Early Open Kinetic Chain Hamstring Exercise After ACL Reconstruction: A Retrospective Safety and Efficacy Study

Area of Science:

• Orthopedic Surgery
• Sports Medicine
• Rehabilitation Science

Background:

• Hamstring autografts for anterior cruciate ligament reconstruction (ACLR) often lead to persistent strength deficits and delayed recovery.
• Current rehabilitation guidelines conservatively delay open kinetic chain (OKC) hamstring exercises due to unproven safety concerns.

Purpose of the Study:

• To evaluate the safety and effectiveness of introducing OKC hamstring strengthening exercises early (3 weeks post-surgery) after ACLR.
• To challenge traditional rehabilitation protocols that delay hamstring loading.

Main Methods:

• An exploratory retrospective observational study involving 13 patients (18-35 years) who underwent ACLR with hamstring grafts.
• Participants performed isometric leg curls and glute bridges twice weekly starting 3 weeks post-op.
• Safety assessed via pain levels, hematoma, and hamstring strain; strength and endurance measured at 6 and 12 weeks.

Main Results:

• No major adverse events were reported; pain levels remained low throughout the study.
• Significant improvements in isometric knee flexion strength were observed between 6 and 12 weeks post-surgery.
• Limb symmetry index (LSI) at 90° knee flexion improved significantly, and functional gains in endurance were noted by 6 weeks.

Conclusions:

• Early introduction of OKC hamstring exercises (3 weeks post-ACLR) is safe and promotes meaningful improvements in strength and endurance.
• Findings challenge conservative rehabilitation, suggesting early hamstring loading may be beneficial.
• Larger randomized trials are needed to confirm these hypothesis-generating results and assess generalizability.