ABSTRACT
CONTEXT: Ambiguity exists in the literature regarding whether individuals can restore function to 100% after anterior cruciate ligament (ACL) reconstruction. The response of force production and reactive strength in stretch-shortening cycle activities after surgery has not been established. OBJECTIVE: To compare reactive strength and force production capabilities between the involved and uninvolved legs of participants who had undergone ACL reconstruction and rehabilitation with the reactive strength and force production capabilities of a control group. DESIGN: Repeated measures, cross-sectional. SETTING: Research laboratory. PATIENTS OR OTHER PARTICIPANTS: Ten participants with ACL reconstructions who had returned to their chosen sports and 10 age-matched and activity-matched control subjects. INTERVENTION(S): We screened the ACL group with the International Knee Documentation Committee Subjective Knee Evaluation Form and functional performance tests to measure a basic level of function. We assessed force production capabilities and reactive strength using squat, countermovement, drop, and rebound jump protocols on a force sledge apparatus. MAIN OUTCOME MEASURE(S): The dependent variables were flight time, peak vertical ground reaction force, leg spring stiffness, and reactive strength index. RESULTS: No participant in the ACL group exhibited functional deficits in comparison with normative values or the control group. Using the force sledge apparatus, we found no notable differences in force production capabilities and reactive strength in the ACL group when comparing the involved with uninvolved legs or the degree of difference between legs with the control group. CONCLUSIONS: After ACL reconstruction, rehabilitated participants did not exhibit deficits in force production or reactive strength capabilities. Our results suggest that force production and reactive strength capabilities can be restored to levels comparable with the uninjured control limb and may not be limiting factors in ACL recovery.
