Beyond peak torque: Longitudinal analysis of angle-specific isokinetic knee torques in collegiate athletes post-ACLR.
Umut Z Kocak, Keith A Knurr, Daniel G Cobian and 1 others
PMID 36841117WHAT IT FOUND
Collegiate athletes with bone-patellar tendon-bone grafts showed quadriceps asymmetry at deep knee flexion angles until 8 months post-surgery, resolving by 12 months.
Testing at both 60°/s and 240°/s speeds yielded similar results, suggesting one speed may be sufficient.
Key findings
01Operated limb knee extensor torque was lower than the non-operated limb at 4 and 8 months, but no significant between-limb differences remained at 12 months.
02Asymmetries in the operated limb were detected across a wide range of knee flexion angles (25-91°) at 4 months, narrowing to specific deep flexion angles (65-90°) by 8 months.
03Knee extensor torque changes at the faster 240°/s speed mirrored those at 60°/s, with no additional discrimination for return-to-sport timing, suggesting testing at both speeds may be redundant.
STILL TO COME
How it was doneWhat they foundWhat it means for PTs
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What it does not show
The sample size was small (n=17), which limits the precision of identifying exact angles of deficit and reduces the power to detect smaller, potentially clinically relevant differences, especially in sex-specific analyses. The study included only collegiate athletes with bone-patellar tendon-bone grafts, so findings may not generalize to recreational athletes or those with hamstring or quadriceps tendon grafts. Some athletes had concomitant meniscal repairs or ligament reconstructions, which could influence recovery patterns and torque deficits. The statistical approach used a Bonferroni correction, which is conservative and may have increased the risk of missing smaller significant effects. Isokinetic testing at the outer bounds of the range of motion (particularly at 240°/s) may be affected by acceleration/deceleration phases, requiring cautious interpretation of torque data at extreme angles.
Declared interests
The authors declared no conflicts of interest. The study was approved by the University’s Health Sciences Institutional Review Board as a records review.
The easy way to misread this
Do not assume that the absence of between-limb asymmetry at 12 months means the athlete is fully recovered or ready for unrestricted sport. The study used a conservative statistical method that may have missed smaller deficits, and peak torque values (which were not the primary focus of the angle-specific analysis) often remain asymmetric beyond 1 year. Additionally, these findings apply specifically to collegiate athletes with bone-patellar tendon-bone grafts and may not extend to other populations or graft types.