Pre-operative knee extensor and flexor torque after secondary ACL rupture: a comparative retrospective analysis

Area of Science:

• Orthopedics
• Sports Medicine
• Biomechanics

Background:

• Secondary anterior cruciate ligament (ACL) ruptures pose a significant clinical challenge post-primary ACL reconstruction.
• Limited scientific data exists on the pre-revision muscle strength in patients experiencing a second ACL rupture.
• Understanding pre-operative strength is crucial for optimizing outcomes in revision ACL surgery.

Purpose of the Study:

• To compare knee extensor and flexor muscle strength in patients undergoing primary ACL reconstruction.
• To assess knee extensor and flexor muscle strength in patients with secondary ACL ruptures before revision surgery.
• To compare these strength metrics against healthy, matched controls.

Main Methods:

• A cohort of 69 individuals was studied, including 23 with primary ACL rupture, 23 with secondary ACL rupture, and 23 healthy controls.
• Participants were matched for age, weight, and sex.
• Maximal isokinetic knee extension and flexion torque, normalized to body mass, were measured for both legs.

Main Results:

• Patients with secondary ACL ruptures exhibited significantly reduced knee extensor and flexor torques in both the injured and non-injured legs compared to controls.
• Patients with primary ACL ruptures also showed significantly reduced torques in both legs relative to healthy controls.
• No significant strength differences were observed between primary and secondary ACL rupture groups, except for higher knee extension torque in the injured leg of the secondary rupture group.

Conclusions:

• Maximal knee torques are substantially reduced in both primary and secondary ACL rupture patients prior to surgical reconstruction.
• These strength deficits are present in both the operated and contralateral limbs.
• Further prospective research is required to evaluate strength changes before and after revision ACL surgery.