Quadriceps Strength Does Not Associate With Gait Adaptation Ability in Individuals With Anterior Cruciate Ligament Reconstruction.

CONTEXT: Postoperative muscle weakness contributes to the development of aberrant gait biomechanics that persist after traditional anterior cruciate ligament reconstruction (ACLR). However, it is unknown if quadriceps weakness impedes the ability of ACLR patients to modify gait biomechanics using a real-time gait biofeedback (RTGBF) intervention.

OBJECTIVE

The purpose was to determine if quadriceps strength is associated with the ability to modify vertical ground reaction force (vGRF) during a RTGBF intervention.

DESIGN

Cross-sectional study.

SETTING

Research laboratory.

PATIENTS OR OTHER

PARTICIPANTS

Thirty-five individuals with unilateral ACLR (time since ACLR = 32 ± 16 months; 22 females, 13 males).

MAIN OUTCOME MEASURE(S): Peak vGRF (pvGRF) was evaluated during a baseline walking trial and three 250-step randomized RTGBF walking trials, by 5%, 10%, or 15% body weight (BW). The ability to modify gait was reported as changes in pvGRF (ΔpvGRF; body weight [BW]) and root mean square error (RMSE) of the peak vGRF relative to the feedback target (pvGRF RMSE; BW). We also calculated quadriceps strength.

RESULTS

No significant associations were found between strength (mean = 2.56 ± 0.75 Nm/kg; range, 0.84-4.6 Nm/kg) and ΔpvGRF (5% ΔpvGRF: 0.04 ± 0.03 BW, 10% ΔpvGRF: 0.10 ± 0.03 BW, 15% ΔpvGRF: 0.15 ± 0.04 BW) nor strength and RMSE (5% RMSE: 0.04 ± 0.02 BW, 10% RMSE: 0.05 ± 0.02 BW, 15% RMSE: 0.08 ± 0.04 BW) for any of the 3 RTGBF trials (R2 = 0.003-0.025; P = .37-.77).

CONCLUSIONS

The magnitude of quadriceps strength did not influence the ability to modify gait using RTGBF. These data suggest that it may be unnecessary to wait for quadriceps full strength recovery to capitalize on the benefits of RTGBF after ACLR.