Short-Term Study of the Outcome of a New Instrument for All-Inside Double-Bundle Anterior Cruciate Ligament Reconstruction.

PURPOSE: The purpose of this study was to evaluate the short-term clinical results and location of the bone tunnel with a new surgical procedure for all-inside double-bundle anterior cruciate ligament (ACL) reconstruction. METHODS: The double-bundle ACL reconstruction procedure was performed in 24 patients (13 male and 11 female patients) with a mean age of 31.0 years. Anterior and posterior tibial translation using an arthrometer (KT-1000; MEDmetric, San Diego, CA) and the Lysholm score were measured before surgery and at a mean of 24.8 months (range, 13 to 45 months) postoperatively. Computed tomography scans were taken to evaluate the bone tunnel positions using 3-dimensional images with the quadrant method for the femoral tunnel and Stäubli's technique for the tibial tunnel. RESULTS: Three-dimensional computed tomography scans showed that the anteromedial and posterolateral tunnels were placed in anatomically appropriate positions. Arthrometric measurements showed that the mean side-to-side differences were 5.3 mm (SD, 1.6 mm) preoperatively and 0.05 mm (SD, 0.7 mm) at a mean of 24.8 months postoperatively, indicating a remarkable improvement (P < .00001). The mean Lysholm score was 56.3 points (SD, 14.8 points) preoperatively and 95.5 points (SD, 3.8 points) at final follow-up and was significantly improved after the operation (P < .00001). CONCLUSIONS: The all-inside double-bundle ACL reconstruction technique used in this study resulted in the creation of tunnels in an anatomically appropriate position. Short-term clinical follow-up showed improvement in patient-reported outcomes and knee stability. This technique may provide an alternative option for all-inside ACL reconstruction. LEVEL OF EVIDENCE: Level IV, therapeutic case series.

A three-dimensional computed tomography study of distal femoral morphology in Japanese patients: gender differences and component fit.

BACKGROUND: Previous anthropometric studies have reported gender differences in distal femoral morphology. However, to date, very few studies have investigated the knee morphology of Japanese adults and possible gender differences. The purpose of this study was to examine the distal femoral morphology of Japanese patients, to characterize anatomical differences between male and female, and to evaluate the need to create gender-specific knee prostheses. MATERIAL AND METHODS: We evaluated 80 knees in 40 male and 40 female Japanese patients scheduled for total knee arthroplasty (TKA). The mediolateral (ML) and anteroposterior (AP) dimensions of the knees at different levels were measured preoperatively using three-dimensional computed tomography, and ML/AP aspect ratios were calculated. RESULTS: On the distal femoral cut surface, the mean ML widths were 74.9 mm for male and 65.1mm for female, and the mean AP lengths were 63.4mm for male and 58.9 mm for female. Such values were generally smaller compared to data from European and North American studies. In this study, the mean ML/AP aspect ratios were 1.31 for male and 1.25 for female, higher than those from non-Asian regions. The ML/AP ratios of Japanese patients were negatively correlated with distal femoral AP length. CONCLUSIONS: Japanese female had a relatively narrower femoral width for a given AP length than male. Our study suggests the utility of Japanese-specific implants and provides useful insights for manufacturers to design components of appropriate sizes and aspect ratios for Japanese TKA patients.

Three-dimensional motion analysis of the patellar component in total knee arthroplasty by the image matching method using image correlations.

In total knee arthroplasty (TKA), the patella is significantly associated with range of motion and gait performance. Currently, no highly accurate methods are available that can measure the 3D in vivo behavior of the TKA patellar component, as the component is made of x-ray-permeable ultra-high molecular weight polyethylene. Previously, we developed a computer simulation that matches CT scan and unidirectional radiographic images using image correlations, and applied it to kinematic studies of natural and TKA knees. The examination of the measurement accuracy for the patellar bone of a fresh-frozen pig knee joint yielded a root mean square error of 0.2 mm in translation and 0.2° in rotation. In this study, we recruited four patients who had a TKA and investigated 3D movements of the patellar component during squatting. We could visualize the patellar component using the position of the holes drilled for the component peg, and estimated and visualized the contact points between the patellar and femoral components. The principles and the utility of the simulation method are reported. This analytical method is useful for evaluating the pathologies and post-surgical conditions of the knee and other joints.