Introduction: Anterior cruciate ligament reconstruction (ACLR) is common. Insufficient quadriceps strength and functional hop asymmetry are associated with an increased re-injury risk after ACLR upon return to sport (RTS). This study sought to investigate whether an accelerated rehabilitation pathway after ACLR with a hamstring autograft could enhance strength and functional symmetry after ACLR, without affecting graft laxity and/or re-injury.
Methods: A total of 44 patients were allocated to an ‘Accelerated’ (n=22) or ‘Control’ (n=22) rehabilitation intervention. While still criterion-focused, the Accelerated pathway permitted an earlier initiation of single limb stance and proprioceptive exercises (2 versus 4 weeks), squat and lunge activities (3 versus 4 weeks), single limb squat variations (5 versus 7 weeks), integration of jump and land exercises (9 versus 12 weeks) and gradated return to running (10 versus 14 weeks). Patients were assessed pre- and post-operatively (6 weeks, 4, 6, 9, 12 and 24 months) with surveys, graft laxity, peak isokinetic knee extensor and flexor strength and a 4-hop performance battery. Limb Symmetry Indices (LSIs) were calculated. Sport participation, secondary operations, ACL re-tears and contralateral ACL tears were reported.
Results: No differences (p˃0.05) existed in demographics or surveys, apart from the Anterior Cruciate Ligament Return to Sport after Injury (ACL-RSI) score which was significantly better (p=0.001) in the Accelerated group at 12 months. A significantly greater (p=0.006) percentage of Accelerated (77.3%) versus Control (59.1%) patients were participating in Level 1 or 2 pivoting sports at 12 months, though not different (p=0.836) at 24 months (Accelerated 86.4%, Control 85.7%). A significantly higher knee extensor strength LSI was observed in the Accelerated group at 6 (p<0.0001), 12 (p=0.010) and 24 (p=0.005) months, as was a significantly higher LSI for the triple hop for distance at 6 (p=0.015) and 9 (p=0.008) months, and the triple crossover hop for distance at 6 (p<0.0001) and 9 (p=0.009) months. No laxity differences or contralateral tears were observed, with one ipsilateral re-tear (Control group, 17 months). Four re-operations were undertaken, including n=1 in the Accelerated (meniscectomy) and n=3 in the Control (three meniscectomies) group.
Discussion: The accelerated pathway produced earlier improvement in strength and hop LSIs which have been linked with re-injury in patients that RTS after ACLR. Importantly, the accelerated regimen and increased early participation in pivoting sports was not associated with an increase in graft laxity or graft re-injury.
Impact and Application to the Field: Current evidence has demonstrated a link between strength and hop asymmetry and an increased re-injury risk in patients who RTS after ACLR. The current study has shown that a structured, accelerated rehabilitation pathway with therapist progression and oversight, can enhance these physical outcomes, without an increase in graft laxity and/or an elevated re-injury risk.
Conflict of Interest Statement: a funding grant was provided by Smith and Nephew to assist this research.