Summary

Ultrasonography (US) is highly effective in detecting unstable meniscal ramp lesions in patients undergoing ACL reconstruction, with a 90% detection rate compared to 60% for MRI, though stable lesions were more challenging to identify using US.

Abstract

Introduction

Meniscal ramp lesions are posterior longitudinal tears at the meniscocapsular junction or meniscotibial ligament, which can result in residual anterior instability after anterior cruciate ligament (ACL) reconstruction surgery if not properly diagnosed and treated. These lesions are often missed in the anterior portal view of an arthroscope, making preoperative evaluation crucial. This study aimed to assess the effectiveness of ultrasonography (US) in detecting ramp lesions both preoperatively and intraoperatively. We hypothesized that US, with its dynamic assessment capabilities, would be superior in identifying unstable ramp lesions, while stable ramp lesions would be more challenging to visualize.

Methods

This nonrandomized, prospective trial was conducted on 82 knees that underwent ACL reconstruction between January 2022 and June 2023. Patients with a history of ipsilateral lower limb surgery or compound ligament injuries were excluded. Data collected included patient demographics (age, sex, height, weight), time from injury to first visit, time from injury to surgery, and the presence and type of ramp lesions identified via magnetic resonance imaging (MRI) and US (at the first visit to our department and on the day of surgery). Ramp lesions were classified based on Greif et al.'s criteria into stable and unstable types. To detect ramp lesions with ultrasound, patients were placed in the prone position with the knee flexed to approximately 70°. The probe was positioned just above the semimembranosus tendon to obtain a long-axis view. During isometric contraction in knee flexion, the presence of a hypoechoic space beneath the semimembranosus tendon was considered indicative of a ramp lesion. The test-retest reliability of US was assessed using the intraclass correlation coefficient (ICC) and analyzed using two-way random effects and absolute agreement models. The chi-square test was used to evaluate the association between US and MRI findings, while Student’s t-test compared groups based on the presence of ramp lesions. Statistical significance was set at p < 0.05.

Results

Ramp lesions were present in 12.2% of cases (10 of 82 knees). There was no significant difference in the demographics of patients with and without ramp lesions. On MRI, 60.0% (6 of 10 knees) of the cases had a ramp lesion. On initial ultrasound examination, 90.0% (9 of 10 knees) of cases presented with a ramp lesion, but 22.2% (2 of 9 knees) of these were poorly delineated on the day of surgery. Unstable ramp lesions were clearly delineated using US, whereas stable lesions were more difficult to detect. The reliability of US in identifying ramp lesions was high, with a kappa value of 1.000 for the first surgeon and an intra-observer reliability of 0.917 (0.844-0.956).

Conclusion

Unstable ramp lesions complicating ACL injuries could be effectively detected using US.