Transient osteoporosis of the hip, idiopathic, is a table, beginning with hip pain without a history of trauma, usually self-limiting and seen in middle-aged men and pregnant women. In this case report, a male patient who was admitted because of hip pain and detected transient osteoporosis go the hip was discussed. The purpose of the case presentation is to emphasize the necessity of transient osteoporosis of the hip in the differential diagnosis of sudden onset of hip pain and to review the literature on this subject.

BACKGROUND: Transient osteoporosis of the hip (TOH) is a rare and temporary clinical condition characterised by bone marrow edema (BME), severe pain, and functional limitation. It commonly occurs in middle-aged men or in women in the last trimester of pregnancy. TOH usually resolves with conservative therapy but may predispose to hip fracture or progression to avascular necrosis (AVN). Etiology is still unclear, although several pathophysiological mechanisms underpinning this condition has been proposed. We describe the management of an unusual case of TOH occurred in a patient with subclinical hypothyroidism.
METHODS: A clinical case of a 46-year-old man with severe pain in the left anterior thigh is presented. After a comprehensive clinical and radiological approach, a TOH was diagnosed. Moreover, biochemical assessment suggested the presence of subclinical hypothyroidism. After 3 months of treatment with clodronate, physical therapy and hormone replacement therapy (HRT) a significant improvement of clinical and radiological outcomes was observed.
CONCLUSIONS: Several pathological conditions have been related to development of TOH. In our case, we suggested for the first time a role of subclinical hypothyroidism as novel contributory factor for the onset of this condition, providing pathophysiological mechanisms and a scientific rationale for pharmacological treatment.

BACKGROUND: 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.
METHODS: 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.
RESULTS: 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.
UNASSIGNED: 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.

We describe a case of non-simultaneous bilateral hip pain with bone marrow edema occurring in an adult male, with the contralateral hip being involved 12 years later after the onset of symptoms. On the basis of clinical and imaging findings, together with a complete resolution after conservative management, a post-hoc diagnosis of metachronous bilateral transient osteoporosis of the hip (TOH) was made. Non-simultaneous bilateral presentation of TOH is exceptional, and contralateral involvement with a 12-year delay has never been previously described.

Transient osteoporosis of the hip (TOH) is a benign, selflimiting condition characterised by acute onset groin pain in adults. Early diagnosis is important to differentiate it from progressive conditions such as osteonecrosis. We report on a middle-aged male who presented with right groin pain without any prior trauma. The diagnosis of transient osteoporosis of hip was confirmed by Magnetic Resonance Imaging (MRI) and he was successfully treated with a course of Alendronate sodium, anti-inflammatory analgesics and a period of non-weight bearing ambulation.