The radiohumeral synovial plica: anatomy, histology, and implications in chronic lateral epicondylitis.

Objectives: Our study aimed to elucidate synovial plica (SP) of the elbow histological characteristics and the anatomical relationship with adjacent structures. Subsequently, we sought to assess the relationship between SP and clinical symptoms as well as magnetic resonance imaging (MRI) features in patients with chronic lateral epicondylitis.

Methods: MRI was performed on eight cadaveric elbows specimens. The MRI findings were compared with those in anatomic sections and histologic preparations. In addition, ninety-nine patients with chronic lateral epicondylitis who underwent preoperative elbow MRI and arthroscopic surgery were included. The patients were divided into SP and without SP groups. The differences in clinical symptoms and MRI features between the two groups were compared.

Results: SP is located proximal to the annular ligament that extends into the joint cavity, then moves to the lateral collateral ligament (LCL) complex, and finally attaches to the lateral epicondyle of the elbow along with the common extensor tendon (CET). The SP, ligament, and tendon blend imperceptibly without distinct boundaries. Furthermore, in a study of patients with chronic lateral epicondylitis, we found that compared to the without SP group, patients in the SP group had higher preoperative and 3-week postoperative VAS scores and more severe abnormalities in LCL complex and CET.

Conclusion: The SP is distinct from the annular ligament and closely correlates with the LCL complex and CET enthesis at the lateral epicondyle. Chronic lateral epicondylitis patients with SP have more severe abnormalities of the LCL complex and CET, more severe pain, and longer postoperative recovery times.

Key points: Question Synovial plica (SP) cause lateral elbow pain, but few studies regarding histological and imaging features of SP and its relationship to chronic lateral epicondylitis exist. Findings The presence of SP leads to more severe common extensor tendon abnormalities and higher visual analog scale scores in patients with chronic lateral epicondylitis. Clinical relevance The combination of magnetic resonance imaging and clinical symptoms to further understand the effect of SP on the clinical symptoms and postoperative recovery in chronic lateral epicondylitis can help refine treatment strategies and improve the prognosis of patients.