Multidirectional Tibial Tubercle Transfer Technique: Rationale and Biomechanical Investigation.

This study describes a new surgical technique to transfer the tibial tubercle, explains the rationale for its development, and reports the results of initial biomechanical testing. The design goals were to create a tibial tubercle osteotomy that would provide equivalent or better initial fixation compared with traditional techniques, yet would be more flexible, reproducible, accurate, less invasive, and safer. The results of the biomechanical analysis suggest that initial fixation with this novel tubercle transfer technique is as strong as traditional Elmslie-Trillat and anteromedialization procedures.

Utility of polymer cerclage cables in revision shoulder arthroplasty.

Revision shoulder arthroplasty often requires humeral osteotomy for stem extraction or is complicated by periprosthetic fracture. In these situations, various modes of fixation are used, including cerclage wires, cable plates, and allograft strut augmentation. The use of metal wires and cables, however, has been associated with soft tissue irritation, sharps injuries, and accelerated wear of joint arthroplasty bearing surfaces. As an alternative to traditional metal cables, the SuperCable (Kinamed Inc, Camarillo, California) contains braided ultra-high molecular-weight polyethylene fibers surrounding a nylon core. To date, no studies have examined the use of nonmetallic cerclage cables in shoulder arthroplasty.A retrospective review was performed of 11 patients who underwent shoulder arthroplasty for which nonmetallic cerclage cables were used. Clinical and radiographic data were examined regarding patient age, procedure performed, indication for cerclage cabling, time to healing of osteotomy or fracture, and any complications associated with the use of these cerclage cables. Minimum follow-up was 1 year. Ten patients underwent reverse total shoulder arthroplasty, and 1 patient underwent revision unconstrained total shoulder arthroplasty. Mean follow-up was 20.5 months. Ten patients required humeral osteotomy for stem or cement removal. Allograft augmentation was performed in 7 patients. Mean time to healing was 3.2 months. No patients experienced loosening or migration of hardware or allograft, and no complications directly related to the use of nonmetallic cerclage cables were identified.

Patellofemoral arthroplasty with a customized trochlear prosthesis.

Successful patellofemoral arthroplasty depends on appropriate patient selection, proper prosthesis design, and correct surgical technique. Clinical results using off-the-shelf patellofemoral prostheses have reported mixed results primarily because of an inability to address these important characteristics adequately. This article reviews the design rationale, excellent clinical history, and straightforward surgical technique of a unique approach to patellofemoral arthroplasty that incorporates a customized trochlear prosthesis designed to fit the individual patient's patellofemoral groove. Clinical results using this customized approach demonstrate that it is a safe and effective treatment option for patients who have isolated patellofemoral arthritis.

Safety and utility of computer-aided shoulder arthroplasty.

This study evaluated the safety and utility of a novel, image-free, shoulder navigation system in a cadaver and in an initial cohort of shoulder arthroplasty patients. Shoulder arthroplasty was performed on a cadaver and 27 patients using an image-free navigation system (NaviProtrade mark; Kinamed Navigation Systems LLC, Camarillo, CA). Optical trackers were attached to the proximal humerus and the coracoid process. Prior to and following humeral head resection, the anatomic neck axis (retroversion, inclination) and humeral head diameter were measured with the navigation system. Native glenoid surface orientation was registered, and a navigation tracker was attached to the glenoid reamer. The navigation system recorded change in inclination and version relative to the native glenoid during reaming. The cadaver results demonstrated that the trackers did not impede surgical performance and that system accuracy was 2.6 degrees +/- 2.5 degrees . In the clinical series, the navigation system reported the anatomic humeral neck measurements (retroversion 30.0 degrees +/- 16.0 degrees ; inclination 137.0 degrees +/- 11.7 degrees ), the humeral head diameters (major axis 46.2 mm +/- 4.8 mm; minor axis 43.2 mm +/- 3.8 mm), the humeral neck resection angles (retroversion 29.9 degrees +/- 15.1 degrees and inclination 135.6 degrees +/- 9.1 degrees ), and glenoid reaming orientation relative to the native glenoid (+3.0 degrees +/- 6.3 degrees of version; -6.7 degrees +/- 4.4 degrees of inclination). This initial clinical experience with computer-aided shoulder navigation demonstrates that the procedure is safe and can provide valuable intraoperative measurements. With an anatomic humeral implant system, the navigation system provides real-time feedback on the humeral resection as it relates to anatomic neck geometry. The system also provides real-time angulation of the glenoid reamer relative to preoperative glenoid deformity.

Custom patellofemoral arthroplasty of the knee. Surgical technique.

BACKGROUND: The treatment of isolated patellofemoral arthritis is controversial. Several surgical procedures have been used to treat the severely degenerated patellofemoral joint, with varying degrees of success. The purpose of this study was to determine the clinical results of a custom patellofemoral arthroplasty for the treatment of isolated patellofemoral degenerative arthritis of the knee. METHODS: From 1995 through 2002, twenty-five patellofemoral replacements, three of which were bilateral, were performed in twenty-two patients for the treatment of isolated patellofemoral arthritis of the knee. According to the Ahlback radiographic evaluation scale, the mean preoperative score for the severity of the arthritis was 4.65 points in the patellofemoral compartment and 0.5 point in both the medial and the lateral compartment. The patients included sixteen women (two of whom had a bilateral replacement) and six men (one of whom had a bilateral replacement) with a mean age of forty-five years at the time of the index arthroplasty. Seventeen patients (nineteen knees) had had a prior procedure on the knee. The mean preoperative Knee Society functional score was 49 points, and the mean preoperative Knee Society objective score was 52 points. RESULTS: At a mean of seventy-three months (range, thirty-two to 119 months) postoperatively, all twenty-five implants were in place and functioning well. There were eighteen excellent and seven good results. The mean Knee Society functional score was 89 points, and the mean Knee Society objective score was 91 points. No patient had required additional surgery or had component loosening. CONCLUSIONS: On the basis of our relatively short-term follow-up study, custom patellofemoral arthroplasty appears to be a safe and effective treatment for isolated patellofemoral arthritis of the knee. We believe that the results presented in this paper justify the additional cost associated with the custom device.

Custom patellofemoral arthroplasty of the knee.

BACKGROUND: The treatment of isolated patellofemoral arthritis is controversial. Several surgical procedures have been used to treat the severely degenerated patellofemoral joint, with varying degrees of success. The purpose of this study was to determine the clinical results of a custom patellofemoral arthroplasty for the treatment of isolated patellofemoral degenerative arthritis of the knee. METHODS: From 1995 through 2002, twenty-five patellofemoral replacements, three of which were bilateral, were performed in twenty-two patients for the treatment of isolated patellofemoral arthritis of the knee. According to the Ahl-back radiographic evaluation scale, the mean preoperative score for the severity of the arthritis was 4.65 points in the patellofemoral compartment and 0.5 point in both the medial and the lateral compartment. The patients included sixteen women (two of whom had a bilateral replacement) and six men (one of whom had a bilateral replacement) with a mean age of forty-five years at the time of the index arthroplasty. Seventeen patients (nineteen knees) had had a prior procedure on the knee. The mean preoperative Knee Society functional score was 49 points, and the mean preoperative Knee Society objective score was 52 points. RESULTS: At a mean of seventy-three months (range, thirty-two to 119 months) postoperatively, all twenty-five implants were in place and functioning well. There were eighteen excellent and seven good results. The mean Knee Society functional score was 89 points, and the mean Knee Society objective score was 91 points. No patient had required additional surgery or had component loosening. CONCLUSIONS: On the basis of our relatively short-term follow-up study, custom patellofemoral arthroplasty appears to be a safe and effective treatment for isolated patellofemoral arthritis of the knee. We believe that the results presented in this paper justify the additional cost associated with the custom device. LEVEL OF EVIDENCE: Therapeutic Level IV. See Instructions to Authors for a complete description of levels of evidence.

Accurate femur repositioning is critical during intraoperative total hip arthroplasty length and offset assessment.

Techniques for intraoperative leg length equalization are based on measurements between fixed points on the pelvis and femur. These techniques have not been reliable because they are based on accurate femur repositioning. We examined the error that results from inaccurate femur repositioning during total hip arthroplasty. Total hip arthroplasty was simulated on a calibrated test bench and changes in leg length and femoral offset were measured. Before dislocation, the femur was held in neutral alignment. Total hip arthroplasty was simulated without changing length or offset and the femur was returned to neutral. Length and offset changes were measured with the femur held in 5 degrees and 10 degrees of abduction/adduction and flexion/extension. Five degrees of abduction/adduction malpositioning caused 8 mm of apparent change in leg length. Errors in femoral offset followed a similar trend. When using common techniques for intraoperative leg length equalization and offset restoration, inaccurate abduction/adduction repositioning of the femur with respect to the pelvis can cause substantial errors in the measurement of length and offset change.