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.

Patient satisfaction is becoming increasingly important as a crucial outcome measure for total knee arthroplasty (TKA). We aimed to determine how well commonly-used clinical outcome scales correlate with patient satisfaction after TKA. In particular, we sought to determine whether patient satisfactions correlate better with absolute postoperative scores or preoperative to 12-month postoperative changes. Patient satisfaction was evaluated using four grades (enthusiastic, satisfied, noncommittal, and disappointed) for 438 replaced knees that were followed for longer than one year. Outcomes scales used AKS, WOMAC and SF-36 scores. Correlation analyses were performed to investigate the relation between patient satisfaction and the 2 different aspects of the outcome scales: postoperative scores evaluated at latest follow-ups and pre- to postoperative changes. The WOMAC function score was most strongly correlated with satisfaction (correlation Coefficient = 0.45). Absolute postoperative scores were better correlated with satisfaction than the pre- to postoperative changes for all scales. This study demonstrates that patient satisfaction correlates better with patient-derived and disease specific scales (WOMAC) than physician-driven (AKS) or generic (SF-36) measures. The present study also shows that absolute postoperative status is more important pre- to postoperative change when determining patient satisfaction.

Background: Previous studies reported that several kinematic parameters such as tibial posterior slope, joint line, and femoral posterior condylar offset influence clinical outcomes including maximum flexion after total knee arthroplasty (TKA). However, the effects of the kinematic factors may vary with the implant type. We aimed to determine whether implant type influence the associations between the three kinematic factors (posterior slope, joint line, posterior condylar offset) and clinical outcomes. We hypothesized that the associations between the kinematic factors and clinical outcomes would differ among four implant types [fixed bearing cruciate retaining (FB-CR), fixed bearing posterior stabilized (FB-PS), mobile bearing cruciate retaining (MB-CR), and mobile bearing posterior stabilized (MB-PS)]. Methods: A retrospective review of 1300 TKAs performed with one of the four implant types (FB-CR, FB-PS, MB-CR, MB-PS) was performed to select 50 TKAs for each implant type of which 1 year clinical outcomes (maximum flexion, AKS scores, patellofemoral scores, WOMAC, and SF-36) were available. Three radiographic parameters (posterior slope, joint line, and posterior condylar offset) were measured using pre- and post-operative lateral radiographs and postoperative alterations were calculated from the measurements. The correlations between the alterations in the radiographic parameters and the clinical outcomes were compared among the four groups by the implant type. Results: In 4 designs of implant (FB-CR, FB-PS, MB-CR and MB-PS), the mean increase in posterior condylar offset was +0.22, +0.67, +0.33 and +1.26, respectively. The mean joint elevation was −0.31, +1.34, −0.12 and +1.96, respectively. The mean posterior slope was 6.10, 5.64, 5.01 and 4.59, respectively. The mean maximum flexion was greater in the PS designs than in the CR designs (137.0° in FB-PS and 136.4° in MB-PS vs. 132.2° in MB-CR and 130.1° in FB-CR, p < 0.05). No significant correlations between the alterations in the radiographic parameters and maximum flexion. No significant correlations were found between the alterations in the radiographic parameters and the clinical outcomes in all implant types but the MB-CR type. In MB-CR type, the elevation of joint line was significantly associated with worse WOMAC stiffness and function scores (correlation Coefficient = 0.36 and 0.30, respectively) and the increase of posterior condylar offset was associated with a worse WOMAC pain score (correlation coefficient = 0.39). Conclusion: Our findings indicate that the effects of the alterations in the kinematic parameters on the clinical outcomes vary with the implant type. This study also indicates that implant type is more important in determining postoperative maximum flexion than the alterations in the kinematic parameters.

Introduction: Mobile bearing TKA systems have drawn great attention as an alternative solution for the limitations of fixed bearing designs. Recently rotating platform posterior stabilized (RP-PS) was developed to take advantage of the benefits originating from the design features of the traditional rotating platform mobile bearing system and the traditional posterior stabilized fixed bearing system with post and cam mechanism. Despite its theoretical advantages, the clinical outcomes of TKAs with RP-PS mobile bearing system remain to be determined. In theory, compared to fixed bearing systems, clinical performances of mobile bearing knees may be more sensitive to the rehabilitation status due to its relatively small constraint by the prostheses. Therefore, the clinical outcomes can be vary with the follow-up periods. This study was conducted to compare the longitudinal clinical outcomes of TKAs with a RP-PS mobile system and with a floating platform mobile bearing system. Methods: 163 TKAs with one of two mobile bearing systems (E.motion-FP and E.motion-PS: B.Braun-Aesculap, Tuttlingen, Germany) were included in this study. All surgeries were performed by a single surgeon using a computer assisted navigation system (Orthopilot, B.Braun-Aesculap). Clinical outcomes evaluated at 6 months, 12 months, and 24 months were compared between the 70 knees with E.motion-FP and the 93 knees with E.motion-PS. Radiographic measurements of limb alignment and implant positioning showed no significant differences between the two groups.

Results: Compared to TKAs with the FP prosthesis, TKAs with the RP-PS prosthesis had greater maximum flexion (128.9 vs. 135.3, p = 0.001) and tended to be more satisfactory (satisfaction level: 3.4 vs. 3.1, p = 0.052). The other clinical outcome scales (AKS knee and function, PF, WOMAC, and SF-36) showed comparable results. No failures were found in both groups. Conclusion: We found that TKAs with the RP-PS mobile bearing system have greater maximum flexion and patient satisfaction than TKAs with the FP mobile bearing system. The long term benefits 2009

Comprehensive anthropometric information is essential to avoid patella-related complications after TKA. We compared the anthropometric patellar dimensions of Korean and Western patients. In particular, we determined whether the reestablishment of original patellar thickness, residual bony thickness, and pre- to postoperative deviations between the median ridge position and the component center position influence the clinical and radiographic outcomes of TKAs. We measured anthropometric patellar dimensions in 752 osteoarthritic knees treated with TKA in 466 Korean patients and compared them with those of Western patients reported in the literature. We investigated the effects of postoperative overall thickness deviations, residual bony thickness after bone resection, and postoperative deviations of component center positions from median ridge positions versus clinical and radiographic outcomes evaluated 1 year after surgery. Korean patients undergoing TKA had thinner and smaller patellae than Western patients. We found no associations between pre- to postoperative overall thickness differences and clinical and radiographic outcomes and no differences between knees with a residual bony thickness of 12 mm or more and knees with a residual thickness of less than 12 mm, with the exception of WOMAC pain scores. We found no associations between postoperative deviations of component center position and clinical or radiographic outcomes. Our findings indicate bone resection for patellar resurfacing can be flexible without jeopardizing clinical outcome.

We examined the placement of the stem in relation to the medial tibial cortex when using total knee replacements (TKRs) with medially-offset tibial stems in Korean patients. Measurements were performed on the pre- and post-operative radiographs of 246 osteoarthritic knees replaced between January 2005 and May 2006 using the Genesis II or E-motion TKR with a medially-offset stem. Pre-operatively, we measured the distance between the mechanical axis and that of the tibial shaft and post-operatively, that between the midline of the tibial stem and the axis of the shaft.

Knees were identified in which there was radiological contact between the tip of the stem and the medial tibial cortex. The mechanical axis was located medial to the axis of the shaft in 203 knees (82.5%). Post-operatively, the midline of the tibial stem was located medial to the tibial shaft axis in 196 knees (79.7%). In 16 knees (6.5%) there was radiological contact between the tibial stem or cement mantle and the medial tibial cortex.

Our study has shown that the medially-offset stem in the tibial component may not be a good option for knees undergoing replacement for advanced osteoarthritis in some Korean patients.

We investigated the association between the radiological findings and the symptoms arising from the patellofemoral joint in advanced osteoarthritis (OA) of the knee. Four radiological features, joint space narrowing, osteophyte formation, translation of the patella and focal attrition were assessed in 151 consecutive osteoarthritic knees in 107 patients undergoing total knee replacement. The symptoms which were assessed included anterior knee pain which was scored, the ability to rise from a chair and climb stairs, and quadriceps weakness.

Among the radiological features, only patellar translation and obliteration of the joint space had a statistically significant association with anterior knee pain (odds ratio (OR) 4.85; 95% confidence interval (CI) 1.83 to 12.88 and OR 11.23; 95% CI 2.44 to 51.62) respectively. Patellar translation had a statistically significant association with difficulty in rising from a chair (OR 9.06; 95% CI 1.75 to 45.11). Other radiological features, including osteophytes, joint space narrowing, and focal attrition had no significant association.

Our study indicates that the radiological findings of patellar translation and significant loss of cartilage are predictive of patellofemoral symptoms and functional limitation in advanced OA of the knee.

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° (60° to 160°) to 133.0° (105° to 150°). 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°, 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° had a better functional Western Ontario McMasters Universities Osteoarthritis index score than knees with maximum flexion of 135° 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 sought to determine the degree of correlation between the condition of the patellar articular cartilage and patellofemoral symptoms and function in osteoarthritic patients undergoing total knee arthroplasty. The depth of the osteoarthritic lesion, as graded by the Outerbridge classification and its size and location were assessed to determine the condition of the patellar cartilage in 80 consecutive osteoarthritic knees undergoing total knee arthroplasty. The association between the condition of the cartilage and patellofemoral symptoms and function was investigated by correlation analysis.

The depth and size of the lesion had a significant but weak correlation with anterior knee pain (r = −0.300 and −0.289; p = 0.007 and 0.009, respectively), whereas location had no significant association (p > 0.05). None had a significant association with patellofemoral functional parameters (chair-rising, stair-climbing, and quadriceps power) (p > 0.05).

Our study indicates that patellofemoral symptoms and function are not completely determined by the condition of the cartilage. Caution should be taken when the symptoms and functional limitations are attributed to a lesion in the patellofemoral joint in making a decision regarding patellar resurfacing in total knee arthroplasty.