Spontaneous osteonecrosis of the knee: what do we know so far? A literature review.

Spontaneous osteonecrosis of the knee (SONK) is said to be a relatively common disease which may lead to an end-stage osteoarthritis of the knee. The aim of this paper was to review the literature on this field published until now, discuss the results of both conservative and surgical treatment options, as well as to introduce new methods of treatment, which may be applicable in SONK treatment.We searched the PubMed and Cochrane databases until November 2019 and presented the most recent findings in this work.The exact aetiology of SONK still remains unclear; however, recent studies suggested that early stage of SONK is rather a result of the subchondral fracture than primary osteonecrosis. So far described conservative treatment includes non-weight bearing or protected weight bearing with a knee brace, nonsteroidal anti-inflammatory drugs, analgesics, and bisphosphonates. Surgical management includes arthroscopic debridement, core decompression, osteochondral autograft, high tibial osteotomy, and unicompartmental knee arthroplasty or total knee arthroplasty.Although the aetiology of SONK remains unknown, there are many treatment options, and the choice of the most suitable one is challenging. We think that subchondroplasty may be one of the effective methods.