Evaluation of Thigh Muscle Strength in Adolescent Patients After Anterior Cruciate Ligament Reconstruction With Lateral Extra-articular Tenodesis or Anterolateral Ligament Reconstruction.

Background: There has been increased interest in lateral extra-articular procedures, such as anterolateral ligament reconstruction (ALLR) or lateral extra-articular tenodesis (LET), to reduce anterolateral rotation instability of the knee after anterior cruciate ligament reconstruction (ACLR). Despite promising surgical outcomes with these techniques, their impact on knee strength recovery is unknown.

Hypothesis: Patients undergoing lateral extra-articular procedures at the time of ACLR would have impaired thigh muscle strength at 6 to 9 months after surgery.

Study Design: Cohort study; Level of evidence, 3.

Methods: Adolescent patients who had undergone primary unilateral ACLR with lateral extra-articular augmentation between 2017 and 2023 were identified. Patients were included if they were aged between 12 and 20 years at the time of surgery and had completed an isokinetic strength assessment at 6 to 9 months after surgery. A total of 104 participants (mean age, 16.5 ± 1.7 years; 63 female) were included in this analysis: 25 who underwent ACLR+ALLR, 17 who underwent ACLR+LET, and 62 who underwent isolated ACLR. Isokinetic knee extension and flexion strength normalized to body weight, as well as the bilateral limb symmetry index (LSI), were assessed. One-way analysis of variance and analysis of covariance were used to compare differences between surgical techniques.

Results: After adjusting for age, graft type, and time since surgery, the ACLR+LET (1.36 ± 0.52 N·m/kg) and ACLR+ALLR (1.61 ± 0.53 N·m/kg) groups had significantly less involved limb knee extension strength ( = .025), uninvolved limb knee extension strength ( = .046), and LSI for knee extension strength ( = .040) compared to the isolated ACLR group. There were no differences between the 3 groups regarding involved limb knee flexion strength ( = .222) or uninvolved limb knee flexion strength ( = .984), but the isolated ACLR group displayed a greater LSI for knee flexion strength (96.6% ± 17.8%; = .012).

Conclusion: The addition of lateral extra-articular procedures at the time of ACLR was associated with decreased quadriceps strength at 6 to 9 months after ACLR. While lateral extra-articular procedures may enhance knee rotary stability after ACLR, prolonged rehabilitation may be needed to re-establish adequate quadriceps strength before return to sports.