Clinical and radiographic outcomes of modified anterior fusion with controlled delordosis and interspinous distraction for pincer-type cervical spondylotic myelopathy: a retrospective cohort study

Pincer-type cervical spondylotic myelopathy (CSM) is characterized by combined anterior compression and posterior ligamentum flavum buckling at the same index level. This study described clinical and radiographic outcomes after a modified anterior fusion strategy incorporating controlled delordosis and interspinous distraction, and explored whether segmental alignment and distraction changes were associated with postoperative posterior occupation. We retrospectively reviewed 62 patients with operationally defined pincer-type CSM treated at a single center from January 2019 to January 2024. Clinical outcomes were assessed using Japanese Orthopaedic Association score, Visual Analog Scale for neck pain, and Neck Disability Index. Index-level radiographic parameters included segmental Cobb angle, interspinous process distance, intervertebral height, and posterior occupation ratio (POR). Regional alignment was evaluated using the C2-7 Cobb angle and C2-7 sagittal vertical axis (cSVA). Pearson correlation and multivariable linear regression analyses were used to explore factors associated with postoperative POR. Thirty-seven patients had preoperative retrolisthesis and 25 did not. Clinical scores improved significantly after surgery (all P < 0.001). Mean intervertebral height increased by 4.5 mm, interspinous process distance increased by 3.9 mm, segmental Cobb angle decreased by 4.5°, and mean POR decreased from 24.3% to 10.7%. POR reduction showed weak correlations with Cobb angle reduction ( r = 0.283, P = 0.026) and interspinous process distance increase ( r = 0.271, P = 0.033). In multivariable analysis, baseline POR remained independently associated with postoperative POR, whereas technique-related radiographic changes were not independently significant. The mean C2-7 Cobb angle decreased by 3.6° without conversion to kyphosis, while cSVA increased by 8.0 mm. In selected patients with pincer-type CSM, modified anterior fusion with controlled delordosis and interspinous distraction was associated with clinical improvement and reduced posterior occupation at the index level. These findings are compatible with a possible posterior column tensioning effect but do not prove an independent causal mechanism or superiority over conventional approaches. No postoperative C2-7 kyphosis was observed, although the clinical relevance of the 8.0-mm increase in cSVA remains uncertain. Not applicable.