), but not from 3-month to 1-year postoperation (p≥0.05). The MC-PCLR group continued to have significant improvement from 3-month to 1-year postoperation (p<0.05). The MC provides stability in the medial compartment while allowing a degree of freedom in the lateral compartment. Preserving the PCL when using MC may paradoxically cause an undesired additional restrain that slows the recovery process of the patients after TKA. In conclusion, compared to MC-PCLR, a PS TKA may expect significantly faster improvement at 3 months post operation, although they will achieve similar outcomes at 1-year post operation

Aims. Modern total knee arthroplasty (TKA) prostheses are designed to restore near normal kinematics including high flexion. Kneeling is a high flexion, kinematically demanding activity after TKA. The debate about design choice has not yet been informed by six-degrees-of-freedom in vivo kinematics. This prospective randomized clinical trial compared kneeling kinematics in three TKA designs. Methods. In total, 68 patients were randomized to either a posterior stabilized (PS-FB), cruciate-retaining (CR-FB), or rotating platform (CR-RP) design. Of these patients, 64 completed a minimum one year follow-up. Patients completed full-flexion kneeling while being imaged using single-plane fluoroscopy. Kinematics were calculated by registering the 3D implant models onto 2D-dynamic fluoroscopic images and exported for analysis. Results. CR-FB designs had significantly lower maximal flexion (mean 116° (SD 2.1°)) compared to CR-RP (123° (SD 1.6°)) and PS-FB (125° (SD 2.1°)). The PS-FB design displayed a more posteriorly positioned femur throughout flexion. Furthermore, the CR-RP femur was more externally rotated throughout kneeling. Finally, individual patient kinematics showed high degrees of variability within all designs. Conclusion. The increased maximal flexion found in the PS-FB and CR-RP designs were likely achieved in different ways. The PS-FB design uses a cam-post to hold the femur more posteriorly preventing posterior impingement. The external rotation within the CR-RP design was surprising and hasn’t previously been reported. It is likely due to the polyethylene bearing being decoupled from flexion. The findings of this study provide insights into the function of different knee arthroplasty designs in the context during deep kneeling and provide clinicians with a more kinematically informed choice for implant selection and may allow improved management of patients' functional expectations. Cite this article: Bone Joint J 2021;103-B(1):105–112

Background. The purpose of this study was to evaluate the clinical and radiographic outcomes of the rotating-platform, posterior-stabilized PFC Sigma at fifteen-year follow-up. Methods. Between January 2000 and November 2001, two hundred consecutive patients underwent TKA with a rotating-platform, posterior stabilized total knee arthroplasty with cement. All patients have been followed prospectively and all patients with minimum 12 year follow up were included in this analysis. Forty-nine TKAs were available for our final analysis with a mean follow up of 16.0 years. Results. The improvements in Knee Society pain and function scores were 44 to 83. The 15-year Koos Jr interval scores for cohort was 76.2. The range of motion improved from 111° to 115°. The prevalence of residual pain was 32.5%, painless crepitation was 15% and 5% reporting painful crepitation at 15-year follow up via PROMs. Kaplan-Meier analysis revealed that the survivorship was 100% due to mechanical failure as an endpoint, and 95% as reoperation as an end-point. Conclusions. At fifteen-year follow up, the rotating-platform, posterior stabilized arthroplasty demonstrated excellent survivorship and radiographic results. Peripatellar crepitation, occasionally requiring excision, remains an issue. For figures, tables, or references, please contact authors directly

Introduction and Objective. Gait variability is the amplitude of the fluctuations in the time series with respect to the mean of kinematic (e.g., joint angles) or kinetic (e.g., joint moments) measurements. Although gait variability increases with normal ageing or pathological mechanisms, such as knee osteoarthritis (OA). The purpose was to determine if a patient who underwent a total knee arthroplasty (TKA) can reduce gait variability. Materials and Methods. Twenty-five patients awaiting TKA were randomly assigned to receive either medial pivot (MP, m=7/f=6, age=62.4±6.2 years) or posterior stabilized (PS, m=7/f=5, age=63.7±8.9 years) implants, and were compared to 13 controls (CTRL, m=7/f=6, age=63.9±4.3 years). All patients completed a gait analysis within one month prior and 12 months following surgery, CTRLs completed the protocol once. A waveform F-Test Method (WFM) was used to compare the variance in knee biomechanics variables at each interval of the gait cycle. Results. Preoperatively, the PS group had greater sagittal knee angle variability compared to the MP (32–58% gait cycle) and CTRL (21–53% gait cycle) groups. Postoperatively, no difference in sagittal knee angle variability existed between any of the groups. Preoperatively, sagittal knee moment variability was greater in the MP (2–39% gait cycle) and PS (5–19% and 42–57% gait cycle) groups compared to the CTRL. Postoperatively, sagittal knee moment was lower in the MP (49–55% gait cycle) and greater in the PS (23–36% gait cycle) compared to the CTRL. Knee power variability was greater preoperatively in the MP (52–61% gait cycle) and PS (52–62% gait cycle) compared to the CTRL. Postoperatively, knee power variability was lower in the MP (17–22% and 45–50% gait cycle) and PS (6–23%, 34–41% and 45–49% gait cycle) compared to the CTRL group. Conclusions. Preoperatively, knee OA patients have greater variability in knee moments than CTRLs during the transition from double-limb support to single-limb support on the affected limb. This indicates knee instability as patients are adopting a gait strategy that refers to knee muscle contraction avoidance. The MP group showed greater knee stability postoperatively as they had lower knee moment and power variability compared to the CTRL. The significance of having less variability than CTRLs is not well understood at this time. Future research on muscle activity is needed to determine if neuromuscular adaptations are causing these reductions in variability after TKA

Aims. To compare patients undergoing total knee arthroplasty (TKA) with ≤ 80° range of movement (ROM) operated with a 2 mm increase in the flexion gap with matched non-stiff patients with at least 100° of preoperative ROM and balanced flexion and extension gaps. Methods. In a retrospective cohort study, 98 TKAs (91 patients) with a preoperative ROM of ≤ 80° were examined. Mean follow-up time was 53 months (24 to 112). All TKAs in stiff knees were performed with a 2 mm increased flexion gap. Data were compared to a matched control group of 98 TKAs (86 patients) with a mean follow-up of 43 months (24 to 89). Knees in the control group had a preoperative ROM of at least 100° and balanced flexion and extension gaps. In all stiff and non-stiff knees posterior stabilized (PS) TKAs with patellar resurfacing in combination with adequate soft tissue balancing were used. Results. Overall mean ROM in stiff knees increased preoperatively from 67° (0° to 80°) to 114° postoperatively (65° to 135°) (p < 0.001). Mean knee flexion improved from 82° (0° to 110°) to 115° (65° to 135°) and mean flexion contracture decreased from 14° (0° to 50°) to 1° (0° to 10°) (p < 0.001). The mean Knee Society Score (KSS) improved from 34 (0 to 71) to 88 (38 to 100) (p < 0.001) and the KSS Functional Score from 43 (0 to 70) to 86 (0 to 100). Seven knees (7%) required manipulations under anaesthesia (MUA) and none of the knees had flexion instability. The mean overall ROM in the control group improved from 117° (100° to 140°) to 123° (100° to 130°) (p < 0.001). Mean knee flexion improved from 119° (100° to 140°) to 123° (100° to 130°) (p < 0.001) and mean flexion contracture decreased from 2° (0° to 15°) to 0° (0° to 5°) (p < 0.001). None of the knees in the control group had flexion instability or required MUA. The mean KSS Knee Score improved from 48 (0 to 80) to 94 (79 to 100) (p < 0.001) and the KSS Functional Score from 52 (5 to 100) to 95 (60 to 100) (p < 0.001). Mean improvement in ROM (p < 0.001) and KSS Knee Score (p = 0.017) were greater in knees with preoperative stiffness compared with the control group, but the KSS Functional Score improvement was comparable (p = 0.885). Conclusion. TKA with a 2 mm increased flexion gap provided a significant improvement of ROM in knees with preoperative stiffness. While the improvement in ROM was greater, the absolute postoperative ROM was less than in matched non-stiff knees. PS TKA with patellar resurfacing and a 2 mm increased flexion gap, in combination with adequate soft tissue balancing, provides excellent ROM and knee function when stiffness of the knee had been present preoperatively. Cite this article: Bone Joint J 2020;102-B(4):426–433

Purpose. The success of total knee replacement (TKR) surgery can be attributed to improvements in TKR design, instrumentation, and surgical technique. Over a decade ago oxidized zirconium (OxZr) femoral components were introduced as an alternative bearing surface to cobalt-chromium (CoCr), based on strong in-vitro evidence, to improve the longevity of TKR implants. Early reports have demonstrated the clinical success of this material however no long-term comparative studies have demonstrated the superiority of OxZr implants compared to a more traditional CoCr implant. This study aims to compare long-term survivorship and outcomes in OxZr and CoCr femoral components in a single total knee design. Methods. We reviewed our institutional database to identify all patients whom underwent a TKA with a posterior stabilized OxZr femoral component with a minimum of 10 years of follow-up. These were then matched to patients whom underwent a TKA with the identical design posterior stabilized CoCr femoral component during the same time period by gender, age and BMI. All patients had their patella resurfaced. All patients were prospectively evaluated preoperatively and postoperatively at 6 weeks, 3 months, 12 months, 2 years and every 1 to 2 years thereafter. Prospectively collected clinical outcome measures included, Western Ontario and McMaster Universities osteoarthritis index (WOMAC), Short-Form 12 (SF-12) and Knee Society clinical rating scores (KSCRS). Charts and radiographs were reviewed to determine the revision rates and survivorship (both all cause and aseptic) at 10 years allowing comparison between the two cohorts. Paired analysis was performed to determine if differences existed in patient reported outcomes. Results. There were 194 OxZr TKAs identified and matched to 194 CoCr TKAs. There was no difference in average age (OxZr, 54.2 years; CoCr, 54.4 years), Gender (OxZr, 61.9% female; CoCr, 61.9% female) and average body mass index (OxZr, 35.9 kg/m2; CoCr, 36.4 kg/m2) between the two cohorts. There were no significant differences preoperatively in any of the outcome scores between the two groups (WOMAC (p=0.361), SF-12 (p=0.771) and KSCRS (p=0.161)). Both the SF12 (p=0.787) and WOMAC (p=0.454) were similar between the two groups, however the OxZr TKA cohort had superior KSCRS compared to the CoCr TKA cohort at a minimum of 10 years (173.5 vs. 159.1, p=0.002). With revision for any reason as the end point, there was no significant difference in 10-year survivorship between the two groups (OxZr and CoCr, 96.4%, p=0.898). Similarly, aseptic revisions demonstrated comparable survivorship rates at 10-year between the OxZr (98.9%) and CoCr groups (97.9%) (p=0.404). Conclusion. In this matched cohort study, both groups demonstrated similar improvements in patient reported outcomes, although the OxZr cohort had greater KSCRS scores compared to the CoCr cohort. The reason for this difference is not clear but may represent selection bias, where OxZr implants were perhaps used in more active patients. Implant survivorship, based on revision rates for all causes and/or aseptic reasons, was excellent and similar for both the OxZr and CoCr femoral components at 10 years. Therefore, with respect to implant longevity at the end of the first decade, there appears to be no clear advantage of OxZr compared to CoCr for patients with similar demographics with this specific posterior stabilized TKA design. Further follow-up into the second and third decade may be required to demonstrate if a difference does exist

Knee flexion is often decreased in severe arthritis causing pain, and functional limitations in lifestyles and occupations. Newer knee replacement designs offer the possibility of greater knee motion. The objective of our study was to compare the clinical outcomes, in particular the range of motion, in patients treated with a total knee arthroplasty using either a standard posterior stabilized knee prosthesis or a high flexion posterior stabilized knee prosthesis, with regard to return to function within 1 year of surgery. This was a prospective randomized single blinded study. Forty patients were randomly assigned to receive either a standard fixed bearing posterior stabilized or a modified high flexion fixed bearing posterior stabilized Smith & Nephew Genesis II total knee joint replacement. Clinical outcomes were determined from data collected on all patients who were evaluated pre-operatively, at twelve weeks post-operatively, and at one year post-operatively. Data collected included SF-12, WOMAC, and Oxford knee scores, and knee range of motion measurements. 37 of 40 patients enrolled completed the study. 22 patients were randomized to receive a standard posterior stabilized fixed bearing Genesis II knee replacement and 22 were randomized to receive a Hi-Flex posterior stabilized fixed bearing knee replacement. ROM, quality of life, and clinical scores at 12 months will be presented

The purpose of this study was to evaluate the effect of decreasing tibial slope on extention gap during posterior stabilized total knee arthroplasty. 110 posterior stabilized total knee arthroplasties were studied for 2 groups;. having flexion contractures(n=35),. having no flexion contracture(n=75). In each group, we measured the decrease of tibial slope and frequency of additional distal femoral resecions that were done due to insufficient extension gap in comparison with flexion gap during posterior stabilized total knee arthroplasty. We also compared frequencies of additional distal femoral resections between 2 parts having more and less slope decrease in each groups. In each group, tibial slope decrease were 8.7 degrees, 7.4 degrees(p=0.145) and frequencies of additional resection were 51.4%, 24%(p=0.005) in average. In 2 parts having more and less slope decrease in each group, frequencies of additional resection were 44.4% vs 58.8%(p=0.505), 13.2% vs 35.1%(p=0.032). Results suggested that more decrease of tibial slope reduced frequency of additional distal femoral resection during posterior stabilized total knee arthroplasty in group having no flexion contracture. Decreasing tibial slope can be considered as a factor influencing on extension gap during posterior stabilized total knee arthroplasty. The estimation of predictable tibia slope decrease through preoperative radiologic findings can be beneficial in performing succeful posterior stabilized total knee arthroplasty

Introduction. Increasingly young and active patients are concerned about revision arthroplasty forcing the manufacturers to think about revision prostheses that fit to this population while meeting the indications and fitting with bone losses and ligament deficiencies. One of those industrials claims that its system allows the surgeon to rise the constraint from a posterior stabilized (PS) prostheses to a semi-constraint total stabilized (TS) prostheses without modifying the gait pattern thanks to a similar single radius design. The aim of the study was to compare gait parameters in patients receiving either PS or TS knee prostheses. Methods. Nineteen patients in each groups were prospectively collected for this study and compared between each other. All subjects were assessed with a 3D knee kinematics analysis, performed with an optoelectronic knee assessment device (KneeKG®). Were measured for each knees range of motion (ROM) in flexion–extension, abduction–adduction, internal–external rotation and anterior–posterior displacement. Results. There were no significant kinematic differences between PS and TS groups. The ROM in flexion-extension was 44° in PS group vs 46° in TS group, the ROM in internal-external rotation was 5.5° in PS group vs 4°in TS group. Peak varus angle during loading was equal (2.5°) and higher in PS group during swing phases (5.5° vs 3.7°) without any significancy. There appeared to be less antero-posterior translation in the TS group (maximum posterior displacement of −1 mm vs −5 mm) linked to the larger central post-cam without any significancy. Conclusion. TS designed have comparable gait parameters than PS prostheses. Its use won't prejudice the patient concerning the walking pattern

Object. Although single-radius designs have theoretical advantages in some aspects, there has been a paucity of evaluation studies. The purpose of this study was to compare 10-year clinical, radiological, survivorship outcomes of single radius and multi radius posterior stabilized prosthesis in total knee arthroplasty(TKA) with Rheumatoid Arthritis (RA). Method. In this retrospective observational study, we reviewed 240 patients (240 knees) with RA who underwent TKA between Oct 2005 and Dec 2007: SR group (120 patients, 120 knees, Stryker Scorpio NRG) and MR group (120 patients, 120 knees, Depuy sigma RP). A 1 : 1 matched case control study was conducted in two groups which were similar in terms of age, gender, BMI, ASA classification and operation team. Mean follow-up periods were 10.73±1.13 (range: 8–13) years and 10.82±1.09 (range: 7–13) years. Results. In SR group, the mean HSS score improved significantly from 38.63±8.76 to 87.67±6.62, the mean VAS score decreased significantly from 7.37±0.24 to 0.45±0.12. the mean range of motion improved significantly from 105.52°±7.78°to 124.32°±8.12° (p<0.001). In MR group, the mean HSS score improved significantly from 38.75±8.34 to 89.29±5.21, the mean VAS score decreased significantly from 7.62±0.26 to 0.33±0.10. the mean range of motion improved significantly from 104.18°±7.62° to 122.52°±8.03°(p<0.001). (See Figure 1) Clinical and functional improvements had no significant differences between the two groups. 6 complications were noted in SR group, including 2 cases of prosthetic loosening, 1 case of periprosthetic osteolysis, 3 cases of periprosthetic bright lines.6 complications were noted in MR group, including 2 cases of prosthetic loosening and 4 cases of periprosthetic bright lines. No case of infection was observed in two groups. Survivorship using Kaplan-Meier survival analysis was 97.5% (95% confidence interval [CI]: 96.8–98.3%) for the SR at 10 years and 98.3% (95% CI: 97.3–99.5%) for the MR group at 10 years, with no significant difference (p=0.755). (See Figure 2). Conclusion. This study suggested that both single-radius and multi-radius posterior stabilized prostheses can lead to satisfactory outcomes for clinical function, radiological evaluation and survivorship among RA patients undergoing TKA, and no significantly clinical differences was shown in two types of prostheses

Abstract. Objectives. Patella resurfacing in primary total knee arthroplasty (TKA) remains a contentious issue. Australian rates of patellar resurfacing are 66.6%, significantly higher compared to UK rates of 8–15% and Swedish rates of 2%. Resurfacing has gained popularity in Australia since registry data has shown decreased revision rates with no increase in patellar component related complications. We present for discussion an analysis of 113,694 total knee arthroplasties using commonly implanted prostheses in the UK. Methods. We included all TKA's since the Australian register's conception on 01/09/1999 for a primary diagnosis of osteoarthritis involving the use of either the Triathlon or Duracon implant with and without patellar components. The primary outcome of the study was time to revision for Triathlon's resurfaced and non-resurfaced prosthesis compared to the Duracon's equivalent data. We also analysed the reasons for revision between the 4 groups, type of revision and complication rates. We then compared minimally stabilised and posterior stabilised prostheses. Results. The cumulative revision rate for Triathlon prostheses with resurfacing after 12 years was 3.2% (95% CI, 2.9% to 3.6%) compared to 5.6% (95% CI, 5.0% to 6.2%) without resurfacing. Duracon's equivalent data was 6.3% with resurfacing and 5.9% without resurfacing. Triathlon prosthesis with resurfacing have much lower rates of revision due to loosening, patellofemoral pain, patellar erosion compared to unresurfaced Triathlon prostheses. Conclusion. Triathlon with re-surfacing has lower revision rates regardless of age or BMI. Previous concerns regarding patellofemoral loosening, tibial wear, maltracking relate to Duracon only, indicating the importance of implant specific studies. Declaration of Interest. (b) declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research reported:I declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project

Introduction. Robotics have been applied to total knee arthroplasty (TKA) to improve surgical precision in component placement and joint function restoration. The purpose of this study was to evaluate prosthetic component alignment in robotic arm-assisted (RA)-TKA performed with functional alignment and intraoperative fine-tuning, aiming for symmetric medial and lateral gaps in flexion/extension. It was hypothesized that functionally aligned RA-TKA the femoral and tibial cuts would be performed in line with the preoperative joint line orientation. Methods. Between September 2018 and January 2020, 81 RA cruciate retaining (CR) and posterior stabilized (PS) TKAs were performed at a single center. Preoperative radiographs were obtained, and measures were performed according to Paley's. Preoperatively, cuts were planned based on radiographic epiphyseal anatomies and respecting ±3° boundaries from neutral coronal alignment. Intraoperatively, the tibial and femoral cuts were modified based on the individual soft tissue-guided fine-tuning, aiming for symmetric medial and lateral gaps in flexion/extension. Robotic data were recorded. Results. A total of 56 RA-TKAs performed on varus knees were taken into account. On average, the tibial component was placed at 1.9° varus (SD 0.7) and 3.3° (SD 1.0) in the coronal and sagittal planes, respectively. The average femoral component alignment, based on the soft tissue tensioning with spoons, resulted as follows: 0.7° varus (SD 1.7) in the coronal plane and 1.8° (SD 2.1) of external rotation relative to surgical transepicondylar axis in the transverse plane. A statistically significant linear direct relationship was demonstrated between radiographic epiphyseal femoral and tibial coronal alignment and femoral (r=0.3, p<0.05) and tibial (r=0.3, p<0.01) coronal cuts, resepctively. Conclusion. Functionally aligned RA-TKA performed in varus knees, aiming for ligaments’ preservation and balanced flexion/extension gaps, provided joint line respecting femoral and tibial cuts on the coronal plane

The goals of total knee arthroplasty (TKA) are to relieve pain, restore function, and provide a stable joint. In regard to types of implants, the workhorses are posterior cruciate retaining (CR), posterior stabilised (PS), and posterior stabilised constrained (PSC) designs. However, the continuum of constraint now ranges from standard cruciate retaining (CR-S) to CR lipped (CR-L), to anterior stabilised (CR-AS), to posterior stabilised, to a PS “plus” that fits with a PS femoral component but provides a small degree of varus-valgus constraint, to a PSC or constrained condylar type of device, to a rotating hinge. As the degree of deformity, bone loss, contracture, ligamentous instability and osteopenia increases, so does the demand for prosthetic constraint. When deformity is minimal and the posterior cruciate ligament (PCL) is intact and functional, a CR-S device is appropriate. For moderate deformity with deficiency or compromise of the PCL, a CR-AS or posterior stabilised device is warranted. In severe cases, with attenuation or absence of either of the collateral ligaments, a constrained condylar device, with options of stems, wedges and augments, is advisable. In salvage situations, when both collaterals are compromised, a rotating hinge should be utilised. Prerequisites for use of a CR-S device are an intact PCL, balanced medial and lateral collateral ligaments, and equal flexion and extension gaps. With a CR-L bearing, a slight posterior lip is incorporated into the sagittal profile of the component to provide a small amount of extra stability in the articulation. It is important for the surgeon to be aware of the design features of the implant system he or she is using. For example, in a system where the CR-S bearing has 3 degrees of posterior slope and the CR-L bearing has no slope, the thickness of a CR-L bearing posteriorly is approximately 2mm greater than the CR-S. A CR-L bearing is indicated for to provide stability where the flexion gap is just slightly looser than the extension gap and the PCL is intact. If the patient's knee is somewhat lax in flexion and stable in extension, a CR-L bearing may help to stabilise both the flexion and extension gaps yet still allow the knee to obtain full extension, whereas if a CR-S bearing in the next thicker size is used to stabilise the flexion gap, a flexion contracture may result. CR-AS bearings are indicated when the flexion and extension gaps are balanced, but the PCL is deficient, and the surgeon does not want to change to a PS design, which requires additional bony resection of intercondylar notch. The PCL is one of the strongest ligaments in the knee, and affords inherent stability to the TKA. In flexion, the PCL not only affords AP stability, but also imparts flexion gap stability, acting as a lateral stabiliser of the medial compartment and a medial stabiliser of the lateral compartment. The PCL has a crucial role with respect to femoral rollback, which imparts added efficiency to the extensor mechanism. PCL retention is a more biologically preserving operative intervention than PS-TKA

Introduction. Femoral periprosthetic fractures above TKA are commonly treated with retrograde intramedullary nailing (IMN). This study determined if TKA design and liner type affect the minimum knee flexion required for retrograde nailing through a TKA. Methods. Twelve cadaveric specimens were prepared for six single radius (SR) TKAs and six asymmetric medial pivot (MP) TKAs. Trials with 9mm polyethylene liners were tested with cruciate retaining (CR), cruciate substituting (CS) and posterior stabilizing (PS) types. The knee was extended to identify the minimum knee flexion required to allow safe passage of the opening reamer while maintaining an optimal fluoroscopic starting point for retrograde nailing. Furthermore, the angle of axis deviation between the reamer and the femoral shaft was calculated from fluoroscopic images. Results. In all specimens, the reamer entry point was posterior to Blumensaat's line. In the SR TKA, the average flexion required was 70, 71 and 82 degrees for CR, CS and PS respectively. The required flexion in PS was significantly greater than the other designs (p=0.03). In the MP TKA, the average flexion required was 74, 84 and 123 degrees for CR, CS and PS respectively. The required flexion was significantly greater in CS and PS designs (p<0.0001). Femoral component size did not affect the minimum flexion required. Furthermore, the entry reamer required 9.2 (SR) and 12.5 (MP) degrees of posterior axis deviation from the femur. Conclusions. Our study illustrates four novel factors to consider when performing retrograde nailing through TKA. First, significant knee flexion is required to obtain an ideal radiographic starting point when retaining the liner. Second, PS implants require more flexion with both TKA designs. Third, femoral component size does not affect the flexion required. Fourth, there is a consistent posterior axis deviation of the entry reamer from the femoral shaft, explaining the commonly created extension deformity

Background:. We studied the effect of posterior condylar offset on maximum knee flexion after a posterior stabilised total knee arthroplasty. We also looked at gender difference and the post-operative change in posterior condylar offset. Methods:. Eighty consecutive computer navigated posterior stabilised total knee replacements were prospectively assessed intra-operatively for maximum knee flexion. The flexion angle was measured and recorded with an imageless computer navigation system (Brainlab) before and after implantation of the prosthesis. This was correlated with a radiological review of the posterior condylar offset pre- and post-operatively, as defined by posterior condylar offset ratio (PCOR) originally described by Soda (2007) and modified by the Bristol Knee Group (2010). Results:. No relationship could be found between change in posterior femoral offset ratio and the change in knee flexion before and after implantation of the prosthesis (p = 0.46.)This was especially true for female subjects (p = 0.87.)For male patients there was a trend towards an inverse relationship demonstrating decreasing flexion with an increase in PCOR (p = 0.16.) PCOR increased in 91 % of cases and overall increased from an average of 0.44 pre-operatively to 0.49 post-operatively. The increase in PCOR was smaller where a large pre-operative PCOR was present (p = 0.0006.)Pre-operative flexion correlated significantly with postoperative flexion (p = 0.00.)There was no difference in PCOR between male and female patients. Conclusion:. Knee flexion is not influenced by a change in posterior condylar offset in posterior stabilised knees. The increase in posterior condylar offset with a posterior stabilised TKA could by explained a larger increase in the flexion gap than in the extension gap, when sectioning the posterior cruciate ligament. The PCOR increases in cases with smaller pre-operative posterior condylar offset. Pre-operative flexion is a significant predictor of postoperative flexion

The goals of total knee arthroplasty (TKA) are to relieve pain, restore function, and provide a stable joint. In regard to types of implants, the workhorses are posterior cruciate retaining (CR), posterior stabilised (PS), and posterior stabilised constrained (PSC) designs. However, the continuum of constraint now ranges from standard cruciate retaining (CR-S) to CR lipped (CR-L), to anterior stabilised (CR-AS), to posterior stabilised, to a PS “plus” that fits with a PS femoral component but provides a small degree of varus-valgus constraint, to a PSC or constrained condylar type of device, to a rotating hinge. As the degree of deformity, bone loss, contracture, ligamentous instability and osteopenia increases, so does the demand for prosthetic constraint. When deformity is minimal and the posterior cruciate ligament (PCL) is intact and functional, a CR-S device is appropriate. For moderate deformity with deficiency or compromise of the PCL, a CR-AS or posterior stabilised device is warranted. In severe cases, with attenuation or absence of either of the collateral ligaments, a constrained condylar device, with options of stems, wedges and augments, is advisable. In salvage situations, when both collaterals are compromised, a rotating hinge should be utilised. Prerequisites for use of a CR-S device are an intact PCL, balanced medial and lateral collateral ligaments, and equal flexion and extension gaps. With a CR-L bearing, a slight posterior lip is incorporated into the sagittal profile of the component to provide a small amount of extra stability in the articulation. It is important for the surgeon to be aware of the design features of the implant system he or she is using. For example, in a system where the CR-S bearing has 3 degrees of posterior slope and the CR-L bearing has no slope, the thickness of a CR-L bearing posteriorly is approximately 2mm greater than the CR-S. A CR-L bearing is indicated for to provide stability where the flexion gap is just slightly looser than the extension gap and the PCL is intact. If the patient's knee is somewhat lax in flexion and stable in extension, a CR-L bearing may help to stabilise both the flexion and extension gaps yet still allow the knee to obtain full extension, whereas if a CR-S bearing in the next thicker size is used to stabilise the flexion gap, a flexion contracture may result. CR-AS bearings are required less frequently. They are indicated when the flexion and extension gaps are balanced, but the PCL is deficient, and the surgeon does not want to change to a PS design, which requires additional bony resection of intercondylar notch. The PCL is one of the strongest ligaments in the knee, and affords inherent stability to the TKA. In flexion, the PCL not only affords AP stability, but also imparts flexion gap stability, acting as a lateral stabiliser of the medial compartment and a medial stabiliser of the lateral compartment. The PCL has a crucial role with respect to femoral rollback, which imparts added efficiency to the extensor mechanism. PCL retention is a more biologically preserving operative intervention than PS-TKA

Purpose. Two-stage re-implantation after infection of Total Knee Arthroplasty (TKA), remains the gold standard to which other forms of treatment should be compared. The primary purpose of this study was to determine the rates of failure and functional outcome of two stage revision TKA for treatment of infection comparing cemented posterior stabilized compared to constrained condylar implants. Method. The study group included 25 consecutive patients who had two stage revision TKA to treat infection with an average follow up of 3.25 1.5 years (range 2–6). In all patients the diagnosis of infection was made using standard serum parameters as well as aspiration for joint fluid analysis. Eight patients had posterior stabilized TKAs and 17 patients with had constrained condylar TKAs. Clinical evaluation included the Knee Society Knee Scores (KSKS) at each follow-up visit as well as a detailed record of any difficulties or complications. Results. No patient (8/8) in the LPS posterior stabilized group and 16 of 17 (94.1%) patients in the LCCK constrained condylar group, had any complaint indicative of instability. Two patients (8%) had re-infection (1 in each group). There was no significant difference between the knee scores (p=0.64) and function scores (p=0.38) of the LPS posterior stabilized and LCCK constrained condylar groups at latest follow up. Conclusion. Our findings suggest that the strategy of using the least constrained implants that provide adequate stability as judged intra-operatively is appropriate also in 2 stage revision TKAs for infection

Background:. The safety implications of achieving high flexion after TKA and the use of high flexion prostheses remain issues of concern. It is possible that different designs have different clinical and radiological results and complications, such as, early aseptic loosening. However, little information is available on the clinical results of TKAs performed using single-radius, high-flex posterior stabilized design. Accordingly, this study was undertaken to document results of single-radius, high-flex posterior stabilized TKAs with minimum 7-year follow-up. Methods:. From April 2003 to February 2006, 308 patients (455 knees) underwent TKA using single-radius, high-flex posterior stabilized design and among those patients, 251 patients (388 knees) included in this study who were able to be followed up for a minimum 7 year. Clinical results were evaluated using Knee Society Knee scores (KSKS) and Knee Society Function scores (KSFS) at last follow-up. The passive knee flexion was measured using a goniometer before and after surgery. The survival rate of the implants and implant-specific complications such as osteolysis or loosening were investigated. The osteolysis or loosening around the components was recorded according to the Knee Society Radiological scoring System. Results:. Mean Knee Society Knee score improved from 48.2 preoperatively to 96.8 postoperatively and mean Function score improved from 49.7 preoperatively to 74.2 postoperatively, respectively. The average range of motion (ROM) improved from 112.7° preoperatively to 131.5° postoperatively. Postoperative mechanical axis deviation (MAD) was within −3° to 3°, in 316 knees (81.4%). Non-progressive osteolysis was observed at zone 4 of the femoral component in eight knees (2.06%), at zone 3 of the tibial component in one knee (0.26%), at zone 2 of the tibial component in two knees (0.52%), and at zone 1 of the tibial component in thirteen knees (3.35%) in anteroposterior view. Two cases were revised due to infection and recurrent hemarthrosis. However, no complications, like early aseptic loosening, that have been associated with high flexion designs were observed. Conclusions:. Clinical results for TKAs conducted using a single-radius, high-flex posterior stabilized design with a minimum 7-year follow-up were favorable. Furthermore, no high flexion implant-specific complications such as early aseptic loosening were encountered

Aims: In this study, data from previously published survival analysis life tables of primary total condylar type TKRs has been combined to enable comparison of different design features. In particular, does posterior stabilisation or metal backing of the tibial component improve the longevity of primary cemented þxed bearing condylar type TKRs?Methods: To be included, the article had to give 5 or more years results of a primary cemented þxed bearing condylar type TKRs including a survival analysis life table. Series performed on a selected patient group (for example young age, elderly or rheumatoid arthritis) were excluded to reduce possible bias. When 2 series of the same implant from the same institution were available, the most recent article with the longest follow up was used. Results: Survival analysis data from 16 papers (5950 knees) was combined to compare design features. There was no difference in survival between posterior stabilised implants and those that were not or between metal-backed and all-polyethylene tibial components. Those all-polyethylene tibial components that were not stabilised had signiþcantly better survival than metal-backed, non stabilised tibial components and posterior stabilised, metalbacked components (p< 0.05) but not posterior stabilised, all-polyethylene components. Conclusions: Using the currently available literature, posterior stabilisation or metal backing of the tibial component does not improve the longevity of primary cemented þxed bearing condylar type TKRs

The goals of total knee arthroplasty (TKA) are to relieve pain, restore function, and provide a stable joint. In regard to types of implants, the workhorses are posterior cruciate retaining (CR), posterior stabilised (PS), and posterior stabilised constrained (PSC) designs. However, the continuum of constraint now ranges from standard cruciate retaining (CR-S) to CR lipped (CR-L), to anterior stabilised (CR-AS), to posterior stabilised, to a PS “plus” that fits with a PS femoral component but provides a small degree of varus-valgus constraint, to a PSC or constrained condylar type of device, to a rotating hinge. As the degree of deformity, bone loss, contracture, ligamentous instability and osteopenia increases, so does the demand for prosthetic constraint. When deformity is minimal and the posterior cruciate ligament (PCL) is intact and functional, a CR-S device is appropriate. For moderate deformity with deficiency or compromise of the PCL, a CR-AS or posterior stabilised device is warranted. In severe cases, with attenuation or absence of either of the collateral ligaments, a constrained condylar device, with options of stems, wedges and augments, is advisable. In salvage situations, when both collaterals are compromised, a rotating hinge should be utilised. Prerequisites for use of a CR-S device are an intact PCL, balanced medial and lateral collateral ligaments, and equal flexion and extension gaps. With a CR-L bearing, a slight posterior lip is incorporated into the sagittal profile of the component to provide a small amount of extra stability in the articulation. It is important for the surgeon to be aware of the design features of the implant system he or she is using. For example, in a system where the CR-S bearing has 3° of posterior slope and the CR-L bearing has no slope, the thickness of a CR-L bearing posteriorly is approximately 2 mm greater than the CR-S. A CR-L bearing is indicated for to provide stability where the flexion gap is just slightly looser than the extension gap and the PCL is intact. If the patient's knee is somewhat lax in flexion and stable in extension, a CR-L bearing may help to stabilize both the flexion and extension gaps yet still allow the knee to obtain full extension, whereas if a CR-S bearing in the next thicker size is used to stabilise the flexion gap, a flexion contracture may result. CR-AS bearings are required less frequently. They are indicated when the flexion and extension gaps are balanced, but the PCL is deficient, and the surgeon does not want to change to a PS design, which requires additional bony resection of intercondylar notch. The PCL is one of the strongest ligaments in the knee, and affords inherent stability to the TKA. In flexion, the PCL not only affords AP stability, but also imparts flexion gap stability, acting as a lateral stabilizer of the medial compartment and a medial stabiliser of the lateral compartment. The PCL has a crucial role with respect to femoral rollback, which imparts added efficiency to the extensor mechanism. PCL retention is a more biologically preserving operative intervention than PS-TKA

Objectives: The purpose of this study was to assess the effect of different types of posterior stabilisation on the fusion rate of anterior lumbar interbody fusion (ALIF). Thin section CT scanning has shown a higher rate of pseudarthrosis with ALIF than previously reported with standard radiological modalities. Cadaveric studies have demonstrated that posterior stabilisation would increase stiffness of the motion segment and is likely to enhance the rate of fusion with ALIF. The results of thin section CT scanning of ALIF, with and without posterior stabilisation, has not been reported previously. Methods: Patients with discogenic back pain confirmed by discography underwent ALIF surgery as a stand alone procedure or with posterior stabilisation – using trans-laminar screws, unilateral pedicle screws or bilateral pedicle screws. Patients were followed up prospectively and thin section CT scanning was used to assess inter-body fusion. Results: The fusion rate for stand alone ALIF was 51%, for patients with supplementary stabilisation with trans-laminar screws 58%, with unilateral pedicle screws 89% and with bilateral pedicle screws 88%. When ALIF was combined with pedicle screw stabilisation a significant difference in the fusion rate was found (p< 0.01). Conclusion: The addition of pedicle screw fixation at the time of ALIF produces a significant increase in the rate of interbody fusion

Introduction. Our objective is to describe early and midterm results with the use of a new knee prosthesis as an articulating spacer in planned two-stage management for infected total knee arthroplasty. As a second objective, we compared outcomes between the group with a retained first stage and those with a completed 2-stage revision. Methods. Forty-seven patients (48 knees) from January 2012 and November 2017 underwent a 2-stage exchange with an articulating spacer with new implants was used for a chronic knee periprosthetic joint infection with a mean follow-up of 3.7 years (2–6.5 years). The most frequently identified infecting organism was MSSA (31%), MRSA (21%) or MRSE (20%). At the first stage, a new PS femoral component and a new all-polyethylene posterior stabilized (PS) tibial component or a standard PS tibial liner were cemented with antibiotic-cement, typically 3.6 gm tobramycin and vancomycin 1.5 gm. IV antibiotics for six weeks were administered. The planned reimplantation was at 3 months, but ninetteen spacers (14 all poly tibias and 5 tibial liner) were retained for over 12 months. Postoperative assessment included knee range of motion (ROM), quality of life (QOL) scores (SF-12, WOMAC, KOOS, Oxford, and UCLA scores), and a satisfaction scale from 0–100%. Results. Of the 48 knees, 8 failed due to lack of infection control, and 2 died within the first year for medical reasons (4%), giving a failure rate of 17% (8/46). One of these knees was not revised due to poor medical status. Of the remaining 7, 2 had a repeat 2-stage exchange, one a single stage revision and 4 irrigation and debridement with retained implants. All 7 had a successful outcome with infection control after this, leaving a permanent failure rate of 2% (1/46). Five of the 19 knees with initially retained implants were revised to a second stage after 12 months for continued pain or instability (1/14 all poly tibia and 4/5 PS liner). There were no significant differences in final range of motion or QOL scores between patients with a retained first stage procedure and those who underwent a second stage operation. Also, there was no statistically significant difference in the initial failure rate due to infection between patients with a complete 2-stage revision and those with a retained first stage (19% (6/31) vs. 14% (2/14), respectively; p=0.613). Conclusions. When an all poly tibial implant is used a spacer in two-stage exchange arthroplasty, it may be retained for over 12 months, with no difference in infection control, range of motion, and quality of life assessment to patients with complete 2-stage revision surgery. With this technique, the second stage may be delayed in patients who are doing well, and may never need to be revised, hence we propose the new term “one-and-a-half stage exchange”

Bicruciate ligament retaining total knee arthroplasty preserves all of the ligaments of the knee while still addressing the ligament balance and the flexion-extension gaps. The concept of cruciate ligament preservation is not new and both Townley and Cartier designed prostheses in the late 1980s that did preserve all of the ligaments. Their results were quite acceptable for that time in knee replacement surgery but the posterior stabilised and cruciate retaining designs controlled most of the market. The surgical technique for cruciate ligament preservation was more difficult, and without clear clinical benefit, most surgeons gravitated towards the cruciate retaining and posterior stabilised designs. In the late 1990s, evaluation of the total knee arthroplasty began to assess knee kinematics in addition to pain and functional outcomes. At the same time, studies on the unicondylar knee arthroplasty demonstrated impressive scores in motion and patient satisfaction with preservation of all of the ligamentous structures of the knee. Over the past two years, new designs that preserve all of the ligaments of the knee have returned to the market. The instruments have been improved and the prostheses have been changed to respect the kinematics of the knee. Fifteen to twenty percent of all total knee replacement patients are not completely satisfied with the surgery and the authors believe that complete ligament preservation may address this complaint

Purpose. The purpose of this study was to compare intercompartmental loads and the proportion of knees with unbalanced loads after tensiometer-assisted balancing (TAB) between cruciate retaining (CR) and posterior stabilized (PS) total knee arthroplasty (TKA). Materials and Methods. Forty-five CR and 45 PS TKAs using a single prosthesis were prospectively evaluated. The intercompartmental loads in 10°, 45°, and 90° of knee flexion after TAB were evaluated; the proportions of load imbalance (medial load – lateral load >15 lbs) in each flexion angle after TAB were investigated. The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of TAB were calculated, with the sensor-balanced loads considered the reference standard. Results. The average loads of the medial compartment in CR TKA were greater than the adequate load (55 lbs) in every knee flexion angle; those of PS TKA were <55 lbs. The proportions of the load imbalance were >50% in every knee flexion angle in both CR and PS TKA (CR >64.4% and PS >57.8%), and there was no difference between the groups (p > 0.515). The sensitivity, specificity, PPV, and NPV of TAB were 91.7%, 66.7%, 57.9% and 94.1%, respectively, in CR, and 100%, 62.5%, 40 %, and 100%, respectively, in PS TKA. Conclusions. The appropriate load balancing from the tensiometer seemed to be difficult in both CR and PS TKA. The intraoperative load sensor had a role in accurate load balancing to overcome the poor PPV of the tensiometer in both types of TKA

The most recent Australian registry has a database of 547,407 knee arthroplasties, having added over 52,000 in 2016. Total knee arthroplasties (TKA) comprise 83.8%, revisions (RevTKA) 8.1% and “partials of all types” 8.1%. Since 2003, the percent of TKA has increased from 76.7%, RevTKA has stayed stable and partial replacements have declined from 14.5%. In the last year, however, TKA declined slightly. There is a slightly higher percentage of women (56.1%) undergoing TKA and this has remained very stable since 2003. Revision rates are slightly higher for men. Percentages of the youngest (<55) and oldest (>85) are small and stable. The 75–84 year olds have declined as 55–74 year olds have increased. This represents a gradual shift to earlier TKA surgery. More patella are resurfaced and this is a gradual trend with a cross over in 2010 when half were resurfaced. Computer navigation is progressively more popular and now accounts for almost 30% of cases. Cement fixation is also increasing and accounts for about 65% of cases. Crosslinked polyethylene is gradually replacing non crosslinked and in 2014 was used in 50% of cases. Revisions are performed most commonly for loosening and infection. Revision rates correlate directly with age. Loosening is the most common indication for revision in both genders, but males have a distinctly higher revision rate due to infection. Revision rates are slightly higher in all forms of mobile bearing than fixed bearing. Minimally constrained (cruciate retaining) devices are used in the majority of TKAs. Posterior stabilised implants are in slight decline, having peaked in about 2008–2010. Minimally constrained implants are in slight decline as medial pivot/medial congruent devices have been used more frequently. Revision rates are similar amongst all three implant types: PS implants are revised at a slightly higher rate. When an early Medial Pivot (MP) implant is excluded the newer version has better results. The reasons for revision are similar amongst all 3 groups with slightly higher loosening rates for PS designs. (Could this represent backside wear with older locking mechanisms, surface finish and non crosslinked poly?) The MP designs had slightly higher revision rates for “pain”, which is not recognised as a reasonable indication for revision. Revision rates are steadily higher for TKAs without patella resurfacing over 16 years, but the questions as to whether: i. the surgeries were secondary resurfacings or full revisions or ii. if secondary resurfacings eliminated pain are unknown. The combinations at greatest risk of revision were a posterior stabilised or medial pivot arthroplasty without patellar resurfacing. Cementless fixation leads to a higher revision rate. If age and computer navigation are evaluated in terms of revision rates, young patients with and without computer navigated arthroplasties failed at the highest rates, distinct from patients >65. However, if failure rates due only to loosening are evaluated, then computer navigation leads to a lower revision rate in the <65 group. This has been interpreted as the protective effect of better component position that only shows up in patients who use the arthroplasty more aggressively. Patient specific instrumentation (PSI) or Individual Designed Instrumentation (IDI) were revised at marginally higher rates than conventional instrumentation. Crosslinked polyethylene appears to be superior at 12 years (CRR= 4%) versus non crosslinked polyethylene (CRR>7%). This is the result of fewer failures due to loosening with crosslinked poly. The superiority of crosslinked poly was greater in the younger, more active patient

Introduction: Anterior lumbar interbody fusion (ALIF) with posterior stabilisation is an established treatment for degenerative disc disease. 1. Some previous reports have advocated a goal of 360 degree fusion, and condemned posterior stabilisation as it does not achieve fusion of the posterior facet joints. 2. Others have claimed that the concept of a ‘locked pseudarthrosis’ gives satisfactory clinical results. 3. There is also a contention that private or self-funding patients achieve better results after spinal fusion compared to those treated under compensation or Dept. Veterans Affairs (DVA) schemes. Methods: Twenty patients who had undergone an ALIF with posterior stabilisation were retrospectively reviewed. All had a follow-up greater than 12 months. 13 patients were private and 7 non-private. The groups were aged and sex matched. Radiological assessment of fusion was made with reconstruction CT scans. Oswestry Disability Index (ODI) scores were recorded preoperatively, 6 months and 12 months post operation. Results: Patients with locked pseudarthrosis showed no significant difference in outcome compared to those with radiological fusion. Both groups showed signifi cant improvement in ODI scores after ALIF (mean preop. = 52 – range 16-74; mean postop. = 18 – range 0-52; p< 0.01). There was a significantly greater improvement (p< 0.02) in ODI scores in private patients (mean reduction = 41 points) compared to worker’s compensation or DVA patients (mean reduction = 22 points). Discussion: The results indicate that ALIF with posterior stabilisation can achieve good clinical results even with a ‘locked pseudarthrosis’. While there is no significant difference between outcomes in different health funding groups shown in the study, carefully patient select for this treatment is the key to success

We hypothesised that an independent Notch Trial is essential on the same lines as other Component Trials-Femoral, Tibial and Patellar - in posterior stabilised total knee arthroplasty. Therefore we evolved Notch Trial to visually ascertain the adequacy of intercondylar resection and eliminate the possibility of femoral intercondylar fractures. We undertook a retrospective study to evaluate Notch Trial by the frequency of the need to remove osteophytes or file uneven surfaces in intercondylar resection by using the detachable box part of the trial femoral component, assess occurrence of distal femoral intercondylar fractures and demonstrate Notch Trial in posterior stabilised total knee replacement. We studied 206 patients, 113 females and 93 males, who underwent consecutive primary posterior stabilised total knee replacements applying Notch Trial between 2000 and 2008 in a District General Hospital under our team. Outcome Measurements were 1) frequency of the need to remove osteophytes or file uneven surfaces in intercondylar resection and 2) occurrence of distal femoral intercondylar fractures intraoperatively or on postoperative radiographs. We had to remove the osteophytes and file the cut surfaces in 183 (88.88%) of patients after Notch Trial. We had no distal femoral intercondylar fractures intraoperatively or on postoperative radiographs. Notch Trial allows the surgeon to directly visualise and ascertain the adequacy and precise fit of femoral notch cut with cam part of femoral component to ensure a press fit femoral component in condylar posterior cruciate substituting total knee replacement. Notch Trial prior to Femoral Component Trial effectively pre-empts intraoperative distal femoral intercondylar fractures. We recommend that Notch Trial should become part of the protocol for cruciate substituting total knee replacement and implants of all companies should have the option of a detachable box component for Notch Trial

The study was conducted to review the outcome in cases of anterior expandable interbody cages inserted through a posterior only approach. Cases selected were the anterior cage insertion and posterior stabilization patients managed by posterior only approach. Study includes the patients of various pathologies requiring 3 column support. Twenty patients were included in study. Pathology in 9 patients was tuberculosis, trauma in 3, tumours in 3, metastasis in 3 and deformities in 2patients. Patients with or without neurological deficit were included. Cases were carefully assessed and patients with single level involvement were included as more then single level involvement required more extensive exposure and possible nerve root sacrifice. Detailed neurological status was recorded. The surgery was performed in prone position and after posterior stabilization by pedicle screws the extracavitatory approach was used to insert the expandable cage. In cases of suspicious pathologies the samples for histopathology and staining were collected. Morbidity, mortality blood loss, surgical time, complications, outcome of surgery were compared with historical controls of front and back surgery. The insertion of cages from posterior approach was feasible in all carefully planned cases. None of the patients had problem related to implant in form of cage displacement. All the patients had satisfactory outcome. Posterior stabilization of spine with expandable cage insertion from posterior approach saves the operating time, spares the additional surgical incision and blood loss without compromising the outcome. In carefully planned surgeries it gives excellent results irrespective of etiology

Objective: This study investigates whether the sequence of anterior and posterior procedure has any effect on the lordosis, disc height and stability in combined A-P fusion of the lumbar spine. Design: A biomechanical study on cadaver lumbar spine. Materials and Methods: Twelve motion segments (between L2–L5) from four cadaver lumbar spines were studied. Anterior and posterior stabilization were performed using a Syncage (Synthes, Switzerland) of appropriate sizes, and translaminar screws respectively. Load-deformation characteristics in flexion-extension, lateral bending, and torsion were tested in a material-testing machine (Dartec, Stourbridge, UK) with 7.5Nm cyclical load. Angular deformation of each motion segment was determined simultaneously, by 2-D optical reflex camera system (Pro-reflex, Qualysis, Sweden). Disc height, and angle of lordosis between the adjacent endplates were determined from lateral radiographs. These parameters were measured in the intact spine, after A-P fixation with front first, and after back procedure first. Results: Compared to the intact spine, the disc height was significantly increased (p< 0.05) when Syncages were introduced before posterior fixation, but not when posterior fixation was done first (p = 0.12). The angle of lordosis was increased significantly with posterior stabilization first, but only marginally, with anterior stabilization first. The stability of the motion segments increased significantly with combined A-P fusion, compared to either anterior or posterior fixation alone. With posterior stabilization first, the stability in all directions were greater but not statistically significant, compared to anterior stabilization first (p> 0.05). Conclusion: In combined A-P fusion of lumbar spine, the lordosis is better restored when posterior stabilization is done first, but disc height is better restored when the anterior stabilization is performed first. Stability of fixation is not significantly affected by altering the sequence

Summary. The 80% porous structure of trabecular metal allows for bone ingrowth in more than 90% of the available surface. The Nexgen LPS Uncemented Knee using a trabecular metal tibial component has performed well at minimum of 5 years’ follow-up. Introduction. Total Knee Arthroplasty prostheses most frequently used in today's practice have cemented components. These have shown excellent clinical results. The fixation can however weaken with time, and cement debris within the articulation can lead to accelerated wear. Cementless implants are less commonly used, but some have also shown good long-term clinical results. The potential advantages of cementless implants are retention of bone stock, less chance of third-body wear due to the absence of cement, shorter operative time, and easier treatment of periprosthetic fractures. The posterior stabilised knee replacement has been said to increase tangential shear stresses on the tibial component and increases contact stresses on the cam and post mechanism hence the great debate of cruciate retaining or cruciate sacrificing implants. Objectives. We report the results of a prospective cohort of consecutive primary total knee arthroplasties using an uncemented posterior stabilised prosthesis using a trabecular metal (tantalum) tibial component at a minimum 5-year follow-up. Methods. Prospective 5 year follow-up of patients undergone an uncemented posterior stabilised total knee replacement using a trabecular metal tibial component (NexgenLPS). Clinical examination, Oxford knee score, Knee society score, SF12 and radiological evaluation undertaken at review. Results. 81 patients, 45 female, 36 male. Left 31, Right 50. Mean age 74.3 yrs range (51–90). SF12, mean: 31.8 range (25–37). Oxford Knee Score Pre-op Mean 20.1 range (9–36) Post op: Mean 32.1 range (9–48). Knee Society score. Pain Mean 91.8; range (60–100). Functional score mean 76.2; range (30–100). Mean Range of movement 110.5 degrees range (90–125). No evidence of loosening at 5 yrs. No deep infection. No Revisions. Conclusion. Although there are a variety of methods of achieving satisfactory initial fixation in cementless components, trabecular metal has an advantage owing to its cellular structure resembling bone. The 80% porous structure of trabecular metal allows for bone ingrowth in more than 90% of the available surface. The Nexgen LPS Uncemented Knee using a trabecular metal tibial component used in this series has shown no evidence of loosening at a minimum of 5 years’ follow-up and the prosthesis as a whole has performed very well clinically. Its early results are comparable to those prostheses most commonly used as reported by the arthroplasty registers. The longer term results from this prosthesis are awaited with interest

The purpose of this study was to examine the influence of weight-bearing on the measurement of in vivo wear of total knee replacements using model-based RSA at 1 and 2 years following surgery. Model-based RSA radiographs were collected for 106 patients who underwent primary TKR at a single institution. Supine RSA radiographs were obtained post-operatively and at 6-, 12-, and 24-months. Standing (weight-bearing) RSA radiographs were obtained at 12-months (n=45) and 24-months (n=48). All patients received the same knee design with a fixed, conventional PE insert of either a cruciate retaining or posterior stabilized design. Ethics approval for this study was obtained. In order to assess in vivo wear, a highly accurate 3-dimensional virtual model of each in vivo TKA was developed. Coordinate data from RSA radiographs (mbRSA v3.41, RSACore) were applied to digital implant models to reconstruct each patient's replaced knee joint in a virtual environment (Geomagic Studio, 3D Systems). Wear was assessed volumetrically (digital model overlap) on medial and lateral condyles separately, across each follow-up. Annual rate of wear was calculated for each patient as the slope of the linear best fit between wear and time-point. The influence of weight-bearing was assessed as the difference in annual wear rate between standing and supine exams. Age, BMI, and Oxford-12 knee improvement were measured against wear rates to determine correlations. Weight bearing wear measurement was most consistent and prevalent in the medial condyle with 35% negative wear rates for the lateral condyle. For the medial condyle, standing exams revealed higher mean wear rates at 1 and 2 years, supine, 16.3 mm3/yr (SD: 27.8) and 11.2 mm3/yr (SD: 18.5) versus standing, 51.3 mm3/yr (SD: 55.9) and 32.7 mm3/yr (SD: 31.7). The addition of weight-bearing increased the measured volume of wear for 78% of patients at 1 year (Avg: 32.4 mm3/yr) and 71% of patients at 2 years (Avg: 48.9 mm3/yr). There were no significant (95% CI) correlations between patient demographics and wear rates. Volumetric, weight-bearing wear measurement of TKR using model-based RSA determined an average of 33 mm3/yr at 2 years post-surgery for a modern, non-cross-linked polyethylene bearing. This value is comparable to wear rates obtained from retrieved TKRs. Weight-bearing exams produced better wear data with fewer negative wear rates and reduced variance. Limitations of this study include: supine patient imaging performed at post-op, no knee flexion performed, unknown patient activity level, and inability to distinguish wear from plastic creep or deformation under load. Strengths of this study include: large sample size of a single TKR system, linear regression of wear measurements and no requirement for implanted RSA beads with this method. Based on these results, in vivo volumetric wear of total knee replacement polyethylene can be reliably measured using model-based RSA and weight-bearing examinations in the short- to mid–term. Further work is needed to validate the accuracy of the measurements in vivo

PURPOSE. Total knee arthroplasty (TKA) is a successful technique for treating painful osteoarthritic knees. However, the patients' satisfaction is not still comparable with total hip arthroplasty. Basically, the conditions with operated joints were anterior cruciate ligament (ACL) deficient knees, thus, the abnormal kinematics is one of the main reason for the patients' incomplete satisfaction. Bi-cruciate stabilized (BCS) TKA was established to reproduce both ACL and posterior cruciate ligament (PCL) function and expected to improve the abnormal kinematics. However, there were few reports to evaluate intraoperative kinematics in BCS TKA using navigation system. Hence, the aim in this study is to reveal the intraoperative kinematics in BCS TKA and compare the kinematics with conventional posterior stabilized (PS) TKA. Materials and Methods. Twenty five consecutive subjects (24 women, 1 men; average age, 77 years; age range, 58–85 years) with varus osteoarthritis undergoing navigated BCS TKA (Journey II, Smith&Nephew) were enrolled in this study. An image-free navigation system (Stryker 4.0 image-free computer navigation system; Stryker) was used for the operation. Registration was performed after minimum medial soft tissue release, ACL and PCL resection, and osteophyte removal. Then, kinematics including tibiofemoral rotational angles from maximum extension to maximum flexion were recorded. The measurements were performed again after implantation. We compared the kinematics with the kinematics of paired matched fifty subjects who underwent conventional posterior stabilized (PS) TKA (25 subjects with Triathlon, Stryker; 25 subjects with PERSONA, ZimmerBiomet) using navigation statistically. Results. Preoperative tibiofemoral rotational kinematics were almost the same between the three implants groups. Kinematics at post-implantation found that tibia was significantly internally rotated compared to the kinematics at registration in all three implants at maximum extension position (p<0.05), however the tibial rotational position with BCS TKA was significantly externally rotated at maximum extension position, compared to the other two implant position (p<0.05). The tibial rotational position with Triathlon PS TKA was externally rotated at 60 degrees of flexion compared to the other two implant position, however the results were not statistically significant. Discussion and Conclusion. Previous study found that PCL resection changed tibial rotational position and the amount of tibial internal rotation, affecting postoperative maximum flexion angles. This study found that BCS TKA can reduce the amount of rotational changes, compared to conventional PS TKA. Further studies are needed to investigate the kinematic changes in BCS TKA affect the postoperative clinical outcomes

First generation condylar knee replacements suffered from 2 prominent observations: Difficulty in stair climbing and Limited range of motion. Improved understanding of knee kinematics, the importance of femoral rollback, and enhanced stability in flexion led to 2 differing schools of thought: posterior cruciate ligament retention or posterior cruciate substitution. The advantages of posterior cruciate substitution include predictable CAM-post engagement leading to rollback, predictable ROM, stability during stair climbing, ease of knee balancing regardless of degree of angular deformity, and avoidance of issues such as PCL tightness / laxity at time of index procedure, as well as late ligament disruption leading to late instability. Evolution has shown that human appendages that no longer served a purpose, slowly shrivel up. As we have seen with the appendix, the coccyx, and the erector pili muscles, these vestigial organs no longer are necessary for daily function and are destined for obsolescence. I submit: the PCL in knee arthroplasty IS THE VESTIGIAL ORGAN: not the posterior stabilizing mechanism!

Purpose: Retrograde nailing is emerging among methods proposed or stabilisation of femoral fractures above total knee arthroplasties (TKA). Material and methods. Between June 1994 and may 2000, 12 fractures above TKA were treated by retrograde nailing. These fractures occurred 43 months (4–51) after implantation of the TKA in three men and women aged 74 years (43–88). The fracture was situated just above the prosthetic trochlea in ten, and distant from the implant in two. The posterior cruciate ligament was preserved in six TKA and six were posterior stabilised prostheses. Indications for arthroplasty were degenerative joint disease in nine and rheumatoid polyarthritis in three. Four patients had proximal implants (one fixation and three prostheses). A percutaneous approach was used except for three cases in order protect the tibial component. Closed reduction was achieved, but required an open reduction for completion in two cases. the nail was advanced just to the trochlea in patients with a preserved posterior cruciate ligament and beyond the posterior stabilisation cage for the posterior stabilised implants. The knee was mobilised immediately after surgery and total weight-bearing was encouraged four to six weeks later. Results: There was one error in the proximal aiming, one metastatic infection from a leg ulcer at three months and one tibial loosening in a polyarthritic woman 66 months after arthroplasty, i.e. 51 months after the fracture. Bone healing was achieved at two to four months. Frontal deviation was less than 5°. Recurvatum was less than 5° in eight cases, between 5° and 10° in two cases and between 10° and 20° in two others. At mean follow-up of 23 months (3–60), maximal moss of mobility was 10°. There was not worsening of pain. Discussion: Retrograde nailing leads to bone healing with satisfactory frontal alignment and minimal loss of mobility. The approach uses the initial incision, facilitating complementary procedures or revision if needed. The main problem is controlling recurvatum, even though at the follow-up reported there was no clinical impact or loosening. The limitations of this method are well defined: free medullary canal, sufficient knee flexion, compatible femoral component. The tibial obstacle in posterior stabilised implants is less well known; It should be protected during the nailing if it is high. The polyethylene insert may have to be removed temporarily in certain cases. Conclusion: The two principal problems with retrograde nailing are recognising implants compatible with this technique and controlling recurvatum. Results are acceptable with a minimally invasive technique

Introduction. Numerous fluoroscopic studies have been conducted to investigate kinematic variabilities of total knee arthroplasty (TKA). In those studies, subjects having a posterior stabilized (PS) TKA experience greater weightbearing knee flexion and posterior femoral rollback of the lateral condyle. In those same studies, subjects did experience a high incidence of variable medial condyle motion and reverse axial rotation, especially occurring when the cam engaged the post. More recently, a PS TKA was designed to accommodate both gender and ethnicity. Therefore, the objective of this study was to assess in vivo kinematics for subjects having this TKA type to determine if subjects having this PS TKA experienced more optimal knee kinematics. Methods. Twenty-five subjects in this study were asked to perform a deep knee bend to maximum knee flexion and a step-up maneuver while under fluoroscopic surveillance. All subjects were patients of one experienced surgeon and received the same PS TKA. Using a 3D-2D registration technique, the CAD models, supplied by the sponsoring company, were superimposed over x-ray images at specified increments throughout the fluoroscopic footage. The kinematics were then analyzed to evaluate lateral anterior/posterior (LAP) and medial anterior/posterior (MAP) condyle translation as well as axial rotation of the femur with respect to the tibia. Results. During the DKB activity, the average flexion for the PS TKA subjects was 1108°. On average subjects experienced a lateral condyle motion in the posterior direction of 7.3mm, with the maximum amount of posterior rollback being 12.8 mm. These same subjects experienced an average medial condyle motion in the posterior direction of 4.8 mm with the maximum amount of posterior motion being 7.8 mm. Therefore, with the lateral condyle rolling more posterior than the medial condyle, these subjects experienced an average amount of 7.1° of axial rotation, with a maximum of 12.0°. Only one subject in this study experienced a reverse axial rotation from full extension to maximum knee flexion. During the step-up maneuver, subjects consistently experienced a roll forward motion of both their condyles. Discussion. Subjects in this study experienced a high incidence and magnitude of lateral condyle posterior femoral rollback, leading a normal-like axial rotation pattern, although less in magnitude compared to the normal knee. There was variability occurring with the medial condyle as some experience experienced an anterior slide while others rolled in the posterior direction. As seen in previous studies, during mid flexion both condyles experienced a more variable motion pattern. Twenty-five subjects having a posterior cruciate retaining TKA are being added to this study to determine if retention of the PCL in a similarly designed TKA leads to more normal-like kinematic patterns

Purpose: Posterior stabilisation with a third condyle was introduced by Henri Dejour with the HLSI prosthesis. While the posterior stabilisation process has been validated, this implant still raises some problems with the tibial fixation in patients with advanced joint degeneration, leading to the development of the HLSII model. The purpose of the present retrospective work was to evaluate functional outcome and persistance of the HLSII prosthesis fixation. Material and methods: Between January 1992 and December 1993, 105 total knee arthroplasties (TKA) were performed in 94 consecutive patients using posterior stabilised HLSII prostheses. Indications were joint degeneration (40% stage 4) in 78% and polyarthritis in 19%. None of the patients were lost to follow-up but 14 patients died, six were bedridden (stroke sequela) and four were contacted by phone only. In all, 70 patients (77 TKA), mean age 66 years (22–79) were retained for clinical and radiological assessment at mean follow-up of seven years (range 6–8 years). All implants were cemented and the patella was resurfaced in all cases. Eight operators participated in this series. Junior surgeons (n=5) implanted one-third of the prostheses. Results: The mean IKS knee score rose from 27±18 points (0–63) preoperatively to 81±18 (21–100) at last follow-up, function score from 35±20 (0–75) to 64±24 (0–100) (P< 0.0001). Motion changed from 114° (60–140°) to 116° (40–135°) (NS).Eighty-six percent of the patients used stairs (13% without handrail and 28% with alternate steps) versus 52% before the intervention (1% without handrail and 1% with alternate steps). (P=0.001). Knee alignment was normal ±5° in 87% of the cases versus 27% before surgery (P< 0.0001). Seventy-nine percent of the knees had a slope ±2° (desired slope 0°). The patellar retinaculum was sectioned in one quarter of the knees which led to four of the five postoperative haematomas (no revision). Five patellar fractures were noted, including two with patellar loosening (revised) and one clunk (cured after arthroscopic release). Lucent lines observed under the medial tibial plateau in 30% of the cases (all < 1 mm) were more frequent in patients with more severe joint degeneration and genu varus preoperatively (P =0.01). There was no case of aseptic femorotibial loosening. One case of late infection (30 months) was followed by replacement arthroplasty. Survival rate, taking mechanical and/or infectious failure as the endpoint, was 97± 1.3% at 90 months. Discussion: Good axial control emphasises the reliability of the instrumentation since one-third of the prostheses were implanted by junior surgeons. Improvements in tibial fixation with the HLSII appear to be effective, particularly for stage 4 degeneration. Long-term surveillance is however necessary. The femoropatellar joint can give rise to non-infectious complications and should be improved. The concept of posterior stabilisation with a third condyle authorises good flexion amplitude and favours use of stairs

PURPOSE: To record our experience in surgical treatment of thoracic spine fractures with posterior stabilization, decompression and ligamentotaxis. MATERIALS AND METHODS: From January 2000 until July 2006, 67 patients (48 males and 19 females), aged 16 to 85 years old (average 41,2 y.o) were surgically treated in our department due to thoracic spine fractures. Preoperative X-Ray and CT scan were used in all cases while in most of the cases we performed MRI to further evaluate the damage. In all cases we performed decompression and posterior stabilization using four different hardware types and whenever possible ligamentotaxis. Continuous electrophysiological monitoring was alo ued in all operations. We recorded the pre- and postoperative neurological status, the vertebral height loss, the kyphotic angle and spinal canal occupation. Moreover we recorded the average hospitalization time, the transfusion needs as well as major and minor complications. At the follow-up we measured the loss of correction at 3, 6 and 12 months postoperatively. The follow up ranged from 4 to 48 months. RESULTS: Neurological damage was recorded in 43 % of the patients. The average preoperative kyphotic angle was 38.2° while the average spinal canal occupation was 29.8 %. The immediate postoperative correction was 16.7 °. During the follow-up we observed small, insignificant loss of correction. There were no major complications. CONCLUSION: In cases of thoracic spine fractures the surgical treatment with posterior stabilization and ligamentotaxis is offering significant stability and adequate long term results

Eighteen porous coated posterior stabilized prostheses, inserted without cement or screws have been reviewed. Six were revised within two years. One was infected. The remaining five were revised for persistent symptoms considered to be due to tibial component loosening. Three of the four improved after revision with cementing of the tibial component, the other has remained symptomatic. One patient was lost to follow-up. Clinical review of the remaining eleven was good or excellent at two years. Radiographs at two years, available in eight, revealed that all had a non progressive I mm radio-lucent line at the bone- tibial prosthesis interface. The lack of bony ingrowth and apparent symptomatic early loosening in the four revised, suggests that posterior stabilised tibial prostheses may require additional initial fixation. From our experience in this short series, it is recommend that the tibial component of this prosthesis and perhaps any other posterior stabilized design, be cemented or fixed with screws

Introduction. Instability, loosening, and patellofemoral pain belong to the main causes for revision of total knee arthroplasty (TKA). Currently, the diagnostic pathway requires various diagnostic techniques such as x-rays, CT or SPECT-CT to reveal the original cause for the failed knee prosthesis, but increase radiation exposure and fail to show soft-tissue structures around TKA. There is a growing demand for a diagnostic tool that is able to simultaneously visualize soft tissue structures, bone, and TKA without radiation exposure. MRI is capable of visualising all the structures in the knee although it is still disturbed by susceptibility artefacts caused by the metal implant. Low-field MRI (0.25T) results in less metal artefacts and offers the ability to visualize the knee in weight-bearing condition. Therefore, the aim of this study is to investigate the possibilities of low field MRI to image, the patellofemoral joint and the prosthesis to evaluate the knee joint in patients with and without complaints after TKA. Method. Ten patients, eight satisfied and two unsatisfied with their primary TKA, (NexGen posterior stabilized, BiometZimmer) were included. The patients were scanned in sagittal, coronal, and transversal direction on a low field MRI scanner (G-scan Brio, 0.25T, Esaote SpA, Italy) in weight-bearing and non-weight-bearing conditions with T1, T2 and PD-weighted metal artefact reducing sequences (TE/TR 12–72/1160–7060, slice thickness 4.0mm, FOV 260×260×120m. 3. , matrix size 224×216). Scans were analysed by two observers for:. - Patellofemoral joint: Caton-Descamps index and Tibial Tuberosity-Trochlear Groove (TT-TG) distance. - Prosthesis malalignment: femoral component rotation using the posterior condylar angle (PCA) and tibial rotation using the Berger angle. Significance of differences in parameters between weight-bearing and non-weight-bearing were calculated with the Wilcoxon rank test. To assess the reliability the inter and intra observer reliability was calculated with a two-way random effects model intra class correlation coefficient (ICC). The two unsatisfied patients underwent revision arthroplasty and intra-operative findings were compared with MRI findings. Results. In the satisfied group, a significant difference was found between TT-TG distance in non-weight-bearing and weight-bearing condition (p=0.018), with a good interrater reliability ICC=0.89. Furthermore, differences between weight-bearing and non-weight-bearing were found for the CD ratio, however, not significant (p=0.093), with a good interrater reliability ICC=0.89. The Berger angle could be measured with an excellent interrater reliability (ICC=0.94). The PCA was hard to assess with a poor interrater reliability (ICC=0.48). For one unsatisfied patient a deviation was found for tibial component rotation, according to the perioperative findings as, ‘malposition of the tibial component’. For the other unsatisfied patient revision surgery was performed due to aseptic loosening in which the MRI showed a notable amount of synovitis. Conclusion. It is possible to image the patellofemoral joint and knee prosthesis with low field MRI. Patellofemoral measurements and tibial component rotation measurements can reliably be performed. For the two patients with complaints MRI findings were consistent with intra-operative findings. Further research should focus on a larger group of patients with complaints after TKA to verify the diagnostic capacity of low field MRI for peri-prosthetic knee problems. For any figures or tables, please contact authors directly

The survivorship method of analysis has been used to compare the failure rate and overall success of 1,430 cemented primary total knee arthroplasties performed at The Hospital for Special Surgery over a 15-year period. There were 224 total condylar prostheses with a polyethylene tibia, 289 of the posterior stabilised type with an all polyethylene tibia, and 917 posterior stabilised with a metal-backed tibial component. There were 12 failures in the total condylar series, giving an average annual failure rate of 0.65% and a 15-year success rate of 90.56%. The posterior stabilised prosthesis with a polyethylene tibia showed an average annual failure rate of 0.27% and a 10-year success rate of 97.34%, and this prosthesis with a metal-backed tibial component gave an annual failure rate of 0.19% and a seven-year success rate of 98.75%. The overall survival rate was not influenced by sex or age, diagnosis or the percentage of ideal body weight. No metal-backed tibial components have yet needed revision for loosening. It seems that infection will be the major cause of failure

This study presents the results of 1188 original and innovative posteriorly stabilized TKA procedures in which the femoral bone stock is preserved with a shallow compartment insofar as possible. The TKA procedure is directly derived from Insall’s original technique, except for the posterior stabilisation design, where a third median condyle starts working at 30° of knee flexion. A total of 1188 primary TKA procedures were consecutively performed in a university hospital. Average follow-up was 30 months (0–168 months). The implants were cemented (except for 35 femoral components) and the patella resurfaced (except for nine cases). Clinical results were assessed using the IKS Score. The quality of the implantation was analysed on long-leg X-rays (1175 preoperative and 883 postoperative long-leg films available at follow-up). The results showed that 95% of patients were very satisfied or at least satisfied. Knee score and functional scores were 44 and 54 preoperatively and 90 and 78 postoperatively. Mean range of motion was 116°. On X-ray analysis, the average mechanical femorotibial angle was 179° postoperatively. Survival of the implant for revision was 94.2% at 14 years. We performed 83 re-operations (nine patellar fractures, 14 infections, 12 cases of stiffness and 11 clunck syndromes), including 33 component revisions. Clinical results compared favourably with the literature. This original posterior stabilisation design confirmed the good and excellent results at follow-up. We obtain good range of motion, and no revision was due to polyethylene wear

Background. In this study, we assessed implant survivorship, patient satisfaction, and patient-reported functional outcomes at two years for patients implanted with a customized, posterior stabilized knee replacement system. Methods. Ninety-three patients (100 knees) with the customized PS TKR were enrolled at two centers. Patients’ length of hospitalization and preoperative pain intensity were assessed. At a single time point follow-up, we assessed patient reported outcomes utilizing the KOOS Jr., satisfaction rates, implant survivorship, patients’ perception of their knee and their overall preference between the two knees, if they had their contralateral knee replaced with an off-the-shelf (OTS) implant. Results. At an average of 1.9-years implant survivorship was found to be 100%. From pre-op until time of follow-up, we observed an average decrease of 5.4 on the numeric pain rating scale. Satisfaction rate was found to be high with 90% of patients being satisfied or very satisfied and 88% of patients reporting a “natural” perception of their knee some or all the time. Patients with bilateral implants mostly (12/15) stated that they preferred their customized implant over the standard TKR. The evaluation of KOOS Jr. showed an average score of 90 at the time of the follow up. Conclusion. Based on our results, we believe that the customized PS implant provides patients with excellent outcomes post-surgery. Moreover, a subset of patients with an OTS implant in one knee and a customized PS implant in the other, we observed a trend in patients preferring the customized PS device over their OTS counterparts

Purpose. The purpose of this study was to examine the influence of weight-bearing on the measurement of in vivo wear of total knee replacements using model-based RSA at 1 and 2 years following surgery. Methods. Model-based RSA radiographs were collected for 106 patients who underwent primary TKR at a single institution. Supine RSA radiographs were obtained post-operatively and at 6-, 12-, and 24-months. Standing (weight-bearing) RSA radiographs were obtained at 12-months (n=45) and 24-months (n=48). All patients received the same knee design with a fixed, conventional PE insert of either a cruciate retaining or posterior stabilized design. Ethics approval for this study was obtained. In order to assess in vivo wear, a highly accurate 3-dimensional virtual model of each in vivoTKA was developed. Coordinate data from RSA radiographs (mbRSA v3.41, RSACore) were applied to digital implant models to reconstruct each patient's replaced knee joint in a virtual environment (Geomagic Studio, 3D Systems). Wear was assessed volumetrically (digital model overlap) on medial and lateral condyles separately, across each follow-up. Annual rate of wear was calculated for each patient as the slope of the linear best fit between wear and time-point. The influence of weight-bearing was assessed as the difference in annual wear rate between standing and supine exams. Age, BMI, and Oxford-12 knee improvement were measured against wear rates to determine correlations. Results. Weight bearing wear measurement was most consistent and prevalent in the medial condyle with 0–4% of calculated wear rates being negative compared to 29–39% negative wear rates for the lateral condyle. For the medial condyle, standing exams revealed higher mean wear rates at 1 and 2 years; supine, 16.3 mm. 3. /yr (SD: 27.8) and 11.2 mm. 3. /yr (SD: 18.5) versus standing, 51.3 mm. 3. /yr (SD: 55.9) and 32.7 mm. 3. /yr (SD: 31.7). The addition of weight-bearing increased the measured volume of wear for 78% of patients at 1 year (Avg: 32.4 mm. 3. /yr) and 71% of patients at 2 years (Avg: 48.9 mm. 3. /yr). There were no significant (95% CI) correlations between patient demographics and wear rates. Discussion and Conclusion. This study demonstrated TKA wear to occur at a rate of approximately 10 mm. 3. /year and 39 mm. 3. /year in patients imaged supine versus standing, respectively, averaged over 2 years of clinical follow-up. In an effort to eliminate the effect of PE creep and deformation, wear was also calculated between 12 and 24 months as 9.3 mm. 3. (standing examinations), This value is comparable to wear rates obtained from retrieved TKRs. Weight-bearing exams produced better wear data with fewer negative wear rates and reduced variance. Limitations of this study include: supine patient imaging performed at post-op, no knee flexion performed, and unknown patient activity level. Strengths of this study include: large sample size of a single TKR system, linear regression of wear measurements and no requirement for implanted RSA beads with this method. Based on these results, in vivo volumetric wear of total knee replacement polyethylene can be reliably measured using model-based RSA and weight-bearing examinations in the short- to mid–term. For any figures or tables, please contact authors directly

Introduction. Special high-flexion prosthetic designs show a small increase in postoperative flexion compared to standard designs and some papers show increased anterior knee pain with these prosthesis. However, no randomised controlled trails have been published which investigate difference in postoperative complaints of anterior knee pain. To assess difference in passive and active postoperative flexion and anterior knee pain we performed a randomized clinical trial including the two extremes of knee arthroplasty designs, being a high flex posterior stabilized rotating platform prosthesis versus a traditional cruciate retaining fixed bearing prosthesis. We hypothesised that the HF-PS design would allow more flexion, due to increased femoral rollback with less anterior knee pain than the CR design. We specifically assessed the following hypotheses:. Patients have increased flexion after HF-PS TKA compared to CR TKA, both passive and active. Patients show an increased femoral rollback in the HF-PS TKA as compared to the CR TKA. Patients receiving a HF-PS TKA design report reduced anterior knee pain relative to those receiving the CR TKA. Methods. In total 47 patients were randomly allocated to a standard cruciate retaining fixed bearing design (CR) in 23 patients and to a high-flexion posterior stabilized mobile bearing design (HF-PS) in 24 patients. Preoperative and one year postoperative we investigated active and passive maximal flexion. Furthermore, we used the VAS pain score at rest and during exercise and the Feller score to investigate anterior knee pain. A lateral roentgen photograph was used to measure femoral rollback during maximal flexion. Results. The HF-PS did show a significantly higher passive postoperative flexion; 120.8° (SD 10.3°) vs. 112.0° (SD 9.5°) for the CR group (p=0.004). The active postoperative flexion, VAS-pain score and Feller score did not show significant differences between both groups. Sub analysis with the HF-PS group showed a higher VAS-pain for the patients achieving ≥130° of flexion; 30.5 (SD 32.2) vs. 12.2 (SD 12.5) (p=0.16). The rollback was significantly lower in the CR group compared to the HF-PS group; 4.4 (SD 3.0) vs. 8.4 (SD 2.1). Conclusion. The present study showed a significant higher passive flexion in the Posterior Stabilised-High Flexion mobile bearing compared to a Cruciate Retaining fixed bearing prosthesis. However, this difference disappeared when comparing active flexion. The difference in passive flexion was probably related to a significantly lower rollback causing impingement in the CR prosthesis. No difference in anterior knee pain was found between both groups. However, a suggestion is raised that achieving high-flexion might lead to more patellofemoral complaints/anterior knee pain

Introduction. Maintaining posterior stability in total knee arthroplasty (TKA) may be achieved by using a posterior stabilized TKA, retaining and balancing the posterior cruciate ligament (PCL) using a traditional cruciate-retaining design (CR), or by increasing the sagittal plane conformity of the tibial insert. In the latter case, stability is achieved by the addition of an anterior buildup on the tibial polyethylene creating the so-called “anterior stabilized” (AS) design. We hypothesized that using an AS tibial insert would provide similar function and survivorship as compared to using a more traditional CR bearing when the PCL is either recessed or balanced. Methods. Between 2004 and 2016, 1,731 modular CR TKAs were implanted in 1,509 patients using the same CR TKA design. The diagnosis was osteoarthritis in 98%. 58% of patients were female. Average age of 64.9 years. Within this group, 868 TKAs (50.1%) had a standard CR tibial bearing (3-degree posterior slope and no posterior lip) implanted (CR-S). 480 TKAs (27.8%) had a lipped CR modular tibial bearing (2.5 mm elevated posterior lip) implanted (CR-L). Starting in 2013, 383 TKAs (22.1%) were implanted with an AS modular tibial bearing (9–11 mm anterior lip and a 5 mm posterior lip). If the PCL was considered non-functional or absent, an AS bearing was placed. If the PCL was considered functional, a standard bearing or lipped bearing was used. Clinical and radiographic analysis was performed according to the Knee Society (KS) grading system. The most recent clinical and radiographic evaluation was used for post-operative analysis. The average follow-up in the entire cohort of TKAs was 5.5 years (range 2 to 14.3 years). Kaplan-Meier analysis was used to determine prosthesis survivorship with failure defined as aseptic loosening of the prosthesis (with or without revision) or tibial insert exchange. Results. At final follow-up, there were no significant differences in knee flexion, pain, function, or stair scores. Walking scores were significantly lower in the AS group. Posterior instability was higher in the CR-S group, whereas the manipulation rate was highest in the CR-L group (1.7% versus 1.3% and 0% in the CR-S and AS groups, respectively). Kaplan-Meier survivorship at five years, excluding infection, demonstrated no significant difference between the three groups (CR-S, CR-L, and AS tibial insert groups, 99% 100% and 99% respectively). Conclusion. When the PCL is considered non-functional at operation, the AS insert provided similar final flexion, function, stair score, and five-year survivorship when compared to using the standard and lipped CR tibial insert when the PCL was balanced. Using an ultra-congruent AS dished tibial component appears to be a reasonable option when the PCL is completely released or found deficient at operation. For figures, tables, or references, please contact authors directly

Easier patient positioning and less extensive soft tissue dissection have spurred a trend for anterior instrumentation and fusion for C-spine fracture/ dislocations. We present group of forty-six patients treated over an eighteen month period with an anterior approach. There were no permanent approach related complications, infections, hardware failures or graft displacements. One patient had worsened post-operative neurological findings. One patient required additional posterior stabilization for a missed injury. Two patients were not reducible from the front and required posterior reduction and stabilization followed by anterior instrumentation and fusion. All grafts healed within four months of the operation. The purpose of this study was to assess the efficacy of anterior instrumentation and fusion for Cervical Spine fracture/ dislocations. Over an eighteen month period, forty-six out of fifty-two patients with C-spine injuries requiring surgical treatment were followed prospectively. All patients underwent anterior approaches to stabilize and fuse the unstable segments using tricortical bone grafting and application of an anterior plate (CSLP, Synthes). Thirty-eight patients had single level injuries treated with discectomy and fusion. Two patients had two level discecomies. Six patients underwent corpectomy and fusions for fractures of the vertebral bodies. There were no approach related complications such as recurrent laryngeal nerve injuries, oesophageal perforations, vascular injuries or strokes. One patient deteriorated neurologically. All other patients either improved neurologically or remained with their original findings. Two patients required oral antibiotics for superficial infections at the donor site. There were no spine infections, hardware loosening or graft extrusions. All bone grafts healed within four months both clinically and radiologically. Forty-one patients complained of minor or no pain after four months. Five patients continued to have moderate discomfort. One of these patients had a missed injury above his two-level fusion with gradual progression into kyphosis requiring posterior stabilization. Halo vest immobilization and posterior stabilization for C-spine fracture /dislocations have been the treatment of choice for many surgeons. The low complication and failure rate has spurred on a gradual change towards anterior instrumentation and fusion. Our study very strongly supports this trend. We see little indication for the more invasive posterior approach given our present results

Aims

The aim of this study was to compare the migration of the femoral component, five years postoperatively, between patients with a highly cross-linked polyethylene (HXLPE) insert and those with a conventional polyethylene (PE) insert in an uncemented Triathlon fixed insert cruciate-retaining total knee arthroplasty (TKA). Secondary aims included clinical outcomes and patient-reported outcome measures (PROMs). We have previously reported the migration and outcome of the tibial components in these patients.

Aims

The purpose of this study was to assess mid-term survivorship following primary total knee arthroplasty (TKA) with Optetrak Logic components and identify the most common revision indications at a single institution.

Objectives: The aim of this study was to examine the influence of different prosthesis designs (Deep-Dish (DD) vs. posterior stabilized (PS)) on the patello-femoral pressure. The femoro-patellar pressure depends among other things on the AP stability of the knee joint. The use of DD has been described to be equally applicable with a resected or deficient PCL. Methods: Fresh frozen human knee specimens (n = 8, 7 male, 1 female) underwent testing in a kinematic device simulating an isokinetic knee extension cycle from 120° of flexion to full extension. Knee motion was driven by a hydraulic cylinder applying sufficient force to the quadriceps tendon to produce an extension moment of 31 Nm. The amount of patellofemoral contact pressure and its distribution was measured by means of a pressure sensitive film (Tekscan. ®. , Inc., Boston, USA). Patellar contact pressure was examined first after implantation of a cruciate retaining TKA (Genesis II, Smith& Nephew, Memphis, USA). An 11 mm polyethylene (PE) DD insert was tested before and after resection of the PCL. Finally, the femoral component of the CR TKA was removed and replaced by a posterior stabilized (PS) model repeating measurements with an 11 mm PE inlay. The patella was not resurfaced throughout the whole procedure. A paired sampled t-test was applied for comparison of means and considered significant at p ≤ 0.05. Results: There was no statistical significant difference of patello-femoral peak and mean contact pressures of the DD inlay before and after resection of the PCL. After implantation of the PS TKA peak pressure was significantly lower (Mean: 6.12 ± 2.37 MPa, Range: 10.68 – 3.30 MPa) in comparison with the DD type (7.12 ± 2.53 MPa, 11.94 – 3.55 MPa; p < 0.01) with a preserved PCL. Also the mean contact pressure turned out to be lower with the PS design (p < 0.006; PS: 3.58 ± 1.25 MPa, 5.91 – 2.08 MPa, DD: 4.27 ± 1.34 MPa, 6.66 – 2.18 MPa). The contact area was also significantly smaller with the PS design (p < 0.03, PS: 140.84 ± 40.04 mm2, 188.47 – 65.10 sq mm, DD: 175.97 ± 24.46 sq mm, 222.56 – 142.56 sq mm). After resection of the PCL differences in contact pressures and contact area between DD and PS failed to reach statistical significance although there was an obvious tendency towards lower pressures with the PS-design. Conclusions: The results of this study suggest that a posterior stabilized TKA design reduces the retropatellar peak and mean pressure as well as the contact area in comparison with a deep-dish design when the PCL is preserved. The better reproducible rollback with a PS model could serve as a possible explanation. However, this difference is less pronounced when a DD inlay is applied after resection of the PCL. Nevertheless, a PS rather than a DD design is recommended in the PCL deficient knee

Aims. The introduction of a novel design of total knee arthroplasty (TKA) must achieve outcomes at least as good as existing designs. A novel design of TKA with a reducing radius of the femoral component and a modified cam-post articulation has been released and requires assessment of the fixation to bone. Radiostereometric analysis (RSA) of the components within the first two postoperative years has been shown to be predictive of medium- to long-term fixation. The aim of this study was to assess the stability of the tibial component of this system during this period of time using RSA. Patients and Methods. A cohort of 30 patients underwent primary, cemented TKA using the novel posterior stabilized fixed-bearing (ATTUNE) design. There was an even distribution of men and women (15:15). The mean age of the patients was 64 years (sd 8) at the time of surgery; their mean body mass index (BMI) was 35.4 kg/m2 (sd 7.9). RSA was used to assess the stability of the tibial component at 6, 12, and 24 months compared with a six-week baseline examination. Patient-reported outcome measures were also assessed. Results. The mean maximum total point motion (MTPM) of the tibial component between 12 and 24 months postoperatively was 0.08 mm (sd 0.08), which is well below the published threshold of 0.2 mm (p < 0.001). Patient-reported outcome measures consistently improved. Conclusion. The tibial component of this novel design of TKA showed stability between assessment 12 and 24 months postoperatively, suggesting an acceptably low risk of medium- to long-term failure due to aseptic loosening

Debate has raged over whether a cruciate retaining (CR) or a posterior stabilised (PS) total knee replacement (TKR) provides a better range of movement (ROM) for patients. Various sub-sets of CR design are frequently lumped together when comparing outcomes. Additionally, multiple factors have been proven to influence the rate of manipulation under anaesthetic (MUA) following TKR. The purpose of this study was to determine whether different CR bearing insert designs provide better ROM or different MUA rates. All primary TKRs performed by two surgeons between March 2006 and March 2009 were reviewed and 2449 CR-TKRs were identified. The same CR femoral component, instrumentation, and tibial base plate were consistently used. In 1334 TKRs a CR tibial insert with 3° posterior slope and no posterior lip was used (CR-S). In 803 there was an insert with no slope and a small posterior lip (CR-L) and in 312 knees the posterior cruciate ligament (PCL) was either resected or lax and a deep-dish, anterior stabilised insert was used (CR-AS). More CR-AS inserts were used in patients with less pre-operative ROM and greater pre-operative tibiofemoral deformity and flexion contracture (p < 0.05). The mean improvement in ROM was highest for the CR-AS inserts (5.9° (-40° to 55°) vs CR-S 3.1° (-45° to 70°) vs CR-L 3.0° (-45° to 65°); p = 0.004). There was a significantly higher MUA rate with the CR-S and CR-L inserts than CR-AS (Pearson rank 6.51; p = 0.04). Despite sacrificing or not substituting for the PCL, ROM improvement was highest, and the MUA rate was lowest in TKRs with a deep-dish, anterior-stabilised insert. Substitution for the posterior cruciate ligament (PCL) in the form of a PS design may not be necessary even when the PCL is deficient. . Cite this article: Bone Joint J 2013;95-B, Supple A:129–32

Purpose Of Study. The in vivo evaluation of patellofemoral contact pressures in a posterior stabilized compared to posterior cruciate sacrificing total knee arthroplasty (TKA). Methods. A prospective descriptive non randomized study was performed on 8 patients. A standard approach to a TKA was performed using a balanced gap technique, while the patella was prepared for a resurfacing. The trial components for the posterior stabilized (PS) TKA where inserted including the gas sterilized pressure transducer (a patella button). Soft tissue was approximated and the knee was taken through full range of movement. Patellofemoral pressure was measured and captured continuously through the full range of movement. The posterior cruciate sacrificing (CS) components were inserted into the same patient and the procedure repeated. In addition, anterior translation of the tibia relative to the femur was measured at 90 degrees. The transducer was removed and final components, including a patella resurfacing were inserted. Results. Significantly lower patella femoral pressures were found for PS TKA compared to CS TKA in full flexion [129.0 ± 21.7 N vs. 109.9 ± 32.1 (p = 0.038173)]. The change in patellofemoral pressure between flexion and extension was significantly lower in PS TKA compared to CS TKA [109.0 ± 21.6 N vs. 90.5 ± 32.0 (p = 0.0037690)]. In addition mean anterior translation at 90° flexion in the CS TKA (6.4 ± 3.2 mm) was significantly less than in PS TKA (17.0 ± 2.6) (p = 0.000072). Conclusion. Significantly lower patellofemoral pressures were found in full flexion with PS TKA compared to CS TKA. The change in patellofemoral pressure in a PS TKA compared to CS TKA was also significantly lower. This study provides possible clinical data when considering patella resurfacing. NO DISCLOSURES

Aims

Gram-negative infections are associated with comorbid patients, but outcomes are less well understood. This study reviewed diagnosis, management, and treatment for a cohort treated in a tertiary spinal centre.

Aims

The aim of this study was to perform a systematic review and bias evaluation of the current literature to create an overview of risk factors for re-revision following revision total knee arthroplasty (rTKA).

Aims

The mid-term results of kinematic alignment (KA) for total knee arthroplasty (TKA) using image derived instrumentation (IDI) have not been reported in detail, and questions remain regarding ligamentous stability and revisions. This paper aims to address the following: 1) what is the distribution of alignment of KA TKAs using IDI; 2) is a TKA alignment category associated with increased risk of failure or poor patient outcomes; 3) does extending limb alignment lead to changes in soft-tissue laxity; and 4) what is the five-year survivorship and outcomes of KA TKA using IDI?

The moderator will lead a structured panel discussion that explores how to manage challenges commonly found in the multiply revised knee. Topics covered will include: (1) Exposure in the multiply operated knee (when to use quad snip, tibial tubercle osteotomy, other techniques); (2) Implant removal: Tips for removing stemmed implants; (3) Management of bone loss in multiply operated knees (metal cones/sleeves vs. structural allograft vs. particulate graft); (4) Level of constraint (when to use posterior stabilised, constrained condylar, and hinge) and management of instability in multiply operated knees; (5) Preferred management of infection in the multiply operated knee; (6) The extensor mechanism: Preferred deficient patellar bone management; Preferred extensor mechanism deficiency management; (7) When is it time to convert to a salvage procedure (i.e. fusion, resection arthroplasty, amputation)?; (8) Post-operative management: wound management; knee range of motion

First generation condylar knee replacements suffered from two prominent observations: 1) Difficulty in stair climbing, 2) Limited range of motion (ROM). Improved understanding of knee kinematics, the importance of femoral rollback, and enhanced stability in flexion led to 2 differing schools of thought: Posterior Cruciate ligament retention vs. Posterior Cruciate substitution. The advantages of posterior cruciate substitution include predictable cam-post engagement leading to rollback, predictable ROM, stability during stair climbing, ease of knee balancing regardless of degree of angular deformity, and avoidance of issues such as PCL tightness / laxity at time of index procedure, as well as late ligament disruption leading to late instability. Evolution has shown that human appendages that no longer served a purpose, slowly shrivel up. As we have seen with the appendix, the coccyx, and the erector pili muscles, these vestigial organs no longer are necessary for daily function and are destined for obsolescence. I submit: the PCL in knee arthroplasty IS THE VESTIGIAL ORGAN: not the posterior stabilizing mechanism!

Introduction. Inability to reproduce 6-degrees of freedom (6DOF) kinematics, abnormal “paradoxical” anterior femoral translation and loss of normal medial pivot rotation are challenges associated with contemporary posterior cruciate retaining and posterior stabilized total knee arthroplasty (TKA). The removal of the anterior and/or both cruciate ligaments in CR/PS TKA, leading to significant kinematic alteration of the knee joint, has been suggested as one of the potential contributory factors in patients remaining dissatisfied after TKA. Bi-cruciate retaining (BCR) TKA designs allow preservation of both anterior and posterior cruciate ligaments with the potential to replicate normal knee joint kinematics. Physically demanding tasks such as sit-to-stand (STS), and deep lunging may be more sensitive tools for investigating preserved kinematic abnormalities following TKA. This study aims to compare in-vivo kinematics between the operated and the contralateral non-operated knee in patients with contemporary BCR TKA design. Methods. Twenty-nine patients (14 male; 15 female, 65.7±7.7 years) unilaterally implanted with a contemporary BCR TKA design featuring an asymmetric femoral component and independently designed medial and lateral bearings were evaluated. Mean follow-up time after BCR TKA was 12.7±5.1 months. All patients received a computer tomography (CT) scan from the pelvis to the ankles for the creation of 3D surface models of both knees (BCR TKA and non-operated). Patients performed single leg deep lunges and sit-to-stand under a validated dual fluoroscopic imaging system (DFIS) surveillance. Each patient's 2D dynamic fluoroscopic images, corresponding 3D surface bone models (for contralateral non-operated knee) and computer aided design (CAD) implant models (for the BCR TKA implanted knee) were imported into a virtual DFIS environment in MATLAB. An optimization procedure was utilized to perform matching between the 3D surface bone models and the 2D fluoroscopic image outlines. In-vivo 6DOF kinematics of the BCR TKA knees and contralateral non-operated side were quantified and analyzed. Results. When performing the high-flexion lunge, BCR TKA knees demonstrated less average femoral posterior translation (13±4mm) during terminal flexion when compared to the contralateral non-operated knees (16.6±3.7mm) (p=0.001). Similarly, during STS, less femoral rollback was observed (11.6±4.5mm vs 14.4±4.6mm, p<0.04) in BCR TKA knees. Overall, BCR TKA knees partially reproduced a normal “screw-home” motion, demonstrating reduced internal rotation during several intervals of the cycles for strenuous flexion activities. BCR TKA knees demonstrated less internal rotation during high-flexion lunge (4±5.6° vs 6.5±6.1°, p=0.05). Similarly, during STS, less internal rotation was observed (4.5±6° vs 6.9±6.3°, p=0.04, p=0.02, p=0.01, p=0.02) in BCR TKA knees. Conclusion. The BCR TKA design demonstrated asymmetries in flexion-extension and internal-external rotation, suggesting that in-vivo tibiofemoral kinematic parameters are not fully restored in BCR patients during functionally strenuous activities such as single leg deep lunges and sit-to-stand. Further studies are required to elucidate the importance of patient factors, surgical component orientation and implant designs in optimizing in vivo kinematics in patients with BCR TKA. For figures, tables, or references, please contact authors directly

Introduction: Recent knee prosthesis designs postulate to allow more flexion of the knee without increasing the contact stress on the polyethylene inlay. The study’s purpose was to compare the tibiofemoral contact stress of four different inlay types of a new “high flexion knee prosthesis system under dynamic, physiologic loading conditions in an in vitro test. Thereby, the cruciate retaining and posterior stabilizing designs were compared. Material and Methods: The TriathlonTM system was implanted into 5 knees of fresh frozen human specimens. The prosthesis system is available with a mobile bearing (MCR) or fixed bearing inlay (FCR). In addition, the posterior stabilized design was although tested in the same manner (MPS=mobile bearing and FPS=fixed bearing inlay). After implantation, specimens were mounted for biomechanical testing in a knee simulator. The test mimicked both the speed and resulting moment exerted during a lower limb isokinetic extension test in a range of tibial motion from 120 degrees flexion to full knee extension. The quadriceps force cylinder was force-controlled provided a constant torque on the lower limb of 31 Nm whereby forces of up to 1500 N were recorded. Inlay motion was measured using an ultrasonic tracking system (CMS 100TM, Zebris GmbH; Isny, Germany). The tibiofemoral peak contact stress was measured using resistive ink, 0.1-mm-thin pressure sensors (Tekscan, Boston), measuring 572 points per compartment at 10 Hz. Results: Average maximum peak contact stress was 18.8 (+/−6.6 MPa) at 11.5° flexion for the medial inlay (MCR) and 23 MPa (+/−11.7 MPa) at 119.5 deg for the lateral inlay (MCR). For the FCR we measured 23 MPa (+/−9,6 MPa, medial) at 67.5° and 19.7 MPa (+/−8.2 MPa, lateral) at 119.9° knee flexion. The average maximum contact stress on the MPS inlay was 19 MPa (+/− 12.6 MPa, medial) at 7.5° and 20 MPa (+/− 13.4 MPa) at 120°. For the FPS we measured 20.8 MPa (+/−13.1 MPa, medial) at 40.6° and 19 MPa (+/−11.6 MPa, lateral) at 120° knee flexion. The maximal rotation recorded for the inlay centers was 1.6 ± 1.2 mm at 1.2° knee flexion and 4.3 ± 3.3 mm at 1.3° for the MPS design. Discussion: This in vitro study characterizes the movement of the mobile bearing inlays of the TriathlonTM system on the tibial baseplate under simulated physiologic loading. With the dynamic ultrasonic tracking device the range of motion and internal/external rotation movement can be accurately determined. The results of this study correlated qualitatively to radiographic measurements. Contact pressures seem not to exceed the maximum contact stress of UHMWPE significantly even at high flexion angles up to 120°. The posterior stabilized design showed no significant lower maximum contact stresses than the cruciate retaining design

Background. Patient satisfaction after total knee arthroplasty (TKA) has been lower than after a similar procedure, total hip arthroplasty. Poor subjective outcomes after TKA may be partially explained by abnormal kinematics patterns after TKA. The purpose of this study was to analyse rotational kinematics patterns in knees that had undergone posterior stabilized (PS)-TKA, and to clarify the relationships between rotational kinematics patterns and patient satisfaction, as well as between rotational kinematics patterns and knee function. Materials & Methods. A total of 49 osteoarthritis knees after primary PS-TKA (NexGen LPS-Flex fixed bearing knee system) were included in this study; deformed valgus, severe flexion contractures, and highly unstable knees were excluded. We used a computer navigation system and measured knee kinematics after each surgery was completed. A single investigator gently applied a manual range of motion from full extension to flexion. The angle of the internal rotation of the tibia was measured automatically at 0º, 30º, 45º, 60º, and 90º, along with maximum extension and flexion. We categorized the post-operative rotational kinematics patterns for individual cases, focusing on the initial knee flexion from 0–30º. Type A corresponded to an increased internal rotation angle of the tibia during the initial knee flexion (screw home-like movement). Type B corresponded to an increased external or an unchanged rotation angle of the tibia. We examined the range of motion (ROM) at 6 months after surgery and assessed the 2011 Knee Society Score (2011 KSS) at ≥1 year following surgery. Statistical analysis. The difference between the two groups was compared using a Wilcoxon rank sum test. Analyses were performed with JMP statistical software v8.0 (SAS Institute). A p-value of <0.05 was regarded as significant. Results. The tibia exhibited an average of 5º of internal rotation at initial knee flexion. The type A kinematics pattern achieved a better ROM and functional activity score (2011 KSS) than the type B kinematics pattern. Discussion. Modern TKA implants have been designed to reproduce normal knee kinematics to achieve better patient satisfaction and knee function. However, few reports have described the relationship between the rotational kinematics patterns at initial knee flexion and patient satisfaction. In our study, the type A postoperative rotational kinematics pattern (screw home-like movement) had better ROM and functional activity score than the type B kinematics pattern. The movement toward the internal rotation of the tibia during initial knee flexion might be important in achieving better clinical results after PS-TKA

Flexion instability is a well-defined, though often difficult to diagnose, type of TKA instability. It may also complicate posterior stabilised arthroplasties. It is one of three modes of tibial-femoral instability along with: 1. Varus-valgus or coronal plane instability and 2. Instability in the plane of motion that results from either fixed flexion contracture and buckling or recurvatum and collapse. The issues for correction of coronal instability are generally alignment and either ligamentous balance or constraint. For plane of motion instability it is full extension without hyperextension and restoration of extensor mechanism power. The issues for flexion instability are basically balanced flexion and extension gaps. The diagnosis of flexion instability is made by history and physical examination. These patients, with a more spacious or lax flexion gap, initially do extremely well following surgery, achieving flexion rapidly and comfortably. They progress within months however, to a condition of chronic swelling and tenderness of peri-articular soft tissue, recurrent effusion and a feeling of unease up and down the stairs, as well as getting up out of a chair: anything that stresses the knee in the flexed position. The diagnosis is confirmed by clinical examination. In gross cases, the patient sitting on the edge of the exam table with the legs dangling and flexed at 90 degrees will first of all close the flexion gap, bringing the tibial component into contact with the posterior femoral condyles when they contract the quadriceps muscle. This vertical motion that precedes extension can be observed. Similarly, if the patient is supine, with the knee flexed to 90 degrees, the examiner may grasp the ankle and with a hand under the thigh, distract the flexion gap and then allow it to close. The travel and the clunk can be appreciated. The standard ‘posterior drawer’ test that is appropriate for the non-arthroplasty knee will only be useful for relatively non-constrained, cruciate dependent prostheses. It will not be useful for flexion instability in the posterior stabilised prosthesis. It is useful to perform this distraction maneuver in flexion, during the arthroplasty with trial components in place to confirm that the arthroplasty is stable in flexion. The common maneuver to assess the flexion gap, of internally and externally rotating the femur to detect medial lateral instability in flexion seems to be less accurate. The patients at greatest risk for this complication are those presenting for arthroplasty with a fixed flexion contracture. If a measured resection technique is employed without consideration of correcting the tighter extension gap, when a (relatively thinner) poly insert is selected to achieve full extension, it will not be thick enough to stabilise the larger/normal flexion gap. Flexion instability should not be confused with so-called “mid-flexion” instability, which is a poorly defined and much more subtle, clinical entity that has been described in case reports of revision surgery and the cadaver laboratory. Although more conforming articular polyethylene inserts may resolve this problem, even if revision is performed to a more constrained component, the essence of the solution is revision arthroplasty to balance the flexion and extension gaps

Posterior stabilized (PS) total knee arthroplasty (TKA), wherein mechanical engagement of the femoral cam and tibial post prevents abnormal anterior sliding of the knee, is a proven surgical technique. However, many patients complain about abnormal clicking sensation, and several reports of severe wear and catastrophic failure of the tibial post have been published. In addition to posterior cam-post engagement during flexion, anterior engagement with femoral intercondylar notch can also occur during extension. The goal of this study was to use dynamic simulations to explore sensitivity of tibial post loading to implant design and alignment, across different activities. LifeModeler KneeSIM software was used to calculate tibial post contact forces for four contemporary PS implants (Triathlon PS, Stryker; Journey BCS and Legion PS, Smith & Nephew; LPS Flex, Zimmer Biomet). An average model of the knee, including cartilage and soft tissue insertion locations, created from MRI data of 40 knees was used to mount and align the component. The Triathlon femoral component was mounted with posterior and distal condylar tangency at: a) both medial and lateral condylar cartilage (anatomic alignment), b) at the medial condylar cartilage and perpendicular to mechanical axis (mechanical alignment with medial tangency), and c) at lateral condylar cartilage and perpendicular to mechanical axis (mechanical alignment with lateral tangency). The influence of implant design was assessed via simulations for the other implant systems with the femoral components aligned perpendicular to mechanical axis with lateral tangency. Five different activities were simulated. The anterior contact force was significantly smaller than the posterior contact force, but it varied noticeably with tibial insert slope and implant design. For Triathlon PS, during most activities anatomic alignment of the femoral component resulted in greater anterior contact force compared to mechanical alignment, but absolute magnitude of forces remained small (<100N). Mechanical alignment with medial tangency resulted in greater posterior contact force for deep knee bend and greater anterior force for chair sit activity. For all implants, peak posterior contact forces were greater for activities with greater peak knee flexion. The magnitude of posterior contact forces for the various implants was comparable to other reports in literature. Overall activity type, implant design and slope had greater impact on post loading than alignment method. Tibial insert slope was shown to be important for anterior post loading, but not for posterior post loading. Anatomic alignment could increase post loading with contemporary TKA systems. In the case of the specific design for which effect of alignment was evaluated, the changes in force magnitude with alignment were modest (<200N). Nonetheless, results of this study highlight the importance of evaluating the effect of different alignment approaches on tibial post loading

INTRODUCTION. This study is to determine the response of CRP after TKR surgery, both unilateral and simultaneous bilateral TKR. According to the previously published literature from North America and Europe CRP value peaks on the 1. st. and 2. nd. post-operative day and then gradually comes down to normal by 6–8 weeks post-operatively. AIM. To determine the trend of CRP in Indian patients undergoing TKR, both unilateral and simultaneous bilateral TKR. To see whether it follows the trend in North American and European population and to determine whether there is a difference in the CPR pattern in unilateral versus simultaneous bilateral TKR patients. MATERIAL & METHODS. Twenty six patients were included in this study. 13 patients each had unilateral TKR and simultaneous bilateral TKR. All the patients were operated by a single surgeon and assistant. Patients who had Rheumatoid arthritis and post operative adverse events like urinary tract infection were excluded from this study. All 26 patients were female patients and the mean age in the unilateral group was 67 years and in the simultaneous bilateral TKR group was 73 years. CRP levels were measured pre- operatively on 2. nd. day and 8 weeks. TKR was performed in a standard fashion. Both the groups received standard pre and post operative antibiotic prophylaxis. All patients received a posterior stabilized knee implant (Maxx Freedom Knee). RESULTS. In both the groups CRP level shot up on the 2. nd. post-operative day. Although the rise in CRP level was significantly higher in the simultaneous bilateral TKR group as against the unilateral TKR group. This difference was statistically significant. The CRP level came back to normal in about 39% of unilateral TKR patients at 8 weeks post operatively, while in majority (12 out of 13) of bilateral simultaneous TKR patient it was still elevated at 8 weeks post-op and had not come to normal. DISCUSSION. Macrophages are the important in the development of acute phase response namely CRP. The macrophages are present in the bone and bone marrow and less often in the skeletal muscle. The bone and bone marrow injury happening while performing TKR is responsible for elevation of CRP. Various North-American and European studies have shown that the CRP level increases significantly on the 1. st. postoperative day and the decreases from a peak on the 2. nd. postoperative day, attaining normal value at 6 to 8 weeks after operation. The result of our study are in variance to this published literature. Nearly 39% of our unilateral TKR patients and majority all of our simultaneous bilateral TKR patients did not achieve a normal CRP at 8 weeks after operation. These findings are significant as CRP is often used as a very sensitive indicator of post operative joint infection. Hence we conclude that the Indian TKR patients take longer time for the CRP values to become normal and the published literature regarding the normal levels of CRP in Unilateral TKR should not be extrapolated to simultaneous bilateral TKR group

Introduction. When introducing new joint replacement designs, it is difficult to predict with any certainty the clinical performance of the new designs. Using roentgen stereophotogrammetric analysis (RSA) to evaluate the first two years of follow-up can serve as a predictor of late mechanical loosening for hip and knee prostheses. This prospectively randomized study was designed to evaluate the clinical performance of the Triathlon total knee system and compare the results between the two versions; posterior stabilized (PS) and cruciate retaining (CR). Methods. Sixty patients were consecutively randomized (two patients left the study prior to surgery) to receive either the Triathlon total knee PS (30 patients) or the Triathlon total knee CR (28 patients). All components were cemented. The study was approved by the Ethical Committee for Lund University. All patients met the inclusion criteria. There were no statistically significant differences between the demographics for PS and CR. RSA was set to be the principal evaluation parameter. Patient outcome was assessed by the KSS and KOOS questionnaires. Results. There were no statistically significant differences in rotation or translation around or along the three coordinal axes. Neither were there any differences in the maximal total point motion (MTPM) during the 2-year follow-up (p<0.05). There were no statistically significant differences between the clinical results of both groups when using the KSS and the KOOS scoring system (p<0.05). Discussion. There were no clinically significant differences in the RSA 2-year follow-up data, nor in the clinical scores of KSS and KOOS. The results of this study suggest that there is no major differences between the posterior stabilized system and the cruciate retaining system for the Triathlon total knee neither in clinical nor in predictable long term mechanical performance

Past work in our laboratory identified the generalized effects of TKA on muscle balance, showing a significant change in relative moment generating potential balance favoring flexion and external rotation relative to the normal (intact) knee (for both PCL sparing and posterior stabilized TKA). However, there are no reliable data descriptive of the effect of any single prosthesis. This study hypothesized that using a modern TKA (Smith Nephew Journey) and implantation by a single surgeon in five fresh cadaver specimens would result in change in muscle balance similar to the earlier results for posterior stabilized TKA. Using the tendon excursion-angular motion method (MA = dr/dΘ, r is excursion, Θ is joint angle in radians), moment arms of all muscles at the knee were determined for each of three conditions (intact, ACL-deficient, and prosthesis). The moment arms were then multiplied by the known muscle tension fractions to generate each muscle’s relative moment potential for each specimen across the three conditions. The resultant summed total moment potential was then examined for differences in the flexion-extension (FE) and internal-external (IE) rotation components. There was no significant difference in either FE or IE component for intact versus either the ACL deficient condition (FE, p=0.62, IE, p=0.49) or arthroplasty (FE, p=0.99, IE, p=0.82). TKA agreed more closely with the intact knee. Thus, we reject the hypothesis that a modern TKA (Journey) performs as projected by past generic results, and conclude that modern TKA effectively reconstructs the balance of the intact knee. This improves prospects for rehabilitation following TKA

Many patients who undergo a total knee arthroplasty (TKA) wish to return to a more active lifestyle. The implant must be able to restore adequate muscle strength and function. However, this may not be a reality for some patients as quadriceps and hamstrings muscle activity may remain impaired following surgery. The purpose of this study was to compare muscle activity between patients implanted with a medial pivot (MP) or posterior stabilized (PS) implant and controls (CTRL) during ramp walking tasks. Fifteen patients were assigned to either a MP (n=9) or PS (n=6) TKA operated by the same surgeon. Nine months following surgery, the 15 patients along with nine CTRL patients completed motion and EMG analysis during level, ramp ascent & descent walking tasks. Wireless EMG electrodes were placed on six muscles: vastus medialis (VM), vastus lateralis (VL), biceps femoris (BF), semimembranosus (SM) muscles, gastrocnemius medial head (GM), and gastrocnemius lateral head (GL). Participants completed three trials of each condition. EMG data were processed for an entire gait cycle of the operated limb in the TKA groups, and for the dominant limb in the CTRL group. The maximum muscle activity achieved with each muscle during the level trial was used to normalize the ramp trials. The onset and offset of each muscle was determined using the approximated generalized likelihood ratio. Peak muscle activity (PeakLE), total muscle activity (iEMG), and muscle onsets/offsets were determined for each muscle for the ramp ascent and descent trials. Non-parametric Kruskal Wallace tests were used to test for statistical significance between groups with α=0.05. During the ramp up task, both MP and PS groups had significantly greater PeakLE and iEMG for the hamstring muscles compared to the CTRL, whereas the PS group had significantly greater PeakLE compared with the MP group for the SM muscle. During the ramp down task, both MP and PS groups had significantly greater PeakLE and iEMG for the SM and GL muscles compared to the CTRL. The PS group also had significantly greater iEMG for the BF and VM muscles compared to the CTRL. The MP group had a significantly earlier offset for the SM muscle compared to the CTRL. Stability in a cruciate removing TKA is partially controlled by the prosthetic design. During the ramp up task, the TKA groups compensated the tibial anterior translation by activating their hamstrings more and for a longer duration. The MP group required less hamstrings activation than the PS group. During the ramp down task, TKA patients stiffened their knee in order to stabilize the joint. The quadriceps, hamstrings and GL muscle were activated more and for a longer duration than the CTRL group to protect the tibial posterior translation. The PS group required greater BF and VM iEMG than the MP group. Even if surgery reduced pain, differences in muscle activity exist between TKA patients and healthy controls. The prosthetic design provides some stability to the knee, and the MP implant required less muscle activation than the PS implant to stabilize the knee joint

Introduction. Aseptic loosening of total knee replacements is a leading cause for revision. It is known that micromotion has an influence on the loosening of cemented implants though it is not yet well understood what the effect of repeated physiological loading has on the micromotion between implants and cement mantle. This study aims to investigate effect of physiological loading on the stability of tibial implants previously subjected to simulated intra-operative lipid/marrow infiltration. Methods. Three commercially available fixed bearing tibial implant designs were investigated in this study: ATTUNE. ®. , PFC SIGMA. ®. CoCr, ATTUNE. ®. S+. The implant designs were first prepared using a LMI implantation process. Following the method described by Maag et al tibial implants were cemented in a bone analog with 2 mL of bone marrow in the distal cavity and an additional reservoir of lipid adjacent to the posterior edge of the implant. The samples were subjected to intra- operative range of motion (ROM)/stability evaluation using an AMTI VIVO simulator, then a hyperextension activity until 15 minutes of cement cure time, and finally 3 additional ROM/stability evaluations were performed. Implant specific physiological loading was determined using telemetric tibial implant data from Orthoload and applying it to a validated FE lower limb model developed by the University of Denver. Two high demand activities were selected for the loading section of this study: step down (SD) and deep knee bend (DKB). Using the above model, 6 degree of freedom kinetics and kinematics for each activity was determined for each posterior stabilized implant design. Prior to loading, the 3-D motion between tibial implant and bone analog (micromotion) was measured using an ARAMIS Digital Image Correlation (DIC) system. Measurement was taken during the simulated DKB at 0.25Hz using an AMTI VIVO simulator while the DIC system captured images at a frame rate of 10Hz. The GOM software calculated the distance between reference point markers applied to the posterior implant and foam bone. A Matlab program calculated maximum micromotion within each DKB cycle and averaged that value across five cycles. The implant specific loading parameters were then applied to the three tibial implant designs. Using an AMTI VIVO simulator each sample was subjected to 50,000 DKB and 120,000 SD cycles at 0.8Hz in series; equating to approximately 2 years of physiological activity. Following loading, micromotion was measured using the same method as above. Results. Initial micomotion measurements during DKB activity for ATTUNE. ®. , PFC SIGMA. ®. CoCr, ATTUNE. ®. S+ were 155µm, 246µm, and 104µm, respectively, and following physiological loading were 159µm, 264µm, and 112µm, respectively. While there was statistical significance between the micromotion of implant designs (p<0.05), there was no significance between before and after loading. Conclusion. This study shows there is no significant change in micromotion after approximately 2 years of physiological loading. However, there is a significant difference in micromotion between implant designs

Aims

It is unknown whether gap laxities measured in robotic arm-assisted total knee arthroplasty (TKA) correlate to load sensor measurements. The aim of this study was to determine whether symmetry of the maximum medial and lateral gaps in extension and flexion was predictive of knee balance in extension and flexion respectively using different maximum thresholds of intercompartmental load difference (ICLD) to define balance.

Injury to the spinal cord and kyphosis are the two most feared complications of tuberculosis of the spine. Since tuberculosis affects principally the vertebral bodies, anterior decompression is usually recommended. Concomitant posterior instrumentation is indicated to neutralise gross instability from panvertebral disease, to protect the anterior bone graft, to prevent graft-related complications after anterior decompression in long-segment disease and to correct a kyphosis. Two-stage surgery is usually performed in these cases. We present 38 consecutive patients with tuberculosis of the spine for whom anterior decompression, posterior instrumentation, with or without correction of the kyphus, and anterior and posterior fusion was performed in a single stage through an anterolateral extrapleural approach. Their mean age was 20.4 years (2.0 to 57.0). The indications for surgery were panvertebral disease, neurological deficit and severe kyphosis. The patients were operated on in the left lateral position using a ‘T’-shaped incision sited at the apex of kyphosis or lesion. Three ribs were removed in 34 patients and two in four and anterior decompression of the spinal cord was carried out. The posterior vertebral column was shortened to correct the kyphus, if necessary, and was stabilised by a Hartshill rectangle and sublaminar wires. Anterior and posterior bone grafting was performed. The mean number of vertebral bodies affected was 3.24 (2.0 to 9.0). The mean pre-operative kyphosis in patients operated on for correction of the kyphus was 49.08° (30° to 72°) and there was a mean correction of 25° (6° to 42°). All except one patient with a neural deficit recovered complete motor and sensory function. The mean intra-operative blood loss was 1175 ml (800 to 2600), and the mean duration of surgery 3.5 hours (2.7 to 5.0). Wound healing was uneventful in 33 of 38 patients. The mean follow-up was 33 months (11 to 74). None of the patients required intensive care. The extrapleural anterolateral approach provides simultaneous exposure of the anterior and posterior aspects of the spine, thereby allowing decompression of the spinal cord, posterior stabilisation and anterior and posterior bone grafting. This approach has much less morbidity than the two-stage approaches which have been previously described

Purpose: We hypothesised that independent Notch Trial is essential on same lines as other Component Trials – Femoral, Tibial and Patellar – in posterior stabilised total knee arthroplasty and evolved Notch Trial to visually ascertain adequacy of intercondylar resection and eliminate femoral intercondylar fractures. We undertook a retrospective study to evaluate Notch Trial by the frequency of the need to remove osteophytes or file uneven surfaces in intercondylar resection by using detachable box part of trial femoral component and occurrence of distal femoral intercondylar fractures. Methods & Results: We studied 206 patients, 113 females and 93 males, who underwent consecutive primary posterior stabilised total knee replacements applying Notch Trial between 2000 and 2008 under our team. Outcome Measurements were. frequency of osteophyte removal or filing uneven surfaces in intercondylar resection and. distal femoral intercondylar fractures intraoperatively or on postoperative radiographs. We had to remove osteophytes and file cut surfaces in 183 (88.88%) patients after Notch Trial. We had no distal femoral intercondylar fractures. Conclusions: Notch Trial allows the surgeon to directly visualise and ascertain adequacy and precise fit of femoral notch cut with cam part to ensure press fit femoral component in condylar posterior cruciate substituting total knee replacement. Notch Trial prior to Femoral Component Trial effectively pre-empts intraoperative distal femoral intercondylar fractures. We recommend that Notch Trial should become part of the protocol for cruciate substituting total knee replacement and implants of all companies should have the option of a detachable box component for Notch Trial

In severe destructive spinal infections, with neurological deficit, progressive deformity or uncontrolled sepsis, the mainstay of treatment is surgical debridement with anterior and posterior stabilisation. We retrospectively reviewed 14 patients (11 Male 3 female) with a mean age of 63 (range 38 to 85) who underwent anterior only surgery consisting of an expandable vertebral body cage and a ventrolateral locking plate (Synthes). Organisms included Tuberculosis (7), Staphylococcus (5), E-Coli (1) and Pseudomonas (1). Radiological and functional outcomes were assessed upto 18 months post surgery. Cobb angles were used to measure angular deformity. Good early results in terms of safety, resolution of pain, control of deformity and improvement of neurological deficits was observed. Average blood loss was 633mls (range 300mls to 1500mls) with a mean deformity correction of 23 degrees. Post operative radiological assessment showed the cages to be relatively stable in the under 80 yrs groups (mean loss of correction 15 %). In elderly patients (> 80 yrs) there was significant subsidence leading to a loss of correction (mean 52%) which required stabilisation using vertebral body cement augmentation. In one case, there was implant displacement requiring revision and additional posterior stabilisation. 11 patients showed significant improvement in neurology and 3 patients remained neurologically normal ie Frankel E. We propose assessing severe spinal infections using the spinal trilogy of neurological deficit, deformity and sepsis. Anterior stabilisation using an expandable cage and locking plate alone or with additional vertebral body cement augmentation in elderly patients provides a satisfactory solution for severe destructive spinal infections. It preserves the posterior column and reduces the need for further posterior surgery

Purpose of the study: Several authors have focused attention on the kinematics of total knee arthroplasty. In vitro studies have shown the influence of prosthetic kinematics on wear of the tibial insert. In vivo, investigations are limited for this important parameter. We propose computer algorithm which gives a linear assessment of femur penetration into the tibial insert. The purpose of this work was to test this measurement by radiostereometric analysis (RSA) on pre-worn prosthesis models. Material and methods: A resin plateau was manufactured with four Triatlhon posterior stabilized inserts. Three of these inserts were pre-worn on the medial glenoid; wear varied from 0.8 to 1.2 mm. The wear pattern was controlled by a computer program in order to localize it on a posteromedial gliding band posteriorly to the posterior stabilization implant. A femoral component was implanted on dry bone and loaded on a simulator. RSA images were obtained for each of the plateau. Five series of images were obtained from 0 to 40° flexion. The measurement method consisted in defined a perfect middle plane based on the analysis of tantalum beads embedded in the resin plateau, the to define the point the closest to this plane belonging to the medial condyle. The norm of the normal vector for this plane passing through the lowest point of the femur was the reference. The difference of the norms of the vectors constructed from the healthy plateau and the worn plateaus was defined as penetration of the femur into the tibia insert. The rood mean square (RMS) method was used to measure intraobserver variability and the interclass coefficient of correlation (ICC) was determined. Results and Discussion: Our results were encouraging. 0.8/to 1.12 mm wear was detected with very good accuracy. The data spread was however wide, irrespective of the wear value. The images in flexion of this model provided the most reliable readings. This study is the first offering an approach to wear measurement in vivo. The data spread should be improved by fine tuning the experimental model and the pre-wear pattern. Conclusion: In vivo measurement of TKA wear remains a challenge in clinical medicine. Our work demonstrate the feasibility of using RSA

Purpose: The range of motion after TKA depends on many patient, surgical technique, and implant factors. Recently, high-flexion designs have been introduced as a means of ensuring or gaining flexion after TKA. We therefore evaluated factors affecting postoperative flexion to determine whether implant design influences long-term flexion. Method: We prospectively collected data on patients receiving a primary Genesis II total knee replacement with a minimum of 1-year followup (mean, 5.4 years; range, 1–13 years). We recorded pre – and postoperative outcome measures, patient demographics, and implant design (cruciate retaining [CR, n = 160], posterior stabilized [PS, n = 1177], high-flex posterior stabilized [HF-PS, n = 197]). Results: Backward stepwise linear regression modeling revealed the following factors that significantly affected postoperative flexion: preoperative flexion, gender, body mass index, and implant design. Independent of gender, body mass index, and preoperative flexion, patients who received a HF-PS and PS design implant resulted in 8° and 5° more flexion, respectively, than those who received a CR implant. Based on analysis examining pre-operative flexion categories, patients with low flexion preoperatively (< 100°) were more likely to gain flexion, whereas those with high flexion preoperatively (> 120°) were most likely to maintain or lose flexion postoperatively. Controlling for implant design, patients with high flexion preoperatively (> 120°) were more likely to gain flexion with the HF-PS design implant (HF-PS = 32.0%; PS = 15.1%; CR = 4.5%). Conclusion: In summary, our data demonstrate postoperative range of motion after TKA is related to several factors, confirming the important role of the patient’s preoperative range of motion. In addition, our review suggests knee design and, in particular, the use of a so called “high-flexion” PS polyethylene design may be advantageous in maintaining or improving flexion postoperatively, especially in those patients with good pre-operative range of motion

Purpose of the study: The purpose of this retrospective study was to present the outcomes observed with the Cedior total knee arthroplasty (TKA), and in particular an embedded patellar implant fixed without cement and cemented titanium backed base plate with a press fit stem. Material and methods: From January 1993 to December 1996, 155 TKA were implanted in 143 patients for degenerative disease of the knee joint. At last follow-up, 55 patients had died, 28 were lost to follow-up 14 were contacted by phone, and 46 were reviewed clinically. Mean age was 62 years (62–80), BMI: 29.9 (22.6–38.2). Mean follow-up was 12 years (10–13). Posterior stabilised implants were used for 33% of the knees and the posterior cruciate was preserved in 67%. For all knees, the thickness of the polyethylene was > 6mm. Outcome was assessed clinically with the IKS, WOMAC, and Charnley scores and radiographically on the basis f lucent lines, osteolysis, and residual misalignment as measured on the standard films and goniometry. Survival was determined with the Greenwood method. Results: Two patients (2 posterior stabilised TKA) with residual varus > 6 (> 15 preoperatively) were revised for loosening. At last follow-up, the postoperative IKS was 164, the WOMAC 28. Two patients were dissatisfied. Radiographically residual alignment was less than 3 in 56%, 3 to 6 in 41% and > 6 in 3%. For the femur, there were two lucent lines in a single zone. For the tibia, six lines in zone 7, none around the stem. For the patella, two implants presented significant asymptomatic osteolysis and there were two spontaneous (5 and 8 years) and asymptomatic fractures. Survival was 98.1±4.6% for revision and 96.2±6.9% for aseptic loosening. Discussion: Our results are comparable with 10-year outcomes published in the literature where the survival has ranged from 92% to 99%. The titanium back cemented under the bas without cementing the sanded stem provides satisfactory results. The two loosening occurred for a residual varus > 6. The embedded, non-cemented patellar implant gave satisfactory results but the two cases of osteolysis led us to propose cementing

Study Aim. Femoral components used in total knee arthroplasty (TKA) are primarily designed on the basis of kinematics and ease of fixation. This study considers the stress-strain environment in the distal femur due to different implant internal geometry variations (based on current industry standards) using finite element (FE) analyses. Both two and three dimensional models are considered for a range of physiological loading scenarios – from full extension to deep flexion. Issues associated with micro-motion at the bone-implant interface are also considered. Materials and methods. Two (plane strain) and three dimensional finite element analyses were conducted to examine implant micro-motions and stability. The simple 2D models were used to examine the influence of anterior-posterior (AP) flange angle on implant stability. AP slopes of 3°, 7° and 11° were considered with contact between bone and implant interfaces being modeled using the standard coulomb friction model. The direction and region of loading was based on loading experienced at full extension, 90° flexion and 135° flexion. Three main model variations were created for the 3D analyses, the first model represented an intact distal femur, the second a primary implanted distal femur and the third a distal femur implanted with a posterior stabilising implant. Further each of the above 3D model sets were divided into two group, the first used a frictional interface between the bone and implant to characterise the behavior of uncemented implants post TKA and the second group assumed 100% osseointegration had already taken place and focused on examining the subsequent stress/strain environment in the femur with respect to different femoral component geometries relative the intact distal femur model. Results and Discussion. Analyses indicate a trend relating the slope of the anterior-posterior (AP) flange to implant loosening at high flexion angles for uncemented components. Once cemented, this becomes less important. Results from the 3D analyses show that the posterior stabilising implant causes stress concentrations which can lead to bicondylar fatigue fracture. All femoral components cause stress shielding in cancellous bone particularly when they are fully bonded. Investigations into implant micromotion show that revision implants with box sections provided more resistance to micromotion than the pegged primary implants. However for the gait cycle tested the maximum recorded micromotion of both implants was well within acceptable levels for osseointegration to occur

Purpose of the study: We analysed the clinical and radiographic outcomes of 113 cemented total knee arthroplasties (TKA) with resurfaced patella implanted in 83 patients with rheumatoid arthritis who were reviewed 1 to 12 years after implantation. Mean follow-up was 5.86 years. All implants were posterior stabilised (HLS) implanted by one operator using the same procedure. Material and methods: One hundred seventy-two rheumatic arthritis patients underwent TKA from 1996 to 2007. At last follow-up, 68 could not be contacted, 11 had died, 9 declined review. The review was conducted in 2008 for 83 patients, 113 TKA. Female gender predominated (86.4%) and 29 patients (32.6%) had two TKA. Mean age at revision was 67.6 years. Results: Seventy patients (84.4%) were satisfied or very satisfied with their prosthesis. The knee score (IKS) improved from 31.58 (0–63) preoperatively to 86.21 (59–99) postoperatively; the function score (IKS) improved from 31.7 (0–100) preoperatively to 77.12 (0–100) postoperatively. The improvement was significant for both scores. Men preoperative flexion was 97 (35–125) versus 112.1 (30–130) postoperatively. Ten knees presented anterior pain at revision (8.8%). The postoperative femorotibial mechanical angle was 180.72 (173–192). The mean femoral mechanical angle was 91.3 (78–99); the mean tibial mechanical angle was 89.4 (52–110). Men postoperative patellar height was 0.79 (0.24–2) measured with the Blackburn index. The patella was centred for 87.6% (99 knees) and subluxated laterally for 12.1% (14 knees). There were no loosening. Two arthroplasties had to be revised surgically (1.8%): one for infection (two-phase replacement with a hinged prosthesis) and one for patellar fracture treat by osteosynthesis. Two patients developed a postoperative phlebitis (2.4%). Discussion: This study demonstrates the good mid-term outcomes achieved with a cemented posterior stabilised TKA in patients with rheumatoid arthritis. These results are nevertheless slightly less satisfactory than with TKA implanted for degenerative disease: this might be explained generally by disease-related impact on the functional result. Prosthetic surgery of the knee remains the treatment of choice for advanced arthritic degeneration

Purpose: The literature regarding the outcome of total knee arthroplasty following distal femoral varus osteotomy is limited. The largest published series to date of eleven such patients suggested that medio-lateral constrained implants are commonly required as ligament balancing is difficult. This study presents mid-term outcomes of patients treated with total knee arthroplasty following distal femoral varus osteotomy at a single center. Method: Twenty-two consecutive distal femoral varus osteotomies (21 patients) converted to total knee arthroplasties were reviewed at a mean follow-up of five years (range, two to 14 years). The mean duration between osteotomy and conversion to arthroplasty was 12 years (range, three to 21 years). In 14 patients (15 knees) the underlying etiology for the femoral osteotomy was primary knee osteoarthritis with valgus deformity, while in seven patients the procedure was performed to unload a fresh osteochondral allograft of either the lateral tibia (five patients) or femur (two patients). It is the authors’ routine to use posterior stabilized implants were used in all total knee arthroplasty surgeries. Femoral stems were used in six knees in which the bone quality was clinically determined by the surgeon to be sufficiently deficient to predispose to periprosthetic fractures, while the remaining sixteen knees were treated with unstemmed components. Modified knee society scores were used to evaluate the clinical outcomes preoperatively and at most recent follow-up. Results: The mean knee society knee and function scores in surviving knees improved from 50 points (range, 10 to 75 points) and 50 points (range, 30 to 70 points) pre-operatively, to 91 points (range, 67 to 100 points) and 64 points (range, 50 to 70 points) at final follow-up, respectively. The mean arc of motion improved from 94 degrees (range, 70 to 115 degrees) to 114 degrees (range, 90 to 130 degrees). Two patients underwent revision arthroplasty for polyethylene wear and component loosening at eight and 11 years following the index arthroplasty, respectively. There were no fractures, infections or wound complications. Conclusion: Total knee arthroplasty following distal femoral varus osteotomy reliably decreases pain and improves knee function. Standard posterior stabilized components provide satisfactory stability after appropriate ligamentous balancing, without the need for stemmed or highly constrained components in the majority of patients

Introduction. Mobile-bearing TKRs allow some axial rotation and may provide a more natural patellar movement. The aim was to compare patellar kinematics among the normal knee, fixed-bearing and mobile-bearing TKR. Methods. Optical computer navigation (Brainlab) was used to track the position of the femur, tibia and patella in 9 whole lower extremities (5 fresh cadavers) in the natural knee, in the same knee with the trial components of a posterior stabilised fixed-bearing TKR (FB) (Sigma PFC, Depuy) and a posterior stabilised mobile-bearing TKR (MB) (Sigma RP Stabilised). The patellae were not resurfaced. Values: mean+/−one standard deviation. Statistical analysis: two tailed paired Student's T-test. Results. M/L shift: There was a tendency for the patella to track 2mm more laterally with a FB or MB TKR compared to the natural knee, but this did not reach significance. Tilt: The patella in the natural knee tilted progressively laterally from extension to flexion, plateauing at 50° of flexion (20°: 1.9+/−2.7°, 40°: 5.6+/−5.4°, 60°: 6.2+/−6.4°, 80°:6.5+/−7.3°, 90°: 6.4+/−7.7°). With a FB or MB TKR the patellae also tilted laterally up to 50 degree of flexion, but then started to tilt back medially, reaching the neutral position at 90° again. There was no difference between the FB and MB TKRs. (Fixed bearing: 20°: 2.5+/−7.2° p=0.30, 40°: 3.7°+/−6.5° p=0.15, 60°: 3.1+/−5.8° p=0.02, 80°:1.2+/−6.5° p=0.001, 90°: 0.3+/−7.2° p=0.001, Mobile bearing: 20°: 0.3+/−5.5° p=0.27, 40°: 3.6+/−5.2° p=0.08, 60°: 2.1°+/−5.8 p=0.01, 80°: 0.2+/−6.8 p=0.003, 90°: -0.6+/−7.3 p=0.002; vs. natural). Trochlea position: The centre of the patellar groove of the femur component was more lateral than the trochlea by 2-5mm, it also extended 10mm further proximally. Conclusion. There are kinematic differences in patellar tracking between the natural knee and a FB/MB TKR. Compared to the FB TKR the patellar kinematics of the MB TKR is not more natural

We analysed the clinical and radiographic results after total knee arthroplasty in the valgus knee. Thirty six knees in 27 patients with a valgus alignment of more than 10 degrees of femorotibial angle underwent TKA. The average followup period was 7 years(range 1 to 14 years). Eighteen knees were implanted with a cruciate retaining prosthesis, 17 knees with a posterior stabilized prosthesis, and one knee with a constrained condylar prosthesis. In knees with a preoperative 15 degrees or greater femorotibial angle, the posterior stabilized prosthesis were necessary in 85%. Medial parapatellar approach was used in 27 knees with a preoperative valgus 20 degrees or lesser femorotibial angle. With 20 to 29 degrees valgus, medial parapatellar approach was used in 5 knees and lateral parapatellar approach in 2 knees. With 30 degrees or greater valgus, lateral parapatellar approach was used in 2 knees. The mean postoperative Hospital for Special Surgery knee scores were 89.5 points. Postoperative range of motion averaged 114.4 degrees. Postoperative alignment averaged 6.5 degree valgus. Radiolucent line or loosening was not seen in any knee. There were two deep infections in patients whose preoperative femorotibial angle was greater than valgus 20 degrees using lateral parapatellar approach. Clinical and functional results after TKA in the valgus knee were similar to those in varus knee. But, prevention of deep infection in patients with marked valgus angle was important, especially using lateral parapatellar approach. A more constrained prosthesis was frequently used in more significant valgus deformity. In patients with severe valgus deformity needing lateral capsular release frequently, lateral parapatellar capsular approach was more reasonable than medial parapatellar approach to avoid medial and lateral capsular release simultaneously

The moderator will lead a structured panel discussion that explores how to manage challenges commonly found in the multiply revised knee. Topics covered will include: (1) Exposure in the multiply operated knee (when to use quad snip, tibial tubercle osteotomy, other techniques); (2) Level of constraint (when to use posterior stabilised, constrained condylar, and hinge) and management of instability in multiply operated knees; (3) Management of bone loss in multiply operated knees (metal cones/sleeves vs. structural allograft vs. particulate graft); (4) Preferred management of infection in the multiply operated knee; (5) When is it time to convert to a salvage procedure (i.e. fusion, resection arthroplasty, amputation)?

Introduction. Increased long-term survival of TKA is becoming more important. Several studies have confirmed that optimal positioning and alignment of prosthetic components is crucial for the best long-term results. Therefore, the purpose of the current study was to compare the postoperative alignment and sizing of femoral prosthesis among patients performed by 3 different navigation systems. Methods. Twenty patients who underwent primary TKA (E. motion; B. Braun Aesculap, Tuttlingen, Germany) using a CT-free navigation system (OrthoPilot v 4.2) by modified gap technique were enrolled in this study. The results of this study group were retrospectively compared with those in a control group of 20 matched-paired posterior stabilized TKAs (Triathlon;Stryker; Mahwah, NJ, USA) which were using another CT-free navigation system (Stryker Navigation System) by measured technique and 20 matched-paired posterior stabilized TKAs (Press-fit Condylar prosthesis; DePuy, Tokyo, Japan) using CT-based navigation system (VectorVision) by measured technique. Several parameters were evaluated for each patient using Athena Knee (Softcube Co, Ltd. Osaka, Japan), 3-D image-matching software. The coronal component angles and sagittal component angles were measured in relation to mechanical axis (MA). In addition, axial femoral component angle was measured in relation to surgical epicondylar axis (SEA) and axial tibial component angle was measured in relation to Akagi line. Results. (Coronal plane alignment). The coronal femoral component angle (varus) was 1.3° ± 2.7° in the Orthopilot group, 1.1 ± 1.5° in the stryker group and 0.21° ± 2.2°in VectorVisioin group with no sigificant difference. The coronal tibial component angle (varus) was 0.7° ± 2.0° in the Orthopilot group, −0.50° ± 1.4° in the stryker group and −1.0° ± 1.2° in VectorVision group with no significant difference. (Sagittal plane alignment). The sagittal femoral component angle (flexion) was 2.7° ± 2.2° in the Orthopilot group, 3.3° ± 2.4° in the stryker group and −0.2° ± 2.9°in VectorVisioin group. The sagittal femoral component angle in VectorVison group is significantly smaller than that in the Orthopilot group and that in the Stryker group. The sagittal tibial component angle (posterior slope) was 4.7° ± 1.9° in the Orthopilot group, 2.6° ± 1.5° in the stryker group and 2.8° ± 1.4° in VectorVision group. The posterior slope was aimed at 5°in Orthopilot group and 3°in stryker group and VectorVision group. Accuracy among 3 groups is no significant difference. (Axial component angle). The axial femoral component angle (external rotation) was 2.2° ± 1.9° in the Orthopilot group, 1.2° ± 1.5° in the stryker group and −0.9° ± 2.0°in VectorVisioin group. The axial femoral component angle in Orthopilot group was significantly more external than that in the stryker group and that in the VectorVision group. The axial tibial component angle (external rotation) was 2.4° ± 5.0° in the Orthopilot group, 2.6° ± 5.5° in the stryker group and 2.0° ± 4.2° in VectorVision group with no differnence. Discussion and Conclusion. We performed primary TKA by 3 different navigation systems and analyzed alignment of component. Accurate alignment was obtained in all 3 different navigation systems. However surgeons should take into account the features in each navigation

In patients with previous patellectomy the optimal constrained implant is not well understood. Previous outcome studies have shown contradictory results. There interpretation is limited by small number of patients, included primary and revision implants or involved a heterogeneous group of different constraint implants. We performed retrospective match controlled analysis of a posterior stabilised primary total knee arthroplasty in forty-two patients who had previous patellectomy. There were nineteen male and twenty-three female patients. The average age of patients at the time of surgery was fifty-nine years (range from forty-one to seventy-four years). The average time from patellectomy to total knee arthroplasty was seventeen years (range from one to thirty-four years). The average duration of follow-up was 5.3 years with minimum two years follow up (range from two to sixteen years). The control group was matched by age, sex, prosthesis type and surgeon. We used the student-t test to compare the outcome measurement. Preoperatively, the patellectomy and control groups were not significantly different in terms of Knee Society clinical and functional scores or range of motion. Postoperatively clinical component of the knee society score had a significant difference (p< 0.05) however the functional part of the knee society score didn’t (p> 0.05). In patellectomy group the postoperative clinical and functional score were equal to seventy and fifty-eight respectively. The average clinical component of knee society score in the patellectomy group was twelve points (SE=4.8) lower compare to the knee with intact patella. The patellectomy group also had higher extension lag and poorer extension (higher flexion contracture) at the most recent follow up (p< 0.05). This study demonstrated the outcome of the largest series of primary total knee arthroplasty with posterior stabilised implant in patient with previous patellectomy. The outcome of surgery was significantly improved but not as good as the knee with intact patella especially the function of the extensor mechanism

The moderator will lead a structured panel discussion that explores how to manage challenges commonly found in the multiply revised knee. Topics covered will include: (1) Exposure in the multiply operated knee (when to use quad snip, tibial tubercle osteotomy, other techniques); (2) Implant removal: Tips for removing stemmed implants; (3) Management of bone loss in multiply operated knees (metal cones/sleeves vs. structural allograft vs. particulate graft); (4) Level of constraint (when to use posterior stabilised, constrained condylar, and hinge) and management of instability in multiply operated knees; (3) Management of bone loss in multiply operated knees (metal cones/sleeves vs. structural allograft vs. particulate graft); (5) Preferred management of infection in the multiply operated knee; (6) The extensor mechanism: Preferred deficient patellar bone management; Preferred extensor mechanism deficiency management; (7) When is it time to convert to a salvage procedure (i.e. fusion, resection arthroplasty, amputation)?; (8) Post-operative management: wound management; knee range of motion

There exists a variety of options for a medial compartment knee with osteoarthritis, specifically a unicompartmental knee, high tibial osteotomy, and total knee arthroplasty. This surgeon prefers a rotating platform posterior stabilised total knee to the unicompartmental knee. Unicompartmental knee arthroplasty (UKA) in younger patients is being performed with increasing frequency. While UKA is a powerful marketing tool because of its minimally invasive nature and quality of knee function that is superior to the total knee arthroplasty (TKA), it has tremendous drawbacks. These include: the selection criteria is very specific and the number of patients that fit in that category is small, there is a steep learning curve for the surgeon to perfect the technique, higher failure due to wear and loss of fixation, and unexplained pain. Based on level 1 and 2 evidence available it is not justified to do more UKAs at present when the results of a TKA are so successful

Hypothesis: 1. Increased wear results from modularity. 2. Modification of the patello-femoral articulation will decrease patellar fractures. Materials & Methods: A prospective comparison of 100 consecutive Non-modular Insall Burstein Posterior Stabilized (IBPS) knee prostheses (1986–1989) with 100 consecutive modular IBPS II knee replacements (1989–1990). No patient was lost. Results: IBI: Nine re-operations of which 6 were complete revisions: two for sepsis, one for tibial loosening, one for patellar wear and two for undiagnosed pain. Of seven patellar fractures, five required surgery. IBII: Nineteen re-operations of which six were complete revisions: two for sepsis, one for tibial loosening from catastrophic osteolysis, two for instability and one for stiffness. There were no revisions for patellar complications. Of 12 non-revision re-operations, two were for patellar fractures, three for dislocation of the posterior stabilized mechanism and one for failure of the modular locking mechanism. Six knees suffered patellar “clunks” treated arthroscopically. Discussion: The femoral component patellar groove was smoothed and the posterior stabilized mechanism was relocated on the IB II. This increased motion and decreased patellar fractures but caused scar on the quadriceps tendon to “clunk” and lead to dislocations of the “spine and cam”. All failures occurred in the first five years. Clinical Relevance: Specific patellar problems were improved with design modifications. New problems have been addressed and long-term survival has not been compromised by modularity

Introduction The aim of this study was to examine the flexion stability of posterior stabilised (PS) compared with deep dished (DD) tibial inserts in PCL sacrificing total knee arthroplasty using posterior stress radiography. Methods Kneeling posterior stress radiographs at 90° of flexion were taken pre and post-operatively in 36 knees undergoing primary arthroplasty with PCL resection (26 DD and 10 PS implants). Sagittal plane tibial translation was measured. Results The deep dish inserts all showed posterior displacement (mean: −5.1 mm, range: −2 to −12 mm). The posterior stabilised implants were all displaced anteriorly (mean: +6.7 mm, range: +3 to +12 mm). The difference in translation was highly significant (P< 0.0001). There was a strong correlation between implant and position of the tibia (R = 0.86). In seven patients comparison was possible between a DD component in one knee and a PS implant in the other. There was a mean post-operative side to side difference of 11 mm (range: 5 to 21 mm). Conclusions This study discriminates between two implant types on stress x-rays. The posterior tibial displacement in the DD group suggests that this implant does not provide enough posterior flexion stability to compensate for the PCL resection. The anterior translation in the PS group has implications for the design and wear of the post as well as advice to patients about possibly avoiding kneeling in this PS design

Introduction: Mobile bearing TKA systems have drawn great attention as an alternative solution for the limitations of fixed bearing designs. Recently rotating platform posterior stabilized (RP-PS) was developed to take advantage of the benefits originating from the design features of the traditional rotating platform mobile bearing system and the traditional posterior stabilized fixed bearing system with post and cam mechanism. Despite its theoretical advantages, the clinical outcomes of TKAs with RP-PS mobile bearing system remain to be determined. In theory, compared to fixed bearing systems, clinical performances of mobile bearing knees may be more sensitive to the rehabilitation status due to its relatively small constraint by the prostheses. Therefore, the clinical outcomes can be vary with the follow-up periods. This study was conducted to compare the longitudinal clinical outcomes of TKAs with a RP-PS mobile system and with a floating platform mobile bearing system. Methods: 163 TKAs with one of two mobile bearing systems (E.motion-FP and E.motion-PS: B.Braun-Aesculap, Tuttlingen, Germany) were included in this study. All surgeries were performed by a single surgeon using a computer assisted navigation system (Orthopilot, B.Braun-Aesculap). Clinical outcomes evaluated at 6 months, 12 months, and 24 months were compared between the 70 knees with E.motion-FP and the 93 knees with E.motion-PS. Radiographic measurements of limb alignment and implant positioning showed no significant differences between the two groups. Results: Compared to TKAs with the FP prosthesis, TKAs with the RP-PS prosthesis had greater maximum flexion (128.9 vs. 135.3, p = 0.001) and tended to be more satisfactory (satisfaction level: 3.4 vs. 3.1, p = 0.052). The other clinical outcome scales (AKS knee and function, PF, WOMAC, and SF-36) showed comparable results. No failures were found in both groups. Conclusion: We found that TKAs with the RP-PS mobile bearing system have greater maximum flexion and patient satisfaction than TKAs with the FP mobile bearing system. The long term benefits 2009

We have reviewed our experience in managing 11 patients who sustained an indirect sternal fracture in combination with an upper thoracic spinal injury between 2003 and 2006. These fractures have previously been described as ‘associated’ fractures, but since the upper thorax is an anatomical entity composed of the upper thoracic spine, ribs and sternum joined together, we feel that the term ‘fractures of the upper transthoracic cage’ is a better description. These injuries are a challenge because they are unusual and easily overlooked. They require a systematic clinical and radiological examination to identify both lesions. This high-energy trauma gives severe devastating concomitant injuries and CT with contrast and reconstruction is essential after resuscitation to confirm the presence of all the lesions. The injury level occurs principally at T4–T5 and at the manubriosternal joint. These unstable fractures need early posterior stabilisation and fusion or, if treated conservatively, a very close follow-up

The Genesis II total knee prosthesis was a successor to the Genesis I TKR in which three degrees of external rotation was built into the femoral component to improve patellofemoral tracking and eliminate rotational incongruity. The midterm (minimum five year) results of three hundred and forty-three Genesis II cemented components were reviewed in three hundred and twenty-four patients. Kaplan-Meier survivorship was 98% at a mean 7.6 years. The focus of this study was to analyze the minimum five- year results of patients receiving either a cruciate-retaining, posterior stabilizing, or mobile bearing Genesis II TKR. Further analysis was performed to delineate differences between subsets of this population. Data from a consecutive series of three hundred and twenty-four patients receiving three hundred and sixty-seven Genesis II TKR’s between February 1996 and July 1999 was collected. Patients were evaluated pre-operatively, at six weeks, three months, six months and annually thereafter, using the Knee Society Clinical Rating System and the Western Ontario MacMaster Osteoarthritis Index. A Kaplan-Meier Survivorship was performed on the consecutive series. Statistical analyses were used to delineate significant differences between subsets of patients. There were three hundred and sixty-seven procedures (one hundred and sixty-nine cruciate-retaining, one hundred and sixty-six posterior stabilized and six mobile bearing designs) performed on three hundred and twenty-four patients. At the time of evaluation, forty-five (13%) patients were deceased, twenty-four (7%) patients were unavailable for evaluation and nine (2%) knees had been revised. A 98% implant survivor-ship was calculated at a mean time of 7.6 years. These are the first mid-term (minimum five year) clinical results of the Genesis II TKR, which continues to function well. Kaplan-Meier survivorship was 98% at a mean 7.6 years

Introduction. The aim of this study was to evaluate the effects of posterior tibial slope (PTS) and posterior condylar offset (PCO) on patient-reported pain and function one year after TKA. Methods. A total of 500 patients from 11 clinics in 6 countries were enrolled into a prospective, multicenter study. All patients were indicated for primary TKA for OA and received components from a single manufacturer. All liners were made from vitamin-E stabilized, highly crosslinked (95 kGy) polyethylene; 54.7% were posterior stabilized (PS) and the remaining were cruciate-retaining. The Knee Injury and Osteoarthritis Outcome Score (KOOS) was administered at the one-year follow-up visit. The KOOS pain and activities in daily life (ADL) sub-scores were dichotomized and served as the primary outcomes. Dichotomization was done with the patient acceptable symptom state (PASS), defined by previous studies as the value of the PROM above which patients deem their state as acceptable (84.5 points for KOOS pain and 83.0 points for KOOS ADL). Plain lateral radiographs were taken and assessed for PTS (Figure 1) and PCO (Figure 2). PTS was categorized as above (excessive flexion), within (ideal), or below (extension) the safe zone of 0° − 7° of flexion. PCO increases or decreases of greater than 3mm were compared against no change (≤ 3mm). Each of the two sagittal positioning metrics was tested against the KOOS pain and ADL PASS at one year. Results. 396 patients (80.3% of eligible) had completed the one-year visit. A total of 297 (75%) achieved the PASS in KOOS pain and 277 (70%) achieved the PASS in KOOS ADL (Figure 3). PTS was closely associated with the likelihood of achieving the PASS in KOOS pain (p < 0.001) and ADL (p = 0.005) in univariate tests (Kruskal-Wallis). It was also independently predictive of achieving the PASS in multivariable models controlling for sex, body mass index, preoperative health state, and age. In a binary logistic regression for achieving the PASS in KOOS pain, a PTS < 0° (extension) was 6.3 times less likely to achieve the PASS compared to the ideal PTS (0°–7° of flexion) (p=0.004; OR=0.16). Overly flexed tibial components (>7°) were equally likely to achieve the PASS in KOOS pain as components with an ideal PTS (p=0.091). A separate model assessing independent predictors of achieving the PASS in KOOS ADL, patients with extension were 4.8 times less likely to achieve the PASS compared to those with an ideal PTS (p=0.012; OR=0.21), while patients with excessive flexion were equally likely to achieve the PASS in KOOS ADL as patients with an ideal PTS (p=0.077). When considering the patients with a PTS > 7° (excessive flexion), PCO decrease was associated with a lower chance of achieving the PASS in KOOS ADL (p = 0.022). When considering the patients with a PTS < 0° (extension), PCO increase was associated with a lower chance of achieving the PASS in KOOS pain (p = 0.031). Conclusions. The most influential sagittal positioning parameter affecting patient outcomes at one year after TKA was PTS. PTS had a significant, independent effect on all PROMs one year after TKA. Surgeons should be more cautious to avoid tibial component extension rather than excessive flexion. We recommend replicating the native PCO and targeting a PTS of 0°–7° of flexion. For any figures or tables, please contact authors directly

Introduction. Clinical observations suggest mid-flexion instability may occur more commonly with rotating platform (RP) total knee arthroplasty (TKA), including increased revision rates and patient-reported instability and pain. We propose that increased gap laxity leads to liftoff of the lateral femoral condyle with decreased conformity between the femoral component and polyethylene (PE) insert surface leading to PE subluxation or dislocation. The objectives of this study were to define “at risk” loading conditions that predispose patients to PE insert subluxation or spinout, and to quantify the margin of error for flexion/extension gap laxity in preventing these adverse events under physiologic loading conditions. Methods. Biomechanical testing was performed on six fresh frozen cadaveric knees implanted with a posterior stabilized RP TKA using a gap balancing technique. Rotational displacement and torque were measured over time, while stiffness, yield torque, max torque and displacement were calculated using a post-processing, custom MatLab code. Revision with varying size femoral components (size 3–6) and PE insert thicknesses (10–15mm), by downsizing one step, were used to create a spectrum of flexion/extension gap mismatch. Each configuration was subjected to three loaded testing conditions (0°, 30° and 60° flexion) in balanced and eccentric varus loading, known to represent daily clinical function and “at risk” circumstances. Results. PE insert rotational instability was primarily determined by conformity and contact area between the femoral condyle and the upper surface of the PE insert. In this RP design, contact area is known to decrease with flexion greater than 35°, which predisposed to abnormal motion of the femur on PE insert (Figure 1). Under all flexion/extension gap testing conditions, PE insert rotational displacement significantly decreased with increasing knee flexion (differences ranged from 0.42 to 1.01cm, p<0.05), confirming that decreased conformity allows unintended motion to occur on the upper rather than the lower insert surface, as kinematically designed. This decrease in insert rotation was further exacerbated with eccentric medial-sided loading (differences ranged from 0.77 to 1.18cm, p<0.05). Yield torque (19.66±6.79N-m, p=0.033) and max torque (19.76±5.93N-m, p=0.014) significantly increased with increasing flexion from 0° to 60° under gap balanced conditions. Yield torque significantly decreased with greater flexion gap laxity at 60° of flexion (−24.82±5.96N-m, p=0.004). The depth of the lateral PE insert concavity (1.7–3.6mm) varied with insert size and thickness and determined femoral condylar capture. The lateral insert concavity defines a narrow margin of error in flexion/extension gap asymmetry leading to rotational insert instability, especially in smaller sized knees (size 3) where the jump height (1.7mm) is less than the insert sizing increment of 2.5mm. Conclusions. Contact area is known to decrease with flexion greater than 35° in this TKA-RP design. Flexion gap laxity further increased the risk of unintended top-side rotation of the femur on the insert, especially with increasing flexion and smaller components. In RP-TKA, in addition to medial-lateral gap symmetry and flexion-extension balance, a snug flexion gap with less than 2mm lateral laxity is critical to avoid insert instability and condylar escape with insert subluxation. For any figures or tables, please contact authors directly