Aims. Endoprosthetic reconstruction following distal femur tumour resection has been widely advocated. In this paper, we present the design of an uncemented endoprosthesis system featuring a short, curved stem, with the goal of enhancing long-term survivorship and functional outcomes. Methods. This study involved patients who underwent implantation of an uncemented distal femoral endoprosthesis with a short and curved stem between 2014 and 2019. Functional outcomes were assessed using the 1993 version of the Musculoskeletal Tumour Society (MSTS-93) score. Additionally, we quantified five types of complications and assessed osseointegration radiologically. The survivorship of the endoprosthesis was evaluated according to two endpoints. A total of 134 patients with a median age of 26 years (IQR 16 to 41) were included in our study. The median follow-up time was 61 months (IQR 56 to 76), and the median functional MSTS-93 was 83% (IQR 73 to 91) postoperatively. Results. Overall, 21 patients (16%) encountered complications, and the rate of aseptic loosening was 7% (9/134). The survival rate up to 8.5 years was 93% for aseptic loosening as the endpoint, and 88% for any reason as the endpoint, retrospectively. Conclusion. The use of an uncemented distal femoral endoprosthesis with a short, curved stem demonstrated a low incidence of aseptic loosening and achieved long-term survivorship of up to nine years. Meanwhile, aseptic loosening typically occurs in the early stage postoperatively. Cite this article: Bone Joint J 2024;106-B(9):1000–1007

Following resection of tumours in the distal femur, reconstruction with joint-sparing prostheses have shown good short-term functional outcomes. There is however limited literature on the affect of knee-sparing prostheses on function of the distal femoral physis in children of bone growing age. We discuss two patients, a male (11yrs) and female (10yrs) who had joint-sparing distal femoral prostheses inserted for treatment of Ewing’s sarcoma. The knee joint, along with the distal growth plate, was preserved and fixed to the distal end of the prosthesis using uni-cortical screws positioned distal to the physis. In the female, these screws were removed 6 months postop due to prominence of the screws under the skin. In both patients, we assessed radiographs from immediately post[surgery and the most recent follow-up (20 and 28 months respectively). In each set, for the operated limb, we measured the height and width of the distal femoral epiphysis, the total length of the femur and the length of the proximal femoral bone segment from the femoral head to the proximal bone-prosthesis interface. In addition, postoperative assessments of leg lengths, bilaterally, were documented. In both patients, distal femoral epiphyseal height and width in the operated leg showed no significant change following endoprosthetic replacement. In the female, growth did not resume even after removal of the epiphyseal screws. In both patients, lengths of the femur and the proximal bone segment increased significantly following surgery. The patients demonstrated no clinical leg length discrepancy at the most recent follow-up. This study suggests that the function of the distal femoral growth plate ceases following insertion of joint-sparing distal femoral endoprostheses, probably due to trans-physeal fixation. This does not appear to resume following early removal of distal screws. The proximal growth plate, however, continues to function adequately enough to maintain symmetry in overall leg length

Debate surrounds the optimum operative treatment of periprosthetic distal femoral fractures (PDFFs) at the level of well fixed femoral components; lateral locking plate fixation (LLP-ORIF) or distal femoral replacement (DFR). To determine which attributed the least peri-operative morbidity and mortality we performed a retrospective cohort study of 60 consecutive unilateral PDFFs of Su types II (40/60) and III (20/60) in patients ≥60 years; 33 underwent LLP-ORIF and 27 underwent DFR. The primary outcome measure was reoperation. Secondary outcomes included perioperative complications and functional mobility status. Kaplan Meier survival analysis was performed. Cox multivariable regression analysis identified risk factors for reoperation after LLP-ORIF.

Mean length of follow-up was 3.8 years (range 1.0–10.4). One-year mortality was 13% (8/60). Reoperation rate was significantly higher following LLP-ORIF: 7/33 vs 0/27, p=0.008. For the endpoint reoperation, five-year survival was better following DFR: 100% compared to 70.8% (51.8 to 89.8 95%CI) (p=0.006). For the endpoint mechanical failure (including radiographic loosening) there was no difference at 5 years: ORIF 74.5% (56.3 to 92.7); DFR 78.2% (52.3 to 100), p=0.182). Reoperation following LLP-ORIF was independently associated with medial comminution: HR 10.7 (1.45 to 79.5, p=0.020). Anatomic reduction was protective against reoperation: HR 0.11(0.013 to 0.96, p=0.046). When inadequately fixed fractures were excluded differences in survival were no longer significant: reoperation (p=0.156); mechanical failure (p=0.453).

Reoperation rates are higher following LLP-ORIF of low PDFFs compared to DFR. Where adequate reduction, proximal fixation and augmentation of medial comminution is used there is no difference in survival between LLP-ORIF and DFR.

Introduction. Surgeons commonly resect additional distal femur during primary total knee arthroplasty (TKA) to correct a flexion contracture to restore range of motion and knee function. However, the effect of joint line elevation on the resulting TKA kinematics including frontal plane laxity is unclear. Thus, our goal was to quantify the effect of additional distal femoral resection on passive extension and mid-flexion laxity. Methods. Six computational knee models with capsular and collateral ligament properties specific to TKA were developed and implanted with a contemporary posterior-stabilized TKA. A 10° flexion contracture was modeled by imposing capsular contracture as determined by simulating a common clinical exam of knee extension and accounting for the length and weight of each limb segment from which the models were derived (Figure 1). Distal femoral resections of 2 mm and 4 mm were simulated for each model. The knees were then extended by applying the measured knee moments to quantify the amount of knee extension. The output data were compared with a previous cadaveric study using a two-sample two-tailed t-test (p<0.05) [1]. Subsequently, varus and valgus torques of ±10 Nm were applied as the knee was flexed from 0° to 90° at the baseline, and after distal resections of 2 mm, and 4 mm. Coronal laxity, defined as the sum of varus and valgus angulation in response to the applied varus and valgus torques, was measured at 30° and 45°of flexion, and the flexion angle was identified where the increase in laxity was the greatest with respect to baseline. Results. With 2 mm and 4 mm of distal femoral resection, the knee extended an additional 4°±0.5° and 8°±0.75°, respectively (Figure 2). No significant difference was found between the extension angle predicted by the six models and the results of the cadaveric study after 2 mm (p= 0.71) and 4 mm (p= 0.47). At 2 mm resection, mean coronal laxity increased by 3.1° and 2.7° at 30° and 45°of flexion, respectively. At 4 mm resection, mean coronal laxity increased by 6.5° and 5.5° at 30° and 45° of flexion, respectively (Figures 3a and 3b). The flexion angle corresponding to the greatest increase in coronal laxity for 2 mm of distal resection occurred at 22±7° of flexion with a mean increase in laxity of 4.0° from baseline. For 4 mm distal resection, the greatest increase in coronal laxity occurred at 16±6° of flexion with a mean increase in laxity of 7.8° from baseline. Conclusion. A TKA computational model representing a knee with preoperative flexion contracture was developed and corroborated measures from a previous cadaveric study [1]. While additional distal femoral resection in primary TKA increases passive knee extension, the consequent joint line elevation induced up to 8° of additional coronal laxity in mid-flexion. This additional midflexion laxity could contribute to midflexion instability; a condition that may require TKA revision surgery. Further studies are warranted to understand the relationship between joint line elevation, midflexion laxity, and instability. For any figures or tables, please contact the authors directly

Introduction. Surgeons commonly resect additional distal femur during primary total knee arthroplasty (TKA) to correct a flexion contracture. However, the effect of joint line proximalization on TKA kinematics is unclear. Thus, our goal was to quantify the effect of additional distal femoral resection on knee extension and mid-flexion laxity. Methods. Six computational knee models with TKA-specific capsular and collateral ligament properties were implanted with a contemporary posterior-stabilized TKA. A 10° flexion contracture was modeled to simulate a capsular contracture. Distal femoral resections of +2 mm and +4 mm were simulated for each model. The knees were then extended under standardized torque to quantify additional knee extension achieved. Subsequently, varus and valgus torques of ±10 Nm were applied as the knee was flexed from 0° to 90° at the baseline, +2 mm, and +4 mm distal resections. Coronal laxity, defined as the sum of varus and valgus angulation with respective torques, was measured at mid-flexion. Results. With +2 mm and +4 mm of distal femoral resection, the knee extended an additional 4°±0.5° and 8°±0.75°, respectively. At 30° and 45°of flexion, baseline laxity averaged 4.8° and 5.0°, respectively. At +2 mm resection, mean coronal laxity increased by 3.1° and 2.7° at 30° and 45°of flexion, respectively. At +4 mm resection, mean coronal laxity increased by 6.5° and 5.5° at 30° and 45° of flexion, respectively. Maximal increased coronal laxity for a +4 mm resection occurred at a mean 16° (range, 11–27°) of flexion with a mean increased laxity of 7.8° from baseline. Conclusion. While additional distal femoral resection in primary TKA increases knee extension, the consequent joint line elevation induces up to 8° of coronal laxity in mid-flexion in this computational model. As such, posterior capsular release prior to resecting additional distal femur to correct a flexion contracture should be considered

Total Knee Joint Replacement is mostly commonly performed using a measured resection technique. When the PCL is retained 9mm of bone is resected off the distal femur. If the PCL is excised 11m of bone is resected. Computer assisted total knee joint replacement will guide the surgeon to perform the optimal distal femoral resection to gain neutral alignment and full post operative extension. Three hundred TKJR’s were performed by one surgeon using the De Puy Ci navigation system. A ligament balancing technique is used whereby a neutral tibial resection is performed. A ligament tensor is inserted in extension and flexion. The navigation system then performs an optimization process whereby the distal femoral cut is calculated to give a neutral mechanical axis and 0° of knee extension. Data was collected measuring the distal femoral resection in the PCL retained and resected knees. The distal femoral cut required to achieve full extension for the PCL retaining TKJR ranged from 5 – 15mm. The mean was 11.2mm. The distal femoral cut required to achieve full extension for the PCL sacrificing TKJR ranged from 5 – 15mm. The mean was 10.8mm. There was no difference between the two groups (p=0.07). Both the PCL retaining and sacrificing TKJR distal resections correlated with the preoperative flexion deformity, i.e. patients with a greater fixed flexion deformity required a greater distal femoral resection to achieve full extension. There is a wide variation in the distal femoral cut to achieve full extension in TKJR. It is accepted that a smaller distal resection is required for a PCL retaining than a PCL sacrificing TKJR. Our study refutes this premise. A greater femoral resection is required if there is a greater fixed flexion deformity. A measured resection technique will result in a large percentage of patients with a fixed flexion deformity following TKJR

Distal femoral physeal fractures can cause of growth distrurbance which frequently requires further surgical intervention. The aim of this study was to determine if tibial tuberosity ossification at the time of injury can predict further surgery in patients who have sustained a physeal fracture of the distal femur. We retrospectively investigated all patients who had operative treatment for a distal femoral physeal fracture at a paediatric level one trauma center over a 17 year period. Logistic regression analysis was performed investigating associations between the need for further surgery to treat growth disturbance and tibial tuberosity ossification, age, Salter Harris grade, mode of fixation or mechanism of injury. 74 patients met the inclusion criteria. There were 57 boys (77%) and 17 girls (23%). The average age at time of injury was 13.1 years (range 2.-17.1 years). Following fixation, 30 patients (41%) underwent further surgery to treat growth disturbance. Absence of tibial tuberosity fusion to the metaphysis was significantly associated with need for further surgery (p = < 0 .001). Odds of requiring secondary surgery after tibial tuberosity fusion to metaphysis posteriorly (compared with not fused) were 0.12, 95% CI (0.04, 0.34). The estimate of effect of tibial tuberosity ossification on reoperation rates did not vary when adjusted for gender, mechanism, fixation and Salter Harris grade. When accounting for age, the odds of further operation if the tibial tuberosity is fused to the metaphysis posteriorly (compared with not fused) were 0.28, 95% CI (0.08, 0.94). Tibial tuberosity ossification stage at time of injury is a predictor of further surgery to treat growth disturbance in paediatric distal femoral fractures. Children with distal femoral physeal fractures whose tibial tuberosity was not fused to the metaphysis posteriorly were 8.3 times more likely to require further surgery

Abstract. Introduction. Distal Femoral Fractures around a Total Knee Replacement have a reported incidence of 0.25–2.3% of primary TKRs. Literature suggests that these fractures have high complication rates such as non union and revision. Methodology. A retrospective case note review was undertaken of all patients who sustained a distal femoral fracture around a TKR from April 2014-April 2021. Data parameters collected included patient demographics, classification of fracture, management, post op mobility, fracture union and mortality. Results. 52 distal femoral fractures were recorded, out of which 5 patients had bilateral fractures. The average age was 83.6 years (61–101). 41 fractures were managed operatively with 61% undergoing ORIF, 37% undergoing Distal Femoral Replacement & 2% undergoing a retrograde IM Nail. The median LOS was 22 days (11–85) for patients treated with DFR versus 10 (3–75) for those undergoing an ORIF. 60% of DFR patients were discharged home compared to 56% of those who underwent an ORIF. All the DFR patients were FWB post op compared to ORIF 24%. Conclusion. Over a 7 year study period, 52 distal femoral fractures were reviewed. Despite FWB status post op, patients undergoing a DFR had a longer length of stay and less were discharged home compared to the ORIF group. Given the cost of a distal femoral replacement (£4485-6500) compared to £212-297 for a locking plate, in order to get patients FWB post operatively potentially dual plating (medial and lateral) may need to be considered if the fracture is amenable to improve stability & allow FWB

Aims. Surgeons commonly resect additional distal femur during primary total knee arthroplasty (TKA) to correct a flexion contracture, which leads to femoral joint line elevation. There is a paucity of data describing the effect of joint line elevation on mid-flexion stability and knee kinematics. Thus, the goal of this study was to quantify the effect of joint line elevation on mid-flexion laxity. Methods. Six computational knee models with cadaver-specific capsular and collateral ligament properties were implanted with a posterior-stabilized (PS) TKA. A 10° flexion contracture was created in each model to simulate a capsular contracture. Distal femoral resections of + 2 mm and + 4 mm were then simulated for each knee. The knee models were then extended under a standard moment. Subsequently, varus and valgus moments of 10 Nm were applied as the knee was flexed from 0° to 90° at baseline and repeated after each of the two distal resections. Coronal laxity (the sum of varus and valgus angulation with respective maximum moments) was measured throughout flexion. Results. With + 2 mm resection at 30° and 45° of flexion, mean coronal laxity increased by a mean of 3.1° (SD 0.18°) (p < 0.001) and 2.7° (SD 0.30°) (p < 0.001), respectively. With + 4 mm resection at 30° and 45° of flexion, mean coronal laxity increased by 6.5° (SD 0.56°) (p < 0.001) and 5.5° (SD 0.72°) (p < 0.001), respectively. Maximum increased coronal laxity for a + 4 mm resection occurred at a mean 15.7° (11° to 33°) of flexion with a mean increase of 7.8° (SD 0.2°) from baseline. Conclusion. With joint line elevation in primary PS TKA, coronal laxity peaks early (about 16°) with a maximum laxity of 8°. Surgeons should restore the joint line if possible; however, if joint line elevation is necessary, we recommend assessment of coronal laxity at 15° to 30° of knee flexion to assess for mid-flexion instability. Further in vivo studies are warranted to understand if this mid-flexion coronal laxity has negative clinical implications. Cite this article: Bone Joint J 2021;103-B(6 Supple A):87–93

Introduction. Previous anthropometric studies have reported gender differences in distal femoral morphology. After total knee arthroplasty, females have a higher prevalence of medial or lateral femoral component overhang, which could be responsible for postoperative knee pain and decreased range of motion. Consequently, gender-specific knee prostheses were designed to accommodate female morphology. However, to date, very few studies have investigated the knee morphology of Japanese adults and possible gender differences. The purpose of this study was to examine the distal femoral morphology of Japanese patients, to characterize anatomical differences between men and women, and to evaluate the need to create gender-specific knee prostheses. Material and Methods. We evaluated 107 knees in 17 male and 90 female Japanese patients for total knee arthroplasty (TKA)[fig.1]. The medial-lateral (ML) and anteroposterior (AP) dimensions of the knees at different levels evaluated intraoperative measurement, and ML/AP aspect ratios were calculated. Results. On the distal femoral cut surface, the mean ML widths were 74.8 mm for men and 65.5 mm for women. Such values were generally smaller compared to data from European and North American studies. In this study, the mean ML/AP aspect ratios were 1.21 for men and 1.13 for women, higher than those from non-Asian regions. The ML/AP ratios of Japanese patients were negatively correlated with distal femoral AP length. Discussion. The dimensions and sizes of the human femur have been reported in the literature, as measured by dissection of cadaver knees, plain radiographs or CT scans of living subjects, or other means. Compared to data on knees from European and North American populations, femoral ML/AP ratios were smaller for a given AP length in Japanese individuals. In addition, the mean AP and ML distances of the distal femur of Japanese individuals were smaller than those of Western populations, which could be associated with differences in height or other physical and skeletal characteristics. Several studies reported significant gender difference in the ML/AP ratio. Because of the shapes of the distal femur were more trapezoidal for women and more rectangular for men. After TKA, females have a higher prevalence of medial or lateral femoral component overhang, which could be responsible for postoperative knee pain and decreased range of motion. Our results suggest that gender-specific knee prostheses may prevent such postoperative complications. Conclusions. Japanese women had a relatively narrower femoral width for a given AP length than men. Our study suggests the utility of Japanese-specific implants and provides useful insights for manufacturers to design components of appropriate sizes and aspect ratios for Japanese TKA patients

Lower limb mal-alignment due to deformity is a significant cause of early degenerative change and dysfunction. Standard techniques are available to determine the centre of rotation of angulation (CORA) and extent of the deformities. However, distal femoral deformity is difficult to assess because of the difference between anatomic and mechanical axes. We describe a novel technique which accurately determines the CORA and extent of distal femoral deformity. Using standard leg alignment views of the normal femur, the distal femoral metaphysis and joint line are stylised as a block. A line bisecting the anatomical axis of the proximal femur is then extended distally to intersect the joint. The angle (?) between the joint and the proximal femoral axis, and the position (p) where the extended proximal femoral axis intersects the joint line are calculated. These measurements can then be reproduced on the abnormal distal femur in order to calculate the CORA and extent of deformity, permitting accurate correction. We examined the utility and reproducibility of the new method using 100 normal femora. We found this technique to be universally robust in a variety of distal femoral deformities

Lower limb mal-alignment due to deformity is a significant cause of early degenerative change and dysfunction. Standard techniques are available to determine the centre of rotation of angulation (CORA) and extent of the majority of deformities, however distal femoral deformity is difficult to assess because of the difference between anatomic and mechanical axes. We found the described technique involving constructing a line perpendicular to a line from the tip of the greater trochanter to the centre of the femoral head inaccurate, particularly if the trochanter is abnormal. We devised a novel technique which accurately determines the CORA and extent of distal femoral deformity, allowing accurate correction. Using standard leg alignment views of the normal femur, the distal femoral metaphysis and joint line are stylized as a block. A line bisecting the axis of the proximal femur is then extended distally to intersect the joint. The angle (θ) between the joint and the proximal femoral axis and the position (p) where the extended proximal femoral axis intersects the joint line are calculated. These measurements can then be reproduced on the abnormal distal femur in order to calculate the CORA and extent of the deformity, permitting accurate correction. We examined the utility and reproducibility of the new method using 100 normal femora. θ = 81 ± sd 2.5°. As expected, θ correlated with femoral length (r=0.74). P (expressed as the percentage of the distance from the lateral edge of the joint block to the intersection) = 61% ± sd 8%. P was not correlated with θ. Intra-and inter-observer errors for these measurements are within acceptable limits and observations of 30-paired normal femora demonstrate similar values for θ and p on the two sides. We have found this technique to be universally applicable and reliable in a variety of distal femoral deformities

Fixed flexion contracture is often present in association with osteoarthritis of the knee and correction is one of the key surgical goals in total knee replacement. Surgical strategies to correct flexion contracture include removal of posterior osteophytes, posterior capsular release and additional distal femoral bone resection. Traditional teaching indicates 2 mm of additional distal femoral bone resection will correct 10 degrees of flexion deformity. However some studies have questioned this figure and removing excessive distal femoral bone results in elevation of the joint line, potentially causing patella baja, alteration in collateral ligament tension through the flexion arc and mid-flexion instability. The aim of our study is to determine the relationship between distal bone resection of the femur and passive knee extension in total knee arthroplasty. A cohort of 50 patients, undergoing total knee arthroplasty, was recruited. Following complete femoral and tibial bone preparation, to simulate the effect of distal femoral bone resection, augments of 2 mm increments (2 mm, 4 mm, 6 mm, 8 mm) were placed onto the trial femoral component. The degree of flexion contracture with each augment was measured using computer navigation. The results showed a 2 mm augment produced an average of 3.37 degrees of flexion deformity. A 4 mm augment led to an average of 6.68 degrees fixed flexion, whilst a 6 mm augment produced 11.38 degrees. To correct 10 degrees flexion deformity, an additional 6 mm distal femoral bone resection is required. In conclusion, additional distal femoral bone resection may not be as an effective strategy as previously believed to correct fixed flexion deformity in total knee arthroplasty

Lower limb mal-alignment due to deformity is a significant cause of early degenerative change and dysfunction. Standard techniques are available to determine the centre of rotation of angulation (CORA) and extent of the majority of deformities, however distal femoral deformity is difficult to assess because of the difference between anatomic and mechanical axes. We found the described technique involving constructing a line perpendicular to a line from the tip of the greater trochanter to the centre of the femoral head inaccurate, particularly if the trochanter is abnormal. We devised a novel technique which accurately determines the CORA and extent of distal femoral deformity, allowing accurate correction. Using standard leg alignment views of the normal femur, the distal femoral metaphysis and joint line are stylized as a block. A line bisecting the axis of the proximal femur is then extended distally to intersect the joint. The angle (Θ) between the joint and the proximal femoral axis and the position (p) where the extended proximal femoral axis intersects the joint line are calculated. These measurements can then be reproduced on the abnormal distal femur in order to calculate the CORA and extent of the deformity, permitting accurate correction. We examined the utility and reproducibility of the new method using 100 normal femora. Θ = 81 ± sd 2.5. As expected, Θ correlated with femoral length (r=0.74). P (expressed as the percentage of the distance from the lateral edge of the joint block to the intersection) = 61% ± sd 8%. P was not correlated with Θ. Intra-and inter-observer errors for these measurements are within acceptable limits and observations of 30-paired normal femora demonstrate similar values for Θ and p on the two sides. We have found this technique to be universally applicable and reliable in a variety of distal femoral deformities

Introduction. Optimal alignment and position of implants is an important goal In TKA. Conventional mechanical instruments use the anatomic axis and “average” anatomy to position the femoral component to achieve acceptable mechanical limb alignment. Numerous studies have documented the frequency of TKA outliers (+/− 3 degrees) to be 30% or more. The purpose of this study was to determine the “true” distal femoral valgus angle of the femur. Methods. 13,586 CT scans of patients undergoing TKA with patient specific instruments were analyzed. Three-dimensional reconstructions were performed and the distal femoral anatomic and mechanical axes were measured digitally. The distal femoral valgus angle was defined and the difference between the anatomic and mechanical axes of the distal femur. Results. The average distal femoral valgus angle was 5.7 +/− 2.3 degrees. The range was one-degree varus to 16 degrees valgus. 13.8% of patients had greater than 9 or less than 3 degrees of femoral valgus. Conclusion. The anatomy of the distal femur is highly variable in patients undergoing TKA. Routine use of anatomic based instruments and average distal femoral valgus angular resections can lead to errors in resultant mechanical limb alignment in a significant number of patients undergoing TKA

Purpose; To show that Distal Femoral Endoprosthetic Replacement for metastatic disease can be performed with relatively few complications and allows good pain control and mobilisation for otherwise severely compromised patients. Method; This is a retrospective study, using the oncology database, patient records and local correspondence, looking at 23 patients with distal femoral metastases who had limb salvage with a Distal Femoral Endoprosthesis (DF EPR). Results; There were 10 males (43%) and 13 females (57%), mean age 65 (38–84). 13 (57%) had Renal, 6 (26%) Breast and 5 other primaries identified. Five had additional metastases. 8 (35%) had pathological fractures. The mean time for diagnosis of mets was 67 months ranging from 0 (i.e. at the time of primary tumour) to 30 years since the original diagnosis. 15 patients had surgery alone. 3 patients were lost to follow up. 15 patients have diseased at a mean of 26 months (4–58) post op. There was one intra-op and four post-op complications. The majority of the patients were satisfied post op with regards to pain and mobility. The generally unfavourable prognosis and perceived risks have led surgeons to palliate, stabilise in situ or amputate for distal femoral metastases despite recognised morbidity and life style restrictions. We conclude that DF EPR should be considered as a limb salvage option in patients with distal femoral mets

The routine use of a fixed distal femoral resection angle in total knee arthroplasty (TKA) assumes little or no variation in the angle between the anatomical and mechanical femoral axes (FMA angle) in different patients. The aims of this study were threefold, firstly to investigate the distribution of FMA angle in TKA patients, secondly to identify any correlation between the FMA angle and the pre-operative coronal mechanical femoro-tibial (MFT) angle and in addition to assess post-operative MFT angle with fixed or variable distal femoral resection angles. 277 primary TKAs were performed using either fixed or variable distal femoral resection angles (174 and 103 TKAs respectively), with intramedullary femoral and extramedullary tibial jigs. The variable distal femoral resection angles were equal to the FMA angle measured on pre-operative Hip-Knee-Ankle (HKA) digital radiographs for each patient. Outcomes were assessed by measuring the FMA angle and the pre- and post-operative MFT angles on HKA radiographs. The FMA angle ranged from 2° to 9° (mean 5.9°). Both cohorts showed a correlation between FMA and pre-operative MFT angles (fixed: r = -0.499, variable: r = -0.346) with valgus knees having lower FMA angles. Post-operative coronal alignment within ±5° increased from 86% in the fixed angle group to 96% when using a variable angle, p = 0.025. For post-operative limb alignment within ±3°, accuracy improved from 67% (fixed) to 85% (variable), p = 0.002. These results show that the use of a fixed distal femoral resection angle is a source of error regarding post-operative coronal limb malalignment. The correlation between the FMA angle and pre-operative varus-valgus alignment supports the rational of recommending the adjustment of the resection angle according to the pre-operative deformity (3°-5° for valgus, 6°-8° for varus) in cases where HKA radiographs are not available for pre-operative planning

Lower limb mal-alignment due to deformity is a significant cause of early degenerative change and limb dysfunction. Standard techniques are available to determine the centre of rotation of angulation (CORA) and extent of the majority of deformities, however distal femoral deformity is difficult to assess because of the difference between the anatomic and mechanical axes. We have found the described technique involving constructing a line perpendicular to a line from the tip of the greater trochanter to the centre of the femoral head inaccurate, particularly if the trochanter is abnormal. We have devised a novel technique which accurately determines the CORA and extent of distal femoral deformity, allowing accurate correction. Using standard leg alignment views of the normal femur, the distal femoral metaphysis and joint line are stylised as a block. A line bisecting the axis of the proximal femur is then extended distally to intersect the joint. The angle (𝛉) between the joint and the proximal femoral axis and the position (p) where the extended proximal femoral axis intersects the joint line are calculated. These measurements can then be reproduced on the abnormal distal femur in order to calculate the CORA and extent of the deformity, permitting accurate correction. We have examined the utility and reproducibility of the new method using one hundred normal femurs. Θ=81+/− sd 2.5°. As expected, 𝛉 correlated with femoral length (r=0.74). P (expressed as the percentage of the distal from the medial edge of the joint block to the intersection) = 61% +/− sd 8%. P was not correlated with 𝛉. Intra-and inter-observer errors for these measurements are within acceptable limits and observations of twenty paired normal femora demonstrate similar values for 𝛉 and p on the two sides. We have employed this technique in a variety of distal femoral deformities, including vitamin D resistant rickets, growth arrest, fibula hemimelia, post-traumatic deformity and Ellis-van Creveld syndrome. We find the system universally applicable and reliable

Aims. The impact of a diaphyseal femoral deformity on knee alignment varies according to its severity and localization. The aims of this study were to determine a method of assessing the impact of diaphyseal femoral deformities on knee alignment for the varus knee, and to evaluate the reliability and the reproducibility of this method in a large cohort of osteoarthritic patients. Methods. All patients who underwent a knee arthroplasty from 2019 to 2021 were included. Exclusion criteria were genu valgus, flexion contracture (> 5°), previous femoral osteotomy or fracture, total hip arthroplasty, and femoral rotational disorder. A total of 205 patients met the inclusion criteria. The mean age was 62.2 years (SD 8.4). The mean BMI was 33.1 kg/m. 2. (SD 5.5). The radiological measurements were performed twice by two independent reviewers, and included hip knee ankle (HKA) angle, mechanical medial distal femoral angle (mMDFA), anatomical medial distal femoral angle (aMDFA), femoral neck shaft angle (NSA), femoral bowing angle (FBow), the distance between the knee centre and the top of the FBow (DK), and the angle representing the FBow impact on the knee (C’KS angle). Results. The FBow impact on the mMDFA can be measured by the C’KS angle. The C’KS angle took the localization (length DK) and the importance (FBow angle) of the FBow into consideration. The mean FBow angle was 4.4° (SD 2.4; 0 to 12.5). The mean C’KS angle was 1.8° (SD 1.1; 0 to 5.8). Overall, 84 knees (41%) had a severe FBow (> 5°). The radiological measurements showed very good to excellent intraobserver and interobserver agreements. The C’KS increased significantly when the length DK decreased and the FBow angle increased (p < 0.001). Conclusion. The impact of the diaphyseal femoral deformity on the mechanical femoral axis is measured by the C’KS angle, a reliable and reproducible measurement. Cite this article: Bone Jt Open 2023;4(4):262–272

Distal femoral physeal fractures in children have a high incidence of physeal arrest, occurring in a mean of 40% of cases. The underlying nature of the distal femoral physis may be the primary cause, but other factors have been postulated to contribute to the formation of a physeal bar. The purpose of this study was to assess the significance of contributing factors to physeal bar formation, in particular the use of percutaneous pins across the physis. We reviewed 55 patients with a median age of ten years (3 to 13), who had sustained displaced distal femoral physeal fractures. Most (40 of 55) were treated with percutaneous pinning after reduction, four were treated with screws and 11 with plaster. A total of 40 patients were assessed clinically and radiologically after skeletal maturity or at the time of formation of a bar. The remaining 15 were followed up for a minimum of two years. Formation of a physeal bar occurred in 12 (21.8%) patients, with the rate rising to 30.6% in patients with high-energy injuries compared with 5.3% in those with low-energy injuries. There was a significant trend for physeal arrest according to increasing severity using the Salter-Harris classification. Percutaneous smooth pins across the physis were not statistically associated with growth arrest

Background. Thigh pain following a well-fixed total hip arthroplasty (THA) remains problematic and a source of patient dissatisfaction. The purpose of this study is to evaluate if the development of distal femoral cortical hypertrophy (DFCH) is associated with chronic postoperative thigh pain after THA with a short stem implant. Methods. All patients who underwent an uncomplicated primary THA via a direct anterior approach with the short stem Taperloc Microplasty® (Zimmer Biomet, Warsaw, IN) implant between 2011 and 2015 were mailed a pain drawing questionnaire. Radiographs were reviewed at 1-year minimum to determine cortical thickness change from immediate post-op. Thigh pain was compared to DFCH as well as patient demographics and femoral stem size. 293 patients were included in the study. Results. Mean follow-up was 3.2 years. A total of 218 hips (74%) had cortical hypertrophy in Gruen zone 3 and 165 hips (56%) had cortical hypertrophy in Gruen zone 5. Fifty-two hips (18%) had ≥25% cortical hypertrophy in zone 3 and 91 hips (31%) had ≥25% cortical hypertrophy in zone 5. A total of 44 patients (15%) reported anterior thigh pain and 43 patients (15%) reported lateral thigh pain. Development of DFCH in either Gruen zone 3 or 5 was not associated with anterior or lateral thigh pain. Stem size was positively correlated with zone 3 hypertrophy and inversely related to zone 5 hypertrophy. Thigh pain was not associated with patient age, gender, activity level or stem size. Conclusion. The development of distal femoral cortical hypertrophy after THA with a short stem implant was high, but not associated with patient reported anterior or lateral thigh pain. For any tables or figures, please contact the authors directly

Purpose. Many TKA instruments were developed in these days. Distal femoral cutting guide using intra-medullary system were divided into two methods, from anterior or medial. Many companies employed anterior cutting guide, however these guides have a disadvantage of wide skin and quadriceps incision. Only Zimmer provided medial cut guide which performed short skin and quadriceps incision. However, reference point (medial femoral condyle) will be a risk of imprecise cutting for a medial condyle defect cases. We tried L-shaped new distal femoral cutting guide, reference point will be both femoral condyle and cutting from antero-medial side. The purpose of this study was to prove usefulness of the new guide. Materials and Methods. Twenty-nine knees were employed in this study. All knees were treated with Optetrak knee system (Exactec). Surgical methods were as follows, mid line skin incision, short para-patellar deep incision, no patellar resurfacing, PS type implant and cement fixation were employed. 13 knees were used original anterior cutting guide (O group) and 16 knees were used new antero-medial cut guide (N group). Study items were length of skin incision, length of Quadriceps incision, surgical time, JOA score, and component tilting angles (implant position were compared to femoral axis with AP and lateral view of roentgenograms). Results. Average skin incision was 11.7cm in O group and 10.6cm in N group. Average Quadriceps incision was 4.1cm in O group and 2.9cm in N group. There were significant difference in length of skin incision and length of Quadriceps incision. Average surgical time was 155min in O group and 147min in N group. Average component angles of AP view were 84 deg. in O group and 83 deg. in N group. Average component angles of lateral view were 99 deg. in O group and 99 deg. in N group. There were no significant differences between O group and N group in surgical time, component angles, amount of bleeding, and post surgical JOA scores. Conclusions. New distal femoral cutting guide demonstrated same precise cutting compared to original guide. New distal femoral cutting guide achieved small skin incision and small quadriceps incision which is useful for MIS-TKA

In Total Knee Arthroplasty (TKA) restoring the mechanical alignment of the knee joint is essential. This can be improved by considering the individual variability in the angle between the mechanical and anatomical axes of the femur (FMA angle). However with the traditional instrumentation and the use of the most common fixed distal femoral resection angle of 6° we assume little or no variation in the FMA angles in different patients. In a previous study we showed that the FMA angle had a wide distribution and that there was a good correlation between the FMA angle and the pre-operative lower limb alignment in the coronal plane. Our hypothesis was that improved post operative limb alignment would be achieved with traditional instrumentation by individual measurement of the FMA angles pre-operatively and adjusting the distal femoral resections accordingly. In the study we compared the post-operative coronal limb alignment for a cohort of patients with a variable distal femoral resection angle to the previous cohort of fixed distal femoral resection angle. The study consisted of 103 patients undergoing 103 consecutive primary TKAs between October 2008 and March 2009. All patients had pre- and post-operative Hip-Knee-Ankle digital radiographs and had TKAs performed using a variable distal femoral cut angle. The FMA angle and the mechanical femoro-tibial (MFT) angles were measured in all cases. Inter-observer variation was measured by second observer readings. We compared our results with the group of 158 consecutive patients undergoing 174 primary TKAs operated between January and October 2007 using fixed distal femoral resection angle. Patient demographics of the two cohorts (age, gender, BMI) were similar. The pre-operative coronal deformity for the variable cohort was less than the fixed, mean 3.7° varus (SD 5.8°) compared to 4.7° varus (SD 7.9°). The FMA angles for the variable cohort ranged from 4° to 8°, (the fixed cohort from 2° to 9°). The variable valgus resection angles cohort showed a correlation between FMA and pre-operative MFT angles as had previously been shown in the fixed cohort (r = −0.499 and r = −0.346 respectively). Post op alignment showed that accuracy within ±5° increased from 86% (fixed resection angle group) to 96% (variable resection group). When using the more commonly quoted accuracy of within ±3°, this changed from 67% (fixed resection angle group) to 85% (variable resection group). These improvements were statistically significant (chi-squared 0.025 and 0.002, respectively). To further evaluate the effect of using variable angles we analysed the improvement of each of the different groups of deformity identified in the previous study (> 8° varus, 8° varus to 1° valgus, > 2° valgus). The range was reduced in both the extreme varus and valgus groups with the variable angles. The most significant improvement was found in the valgus group with the median reducing from 3° to 2° and range from 14° to 8°. It seems logical to use a variable distal femoral resection angle based on the patient’s individual anatomy. By doing so, our results show significant improvement of postoperative limb alignment compared to traditional method of using fixed distal femoral resection angle. In units where preoperative long leg film radiographs are available, measuring the FMA angle and setting the distal femoral resection angle guide accordingly improves the postoperative limb alignment. However, where long leg radiographs are not available, changing the distal femoral resection angle according to the pre-operative varus-valgus deformity is likely to improve the post operative limb alignment. (e.g. 4°–5° distal femoral resection angle for preoperative valgus, 6° for preoperative mild/moderate varus, and 7°–8° for preoperative severe varus).Computer navigation, however, enables us not only to use customised distal femoral cut for each patients, but it also provides many other useful information such as dynamical limb alignment through motion, component rotation, soft tissue balancing

Purpose of study: The majority of children with cerebral palsy suffer from fixed flexion contractures of their knees. Procedures commonly used to correct these deformities include hamstring releases, anterior femoral hemi-epiphyseodesis and femoral extension osteotomies. The latter procedure can cause neurovascular complications. Femoral stapling procedures are unpopular because of the risk of permanent physeal closure. Soft tissue procedures are usually only partially effective, with a high recurrence rate. We present our initial experience of correcting of knee flexion deformities using the 8-plate technique which uses guided growth in the distal femoral physis to achieve gradual correction of the knee flexion deformity. Method: The case notes of patients who underwent an anterior distal femoral hemi-epiphyseodesis using the 8-plate technique between April 2005 and August 2006 were analysed. A total of 18 limbs in 12 patients underwent this procedure. The pre- and post-operative flexion deformity was measured with a goniometer. Results: The mean age of the patients was 12.8 years (range 9–16) and the mean follow up was 8.5 months (range 3–15). The mean correction achieved was 16.15 degrees (range 5–40). Conclusions: This is a simple technique with a learning curve of 1 case and with few complications to date. All patients in our series have shown sustained gradual correction. We also present technical tips in the use of the 8-plate for anterior femoral hemi-epiphyseodesis

We report the use of contained impacted morsellized allograft to revise an aseptically loose, massive distal femoral endoprosthetic replacement in a 27-year old Caucasian lady. The prosthesis was inserted 4 years earlier, following neo-adjuvant chemotherapy and resection of a distal femoral high grade osteosarcoma. Impaction grafting was used to restore bone stock and maintain femoral length. The patient remains disease-free, with excellent function, at two years after revision with no evidence of loosening and maintenance of bone stock. This is the first time this technique has been used in revision of a distal femoral endoprosthetic replacement

Introduction & aims. Different racial groups show variations in femoral morphometry. Femoral anteroposterior measurement and mediolateral measurement are key variables in designing femoral implant for TKR. Their aspect ratio determines the shape and mediolateral sizing for the proper patellofemoral tracking and uniform stress distribution over the resected distal femoral surface. Method. We reviewed the current literature in December 2013 in common medical databases including the Cochrane Library, PubMed and Medline. Keywords included combinations of: Anthropometry, Knee, Arthroplasty, Femur, Morphometry, Geometry. We selected papers including femoral morphometric data collected from populations of different ethnic origins. Papers covered populations in the USA, China, Germany, Thailand, Korea, India, Japan and Malaysia. Results. We have analysed femoral morphometry variables among different ethnic groups from the available data. Gross size of the resected femur can be defined in terms of antero-posterior (AP) and medio-lateral (ML) dimensions, an in the aspect ratio of femoral medio-lateral to femoral antero-posterior dimensions (fML/fAP). The Korean population showed the least value of fAP among all the groups, followed by Thai, Japanese, Indian, Malaysian and Chinese showing the increasing order among the sub-groups of Asian Population. American population shows the next higher fAP measurements from Asian population. German follows, and Arab quantify the largest value of this femoral anthropometric variable. fML varies by huge difference among male and female data in all populations. Thai, Indian, Malaysian, Arab, Japanese, Korean, German, Chinese and American; this sequence is the increasing order of fML. More trapezoid-shaped and narrower ML, this variation in female group leads to over-hang the implant for a given fAP. Generally, the aspect ratios are measured higher in these smaller female knees, and lower in larger male knees. Conclusions. Anthropometric data measuring distal femoral segment in different ethnic groups shows that the Asian population requires custom-fit implant design based on the morphological data. It would be more appropriate to introduce several medio-lateral options in sizing the implant for given antero-posterior dimensions

A technical goal in total knee arthroplasty is the production of a neutral coronal plane mechanical axis. Errors may produce large mechanical axis deviations precipitating early implant failure. This study sought to test if measured distal femoral resection produced more accurate and consistent coronal alignment than arbitrarily set distal femoral resection. Data from a cohort of 255 consecutive unselected primary total knee arthroplasties undertaken by the senior author (PM) was collected prospectively and independently assessed. In the first 167 cases distal femoral resection was arbitrarily set to 5 degrees of valgus. In the remaining 88 cases the distal femoral resection angle was determined on a preoperative long leg standing AP radiograph. Postoperative coronal alignment was measured on long leg standing AP radiograph in all cases. The measured distal femoral valgus angle was between 4 and 7 degrees. An equal number measured either 5 or 6 degrees and accounted for 85% of the total number. Statistically insignificant improvements in mean axis and standard deviation were observed in the measured group: mean axis deviation −0.31 vs −0.51: p=0.17 (independent samples t test) and standard deviation 0.91 vs 1.09: p=0.055 (Levene test). Acceptable coronal alignment in total knee arthroplasty can reliably be obtained with conventional instrumentation. Improvement in standard deviation with measured distal femoral valgus angle approaches statistical significance

We report a case of spontaneous physeal growth arrest of the distal femur in a nine-year-old child with Ewing’s sarcoma of the proximal femur treated with chemotherapy and endoprosthetic replacement. Owing to the extent of disuse osteoporosis at the time of surgery, the entire intramedullary canal up to the distal femoral physis was filled with cement. Three years later, the femur remained at its pre-operative length of 19 cm. Pre-operative calculations of further growth failed to account for the growth arrest, and the initial expandable growing prosthesis inserted has been revised to a longer one in order to address the leg-length discrepancy. To our knowledge, this is the only reported case of distal femoral physeal growth arrest following cemented endoprosthetic replacement of the proximal femur

Purpose. The undulating pattern of the distal femur is well recognized. Radiographs do not always represent the full extent of the undulations. With recent increasing use of guided growth technique in the distal femur, it is important to define safe zones for screw placement. Method. We performed an anatomical study on 26 cadaveric distal femoral epiphyses, ages 3–18 years. High resolution three-dimensional surface scans were obtained with a laser scanner, and were analyzed to determine the absolute height of the central physeal ridge, and the central physeal ridge height with respect to the highest points medially and laterally. Results. The average height of the central physeal ridge was 5.5mm (range 2.9–9.8mm) with respect to the lowest point on the physis. When normalized to the size of the physis, both the height and surface area of the central physeal ridge decreased with increasing age. The amount that the central peak protruded superior to a line from the medial to lateral physeal edges is shown. In all specimens ages 13 years and older the central peak was below the medial-lateral line, in specimens ages 8–12 years it was no more than 4mm above the line, and in specimens under 8 years it was no more than 8mm above the line. Conclusion. The central physeal ridge is the major structure within the distal femoral physis. In patients 13 years and older the medial-lateral physeal line defines a safe zone one should stay above to avoid screw penetration into the central physis. In patients ages 8–12 years one should stay 4mm above the medial-lateral line, and in patients 8 years and under one should stay 8mm above the line

Background. Hip fracture care has evolved, largely due to standardisation of practice, measurement of outcomes and the introduction of the Best Practice Tariff, leading to the sustained improvements documented by the National Hip Fracture Database (NHFD). The treatment of distal femoral fractures in this population has not had the same emphasis. This study defines the epidemiology, current practice and outcomes of distal femoral fractures in four English centres. Methods. 105 patients aged 50 years or greater with a distal femoral fracture, presenting to four UK major trauma centres between October 2010 and September 2011 were identified. Data was collected using an adapted NHFD data collection tool via retrospective case note and radiograph review. Local ethics approval was obtained. Results. Mean age was 77 years (range 50–99), with 86% female. 95% of injuries were sustained from a low energy mechanism, and 72% were classified as either 33-A1 or 33-C1. The mean Parker mobility score and Barthel Independence Index were 5.37 (0–9) and 75.5 (0–100) respectively. Operative management was performed in 84%, and 86% had their surgery within 36 h. Three quarters were fixed with a peri-articuar locking plate. There was no consensus on post operative rehabilitation, but no excess of complications in the centres where weight bearing as tolerated was the standard. 45% were seen by an orthogeriatrician during their admission. Mean length of stay was 29 days. Mortality at 30 days, 6 months, and 1 year was 7%, 16% and 18% respectively. Conclusions. This study demonstrates that the distal femoral and hip fracture populations are similar, and highlights the current disparity in their management. The metrics and standards of care currently applied to hip fractures should be applied to the treatment of distal femoral fractures. Optimal operative treatment and rehabilitation remains unclear, and further research is in progress. Level of evidence. 2b. Ethics. Local approval was obtained

Aims. While mechanical alignment (MA) is the traditional technique in total knee arthroplasty (TKA), its potential for altering constitutional alignment remains poorly understood. This study aimed to quantify unintentional changes to constitutional coronal alignment and joint line obliquity (JLO) resulting from MA. Methods. A retrospective cohort study was undertaken of 700 primary MA TKAs (643 patients) performed between 2014 and 2017. Lateral distal femoral and medial proximal tibial angles were measured pre- and postoperatively to calculate the arithmetic hip-knee-ankle angle (aHKA), JLO, and Coronal Plane Alignment of the Knee (CPAK) phenotypes. The primary outcome was the magnitude and direction of aHKA, JLO, and CPAK alterations. Results. The mean aHKA and JLO increased by 0.1° (SD 3.4°) and 5.8° (SD 3.5°), respectively, from pre- to postoperatively. The most common phenotypes shifted from 76.3% CPAK Types I, II, or III (apex distal JLO) preoperatively to 85.0% IV, V, or VI (apex horizontal JLO) postoperatively. The proportion of knees with apex proximal JLO increased from 0.7% preoperatively to 11.1% postoperatively. Among all MA TKAs, 60.0% (420 knees) were changed from their constitutional alignments into CPAK Type V, while 40.0% (280 knees) either remained in constitutional Type V (5.0%, 35 knees) or were unintentionally aligned into other CPAK types (35.0%; 245 knees). Conclusion. Fixed MA targets in TKA lead to substantial changes from constitutional alignment, primarily a significant increase in JLO. These findings enhance our understanding of alignment alterations resulting from both unintended changes to knee phenotypes and surgical resection imprecision. Cite this article: Bone Jt Open 2024;5(2):109–116

PURPOSE. Lateral osteoarthritis of the valgus knee is a challenging problem, especially for young and active patients, where prosthetic replacement is not indicated. The purpose of the present study is to evaluate clinically and radiographically 91 patients with valgus knee treated with distal femoral varus osteotomy in mid and long term follow-up. METHODS. A clinical retrospective evaluation based on IKDC, OXFORD and WOMAC scores of 91 patients at 4 to 10 years of follow-up was performed. Subjective evaluation was based on a VAS for pain self-assessment. Radiographic evaluation was performed by an independent observer of all 91 patients at 2 to 6 years of follow-up. A survival analysis was performed assuming revision for any reason as primary endpoint. RESULTS. The present study reported a marked improvement in clinical score at a mean 8,3 years of follow-up with statistical significance (p<0.005). The radiographic evaluation revealed a reduction of 7,0° and 4,2° of FTA and HKA angles respectively (p<0.05) at a mean follow up of 4,3 years, while small differences were observed with TPA and PTS angles. The 8-years treatment survivorship was 95,6%. CONCLUSIONS. The present study demonstrates that distal femoral varus osteotomy is an effective and reliable option to manage lateral tibio-femoral compartment early degenerative joint disease in young- to middle-age patients, providing a satisfactory clinical improvement at a mean follow-up of 8 years. Furthermore, its survivorship at 8-years follow-up is over 95%

We used a knee-sparing distal femoral endoprosthesis in young patients with malignant bone tumours of the distal femur in whom it was possible to resect the tumour and to preserve the distal femoral condyles. The proximal shaft of the endoprosthesis had a coated hydroxyapatite collar, while the distal end had hydroxyapatite-coated extracortical plates to secure it to the small residual femoral condylar fragment. We reviewed the preliminary results of this endoprosthesis in eight patients with primary bone tumours of the distal femur. Their mean age at surgery was 17.years (14 to 21). The mean follow-up was 24 months (20 to 31). At final follow-up the mean flexion at the knee was 102° (20° to 120°) and the mean Musculoskeletal Tumour Society score was 80% (57% to 96.7%). There was excellent osteointegration at the prosthesis-proximal bone interface with formation of new bone around the hydroxyapatite collar. The prosthesis allowed preservation of the knee and achieved a good functional result. Formation of new bone and remodelling at the interface make the implant more secure. Further follow-up is required to determine the long-term structural integrity of the prosthesis

INTRODUCTION. Although the most commonly used method of femoral component alignment in total knee arthroplasty (TKA) is an intramedullary (IM) guides, this method demonstrated a limited degree of accuracy. The purpose of this study was to assess whether a portable, accelerometer-based surgical navigation system (Knee Align 2 system; Orth Align, Inc, Aliso Viejo, Calif) improve accuracy of the post-operative radiographic femoral component alignment compared to conventional IM alignment guide. MATERIALS & METHODS. Since February 2014, 44 consecutive patients (39 female, 5 male) with primary arthritis of the knee were enrolled in this prospective, randomized controlled study. 24 patients underwent TKA (Vanguard RP or PS, Biomet Japan) using the navigation device for the distal femoral resection (Navigated Group), and 20 patients with conventional femoral IM alignment guide. The proximal tibial resection was performed using an extramedullary guide. All the operation was performed by a single senior surgeon (YK) with the same gap balancing technique except for the use of the navigation system for the femur. Accuracy of femoral implant positioning was evaluated on 2 weeks postoperative standing anteroposterior (AP) hip to ankle radiographs. RESUTS. In the navigated group, 100% of patients had an alignment within 90 ± 3° to the femoral mechanical axis in the coronal plane, versus 90.0% in the IM guides cohort (Fig). The mean absolute difference between the intraoperative goal and the postoperative alignment was 0.79 ± 1.0° in the Knee Align 2 cohort, and 1.72 ± 1.6° in the IM guides cohort (P < 0.05). There was a difference in the standard deviations observed for the navigated cases and the conventional cases when femoral component position was considered. There were no technique specific complications associated with the navigation system. DISCUSSION & CONCLUSION. The distal femoral resection has been the main source of error as for the neutral mechanical axis because of the difficulty in visualization and detection of the center of the femoral head. The results in the current study have shown that a portable, accelerometer-based navigation device (Knee Align 2 system) significantly decreases outliers in femoral component alignment compared to conventional IM alignment guides in TKA

Peri-prosthetic fractures above a TKA are becoming increasingly more common, and typically occur at the junction of the anterior flange of the femoral component and the osteopenic metaphyseal distal femur. In the vast majority of cases the TKA is well fixed and has been functioning well prior to fracture. For loose components, revision is typically indicated. Often, distal femoral mega prostheses are required to deal with metaphyseal bone loss. Good results have been reported in small series, however, complications, including infection remain concerning, and these implants are incredibly expensive. Although performing a mega prosthesis in the setting of a well fixed TKA is not unreasonable due to immediate full weight bearing, in my opinion, prosthetic replacement should be limited to cases of failed ORIF (rare), or in cases where fixation is likely to fail (i.e., severe osteolysis distally). For the majority of fractures above well fixed components, internal fixation is preferred for the main reason that the overwhelming majority of these fractures will heal. Fixation options include retrograde nailing or lateral locked plating. Nails are typically considered in arthroplasties that allow intercondylar access (“open box PS” or CR implants) and have sufficient length of the distal fragment to allow multiple locking screws to be used. This situation is rare, as most distal fragments are quite short. If a nail is chosen, use of a long nail is preferred, since it allows the additional fixation and alignment that diaphyseal fill affords. Short nails should be discouraged since they can “toggle” in the meta-diaphysis and do not engage the diaphysis to improve coronal alignment. Plates can be used with any implant type and any length of distal fragment. The challenge with either fixation strategy is obtaining stable fixation of the distal fragment while maintaining length, alignment, and rotation. Fixation opportunities in the distal fragment can be limited due to obstacles caused by femoral component lugs, boxes, stems, cement mantles, and areas of stress shielding or osteolysis. Modern lateral locked plates can be inserted in a biologically friendly submuscular extra-periosteal fashion. More recent developments with polyaxial locked screws (that allow angulation prior to end-point locking) may offer even more versatility when distal fragment fixation is challenging. The goal of fixation is to obtain as many long locked screws in the distal fragment as possible. High union rates have been reported with modern locked plating techniques, however, biplanar fluoroscopic vigilance is required to prevent malalignments, typically valgus, distraction, and distal fragment hyperextension

Distal femur fractures (DFF) are common, especially in the elderly and high energy trauma patients. Lateral locked osteosynthesis constructs have been widely used, however non-union and implant failures are not uncommon. Recent literature advocates for the liberal use of supplemental medial plating to augment lateral locked constructs. However, there is a lack of proprietary medial plate options, with some authors supporting the use of repurposing expensive anatomic pre-contoured plates. The aim of this study was to investigate the feasibility of a readily available cost-effective medial implant option.

A retrospective analysis from January 2014 to June 2022 was performed on DFF (primary or revision) managed with supplemental medial plating with a Large Fragment Locking Compression Plate (LCP) T-Plate (~$240 AUD) via a medial sub-vastus approach. The T-plate was contoured and placed superior to the medial condyle. A combination of 4.5mm cortical, 5mm locking and/or 6.5mm cancellous screws were used, with oblique screw trajectories towards the distal lateral cortex of the lateral condyle. All extra-articular fractures and revision fixation cases were allowed to weight bear immediately. The primary outcome was union rate.

This technique was utilised on sixteen patients; 3 acute, 13 revisions; mean age 52 years (range 16-85), 81% male, 5 open fractures. The union rate was 100%, with a median time to union of 29 weeks (IQR 18-46). The mean follow-up was 15 months. There were two complications: a deep infection requiring two debridements and a prominent screw requiring removal. The mean range of motion was 1–108^o.

Supplemental medial plating of DFF with a Large Fragment LCP T-Plate is a feasible, safe, and economical option for both acute fixation and revisions. Further validation on a larger scale is warranted, along with considerations to developing a specific implant in line with these principles.

We report our early experience with the use of a non-invasive distal femoral expandable endoprosthesis in seven skeletally immature patients with osteosarcoma of the distal femur. The patients had a mean age of 12.1 years (9 to 15) at the time of surgery. The prosthesis was lengthened at appropriate intervals in outpatient clinics, without anaesthesia, using the principle of electromagnetic induction. The patients were functionally evaluated using the Musculoskeletal Tumour Society scoring system. The mean follow-up was 20.2 months (14 to 30). The prostheses were lengthened by a mean of 25 mm (4.25 to 55) and maintained a mean knee flexion of 110° (100° to 120°). The mean Musculoskeletal Tumour Society score was 68% (11 to 29). Complications developed in two patients; one developed a flexion deformity of 25° at the knee joint, which was subsequently overcome and one died of disseminated disease. The early results from patients treated with this device have been encouraging. The implant avoids multiple surgical procedures, general anaesthesia and assists in maintaining leg-length equality

Introduction: Majority of children with cerebral palsy patients suffer from fixed flexion contractures of their knees. Procedures commonly used to correct knee flexion deformities include hamstring release, anterior femoral hemiepiphyseodesis and femoral extension osteotomies. The latter procedure can cause neurovascular complications. Femoral stapling procedures are not very popular because of a theoretical risk of permanent physeal closure. We present our initial experience in correction of knee flexion deformity by using the 8-plate technique. This uses guided growth in the distal femoral physis to achieve gradual correction of the knee flexion deformity. Materials and Methods: We analysed the case notes of patients who underwent an anterior distal femoral hemi-epiphyseodesis using the 8-plate techinique between April of 2005 and August 2006. A total of 18 limbs in 12 patients underwent this procedure. Preoperative and post operative flexion deformity was measured using a goniometer. All measurements were made by the senior surgeon. Results: The mean age of the patients was 12.8 years (range between 9–16). Mean follow up time for the patients after they had undergone the procedure was 8.5 months (range 3 – 15). The Mean correction achieved – 16.15 degrees (range 5 – 40). Conclusion: We conclude that this is a simple technique with few complications to date. The learning curve for this procedure is 1 case. All patients in our series have shown promising results, with sustained gradual correction to date. We also present technical tips in the 8-plate anterior femoral hemi-epiphyseodesis procedure

Purpose. The aim of this study was to compare the accuracy of limb alignment and component positioning after total knee arthroplasty(TKA) performed using fixed or individual distal femoral valgus correction angle(VCA)in valgus knees. Materials and Methods. One hundred and twenty-four patients were randomised to undergo TKA with either of the clinical baseline, radiological outcomes and subsequent outcome such as knee HSS scores, knee range of motion (ROM) and visual analogue scale (VAS) scores were assessed. Knees in the individual group (n=62) were performed with a tailored VCA. Knees in the fixed group (n=62) were performed utilizing a 4°VCA. Results. The distribution of distal femoral valgus cut angle used in the individual group range from 3° to 8°. There were statistically significant differences between groups in post-operative hip-knee-ankle angle (individual: 180.0°±3.8°; fixed: 178.5°±2.9°; P=0.00). 86.9% of patients in the individual group had a post-operative mechanical axis deviation within ± 3°compared to 70.7% in the fixed group (P = 0.03). Patients in the fixed group had a higher percentage of postoperative residual deformity than in the individual group, and this difference was statistically significant (p=0.03). No significant differences were observed between the groups in terms of femoral and component alignment except coronal femoral component angle (α), although the size of the difference was very small(individual: 90.12°±1.61°; fixed: 88.97°±2.50°), the difference was statistically significant (P=0.00). There were no differences in HSS scores, knee ROM, or VAS pain scores in the early phase after surgery between groups. Conclusions. This study demonstrated that the VCA in patients with knee valgus deformities are smaller than normal or varus knee. Individual VCA for distal femoral resection could enhance the accuracy of postoperative neutral limb alignment in the coronal plane. Both individual and fixed VCA place the components with the similar accuracy

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

Purpose: This study examines the structural performance of different devices for the fixation of supracondylar femoral ‘T’-type intra-articular fractures. Methods: A finite element model was developed to examine three commonly used devices for fixation of ‘T’-type unstable fractures of the distal femur:-. a retrograde distal femoral nail with condylar bolts and multi-planar locking screws,. a retrograde nail with two parallel distal screws, and. a dynamic condylar screw and plate construct. The distal femoral geometry was been taken from the BEL repository. The bone was aligned with the mechanical axis and a compressive load of 2000N and separately a torsion load of 10Nm were applied. A fracture was introduced by removing a transverse 15mm slice of material and a saggital slice of 1mm thickness. The FE model examined whether any of the constructs was markedly stiffer than any other. Results: Both intra-medullary nail constructs were stiffer than the DCS, with the nail with condylar bolts and multi-planar screws being stiffer than the nail with only two parallel distal locking screws. The nail with condylar bolts did, however, produce significant levels of stress within the bone before any axial load was applied – particularly in the region adjacent to the end washers. Under torsion, the nail constructs were always more effective than the side plate construct. Conclusions: This FE model demonstrates that fixation of supracondylar femoral ‘T’-type fractures is mechanically superior with retrograde nails rather than DCS constructs. Fixation with a retrograde nail with condylar bolts plus multiplanar screws gives the stiffest fixation. High stresses are seen around the condylar bolts, but if the bone quality is adequate then the additional stiffness achieved is significant. These results support the clinical use of intra-medullary nails with compression bolts and multi-planar screws for the fixation of this type of fracture

We present the results of 15 patients revised with a Compress. ®. prosthesis secondary to failure of other distal femur reconstruction. One prosthesis had to be removed because of deep infection. Three patients needed a second surgery due to a vertical crack proximal to the anchor plug at the level of a cortical bone defect. At last follow-up, radiologic evaluation of the entire series showed a mean bone growth ratio higher than did preoperative radiographs. All patients had mainly good or excellent MSTS functional results. Distal femoral prosthetic replacement with a Compress. ®. implant in severe cases of bone loosening and instability provides a reliable reconstruction alternative that promotes bone formation. Patients with cortical defects proximal to the anchor plug should be protected with extracortical supports

We reviewed and discussed the results of thirteen distal femoral allografts in conjunction with revision total knee arthroplasty for the treatment of periprosthetic femoral supracondylar fractures associated with poor bone stock. The mean follow up time was six years. We looked at graft survivorship, functional outcome, radiographic assessment, and complications. We concluded that this is a viable salvage procedure for this type of injury. The incidence of periprosthetic supracondylar fractures of the femur is rising due to the aging population, and the increased number of total knee arthroplasties (TKA) being performed. One option for the treatment of severe fractures, associated with poor bone stock, is the use of a distal femoral allograft (DFA) in conjunction with revision TKA. The purpose of this study was to review and discuss the results of thirteen consecutive patients who were treated at our center between 1990 and 2001. Data was obtained from a prospective database. Ten of the thirteen patients were available for follow up. The average age was sixty-five years (range twenty-four to ninety-three) and the mean length of follow up was six years (range one to twelve). A chart review was performed to identify complications and graft survivorship. Functional assessment was made on the basis of the modified Hospital for Special Surgery knee score (HSS) and the MOS 36-ITEM Short Form Health Survey (SF-36). Patients were evaluated radiographically by two independent observers (kappa = 0.75, P = 0.02) in an attempt to determine union between the graft and host bone, graft resorption, and component loosening. The average postoperative HSS score and SF-36 were seventy-five and eighty-eight respectively. Mean flexion was 100°. One had an amputation due to the recurrence of infection. X-rays showed no migration, no loosening, good interface union in nine cases and mild to moderate resorption in three cases. We concluded that this is a viable salvage procedure for this type of injury

Introduction: Following resection of tumours in the distal femur, reconstruction with joint-sparing prostheses have shown good short-term functional outcomes. There is however limited literature on the affect of knee-sparing prostheses on function of the femoral physes in skeletally immature children. Method: We discuss two patients, a male (11yrs) and female (10yrs) who had joint-sparing distal femoral prostheses inserted for treatment of Ewing’s sarcoma. The knee joint, along with the distal growth plate, was preserved and fixed to the distal end of the prosthesis using unicortical screws positioned distal to the physis. In the female, these screws were removed 6 months post-op due to prominence of the screws under the skin. In both patients, we assessed radiographs from immediately post-surgery and the most recent follow-up (20 and 28 months respectively). In each set, for the operated limb, we measured the height and width of the distal femoral epiphysis, the total length of the femur and the length of the proximal femoral bone segment from the femoral head to the proximal bone-prosthesis interface. In addition, post-operative assessments of leg lengths, bilaterally, were documented. Results: In both patients, distal femoral epiphyseal height and width in the operated leg showed no significant change following endoprosthetic replacement. In the female, growth did not resume even after removal of the epiphyseal screws. In both patients, lengths of the femur and the proximal bone segment increased significantly following surgery. The patients demonstrated no clinical leg length discrepancy at the most recent follow-up. Discussion: This study suggests that the function of the distal femoral growth plate ceases following insertion of joint-sparing distal femoral endoprostheses, probably due to trans-physeal fixation. This does not appear to resume following early removal of distal screws. The proximal growth plate, however, continues to function adequately enough to maintain symmetry in overall leg length

The objective of this study was to compare the results of two consecutive series of patients with either intra-medullary uncemented stems (UCS) distal femoral endoprosthetic replacement or the Compress. ®. (CMP) distal femoral implant. Patients were divided into two groups: those who received UCS prosthesis (Group-1: 54 patients) and those who received CMP prosthesis (Group-2: 42 patients).The most frequent diagnosis was osteosarcoma. Age and gender were similar both groups. In Group-1, at a mean follow-up of 144 months, 37 prostheses were still in place. The overall Kaplan-Meier prosthetic survival rates were 79% at five and 62 % at ten years. Most of failures were long term complications. Aseptic loosening was the primary cause of late prosthetic failure. On Cox regression analysis, prosthetic stem diameter under 13mm was a significant negative prognostic factor for prosthetic survival (p=0.016). In Group-2, at a mean follow-up of 84 months, 36 prostheses were still in place. The overall rate of CMP prosthesis survival was 86% at 5 years. All complications were during the first postoperative year, being femoral fracture the main revision cause. The patients who retained the prosthesis had mainly good or excellent MSTS functional results in both groups

The use of distal femoral centralising devices has been advocated in order to achieve an even cement mantle. This has been shown to improve femoral component survival but it is recognised that the presence of voids in the mantle has a deleterious effect on the mechanical strength of cement at laboratory testing and in terms of implant survival. The effect of centralising devices on the mantle in relation to the timing of stem insertion has not previously been investigated. The purpose of this study is to assess the quality of the cement mantle in artificial bone using a polished taper stem with centralisation inserted at different stages of cement cure time and using different cements. Three cement types were studied, 45‘saw bone’ models were used. The cementation was carried out in an operating theatre at constant temperature of 23.2Ê°C. The cement was mixed according to the manufacturers instructions and pressurised. Early, intermediate and late stem insertion times were determined for each cement type. The late group included stems with and without centralisers. Video recordings of the stem cement interface were made with a 4 mm endoscope after stem removal. Large cement mantle defects were noted in the ‘with centraliser’ group in 7 out of 15 late insertion times and all had small defects in the mantle. None of the ‘without centraliser’ group had cement mantle defects. Based on our results we advise surgeons to be very aware of the timing of stem insertion when using centralisers

Purpose. The purpose of this study was to evaluate and compare the clinical, radiological outcomes of the group of patients with distal femoral cortical hypertrophy (DFCH) and without DFCH after hip arthroplasty using a cementless double tapered femoral stem and to analyze a correlation between patients factors and DFCH. Materials and Methods. Four hundreds four patients (437 hips) who underwent total hip arthroplasty (n = 293) or hemiarthroplasty (n = 144) using a Accolade TMZF femoral stem between Jun 2006 and March 2012 and were follow up period more than 24 months after surgery were enrolled in this study. They were divided into 2 groups, the one group (n = 27) included patients with DFCH, and the other group (n = 410) included patients without DFCH. The mean follow up period was 54.5 months (range, 24 to 85 months) and 56.2 months (range, 24 to 92 months) for patients with DFCH and without DFCH. Results. The mean HHS, VAS signiï¬cantly improved from 61.4 and 5.5 preoperatively to 95.9 and 1.0 at the ï¬nal follow-up, respectively (P< .001), in the DFCH group and from 57.8 and 4.5 to 91.6 and 0.6 respectively (P< .001), in the control group. There were no signiï¬cant differences between the 2 groups (P> .05). Incidence of the thigh pain in the DFCH group (18.5%) was significantly higher than the control group (2.2%) (P< .001). The mean canal flare index (CFI) and subsidence was 3.71 (range, 2.61 to 5.78) and 1.5 mm (range, 0.1 to 6.1mm) for the DFCH group, 3.30 (range, 1.31 to 5.61) and 3.4 mm (range, 0.33 to 14.9 mm) for the control group. There were significantly differences between 2 groups (p< .002, < .001). The DFCH was significantly correlated with thigh pain and subsidence (p= .001; OR, 11.194; CI, 3.434 to 36.498 for thigh pain, p= .001; OR, 0.080; CI, 0.032 to 0.198 for subsidence), but not with sex. The incidence of DFCH increased significantly with increasing CFI and decreasing age (P= .043; OR, 1.828; CI, 1.018 to 3.280 for CFI; P= .015; OR, 0.968; CI, 0.944 to 0.994 for age). All the femoral stems showed stable fixation and there was no osteolysis or loosening. Conclusion. The DFCH occurs in 6.2% after hip arthroplasties using a double tapered femoral stem. The DFCH group showed less incidence of vertical subsidence, more younger and larger CFI. Difficult over tight placement of femoral stem to the distal femur results on DFCH, as well as thigh pain in some cases. However, there was no influence on clinical outcomes and femoral stem instability, bony fixation

25 cases of closed fractures around the distal femoral growth plate were analysed prospectively over a one-year period. There were 22 males and 3 females. Mean age was 16 years (range 7 to 22). According to the classification of Salter and Harris there were 6 cases (24%) of type 1 fracture, 12 (48%) type 2 fractures, 3 (12%) type 3, and 4 (16%) type 4. Mechanism of injury was football in 13 (59%), simple fall in 4 (18%), crush in 2 (9%), RTA in 2 (9%), and fall from height in 1 (5%); in 3, the mechanism was not recorded. The average time from injury to hospital admission was 5 days (range 0 to 17 days). Management was conservative in 4 and operative in 21. The medial parapatellar approach was used in 16. Post-surgically plaster cylinders were used for a mean of 3 weeks (range 0 to 6 weeks). No patient received physiotherapy. In the operative cases, sepsis was observed in 1 case (5%). This was a crash injury with a skin ulcer that became septic postoperatively and later required knee fusion. Of the remaining 20 operative cases, 17 cases were reviewed, 4 to one year, 9 to six months, and 4 to three months. There were no cases of deformity, nor wound complications. Those reviewed at one year had an excellent range of movement averaging 0 to 117 degrees (range 0–100 to 0–140). At six months the average range of movement was 1–98 degrees (range 5–70 to 0–140) and at three months 2–62 degrees (range 10–50 to 0–95). In conclusion, we believe that these difficult fractures should usually be managed operatively where expertise allows. Preliminary results suggest that the medial parapatellar approach provides excellent access but may inhibit initial rehabilitation

Purpose. To promote rapid bone healing, an adequate stable fixation implant with a percutaneous reduction instrument should be used for Vancouver type B1 or C fractures. The objective of this study was to describe radiographic and clinical outcomes of patients with periprosthetic fracture (PPF) around a stable femoral stem, treated with a distal femoral locking plate alone or with a cerclage cable. Materials and Methods. A total of 21 patients with PPF amenable to either a reverse distal femoral locking plate (LCP DF. ®. ) alone or with a cerclage cable, with a mean age of 75.7 years, were included. In these patients, 10 fractures were treated with a reverse LCP DF. ®. alone and were classified as group I, and 11 additionally received a cerclage cable and were classified as group II.[Fig.1]. Results. Group I was not inferior to group II, as reflected by HHS evaluations. Additionally, group II had a significantly longer operation time (P = 0.019) than group I and included one patient with nonunion at the final 24-month follow-up visit after the initial fracture reduction.[Fig. 2]. Conclusion. Use of reverse LCP DF. ®. alone appears to provide advantages in the biological healing process compared with the use of reverse LCP DF. ®. with a cerclage cable. When comparing the stability of the fractures in both groups, there was no statistically significant difference, which might be attributed to the stable fixed-angle implant. For figures/tables, please contact authors directly.

Purpose. To evaluate the normal bony profiles of the anterior surface of the distal femoral cortex, its relation to the posterior condylar plane and assess the implications of these findings to anterior femoral referencing. Methods and Results. Fifty well preserved adult, cadaveric femora were studied. Different points on the proximal and distal femur were recorded using an optoelectronic system based around a commercial navigation system. Definitions were: anterior femoral plane (AFP) derived from nine points on the anterior cortex of the distal femur; posterior condylar plane (PCP) as the plane parallel to the sagittal mechanical axis of the femur and containing the PCA. The anterior femoral cortex was divided into lateral, median and medial areas. Average heights of each of these areas from the PCP were calculated, as were the angles between the PCP and AFP. Four distinct anterior cortex profiles were seen. In 28 specimens the lateral side had the highest mean height and the medial side had the lowest mean height (Group 1). For 13 specimens the lowest mean height was in the median area (Group 2) but 7 specimens had highest mean height here (Group 3). Only 2 specimens had the highest mean height on the medial side with the lowest mean height on the lateral side (Group 4). The average angle between the AFP and the PCP was 1.3° of external rotation. In Group 1 the AFP angle was more internally rotated (-10° to -2°) compared to the other groups, in particular Group 4 which showed the most external rotation (3° and 4°). Conclusions. Anterior referencing in TKA needs to represent the actual anterior shape of the distal femur cortex to prevent femur notching, femoro-patellar overstuffing or flexion gap mismanagement