Avascular Necrosis of Hip: Treatment Options
Treatment options for AVN of the hip are typically separated into operative and nonoperative management. Many factors will affect options for management. There is no definitive or clear pattern on speed of progression, which complicates decision making. It is important to rule out secondary causes of avascular necrosis of the femoral head (AVNFH) and ask historical questions about chronic steroid use, alcohol use, clotting disorders, sickle cell disease, autoimmune disease, or trauma.
In general, nonoperative management studies have conflicting results. It is important to identify risk factors and treat them accordingly e.g. anticoagulation if clotting disorder is present, halt alcohol use, etc. Bisphosphonates act to slow bone resorption and treatment with this class has conflicting evidence. One uncontrolled study with 294 patients showed improvement in pain and clinical function when taking alendronate 10 mg daily. The benefit was shown at three years, but not eight years . Another study with 40 patients showed less collapse [7 vs. 76 percent] while taking alendronate 70 mg weekly . One two year randomized controlled trial did not find a significant difference in outcome with oral alendronate versus placebo and a 2016 meta-analysis concluded bisphosphonate therapy did not significantly reduce the progression to collapse [3-4].
Image 1. Staging of AVN of the hip (courtesy of AAOS)
Platelet rich plasma (PRP) and mesenchymal stem cells (MSCs) have also been used for nonoperative treatment of AVNFH. PRP is a centrifuged fraction of plasma that is a thrombocyte concentrate; it is an autologous source of cellular growth factors that aids in and augments tissue repair along with the other cells of wound healing. MSCs are capable of enhancing tissue regeneration by differentiating into various mesenchymal phenotypes, such as osteoblasts, chondrocytes, and adipocytes . They are often used in conjunction and there are very limited studies on usage without surgery.
Table 1. Staging and success rate of AVN of the hip (Adopted from )
Both vascularized (VBG) and non-vascularized bone grafts (NVBG) have also been used for supplementation. NVBGs can be categorized as autograft versus allograft, cancellous, and cortical. Vascularized bone grafts are categorized as free or pedicled grafts. Free vascularized bone grafts involve removal of bone from its original (donor) blood supply, transplanting it to the affected area, and anastomosing the graft to the local blood supply. Historically, free vascularized bone graft (VBG) applications for the upper extremity have included reconstructions after tumor resection, significant infections, or trauma .
Image 2. Illustration of microsurgical vascularized bone graft for hip AVN (courtesy of pennmedicine.org)
Total hip arthroplasty (THA) remains a mainstay in treatment with advanced disease and in developed countries it is estimated to be responsible for 5 to 12% of total hip arthroplasties. It is preferred to be done in patients older than 40 years old. Younger patients have been shown to have a greater amount of aseptic loosening, a higher rate of linear wear of the polyethylene liner and a higher rate of osteolysis. More recent techniques including a cemented stem and cementless cup have yielded excellent long-term outcomes .
Image 3. Before and after a hip replacement for AVN (courtesy of researchgate.net)