Low bone mineral density of the spine in adolescents with cerebral palsy relates to reduced correction of scoliosis after surgery

Abstract

Abstract Adolescents with cerebral palsy (CP) often require scoliosis surgery. Low bone mass may counteract benefits of surgical treatment. This study compares volumetric bone mineral density (vBMD) in adolescents with CP to age and sex matched healthy controls and evaluates its effect on scoliosis treatment. Computed tomogramms (CT) of 51 adolescents with CP (15.0 ± 2.6 years) were performed for scoliosis surgery and also used for vBMD calculation. Reference control vBMD values were calculated from 62 CT examinations of patients (15.1 ± 2.3 years) after trauma or conditions not related to bone mass. Z-scores were calculated based on the reference values. Correction of scoliosis in relation to vBMD was evaluated on perioperative spinal radiographs of operated adolescents with CP. Adolescents with CP had lower vBMD (123.3 ± 46.3 mg/cm 3 ) than healthy controls (166.9 ± 31.4 mg/cm 3 ). The lowest vBMD (97.3 ± 49.8 mg/cm 3 ) had patients with CP and pathological fractures ( n  = 8). Male CP Z-scores (− 2.2 ± 1.6, n  = 22) (16.2 ± 2.5 years) were significantly lower than female CP Z-scores (− 1.0 ± 1.3, n  = 29) (14.1 ± 2.3 years). Higher vBMD (179.2 ± 45.4 mg/cm 3 , n  = 41) correlated to scoliosis correction > 50% (average 67.0 ± 12%), while lower vBMD (134.9 ± 30.9 mg/cm 3 , n  = 7) related to correction ≤ 50% (average 36.8 ± 14%). Non-ambulant adolescents with CP have lower vBMD values compared to a healthy population, which negatively affects surgical correction of scoliosis. Level of evidence/clinical relevance: Therapeutic Level III.