Hamstring weakness as an indicator of poor knee function in ACL-deficient patients

Area of Science:

• Orthopedics
• Sports Medicine
• Biomechanics

Background:

• Anterior cruciate ligament (ACL) rupture leads to knee joint instability and varying degrees of disability.
• Assessing muscle strength deficits is crucial for understanding functional limitations in athletes post-ACL injury.

Purpose of the Study:

• To investigate quadriceps and hamstring strength in ACL-deficient amateur soccer players across different functional levels.
• To correlate muscle strength deficits with functional status using the Lysholm score.

Main Methods:

• Thirty male amateur soccer players with ACL deficiency were stratified into high (L1), intermediate (L2), and low (L3) functional groups based on Lysholm scores.
• A control group of 12 amateur soccer players was included for comparison.
• Isokinetic strength assessment of quadriceps and hamstrings at 60 degrees/s was performed on injured and intact knees.

Main Results:

• Significant quadriceps strength deficits were observed in the injured knee across all functional groups (L1: 13.7%, L2: 16.0%, L3: 18.6%).
• Hamstring weakness was significant only in the low-function group (L3: 19.2%), while L1 (2.4%) and L2 (5.6%) showed deficits comparable to the control group.
• Quadriceps weakness was consistent across all groups, whereas hamstring strength deficit correlated with poorer knee function.

Conclusions:

• Quadriceps weakness is a common finding after ACL rupture in soccer players, irrespective of functional status.
• Hamstring weakness serves as a key indicator of poor knee function and inability to compensate for instability in ACL-deficient athletes.
• Strength deficits in the hamstrings, particularly in lower-functioning groups, highlight the importance of targeted rehabilitation for improving knee stability and function.