“Challenges in the management of fractures in osteopetrosis”! Review of literature and technical tips learned from long-term management of seven patients
Introduction
Osteopetrosis is a group of sclerosing bone dysplasia characterised by diminished osteoclast mediated skeletal resorption.13 First described by Albert Schonberg in 1904,1 approximately 300 cases have been reported in the literature. However, few reports aid in the management of these patients.
Osteopetrosis has been categorised clinically into three primary types (Table 1): infantile, or “malignant” osteopetrosis, inherited in an autosomal recessive inheritance pattern; “intermediate” autosomal recessive osteopetrosis; and autosomal dominant osteopetrosis.16, 3
The incidence of autosomal recessive osteopetrosis is approximately 1 in 300,000 births but is almost 10 times as high in Costa Rica.9 In severe forms of osteopetrosis, the insufficient bone marrow cavity cannot support adequate haematopoiesis. This results in extra-medullary haematopoiesis, which causes hepatosplenomegaly. Children who are severely affected can have cranial-nerve dysfunction, and visual deficits are often evident at birth or within the first few months of life.12, 10 Thrombocytopenia, anaemia, and infectious complications commonly cause death within the first decade. In less severe forms, patients have a normal life expectancy, but the brittle bone frequently fractures, particularly in autosomal dominant osteopetrosis.4
Recently gene mutations,19 carbonic anhydrase II dysfunction,20 chloride channel abnormality6 have been implicated in the causation of various types of osteopetrosis. However, many as yet have no identifiable abnormal gene. Classifications based on molecular events and associated physiology will undoubtedly be more precise. It is logical to expect that there is a role for haematopoietic stem-cell transplantation in patients with intrinsic osteoclast defects and severe osteopetrosis.18 Further investigations will facilitate correlation of the various genotypes with the clinical presentation, anticipated complications, prognosis, and expected response to treatment.18
Adult orthopaedic presentations in osteopetrosis include periodic back pain, bone pain, recurrent fractures especially in lower limbs, degenerative arthritis and infections.2 Other common problems are due to compression of cranial nerves leading to blindness, hearing and vision loss and facial nerve palsy.2
Fractures in osteopetrosis can occur at any age. Because the healing response is variable, management must be adapted and individualised to address the technical challenges unique to this patient population. Operative intervention has a high rate of intra-operative and post-operative complications.
Seven patients treated in Hartlepool and North Tees Hospital over the last 10 years were included in the study. All patients’ notes were reviewed retrospectively. Five of these were diagnosed as intermediate autosomal recessive and other two as adult onset autosomal dominant type of inheritance. They presented frequently to the hospital with multiple problem fractures.
An account of their fractures and other orthopaedic problems is detailed in Table 2.
Section snippets
Results
All the fracture in cases 3, 4 and 6 were treated conservatively. Most of the fractures in other cases healed with conservative treatment. The surgical procedures were undertaken in some specific fractures. Details of individual procedure, problems seen during these surgeries and the measures used to tackle the difficulties encountered are illustrated in Table 3 and Fig. 1, Fig. 2, Fig. 3, Fig. 4.
Discussion
Osteopetrosis is a disease which results into universal failure of the bone remodeling process. The osteoclasts are functionally abnormal. There is insufficient resorption leading to excessive accumulation of bone matrix; causing hard, dense bones with loss of medullary canal.14
Bone growth is also abnormal resulting in short and broad or long and thin brittle bones.7 Fractures are often transverse and may result from minor trauma.7
We can only find isolated reports of the management of fractures
Conclusions
For most long bone fractures non-operative treatment works well. However, surgical management is reasonable in certain circumstances such as fracture neck and shaft of femur, Coxa Vara and failure of conservative treatment. Surgery can be prolonged and difficult. Good preoperative planning should anticipate the forthcoming technical difficulties. The prolonged intra-operative and post-operative course and risk of infection should be included in the informed consent.
Conflict of interest
There are no identifiable illustrations in the article; it is not in conflict with any previously published material and does not affect the personal or financial interest of any one.
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