Quadriceps and hamstrings strength recovery during the first year after ACLR: Influence of sex and autograft in 520 patients active in pivoting sports

OBJECTIVE: To examine quadriceps and hamstrings strength recovery during the first year of rehabilitation after anterior cruciate ligament reconstruction (ACLR) and to evaluate whether strength recovery differ according to patient sex and autograft type. DESIGN: Registry study. SETTING: Primary care. PATIENTS: 520 patients (56% female) with an average age at ACLR of 23 ± 5.5 years reconstructed with either hamstring tendon (HT) autograft or patellar tendon (PT) autograft. MAIN OUTCOME MEASURES: Quadriceps and hamstrings strength recovery was analyzed and compared between sexes and autografts at 4, 8, and 12 months after ACLR. Limb symmetry index (LSI), mass-normalized strength (Nm/kg), and hamstrings-to-quadriceps strength ratio were used. Alpha level was set at p < 0.05. RESULTS: Differences in mass-normalized quadriceps and hamstrings strength of both limbs were observed between sexes at 4, 8, and 12 months, with males being stronger than females (p < 0.001). Patients with HT autograft had lower LSI and mass-normalized hamstrings strength, whereas patients with PT autograft had lower LSI and mass-normalized quadriceps strength (p < 0.001). CONCLUSION: Males had greater recovery of mass-normalized hamstrings strength, and higher mass-normalized strength values for quadriceps and hamstrings in both limbs compared to females. HT autograft was associated with lower hamstrings strength and PT autograft was associated with lower quadriceps strength after ACLR.