Picture Quiz
Case history
A 23 year old man was involved in a road traffic accident, resulting in multiple injuries. He also dislocated his right elbow, which was initially treated by closed reduction, but subsequently it had required open reduction, as the joint was unstable. In spite of regular active physiotherapy he developed stiffness and limitation of movement around the elbow joint, with a range of flexion of 80 to 100 degrees. Four weeks later he developed weakness and neurological deficit in the right hand.
Figure 1
Questions
- What abnormalities can be seen on looking at figure 1?
- What is the most likely diagnosis?
- What was the underlying cause in this case? -- figure 2.
- What is the appropriate treatment?
Figure 2: Elbow radiograph
Answers
- There is clawing of the hand with obvious wasting of the hypotheaner muscle and first interossous muscle. In addition there is a trophic skin change at the classical sensory distribution of ulnar nerve, on the little finger and half of the ring finger, and the corresponding palmar aspect of the hand
- Ulnar nerve entrapment neuropathy
- Heterotopic ossification around the elbow
- Patients at risk of heterotopic ossification can be treated prophylactically with indomethacin for six weeks. Diphosphonates and irradiation have also been useful in preventing the condition. But once it is developed it can be treated only by surgical excision after the ossification has matured, traditionally at six to 12 months from the time of injury. Release of the ulnar nerve compression is usually effective in providing functional recovery.
Discussion
Heterotopic ossification (myositis ossificans) is a frequent complication after injuries around the elbow and consists of abnormal bone and cartilage formation in the soft tissues adjacent to the joint. Histologically, endochondral ossification and membranous bone formation are both present, and resemble fracture callus. This can limit joint motion and progress to ankylosis in a small percentage of patients. Heterotopic ossification may also cause entrapment of the ulnar nerve resulting, as in this case, in ulnar nerve neuropathy. The ulnar nerve is most commonly involved because of its vulnerable position beneath the subcutaneous tissue and adjacent to bone in the cubital tunnel. With flexion, the cubital tunnel decreases in volume, increasing the pressure on the nerve.
Myositis ossificans can follow passive stretching of joints, so this must never be practised around the elbow. Risk factors include male gender, past history of having formed heterotopic ossification, ankylosing spondylitis, and diffuse idiopathic skeletal hyperostosis. Heterotopic bone formation can also occur at other sites, especially around the shoulder, hip, and knee. It is found particularly in patients suffering head and spinal cord injuries. Post-traumatic heterotopic ossification can follow muscle contusion and can be mistakenly diagnosed as an osteosarcoma.
Patients at risk for heterotopic ossification can be treated prophylactically with low dose irradiation (8 to 10 Gy) administered within the first three to four days after operation. This obliterates the cellular proliferative response. Indomethacin treatment for six weeks after the operation significantly decreases the incidence of heterotopic bone formation. Ankylosis of joints secondary to heterotopic ossification can be treated by surgical excision after the ossification has matured, as early excision of the mass gives bad results, being almost always followed by massive recurrence. The alkaline phosphatase level, radiographic appearance, and technetium-99m bone scan activity assess the maturity of ectopic bone.
Late excision, say after six to 12 months, is often successful in removing the mechanical obstruction to movement with less risk of recurrence. Surgery is also effective to relieve compression of neurovascular structures. For entrapment ulnar neuropathy, release of ulnar nerve with or without anterior transposition has an effective result.
Kawan Shalli, senior house officer in general surgery, Monklands General Hospital, Lanarkshire
Email: kshalli@hotmail.com
studentBMJ 2001;09:261-304 August ISSN 0966-6494
