The Incidence of Injuries to Ramp Semimembranosus Complex Lesions After ACL Injury: An MRI Study

Area of Science:

• Orthopedic Surgery
• Sports Medicine
• Knee Injuries

Background:

• Medial meniscal ramp lesions are increasingly recognized, particularly with anterior cruciate ligament (ACL) ruptures.
• The ramp semimembranosus complex (RSC) involves the meniscocapsular ligament, semimembranosus muscle, and meniscotibial ligament.
• Diagnosing RSC injuries is challenging, potentially leading to underestimation compared to isolated ramp lesions.

Purpose of the Study:

• To determine the prevalence of ramp semimembranosus complex (RSC) lesions in patients with complete anterior cruciate ligament (ACL) ruptures.

Main Methods:

• Retrospective analysis of 100 patients with confirmed ACL rupture undergoing knee arthroscopy.
• MRI evaluation by two musculoskeletal radiologists to identify semimembranosus lesions.
• Arthroscopic confirmation of ramp lesions and assessment of rotational instability using the pivot-shift test.

Main Results:

• Over half (53%) of the 100 patients with ACL ruptures exhibited RSC lesions.
• MRI identified 40 semimembranosus lesions, with 30 confirmed as ramp lesions during arthroscopy.
• A positive pivot-shift test, indicating rotational instability, was more frequent in patients with combined ACL and RSC injuries (57%) than without (36%).

Conclusions:

• Ramp semimembranosus complex (RSC) lesions are prevalent in over half of anterior cruciate ligament (ACL) ruptures.
• Combined ACL and RSC injuries may be associated with increased rotational instability.