AB0913 THE ROLE OF BISPHOSPHONATES IN THE MANAGEMENT OF SPONTANEOUS OSTEONECROSIS OF THE KNEE (SONK)
Authors: Mark Ford, Roshan Amarasena
Journal: Annals of the Rheumatic Diseases (2019)

<h3>Background</h3> Spontaneous osteonecrosis of the knee (SONK) was first described by Ahlbäck, Bauer and Bohnein in 1968 when they identified 39 patients with radiolucent lesions of subchondral bone in the medial femoral condyle which represented a manifestation of osteonecrosis. The aetiology and pathogenesis of SONK remains unclear with possibilities including microvascular compromise, reduced bone mineral density, and mechanical disruption within the knee. The treatment compromises of conservative, medical and surgical options depending on the severity of osteonecrosis identified on imaging. Lai <i>et al</i> (2005) demonstrated the beneficial effect of alendronate in the prevention of early collapse of the femoral head in patients with nontraumatic osteonecrosis. However, the role of bisphosphonates in the treatment of SONK is debated and the evidence is based upon a few studies. <h3>Objectives</h3> To assess the evidence for the use of bisphosphonates in SONK. <h3>Methods</h3> A literature search was conducted to identify studies reporting the effect of bisphosphonates in the treatment of SONK and the usefulness and validity of their conclusions was subsequently assessed. <h3>Results</h3> We have identified one randomised controlled trial and four case series investigating the use of a bisphosphate on the clinical and radiological outcome in patients with osteonecrosis of the knee. All four case series showed improvements with bisphosphonates on patient visual analogue scale (VAS) and radiological outcome. However, the sole randomised controlled trial reported that bisphosphonates had no additional benefit over conservative measures and anti-inflammatory medications after 24 or 48 weeks both functionally and radiographically. These studies had a small number of participants and the size of the osteonecrotic lesion was either small, which traditionally is managed conservatively, or not interpreted in the context of the results. <h3>Conclusion</h3> The role of bisphosphonates in the treatment of SONK remains unclear. Further randomised controlled trials would be beneficial in these patients with emphasis on the symptom duration and the size of the osteonecrotic lesion. <h3>References</h3> [1] Agarwala, S., Sharoff, L. and Jagani, N., 2018. Effect of zoledronic-acid and alendronate on bone oedema and pain in spontaneous osteonecrosis of the knee: a new paradigm in medical management. Revista Brasileira de Ortopedia (English Edition). Accessed via: https://www.sciencedirect.com/science/article/pii/S2255497118300089 on 31st December 2018. [2] Breer, S., Oheim, R., Krause, M., Marshall, R.P., Amling, M. and Barvencik, F., 2013. Spontaneous osteonecrosis of the knee (SONK). Knee Surgery, Sports Traumatology, Arthroscopy, 21(2), pp.340-345. [3] Jureus, J., Lindstrand, A., Geijer, M., Roberts, D. and Tägil, M., 2012. Treatment of spontaneous osteonecrosis of the knee (SPONK) by a bisphosphonate: A prospective case series with 17 patients. Acta orthopaedica, 83(5), pp.511-514. [4] Kraenzlin, M.E., Graf, C., Meier, C., Kraenzlin, C. and Friedrich, N.F., 2010. Possible beneficial effect of bisphosphonates in osteonecrosis of the knee. Knee surgery, sports traumatology, arthroscopy, 18(12), pp.1638-1644. [5] Lai, K.A., Shen, W.J., Yang, C.Y., Shao, C.J., Hsu, J.T. and Lin, R.M., 2005. The use of alendronate to prevent early collapse of the femoral head in patients with nontraumatic osteonecrosis: a randomized clinical study. JBJS, 87(10), pp.2155-2159. [6] Meier, C., Kraenzlin, C., Friederich, N.F., Wischer, T., Grize, L., Meier, C.R. and Kraenzlin, M.E., 2014. Effect of ibandronate on spontaneous osteonecrosis of the knee: a randomized, double-blind, placebo-controlled trial. Osteoporosis international, 25(1), pp.359-366. <h3>Disclosure of Interests</h3> None declared