Osteonecrosis of the femoral head (ONFH) is a condition where the femoral head vascularity is deficient, leading to the death of the osteocytes and bone marrow . This condition usually affects young adults and usually starts unilaterally, but bilateral affection can reach up to 75% of the cases [15, 16]. According to the etiology, it could be primary (no definitive cause) or secondary, which is caused by the use of Corticosteroids or excessive alcohol intake in about 80% of the atraumatic ONFH cases [15, 17]. Although ONFH can manifest itself in plain hip radiographs, MRI is considered the investigation of choice for detecting the early stages of ONFH . Management ranges from conservative lines in the early stages, which includes protected weight-bearing, antiresorptive treatment, and joint preservation surgery such as core decompression; however, this could be of value in the early stages of the disease. THA should be the solution if the femoral head shows advanced affection and collapses .
The evidence showed a strong correlation between Corticosteroids use and ONFH development [3, 18, 19, 10]; however, the pathophysiology of such correlation is still unclear, which could be multifactorial, including possible fat emboli formation, increased intraosseous pressure caused by fat cell hypertrophy, hyperlipidemia, and endothelial dysfunction, all of these possible factors could contribute to bone marrow ischemia and subsequent necrosis .
During COVID-19, Corticosteroids were widely used to prevent acute lung injury and progression of acute respiratory distress syndrome; furthermore, the RECOVERY group showed that administration of 6 mg dexamethasone daily for ten days reduced the 28-day mortality rate . The massive use of corticosteroids was expected to result in certain complications such as bone marrow osteonecrosis, diabetes, secondary infections, and possibly increased mortality rates .
Agarwala et al. reported on three patients who suffered from ONFH after recovering from COVID-19 infection; their patients received corticosteroids as part of the management protocol, the prescribed mean dose was equivalent to 758 mg of prednisolone, which was less than 2000 mg equivalent ceiling, which is recommended to avoid ONFH . The previous remark by Agarwala et al. study indicates that some other factors could contribute to osteonecrosis development rather than the known effect of corticosteroids use.
Patients affected with COVID-19 disease may face some coagulopathies, attributed partially to an immune-mediated vascular affection with subsequent microvascular endothelial dysfunction leading to an increase in procoagulant thrombin combined with shutting down of the fibrinolytic cascade, this results in a hypercoagulable state with possible thrombosis; this could be aggravated more by the prolonged recumbency [23, 24]. This mechanism could explain the bone marrow ischemia in COVID-19 patients with subsequent osteonecrosis.
In a report by Ardoy and Aguilera of a patient presented by knee medial condyle osteonecrosis after having COVID-19 infection , the authors reported that their patient received a small and safe dose of prednisolone; however, their patient had an antiviral medication which the authors considered as a possible risk for developing osteonecrosis as suggested in previous reports .
Although the occurrence of ONFH post-COVID-19 infection seems to be multifactorial, most authors stressed on the judicious use of Corticosteroids to guard against the development of severe complications of its prolonged and cumulative use, especially in high doses [3, 26, 4]. As all of the affected patients in the current report are considered young contradictory to the report by Sulewski et al. where the mean age of the included patients was 61, with only one of ten patients is under the age of 40 , we recommend close monitoring, and early screening of patients who were diagnosed with COVID-19, especially those who received Corticosteroids to help early diagnosis and management of ONFH, as effective joint preservation surgery depends mainly on early diagnosis.