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A relatively common cause of pain in the hand

Rob Powers, PA-C, ATC

Rob Powers is a PA in orthopedic surgery at Mattern & Associates, Dover, Delaware. He has indicated no relationships to disclose relating to the content of this article.

CASE

A 22-year-old teacher presented to our clinic with a complaint of right hand pain while pulling a zipper attached to her boots. She stated that while trying to zip her boot, she experienced pain along the top of her right hand below her first finger. She denied any traumatic injury to her hand. However, while zipping her boot, she felt a “pop” and heard a “snap” along her hand that produced significant pain and discomfort. She treated the symptoms with ice, naproxen (Aleve), and acetaminophen (Tylenol), which did not provide any significant relief. Physical examination revealed mild swelling and tenderness to palpation along the second metacarpal. There was no crepitus, deformity, or rotation. Neurovascular status was normal throughout the hand. Three-view plain films were ordered and enabled us to make a diagnosis (see Figure 1). What does this radiograph reveal?

DISCUSSION

Figure 1 demonstrates a nondisplaced fracture of the second metacarpal associated with an enchondroma, which is a benign intramedullary cartilage bone tumor. Most often, enchondromas are asymptomatic until a traumatic event produces a pathologic fracture, with subsequent onset of pain or dysfunction.

Enchondromas are one of the most common osseous tumors of the hand. Although typically not malignant, some forms of the condition are associated with malignancy. Enchondromas of the hand are generally found in the metacarpals and the proximal and middle phalanges and usually develop in persons aged 10 to 60 years. Males and females are affected equally.

An enchondroma appears on plain film as a symmetric fusiform expansion that is lucent and can have intermittent calcifications. Typically, enchondromas are found in the diaphysis or metaphysis of bones and rarely in the epiphysis. Associated conditions include Ollier’s disease and Maffucci’s syndrome. Ollier’s disease manifests with multiple enchondromas, described as multiple enchondromatosis, and has a concomitant malignancy risk of about 30%. Maffucci’s syndrome manifests with multiple hemangiomas as well as enchondromas. This condition has a 100% malignancy rate.

The concern with our patient was not malignancy, because she had only one enchondroma, but rather the size of the enchondroma and the fracture. Figure 2 demonstrates how the enchondroma is visible from the diaphysis to the metaphysis, and to the medial and lateral cortices, but not into the epiphysis of the second metacarpal. The radiograph also shows how very thin and susceptible to fracture the cortex is. The fracture is clear on plain films, as it is a nondisplaced fracture that very easily could become displaced. This fracture needed to be stable before treatment for the enchondroma could be initiated.

Initial treatment consisted of placing the patient into a finger spica cast for 1 month. At the end of the month, she returned to the office for examination and new plain films, which demonstrated callus formation at the site of the fracture as well as spotty calcifications throughout the enchondroma. Except for the healing fracture, the enchondroma’s appearance had not changed; the cortices remained very thin and susceptible to refracture. There was less tenderness at the region of the fracture. A plan for surgery was discussed with the patient. She agreed to the procedure and was placed in a new cast to protect her hand from new injury.

The surgical procedure required curettage and bone grafting of the enchondroma. A bone window was made along the diaphysis of the second metacarpal. As an example, Figure 3 shows a bone window in a proximal femur enchondroma in another patient, allowing for curettage of the lesion. A similar approach was taken for our patient’s hand enchondroma. A curette was used to remove the cartilaginous material from the bone, taking care not to fracture the metacarpal. Once the enchondroma had been satisfactorily curetted, the bone material was sent to pathology for analysis for malignancy, with a description for the pathologist of the location and source of the specimen.

Next, bone grafting was performed. Cancellous allograft bone chips were inserted into the hollow defect of the second metacarpal to provide bone structure to the enchondroma. An autograft source can be used, but this requires a second procedure to harvest the bone, usually from the iliac crest of the hip. This process can be somewhat painful to patients and thus add to the current problem. Once the enchondroma is sufficiently packed with allograft bone chips, the bone window can be closed with the removed bone fragment or closed over with the overlying soft tissue.

Typically, some form of internal fixation is performed. Internal fixation of the femoral enchondroma shown in Figure 3 was done with an intramedullary nail, which provided immediate stability for the femoral lesion. For a hand lesion, however, a small, semitubular fracture plate or some other similar device would be used. This will provide immediate stability to the metacarpal, preventing any accidental fracture. Once the internal fixation device is in place, the wound is closed, the hand is placed in a soft cast, and the patient is monitored during follow-up office visits for postoperative care, including plain films.

Enchondromas not in the hand usually require simple observation if they present no risk for fracture. Serial plain films of the lesions at 3 months, 6 months, and 1 year after diagnosis help to monitor any possible change to the lesion. MRI can also be helpful and can allay any fears a patient may have about malignancy. A 3% risk exists that a simple benign enchondroma may become malignant in the future. Therefore, these lesions require continued observation. Lesions that are at risk for pathologic fracture require treatment as described above. The femoral enchondroma mentioned earlier was found incidentally on abdominal CT done for a complaint of abdominal pain. If that lesion had not been found, most likely the patient would have suffered a fractured hip and required a bipolar hip replacement. Had our patient not injured her hand, at some future time her metacarpal would have fractured, leading to the discovery of the enchondroma. Observation and appropriate management of an enchondroma results in a successful outcome for the patient and clinician. JAAPA

Julie Vajnar, PA-C, RT, department editor