Influence of the Rotational Alignment of the Femoral and Patellar Components on Patellar Tilt in Total Knee Arthroplasty

PURPOSE: The purpose of this study was to analyze the influence of rotational alignment of the femoral and patellar components on patellar tilt after total knee arthroplasty (TKA). MATERIALS AND METHODS: A total of 56 patients (76 knees) who underwent TKA using Advance Medial Pivot Knee system between May 2009 and April 2011 and were available for minimum 1-year follow-up were enrolled in this study. Whiteside's line and the transepicondylar line were used to determine the rotational alignment of the femoral component. Patella cut was aimed to be parallel to the anterior patellar cortex during surgery. Radiographic evaluation was performed using plain axial radiographs. The rotational alignment of the femoral component was measured as the angle between the anterior condylar axis and the surgical transepicondylar axis. The patellar resection angle was measured between the patellar resection axis and the anterior cortical line of the patella. Patellar tilt was evaluated to investigate the correlation with the rotation of the femoral component and patellar resection angle. RESULTS: The mean rotation of the femoral component was 0.42degrees+/-3.18degrees of internal rotation. The mean patellar resection angle was 1.82degrees+/-3.44degrees, indicating medial overresection. The mean patellar tilt was 6.12degrees+/-4.31degrees of lateral tilt. The rotational angle of the femoral component showed a negative correlation with patellar tilt in the linear regression analysis (p=0.749), but the patellar resection angle showed a positive correlation with patellar tilt (p<0.001). CONCLUSIONS: Accurate patellar resection is recommended for proper patellar tracking in TKA.

Persistency and Change of the Bone Mineral Density with Alendronate Treatment after Hip Fracture

PURPOSE: The purpose of this study was to evaluate the effects of alendronate on bone mineral density (BMD) and to determine the persistency and side effects of alendronate treatment after hip fractures. MATERIALS AND METHODS: 452 patients who underwent surgery for hip fractures from March 2000 to February 2007 were retrospectively included. The hip fractures consisted of 218 cases of femur neck fractures and 234 cases of intertrochanteric fractures. There were 254 women and 198 men with a mean age of 73.4 years (range: 60~95 years) at the time of surgery. The BMD was assessed in 398 patients and 348 were diagnosed with osteoporosis, while 102 received alendronate for treatment. The persistency with alendronate treatment and change of the BMD were evaluated annually. We also evaluated the side effects and reasons for discontinuation. RESULTS: The prescription rate of alendronate was 29.3% and the persistency rate over 1 year was 33%. The annual BMD of the lumbar spine showed a 9.11% increase the first year, a 4.5% increase the second year and a 3.5% increase the third year, while negative changes were noted in the proximal femur as a 1.89% decrease the first year, a 1.38% decrease the second year and a 0.97% decrease the third year. The BMD changes were 11%(L: Lumbar spine) and 1.1%(F: Femur) for the T-scores -3.0, respectively. The BMD changes in the patients with femur neck fractures and who were treated with hemiarthroplasty were 15.6%(L) and -3.9%(F). The BMD changes in the patients with intertrochanteric hip fractures and who were treated with compression hip screws or hemiarthroplasty were 18.7%(L), 0.77%(F), 24.2%(L) and 1.19%(F), respectively. Gastrointestinal problems(19.1%) were the most common cause for discontinuation of alendronate. CONCLUSION: It is important for doctors to approach osteoporosis more carefully and educate patients to follow the prescriptions in order to improve the low prescription and persistency rates for the management of osteoporotic hip fractures. Administration of alendronate may have a positive influence on the BMD of the proximal femur by lowering the rate of decreased BMD more than would be expected.