In vitro comparison of elongation of the anterior cruciate ligament and single- and dual-tunnel anterior cruciate ligament reconstructions.

This study evaluated strain in the normal anterior cruciate ligament (ACL) and compared it to four different double-strand hamstring tendon reconstructive techniques. Seventeen fresh-frozen knees from 11 cadavers were tested. The strain in the anteromedial and posterolateral bands of the native ACL and their equivalents in four autograft techniques were measured using differential variable reluctance transducers. The anteromedial band of the intact ACL shortened from 0 degree -30 degrees of flexion, then lengthened to 120 degrees; the posterolateral band of the intact ACL shortened from 0 degree - 120 degrees of flexion. Following ACL excision, these knees underwent reconstruction with double-strand hamstring tendons with either single tibial and femoral tunnels, single tibial and dual femoral tunnels, dual tibial and single femoral tunnels, or dual tibial and dual femoral tunnels. With the exception of the dual-band, dual-tunnel technique, all of the procedures placed greater strain on the reconstructive tissues than was observed on the native ACL, after approximately 30 degrees of flexion. These results indicate that dual-band hamstring tendon reconstructions placed with single tibial and femoral tunnels do not address the complexity of the entire ACL. Rather, these procedures appear to only duplicate the effect of the anteromedial band, while perhaps overconstraining the joint as a result of its inability to reproduce the function of the posterolateral band. During rehabilitation following ACL reconstruction, therefore, only from 0 degree - 30 degrees of the graft tissues are not significantly strained. Dual tibial and femoral tunnel techniques should be evaluated further to more closely recreate knee kinematics following ACL reconstruction.

The outcomes of two knee scoring questionnaires in a normal population.

The Noyes and Lysholm knee scoring questionnaires, commonly used for follow-up assessment after knee surgery, were developed based on knees with preexisting pathologic changes and have not been standardized to normal knees. We administered both questionnaires to normal subjects. Any subject reporting a history of injury or surgery to either knee, or preexisting knee pathologic changes, was excluded. From a total of 492 knees evaluated, 418 knees (253 male, 165 female) qualified for statistical analysis. The average age of the group was 17.6 years (range, 13 to 25). For male subjects, the total Noyes and Lysholm scores averaged 99.10 (range, 68 to 100) and 99.10 (range, 77 to 100), respectively. For female subjects, the average Noyes and Lysholm scores were 97.82 (range, 72 to 100) and 97.16 (range, 75 to 100), respectively. The 95% confidence interval computed for each of these groups did not contain the maximal value of 100. The female athletes reported significantly lower total scores than the male athletes on both questionnaires. For the Lysholm questionnaire, the male athletes scored significantly lower than the maximum in all categories except support and stair climbing, and the female athletes scored significantly lower than the maximum in all categories except limp and thigh atrophy. The range of scores found in this highly selected, "normal" population exemplifies the need for more accurate instruments in the evaluation of knee surgical outcomes.

Myoelectric and mechanical changes elicited by ischemic preconditioning in the feline hindlimb.

Tourniquet use is fraught with potential complications. For example, ischemia produced by the tourniquet may lead to nerve and muscle injuries. One technique shown in cardiovascular and free-flap surgery to improve the viability of muscle subjected to ischemia is preconditioning. This technique involves an initial brief period of ischemia, followed by reperfusion before a prolonged ischemic episode. The purpose of this study was to explore ischemic preconditioning as a method to reduce tourniquet-related morbidity. In six cats, one leg was preconditioned by 10 min of tourniquet-induced ischemia followed by 10 min of reperfusion. The contralateral limb was not preconditioned. Both limbs underwent 1 h of tourniquet inflation followed by a 2-h recovery period. Isometric force and electromyographic (EMG) amplitude were recorded throughout the procedure at 20-min intervals in both medial gastrocnemius muscles. Analysis of variance (ANOVA) with repeated measures shows that, after 60 min of tourniquet application, maximal isometric force was significantly larger in the preconditioned group. Furthermore, the EMG amplitude during recovery was found to be significantly larger in the preconditioned limbs. These results suggest that preconditioning improves skeletal muscle viability in vivo. Further research is needed, however, to assess the long-term effects of this technique, and to delineate appropriate preconditioning protocols that would improve surgical outcome without significantly increasing the complexity of the procedures.

Traumatic hip dislocation during childhood. A case report and review of the literature.

Traumatic hip dislocations rarely occur during childhood. Males sustain pediatric hip dislocations four times more often than do females. Posterior hip dislocations comprise 87% of all pediatric hip dislocations. A soft, pliable acetabulum and ligamentous laxity predispose the immature hip joint to a dislocation secondary to minimal trauma. Potential associated injuries include fractures and neurovascular injury, whereas avascular necrosis (AVN) and degenerative joint disease are potential sequelae. Optimal treatment should be prompt reduction of the hip in order to minimize the risk of AVN of the femoral head.