The influence of heterotopic ossification on clinical and radiological out- comes after total lumbar disc replacement with M6-L prosthesis: a multicenter study

Abstract

Objective. To assess the degree of influence of heterotopic ossification on the motion amplitude of the operated segment and on clinical outcomes in patients after total intervertebral disc replacement. Material and Methods. Results of total replacement of the intervertebral disc with the M6-L prosthesis were analyzed in 74 patients aged 23–45 years. Follow-up period was 36 months. The motion amplitude of operated segments and the degree of heterotopic ossification were estimated. Clinical outcomes were analyzed based on pain syndrome severity according to the VAS and on the level of the back pain-related quality of life ac- cording to the Oswestry index. Results. Signs of heterotopic ossification were found in 27 (36.4%) patients: Grade I – in 11 (14.8 %), Grade II – in 14 (18.9 %), and Grade III – in 2 (2.7 %). The mean values of the motion amplitude of operated segments, VAS score and Oswestry index in the group of patients without signs of heterotopic ossification were 11.2° ± 2.7°, 2.8 ± 1.2 cm and 17.3 ± 6.5 %, respectively, and those in the group of patients with signs of heterotopic ossification – 11.5° ± 1.2°, 3.4 ± 1.8 cm and 19.8 ± 7.3 %, respectively. Conclusion. Heterotopic ossification following total lumbar disc replacement occurs in 36.4 % of cases. High grade of heterotopic ossification reli- ably affects the amplitude of segment motion, though there was no significant influence on clinical results in patients.

Keywords

• intervertebral disc
• degeneration
• fusion
• total replacement
• heterotopic ossification