Transient osteoporosis of the hip treated with hyperbaric oxygen therapy: a case series

Transient osteoporosis of the hip (TOH) is a self-limiting disorder characterized by bone marrow edema at the femoral head and neck. Patients report pain as moderate or severe at onset; pain gradually subsides at about six months (range four to 12 months). Differential diagnosis of the early stages of osteonecrosis of the femoral head (ONFH) is sometimes difficult. Because hyperbaric oxygen (HBO₂) therapy is effective for reduction of edema in soft tissue injury and early stages of ONFH, we hypothesized that HBO₂ could be effective in TOH for accelerated recovery.

Five cases of TOH treated with HBO₂ were clinically evaluated. HBO₂ was started from three to eight weeks after onset and performed four or five times a week, averaging a total of 27.8 ± 4.7 treatments (range 20-32). Clinical features were evaluated repeatedly with clinical examination, subjective evaluation of pain, and imaging methods that included magnetic resonance imaging (MRI) and bone scans.

The average time to return-to-normal hip range of motion was 15.4 ± 7.8 weeks after onset, and relief of subjective pain was 16.6 ± 4.0 weeks. The average time to return-to-normal signal level in MRI was 22.0 ± 2.5 weeks, which was one to two months after relief of subjective pain.

Multiple HBO₂ treatments have the possibility of contributing to recovery acceleration in patients with TOH. However, in this study, we found that HBO₂ treatment did not significantly accelerate the recovery of these five patients with TOH. The use of HBO₂ should therefore be limited to patients in whom the differential diagnosis between TOH and early stage ONFH cannot be established.