An Unusual Cause of Medial Arm Pain
James R. Clugston, MD, MS; Sheryl H. Heinicka, MSN, BC; Joan M. Street, RT(R)(QM)
THE PHYSICIAN AND SPORTSMEDICINE - VOL 32 - NO. 1 - JANUARY 2021
A 21-year-old woman came to the student health facility reporting left medial arm pain. The pain had occurred intermittently over the last year after strenuous upper-body weight lifting, especially biceps curls. She had recently noticed a bump on the inside of her left arm at the site of pain. The bump was present continuously despite the intermittent nature of her pain. No numbness, tingling, or loss of arm strength were noted, and she did not have neck, shoulder, elbow, or wrist pain, or similar symptoms in the opposite arm. The patient had no history of fractures, other bone abnormalities, or trauma to this area. She was not currently taking medication and was not using supplements.
Examination revealed a firm nodular prominence approximately 4 to 5 cm proximal to the medial epicondyle of the left humerus, but no corresponding prominence on her contralateral arm. The nodule was immobile and tender to palpation. The overlying skin had no erythema, edema, or warmth, and was nonadherent. Palpation of the nodule and surrounding tissues did not produce paresthesia. She had normal sensation, strength, and pulses in both arms, and her shoulder, elbow, and wrist range of motion were normal. Her axillary and epitrochlear lymph nodes were nonpalpable. Anteroposterior (AP) and lateral radiographs were obtained (figure 1).
What is your diagnosis? What conditions should be included in the differential diagnosis?
Plain radiographs demonstrated a supracondylar process of the humerus. It appears as a bony hooklike projection extending from the distal anteromedial humerus approximately 4 to 5 cm from the medial epicondyle (figure 2) and projects anteriorly and inferiorly toward the medial epicondyle.
Our differential diagnosis also included bony exostosis (osteochondroma), heterotopic bone formation (myositis ossificans), and the appearance of the x-ray technologist's distal phalanx (thumb). The original radiology report called this a bony exostosis.
Because we saw no signs of nerve impingement, the patient was treated conservatively. She avoided painful activities, continued elbow mobilization, and used nonsteroidal anti-inflammatory drugs (NSAIDs) for pain as necessary. She made a very gradual return to her normal activities but has been lost to long-term follow-up.
A supracondylar process of the humerus is a congenital variation of the distal humerus.1 First described by Sir John Struthers in 1854,2 this vestigial structure is present in 0.3% to 2.7% of people.1-3 Humeral supracondylar processes are described as normal variants in many radiographic texts.
Frequently, a fibrous structure called the ligament of Struthers (figure 3) extends from the bony distal tip of the process to the medial epicondyle of the humerus. Lower fibers of the coracobrachialis muscle and upper fibers of the pronator teres muscle often arise from either the supracondylar process or the ligament of Struthers.1 The process and ligament may occasionally entrap the median nerve and/or brachial artery that travel between these structures and the medial border of the humerus and medial epicondyle. Rarely, ulnar nerve entrapment has been reported when the fibrous band does not attach at the medial epicondyle but instead attaches and blends to a fibrous arch between the heads of the flexor carpi ulnaris muscle.2
Keats' description3 of a humeral supracondylar process matched our patient's exam and radiographic findings. The process protruded toward the elbow joint, and the underlying humeral cortex was intact and did not continue into the process. An osteochondroma would typically point away from the joint and share a continuous cortex with the underlying bone.2 Our patient's bony fragment clearly originated from the humerus and thus was not a heterotopic ossification center that would be seen in myositis ossificans. Close examination of the radiographs enabled us to differentiate the hooklike appendage from that of a distal phalanx of a radiographer who might have been positioning the patient at the time the exposure was taken.
Initial observations. Patients report pain at the site of the supracondylar process (as our patient did) or, less frequently, paresthesias and weakness that are caused by compression of the median nerve, brachial artery, or ulnar nerve.1-4 Fracture of the supracondylar process may occur from direct trauma to the medial humerus, and patients often have a palpable bony mass in the area.
Active extension with pronation and supination of the wrist may exacerbate pain, median nerve paresthesias, and brachial artery compression.1 This motion may strain either the pronator teres or coracobrachialis muscle attachments at the supracondylar process. Our patient identified general upper-extremity weight lifting, particularly bicep curls, as causing her medial arm pain. It is likely that these activities indirectly involved the pronator teres and coracobrachialis muscle attachments.
Diagnostic techniques. Diagnosis may be made clinically by palpation but usually requires radiographs for confirmation. AP and lateral views of the humerus, although adequate in this case, are not always sufficient. Because the supracondylar process projects from the anteromedial aspect of the distal humerus, oblique views are often needed to see the process' profile.1
Management. Treatment is conservative for patients who have only minor pain and no signs of brachial artery, median nerve, or ulnar nerve impingement, such as numbness, weakness, or tingling. Conservative measures include NSAIDs, rest, and protection of the area. In patients who have fractures of the supracondylar process but no brachial artery, median nerve, or ulnar nerve impingement, treatment is also conservative. Most of these fractures heal spontaneously with avoidance of painful activities, elbow mobilization, muscle strengthening, and occasional brief elbow immobilization, if needed for severe pain.1 If the supracondylar process or its fracture fragment remains painful or impinges the artery or nerves, surgical resection may be necessary.1,2
Dr Clugston is an assistant professor in the department of community health and family medicine at the University of Florida in Gainesville and holds a certificate of added qualifications in sports medicine. Ms Heinicka is a nurse practitioner and Ms Street is a radiologic technologist at the University of Florida Student Health Care Center. Address correspondence to James R. Clugston, MD, MS, University of Florida Student Health Care Center, Box 117500, Gainesville, FL 32611-7500; e-mail to [email protected].
Disclosure information: Dr Clugston, Ms Heinicka, and Ms Street disclose no significant relationship with any manufacturer of any commercial product mentioned in this article. No drug is mentioned in this article for an unlabeled use.