Objective: To propose a new definition of the pericollapse stage of osteonecrosis of the femoral head (ONFH) and review its significance in disease diagnosis and treatment selection.
Data sources: A search for eligible studies was conducted in three electronic databases including PubMed, Cochrane Library, and Embase up to August 10, 2018, using the following keywords: "osteonecrosis", "prognosis", and "treatment".
Study selection: Investigations appraising the clinical signs, symptoms, and imaging manifestations in different stages of ONFH were included. Articles evaluating the prognosis of various joint-preserving procedures were also reviewed.
Results: The pericollapse stage refers to a continuous period in the development of ONFH from the occurrence of subchondral fracture to early collapse (<2 mm), possessing specific imaging features that mainly consist of bone marrow edema and joint effusion on magnetic resonance imaging (MRI), crescent signs on X-ray films, and clinical manifestations such as the sudden worsening of hip pain. Accumulating evidence has indicated that these findings may be secondary to the changes after subchondral fractures. Of note, computed tomography provides more information for identifying possible subchondral fractures than does MRI and serves as the most sensitive tool for grading the pericollapse lesion stage. The pericollapse stage may indicate a high possibility of progressive disease but also demonstrates satisfactory long- and medium-term outcomes for joint-preserving techniques. In fact, if the articular surface subsides more than 2 mm, total hip arthroplasty is preferable.
Conclusions: The pericollapse stage with distinct clinical and imaging characteristics provides a last good opportunity for the use of joint-preserving techniques. It is necessary to separate the pericollapse stage as an independent state in evaluating the natural progression of ONFH and selecting an appropriate treatment regimen.
股骨头坏死的围塌陷期：保髋治疗的最后良机 摘要 目的：本文提出了股骨头坏死围塌陷期的最新定义并回顾了其在疾病诊断和治疗方案选择中的意义。 数据来源：通过使用”骨坏死“、”预后“和”治疗“三个关键词，我们对包括PubMed，Cochrane图书馆和Embase（截止到2018年8月10日）在内的三个数据库进行了系统的检索，寻找合适的文献。 研究选择：纳入评价股骨头坏死不同时期的临床症状、体征和影像学表现的研究。评估不同保髋治疗预后的文章也纳入了本系统回顾。 结果：围塌陷期指的是从软骨下骨骨折到轻微塌陷（小于2mm）出现这之间的一段连续时期。这一时期的特征性表现包括核磁共振（MRI）上的骨髓水肿和关节积液，X线上的新月征和临床表现上突发的疼痛加重。越来越多的证据表明这些表现继发于软骨下骨骨折后的改变。值得注意的是，CT能够在鉴定软骨下骨骨折方面提供比MRI更多的信息，因此被认为是对围塌陷期分期最敏感的工具。围塌陷的出现表明股骨头坏死进一步进展的可能性大，同时在该期实施保髋手术有着较好的中远期效果。实际上，一旦塌陷高度超过2mm，全髋关节置换可能是更好的选择。 结论：具有明确的临床和影像特征的围塌陷期为股骨头坏死的保髋治疗提供了最后的良机。把围塌陷期作为股骨头坏死自然进展中的一个独立时期进行评估并指导治疗方案的选择是必须的。.
Keywords: Joint-Preserving Procedure; Osteonecrosis of the Femoral Head; Pericollapse; Prognosis.