Transient osteoporosis of the hip in an old woman: a case report

¹Rheumatology Department, CHU Tanger-Tetouan-Al Hoceima, Faculty of Medicine and Pharmacy, Abdelmalek Essaadi University, Tangier, Morocco

^&Corresponding author
Anass Adnine, Rheumatology Department, CHU Tanger-Tetouan-Al Hoceima, Faculty of Medicine and Pharmacy, Abdelmalek Essaadi University, Tangier, Morocco

Introduction    

Transient Osteoporosis of the Hip (TOH) also referred to as Primary Bone Marrow Edema syndrome (BMES) is a mysterious self-limiting condition of the hip [1,2]. This condition spontaneously resolves in several weeks to months with or without treatment, and it´s often mistaken as avascular necrosis of the femur (AVN) [3]. The proper diagnosis is necessary to avoid invasive surgical intervention. Through a case of an old woman who was diagnosed with TOH we review the hallmarks of this condition.

Patient and observation     

Patient information: in last May, a 65-year-old woman was admitted to our outpatient clinic, she had a history of type 2 diabetes diagnosed 3 months ago under metformin. She had no other significant medical history and no predisposing factors for osteonecrosis.

Clinical findings and timeline: in the absence of a traumatic injury, the patient developed over the course of two months acute pain in the right groin, radiating down the right thigh. The pain worsened when she walked and partially relieved when she rested, by the time she consulted she couldn´t bear weight and walked with crutches. The pain score evaluation of the right groin was 8 out of 10 via visual analogue scale. She had no fever and no other rheumatologic sign. She didn´t complain of weight loss or asthenia. The patient temperature was 36.9 °C, she limped because of the pain in her right groin, monopodal support was impossible, the left hip was mobile with a normal range of motion, but the right hip was painfully limited (the following ranges of motion were obtained: flexion 35°, extension 15°, abduction 30°, adduction 25°, internal rotation 20° and external rotation 30°), Patrick test was positive and both anterior and posterior impingement tests were negative. The rest of the rheumatologic examination was unremarkable. And the general examination showed no anomaly.

Diagnostic assessment: laboratory examinations of blood revealed the following results: normal erythrocyte sedimentation rate (ESR): 21 mm/h, normal CRP 3.2 mg/l, a deficiency in 25-hydroxy-vitamin D: 18 μg/ml (normal > 30 μg/ml). Full blood counts, liver function, renal function, parathyroid hormone and bone metabolism tests were within normal limits. Anteroposterior X-rays of the pelvis and hips showed no anomaly. The Ultrasounds of hips showed synovial thickening without joint effusion at the right hip, and was normal at the left hip. Magnetic resonance imaging of the pelvis showed diffuse homogenous low intensity signal on T1 -weighted images and high intensity T2- weighted images of the right femoral head and neck which demonstrate a diffuse bone edema of the head and neck of the right femur, there was no sign of osteonecrosis or stress fracture of the subchondral bone. (Figure 1,Figure 2, Figure 3).

Diagnosis: the diagnosis of transient osteoporosis of the right hip was retained.

Therapeutic intervention: a conservative treatment was prescribed, we recommended rest to reduce the load on the femoral head. The use of a walking aid device was necessary. Physiotherapy was initiated to reduce pain. Tramadol 100 mg per day, intravenous zoledronic acid 5 mg, calcium and vitamin D were prescribed.

Follow-up and outcome of interventions: the patient was improved and pain free by the fourth week of treatment, and she could walk without crutches and up to 01 kilometers without pain or discomfort.

Patient perspective: the patient was very satisfied with this treatment.

Informed consent: this was obtained from the patient.

Discussion     

With less than 400 published cases, TOH is a rare, uncommon disorder. First described in 1959, Curtiss and Kincaid reported three cases of pregnant women who developed in the third trimester acute unilateral pain in the hip and thigh. Radiology showed spotty demineralization in the affected femoral head and neck, the patients recovered spontaneously several months after delivery [4]. Transient osteoporosis usually affects the hip, but in rare cases it can affect the knee, the ankle or the foot [5]. Transient osteoporosis of the hip usually affects one hip, but in rare cases it can be simultaneously bilateral [6]. Transient osteoporosis of the hip mainly affects middle-aged women with sex-ratio of 3/1. In women, it mostly occurs in the last trimester of pregnancy. Some publications report that it can also affect young men [6]. Our case demonstrate that TOH can also affect women in their sixties. Reported risk factors in the literature includes pregnancy, alcohol consumption, smoking, steroid usage, low testosterone, hypophosphatemia, low vitamin D, osteogenesis imperfect and certain occupations [2,7-9]. To this date the exact etiolopathogenic mechanism of TOH is unknown, multiple theories were proposed. It was suggested that TOH is due to vasomotor disturbances caused by sympathic nervous system dysfunction and therefore a subtype of complex regional pain syndrome [10-11]. other studies suggest the role of medullary hypertension due to obstructed venous return, particularly in the context of pregnancy [12]. Some studies mention an increased osteoclastic bone resorption in the hip caused by some viral infections [13]. Transient osteoporosis of the hip was initially thought to be an early stage of AVN, since early eighties, TOH was clearly distinguished [14]. Some recent studies suggest that Regional migratory osteoporosis (RMO) can be a progression of TOH [15,16]. Which led some authors to propose a common pathophysiology between the two entities [16]. In 2015, Klontzas et al. found out that 19.4% of TOH patients progressed to RMO [17].

Transient osteoporosis of the hip is a poorly known condition, the pain is more severe than osteonecrosis with a sudden onset. Clinically, it manifests as an acute pain in the groin region, sometimes in the buttocks and radiate to the anterior side of the thigh. The pain worsens at night and at the slightest activity. Examination is often disproportionate to the symptoms, with preservation of the range of movement. Rarely, there may be some limitation of abduction and rotation. During the evolution of TOH three phases can be distinguished. The initial phase lasts approximately six weeks, it is characterized by an acute pain with functional limitation of the affected limb. It is followed by a plateau phase that lasts for one or two months. During this stage, radiographs of the femoral head shows diffuse spotty osteopenia. The final phase usually lasts for four months, the clinical symptoms regress spontaneously, the bone density returns to normal. During the whole course of the disease, the joint space is preserved with no geode and no osseous erosion. Magnetic Resonance imaging (MRI) is the most suited Exam for detection of bone edema, with enough sensitivity to detect TOH as early as 48 hours after the onset of symptoms [2,18]. Magnetic Resonance imaging (MRI) findings that support TOH include intermediate signal sequences on T1-weighted images and high signal intensity on T2-weighted images. Another MRI finding is hyper intensity on contrast enhanced images. The delayed peak enhancement of edematous marrow is very characteristic of TOH. Although is rare, TOH can progress to AVN. Dunstan et al. reported some cases of TOH that progressed to AVN [19]. Treatment of TOH is conservative and includes rest, unloading of the affected hip, and analgesic medication. Antiresorptive agents including bisphosphonates have been reported to alleviate pain and accelerate clinical and radiological recovery. These considerations come from individual case reports and uncontrolled case series [3,16]. The rapid recovery in our patient (clinical recovery in third week) can be related to zoledronic acid perfusion. Any additional beneficial effect of antiresorptive therapy in such cases would be difficult to determine outside a clinical trial. So it seems reasonable to initially treat TOH conservatively, and reserve the use of bisphosphonates for those with severe pain or disability, and those at highest risk of fracture. Physiotherapy must be prescribed to prevent muscle atrophy.

Conclusion     

In summary, TOH is a rare disorder that should be considered in the etiological diagnosis of acute hip pain not only in young or middle-aged men and pregnant or postpartum women, but also in older women. It generally has a benign prognosis, with full recovery occurring within several months. The management of TOH is initially conservative. The role of antiresorptive agents is unclear, but it may be beneficial in those people whose symptoms do not respond to conservative treatment or for those at highest risk of fracture. Transient osteoporosis of the hip needs to be distinguished from AVN to avoid unnecessary surgical intervention.

Competing interests     

The authors declare no competing interests.

Authors' contributions     

All the authors have read and agreed to the final manuscript.

Figures     

Figure 1: coronal T2-weighted magnetic resonance image; increased signal uptake within the right femoral head and neck

Figure 2: axial T1-weighted magnetic resonance image: decreased signal uptake within the right femoral head and neck

Figure 3: saxial T2-weighted magnetic resonance image: increased signal uptake within the right femoral head and neck

References