Isokinetic Testing After Anterior Cruciate Ligament Injury Showed a Greater Hamstrings/Quadriceps Ratio at 240°/S Over 6 Months From Injury but No Difference of Limb Symmetry Index

Abstract

Purpose: To assess preoperative quadriceps and hamstring strength at various time points after anterior cruciate ligament (ACL) injury but before ACL reconstruction. Methods: Patients who underwent isokinetic muscle strength testing before planned ACL reconstruction were included. Patients were placed in 1 of the following 3 groups on the basis of time from injury to testing: <3 months, 3 to 6 months, and 6 to 12 months. Among these 3 groups, hamstring and quadriceps limb symmetry index (LSI) and hamstring/quadriceps (H/Q) ratios were compared. A total of 100 patients were included (<3 months [n = 55]; 3-6 months [n = 31]; and 6-12 months [n = 14]). Results: There were no significant differences between patients in the 3 groups in regards to age, body mass index, or flexion range of motion, but there was a greater proportion of female patients in the 6 to 12 month group than the other groups. No significant differences in quadriceps or hamstring strength were noted among the 3 groups. H/Q ratio was significantly greater in the 6 to 12 month group than the less than 3 months and 3 to 6 months groups, with concentric testing at 240°/s. No correlation was found between patient sex and LSI or H/Q ratios. Conclusions: Patients who underwent isokinetic muscle strength testing 6 to 12 months after ACL injury had a greater H/Q ratio at 240°/s than those who were testing within 6 months of injury. No differences in hamstring or quadriceps LSI were noted on the basis of time. Clinical Relevance: An understanding of the factors that influence preoperative isokinetic muscle strength testing (including time from injury to surgery) is important, given associations noted between preoperative strength and postoperative strength recovery after ACL reconstruction.