BackgroundMost TKA prostheses are designed based on the anatomy of white patients. Individual studies have identified key anthropometric differences between the knees of the white population and other major ethnic groups, yet there is limited understanding of what these findings may indicate if analyzed collectively.Question/purposeWhat are the differences in morphologic features of the distal femur and proximal tibia among and within various ethnicities?MethodsA systematic review of the PubMed database and a hand-search of article bibliographies identified 235 potentially eligible English-language studies. Studies were excluded if they did not include morphology results or had insufficient data for analysis, were unrelated to the distal femur or proximal tibia, were conducted in pediatric patients or those undergoing unicondylar knee arthroplasty, or bone surface measurements were obtained for trauma products. This left 30 eligible studies (9050 knees). Study quality was assessed and reported as good, fair, or poor according to the NIH Quality Assessment Tool for Observational Cohort and Cross-Sectional Studies. Morphometric data for the distal femur and proximal tibia were available for four ethnic groups: East Asian (23 studies; 5543 knees), white (11 studies; 3111 knees), Indian (three studies; 283 knees), and black (three studies; 113 knees). Although relatively underrepresented, the knees from the Indian and black studies were maintained for hypothesis-generating purposes and to highlight crucial gaps in the data. The two key dimensions for selecting a suitable implant based on a patient’s unique anatomy—AP length and mediolateral (ML) width—were assessed for the femur and tibia, in addition to aspect ratio, calculated by dividing the ML width by the AP length. Study measurement techniques were compared visually when possible to ensure that each pooled study conducted a similar measurement process. Any significant measurement outliers were reviewed for eligibility to determine if the measurement techniques and landmarks used were comparable to the other studies included.ResultsWhite patients had larger femoral AP measurements than East Asians (62 mm, [95% CI, 57–66 mm] vs 59 mm, [95% CI, 54–63 mm]; mean difference, 3 mm; p < 0.001), a smaller femoral aspect ratio than East Asians (1.20, [95% CI, 1.11–1.29] vs 1.25, [95% CI, 1.16–1.34]; mean difference, 0.05; p = 0.001), and a larger tibial aspect ratio than black patients (1.55, [95% CI, 1.40–1.71] vs 1.49, [95% CI, 1.33–1.64]; mean difference, 0.06; p = 0.005).ConclusionsThis analysis uncovered differences of size (AP height and ML width of the femur and tibia) and shape (tibial and femoral aspect ratios) among knees from white, East Asian, and black populations. Future research is needed to understand the clinical implications of these discrepancies and to provide additional data with underrepresented groups.

This study aimed to determine the correlation between the amount of maximum flexion and the clinical outcome in 207 Koreans (333 knees) undergoing total knee replacement. The association of maximum flexion with clinical outcome was evaluated one year postoperatively using three scoring systems; the American Knee Society score, Western Ontario McMaster Universities Osteoarthritis index and the Short Form-36. The mean maximum flexion decreased post-operatively at 12 months from 140.1 degrees (60 degrees to 160 degrees ) to 133.0 degrees (105 degrees to 150 degrees ). Only the social function score of the Short Form-36 correlated significantly with maximum flexion (correlation coefficient = 0.180, p = 0.039). In comparative analyses of subgroups divided by a maximum flexion of 120 degrees , we found no significant differences in any parameters except the social function score of the Short Form-36 (41.9 vs 47.3, p = 0.031). Knees with a maximum flexion of more than 135 degrees had a better functional Western Ontario McMasters Universities Osteoarthritis index score than knees with maximum flexion of 135 degrees or less (17.5 vs 14.3, p = 0.031). We found only weak correlation between the postoperative maximum flexion and the clinical parameters for pain relief, function and quality of life, even in Korean patients. Efforts to increase post-operative maximum flexion should be exercised with caution until concerns relating to high-flexion activities are sufficiently resolved.

We aimed to document the pre-operative expectations in Korean patients undergoing total knee replacement using an established survey form and to determine whether expectations were influenced by sociodemographic factors or pre-operative functional status. Expectations regarding 17 items in the Knee Replacement Expectation Survey form were investigated in 454 patients scheduled for total knee replacement. The levels and distribution patterns of summated expectation and of five expectation categories (relief from pain, baseline activity, high flexion activity, social activity and psychological well-being) constructed from the 17 items were assessed. Univariate analyses and multivariate logistic regression were performed to examine the associations of expectations with the sociodemographic factors and the functional status. The top three expectations were relief from pain, restoration of walking ability, and psychological well-being. Of the five expectation categories, relief from pain was ranked the highest, followed by psychological well-being, restoration of baseline activity, ability to perform high flexion activities and ability to participate in social activities. An age of < 65 years, being employed, a high Western Ontario and McMaster Universities osteoarthritis index function score and a low Short-form 36 social score were found to be significantly associated with higher overall expectations.

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We found that the differences between mechanical and anatomical TFAs depend on gender and the presence of advanced OA, but not on a history of TKA. These findings indicate that prediction of mechanical TFA based on anatomical TFA is dependent on study population characteristics. This study also shows that the presence of lateral bowing of the femur is a major cause of mechanical TFA to anatomical TFA variations associated with gender and advanced OA. To reduce the adverse effects of anatomical variations on estimations of mechanical TFA based on an anatomical TFA method, more distant proximal and distal reference points are recommended to determine anatomical TFA value on standard knee radiographs.