Knee melorheostosis treated by drilling fenestration: a case report.

Melorheostosis, a rare sclerosing bone dysplasia, was first described by Leri and Joanny1. The name which is derived from the Greek words melos (limb) and rheos (flow), refers to the characteristic radiographic appearance of the sclerosing bone changes, which resemble candle wax dripping down the bone. This condition may be present at birth but more commonly develops in late childhood. It is typically characterized by abnormalities of the skeleton and adjacent soft tissues and affects mainly the diaphyses of long bones, the bones of the hands and feet, the pelvis and, rarely, the vertebrae and ribs. It usually affects one side of body or is limited to a single limb in which several bones may be affected. The diagnosis is made by conventional radiography and bone scintigraphy. Advanced imaging techniques such as MRI are rarely necessary for evaluation of this disease, mostly being performed to evaluate concomitant soft-tissue masses. A 21 year-old girl presented with a 2 year history of severe pain in her right knee. She initially had intermittent dull pain that had progressed rapidly. There was no history of trauma and she had no other complaints. Examination revealed a slight arthrocele of the right knee, a negative floating patella test, and no soft-tissue masses. The right knee could be flexed to 100° and extension was 10° short of full. There were no other notable abnormalities of the limb. Radiographic investigation demonstrated the typical “candle-wax dripping” pattern of melorheostosis. Radiographs of the entire skeleton were taken and sclerosing lesions found to be affecting the whole right lower limb (Figs. 1a–e). There was no evidence of additional lesions in other parts of the body. The surgical intervention of decompression by drilling fenestration of the right patella was performed (Fig. 1f). A Ø3.5 mm bone burr was drilled through the abscissa axis of patella. Following this surgical intervention the patient's severe pain had disappeared and her arthrocele had reduced. Clinical follow-up 6 months later showed her to be free of pain and of the previously noted arthrocele. (A–E) Typical “candle-wax dripping” pattern and endosteal sclerosing lesions were found to affect the whole right lower limb). (F) The surgical intervention of decompression by drilling fenestration of the right patella was performed. Melorheostosis is a rare, benign disorder that mainly affects bone. The onset of the condition is usually insidious. The symptoms, which include deformity of the involved extremity, pain, limb stiffness, and limitation of motion in the joints, do not manifest until late childhood or early adolescence and tend to progress into adult life. The disease exhibits a slow, chronic course, with periods of exacerbation and remission2. One or several bones may be affected; they are usually limited to one limb and unilateral. The lower extremity is much more commonly affected. Because the abnormal ossification frequently involves the soft tissues and extend into the joints, the latter often have a restricted range of motion as the result of contractures and fibrosis3-7. Radiologically, the lesions appear as clearly defined sclerotic densities that are mainly cortical, but also extend into the medullary portion of the affected bones, and have a linear pattern of distribution along the long axis of the limb. The appearance of this type of hyperostosis has been likened to candle-wax flowing down the margins of affected bones. The diagnosis of melorheostosis is made radiographically by demonstrating the classical endosteal or periosteal sclerosing lesions. There is no specific treatment for melorheostosis. The treatment of melorheostosis should be individualized based on the patient's lifestyle, progression of disease and age. Generally, emphasis is placed on conservative measures. In more severe cases surgery may be required. Surgical treatment consists of soft-tissue procedures such as tendon lengthening, excision of fibrous and osseous tissue, fasciotomy, and capsulotomy. Other procedures include corrective osteotomies, excision of hyperostotic bone, and even amputation of severely affected and painful limbs with vascular ischemia. Recurrences are common. In our case, severe pain of the right knee had not been controlled by non-steroidal anti-inflammatory drugs and physiotherapy. We believed that the main reason for her severe pain was increased tension in the patella. Given the patient's condition, we performed the surgical intervention of decompression by drilling fenestration of the right patella. Following surgical intervention her dramatic pain had disappeared and the arthrocele had reduced. Clinical follow-up 6 months later showed her to be free of pain and the previously diagnosed arthrocele. We suggest that severe knee pain caused by melorheostosis can respond favorably to decompression surgery.