Hamstrings and Quadriceps Muscles Function in Subjects with Prior ACL Reconstruction Surgery

Area of Science:

• Orthopedics
• Sports Medicine
• Rehabilitation Science

Background:

• Knee joint injuries are common in young individuals.
• Anterior cruciate ligament (ACL) reconstruction is a frequent surgical intervention.
• Assessing long-term functional deficits post-ACL surgery is crucial for patient outcomes.

Purpose of the Study:

• To quantify skeletal muscle endurance and strength in individuals with a history of ACL knee reconstruction.
• To compare muscle performance between the injured and non-injured limbs.

Main Methods:

• Study included young, healthy female subjects over one year post-ACL reconstruction.
• Skeletal muscle endurance index (EI) measured via electrical stimulation (2-6 Hz).
• Maximal isometric muscle strength (MVC) assessed for hamstring and quadriceps.

Main Results:

• Hamstring muscle endurance was significantly lower in the injured leg at 6 Hz stimulation (p < 0.01).
• Quadriceps muscle endurance showed no significant difference between legs at 6 Hz stimulation (p = 0.45).
• No significant differences in maximal isometric muscle strength (MVC) were observed for either muscle group.

Conclusions:

• Reduced hamstring muscle endurance persists at least one year after ACL reconstruction.
• Recovered hamstring strength does not equate to restored muscle endurance.
• Inadequate endurance training during rehabilitation may contribute to persistent deficits and re-injury risk.