Clinical evaluation of the modified Brostrom-Evans procedure to restore ankle stability.

The modified Brostrom procedure has become the standard for anatomic repair of symptomatic chronic lateral instability. However, it was our perception that this local tissue repair may fail eventually, particularly in patients that are overweight, hyperflexible, or are involved in strenuous work or athletic activity. This is a retrospective review of 21 lateral ankle reconstructions (20 patients) in which the modified Brostrom technique was augmented with a portion of the peroneus brevis tendon. All patients were interviewed at an average of 29.5 months (range, 14-56 months postsurgery). Fourteen patients also agreed to be evaluated by a physical therapist. No surgical complications were identified. American Orthopaedic Foot and Ankle Society ankle-hindfoot scores averaged 98.2. There was no significant difference in passive or active range of motion of plantarflexion or dorsiflexion when compared to the contralateral ankle. However, a statistically significant loss of inversion (passive, P = 0.011; active, P = 0.018) and eversion (passive, P = 0.004; active, P = 0.007) was noted when compared to the contralateral ankle. Measurement of isometric eversion strength, using a Cybex 340 Isokinetic device, and functional testing, using a lateral lunge test, revealed no significant loss of peroneal strength. The authors conclude that chronic lateral ankle instability in the general population can be successfully managed with a modified Brostrom procedure augmented with a portion of the peroneus brevis. The procedure remains technically simple and provides a greater static restraint for inversion stress without evidence of dramatic overtightening or loss of peroneal strength.

EMG analysis of lower extremity muscle recruitment patterns during an unloaded squat.

During an unloaded squat, hamstring and quadriceps co-contraction has been documented and explained via a co-contraction hypothesis. This hypothesis suggests that the hamstrings provide a stabilizing force at the knee by producing a posteriorly-directed force on the tibia to counteract the anterior tibial force imparted by the quadriceps. Research support for this hypothesis, however, is equivocal. Therefore, the purposes of this study were 1) to determine muscle recruitment patterns of the gluteus maximus, hamstrings, quadriceps, and gastrocnemius during an unloaded squat exercise via EMG and 2) to describe the amount of hamstring-quadriceps co-contraction during an unloaded squat. Surface electrodes were used to monitor the EMG activity of six muscles of 41 healthy subjects during an unloaded squat. Each subject performed three 4-s maximal voluntary isometric contractions (MVIC) for each of the six muscles. Electrogoniometers were applied to the knee and hip to monitor joint angles, and each subject performed three series of four complete squats in cadence with a metronome (50 beats.min-1). Each squat consisted of a 1.2-s eccentric, hold, and concentric phase. A two-way repeated measures ANOVA (6 muscles x 7 arcs) was used to compare normalized EMG (percent MVIC) values during each arc of motion (0-30 degrees, 30-60 degrees, 60-90 degrees, hold, 90-60 degrees, 60-30 degrees, 30-0 degrees) of the squat. Tukey post-hoc analyses were used to quantify and interpret the significant two-way interactions. Results revealed minimal hamstring activity (4-12% MVIC) as compared with quadriceps activity (VMO: 22-68%, VL: 21-63% of MVIC) during an unloaded squat in healthy subjects. This low level of hamstring EMG activity was interpreted to reflect the low demand placed on the hamstring muscles to counter anterior shear forces acting at the proximal tibia.