The pB-C2 Serves as an Optimal Evaluation Parameter For The Surgical Management of Patients With Type A Basilar Invagination

ObjectiveThis study aimed to evaluate the clinical applicability of pB-C2 in assessing reduction and ventral decompression, and to examine its association with postoperative neurological outcomes in patients with type A basilar invagination (BI).MethodsA retrospective analysis was conducted on 56 surgically treated patients with type A BI and 43 controls. Neurological recovery was assessed using the Japanese Orthopedic Association (JOA) score and its improvement rate. Radiological parameters were measured, and correlation, linear regression, and receiver operating characteristic (ROC) analyses were performed.ResultsThe preoperative pB-C2 value in the BI group was significantly higher than that in controls (<i>P</i> < 0.001). Following surgery, 44 of 56 patients showed satisfactory improvement in the JOA score, while 12 demonstrated limited recovery. The mean postoperative pB-C2 decreased from 12.5 ± 2.0 mm to 8.1 ± 1.8 mm (<i>P</i> < 0.01). Significant correlations were identified between cosα·pB-C2 and the modified atlantoodontoid interval (mADI), as well as between cosβ·pB-C2 and Chamberlain's line (CL), McRae's line (ML), and Wackenheim's line (WL) (<i>P</i> < 0.05). Moreover, postoperative pB-C2 and its improvement rate were strongly associated with the cervicomedullary angle (CMA) and the JOA improvement rate. ROC analysis revealed that a postoperative pB-C2 of 8.4 mm or an improvement rate of 80.0% yielded the optimal Youden index.ConclusionThe pB-C2 provides a practical metric for assessing surgical reduction and ventral decompression in type A BI. Its correlation with the CMA and neurological recovery supports further exploration of pB-C2 as an intraoperative tool in patients with type A BI.