Bilateral symmetrical stress fractures of femoral neck in HIV patient: case report and brief review of literature

Osseous changes in HIV positive patients receiving ART are three times greater than in normal individuals. These changes include osteopaenia/osteoporosis, stress fractures, fragility fractures and osteonecrosis. On an average, bone mineral density reduces by 2–6% in the first 2 years after commencement of antiretroviral therapy. High risk for stress fractures is observed in these patients. In present article, we report a case of bilateral femoral neck stress fractures in a known HIV patient.


Investigations
Radiograph of the pelvis AP ( Figure 1) performed demonstrated features of osteoporosis with partial loss of trabeculae in the proximal femur and visualised pelvic bones.
CT of pelvis and dorsolumbar spine (Figure 2) performed demonstrated linear thin fracture lines within the neck of both femurs (more prominent on the left side) and prominent vertical/primary trabeculae with thinned out horizontal/secondary trabeculae in vertebral bodies, loss of trabecular pattern, and thinning of the cortex suggestive of generalised osteoporosis with stress fractures in the neck of bilateral femur bones.
MRI of pelvis with bilateral hip joints demonstrated stress fractures in the bilateral femoral neck as hypointense signals on T 1 W images, T 2 W images and hyperintense signals on STIR with surrounding sclerosis and oedema (Figures 3 and 4).
Whole-body bone mineral densitometry (BMD) was performed by Dual energy X-ray absorptiometry (DXA) to assess the mineralisation status of bones ( Figure 5). BMD measured at L1-L4 level demonstrated severe osteoporotic changes with the T score value of −3.9 and Z score value of −3.8. At left femur neck level, T score value was −3.8 and z score value −3.5, at right femur neck level, T score was −3.7 and Z score was −3.4. At the level of radius, the T score was −3.3 and Z score was −3.2 (Table 1).

Diagnosis
Based on the history of the patient, clinical presentation and imaging findings, the final diagnosis of bilateral femoral neck stress fractures with severe osteoporosis was considered ( Figure 3).

TREATMENT AND FOLLOW-UP
Surgical intervention with further medical management and follow-up was advised. As the symptoms were more severe on the left side, surgical intervention by hip arthroplasty was performed, and the femur head was replaced with an Austin-Moore prosthesis. Further conservative management was advised for the right femur fracture. The post-operative period was uneventful. As part of medical management, the patient was advised alendronate sodium

SUMMARY:
Osseous changes in HIV positive patients receiving ART are three times greater than in normal individuals. These changes include osteopaenia/osteoporosis, stress fractures, fragility fractures and osteonecrosis. On an average, bone mineral density reduces by 2-6% in the first 2 years after commencement of antiretroviral therapy. High risk for stress fractures is observed in these patients. In present article, we report a case of bilateral femoral neck stress fractures in a known HIV patient. BJR|case reports Narra et al tablets (35 mg) once monthly, vitamin D3 (60,000 IU) tablets once weekly. He was discharged and was advised for regular follow-up ( Figure 4).

DISCUSSION
High prevalence of decreased BMD has been reported in HIV patients. The exact cause of bone loss in HIV-infected patients was not completely established.
However, multiple factors including generalised physiological decrease in bone turnover, protease inhibitors, nucleosiderelated mitochondrial toxicity, lactic acid accumulation, HIVrelated lipodystrophy, immune reconstitution, nutritional and hormonal factors, prior AIDS-related wasting, and the damage by the virus itself are implicated as the potential causative factors. 1,2 Although the use of HAART has dramatically reduced the morbidity and mortality rates from HIV infection, long-term use of HAART results in multiple metabolic disorders including osteopaenia/osteoporosis. Among the drugs used in HAART, protease inhibitors have high potential for causing osteoporosis/osteopaenia. 3 On review of literature, many studies describing high prevalence of osteopaenia and osteoporosis in HIV patients on HAART regimen were reported ( Table 2).
Although HIV patients are at high risk for stress fractures due to osteoporosis, diagnosis of these fractures are often missed or delayed for several weeks due to lack of symptoms and absence of prior traumatic history. Further incomplete femoral neck stress fractures are often difficult to diagnose on plain radiographs. On review of literature, very few case reports describing bilateral sequential neck fractures of femoral neck have been reported. Chaganty et al 8    Although radiography is the first line of imaging modality, it seldom demonstrates the fracture. MRI has higher sensitivity in evaluating early stress fractures. Lassus et al 9 reported radiographs to have a sensitivity of 15-30% for early-stage injuries and 30-70% for late-stage injuries, while MRI is considered to have a near 100% sensitivity at all stages. Although CT is not considered a first/second-line imaging modality, it may have a role where the MRI results are equivocal, owing to high specificity.

reported a bilateral
The estimation of BMD by DXA scan is used as a screening tool to determine osteoporosis/osteopaenia and increased risk for stress fractures.
Bone scintigraphy identifies insufficiency fractures and pseudofractures early in their course before they are evident on conventional imaging. Bone scintigraphy should be investigation of choice in cases of limb pain, to identify the risk of stress fractures even before their occurrence to prevent further complications. 10

CONCLUSION
HIV infection and ART are risk factors for osteopaenia and osteoporosis and subsequent increased risk of stress fractures. Hence, these patients are advised for regular screening and correction of osteopaenia/osteoporosis ().

LEARNING POINTS
• Osteopaenia/osteoporosis are frequently observed in HIV patients on HAART treatment, with increased risk of stress fractures. • BMD with DXA scan aids in assessment of osteopaenia/ osteoporosis.   Tebas Pet et al 50% of cases receiving protease inhibitors had osteopaenia or osteoporosis, compared with 23% of cases not receiving these antiviral drugs.
Cassetti et al 6 Bone mineral density decreases by 2-6% within the first two years after initiation of various ART regimens. 7 Significant bone loss from the spine and hip occurs during the first 1-2 years after the initiation of antiretroviral therapy.

Juliet Compston et al
ART, antiretroviral therapy; HAART, highly active antiretroviral therapy.