New Classification Algorithm Guiding Surgical Decision-making for Posterior Longitudinal Ligament Ossification of the Thoracic Spine: A Study of 108 Patients With Mid-term to Long-term Follow-up.

STUDY DESIGN

This is a single-center, retrospective, cohort study.

OBJECTIVE

The objective of this study was to propose a surgical classification algorithm guiding the choice of surgical approaches for ossification of the posterior longitudinal ligament (OPLL) in the thoracic spine based on the characteristics of each patient's specific pathology.

SUMMARY OF BACKGROUND DATA

Surgical decision-making in this OPLL patient population requires balancing a more definitive decompression of the thoracic spinal cord through direct decompression against a higher risk of significant complications.

MATERIALS AND METHODS

Patients with a primary diagnosis of thoracic OPLL who received surgical decompression in a tertiary spine center between May 2009 and June 2015 were included. Surgical planning was guided by our classification algorithm according to the location and the extent of OPLL in each patient. Patient demographics, neurological function using the 11-point Japanese Orthopaedic Association scale, length of procedure, estimated blood loss, the occurrence of major complications, etc., were extracted from the database of electronic medical record system. The Kruskal-Wallis test and Fisher exact test were used when data were not normally distributed.

RESULTS

A total of 115 patients (33 men and 82 women) were included in this study, among whom 108 had a follow-up of at least 12 months (average: 51.7±22.2 mo, range: 12-100 mo). On the basis of our classification algorithm, 11 patients were type I, 26 were type II, 60 were type III, 11 were type IV, and the choice of surgical decompression techniques used in each patient followed that recommended by the algorithm in all cases. On average, the Japanese Orthopaedic Association score improved from 5.0±1.8 preoperatively to 8.7±1.7 postoperatively, with a Hirabayashi improvement rate of 63.6%.

CONCLUSION

A new surgical classification algorithm guiding the choice of approach for decompression of OPLL in the thoracic spine was validated in a series of 108 patients through an analysis of their clinical outcomes and surgical complications.

LEVEL OF EVIDENCE

Level III.