A Multi-Modal Approach to Knee Flexor Strength Assessment after ACLR: a Case Report

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Physical Therapy


The purpose of this case report was to reveal positional strength deficits of the knee flexors, clinically evaluated through several means, in a collegiate basketball athlete after anterior cruciate ligament reconstruction (ACL-R). Lower extremity strength assessment is a component of a comprehensive return-to-sport testing battery after ACL-R. Persistent knee flexion weakness, in those with hamstring autografts, has been demonstrated up to 18-months post ACL-R in various testing positions using isokinetic and isometric dynamometry, yet knee flexor strength is often assessed solely through isokinetic testing during return-to-sport (RTS) assessment. Knee flexor strength was assessed through seated isokinetic dynamometry (60°/sec) at 6 months postoperatively. Additional methods of knee flexor strength assessment were performed at the 7, 8, and 9-month postoperative timeframes including isometric handheld dynamometry in prone and seated positions, in addition to 10-repetition maximum (10 RM) testing using a prone hamstring curl. The patient achieved the desired 90% limb symmetry index (LSI) for seated isokinetic knee flexion strength testing at 6-months post-operatively. Seated isometric strength LSI remained greater than 100% over the duration of the testing timeframe. Prone isometric strength assessment revealed LSI of 65% at 7 months but improved to 69% by 9 months postoperatively. Improvements in knee flexor strength were observed via prone hamstring curl 10 RM testing, progressing from 56 % at 7 months to 95% LSI at 9 months, respectively. While RTS is multifactorial, knee flexor strength assessment using various testing positions and methods may offer clinicians useful information to aid in RTS decision making and rehabilitation program design. Additional research is required to examine the implications of knee flexor strength assessment with respect to patient outcomes.

First Advisor

Brandon Ness

Research Area

Physical Therapy

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