Temporal patterns of commonly used clinical outcome scales during a 5-year period after total knee arthroplasty.

BACKGROUND: It is not established beyond doubt whether improvements in functional outcome after total knee arthroplasty (TKA) are maintained in the long term. We therefore investigated the temporal patterns of functional outcome [using range of motion (ROM), American Knee Society (AKS) score, Western Ontario and McMaster Universities Arthritis Index (WOMAC) score, and 36-Item Short Form Health Survey (SF-36) score] over a 5-year period after uncomplicated TKA, and whether these patterns differed by implant type and patient age. MATERIALS AND METHODS: This prospective study evaluated 138 patients who underwent unilateral TKA with either a mobile-bearing (MB) or fixed-bearing (FB) posterior-stabilized prosthesis. An independent investigator evaluated the functional outcome at five time points: preoperatively and at 6-month, 1-year, 2-year, and 5-year follow-up. Differences in functional outcomes between adjacent time points were evaluated by mixed-effect model repeat measurement (MMRM). RESULTS: The different functional outcome scores showed improvement till 6 months-2 years, followed by a variable decline. In patients aged ≥ 68 years with an MB implant, most of the functional outcome scores declined between 2 and 5 years after variable initial improvement till 6 months-2 years, whereas the parameters plateaued after 2 years in those aged < 68 years and in older patients with an FB implant. CONCLUSIONS: A decline in function and pain relief occurs 2 years after TKA. This decline is more evident in older patients with an MB prosthesis. Based on these findings, we believe that use of MB implants in older patients (≥ 68 years) requires further investigation. LEVEL OF EVIDENCE: Level 3.

Early Clinical Outcomes of a New Posteriorly Stabilized Total Knee Arthroplasty Prosthesis: Comparisons with Two Established Prostheses.

Purpose: We sought to determine whether early clinical performance of new posterior stabilized (PS) knee system, the Vega-PS (Aesculap), is better than that of two established total knee arthroplasty (TKA) prostheses, the E.motion-PS (Aesculap) and the Genesis II (Smith & Nephew) in terms of functional outcomes, patient satisfaction, and incidence of adverse events. Materials and Methods: We compared the clinical outcomes of 206 consecutive TKAs using Vega-PS with those of 205 TKAs using E.motion-PS and 216 TKAs using Genesis II at 2 years of follow-up. Results: Overall, the knees with the Vega-PS had better functional outcome scores than the knees with the E.motion-PS, but had similar outcome scores to the knees with the Genesis II, as evident from the American Knee Society knee score (94.2 vs. 92.5 vs. 93.2), Western Ontario McMaster Universities Osteoarthritis (WOMAC) stiffness index (1.8 vs. 2.3 vs. 2.0), WOMAC function index (11.8 vs. 16.8 vs. 18.5), Short Form 36 (SF-36) physical component summary score (41.9 vs. 39.3 vs. 41.6), and SF-36 mental component summary score (50.0 vs. 45.8 vs. 46.9). Patient satisfaction was higher in the Vega-PS and Genesis II groups than the E.motion-PS group. No notable group differences were found in terms of the incidence of adverse events. Conclusions: The Vega-PS, a newly developed PS fixed bearing prosthesis, had comparable or superior clinical performance in comparison with the two established fixed or mobile bearing PS prostheses.

Crosscultural Adaptation and Validation of the Korean Version of the New Knee Society Knee Scoring System.

BACKGROUND: The 2011 Knee Society Score© (2011 KS Score©) is used to characterize the expectations, symptoms, physical activity, and satisfaction of patients who undergo TKA and is widely used to assess the outcome of TKA. However, it has not been adapted or validated for use in Korea. QUESTIONS/PURPOSES: We developed a Korean version of the 2011 KS Score and evaluated the (1) test-retest reliability, (2) convergent validity, and (3) responsiveness of the Korean version. METHODS: The Korean version of the 2011 KS Score was derived by using a well-established translational procedure based on international guidelines, which include translation, synthesis, back-translation, expert committee review, pretesting, and submission for appraisal. A total of 123 patients with knee osteoarthritis who were scheduled to undergo TKA were recruited for the study. Ninety percent of the patients (111 of 123) were women, which is an exact representation of the Korean population having TKAs. To evaluate reliability, the patients were evaluated twice during a 4-week interval using the questionnaire. Reliability was assessed by using intraclass correlation coefficients (ICCs) and internal consistency by using Cronbach's alpha to determine the validity of the Korean version of the 2011 KS Score. The patients were evaluated by using the validated Korean versions of the WOMAC and SF-36 questionnaires. Spearman's correlation coefficient was used for validation. Responsiveness was determined by calculating the standardized response mean from the preoperative and postoperative test scores in the Korean version of the 2011 KS Score. To address the gender disparity in our study we identified 53 males who underwent TKA for osteoarthritis after completion of this study and generated age-matched controlled groups to evaluate construct validity and responsiveness in Korean males. RESULTS: The reliability proved good to excellent with an ICC between 0.69 and 0.85, depending on the clinical properties tested, which included the following: symptoms, satisfaction, expectation, and total functional activity consisting of functional activity, standard activity, advanced activity, and discretionary activity. All subscales showed good to excellent internal consistency indicated by Chronbach's alpha (range, 0.83-0.92). For validity, three of the four domains (the exception was expectation) of the 2011 KS Score, correlated either strongly or moderately with the Korean WOMAC score (r ≥ 0.35). When compared with the SF-36, the satisfaction domain showed a weak positive correlation with all the subscales of the SF-36 except general health (r < 0.35). The activity domain showed a strong positive correlation with physical function (r = 0.62) and physical component summary (r = 0.52), moderate with physical role (r = 0.46), and weak with bodily pain (r = 0.26) and social function (r = 0.31). The symptom domain also exhibited a similar moderate positive correlation with physical function (r = 0.41) and weak positive correlation with bodily pain, social function, and physical component summary (r = 0.22, 0.20, and 0.26, respectively). For responsiveness, all the domains of Korean version of the 2011 KS Score, except for expectation, showed large changes (> 0.8), calculated as standardized response mean. The total amount of the Korean version of the 2011 KS Score (2.03, p < 0.001) showed higher responsiveness when compared with the WOMAC total (1.88, p < 0.001) and SF-36 physical and mental component summaries (1.14, p < 0.001; and 0.68, p < 0.001, respectively). CONCLUSIONS: The Korean version of the 2011 KS Score was successfully developed using a process of crosscultural adaptation for the Korean-speaking population who had undergone TKA for osteoarthritis of the knee. The Korean version of the 2011 KS Score was shown to be a reliable, valid, and responsive tool and can be used to assess functional outcomes and expectations of Korean patients who undergo TKA. The demographic features of TKA in the Korean population should be taken into account with additional studies recommended to further investigate these psychometric properties in Korean men. LEVEL OF EVIDENCE: Level II, diagnostic study.

Active Flexion in Weight Bearing Better Correlates with Functional Outcomes of Total Knee Arthroplasty than Passive Flexion.

PURPOSE: Correlations between maximum flexion and functional outcomes in total knee arthroplasty (TKA) patients are reportedly weak. We investigated whether there are differences between passive maximum flexion in nonweight bearing and other types of maximum flexion and whether the type of maximum flexion correlates with functional outcomes. MATERIALS AND METHODS: A total of 210 patients (359 knees) underwent preoperative evaluation and postoperative follow-up evaluations (6, 12, and 24 months) for the assessment of clinical outcomes including maximum knee flexion. Maximum flexion was measured under five conditions: passive nonweight bearing, passive weight bearing, active nonweight bearing, and active weight bearing with or without arm support. Data were analyzed for relationships between passive maximum flexion in nonweight bearing by Pearson correlation analyses, and a variance comparison between measurement techniques via paired t test. RESULTS: We observed substantial differences between passive maximum flexion in nonweight bearing and the other four maximum flexion types. At all time points, passive maximum flexion in nonweight bearing correlated poorly with active maximum flexion in weight bearing with or without arm support. Active maximum flexion in weight bearing better correlated with functional outcomes than the other maximum flexion types. CONCLUSIONS: Our study suggests active maximum flexion in weight bearing should be reported together with passive maximum flexion in nonweight bearing in research on the knee motion arc after TKA.

Can Serum Albumin Level and Total Lymphocyte Count be Surrogates for Malnutrition to Predict Wound Complications After Total Knee Arthroplasty?

BACKGROUND: Although the serum albumin level and total lymphocyte count (TLC) have been reported as valid and reliable markers for defining malnutrition, their cutoff levels and predictive values for wound complications in patients undergoing total knee arthroplasty (TKA) remain questionable. METHODS: A total of 3169 TKAs performed between April 2003 and December 2013 were retrospectively reviewed. We determined the prevalence of malnutrition on applying different definitions, with various cutoff values of serum albumin and TLC and analyzed the variations in outcome. The differences between groups with and without malnutrition in terms of functional outcome and complications were determined using Student's t test and analysis of variance. Multivariate logistic regression analysis was conducted to identify the independent risk factors. RESULTS: Among all the patients (N = 3169), the serum albumin level and TLC varied widely, with means of 4.1 g/dL and 2189 cells/mm(3), respectively. The prevalence of malnutrition (21%) as per the conventional definition (serum albumin level <3.5 g/dL or a serum TLC <1500 cells/mm(3)) dropped to only 1.6% when malnutrition was defined as serum albumin <3.5 g/dL "and" TLC <1500/mm(3), indicating a very small overlap between the 2 markers. No differences were observed between 2 groups in functional outcomes and incidence of wound complications. CONCLUSION: Our findings call into question the values of serum albumin level and TLC as a surrogate of malnutrition for predicting wound complications after TKA.

Analysis of Longitudinal Outcome Data with Missing Values in Total Knee Arthroplasty.

We sought to determine the influence of missing data on the statistical results, and to determine which statistical method is most appropriate for the analysis of longitudinal outcome data of TKA with missing values among repeated measures ANOVA, generalized estimating equation (GEE) and mixed effects model repeated measures (MMRM). Data sets with missing values were generated with different proportion of missing data, sample size and missing-data generation mechanism. Each data set was analyzed with three statistical methods. The influence of missing data was greater with higher proportion of missing data and smaller sample size. MMRM tended to show least changes in the statistics. When missing values were generated by 'missing not at random' mechanism, no statistical methods could fully avoid deviations in the results.

Why Patients Do Not Participate in Sports Activities After Total Knee Arthroplasty.

BACKGROUND: It is important to identify the reasons or factors preventing patients from participating in sports activities after total knee arthroplasty (TKA) to improve patient satisfaction and general health that can be gained from regular sports activities. PURPOSE: To determine the reasons for lack of participation in regular sports activities after TKA as perceived by patients and to identify specific factors involved. STUDY DESIGN: Case series; Level of evidence, 4. METHODS: A total of 369 patients with a follow-up longer than 1 year after TKA were included in this retrospective study. A postal survey regarding sports activities was conducted using a questionnaire gathering information such as sociodemographic data, activity levels, and sports activities after TKA. The reasons perceived by patients for not participating in sports activities were determined. Patients unable to participate in sports activities were compared with patients able to do so in terms of sociodemographic data and pre- and postoperative outcomes. RESULTS: Of the 369 patients, 88 (24%) replied that they could not participate in a sports activity. Among the perceived reasons, reasons not related to the replaced knee were more frequent than those related to the replaced knee (76% vs 24%). Symptoms related to the spine or other joints composed 25% of the total perceived reasons. The presence of medical comorbidities accounted for 16%, while symptoms in the nonreplaced knee represented 8% of the reasons. In terms of patient factors, multivariate logistic regression revealed that male sex, a floor-based (ie, non-Western) lifestyle with greater demands on knee flexion, and worse postoperative University of California at Los Angeles activity scale were associated with nonregular sports activity levels. CONCLUSION: The perceived reasons and patient factors hindering regular sports activities after TKA were not restricted to problems with the replaced knee. Nonetheless, orthopaedic surgeons may have a substantial role in encouraging patients to participate in sports by resolving joint-related problems. Furthermore, this study supports the notion that a multidisciplinary approach is needed to improve sports participation after surgery.

Functional Outcomes of a New Mobile-Bearing Ultra-Congruent TKA System: Comparison With the Posterior Stabilized System.

We determined whether a new mobile-bearing ultra-congruent (UC) TKA system provides better functional outcomes than an established posterior-stabilized (PS) prosthesis. The functional outcomes (motion arc, AKS scores, WOMAC Index, and SForm-36 scores evaluated at 1 and 2 years postoperatively), satisfaction and incidences of adverse events were compared between the knees implanted with mobile-bearing UC prosthesis (n=103) and the mobile-bearing PS prosthesis (n=99). At 2 years, mobile-bearing UC TKAs showed similar functional outcomes and satisfaction, but smaller motion arc compared to mobile-bearing PS TKAs (126° vs. 131°). There were no differences in the incidence of adverse events. Mobile-bearing UC prosthesis can be considered a safe and viable alternative to the PS design, with an expectation of smaller postoperative maximum flexion.

Clinical Implications of Femoral Anthropometrical Features for Total Knee Arthroplasty in Koreans.

Anthropometric features of Asians femora and their clinical relevance with regard to TKA are not rigorously investigated. We attempted to determine how well current prostheses accommodate femoral anthropometric features of Koreans and whether the presence of condylar or trochlear overhang or underhang adversely affects functional outcomes. We hypothesized that current prostheses do not accommodate Korean female femora well, and that overhang or underhang would adversely affect outcomes. Condylar and trochlear mediolateral (ML) widths and condylar anteroposterior (AP) heights were measured, and ML/AP ratios were calculated in 1025 osteoarthritic knees that underwent TKA. Besides gender difference, wide individual variation exists in condylar and trochlear widths and ML/AP aspect ratios for given AP heights. Size options of current prostheses could not cover the wide ranges of ML widths for given AP heights. The knees with condylar overhang more than 4mm showed lower maximum flexion angle postoperatively (P=0.005).

Patients still wish for key improvements after total knee arthroplasty.

PURPOSE: Our goals were to rigorously document and explore the interrelationships of various parameters in the aftermath of total knee arthroplasty (TKA), including patient characteristics, clinical scores, satisfaction levels, and patient-perceived improvements. MATERIALS AND METHODS: A questionnaire addressing sociodemographic factors, levels of satisfaction, and "wished-for" improvements was administered to 180 patients at least 1 year post primary TKA. Both satisfaction levels and wished-for improvements were assessed through nine paired parameters. Patients responded using an 11-point visual analogue scale (VAS) and the results were summarized as mean VAS score. Correlations between clinical scores and satisfaction levels and between satisfaction levels and desired improvements were analyzed. RESULTS: Patient satisfaction levels were only modest (mean score, 4-7) for eight of the nine parameters, including pain relief and restoration of daily living activities, the top two ranked parameters in wished-for improvement while high-flexion activity constituted the top source of discontent. Wished-for improvement was high in seven parameters, the top three being restoration of daily living activities, pain relief, and high-flexion activity. The effects of sociodemographic factors on satisfaction levels and wished-for improvement varied. Satisfaction levels correlated positively with functional outcomes, and satisfaction in pain relief and restoration of daily living activities correlated more often and most strongly with clinical scores. CONCLUSIONS: Following TKA, patient satisfaction is not high for a number of issues, with improvements clearly needed in restoring daily living activities and relieving pain. Continued efforts to achieve better surgical outcomes should address patient-perceived shortcomings.

Prevalence of osteoporosis in female patients with advanced knee osteoarthritis undergoing total knee arthroplasty.

This study sought to demonstrate bone mineral density (BMD) conditions in elderly female patients with knee osteoarthritis (OA) undergoing total knee arthroplasty (TKA). In addition, we sought to determine whether their BMD conditions differ from those of community-based females without knee OA. Finally we sought to determine whether clinical statuses are related to BMD in the knee OA patients. BMD conditions in 347 female patients undergoing TKA and 273 community-based females were evaluated. Additionally, comparative analyses of BMD between age and body mass index-matched knee OA groups (n=212) and the control groups (n=212) were performed. In the pre-matched knee OA group, regression analyses were performed to determine whether preoperative clinical statuses were related to BMD. Considerable prevalence of coexistent osteoporosis (31%) was found in the pre-matched knee OA patients undergoing TKA. We found no significant differences of the BMD T-scores and the prevalence of osteoporosis between the age and body mass index-matched knee OA and control groups. In the pre-matched knee OA patients, poorer preoperative clinical scores were related to poorer BMD T-scores in the proximal femur and/or lumbar spine. Our study suggests that more attention should be paid to identify and treat osteoporosis in elderly female patients with advanced knee OA undergoing TKA.

Prevalence and predictors of post-operative coronal alignment outliers and their association with the functional outcomes in navigated total knee arthroplasty.

We aimed to determine the prevalence and predictors for being an outlier after navigated TKA and asked whether navigated TKAs with perfect coronal alignment have better functional outcomes than those without it. Alignment was measured in 124 patients (191 knees) with navigated TKAs who were available for 1year functional outcome assessment. The outcomes were compared among the 3 subgroups divided by the deviation of mechanical axis from neutral (0°): the perfect, 0° or within 1°; the acceptable, 1°-3°; and the outlier, beyond 3°. The prevalence of outliers was 20.4%, and the severity of preoperative varus deformity was the strongest predictor. Accuracy of coronal alignment in radiographs did not correlate consistently with functional outcomes.

Activity levels and participation in physical activities by Korean patients following total knee arthroplasty.

BACKGROUND: The objectives of this study were to describe changes in physical activity profiles of Korean patients after TKA and to determine whether the postoperative physical activity level is influenced by patient socio-demographic factors and postoperative functional outcomes. We also sought to determine whether regular postoperative physical activity is associated with greater patient satisfaction after TKA. METHODS: This observational study included 369 patients. Physical activity profiles before and after TKA were evaluated using a questionnaire that contained the UCLA activity scale and types of sports activities. The associations of socio-demographic features and postoperative functional outcomes with the physical activity levels were assessed using subgroup comparisons and partial correlation analyses. In addition, the effects of regular physical activity on patient satisfaction with replaced knees were evaluated using subgroup comparisons. RESULTS: Walking, swimming and bicycling were the three most common sports activities both before and after TKA. After TKA, the mean activity level remained similar (UCLA score = 4.5 before TKA vs. 4.8 after TKA); however, the frequency of moderate activity levels (UCLA scale, 4-6) and moderate types of physical activities increased. Patients with higher postoperative function scores reported higher postoperative activity levels, but socio-demographic factors were not associated with activity level. Regular physical activity was associated with greater patient satisfaction. CONCLUSIONS: This study provides valuable information about realistic expectations for physical activity after TKA. Regular participation in physical activity should be encouraged to improve patient satisfaction.

Clinical value of tranexamic acid in unilateral and simultaneous bilateral TKAs under a contemporary blood-saving protocol: a randomized controlled trial.

PURPOSE: Despite the documented blood-saving effects of tranexamic acid (TNA) in total knee arthroplasty (TKA), the question whether clinical values of TNA are identical in unilateral and bilateral TKAs remains unclear. This study was undertaken to determine the clinical values of TNA in unilateral and simultaneous bilateral TKAs under a contemporary blood-saving protocol in terms of efficacy (total blood loss and transfusion rate) and safety (the incidences of symptomatic deep vein thrombosis and pulmonary embolism). METHODS: One hundred and eighty unilateral and 146 bilateral TKA patients were randomized into TNA group or control group. In unilateral TKA patients, TNA (10 mg/kg) was administered intravenously 20 min before tourniquet deflation and repeated 3 h after surgery. In bilateral TKA patients, one more dose (10 mg/kg) was given before tourniquet deflation in the second TKA. A contemporary blood-saving protocol was applied to all patients. The TNA and control groups were compared separately in unilateral and bilateral TKA patients for the efficacy and safety variables. RESULTS: In unilateral TKA patients, the TNA group had less total blood loss (905 vs. 1,018 mL, p = 0.018) than the control group, but there was no difference in the allogenic transfusion rate (1 vs. 7 %, n.s.). In bilateral TKA patients, the TNA group showed no differences in total blood loss (1,282 vs. 1,379 mL, n.s.), but a significant reduction in the allogenic transfusion rate (7 vs. 27 %, p = 0.002). No symptomatic deep vein thrombosis or pulmonary embolism was found in all patients. CONCLUSION: This study demonstrates that the use of TNA reduces total blood loss, but the effects on the transfusion rate can differ depending on the type of TKAs (unilateral vs. bilateral) and the blood-saving protocols.

Coexisting lumbar spondylosis in patients undergoing TKA: how common and how serious?

BACKGROUND: Information on the coexistence of lumbar spondylosis and its influence on overall levels of pain and function in patients with advanced knee osteoarthritis (OA) undergoing total knee arthroplasty (TKA) would be valuable for patient consultation and management. QUESTIONS/PURPOSES: The purposes of this study were to document the prevalence and severity of coexisting lumbar spondylosis in patients with advanced knee OA undergoing TKA and to determine whether the coexisting lumbar spondylosis at the time of TKA adversely affects clinical scores in affected patients before and 2 years after TKA. METHODS: Radiographic lumbar spine degeneration and lumbar spine symptoms including lower back pain, radiating pain at rest, and radiating pain with activity were assessed in 225 patients undergoing TKA. In addition, the WOMAC score and the SF-36 scores were evaluated before and 2 years after TKA. Potential associations of radiographic lumbar spine degeneration and lumbar spine symptom severities with pre- and postoperative WOMAC subscales and SF-36 scores were examined. RESULTS: All 225 patients had radiographic degeneration of the lumbar spine, and the large majority (89% [200 of 225]) had either moderate or severe spondylosis (72% and 17%, respectively). A total of 114 patients (51%) had at least one moderate or severe lumbar spine symptom. No association was found between radiographic severity of lumbar spine degeneration and pre- and postoperative clinical scores. In terms of lumbar spine symptoms, more severe symptoms were likely to adversely affect the preoperative WOMAC and SF-36 physical component summary (PCS) scores, but most of these adverse effects improved by 2 years after TKA with the exception of the association between severe radiating pain during activity and a poorer postoperative SF-36 PCS score (regression coefficient = -5.41, p = 0.015). CONCLUSIONS: Radiographic lumbar spine degeneration and lumbar spine symptoms are common among patients with advanced knee OA undergoing TKA. Severe lumbar spine symptoms (visual analog scale score of ≥ 7) were likely to adversely affect the preoperative clinical scores of patients undergoing TKA; however, most of the adverse effects were not found 2 years after TKA. Nevertheless, because preexisting severe radiating pain during activity may be a source of a poorer outcome after TKA, careful patient consultation regarding this potential poorer prognosis after TKA needs to be provided to the patient with this symptom.

The patterns of limb length, height, weight and body mass index changes after total knee arthroplasty.

The objective of this retrospective review of 466 patients was to document changes in limb length, leg length discrepancy (LLD), height, weight, and body mass index (BMI) 1 year after TKA and the patterns of height, weight, and BMI during 5 years. To determine change patterns over 5 years, the data of 291 patients were analyzed and compared with those of age and gender-matched normal subjects. Limb length, height, and weight increased, BMI remained unchanged, and LLD decreased 1 year after TKA. The bilateral group had a greater height increase and lower rate of LLD. Preoperative mechanical tibiofemoral angle was related to limb length increase, and patients with a smaller preoperative BMI showed more weight gain. During the 5 years, weight and BMI at 1 year were maintained, but height diminished, while the healthy population showed a decreasing trend in weight.

Must bilaterality be considered in statistical analyses of total knee arthroplasty?

BACKGROUND: In studies of TKA, treating each knee as an independent case in patients with bilateral TKAs can lead to errors, because patients with bilateral and unilateral TKAs may achieve different levels of function and because the assumption of statistical independence is violated. QUESTIONS/PURPOSES: We determined whether (1) patients undergoing bilateral TKAs have different demographics and preoperative and postoperative function from those undergoing unilateral TKAs, and (2) means, SEs, and p values change substantially based on how the two cases of bilateral TKAs are treated in statistical analyses. METHODS: We retrospectively compared 513 patients undergoing unilateral TKAs and 602 patients undergoing bilateral TKAs regarding demographics (age, gender, BMI), preoperative and 1-year postoperative function (motion arc, American Knee Society score, patellofemoral score, WOMAC(TM), SF-36). Each case of a bilateral TKA was treated as independent in the reference analyses. Then changes of mean, SEs, and p values were compared with those of the reference method when three other methods of analysis were used: using mean values of both knees, randomly selecting one side, and using a generalized estimating equation. RESULTS: Patients undergoing bilateral TKAs had higher female predominance (95% versus 90%) and BMI (27.4 versus 26.1 kg/m(2)) than those undergoing unilateral TKAs. Although patients undergoing bilateral TKAs had worse preoperative function, they achieved comparable function at 1 year. The mean values did not differ considerably depending on the four methods. The SEs and p values of the reference method were generally the smallest, but the differences appeared negligible. CONCLUSIONS: Our analyses suggest bilaterality can be ignored in the analysis of TKA, since postoperative function is comparable between unilateral and bilateral TKAs and the theoretical errors in statistical analysis had little effect on the results.

Femoral lateral bowing and varus condylar orientation are prevalent and affect axial alignment of TKA in Koreans.

BACKGROUND: Coronal alignment is considered key to the function and longevity of a TKA. However, most studies do not consider femoral and tibial anatomical features such as lateral femoral bowing and the effects of these features and subsequent alignment on function after TKA are unclear. QUESTIONS/PURPOSES: We therefore determined (1) the prevalence of lateral femoral bowing, varus femoral condylar orientation, and severe tibia plateau inclination in female Koreans undergoing TKA; (2) whether postoperative alignments are affected by these anatomical features and improved by the use of navigation; and (3) whether postoperative coronal alignments are associated with function. METHODS: We measured alignment in 367 knees that underwent TKA and 60 sex- and age-matched normal knees (control group). We determined patterns and degrees of femoral bowing angle, femoral condylar orientation, and tibial plateau inclination on preoperative full-limb radiographs. Postoperatively, coronal alignment of limbs and of femoral and tibial components was measured. We compared American Knee Society scores, WOMAC scores, and SF-36 scores in aligned knees and outliers (beyond ± 3° or ± 2°) at 1 year. RESULTS: The prevalence of lateral femoral bowing was 88% in the TKA group and 77% in the control group. Mean femoral condylar orientation angle was varus 2.6° in the TKA group and valgus 1.1° in the control group, and mean tibial plateau inclination was varus 8.3° in the TKA group and varus 5.4° in the control group. Femoral lateral bowing and varus femoral condylar orientation were associated with postoperative alignments. Several clinical outcome scales were inferior in the outliers in mechanical tibiofemoral angle, anatomical tibiofemoral angle, and tibial coronal alignment but not in femoral coronal alignment outliers. CONCLUSIONS: Lateral femoral bowing, varus condylar orientation, and severe varus inclination of the tibia plateau should be considered when performing TKA in Korean patients or patients with otherwise similar anatomical features.

Incidence, predictors, and effects of residual flexion contracture on clinical outcomes of total knee arthroplasty.

Patients who present with large flexion contracture (FC) but have well maintained maximum flexion tend to have a flexion-extension gap mismatch, which can cause residual FC or flexion instability after TKA. We routinely use posterior-stabilized implants, perform soft tissue balancing and additional distal femur resection, and determine the polyethylene insert thickness based on flexion-extension gap difference to avoid postoperative FC and flexion instability. We retrospectively reviewed 911 TKAs performed with this protocol to determine the incidence, predictors and effects of postoperative FC on clinical outcomes. Knees with postoperative FC ≥10° were identified, and their clinical outcomes were compared with knees without FC. The average follow-up period was 35months (range, 24-72months). Eighteen (2.0%) of the 911 knees presented with postoperative FC. The occurrence of postoperative FC was associated with preoperative FC and anterior knee pain, but not with a flexion-extension gap mismatch. A mild to moderate postoperative FC does not increase pain, but may be detrimental to quality of life.