Quadriceps Neuromuscular Performance In Mid- And Late-phase Rehabilitation Following Anterior Cruciate Ligament Reconstruction With A Quadriceps Tendon Autograft

Neuromuscular studies following anterior cruciate ligament reconstruction with a quadriceps tendon autograft (QT-ACLR) suggest reduced quadriceps performance in the involved versus the uninvolved limbs at least one year after surgery, but no data are available at earlier time points. PURPOSE: This work aimed to provide initial results on quadriceps peak torque (PT) across mid and late rehabilitation phases following QT-ACLR. We hypothesized that the mid-phase group would show lower PT at all isokinetic speeds compared to the late-phase group in the involved limbs, but both groups would show deficits in their involved compared to uninvolved limbs across all speed conditions. METHODS: 31 patients (Mid – M/F: 8/7, Age: 26.8 ± 9.6 years, Time Since Surgery: 26.2 ± 3.2 weeks; Late – M/F: 10/6, Age: 27.4 ± 10.1 years, Time Since Surgery: 46.6 ± 8.5 weeks) with QT-ACLR were tested on an isokinetic dynamometer either >5-to-8 months (mid-phase) or >8-to-15 months (late-phase) after surgery. Isokinetic testing was conducted for knee extension and flexion at 60, 180, and 300 deg·s-1. Quadriceps’ PT was extracted from three consecutive repetitions at each speed. A mixed repeated measures ANOVA (leg x speed x phase) with LSD post hoc testing was used to determine significant main effects or interactions among factors. RESULTS: A significant interaction (leg x speed x phase) was found for PT (F[2,58]=6.329, p < .05, η2 = .179, observed power = .884). Post hoc comparisons showed significantly lower PT in the involved limbs of mid- compared to late-phase across 60 (MD±SE: -51.20 ± 17.48 Nm, p < .01, Cohen’s d = 1.05), 180 (MD±SE: -32.74 ± 13.74 Nm, p < .05, Cohen’s d = .86), and 300 (MD±SE: -30.58 ± 11.59 Nm, p < .05, Cohen’s d = .93) deg·s-1. No significant differences were found between groups for the uninvolved limb. For the mid-phase group, the involved limb produced significantly lower PT than the uninvolved limb at all speeds, whereas the late-phase group produced lower PT at 60 (p < .01) and 180 (p < .05), but not 300 deg·s-1 (p = .144). Lastly, for both groups and in both limbs, there was a significant reduction in PT across speeds. CONCLUSION: Mid- and late-phase recovery of quadriceps PT is not evident in the current work, but recovery of PT at 300 deg·s-1 may be an important milestone in return to sport following QT-ACLR.