Transient Osteoporosis of the Hip: A Mysterious Cause of Hip Pain in Adults

Abstract

Background: Transient osteoporosis of the hip (TOH) is a poorly understood and forgotten clinical entity. The diagnosis is often delayed, and inappropriate treatment is provided, due to the lack of its awareness among the clinicians.

Materials and methods: Twelve patients (11 male and one female) within the age group of 35-50 years, were identified retrospectively from the hospital records between July 2011 and June 2015 who had evidence of TOH on clinical and radiological parameters.

Results: All the patients were treated conservatively by nonweight bearing mobilization, anti-inflammatory drugs, bisphosphonates, calcium, and Vitamin D supplements. None of our patients had any symptoms after 6 months of conservative management. The disease did not progress, and there was no evidence of hip joint involvement in any of the cases. Plain radiographs were not diagnostic in the early detection of TOH. Magnetic resonance imaging was found to be highly specific and sensitive in diagnosing TOH. The clinical condition of TOH is characterized by its acute onset of hip pain in middle-aged people, and its symptoms are out of proportion to the radiological findings.

Conclusion: The TOH is a nondestructive and self-limiting condition of the hip, which responds well to the conservative treatment. We believe that TOH could be a subset of complex regional pain syndrome type 1, as it has many similarities in clinical presentation and management. Awareness of this entity is important to the clinicians for an early diagnosis and to avoid unnecessary treatment for other mimicking conditions.

Keywords: Avascular necrosis; Osteoporosis; avascular necrosis of bone; magnetic resonance imaging; reflex sympathetic dystrophy; sudeck dystrophy; transient osteoporosis of the hip.

Figure 1

Short tau inversion recovery coronal image showing diffuse hyperintensity extending from the femoral head (right) to intertrochanteric region suggestive of bone marrow edema with mild joint effusion. No focal changes of osteonecrosis seen. Findings are typical of transient osteoporosis of the hip

Figure 2

Short tau inversion recovery coronal image showing edema in the form of hyperintensity involving head, neck, and adjacent intertrochanteric region of the left femur. Femoral and acetabular articular surfaces show maintained contour. Mild joint effusion is also seen

Figure 3

Short tau inversion recovery coronal image showing normal marrow signal intensity in the left hip with no evidence of edema on followup. No joint effusion is seen. There is no evidence of secondary arthritic changes/collapse of the femoral head