Three Dimensional CT-based Virtual Patellar Resection in Female Patients Undergoing Total Knee Replacement: A Comparison between Tendon and Subchondral Method

BACKGROUND: Due to its small size, variable shape, and lack of distinct anatomical landmarks, osteoarthritic knees make a precise patellar resection extremely difficult. METHODS: We performed virtual patellar resection with digital software using three dimensional computed tomography scans of knees from 49 patients who underwent primary total knee replacement at our hospital. We compared 2 commonly used resection methods, the tendon method (TM) and the subchondral method, to determine an ideal resection plane with respect to the symmetry and thickness of the patellar remnant. RESULTS: The TM gave a thicker resected patella, and a less oval cut surface shape, which gives better coverage for a domed prosthesis. Both methods, however, gave a symmetric resection both superior-inferiorly, as well as mediolaterally. CONCLUSIONS: Although TM appears statistically better with respect to the thickness and cut surface shape, only further intraoperative studies with long-term clinical follow-up may provide us with the most appropriate patellar resection method.

Optimal Pelvic Inlet and Outlet Radiograph Angles in Korean Patients / 대한정형외과학회잡지

PURPOSE: Until now, pelvic injuries have been evaluated with 45degrees inlet and 45degrees outlet radiographs. Following these customary guidelines may not produce the best plane to evaluate pelvic injury due to variability of pelvic anatomy. Recent data based on the American population suggested 25degrees and 60degrees as the optimal angle for each inlet and outlet views, respectively. We hypothesized that inlet and outlet radiographic views to examine the clinically relevant landmarks vary from routine 45degrees inlet and outlet views and aimed to find optimal angles for Korean patients. MATERIALS AND METHODS: One hundred consecutive patients, aged between 30 to 60 years (50 male and 50 female patients), without pelvic ring disruption or fractures who had undergone routine axial pelvic computed tomography scans were retrospectively identified. The optimal inlet and outlet angles required to profile the clinically relevant pelvic anatomy were quantified for each patient. RESULTS: The optimal inlet angle to profile the anterior body of S1 and S2 required an average caudal tilt of 24.2degrees and 27.9degrees, respectively. The average outlet angle perpendicular to the body of S1 was 54.8degrees and perpendicular to S2 was 52.3degrees. The optimal angles were the same for male and female patients and were independent of patient age. CONCLUSION: Screening inlet and screening outlet radiographs made at 25degrees and 55degrees, respectively, are recommended for viewing clinically relevant osseous pelvic anatomy in Koreans.