Ankle kinematics and muscle activity in functional ankle instability.

OBJECTIVE: Following an ankle injury, many patients have functional ankle instability (FAI) with an increased predisposition to reinjury. The purpose of this study was to assess the effects of FAI on ankle kinematics and muscle activity during a lateral hop movement. DESIGN: Cross-sectional and observational study; all data collection for each subject was performed on 1 day. SETTING: Clinical biomechanics laboratory. PATIENTS: Two groups were studied: (1) Control group-no ankle injury (n = 12), and (2) FAI group (n = 12). INTERVENTIONS: The lateral hop movement consisted of multiple lateral and medial 1-legged hops over an obstacle (width, 72.5 cm; depth, 25.5 cm; height, 14.3 cm) onto adjacent force platforms. Each subject was instructed to perform as many lateral hops as possible during the 6-second trial. Means, SDs, 95% confidence intervals of the differences, and P-values were calculated. MAIN OUTCOME MEASURES: Ankle kinematics and muscle activity throughout the lateral hop movement. RESULTS: Significant differences existed between groups for mean (SD) dorsiflexion ankle positions--FAI 82.4 degrees (6.4) versus normal 75.2 degrees (10.1) and tibialis anterior normalized muscle activity--FAI 0.27 (0.21) versus normal 0.16 (0.13) at ground contact. CONCLUSIONS: The FAI group revealed greater tibialis anterior muscle activity and dorsiflexion ankle position at contact moving in the lateral direction. These differences between groups may have been related to an inherent predisposition to ankle injuries, a preexisting difference in task performance, a consequence of injuries, or a compensatory adaptation to previous injuries.

Lateral hop movement assesses ankle dynamics and muscle activity.

Ankle function is frequently measured using static or dynamic tasks in normal and injured patients. The purpose of this study was to develop a novel task to quantify ankle dynamics and muscle activity in normal subjects. Twelve subjects with no prior ankle injuries participated. Video motion analysis cameras, force platforms, and an EMG system were used to collect data during a lateral hop movement task that consisted of multiple lateral-medial hops over an obstacle. Mean (SD) inversion ankle position at contact was 4.4° (4.0) in the medial direction and -3.5° (4.4) in the lateral direction; mean (SD) tibialis anterior normalized muscle activity was 0.11 (0.08) in the medial direction and 0.16 (0.13) in the lateral direction. The lateral hop movement was shown to be an effective task for quantifying ankle kinematics, forces, moments, and muscle activities in normal subjects. Future applications will use the lateral hop movement to assess subjects with previous ankle injuries in laboratory and clinical settings.

Knee immobilization for pain control after a hamstring tendon anterior cruciate ligament reconstruction: a randomized clinical trial.

BACKGROUND: This study will attempt to evaluate the efficacy of knee immobilization on patient pain levels after an anterior cruciate ligament reconstruction. HYPOTHESIS: There is no difference in visual analog scale pain scores 2 days after anterior cruciate ligament reconstruction between patients who wear a knee immobilizer and those who do not wear a knee immobilizer. STUDY DESIGN: Randomized clinical trial; Level of evidence, 1. METHODS: Patients aged 18 to 40 years who met study inclusion criteria were eligible. Patients meeting intraoperative inclusion criteria were randomized (immobilizer or no immobilizer) after wound closure. The immobilizer used was a soft, unhinged brace with Velcro straps. Preoperative, intraoperative, and postoperative protocols were standardized. The primary outcome was patient self-assessed pain using a 0-to-100-mm visual analog scale at day 2 after surgery. Secondary outcomes included pain and analgesic use in the first 14 days after surgery, complications, and range of motion (approximately 3 weeks postoperatively). A sample size estimate was calculated and resulted in the need for 44 patients per group. RESULTS: A total of 102 patients were enrolled; 88 patients were randomized, and 14 were excluded intraoperatively. There was no difference in mean visual analog scale pain scores at 2 days after surgery between immobilized and nonimmobilized patients (32.6 and 35.2, respectively; P = .59; difference, -2.6; 95% confidence interval, -12.2 to 6.9). There were no differences between groups in medication consumed, range of motion, or complications. Pain and analgesic use were the same for both groups at 7 and 14 days postoperatively. CONCLUSION: No differences in pain or any of the secondary outcomes were detected between immobilized and nonimmobilized patients at any point during the first 14 days after anterior cruciate ligament reconstruction.