Introduction. The main challenge in management of adolescent idiopathic scoliosis (AIS) is to predict which curve will progress so that appropriate treatment can be given. We previously reported that low bone mineral density (BMD) was one of the adverse prognostic factors for AIS. With advancement in imaging technology, quantitative ultrasound (QUS) becomes a useful method to assess bone density and bone quality. The objective of this study was to assess the role of QUS as a radiation-free method to predict curve progression in AIS. Methods. 294 girls with AIS were recruited at ages 11–16 years and followed up until skeletal maturity. 269 age-matched healthy girls were recruited as controls. They provided the normal reference for calculation of Z score for QUS parameters. QUS measurements, including BUA (broadband ultrasound attenuation), VOS (velocity of sound) and SI (stiffness index) of the calcaneum, BMD of femoral neck, menarche history, ages, and Cobb angle of the major curve were recorded at baseline as independent variables. The predictive outcome was curve progression defined as an increase of Cobb angle of 6° or more. Logistic regression model and the ROC curve were used for statistical analysis. Results. Mean follow-up was 3·4 years (SD 1·57). At baseline, mean age was 13·4 years (1·23), 73 (24·8%) patients were premenarchal, and mean Cobb angle was 26·3° (SD 8·2°). 202 (68·7%), 194 (66%), and 202 (68·7%) of patients with AIS had Z score of BUA, VOS, and SI of 0 or less, respectively. Initial univariate analysis indicated all independent variables had p values less than 0.2. Logistic regression analysis indicated that the p values of their regression coefficients were: age (p<0·001), menarchal status (p<0·001), Cobb angle (p=0·008), BMD (p=0·084), BUA (p=0·722), VOS (p=0·112), and SI (p=0·027). SI, age, menarchal status, and Cobb angle were therefore included in the final prediction equation. The adjusted odds ratio for Z score of SI of 0 or less was 2·00 (95% CI 1·08–3·71). The area under the ROC curve was 0·831(95% CI 0·785–0·877). The predictive model had a sensitivity of 0·847 and a specificity of 0·665 at a probability cutoff of 0·368. Conclusions. We recorded evidence of deranged bone density and bone quality in AIS, as indicated by QUS investigation. SI is an independent and significant prognostic factor for AIS. It can be used as a radiation-free parameter to predict curve progression in combination with initial Cobb angle, age, and menarchal status, especially when DXA is not available. Acknowledgments. This study is supported by Research Grant Council—The government of HKSAR (project number CUHK4498/06M)

The aim of this study was to evaluate the feasibility of using the intact S1 nerve root as a donor nerve to repair an avulsion of the contralateral lumbosacral plexus. Two cohorts of patients were recruited. In cohort 1, the L4–S4 nerve roots of 15 patients with a unilateral fracture of the sacrum and sacral nerve injury were stimulated during surgery to establish the precise functional distribution of the S1 nerve root and its proportional contribution to individual muscles. In cohort 2, the contralateral uninjured S1 nerve root of six patients with a unilateral lumbosacral plexus avulsion was transected extradurally and used with a 25 cm segment of the common peroneal nerve from the injured leg to reconstruct the avulsed plexus.

The results from cohort 1 showed that the innervation of S1 in each muscle can be compensated for by L4, L5, S2 and S3. Numbness in the toes and a reduction in strength were found after surgery in cohort 2, but these symptoms gradually disappeared and strength recovered. The results of electrophysiological studies of the donor limb were generally normal.

Severing the S1 nerve root does not appear to damage the healthy limb as far as clinical assessment and electrophysiological testing can determine. Consequently, the S1 nerve can be considered to be a suitable donor nerve for reconstruction of an avulsed contralateral lumbosacral plexus.

Cite this article: Bone Joint J 2015; 97-B:358–65.