In January 2017, a 22-year-old unmarried female presented with pain and swelling over the left forearm along the medial border of the forearm from the previous 8 days. She first experienced the swelling and deformity about 5 years before, but it was ignored because it was asymptomatic and did not interfere with the joint range of motion. The problem was only cosmetic. She could remember no severe trauma to the elbow joint, but minor injuries occurred in the routine work of a housewife. The pain was along the medial border of the forearm more on the mid half between wrist and elbow joints. She was afebrile and vital signs were stable. On examination there were two lumps, one lump at the mid of the forearm about 8×8 cm with visible deformity and another lump near the elbow joint which was 3×3 cm. There was mild tenderness along the medial border of the elbow up to mid forearm, range of motion at the elbow was normal, no palpable axillary lymph node and distal neurovascular were intact. Systemic examinations were normal. Routine tests like complete blood count, C-reactive protein and erythrocyte sedimentation rate were normal. Radiographs including anteroposterior and lateral views of the both elbow joints with forearms up to the wrists were done for comparison. X rays showed an accessory ulna articulating with the elbow joint without interfering with normal articulating joints at the elbow, extending up to the mid half of the forearm without articulating at the wrist joint. A diagnosis of accessory ulna was made. She was admitted and after a preoperative workup, surgical excision of the ulna was done. The patient was discharged on antibiotics and non-steroidal anti-inflammatory drugs. The patient was regularly followed for 2 months. Her pain was relieved and on examination there was no tenderness on palpation and the elbow had a normal range of motion. The preoperative image, preoperative and postoperative x-rays and intraoperative image are shown (Figures 1–4).
Figure 1
Anterior view of left forearm. The visible deformity and swellings at the mid of right forearm and near the elbow joint along the ulnar aspect. There is no discoloration of skin, no wasting of muscles and only small visible veins.
Figure 2
Anterioposterior and lateral views of the right elbow joint. The right elbow has another bone outside the elbow joint that does not extend to the elbow joint. It articulates with the humerus through another small joint.
Figure 3
Anteroposterior and lateral views of the right elbow joint. There is no accessory bone. It had been successfully excised without interfering with the normal joint.
Figure 4
Intraoperative image of accessory ulna after excision.
Accessory bones are also called ossicles and are considered normal variants of anatomic bones.1 Accessory ossicles may be found anywhere on the body, but most commonly in the foot. Accessory navicular bones are the most common accessory bone in the foot, occurring in up to about 20% of the population, and are frequently bilateral.2 An accessory ulna is extremely rare. The elbow joint is a complex joint made up of the humerus, radius and ulna.3 They form three different joints—the radiohumeral joint, the ulnohumeral joint, and the proximal radioulnar joint.4 To the best of our knowledge, this is the first documented case of accessory ulna causing local tenderness, and deformity without neurologic involvement. It was successfully managed with excision. Accessory bones are usually found incidentally on imaging studies for other bones or occasionally when these bones become painful after trauma, degenerative changes, or necrotic due to decreased blood supply and when they impact the adjacent soft tissues after increasing in size.5
Figure 1
Figure 2
Figure 3
Figure 4