[Clinical efficacy of anterior cervical mortise-tenon corpectomy and fusion for the treatment of ossification of the posterior longitudinal ligament].

OBJECTIVES: For the segmental ossification of cervical posterior longitudinal ligament (OPLL) accompanied by spinal cord compression, anterior cervical corpectomy and fusion (ACCF) can achieve direct decompression through removal of most of the involved vertebral body. However, reconstruction-related complications such as titanium mesh cage subsidence, loss of cervical lordosis, and poor bone fusion are common after surgery. This study aims to investigate the clinical efficacy of a novel anterior cervical mortise-tenon corpectomy and fusion (ACMTF) technique, designed based on principles of biological reconstruction and traditional structural mechanics, for the treatment of segmental cervical OPLL, and to compare its outcomes with those of conventional ACCF.

METHODS: A retrospective analysis was conducted on patients with segmental cervical OPLL who underwent anterior surgery in the Department of Spinal Surgery, Xiangya Hospital, Central South University, between January 2020 and May 2024. Among them, 30 patients underwent ACMTF (ACMTF group). Using propensity score matching at a 1꞉1 ratio, 30 patients who underwent conventional ACCF during the same period were selected as controls (ACCF group). In the ACMTF group, an ultrasonic osteotome was used to perform V-shaped osteotomy of the anterior vertebral body. After removal of the posterior ossified lesion, the V-shaped autologous bone block was restored in situ to form a mortise-tenon structure and fixed with an intervertebral fusion cage and anterior titanium plate. The ACCF group underwent conventional subtotal corpectomy and titanium mesh reconstruction. Surgical time, intraoperative blood loss, perioperative and follow-up complications, and Japanese Orthopaedic Association (JOA) score, JOA recovery rate, Neck Disability Index (NDI), and Visual Analogue Scale (VAS) score at different follow-up time points before and after surgery were compared between the two groups. Imaging examinations were used to evaluate and compare occupation ratio (OR), space available for the spinal cord (SAC), fusion rate, implant subsidence rate, and changes in cervical lordosis angle.

RESULTS: After propensity score matching, there were no statistically significant differences between the 2 groups in baseline characteristics including sex, age, disease duration, body mass index, and surgical segments (all P>0.05), indicating good comparability. The mean operative time in the ACMTF group was 164.5 minutes, which was significantly longer than 128.4 minutes in the ACCF group (P<0.05). The mean intraoperative blood loss was 385.9 mL and 352.4 mL in the ACMTF and ACCF groups, respectively, with no statistically significant difference (P>0.05). At the final follow-up, JOA score, VAS score, and NDI in both groups were significantly improved compared with preoperative values (all P<0.05), while no statistically significant differences were found between the groups at the same time points (P>0.05). Postoperatively, OR was significantly decreased and SAC was significantly increased in both groups compared with preoperative levels (all P<0.05), with no statistically significant intergroup differences (P>0.05). At 12 months after surgery, the fusion rate was 100% in the ACMTF group and 93.3% in the ACCF group, with no statistically significant difference (P>0.05). No severe implant subsidence occurred in the ACMTF group, which was significantly lower than the 20.0% incidence in the ACCF group (P<0.05). At 6 and 12 months postoperatively, maintenance of cervical lordosis angle was significantly better in the ACMTF group than in the ACCF group (P<0.05). Regarding complications, one case of cerebrospinal fluid leakage occurred in each group (3.3%), both of which healed after lumbar cistern drainage and local compressive dressing. Six cases of severe titanium mesh subsidence occurred in the ACCF group, but none of the patients showed obvious clinical symptoms or required revision surgery. No other severe complications occurred in either group.

CONCLUSIONS: ACMTF for segmental cervical OPLL can achieve neurological decompression, neurological recovery, and pain relief comparable to those of ACCF. The in situ restoration design of the autologous bone block based on the mortise-tenon principle enables stable mechanical interlocking at the surgical site, effectively prevents severe graft subsidence, better maintains physiological cervical curvature, and achieves reliable bony fusion. Therefore, ACMTF represents a safe and effective anterior biological reconstruction strategy for the treatment of segmental cervical OPLL.