special subjects
Work Related Repetitive Motion Injuries
Diagnosis
Clinical evaluation Sometimes nerve conduction studies or MRI Diagnosis of repetitive motion injury is primarily clinical based on the location of the pain and the movement that elicits pain; however, diagnostic testing is sometimes indicated. An occupational history is important to identify the nature of the repetitive motion that is causing the patient’s symptoms. Tendinitis is suspected when active movement of a tendon (particularly against resistance) causes pain. Tenderness when the tendon is palpated supports the diagnosis of tendinitis. Physicians can distinguish some severe cases of Cellulitis from tendinitis if skin induration is present; such induration, sometimes present in cellulitis, is absent in tendinitis. Site of Tendinitis Movement That Elicits Pain* Site of Tenderness During Palpation Biceps Flexion at elbow with forearm supinated Anterior aspect of shoulder Medial Epicondylitis (golfer’s elbow) Wrist flexion and forearm pronation At and just distal to medial epicondyle of the humerus Lateral Epicondylitis (tennis elbow) Wrist extension At and just distal to lateral epicondyle of the humerus Rotator Cuff Injury/Subacromial Bursitis None Shoulder abduction between 60–120° None *When resistance is applied. Bursitis is suspected when swelling or signs of inflammation over bursae are present or when patients have unexplained pain that is worsened by movements affecting bursae. Bursitis due to repetitive motions should be distinguished from infectious (septic) bursitis, which requires antibiotic therapy, and crystal-induced bursitis (eg, Gout ), which may require other specific treatments. When infectious or crystal-induced bursitis is suspected, synovial fluid should be aspirated and sent for laboratory analysis. Affected Bursa Location of Bursa Causative Repetitive Movement Ischial Between the ischial tuberosity and gluteus maximus Prolonged sitting on hard surface Olecranon Posterior to the proximal tip of the ulna Resting point of elbow on hard surface Prepatellar Anterior (superficial) to the patella Kneeling Subacromial Between the most lateral part of the supraspinatus tendon and the acromion Overhead arm movement Nerve entrapment syndromes are typically clinical, suspected when a worker presents with abnormal sensations along the territory of certain nerves. In some cases, nerve conduction studies may be useful in confirming the diagnosis but are not routinely required. Imaging is not typically done, but MRI may be done when a structural cause (eg, tumor) is suspected. Syndrome Nerve (location) Area of numbness Causative Repetitive Movement Carpal Tunnel Syndrome None Median (wrist) Lateral hand; thumb, index, and middle fingers and lateral half of the ring finger Wrist extension and flexion, vibration Cubital Tunnel Syndrome None Ulnar (elbow) Medial hand, little finger, medial ring finger Elbow flexion or leaning on the elbow 