What is a Synovial Impingement Posterolateral (SIPL) Lesion? SIPL lesions most commonly affect overhead athletes. SIPL lesions consist of a posterolateral impingement, or pinching of the synovial lining, within the joint capsule of the elbow. These lesions occur when a congenitally present synovial fold or a band of scar tissue exists inside the posterolateral aspect of the elbow that gets repetitively pinched with activity. Athletes often feel a clicking with a dull, aching pain after they exercise that gets worse with increasing duration of activity. Once it occurs, it does so repeatedly, causing very sharp pains initially and an aching sensation afterward. Eventually, the band of pinched tissue becomes swollen or larger and often more symptomatic. Causes Most commonly occurs in the overhead throwing athlete with increasing activity or overuse of the elbow without proper rest Changes in or poor mechanics at the elbow with activity Signs & Symptoms Pain in the posterolateral corner of the elbow Tenderness with deep palpation in the posterolateral elbow Clicking with repetitive flexion (bending) and extension (straightening) of the elbow Palpable band of tissue that recreates pain Treatment Treatment of SIPL lesions begins with elimination of the offending activities. If the elbow settles down quickly with rest, then a smooth return to activity is often quick. However, if the elbow does not easily become asymptomatic, an extended rest period is needed and more investigation is appropriate to be sure that an underlying more serious problem does not exist. Sometimes the use of diagnostic injections can help in the diagnosis and treatment and an MRI can often be an appropriate step. If the pain with exercise cannot be eliminated, arthroscopic evaluation and removal is recommended. For the overhead athlete, this as well as a structured interval throwing program will normally return an athlete to their previous level of performance relatively quickly.