What question did this study set out to answer?

To evaluate whether patients post-ACLR, who pass RTS assessments, have remaining strength and movement deficits.

February 12, 2026Open Access

Quadriceps Strength and Movement Patterns in Patients After ACLR Who Pass a Clinic-Based Return-to-Sport Testing Battery

Key Points

To evaluate whether patients post-ACLR, who pass RTS assessments, have remaining strength and movement deficits.
Conducted a cross-sectional study design with ACLR patients.
Participants completed clinic-based RTS tests including limb symmetry and various strength assessments.
Laboratory tests measured isometric quadriceps strength and rate of torque development using a dynamometer.
Utilized a 3D motion analysis system to examine biomechanics during jumping activities.
Peak isometric quadriceps strength was 7.6% lower in the involved limb (P < .001).
Isometric quadriceps rate of torque development was up to 20.9% lower in the involved limb (P < .001).
Isokinetic peak quadriceps strength was 4.9% lower in the involved limb (P = .003).
Biomechanical measures showed impaired loading of the injured limb with differences ranging from 6.6% to 67% (P < .005).

Abstract

Background: Passing a battery of return to sport (RTS) testing after anterior cruciate ligament reconstruction (ACLR) has been shown to reduce second injury rates. However, previously reported testing methods are inaccessible for most clinicians due to equipment, financial, and time constraints. Purpose: To assess whether patients after ACLR who pass a clinic-based RTS evaluation have residual strength and/or biomechanical deficits when tested compared with gold standard techniques. Study Design: Cross-sectional study; Level of evidence, 3. Methods: All participants passed a battery of clinic-based RTS tests—including ≥90% limb symmetry during isometric quadriceps strength, 1-repetition maximum isotonic knee extension, and 4 single-legged hop tests (single, crossover, triple, and 6-m timed)—as well as ≥90% on the Global Rating Scale and the International Knee Documentation Committee Subjective Knee Form 2000. Laboratory testing then included isometric quadriceps strength and rate of torque development (RTD) (90° of knee flexion) and isokinetic concentric quadriceps and hamstring strength (60 deg/sec) using an isokinetic dynamometer. An 8-camera, 2-force-plate, 3-dimensional motion analysis system was used to measure sagittal-plane joint angles and moments during bilateral and unilateral drop-vertical jumping. Paired t tests were conducted to assess interlimb differences. Results: In laboratory testing, the peak isometric quadriceps strength was 7.6% lower in the involved limb ( P < .001). The isometric quadriceps RTD was up to 20.9% lower in the involved limb ( P < .001). Isokinetically, the peak quadriceps strength was 4.9% lower in the involved limb ( P = .003), while the peak hamstring strength was 4.7% higher in the involved limb ( P = .017). All biomechanical measures demonstrated impaired loading of the injured limb with interlimb differences ranging from 6.6% to 67% ( P < .005). Conclusion: Passing clinic-based RTS testing resulted in laboratory-based strength ≥90% limb symmetry and a previously established target of isometric quadriceps strength of 3 N·m/kg. However, deficits in quadriceps RTD and movement asymmetries persisted despite passing clinical criteria.

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