Aims

The primary objective of this study was to compare the five-year tibial component migration and wear between highly crosslinked polyethylene (HXLPE) inserts and conventional polyethylene (PE) inserts of the uncemented Triathlon fixed insert cruciate-retaining total knee arthroplasty (TKA). Secondary objectives included clinical outcomes and patient-reported outcome measures (PROMs).

Aims. Thresholds of acceptable early migration of the components in total knee arthroplasty (TKA) have traditionally ignored the effects of patient and implant factors that may influence migration. The aim of this study was to determine which of these factors are associated with overall longitudinal migration of well-fixed tibial components following TKA. Methods. Radiostereometric analysis (RSA) data over a two-year period were available for 419 successful primary TKAs (267 cemented and 152 uncemented in 257 female and 162 male patients). Longitudinal analysis of data using marginal models was performed to examine the associations of patient factors (age, sex, BMI, smoking status) and implant factors (cemented or uncemented, the size of the implant) with maximum total point motion (MTPM) migration. Analyses were also performed on subgroups based on sex and fixation. Results. In the overall group, only fixation was significantly associated with migration (p < 0.001). For uncemented tibial components in males, smoking was significantly associated with lower migration (p = 0.030) and BMI approached significance (p = 0.061). For females with uncemented components, smoking (p = 0.081) and age (p = 0.063) approached significance and were both associated with increased migration. The small number of self-reported smokers in this study warrants cautious interpretation and further investigation. For cemented components in females, larger sizes of tibial component were significantly associated with increased migration (p = 0.004). No factors were significant for cemented components in males. Conclusion. The migration of uncemented tibial components was more sensitive to patient factors than cemented implants. These differences were not consistent by sex, suggesting that it may be of value to evaluate female and male patients separately following TKA. Cite this article: Bone Joint J 2022;104-B(4):444–451

Aims

Aseptic loosening is a leading cause of uncemented arthroplasty failure, often accompanied by fibrotic tissue at the bone-implant interface. A biological target, neutrophil extracellular traps (NETs), was investigated as a crucial connection between the innate immune system’s response to injury, fibrotic tissue development, and proper bone healing. Prevalence of NETs in peri-implant fibrotic tissue from aseptic loosening patients was assessed. A murine model of osseointegration failure was used to test the hypothesis that inhibition (through Pad4^-/- mice that display defects in peptidyl arginine deiminase 4 (PAD4), an essential protein required for NETs) or resolution (via DNase 1 treatment, an enzyme that degrades the cytotoxic DNA matrix) of NETs can prevent osseointegration failure and formation of peri-implant fibrotic tissue.

Aims

Uncemented mobile bearing designs in medial unicompartmental knee arthroplasty (UKA) have seen an increase over the last decade. However, there are a lack of large-scale studies comparing survivorship of these specific designs to commonly used cemented mobile and fixed bearing designs. The aim of this study was to evaluate the survivorship of these designs.

Aims. Stemmed tibial components are frequently used in revision total knee arthroplasty (TKA). The purpose of this study was to evaluate patient satisfaction, overall pain, and diaphyseal tibial pain in patients who underwent revision TKA with cemented or uncemented stemmed tibial components. Methods. This is a retrospective cohort study involving 110 patients with revision TKA with cemented versus uncemented stemmed tibial components. Patients who underwent revision TKA with stemmed tibial components over a 15-year period at a single institution with at least two-year follow-up were assessed. Pain was evaluated through postal surveys. There were 63 patients with cemented tibial stems and 47 with uncemented stems. Radiographs and Knee Society Scores were used to evaluate for objective findings associated with pain or patient dissatisfaction. Postal surveys were analyzed using Fisher’s exact test and the independent-samples t-test. Logistic regression was used to adjust for age, sex, and preoperative bone loss. Results. No statistically significant differences in stem length, operative side, or indications for revision were found between the two cohorts. Tibial pain at the end of the stem was present in 25.3% (16/63) of cemented stems and 25.5% (12/47) of uncemented stems (p = 1.000); 74.6% (47/63) of cemented patients and 78.7% (37/47) of uncemented patients were satisfied following revision TKA (p = 0.657). Conclusion. There were no differences in patient satisfaction, overall pain, and diaphyseal tibial pain in cemented and uncemented stemmed tibial components in revision TKA. Patient factors, rather than implant selection and surgical technique, likely play a large role in the presence of postoperative pain. Stemmed tibial components have been shown to be a possible source of pain in revision TKA. There is no difference in patient satisfaction or postoperative pain with cemented or uncemented stemmed tibial components in revision TKA. Cite this article: Bone Joint J 2021;103-B(6 Supple A):165–170

Aims

For many designs of total knee arthroplasty (TKA) it remains unclear whether cemented or uncemented fixation provides optimal long-term survival. The main limitation in most studies is a retrospective or non-comparative study design. The same is true for comparative trials looking only at the survival rate as extensive sample sizes are needed to detect true differences in fixation and durability. Studies using radiostereometric analysis (RSA) techniques have shown to be highly predictive in detecting late occurring aseptic loosening at an early stage. To investigate the difference in predicted long-term survival between cemented, uncemented, and hybrid fixation of TKA, we performed a randomized controlled trial using RSA.

Aims

Total knee arthroplasty is an established treatment for knee osteoarthritis with excellent long-term results, but there remains controversy about the role of uncemented prostheses. We present the long-term results of a randomized trial comparing an uncemented tantalum metal tibial component with a conventional cemented component of the same implant design.

Aims

The primary aim of the study was to compare the knee-specific functional outcome of robotic unicompartmental knee arthroplasty (rUKA) with manual total knee arthroplasty (mTKA) for the management of isolated medial compartment osteoarthritis. Secondary aims were to compare length of hospital stay, general health improvement, and satisfaction between rUKA and mTKA.

Aims

Hydroxyapatite coatings for uncemented fixation in total knee arthroplasty can theoretically provide a long-lasting biological interface with the host bone. The objective of this study was to test this hypothesis with propriety hydroxyapatite, peri-apatite, coated tibial components using component migration measured with radiostereometric analysis over two years as an indicator of long-term fixation.

Total knee arthroplasty (TKA) is a cost effective and extremely successful operation. As longevity increases, the demand for primary TKA will continue to rise. The success and survivorship of TKAs are dependent on the demographics of the patient, surgical technique and implant-related factors.

Currently the risk of failure of a TKA requiring revision surgery ten years post-operatively is 5%.

The most common indications for revision include aseptic loosening (29.8%), infection (14.8%), and pain (9.5%). Revision surgery poses considerable clinical burdens on patients and financial burdens on healthcare systems.

We present a current concepts review on the epidemiology of failed TKAs using data from worldwide National Joint Registries.

Cite this article: Bone Joint J 2016;98-B(1 Suppl A):105–12.

A retrospective review was performed of patients undergoing primary cementless total knee replacement (TKR) using porous tantalum performed by a group of surgical trainees. Clinical and radiological follow-up involved 79 females and 26 males encompassing 115 knees. The mean age was 66.9 years (36 to 85). Mean follow-up was 7 years (2 to 11). Tibial and patellar components were porous tantalum monoblock implants, and femoral components were posterior stabilised (PS) in design with cobalt–chromium fibre mesh. Radiological assessments were made for implant positioning, alignment, radiolucencies, lysis, and loosening. There was 95.7% survival of implants. There was no radiological evidence of loosening and no osteolysis found. No revisions were performed for aseptic loosening. Average tibial component alignment was 1.4° of varus (4°of valgus to 9° varus), and 6.2° (3° anterior to 15° posterior) of posterior slope. Mean femoral component alignment was 6.6° (1° to 11°) of valgus. Mean tibiofemoral alignment was 5.6° of valgus (7° varus to 16° valgus). Patellar tilt was a mean of 2.4° lateral (5° medial to 28° lateral). Patient satisfaction with improvement in pain was 91%. Cementless TKR incorporating porous tantalum yielded good clinical and radiological outcomes at a mean of follow-up of seven-years.

Cite this article: Bone Joint J 2014;96-B(11 Suppl A):87–92.

Stress shielding resulting in diminished bone density following total knee replacement (TKR) may increase the risk of migration and loosening of the prosthesis. This retrospective study was designed to quantify the effects of the method of fixation on peri-prosthetic tibial bone density beneath cemented and uncemented tibial components of similar design and with similar long-term survival rates. Standard radiographs taken between two months and 15 years post-operatively were digitised from a matched group of TKRs using cemented (n = 67) and uncemented (n = 67) AGC tibial prostheses. Digital radiograph densitometry was used to quantify changes in bone density over time. Age, length of follow-up, gender, body mass index and alignment each significantly influenced the long-term pattern of peri-prosthetic bone density. Similar long-term changes in density irrespective of the method of fixation correlated well with the high rate of survival of this TKR at 20 years, and suggest that cemented and uncemented fixation are both equally viable.

Cite this article: Bone Joint J 2013;95-B:911–16.

Introduction. Initial stability of the tibial component influences the success of uncemented total knee arthroplasty. In uncemented components, osseointegration provides long-term fixation which is particularly important for the tibial component. Osseointegration is facilitated by minimising bone-implant interface micromotion to within acceptable limits. To investigate initial stability, this study compares the micromotion and initial seating of two uncemented hydroxyapatite-coated tibial components, the Genesis II and Profix. This is the first stability comparison of two hydroxyapatite-coated tibial components. Methods. Six components of each type were implanted into synthetic tibias by a single orthopaedic surgeon. Good coverage was achieved. No screws or articular inserts were used. Initial seating was measured using ImageJ software at five areas on each tibia. Tibias were transected and their proximal section implanted into a molten alloy parallel to horizontal. Dynamic mechanical testing was performed using a hydraulic 858-Bionix machine. Prostheses underwent unilateral axial point-loading of 700N cyclically applied four times. The load was applied to three locations approximating femoral loading points. The loading cycle was repeated six times at each point, allowing micromotion to be recorded at three contralateral locations. Micromotion was measured by optical lasers. After dynamic testing, two tibial components of each type were removed with claw pliers while measuring the force required on the 858-Bionix machine. Implant under-surfaces were photographed for wear. Results. The micromotion readings allowed a directional (subsidence or lift-off) movement profile to be constructed. The absolute micromotion recordings demonstrated areas experiencing the most micromotion. Micromotion was not significantly different between components (P>0.05). Absolute micromotion during posterolateral loading was significantly different (P<0.05). Loading points producing the most absolute micromotion were antero- and centrolateral in Genesis II prostheses and anteromedial and posterolateral in Profix prostheses. The areas which showed the greatest absolute micromotion were anteromedial in Genesis II prostheses and posteromedial and posterolateral in Profix prostheses. Average absolute micromotion did not exceed 75μm. Initial gap ranged from 535–633 μm in Genesis II prostheses and 631–799 μm in Profix prostheses. Initial gap did not significantly correlate with either prosthesis. Pullout force was significantly different (P<0.0001), requiring less than 75N for Profix prostheses and greater than 150N for Genesis II prostheses. Wear was seen anteromedially in all Profix components. In Profix prostheses the only loading point to consistently produce liftoff was anteromedially. Conclusions. Average micromotion is not significantly different in Genesis II and Profix trays during point loading central condylar areas in synthetic tibias. With posterolateral loading the Genesis II was significantly more stable. Unilateral loading demonstrated a pivot type micromotion pattern about the tibial stem in both designs. Seating was not a significant factor influencing micromotion, presumably while the initial gap is small (<800μm). The deficit of an anteromedial peg in the Profix prostheses predisposes to liftoff when this point is loaded. Using a force approximating that of walking, distributed through typical femoral loading points, results in micromotion in both designs at a level not expected to prevent osseointegration

Bone mineral density (BMD) and bone mineral content (BMC) have not been previously assessed in unicompartmental knee replacement (UKR). We studied the early bone changes beneath the uncemented Oxford medial UKR. Our hypothesis was that this implant should decrease the shear stresses across the bone-implant interface and result in improved BMD and BMC beneath the tibial component. Using the Lunar iDXA and knee specific software we developed 7 regions of interest (ROI) in the proximal tibia and assessed 38 patients with an uncemented Oxford UKR at 2 years. We measured the replaced knee and contralateral unreplaced knee using the same ROI and compared the BMD and BMC. The initial precision study in 20 patients demonstrated high precision in all areas. There were 12 males and 16 females with an average age of 65.8 years (46–84 years). ROI 1 and 2 were beneath the tibial tray and had significantly less BMC (p=0.023 and 0.001) and BMD (p=0.012 and 0.002). ROI 3 was the lateral tibial plateau and this area also had significantly less BMC (p=0.007) and BMD (p=0.0001). ROI 4 and 5 immediately below the tibial keel had no significant change. These changes were independent of gender and age. These results were surprising in that the universal loss of BMC and BMD suggested that bone loading of the proximal tibia was not improved even after a UKR. The better BMD and BMC adjacent to the keel confirms other studies that show improved bone in-growth around keels and pegs in the uncemented tibial component. A prospective longitudinal study has been developed to compare BMD and BMC changes over time to see whether these changes are dynamic

Stems improve the mechanical stability of tibial components in total knee replacement (TKR), but come at a cost of stress shielding along their length. Their advantages include resistance to shear, reduced tibial lift-off and increased stability by reducing micromotion. Longer stems may have disadvantages including stress shielding along the length of the stem with associated reduction in bone density and a theoretical risk of subsidence and loosening, peri-prosthetic fracture and end-of-stem pain. These features make long stems unattractive in the primary TKR setting, but often desirable in revision surgery with bone loss and instability. In the revision scenario, stems are beneficial in order to convey structural stability to the construct and protect the reconstruction of bony defects. Cemented and uncemented long stemmed implants have different roles depending on the nature of the bone loss involved.

This review discusses the biomechanics of the design of tibial components and stems to inform the selection of the component and the technique of implantation.

Purpose: To investigate the effect that gender may have on the RSA defined migration pattern of cemented and uncemented tibial components in total knee arthroplasty (TKA). Method: 70 patients with primary osteoarthritis of the knee were randomized to receive a Nexgen uncemented Trabecular Metal (TM) monoblock tibial component (n=37; 20 female; mean age=66 years; mean BMI=32) or cemented cobalt chrome modular tibial cmponent (n=33; 19 female; mean age=65 years; mean BMI=33). The same design of posterior stabilized tibial component was used in all cases. Four experienced knee surgeons followed a standardized surgical technique (PCL resection, patella resurfacing, RSA bead placement in poly-ethylene and tibia) and post-operative protocol (CPM as tolerated, no drains, WBAT). Within 4 days of surgery and at 6, 12 and 24 months post-operatively patients underwent bi-planar x-rays. RSA analysis was performed with MB-RSA (MEDIS, Leiden). Results were reported as maximum total point motion, and 6 degrees of freedom translations and rotations. A repeated measure ANOVA was used to test for differences and all statistical analysis was performed using Minitab V.14 (Minitab Inc, State College, PA, USA). Results: Highly significant differences were seen in the migration patterns in females between the TM and cemented tibial components. Females with the TM implant tended to rotate internally (0.29° vs. −0.16°, p< 0.0001), tilt posteriorly (−0.49° vs. 0.01°, p< 0.0001) and subside (−0.357mm vs. 0.00mm, p< 0.0001) compared with the female subjects with the cemented implant. In the male group, only subsidence was different between the TM and cemented groups (−0.344mm vs. −0.01mm, p< 0.0001). Conclusion: Uncemented TM implants in females tended to tilt posteriorly, rotate internally and subside. Uncemented implants in males tended only to subside. The increased tilting and rotation detected in females could be due to lower BMD or to mismatching between the shape of the female proximal tibial and the tibial component. These results may have implications for the current use of uncemented implants in females and for future design of uncemented implants for the female population

Purpose: To investigate the association between pre-operative gait patterns and the RSA defined migration migration pattern of cemented and uncemented tibial components post total knee arthroplasty (TKA). Method: 43 patients with primary osteoarthritis of the knee underwent Optotrack gait analysis in the week before TKA surgery. Three-dimensional net external knee joint moments and angles were calculated with inverse dynamics. The variability in subject gait patterns was captured with a set of discrete scores that represented weightings on objectively-extracted features of the gait waveform data using principal component analysis. The subjects were randomized to receive the uncemented Nexgen Trabecular metal Monoblock tibial component (n=22; mean age=66 years; mean BMI=32) or the modular cemented cobalt chrome tibial component (n=21; mean age=65 years; mean BMI=33). Both groups were posterior-stabilized and used the same design femoral component. Four experienced surgeons followed a standardized surgical technique and postoperative protocol. Within 4 days of surgery and at 6 months post-operatively, patients had bi-planar knee x-rays taken. RSA analysis was performed with MB-RSA (MEDIS, Leiden). RSA results were reported as maximum total point motion, translations and rotations at 6 months. Spearman’s rank correlations were used to examine the relationship between the first three principle component (PC) scores for each gait variable and the RSA metrics (P< 0.05). Results: There was a highly significant correlation between MTPM and the first principal component (PC) of the knee adduction moment, which represented the overall magnitude of moment during the stance phase of the gait cycle (r=0.459, P=0.005). Higher preoperative knee adduction moment magnitudes were associated with greater MTPM postoperatively. Internal rotation of the components was correlated with the second PC of internal/external rotation moment at the knee, which represented the magnitude of the moment at load acceptance (r=0.341, P=0.042). Greater knee internal rotation moments at load acceptance preoperatively were associated with higher internal rotation postoperatively. Conclusion: The amount of postoperative migration of the tibial component in TKA was found to be correlated with preoperative gait patterns, particularly to the magnitude of the knee adduction moment.. These results suggest that surgical success and prosthesis survivorship may be dependent on the preoperative mechanical environment of the knee joint (i.e., gait)

The purpose of this study was to evaluate a high flex porous tantalum metal monoblock component system implanted through a MIS technique.

A fellowship trained surgeon proficient in MIS surgery performed 109 consecutive TKAs in 95 patients. Patients were implanted with a tantalum monoblock tibia and a fiber-metal cruciate-retaining high flex femur through a MIS midvastus approach. Ninety uncemented porous tantulum monoblock patellae and 19 cemented all polyethylene patellae were implanted.

Knee Society scores and Knee Society radiographic scores were calculated in all patients. Follow-up for a minimum of 2 years was performed in 109 knees. The average follow up was 39 months. Sixty-six percent of the patients were female and 34% male. The average age was 66 years. The average preoperative Knee Society Knee score was 36. The average preop Knee Society Functional Score was 46. Osteoarthritis was the primary diagnosis in 104 knees. Rheumatoid arthritis and Hemophilia was the diagnosis in two knees each.

The average Knee Society Knee Score improved to 89. The average Knee Society Function score improved to 86. 106 of the knees were rated good or excellent and three knees were rated poor. Two patellar revisions were performed for loose components and one for patellar misalignment. One patella fracture occurred that required ORIF. One femoral component was revised for loosening. There were nonprogressive radiographic lucencies demonstrated on 4 tibial components. One tibial component was rated loose. There were radiographic lucencies on 5 femoral components, all nonprogressive. There were two uncemented tantalum patellar components with stable radiolucencies.

Early results in 109 consecutive porous tantalum metal tibial and high flex cruciate-retaining femoral components implanted through an MIS midvastus approach have a high rate of success at a minimum followup of two years.

Introduction Cemented fixation of the tibial component is the standard treatment for patients older than 65 with long-standing excellent results. Whether cemented fixation is best even for younger patients is still debated, and if uncemented fixation is chosen, the question remains as to whether screws are necessary as an adjunct. We present the results of a prospective randomized study comparing cemented and two modes of uncemented fixation. Methods Thirty-five patients (mean age 56 years, range 29 to 64) were operated with the Profix (Smith& Nephew) TKA for gonarthrosis grade III to V. At the operation, the patients were randomly allocated to fixation of the tibial component with cement (Group C, n=6), uncemented fixation with hydroxyapatite (HA) coating without screws (Group HA, n=14), or uncemented fixation with HA coating and with screws (Group HA+, n=15). The implants and tibiae were prepared for RSA with tantalum markers. RSA was performed post-operatively, three, 12 and 24 months post-op. Results There were no complications or revisions during the follow-up. For all three types of fixation the migration was larger during the initial three months, after which the migration leveled off. At three months, subsidence and tilting of the implant was significantly larger for group HA- compared to group C (P = 0.009 − 0.036), with the migration for group HA+ in between. This difference between the groups persisted up to 24 months. When examining the migration from three to 24 months, the implants in all three groups displayed very small migration, magnitudes well below the detection limit of RSA. There were no differences in magnitude of migration between the three groups between three and 24 months. Conclusions The uncemented tibial component displays relatively large migration within the first three months compared to the cemented implant, and uncemented fixation without screws has larger migration than when screws are used. This larger initial migration for the uncemented fixation probably is due to “setting-in” of the prostheses. However, if the uncemented implant “survives” this early period, the results of the present study indicate a good long term prognosis, even when no screws are used for additional stability. This is important, since osteolysis frequently has been observed in relation to screws in the proximal tibia. One reason for the stable fixation of the uncemented implants may be the use of HA-coating. In relation to the conduct of this study, one or more of the authors is in receipt of a research grant from a non-commercial source

Aims: To prospectively study the optimum fixation of the tibial component in patients younger than 65 years, where the mode of fixation is randomized. Methods: 35 patients (mean age 56 years, range 29 to 64) were operated with the Profix (Smith& Nephew) TKA due to gonarthrosis grade III to V. The patients were randomly allocated to fixation of the tibial component with cement (Group C) (n=6), uncemented fixation with hydroxyapatite coating (HA) without screws (Group HA−) (n=14), or uncemented fixation with HA coating and with screws (Group HA+) (n=15). Radiostereometry (RSA) was performed postop., 3, 12 and 24 months postop. Results: There were no complications or revisions during the follow-up. Up to 3 months the cemented implants migrated the least and the HA- group the most (P = 0.009 – 0.036). From 3 to 24 months however, the implants in all three groups displayed very small migration, magnitudes well below the detection limit of RSA, and there were no differences between the three groups. Conclusions: The uncemented tibial component displays relatively large migration within the first 3 months compared to the cemented implant, and uncemented fixation without screws have larger migration than when screws are used. This larger initial migration for the uncemented fixation probably is due to “setting-in” of the prostheses. However, if the uncemented HA-coated implant “survives” this early period, the results of the present study indicate a good long term prognosis, even in designs where no screws are used for additional stability