Soft Tissue/Bony Adaptation in Throwing Elbow

It is known that our body has an ability to adapt in response to stress placed on it. Muscles get bigger and stronger after weight lifting. Endurance improves after prolonged exercise. In similar way, properties of joints and soft tissues changes as a result of stress placed on them. For example, in overhead athletes, they will lose the amount of internal rotation range of motion (ROM) and gain external rotation ROM, commonly known as GIRD (glenohumeral internal rotation deficits). In throwing elbow, as a result of repetitive throwing motion, soft tissue and bony adaptation about the elbow joint occurs. During throwing motion, distractive force is placed on the medial side (inside) of the elbow, where ulnar collateral ligament is. Compressive force exists on the lateral side (outside) of the joint. Also, stress is placed between trochlea and olecranon on the back of the elbow joint. After repetitive stress placed on the joint, it is shown that properties of UCL may change without any symptoms. In a study conducted on non-injured high school-aged baseball pitchers, MRI's were taken on their throwing elbows and non-throwing elbows and those images were compared. They found out that more than 60% of pitchers had thickening of the ligament in throwing elbow. Also, they found sclerosis in ulnar-throchlea joint without symptoms. Sclerosis means hardening of a bone mainly as a result of repetitive direct contact between two bones. We do not know it this will be a risk factor for future injuries or this may indicate anything significant. However, even in healthy pitchers, these changes do occur. When evaluating throwing athletes, it is important to know that these changes in MRI may not indicate an actual injuries if it is not consistent with objective and subjective evaluation. Other findings in the study was edema around UCL attachment, bone spur, etc. Further studies will be needed to investigate whether this soft tissue and bony adaptation may indicate risks of future injuries.  

MRI image of UCL tear