Baseline characteristics of the enrolled cases.

Objective
This study aimed to characterize a specific radiographic manifestation of lumbar rheumatoid spondylitis.
Methods and materials
The patients diagnosed with lumbar rheumatoid spondylitis who underwent posterior lumbar fusion surgery between 1/6/2019 and 30/4/2023 in the Department of Orthopedic Surgery in our hospital were retrospectively studied (RA group). The patients diagnosed with lumbar disc herniation with nucleus pulposus migration (cranial or caudal) were also collected for comparison (control group). The clinical data and radiographic manifestations were compared and analyzed.
Results
A total of 14 patients in the RA group and 36 patients in the control group were enrolled in the current study. In the RA group, seven patients had nucleus pulposus migration, among whom five patients exhibited distinct calcification (5/7, 71.4%). Of the 36 patients in the control group, 10 patients demonstrated migrated nucleus pulposus calcification (10/36, 27.8%). The migrated nucleus pulposus in the RA patients exhibited diffuse calcification, while the migrated nucleus pulposus in the control group exhibited spot-like or shell-like calcification. In addition, nucleus pulposus migration and calcification in the RA group were more likely to occur in older patients, affect the higher lumbar levels and combine with intervertebral space collapse compared with the control group.
Conclusions
Nucleus pulposus migration and calcification is specific in RA patients. It may be a characteristic radiographic sign to establish a lumbar rheumatoid spondylitis diagnosis. The potential mechanism is still unclear and need to be further explored.

研究目的
本研究旨在阐明腰椎类风湿性脊柱炎的特异性影像学特征。

材料与方法
回顾性分析我院骨科于2019年6月1日至2023年4月30日期间收治的、行后路腰椎融合术且确诊为腰椎类风湿性脊柱炎的患者，设为类风湿关节炎（Rheumatoid Arthritis, RA）组；同时纳入确诊为腰椎间盘突出症伴髓核移位（颅侧或尾侧移位）的患者作为对照组。对两组患者的临床资料与影像学表现进行对比分析。

结果
本研究共纳入RA组患者14例，对照组患者36例。RA组中7例患者出现髓核移位，其中5例可见明确钙化（5/7，71.4%）；对照组36例患者中，10例出现移位髓核钙化（10/36，27.8%）。RA组患者的移位髓核呈弥漫性钙化表现，而对照组移位髓核则呈斑点状或壳状钙化。此外，与对照组相比，RA组的髓核移位与钙化更易发生于老年患者，累及更高位腰椎节段，且常合并椎间隙塌陷。

结论
髓核移位伴钙化在RA患者中具有特异性，可作为腰椎类风湿性脊柱炎诊断的特征性影像学征象。其潜在发病机制尚未明确，有待进一步探索研究。