Approach Considerations
Surgical treatment of fibrous dysplasia is indicated in the prevention or treatment of fractures or major deformity. [30] The most common surgical indications are fracture of a weightbearing bone and progressive disease. Asymptomatic patients do not need treatment. A needle biopsy can be performed if there is doubt about the diagnosis before the initial management. Upper-extremity lesions rarely require surgical management. Nevertheless, vascularized bone grafting has been proposed. [31] Surgical management can be effective for both syndromic and nonsyndromic craniofacial fibrous dysplasia. [32]
There are no specific contraindications for surgical intervention in patients with fibrous dysplasia. However, care must be used in the skeletally immature patient. Internal fixation of long bones with intramedullary nails may be proposed.
In the future, effective nonsurgical treatments may be possible. Because the risk of local recurrence is high, the decision to treat must be made with informed consent to avoid inappropriate expectations. In general, the goals of surgery should be to stabilize the bone and relieve pain, rather than to excise the involved bone. The condition often is found incidentally, and the need for prophylactic treatment may be difficult to accept for an asymptomatic or minimally symptomatic patient.
Medical Therapy
Although there is no specific medical therapy for fibrous dysplasia, studies have shown decreased pain after treatment with bisphosphonates, which inhibit bone resorption by virtue of their action on osteoclasts. [33, 22, 34, 35]
The most common drug therapy is intravenous (IV) pamidronate. An IV infusion of pamidronate (total dose of 1 mg/kg/day over 3 days, repeated every 3-6 months) has been proposed. The total dose must be administered over a 4-hour period. Vitamin D and calcium supplements must be added to the regimen. This therapy in children seems to be safe, but longer follow-up is needed to confirm the absence of collateral effects on the growth plate. An increased growth-plate thickness has been reported in children treated with bisphosphonates. [10]
The PROFIDYS study (Oral Bisphosphonate Effect on Osseous Symptoms in Fibrous Dysplasia of Bone), a double-blind study evaluating the long-term safety and results of treatment with an oral bisphosphonate (risedronate), was initiated in 2007 with the aim of evaluating bone pain and the evolution of osteolytic lesions in patients with fibrous dysplasia.
Majoor et al evaluated the biochemical (bone turnover markers [BTMs]) and clinical (pain reduction) outcome of bisphosphonate therapy in 11 patients with McCune-Albright syndrome and 30 patients with polyostotic fibrous dysplasia who were treated for a median of 6 years (range, 2-25 y). [36] Their data suggested that long-term bisphosphonate therapy was beneficial and safe in the majority of patients with polyostotic fibrous dysplasia. The only prognostic factor found to influence the outcome of bisphosphonate therapy was a high skeletal burden score.
Wang et al retrospectively studied laboratory and clinical findings in 22 cases of polyostotic fibrous dysplasia associated with McCune-Albright syndrome, with the aims of (1) evaluating the efficacy and safety of bisphosphonate therapy and (2) comparing the efficacy of different bisphosphonates (ie, pamidronate and zoledronic acid) in this setting. [37] They found bisphosphonate treatment to be safe and well tolerated and to cause no obvious impairment in patients' linear growth. Zoledronic acid was similar to pamidronate in terms of controlling disease activity.
Denosumab has shown potential for treatment of fibrous dysplasia. [38, 39]
Surgical Therapy
If surgical treatment is required for fibrous dysplasia in long bones, intramedullary nailing is recommended. [40] This technique provides good stabilization and could prevent deformation. In younger children, nailing may have to be repeated to maintain stabilization during growth. [41]
Conservative treatment, use of plates, curettage, and bone grafting have generally been discouraged. [12, 17, 42] Deformity-correction surgery [43] is indicated in patients with mechanical axis deviation of the lower limbs.
A small study from Canada that included nine patients (10 hips) who underwent total hip arthroplasty (THA) for fibrous dysplasia found that, contrary to previous reports, low complication and revision rates were observed with cementless components and routine use of allograft material. [44]
The dysplastic bone in fibrous dysplasia can be quite difficult to ream. Fibrous dysplasia is associated with a high tendency of bone bleeding during surgery. [12]
Gui et al reported their experience with a navigation system they developed for use in conjunction with computer-aided recontouring in the surgical treatment of complex craniofacial fibrous dysplasia. [45] Surgical outcomes were assessed by superimposing postoperative computed tomography (CT) scans onto preoperative CT scans. The authors found that navigation-guided recontouring improved the accuracy and safety of the surgical treatment of complex craniofacial fibrous dysplasia.
Multiportal combined transorbital-transnasal endoscopic resection of fibrous dysplasia of the skull base and orbit has been described. [46]
Long-Term Monitoring
The main role of follow-up is to prevent deformity as a result of the disease. The authors recommend yearly radiographs of the involved area or areas until skeletal maturity. Because fibrous dysplasia rarely undergoes remission, it is appropriate to monitor disease progression periodically, especially in the skeletally immature patient. Once skeletal maturity has been achieved, it is unusual for monostotic fibrous dysplasia to progress.
Early intervention with internal fixation of involved bones may be important in the prevention of deformity. Referral to an endocrinologist for endocrine and metabolic testing is suggested so that endocrine anomalies can be diagnosed and treated.
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Intermediate-power view of typical histology of fibrous dysplasia. Note the bland fibrous stromal tissue with islands of disorganized, immature osteoid. A key feature is the absence of rimming osteoblasts around the osteoid. While not present in this slide, foci of cartilage also may occasionally be present.
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Plain radiograph of a tibia in a patient who is skeletally mature, demonstrating expansion of the metaphysis and diaphysis, endosteal scalloping, and a ground-glass appearance of the matrix.
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Technetium-99m methylene diphosphonate (MDP) bone scan demonstrating increased uptake in the tibia corresponding to the radiographic margins.
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CT scan of the tibia demonstrating expansion of the tibia due to an expanding intramedullary lesion.
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A T1-weighted MRI image demonstrating intermediate signal intensity and no soft tissue component.
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A T2-weighted MRI image demonstrating increased signal intensity of the matrix of the lesion.
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The metaplastic bone formed by fibrous dysplasia has the appearance of Chinese letters.
