Electrothermally-assisted capsular shift.

The marriage of biomedical instrumentation and patient care has once again proven itself successful. The ETAC is a new procedure with various potential applications. Despite its embryonic stage, this procedure is being used by a handful of shoulder surgeons who are cautiously pursuing new and improved ways to prevent the common and debilitating diagnosis of shoulder instability. Follow-up thus far is short, and the current literature lacks studies that compare the time-honored conventional standard of open stabilization to this new procedure. However, those surgeons who have been using this device are optimistic about its role in the future repair of shoulder injuries.

Biomechanical assessment of the healing response of the rabbit patellar tendon after removal of its central third.

The objective of this study was to determine the biomechanical properties of the healing patellar tendon after removal of its central third. This was accomplished by removing the central third of the patellar tendon from the right limb of 30 mature New Zealand White rabbits. The tendon of the contralateral normal limb served as the unoperated control. The rabbits were separated into five test groups according to healing time: time of surgery and 1, 2, 3, and 6 months after surgery. The ultimate failure strength of the patellar tendons with the central third removed was significantly less than the failure strength of the contralateral normal patellar tendons at all time intervals after surgery. At the time of surgery, the ultimate failure strength values of the operated patellar tendons were on average 53% of the normal patellar tendons, increasing to 72% of normal at 6 months. There was a significant correlation between the ultimate failure strength of the operated tendons and healing time. The positive slope for this regression indicated that the ultimate failure strength of the operated tendons converged toward normal as healing progressed. Failure mode of the operated tendon did not depend on healing time.

The correlation between anterior-posterior translation and cross-sectional area of anterior cruciate ligament reconstructions.

Total anterior-posterior translation is commonly used to assess the integrity of the cruciate ligaments and the success of reconstructive surgery. The purpose of this study was to determine, after surgical reconstruction of the anterior cruciate ligament with a biological graft, if total anterior-posterior translation correlated with graft length, cross-sectional area, or mechanical properties. These factors were investigated by analyzing data from three previous studies. These studies involved replacement of the anterior cruciate ligament in cynomolgus monkeys and goats, with free and vascularized patellar tendon autografts and both patellar tendon and anterior cruciate ligament allografts. Data were available at time periods of 6 and 12 months after surgery. We found statistically significant inverse correlations between the amount of anterior-posterior translation and cross-sectional area of a graft at the time of sacrifice. The Pearson correlation coefficients ranged from -0.966 (p < 0.002) to -0.830 (p < 0.05). We hypothesize that these correlations result from the following mechanism: the increased anterior translation reflects a slack graft; a slack graft is stress shielded by other structures about the knee; the reduced in vivo stresses on the graft modulate cellular metabolism in a way that over time produces a small cross-sectional area.

Resection of bucket-handle meniscus tears: a simple technique using a Beaver blade.

This article describes a simple technique for the use of a #66 Beaver blade to assist in the resection of bucket-handle meniscus tears. This is a standard ophthalmologic blade and should be readily available in most operating rooms. The technique described is a simple, inexpensive means of resecting bucket-handle tears without changing portals during the procedure.

Anterior cruciate ligament reconstruction using bone-patellar tendon-bone allografts. A biological and biomechanical evaluation in goats.

Twenty-eight goats underwent ACL reconstruction with freeze-dried bone-patellar tendon-bone allografts in one knee, the opposite knee serving as a control. One group of 16 knees was evaluated, in groups of four, at 6, 12, 26, and 52 weeks by histologic and vascular injection techniques. The other group of 12 knees was evaluated in two groups of six at 26 and 52 weeks by morphological and biomechanical techniques of analysis. Within the first 12 weeks these allografts were revascularized; in the first 26 weeks they had matured to resemble normal connective tissue. Graft stiffness was 29% of the control value and maximum force to failure was 43% of the control value. The results of this study indicated that freeze-dried bone-patellar tendon-bone allografts are biomechanically and biologically similar to patellar tendon autografts.

Principles of bracing for the anterior cruciate ligament-deficient knee.

The preceding discussion has profiled the three different types of knee braces available on today's market. It has attempted to discuss the controversies surrounding these braces and to analyze the scientific data presented to date. Prophylactic braces have been shown to be ineffective in preventing knee injuries in their present-day design. Evidence has also shown that their use may even lead to increased knee injuries. On the other hand, rehabilitative braces do serve a useful purpose in regard to the operative and nonoperative treatment of ligamentous knee injuries. With their use in the application and control of joint motion, they are an important addition to the surgeon's armamentarium. One must keep in mind, however, that these braces provide little static anterior/posterior control and the hinge settings may not actually reflect true joint motion. Functional knee braces may play a role in the treatment of patients with pathologic laxity owing to an injury of the ACL. Combined with an adequate rehabilitation program and activity modification, these braces do limit excessive anterior tibial translation under low-loading conditions. However, under conditions of high loading these braces provide little or no resistance to anterior translation. Therefore, in most sporting activities, their efficacy is questionable. Knee bracing continues to be a complex and controversial topic in the field of orthopaedic surgery. The answers for the design of the "ideal" brace are being continually worked out and the need for more detailed, well-controlled studies continues to be great.(ABSTRACT TRUNCATED AT 250 WORDS)

Reconstruction of the anterior cruciate ligament with freeze dried fascia lata allografts in dogs. A preliminary report.

In 16 adult dogs the anterior cruciate ligament (ACL) was transected and then reconstructed using freeze dried fascia lata allografts. Eight of the dogs had the intraarticular graft passed through drill holes in the tibia and femur, while in the other eight dogs the graft was passed through a drill hole in the tibia and routed "over-the-top" of the lateral femoral condyle. In all dogs the grafts were then passed deep to the lateral collateral ligament and secondarily secured to the tibia as an extraarticular reconstruction. Specimens from each group underwent histologic study and biomechanical testing on a mechanical testing system at 3, 6, 12, and 24 week intervals. All grafts were found to be intact at sacrifice with no overt evidence of biologic incompatibility. The knees displayed only mild instability to clinical testing without evidence of arthrosis. Histologically, the grafts appeared to function as a collagenous scaffolding for revascularization and fibrovascular creeping substitution. The mean maximum load at failure in the 24 week specimens reached 536.44 N, compared to values of 801.85 N in contralateral knees with an intact ACL.