Avascular necrosis of the femoral head: An exceptional complication of cushing's disease.

Avascular necrosis (AVN) of the femoral head is a well-recognized complication of steroid treatment. Exogenous glucocorticoids' administration and alcoholism are the most common nontraumatic etiologies. AVN secondary to endogenous hypercortisolism (HC) is rare; very few case reports are available on this complication. We describe a 28-year-old female that has presented an AVN with Cushing's syndrome. Biochemical investigations confirmed HC. Magnetic resonance imaging (MRI) showed a pituitary adenoma that was resected transsphenoidally. The postoperative failure directed to radiosurgery treatment. Then, the patient then expressed a significant clinical improvement while developing adrenocorticotropic deficiency; hence, steroids were indicated. During the discovery of Cushing disease, the patient presented also limping and progressive pain in right hip. The pelvis MRI showed an AVN of the right femoral head. The patient underwent a total replacement of the right hip sine presenting an extensive AVN. This case elucidates that AVN could be an early manifestation of Cushing's disease.

INTRODUCTION

Avascular necrosis (AVN) of the femoral head is a well-recognized complication of steroid treatment. Exogenous glucocorticoids’ administration and alcoholism are the most common nontraumatic etiologies.

Most corticosteroid cases are inducing osteonecrosis that is caused by exogenous doses of corticosteroid. A few case reports have described avascular osteonecrosis of the femoral head associated with endogenous hypercortisolism (HC). This article presents a case of avascular osteonecrosis caused by Cushing's disease in a young woman and discusses the clinical features of literature review.

CASE REPORT

The patient was a 28-year-old female, she signed the formal consent form in order to take part of this report. The patient was admitted in our department for Cushing's syndrome (CS). The patient had never been treated with oral, inhaled, or locally applied corticosteroids. The patient reported weight gain and secondary amenorrhea.

The patient blood pressure was 150/100 mmHg, centripetal obesity with violaceous striae, facial plethora, a buffalo hump, and supraclavicular fat pads consistent with CS.

Biochemistry investigations of blood confirmed cortisol excess, with absent diurnal cortisol rhythmicity. The free urinary cortisol excretion was high. The overnight dexamethasone suppression test failed to suppress the cortisol level. Magnetic resonance imaging (MRI) showed a pituitary adenoma of 6 mm. This adenoma has originated endocrine repercussion such as hypogonadotropic hypogonadism and metabolic disorder expressed by diabetes, hypertension, and dyslipidemia.

Pituitary adenoma was resected transsphenoidally. The postoperative evaluation objectified failure of the surgery; hence, the patient underwent a radiosurgery; the follow-up showed a remarkable clinical improvement with vanished diabetes, hypertension, dyslipidemia, and amenorrhea. Both plasma and urinary cortisol concentrations became below the detectable threshold. The patient developed adrenocorticotropic deficiency and was corrected by replacement steroids.

During the revelation of Cushing disease, the patient presented also limping and progressive pain in the right hip. The range of movement of her right hip joint was decreased. MRI of the femur showed an avascular necrosis (AVN) of the right femoral head [Figure 1].

Figure 1

Magnetic resonance imaging of pelvis showing avascular necrosis of right femoral head

The patient underwent a right total hip replacement for extensive AVN of the right femoral head with an uneventful postoperative follow-up.

DISCUSSION

CS consists of HC originated by cause and can lead to AVN. A various traumatic and nontraumatic factors can lead to AVN.[1] The most common nontraumatic AVN is originated by exogenous glucocorticoid administration and alcoholism. Although AVN of the hip is a well-recognized complication of steroid treatment, it was exceptionally reported in case of endogenous HC.[2] To date, <20 reports of AVN presenting endogenous cortisol excess feature were reported.[3] The incidence of femoral head osteonecrosis due to endogenous corticosteroid is low; moreover, patients with Cushing's disease associating sudden hip pain should be evaluated for osteonecrosis, as in the presented case.[4] The largest series of corticosteroid-induced AVN reported that 3 of 77 patients (4%) were found to suffer from endogenous CS. In the same series, exogenous glucocorticoid administration represented 31% of nontraumatic AVN, whereas alcohol intake fraction was 33% of cases. Cerletty et al. have reported that patients with idiopathic osteonecrosis of the femoral head showed endogenous hypercortisolism although its existence has not been recognized.[56] This suggests that the incidence of femoral head osteonecrosis caused by endogenous corticosteroid might be higher than reported.

Avascular necrosis is in situ death of a bone segment resulting from the interruption of blood supply.[7] The femoral head seems to be more susceptible to AVN, probably because it has very limited blood supply through the delicate artery of the ligamentum teres, which is a terminal vessel arising from the obturator artery.[2] Pain is the most common symptom of affected joint. Several hypotheses have been proposed to explain the pathogenesis of this disease process. However, the mechanism of AVN induced by glucocorticoid is not fully understood. It has been reported that glucocorticoids induce osteocyte apoptosis that constitutes the first histopathological feature of AVN, which leads to impairment of bone remodeling.[8] A theory suggests that fat embolization from the liver, bone marrow fat cells, or destabilization and coalescence of plasma lipoproteins might be responsible of the pathogenesis.[2] Another possible cause is arteriosclerosis secondary to steroid that induced hypertension and insulin resistance,[1] this might yield AVN.[9] Phillips et al. reported that the inclusion of adrenergic substances in exogenous corticosteroid treatment would enhance the effect of corticosteroid, hence originating femoral head osteonecrosis caused by exogenous HC.[10]

In the past, the diagnosis of AVN was done by conventional radiography. Thus, radiographic abnormalities are occurring in advanced stages of the disease.[2] Recent evidences showed that MRI is the gold standard for early diagnosis for recommending the appropriate treatment.[1] AVN carries a poor prognosis if untreated in the right time. The most AVN is originated to endogenous hypercortisolemia that is treated surgically.[3] Surgical treatment options are dependent on the stage of the disease, and they include core decompression, bone grafting, various osteotomies, and total hip replacement. In precollapse stages, core decompression is an effective form of treatment. In late stages 3 and 4, hip replacement surgery might be necessary.[7] Early surgical intervention allows preventing long-term complications. Although hip-preserving surgical procedures remain the mainstay of treatment in cases of atraumatic AVN, a number of medical therapies targeting pathophysiological pathways have been evaluated with varying clinical outcomes; this includes bisphosphonates, nonsteroidal anti-inflammatories, and low-molecular-weight heparin.[3] However, it is reported that 31% of patients with precollapse AVN had a satisfactory clinical outcome without surgery.[11]

CONCLUSION

This case illustrates that AVN can be the presenting manifestation or complication of Cushing's disease. AVN should be suspected in any patient with CS presenting with sudden hip pain. An MRI has to be achieved since simple radiographs are falsely negative in early stages. Surgical treatment options are dependent on the stage of the disease.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

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Conflicts of interest

There are no conflicts of interest.