The potential of posterior cruciate ligament buckling phenomenon as a sign for partial anterior cruciate ligament tears.

INTRODUCTION: Diagnosis of a partial tear of the anterior cruciate ligament (ACL) can be challenging with physical examination and imaging techniques. Although magnetic resonance imaging (MRI) has high sensitivity and specificity for diagnosing complete ACL tears, its effectiveness may be limited when it is used to diagnose for partial tears. The hypothesis of the present study is that the posterior cruciate ligament (PCL) buckling phenomenon, which is a secondary sign of complete ACL tears on MRI, may be a useful method for diagnosing partial ACL tears. MATERIALS AND METHODS: The data of 239 patients who underwent knee arthroscopy in a single institution between 2016 and 2022 were analyzed retrospectively. Patients were divided into three groups based on the condition of their ligaments: partial tears, complete tears and intact ligaments. To evaluate the buckling phenomenon on sagittal T2-weighted MRI, measurements of the posterior cruciate ligament angle (PCLA) and the posterior cruciate ligament-posterior cortex angle (PCL-PCA) were conducted in each group. Subsequently, the ability of these two measurement methods to distinguish partial tears from the other groups was assessed. RESULTS: Both methods provided significantly different results in all three groups. Partial tears could be distinguished from intact ligaments with 86.8% sensitivity, 89.9% specificity when PCLA < 123.13° and 94.5% sensitivity, 93.2% specificity when PCL-PCA < 23.77°. Partial tears could be distinguished from complete tears with 79.5% sensitivity, 78.4% specificity when PCLA > 113.88° and with 86.1% sensitivity, 85.3% specificity when PCL-PCA > 16.39°. CONCLUSION: The main finding of the present study is that the PCLA and PCL-PCA methods are useful on MRI for diagnosing partial ACL tears. PCLA value between 113°-123° and PCL-PCA value between 16°-24° could indicate a partial ACL tear. With these methods, it is possible to distinguish partial tears from healthy knees and reduce missed diagnoses. In addition, the differentiation of partial and complete tears by these methods may prevent unnecessary surgical interventions. LEVEL OF EVIDENCE: Level III.

Discoid Double-layered Lateral Meniscus: A Case Report.

Introduction: Abnormalities of the double-layered meniscus are rare and can be difficult to diagnose. The main pathology in this abnormality, which is predominantly seen in the lateral compartment, is an accessory meniscus lying over the normal meniscus. Anatomically, this structure can appear in different forms. Although other meniscal abnormalities associated with a double-layered meniscus have been reported, this case presents a previously undescribed type in the literature. Case Report: A 12-year-old girl presented to our clinic with complaints of knee locking and pain. When the patient underwent arthroscopy, an accessory incomplete discoid meniscus was found overlying the normal lateral meniscus. We performed an excision of the upper accessory meniscus and the patient had no problems during 3 years of follow-up after surgery. Conclusion: Abnormalities of the lateral meniscus are rare and can be difficult to diagnose. In cases where we suspect a meniscal abnormality, a proper arthroscopic examination should be performed and if a discoid meniscus is seen, it should be considered that this may be a double-layered meniscus.