Aims. The aim of this study was to investigate the association between fracture displacement and survivorship of the native hip joint without conversion to a total hip arthroplasty (THA), and to determine predictors for conversion to THA in patients treated nonoperatively for acetabular fractures. Methods. A multicentre cross-sectional study was performed in 170 patients who were treated nonoperatively for an acetabular fracture in three level 1 trauma centres. Using the post-injury diagnostic CT scan, the maximum gap and step-off values in the weightbearing dome were digitally measured by two trauma surgeons. Native hip survival was reported using Kaplan-Meier curves. Predictors for conversion to THA were determined using Cox regression analysis. Results. Of 170 patients, 22 (13%) subsequently received a THA. Native hip survival in patients with a step-off ≤ 2 mm, > 2 to 4 mm, or > 4 mm differed at five-year follow-up (respectively: 94% vs 70% vs 74%). Native hip survival in patients with a gap ≤ 2 mm, > 2 to 4 mm, or > 4 mm differed at five-year follow-up (respectively: 100% vs 84% vs 78%). Step-off displacement > 2 mm (> 2 to 4 mm hazard ratio (HR) 4.9, > 4 mm HR 5.6) and age > 60 years (HR 2.9) were independent predictors for conversion to THA at follow-up. Conclusion. Patients with minimally displaced acetabular fractures who opt for nonoperative fracture treatment may be informed that fracture displacement (e.g. gap and step-off) up to 2 mm, as measured on CT images, results in limited risk on conversion to THA. Step-off ≥ 2 mm and age > 60 years are predictors for conversion to THA and can be helpful in the shared decision-making process. Cite this article: Bone Joint J 2023;105-B(9):1020–1029

Objectives. Because posterior cruciate ligament (PCL) resection makes flexion gaps wider in total knee replacement (TKR), preserving or sacrificing a PCL affects the gap equivalence; however, there are no criteria for the PCL resection that consider gap situations of each knee. This study aims to investigate gap characteristics of knees and to consider the criteria for PCL resection. Methods. The extension and flexion gaps were measured, first with the PCL preserved and subsequently with the PCL removed (in cases in which posterior substitute components were selected). The PCL preservation or sacrifice was solely determined by the gap measurement results, without considering other functions of the PCL such as ‘roll back.’. Results. Wide variations were observed in the extension and flexion gaps. The flexion gaps were significantly larger than the extension gaps. Cases with 18 mm or more flexion gap and with larger flexion than extension gap were implanted with cruciate retaining component. A posterior substitute component was implanted with the other cases. Conclusions. In order to make adequate gaps, it is important to decide whether to preserve the PCL based on the intra-operative gap measurements made with the PCL intact. Cite this article: Bone Joint Res 2014;3:95–100

[Introduction]. As an essential concept in TKA, preparing equalized rectangular extension and flexion gaps is recognized as desirable to ensure proper knee kinematics. However, in the ways that was recommended by an implant manufacturer, the adjustments are so difficult, and for inexperienced doctor, we don't have an ideal technique for an additional cutting up and ligament balancing. Then, the New method (Precut method) was introduced in order to enable an ideal adjustments. [Method]. Sixty eights patients with osteoarthritis of the knee received TKAs using Precut method. This method is the following. At first, proximal tibia was resected 10 mm by standard cutting device. And then, femoral posterior condyle was resected 4 mm lesser than cutting line by measured resection technique (Precut method). In the next, using the spacer block 1 mm unit and the Precut trial implant (8 mm; distal femur 4 mm; posterior condyle), we investigated the bone gap and the component gap (put the Precut trial on the distal femur). Finally, we calculated the amount of the final cutting value based on the component gap. The survey item measured the bone gap at extension and flexion, the component gap at extension and flexion after putting the Precut trial on. Then we compared the gap difference with and without the Precut trial. [Result]. Our results showed that the extension gap with the Precut trial was smaller than the predicted value with the Precut trial (mean: 8.66 mm/8.18 mm), the flexion gap with the Precut trial was larger than the predicted value with the Precut trial (mean: 13.2 mm/14.1 mm). The extension gap had reduced by 0.48 mm and the flexion gap enlarged by 0.3 mm. [Discussion]. In TKA, it is difficult to make extension gap and flexion gap equal. Therefore, after putting the final implant, we experienced the case s such as could not stretch fully in extension, such as had instability in flexion. However, in this method, we will earn the ideal stability in postoperative condition. It is because that after putting the Precut trial, we measured implant gap at extension and flexion, and then decided the final osteotomy value to eliminate the gap difference. [Conclusion]. As we measured extension gap and flexion gap in condition which put the Precut trial on, before the final osteotomy, we can make an equal gap at extension and flexion. We think a useful procedure for the stability after TKA

Introduction. Although gap balancing technique has been reported to be beneficial for the intra-operative soft tissue balancing in posterior-stabilized (PS)-TKA, excessive release of medial structures for achieving perfect ligament balance would be more likely to result in medial instability, which would deteriorate post-operative clinical results. We have modified conventional gap balancing technique and devised a new surgical concept; named as “medial gap technique” aiming at medial stability with permitting lateral looseness, as physiologically observed in normal knee. Objective. We compared intra-operative soft tissue balance between medial gap technique (MGT) and measured resection technique (MRT) in PS-TKAs. Materials and Methods. The subjects were 210 female patients with varus type osteoarthritic knees, underwent primary PS TKA. The surgical techniques were MGT in 96 patients and MRT in 114 patients. The extension gap was made in the same manners in both groups with medial releases limited until the spacer block could be easily inserted. The residual lateral laxity was permitted. In the MGT group, before posterior femoral osteotomies, varus angles (°) and center gaps (mm) at extension and flexion were measured using an offset type tensor with applying 40 lbs. (177.9N) of joint distraction force. The level and external rotation angle of posterior femoral osteotomies were determined based on the difference of center gaps and varus angles between extension and flexion respectively. Intra-operative joint gap kinematics was measured with femoral trial in place and patello-femoral joint reduced. We measured varus angle and component gap at 8 different knee flexion angles from 0° to 135°. From these component gaps and varus angles, we calculated a medial and lateral compartment gaps (MCG and LCG) by using a trigonometric function. Also we calculated the increase of both compartment gaps from those at full extension, named as joint gap loosening (mm). Both compartment gaps and joint gap loosening were compared between 2 groups using unpaired t-test, and the difference between MCG and LCG in each group were compared using paired t- test (p<0.05). Results. The mean MCGs showed significantly smaller value than LCGs at all flexion angles in both groups (Fig.1). Both medial and lateral joint gap loosening were significantly smaller in MGT group than MRT group from mid-flexion to deep flexion (Fig. 2, 3). Discussion. We have reported the joint distraction force affected varus imbalance due to the stiffness difference between medial and lateral structures. This might be a reason why gap technique was performed less quantitatively and with higher risk of medial instability. In MGT, we allowed persistent lateral looseness and applied the difference in varus angle between extension and flexion to the external rotation angle of femoral component. Results showed no medial looseness were observed in MGT like in MRT. The less joint gap loosening with knee flexion were achieved by MGT because the advantage of conventional gap balancing was also incorporated. We found “medial gap technique” was effective for quantitative soft tissue balancing with more stable joint gap kinematics and no medial looseness

Introduction: Soft tissue balancing remains the most subjective and most artistic of current techniques in total knee arthroplasty. The flexion gap is traditionally measured at approximately 45 degree of hip flexion and 90 degree of knee flexion on the operation table. Despite of aiming equal joint gaps or tensions in flexion and extension, influence of the thigh weight on the flexion gap has not been documented. Therefore, the purpose of this study was to examine the flexion gaps in the 90-90 degree flexed position and the traditional 45-90 degree flexed position of hip-knee joints. Materials and methods: Thirty patients with osteoarthritic knee underwent total knee arthroplasty. After the PCL sacrifice, soft tissue releases, and bone cuts, the specially designed tenser which has two load cells was employed. 160N was applied to open the joint gaps in the traditional 45-90 degree flexed position and the 90-90 degree flexed position of hip-knee joints. Results: The flexion gap in the 90-90 degree flexed position of hip-knee joints was 2.1±1.2mm wider than that in the traditional 45-90 degree flexed position of hip-knee joints. The flexion gap had significant difference between the two different hip flexion angles (p< 0.001). Discussions: In the traditional 45-90 degree flexed position of hip-knee joints on the operation table, the flexion gap is approximately 45 degree to the gravitation and influenced by the thigh weight. To avoid the influence of the thigh weight and obtain equal joint gaps or tensions in flexion and extension, the flexion gap should be checked in the 90-90 degree flexed position of hip-knee joints

Introduction. Appropriate osteotomy alignment and soft tissue balance are essential for the success of total knee arthroplasty (TKA). The management of soft tissue balance still remains difficult and it is left much to the surgeon's subjective feel and experience. We developed an offset type tensor system for TKA. This device enables objective soft tissue balance measurement with more physiological joint conditions with femoral trial component in place and patello-femoral (PF) joint reduced. We have reported femoral component placement decreased extension gap. The purpose of the present study was to analyze the influence of femoral component size selection on the decrease of extension gap in posterior-stabilized (PS) TKA. Material & Method. 120 varus type osteoarthritic knees implanted with PS TKAs (NexGen LPS flex: Zimmer) were subjected to this study. All TKAs were performed using measured resection technique with anterior reference. The femoral component size was evaluated intra-operatively using conventional femoral sizing jig. The selected femoral component size was expressed by the antero-posterior (AP) size increase (mm) comparing to that of original femoral condyles. Gap measurements were performed using a newly developed offset type tensor device applying 40lbs (178N) of joint distraction force. Firstly, conventional osteotomy gaps (mm) were measured at extension and flexion. Secondary, component gaps (mm) after femoral trial placement with PF joint reduced were evaluated at 0° and 90° of knee flexion. To compare conventional osteotomy gaps and component gaps, estimated extension and flexion gaps were calculated by subtracting the femoral component thickness at extension (9mm) and flexion (11mm) from conventional osteotomy gaps respectively. The decrease of gap at extension and flexion were calculated with estimated gaps subtracted by component gaps. The simple linear regression analysis was used to evaluate the influence of selected femoral component size on the decrease of gap after femoral component placement. Results. The mean extension and flexion conventional osteotomy gaps were 25.7 and 28.2 mm, and estimated gaps were 16.7, 17.2 mm respectively. The component gaps were 11.1, 16.9 mm at 0° and 90° of knee flexion respectively. Extension joint gap was significantly decreased as much as 5.6mm after femoral component placement, but flexion gap showed no significant differences. Selected femoral component size showed a positive correlation to the decrease of gap after femoral component placement (Fig 1). Discussion & Conclusion. This result indicates that AP femoral component size variation affects not only flexion gap but also extension gap in PS TKA. With the larger femoral component size selected, the more protrusion of posterior condyles would increase the more tension on the posterior structures and resulted in the more decrease of joint gap after femoral component placement at full extension. This mechanism might play a physiological role on the prevention of knee hyper-extension, and would be affected by flexion contracture. Accordingly, we conclude that the surgeon should aware of the effect of femoral component placement on the gap control, and femoral component size selection affects not only flexion gap but also extension gap after femoral component placement in PS TKA

Introduction. Patient specific surgical guide (PSSG) is a relatively new technique for accurate total knee arthroplasty (TKA), and there are many reports supporting PSSG can reduce the rate of outlier in the coronal plane. We began to use PSSG provided by Biomet (Signature®) and have reported the same results. Before using Signature, we performed TKA by modified gap technique (parallel cut technique) to get the well balanced flexion gap. Signature is the one of the measured resection technique using the anatomical landmarks as reference points on the images of CT or MR taken before surgery. We usually measure the center gap width and gap balance during operation with the special device “knee balancer”(Fig. 1) that can be used on patella reposition. After cutting all of the bone with Signature, gap balance in the extension position was very good but the gap balance was shown slight lateral opening in the 90 degrees flexion position. So we have changed the surgical procedure. We use Signature for cutting only distal femur and proximal tibia to get extension gap and apply the modified gap technique to decide the rotation of the femoral component (Signature with modified gap technique). The purpose of this study is to compare the gap balance between the two techniques. Materials & Methods. From November, 2012 through March, 2014, 50 CR type TKA (Vanguard Knee®, Biomet) in osteoarthritis patients were performed using Signature. 25 TKA were performed using only Signature (group S) and other 25 TKA were done using Signature with modified gap technique (group SG). After all osteotomies of femur and tibia were completed, applying femoral trial, center gap width and gap balance (plus means lateral opening angle) were measured using knee balancer with respect to 30 degrees of the knee flexion angle from zero to 120 degrees (Fig. 2). Results. From knee flexion angle 0 to 120 degrees, gap width was 10.8, 11.9, 11.3, 11, 2 10.8mm in group S, 11.9, 12.6, 11.9, 12.0, 11.8mm in group SG, the range of the gap width was small, 1.1mm and 0.8mm. Gap balance was 0.4, 0.6, 1.0, 2.6, 3.6 degrees in group S and 0.1, 0.1, 0.5, 0.6, 2.6 degrees in group SG. Discussion. With both techniques, Signature and Signature with gap technique, center gap width stayed constant. When it comes to gap balance, in Signature with gap technique group, gap balance were good and constant in knee flexion angle from zero to 90 degrees. But in Signature group, the more flexion angle increased, the more lateral opening angle enlarged. So Signature with gap technique is better than only Signature to get good gap balances during knee movement

Balancing the PCL in a PCL-retaining total knee replacement (TKR) is important, but sometimes difficult to execute in an optimal manner. Due to the orientation of the PCL it is conceivable that flexion gap distraction will lead to anterior movement of the tibia relative to the femur. This tibio-femoral repositioning influences the tibio-femoral contact point, which on its turn affects the kinematics of the TKR. So far, the amount of tibiofemoral repositioning during flexion gap distraction is unknown which leads to uncertain kinematic effects after surgery. The goal of this study was to quantitatively describe the parameters of the flexion gap (gap height, anterior tibial translation and femoral rotation) and their relationship while the knee is distracted during implantation of a PCL-retaining TKR with the use of computer navigation. Furthermore, the effect of PCL elevation angle on the flexion gap parameters was determined. In 50 knees, during a ligament-guided TKR procedure, the flexion gap was distracted with a double-spring tensor with 100 and 200 N after the tibia had been cut. The flexion gap height, anterior tibial translation and femoral rotation were measured intra-operatively using a CT-free navigation system. PCL elevation was calculated based on the femoral and tibial insertion sites as indicated by the surgeon with the pointer of the navigation system. To identify a relationship between flexion gap height increase and anterior tibial translation, the ratio between anterior translation and gap height increase was determined for each patient between 100 and 200 N. The mean gap height increased 2.2 mm (SD 0.96) and mean increase in anterior tibial translation was 4.2 mm (SD 1.6). Hence, on average, for each mm increase in gap height, the tibia moved 1.9 mm (SD 0.96) in anterior direction. Knees with a steep PCL showed significantly more AP translation for each mm gap height increase (gap/AP-ratio was 1 : 2.31 (SD 0.63)) compared to knees with a flat PCL (gap/AP-ratio was 1 : 1.73 (SD 0.50)). The increase in femur (exo)rotation was on average 0.60° (SD 1.4). With a tensioned PCL the tibia will move anteriorly on average 1.9 mm for every extra mm that the flexion gap is increased. The flexion gap dynamics can be explained in part by the orientation of the PCL: the greater the elevation angle, the more anterior tibial displacement during distraction of the flexion gap. The surgeon must be aware that distraction of the flexion gap influences the tibiofemoral contact point. The tibio-femoral contact point will move posteriorly and stresses in the PCL will rise and produce limited flexion and pain. In case of a conforming insert AP-movement will be limited but high PE stresses may be introduced that can lead to wear. This information may be helpful in selecting the optimal soft tissue balancing procedure and the optimal PE insert thickness in PCL retaining TKR

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. Methods. A prospective cohort study of 165 patients undergoing functionally-aligned TKA was performed (176 TKAs). With trial components in situ, medial and lateral extension and flexion gaps were measured using robotic navigation while applying valgus and varus forces. The ICLD between medial and lateral compartments was measured in extension and flexion with the load sensor. The null hypothesis was that stressed gap symmetry would not correlate directly with sensor-defined soft tissue balance. Results. In TKAs with a stressed medial-lateral gap difference of ≤1 mm, 147 (89%) had an ICLD of ≤15 lb in extension, and 112 (84%) had an ICLD of ≤ 15 lb in flexion; 157 (95%) had an ICLD ≤ 30 lb in extension, and 126 (94%) had an ICLD ≤ 30 lb in flexion; and 165 (100%) had an ICLD ≤ 60 lb in extension, and 133 (99%) had an ICLD ≤ 60 lb in flexion. With a 0 mm difference between the medial and lateral stressed gaps, 103 (91%) of TKA had an ICLD ≤ 15 lb in extension, decreasing to 155 (88%) when the difference between the medial and lateral stressed extension gaps increased to ± 3 mm. In flexion, 47 (77%) had an ICLD ≤ 15 lb with a medial-lateral gap difference of 0 mm, increasing to 147 (84%) at ± 3 mm. Conclusion. This study found a strong relationship between intercompartmental loads and gap symmetry in extension and flexion measured with prostheses in situ. The results suggest that ICLD and medial-lateral gap difference provide similar assessment of soft-tissue balance in robotic arm-assisted TKA. Cite this article: Bone Jt Open 2021;2(11):974–980

Introduction. Infected big gap non-union of femur and tibia are difficult to treatment because of infection, bone loss, shortening, poor sift tissue over and deformity. Step by step management and definitive treatment by Ilizarov fixator was achieved in our cases. Materials and Methods. A long defect which is more than 10cm in femur and tibia because of infection and gap, tumor resection, traumatic loss, which is very difficult to treat by conventional method and that's why we treated that type defect by Tibialization of fibula with Ilizarov technique. Management of infected big gap non-union of the femur include debridement and bone transport by Ilizarov technique by using Ilizarov fixator we can correct deformities, regenerate new bone without bone grafting, correct LLD and patient can weight bear during the course of treatment. We retrospectively reviewed records of 246 consecutive patients who underwent distraction osteogenesis using Ilizarov compression-distraction device for infected big gap INU of femur and tibia from 2000 to 2020. Results. All healed with the application of Ilizarov fixator, 5 needed reapplications of Ilizarov to achieve 100% union. 210 were excellent, 25 good and 6 were fair by ASAMI criteria. Mean Ilizarov duration was 366 days (130–250). Mean 8.2 cm length was achieved in the regenerate. Conclusions. A well plan step by step Ilizarov technique to cover infected gap non-union of femur and tibia is an excellent method in challenging cases. Excellent results cannot be achieved with conventional methods but can be easily achieved with Ilizarov technique within 1–2 years

INTRODUCTION. Mechanical alignment in TKA introduces significant anatomic modifications for many individuals, which may result in unequal medial-lateral or flexion-extension bone resections. The objective of this study was to calculate bone resection thicknesses and resulting gap sizes, simulating a measured resection mechanical alignment technique for TKA. METHODS. Measured resection mechanical alignment bone resections were simulated on 1000 consecutive lower limb CT-Scans from patients undergoing TKA. Bone resections were simulated to reproduce the following measured resection mechanical alignment surgical technique. The distal femoral and proximal tibial cuts were perpendicular to the mechanical axis, setting the resection depth at 8mm from the most distal femoral condyle and from the most proximal tibial plateau (Figure 1). If the resection of the contralateral side was <0mm, the resection level was increased such that the minimum resection was 0mm. An 8mm resection thickness was based on an implant size of 10mm (bone +2mm of cartilage). Femoral rotation was aligned with either the trans-epicondylar axis or with 3 degrees of external rotation to the posterior condyles. After simulation of the bone cuts, media-lateral gap difference and flexion-extension gaps difference were calculated. The gap sizes were calculated as the sum of the femoral and tibial bone resections, with a target bone resection of 16mm (+ cartilage corresponding to the implant thickness). RESULTS. For both the varus and valgus knees, the created gaps in the medial and lateral compartments were reduced in the vast majority of cases (<16mm). The insufficient lateral condyle resection distalises the lateral joint surface by a mean of 2.1mm for the varus and 4.4mm for the valgus knees. The insufficient medial tibial plateau resection proximalises the medial joint surface by 3.3mm for the varus and 1.2mm for the valgus knees. Medio-lateral gap imbalances in the extension space of more than 2mm) occurred in 25% of varus and 54% of valgus knees and significant imbalances of more than 5mm were present in up to 8% of varus and 19% of valgus knees. Higher medio-lateral gap imbalances in the flexion space were created with trans epicondylar axis versus 3 degrees to the posterior condyles (p<0.001). Using trans epicondylar axis, only 49% of varus and 18% of valgus knees had less than 3mm of imbalance in both media-lateral and flexion-extension gaps together. DISCUSSION AND CONCLUSION. A systematic use of the tested measured resection mechanical alignment technique for TKA leads to many cases with medio-lateral or flexion-extension gap asymmetries. Some medio-lateral imbalances may not be correctable surgically and may results in TKA instability. Other versions of the mechanical alignment technique or other alignment methods that better reproduce knee anatomies should be explored. For any figures or tables, please contact the authors directly

Background. There are few reports including natural course of initial gap in total hip arthroplasty. The purpose of this study is to investigate the incidence of initial gap in the PSL type shells and its natural course. Methods. Total of 386 THAs with Trident or TriAD PSL shells were performed between January 2000 and December 2014. Exclusion criteria were shells with screw fixations (n=189), previous pelvic osteotomy (n=15) and less than 3 years’ follow-up (n=11). Finally, our study included 171 hips. Average age was 56.8 (17∼83) years at THA and average follow-up time was 8.3 (3∼16.3) years; 112 (66%) were women; and 120 hips (70.2%) had osteoarthrosis. As radiographic evaluation, we checked presence or absence of initial gap, maximum size of it, gap filling and cup stability. The presence of initial gap was defined as gap present on post-operative anteroposterior X-ray measuring 1mm or greater. Gap filling was defined as confirmed trabecular formation between the cup and acetabular floor without cup migration. And we determined the time to gap filling. As clinical evaluation, we retrospectively checked Harris Hip Score (HHS) at pre-operative and final follow-up period, and presence of shell revision. Furthermore, we compared clinical results with or without initial gap. Results. Initial gap was confirmed at 85 hips (49.7%) and mean maximum size was 2.1 (1∼6.3) mm. Mean gap filling occurred at 2.5 (± 1.4) years and there was no unstable cup. Comparing clinical results with or without initial gap, pre-operative HHS was not significantly associated with initial gap (57.8 and 56.3, respectively, p=0.41). HHS at final follow-up period was also not significantly associated with initial gap (88.4 and 87.5, respectively, p=0.49). There was no shell revision with or without initial gap. Discussion. Initial gap of hemispherical type shell is reported that its incidence is 16∼38% and initial gap is not associated with clinical outcome. Our results show that PSL type shell occurs initial gap more frequently than hemispherical type shells. Conclusion. Initial gap of PSL type shell was confirmed at 85 hips (49.7%) and mean gap filling occurred at 2.5 years. Initial gap did not affect shell revision and clinical outcome

Within an ageing population, the morbidity and mortality burden of neck of femur fractures will only worsen. Financially incentivising acute Trusts via the Best Practice Tariff for inpatient care has yielded good results(1,2,3,4) but post-discharge care is still variable. Most importantly, restoring patients to their pre-fracture mobility is key to their quality of life(5,6) and reducing both readmissions to hospital(7,8) and expensive local authority residential care. Unfortunately, physiotherapist vacancies are in their thousands(9,10) leading to waiting times of around three months once discharged(11). In 2019, the Royal Derby Hospital created a novel Hip Fracture Patient Advocate (HFPA) to observe those who have fallen through gaps in community services. It involves monitoring patients’ progression, signposting to appropriate services, flagging issues to the responsible consultant and assisting in physical mobilisation. A retrospective review examined data from patients discharged to their own homes. This included demographics, residential status and mobility, both pre-fracture and at 120 days post-fracture. Mobility was classified into five categories, in line with the national hip fracture database. In 2018, of 238 patients, 41.2% returned to their baseline or increased mobility, and, after the introduction of the HFPA in 2019, this figure increased to 48.2%. In one year, there was a 7% increase in patients recovering their baseline mobility. This is a cost-effective intervention that can successfully improve mobility, leading to improved long-term outcomes. This includes the potential to reduce acute readmissions and the need for residential care, appealing to Integrated Care Boards. It also bridges the gap to primary care to optimise medical management and after further development, could be financially-incentivised via the Best Practice Tariff. Rather than thinking more expensive clinicians are required, this study proposes that a HFPA can garner better outcomes for both the patient and the wider system

Introduction and Objective. Management of gap non-union of the tibia, the major weight bearing bone of the leg remains controversial. The different internal fixation techniques are often weighed down by relatively high complication rates that include fractures which fail to heal (non-union). Minimally invasive techniques with ring fixators and bone transport (distraction osteogenesis) have come into picture as an alternative allowing alignment and stabilization, avoiding a graduated approach. This study was focused on fractures that result in a gap non-union of > 6 cm. Ilizarov technique was employed for management of such non-unions in this case series. The Ilizarov apparatus consists of rings, rods and kirschner wires that encloses the limb as a cylinder and uses kirschner wires to create tension allowing early weight bearing and stimulating bone growth. Ilizarov technique works on the principle of distraction osteogenesis, that is, pulling apart of bone to stimulate new bone growth. Usually, 4–5 rings are used in the setup depending on fracture site and pattern for stable fixation. In this study, we demonstrate effective bone transport and formation of gap non-union more than 6 cm in 10 patients using only 3 rings construct Ilizarov apparatus. Materials and Methods. This case study was conducted at Dr. D. Y. Patil Medical Hospital, Navi Mumbai, Maharashtra, India. The study involved 10 patients with a non-union or gap > 6 cm after tibial fracture. 3 rings were used in the setup for the treatment of all the patients. Wires were passed percutaneously through the bone using a drill and the projecting ends of the wires were attached to the metal rings and tensioned to increase stability. The outcome of the study was measured using the Oxford Knee scoring system, Functional Mobility Scale, the American Foot and Ankle Score and Visual Analog Scale. Further, follow up of patients was done upto 2 years. Results. All the patients demonstrated good fixation as was assessed clinically and radiologically. 9 patients had a clinical score of > 65 which implied fair to excellent clinical rating. The patients showed good range of motion and were highly satisfied with the treatment as measured by different scoring parameters. Conclusions. In this case study, we demonstrate that the Ilizarov technique using 3 rings is equally effective in treating non-unions > 6 cm as when using 4–5 rings. Obtaining good clinical outcome and low complication rate in all 10 patients shows that this modified technique can be employed for patients with such difficulties in the future

Background. Adjusting the joint gap length to be equal in both extension and flexion is an important issue in total knee arthroplasty (TKA). Tight flexion gaps occur sometimes, particularly with the cruciate-retaining (CR) type of TKA, and it impede knee flexion. In posterior stabilizing (PS) TKA, because sacrificing the PCL increases the flexion gap, the issue of gap balancing with PS-TKA is usually focused on decreasing the enlarged flexion gap to be equal to the extension gap. It is generally known that posterior tibial slope would affect the flexion gap, however, the extent to which changes in the tibial slope angle directly affect the flexion gap remains unclear. This study aimed to clarify the influence of tibial slope changes on the flexion gap in CR- or PS-TKA. Methods. The flexion gap was measured using a tensor device with the femoral trail component in 20 cases each of CR- and PS-TKA. A wedge plate with a 5° inclination was placed on the tibial cut surface by switching its front–back direction to increase or decrease the tibial slope by 5°. The flexion gap in changing the tibial slope was compared to that of the neutral slope measured with a flat plate that had the same thickness of the wedge plate center. Results. When the tibial slope decreased or increased by 5°, the flexion gap decreased or increased by 1.9 ± 0.6 mm or 1.8 ± 0.4 mm, respectively, with CR-TKA and 1.2 ± 0.4 mm or 1.1 ± 0.3 mm, respectively, with PS-TKA. Conclusions. The influence of changing the tibial slope by 5° on the flexion gap was approximately 2 mm with CR-TKA and 1 mm with PS-TKA. Clinical relevance. This information is useful to consider the effect of manipulating the tibial slope on the flexion gap when performing CR- or PS-TKA

INTRODUCTION. The results of modified gap balancing and measured resection technique have been still controversial. We compared PS-type TKAs for osteoarthritis performed using the modified gap technique and the measured resection to determine if either technique provides superior clinical results. METHODS. The modified gap technique was used in 85 knees, and the measured technique using preoperative CT was used in 70 knees. To compare intra-operative soft tissue balance, bone gap and component gap were measured using original two paddle tensor (20,30,40lb) at 0 degree extension and 90 degrees flexion. To assess the post-operative patella congruency and soft tissue balance, we measured patella tilt, condylar twist angle (CTA) and condylar lift-off angle (LOA) in radiographs. Finally, we evaluated postoperative clinical result (1–5 years) KOOS. Statistical analysis was used by StatView. RESULTS. (1). Component gaps in flexion at measured techniques were bigger than at gap techniques. Lateral flexion-extension gap and lateral-medial balance at 30lb or 40lb in the measured technique were statistically bigger than the gap technique. (2). There were no statistical correlations with patella tilt, CTA and LOA in both techniques. There were no significant differences between each of the two techniques. (3). KOOS of ‘pain during going up or down stairs’ for the measured technique were statistically worse than for the gap technique. DISCUSSION. Intra-operative lateral gap and flexion balance using measured technique were bigger than gap technique, but there were no statistical differences in post-operative LOA and PF congruency in radiographs. Post-operative pain on stairs might be affected by the differences in intra-operative gap and balance between the two techniques with the balanced ligament technique showing more positive results

Inverse Kinematic Alignment (iKA) and Gap Balancing (GB) aim to achieve a balanced TKA via component alignment. However, iKA aims to recreate the native joint line versus resecting the tibia perpendicular to the mechanical axis. This study aims to compare how two alignment methods impact 1) gap balance and laxity throughout flexion and 2) the coronal plane alignment of the knee (CPAK). Two surgeons performed 75 robotic assisted iKA TKA's using a cruciate retaining implant. An anatomic tibial resection restored the native joint line. A digital joint tensioner measured laxity throughout flexion prior to femoral resection. Femoral component position was adjusted using predictive planning to optimize balance. After femoral resection, final joint laxity was collected. Planned GB (pGB) was simulated for all cases posthoc using a neutral tibial resection and adjusting femoral position to optimize balance. Differences in ML balance, laxity, and CPAK were compared between planned iKA (piKA) and pGB. ML balance and laxity were also compared between piKA and final (fiKA). piKA and pGB had similar ML balance and laxity, with mean differences <0.4mm. piKA more closely replicated native MPTA (Native=86.9±2.8°, piKA=87.8±1.8°, pGB=90±0°) and native LDFA (Native=87.5±2.7°, piKA=88.9±3°, pGB=90.8±3.5°). piKA planned for a more native CPAK distribution, with the most common types being II (22.7%), I (20%), III (18.7%), IV (18.7%) and V (18.7%). Most pGB knees were type V (28.4%), VII (37.8%), and III (16.2). fiKA and piKA had similar ML balance and laxity, however fiKA was more variable in midflexion and flexion (p<0.01). Although ML balance and laxity were similar between piKA and pGB, piKA better restored native joint line and CPAK type. The bulk of pGB knees were moved into types V, VII, and III due to the neutral tibial cut. Surgeons should be cognizant of how these differing alignment strategies affect knee phenotype

INTRODUCTION. The extension and flexion gaps are affected by different factors in total knee arthroplasty (TKA). Flexion but not extension gap measurements are influenced by posterior cruciate ligament (PCL) preservation or resection and patella reduction or eversion and thigh weight. If the flexion gap is measured with the thigh placed on the tibia, the measurement results must include the thigh weight; nevertheless, there is no detailed report regarding the thigh weight influence on the flexion gap. In this study, we investigated how thigh weight affected flexion gap measurement. METHODS. Four knees of whole-body fresh-frozen cadavers (Mongolian race) were investigated. The femur and tibia were dissected with a standard measured resection technique. After the femoral component was set, the flexion gap was measured with a knee balancer. The distraction force of 20, 30, and 40 pounds were loaded at the joint level. For each measurement, the influences of the patella reduced or everted (PR or PE) and the PCL preserved or resected (CR or PS) were estimated. The flexion gap was measured five times in four different categories (CR/PR, CR/PE, PS/PR, PS/PE) and the thigh weight was reduced by weights (0, 0.5, 1.0, 2.0, 3.0 kg) using a string and pulley system. During measurement, the femur was just placed on the tibia, and the knee flexion angle was maintained at 90 degrees with a goniometer. After all measurements, the lower limbs were resected, and the thighs were weighed with a scale. Steel-Dwasstest (non-parametric multiple comparison test) were performed for statistical analysis, and p < 0.05 was considered significant. RESULTS. Flexion gap measurement results show over 10 mm difference between the maximum gap (PS/PE, 40 lbs, 3 kg weight reduction) and the minimum gap (CR/PR, 20 lbs distraction, no weight reduction) in this study. When a 0.5 kg weight reduction was applied, there were no significant flexion gap increases compared to no weight reduction situation in almost all categories except for “CR/PR and 40 lbs distraction”. According to the increase of the weight reduction, the flexion gap became larger in all categories. When a 3 kg weight reduction was applied, there were significant flexion gap increases compared to no weight reduction situation in all categories (Table 1-3). The mean thigh weight was 2.3 kg (2.0–2.6 kg). DISCUSSION. The flexion gap is usually measured with the thigh placed on the tibia in TKA, and the measurement results are considered to include the influence of the thigh weight even though this has not been discussed in the literature. From our results, the influence of the thigh weight reduction on the flexion gap was different according to heaviness of the reduction weight. When the reduction weight was over the thigh weight, flexion gap increase relative to the flexion gap without weight reduction was significant in all categories nevertheless different situations of the PCL, patella position, and joint distraction forces. To estimate adequate flexion gap and avoid post-operative flexion gap looseness, the thigh weight should be reduced when the flexion gap is measured

Mechanical alignment (MA) techniques for total knee arthroplasty (TKA) may introduce significant anatomic modifications, as it is known that few patients have neutral femoral, tibial or overall lower limb mechanical axes. A total of 1000 knee CT-Scans were analyzed from a database of patients undergoing TKA. MA tibial and femoral bone resections were simulated. Femoral rotation was aligned with either the trans-epicondylar axis (TEA) or with 3° of external rotation to the posterior condyles (PC). Medial-lateral (DML) and flexion-extension (DFE) gap differences were calculated. Extension space ML imbalances (3mm) occurred in 25% of varus and 54% of valgus knees and significant imbalances (5mm) were present in up to 8% of varus and 19% of valgus knees. For the flexion space DML, higher imbalance rates were created by the TEA technique (p < 0 .001). In valgus knees, TEA resulted in a DML in flexion of 5 mm in 42%, compared to 7% for PC. In varus knees both techniques performed better. When all the differences between DML and DFE are considered together, using TEA there were 18% of valgus knees and 49% of varus knees with < 3 mm imbalances throughout, and using PC 32% of valgus knees and 64% of varus knees. Significant anatomic modifications with related ML or FE gap imbalances are created using MA for TKA. Using MA techniques, PC creates less imbalances than TEA. Some of these imbalances may not be correctable by the surgeon and may explain post-operative TKA instability. Current imaging technology could predict preoperatively these intrinsic imitations of MA. Other alignment techniques that better reproduce knee anatomies should be explored

In unicompartmental knee arthroplasty (UKA), extension gap commonly decreases after inserting the trial components. As most of UKA technique incorporates the fixture of implants using bone cement, it is likely that the gap decreases further when inserting the actual implants. We performed a new additional procedure that enables a precise adjustment of the extension gap. Thirty-two patients who had undergone UKA (ZIMMER Unicompartmental High-Flex Knee System, Zimmer®, Warsaw) using the spacer block technique at our hospital in 2013 were reviewed. Ten cases had difficulties in achieving full extension after the trial implants were inserted, and hence, a new procedure of longitudinal incision between the medial collateral ligament and the posterior capsule was performed. This additional method created a mean increase of 3mm of the extension gap, and facilitated the knee to extend completely. There were no cases that had an increase in the flexion gap. Previously, a tibial osteotomy was added in such cases, but this had a risk of increasing not just the extension gap but also the flexion gap. This method is a valid technique for precise adjustments, and could also be applied to patients with severe flexion contracture to treat by UKA