Frequency of posterior interosseous nerve syndrome and its impact on clinical outcomes in patients with lateral epicondylitis: A prospective, controlled, electrophysiological study.

Introduction: Lateral epicondylitis (LE) is a musculoskeletal disorder characterized by pain around the lateral epicondyle. Posterior interosseous nerve syndrome (PINS), a rare neuropathy caused by radial nerve compression, can mimic or coexist with LE, complicating diagnosis. This study aimed to evaluate the electrophysiological presence of PINS in LE and determine its impact on symptoms.

Methods: This prospective study included 62 patients diagnosed with LE and 54 healthy controls. Electrophysiological examinations were performed on all patients in the LE group to investigate the presence of PINS. Subsequently, PINS-positive and PINS-negative patients within the LE group underwent a detailed clinical evaluation, including provocative tests, joint range of motion (ROM), hand grip strength, and symptom scoring using the Visual Analog Scale (VAS) and Patient-Rated Tennis Elbow Evaluation (PRTEE).

Results: PINS was identified in 19.4% of LE patients and 1.9% of controls (p < 0.05). There were no significant differences between PINS-positive and PINS-negative patients in the LE group regarding provocative tests, joint ROM, grip strength, VAS, or PRTEE scores. The diagnosis of PINS was made solely based on electrophysiological findings.

Discussion: This study highlights the importance of electrophysiological evaluation in the differential diagnosis of PINS and LE, especially in treatment-resistant cases. Although PINS did not significantly impact clinical parameters such as grip strength or symptom scores, its notable prevalence in LE patients underscores the need for its consideration in refractory LE cases. Further large-scale, controlled studies are needed to explore this relationship comprehensively.