Pericollapse Stage of Osteonecrosis of the Femoral Head: A Last Chance for Joint Preservation

Zhang, Qing-Yu; Li, Zi-Rong; Gao, Fu-Qiang; Sun, Wei

Limitations of this research concerning pericollapse ONFH merit consideration. First, there are some common flaws existing in now available joint-preserving studies, for example, no powered randomized controlled trials, the inclusion of ONFH with different risk factors (i.e., glucocorticoid, alcohol, trauma, caisson, and sickle cell disease), and a lack of validated patient-oriented evaluation parameters and variability with respect to indications, staging system, surgical procedures, determination of success (progression or conversion to THA), and follow-up duration. [3, 8] Second, there is a paucity of large-scale (even >10 subjects) studies with long-term follow-up (>10 years) investigating the pericollapse stage. Most studies involving joint-preserving techniques were mainly targeted at ARCO or Steinberg Stage I/II ON, and a large number of investigators have adapted the Ficat system, which was incapable of discriminating the pericollapse stage as a distinctive stage. [1, 3] Last but not least, for many studies using Steinberg or ARCO classification systems to assess ONFH, the CT results were missing. [18, 21, 22, 24, 25, 37, 39] In these studies, many alleged Steinberg or ARCO I/II ONFH cases with obvious hip pain may have been actually at the pericollapse stage. A high index of suspicion is required when younger patients present with worsening hip pain and BME, but no apparent collapse observed on X-ray.