Early Results of Total Knee Arthroplasty Using a Built-in 3-Degree External Rotation Prosthesis

PURPOSE: We compared the outcomes of total knee arthroplasty (TKA) using the Genesis II prosthesis in which 3degrees of external rotation was incorporated into the femoral component and Nexgen LPS prosthesis in which the degree of external rotation was determined by the extent of intraoperative bone cutting. MATERIALS AND METHODS: Of the patients who underwent TKA for osteoarthritis between November 2006 and December 2009, 326 patients (572 knees) were included in this study. The prosthesis of choice was Genesis II in 199 knees and Nexgen LPS in 373 knees. The mean follow-up was 27 months (range, 24 to 51 months). The American Knee Society score (KSS) and function score (FS) were used for clinical assessments. The maximum flexion angle and patellar tilt were compared between the groups. RESULTS: At the final follow-up, no significant intergroup difference was observed regarding the KSS (p=0.217), FS (p=0.238), maximum flexion angle (p=0.124), and patellar tilt (p=0.156). CONCLUSIONS: There was no significant difference in the clinical outcomes and patellar tilt between the prosthesis in which 3degrees of external rotation was incorporated into the femoral component and the prosthesis in which external rotation was determined based on bone cutting.

Prediction of Rotationally Neutral State of the Femur by Comparing with the Shape of Contra-lateral Lesser Trohanter / 대한정형외과학회잡지

PURPOSE: To evaluate the accuracy and reliability of method for prediction of rotationally neutral state of the femur by comparing with contra-lateral lesser trochanter. MATERIALS AND METHODS: The rotationally neutral state of the femur was measured by comparing the shape of the opposite side of the lesser trochanter in a normal group of 100 adult. Each examination was performed independently by three observers. The observers predicted a position presumed to be neutral by comparing the shape of lesser trochanter with that of contra-lateral side previously recorded by the C-arm image intensifier. We evaluated the mean angular discrepancy that is different from the neutral point and assessed the inter-observer variations. RESULTS: The mean angular discrepancy (SD) was 3.4 degree(+/-2.4); 3.5 degree(+/-2.4) by observer-1,3.5 degree (+/-2.8) by observer-2, 3.2 degree(+/-2.2) by observer-3. There was no inter-observer variation (p=0.87). 77% of all observers indicated below 4 degree and no one over 15 degree. CONCLUSIONS: The method of comparing the shape of both lesser trochanters is considered to be effective in determining the rotational status of the femur. It could be used as a practical method in the operation of the femoral fracture for prevention of rotational deformity intra-operatively