Effects of knee bracing on tibial rotation during high loading activities in anterior cruciate ligament-reconstructed knees.

PURPOSE: To test whether knee bracing restores normal rotational knee kinematics in anterior cruciate ligament (ACL)-reconstructed knees during high-demand, athletic activities. METHODS: Twenty male patients who had undergone unilateral ACL reconstruction with a bone-patellar tendon-bone autograft were assessed in vivo. The mean time from surgery to data collection was 26 months (range, 25 to 28 months). An 8-camera optoelectronic system was used to collect kinematic data while each patient performed 2 demanding tasks: (1) immediate pivoting after descending from a stair and (2) immediate pivoting after landing from a platform. Each task was performed under 3 conditions for the reconstructed knee: (1) wearing a prophylactic brace (braced condition), (2) wearing a patellofemoral brace (sleeved condition), and (3) without a brace (non-braced condition). As a control group, patients with intact ACLs were tested without any bracing. This study protocol was identical to the protocol of a previous study that investigated the effect of bracing on ACL-deficient athletes. RESULTS: For both tasks, the range of motion of tibial rotation was significantly lower in the intact knee compared with all 3 conditions of the ACL-reconstructed knee (P ≤ .014). Placing a brace or a sleeve on the ACL-reconstructed knee resulted in lower rotation than the non-braced condition (P ≤ .022), whereas no significant differences were found between the sleeved and the braced conditions (P ≥ .110). CONCLUSIONS: Bracing limited the excessive tibial rotation in ACL-reconstructed knees during pivoting that occurs under high-demand activities. However, full restoration to normative values was not achieved. Thereby, braces have the potential to decrease rotational knee instability that still remains after ACL reconstruction.

The effect of knee braces on tibial rotation in anterior cruciate ligament-deficient knees during high-demand athletic activities.

OBJECTIVE: To examine if bracing can restrict tibial rotation in anterior cruciate ligament (ACL)-deficient patients during high loading activities. DESIGN: Repeated measures. Kinematic data were collected with an 8-camera Vicon system while each patient performed 2 tasks that are known to cause increased rotational and translational loads on the knee: (1) descending from a stair and subsequent pivoting, and (2) landing from a platform and subsequent pivoting. The tasks were repeated under 3 brace conditions for the ACL-deficient knee: (1) wearing a prophylactic brace (braced condition), (2) wearing a patellofemoral brace (sleeved condition), and (3) without brace (unbraced condition). SETTING: Biomechanical laboratory study. PATIENTS: Twenty-one male subjects with a confirmed unilateral ACL rupture were assessed in vivo. MAIN OUTCOME MEASURES: Tibial internal rotation. Two repeated measures ANOVAs tested for differences in tibial internal rotation among the 3 conditions of the ACL-deficient knee and the unbraced condition of the intact knee. RESULTS: In both tasks, tibial rotation was significantly lower in the intact knee compared with all 3 conditions of the ACL-deficient knee (P ≤ 0.031). Bracing the ACL-deficient knee resulted in lower rotation than the unbraced (P ≤ 0.001) and sleeved (P ≤ 0.033) conditions. The sleeved condition resulted in lower tibial rotation in the drop landing and pivoting task compared with the unbraced condition (P = 0.019) but not in the stair descending and pivoting task (P = 0.256). CONCLUSIONS: Bracing decreased the excessive tibial rotation in ACL-deficient patients during high-demand activities but failed to fully restore normative values. If knee braces can enhance rotational knee stability in ACL-deficient patients, then they could possibly play an important role in preventing further knee pathology in such patients.

Knee braces can decrease tibial rotation during pivoting that occurs in high demanding activities.

PURPOSE: The purpose of this study was to investigate whether knee braces could effectively decrease tibial rotation during high demanding activities. METHODS: Using an in vivo three-dimensional kinematic analysis, 21 physically active, healthy, male subjects were evaluated. Each subject performed two tasks that were used extensively in the literature because they combine increased rotational and translational loads on the knee, (1) descending from a stair and subsequent pivoting and (2) landing from a platform and subsequent pivoting under three conditions: (A) wearing a prophylactic brace (braced), (B) wearing a patellofemoral brace (sleeved), and (C) unbraced condition. RESULTS: In the first task, tibial rotation during the pivoting phase was significantly decreased in the braced condition as compared to the sleeved condition (P = 0.019) and the non-braced condition (P = 0.002). In the second task, the same variable was significantly decreased in the braced condition as compared to the sleeved (P = 0.001) and the unbraced condition (P < 0.001). The sleeved condition also produced significantly decreased tibial rotation with respect to the unbraced condition (P = 0.021). CONCLUSIONS: Bracing decreased tibial rotation in activities where increased translational and rotational forces were applied. Because knee braces decreased tibial rotation, they can possibly be used with ACL-reconstructed and ACL-deficient patients to prevent such problems. LEVEL OF EVIDENCE: Case-control study, Level III.

Maximum intraoperative elongation of the rat sciatic nerve with tissue expander: functional, neurophysiological, and histological assessment.

The purpose of this study was to assess the maximum rapid intraoperative elongation of the rat sciatic nerve with the use of tissue expander, and its possible functional recovery. One hundred and eight rats were divided into five groups, and their right sciatic nerves were expanded with a 10-cc, 12-cc, 14-cc, 16-cc, and 18-cc expander, respectively, for 1 h. The functional recovery of the nerve was assessed at intervals up to 3 months, using the sciatic function index (SFI), neurophysiological indices, and histology. The maximum intraoperative elongation was observed in group IV (16-cc volume of tissue expander), at about 23.83%. SFI decreased between the first and seventh postoperative days, but gradually recovered, reaching preoperative values in all groups according to the formulas of De Medinaceli et al. (Exp. Neurol. 77:634-643, 1982) and Bain et al. (Plast. Reconstr. Surg. 83:129-136, 1989). Latency and motor conduction velocity demonstrated deterioration after expansion, which peaked after surgery. Recovery was gradually completed by the end of the experiment. The histological findings indicated minor aberrations immediately after expansion and maximal demyelination with axonal disruption on day 15. The reparative process started by day 30 and continued until day 90, when almost no histological changes were observed. In conclusion, intraoperative nerve expansion successfully elongates the rat sciatic nerve up to 23.83%. But it causes functional and morphological abnormalities, which are of moderate to severe degree, are of short duration, and are reversible. Intraoperative nerve expansion might be a valuable solution in the treatment of short nerve gaps, but its clinical application still needs to be evaluated.