Costoplasty remains useful in the treatment of adolescent idiopathic scoliosis, rib hump and associated chest wall deformities. However traditional costoplasty increases morbidity and blood loss. We examine the feasibility and possible effectiveness of a more conservative costoplasty using an animal model.

4 fresh half Ovine rib cages from separate animals were obtained, stored at +4 °C and warmed to room temperature before testing. Each rib cage was randomly assigned to group 1, 2, 3 or 4. Ribs 2–10 were dissected out for testing. The ribs then underwent stepwise deconstruction according to their group. Beginning at the convexity, removing first the convex cortex, then the cancellous, then the cranial and caudal cortices to leave just the concave cortex. Testing for stiffness was by three-point bending on the concave side of each rib with the rib fixed at the head of the rib and 5 cm from the resected area. The ribs were deformed at a constant rate of 0.5 mm.sec ⁻1 up to a maximum load of 9.99 kg or until fracturing. Then stress was plotted against strain to find the Young's modulus of each group and statistics carried out with an ANOVA test. The ribs in each group were as follows: Group 1= control, group 2= 30 mm long convex side cortical bone removed 10 mm from lateral tubercle, group 3= convex, cortical and cancellous bone removal and group 4= removal of convex, caudal and cranial cortices with cancellous removal.

The Young's Modulus of the groups were: 1= 3.38 N-m (+/− 0.84), 2= 2.65 N-m (+/− 1.58), 3= 1.55 N-m (+/− 0.55) and 4= 0.74 N-m (+/− 0.55). Groups 3 and 4 were significantly less stiff than group 1 (p< 0.01.) No ribs in groups 1, 2 and 4 fractured under the maximum load. 5/8 ribs in group 3 fractured before the maximum load was administered.

By deconstructing the rib down to only the concave side it becomes significantly more flexible by approximately 4.5 times than the control Ribs. Coupled with its increase in flexibility it still retains its ability to withstand up to 10 kg of load without fracture. It may be possible to perform a costoplasty whilst preserving ventilatory integrity. This may improve rib hump correction, and curve correction due to increased flexibility of the stiff thoracic cage.

Boys affected by Duchenne Muscular Dystrophy (DMD) often develop significant scoliosis in the second decade of life and require scoliosis surgery. Our aim was to establish whether cardiac MRI (CMR) improves the preoperative risk assessment in DMD patients and evaluate the current risk of surgery.

Case records were retrospectively reviewed for 62 consecutive DMD boys who underwent pre-surgical evaluation at a single tertiary neuromuscular centre between 2008–2013.

62 DMD patients aged 7–18 years underwent pre-operative assessment for a total of 70 procedures (45 spinal, 19 foot, 6 gastrostomy). Echocardiography data were available for 68 procedures. Echo revealed a median left ventricular (LV) shortening fraction (SF) of 29% (range: 7–44). 34% of boys (23/68) had abnormal SF <25%, 48% (31/65) showed dyskinesia and 22% (14/64) had LV dilatation. CMR was routinely performed on 35 patients. Of those who underwent CMR, median left ventricular ejection fraction (LVEF) was 52% (range: 27–67%), 71% of boys (25/35) had dyskinesia. Echocardiography shortening fraction (SF) correlated significantly with CMR LVEF (r_s = 0.67; p<0.001). Increasing severity of dyskinesia on CMR correlated with reduced CMR LVEF (r_s = −0.64; p<0.001) and reduced echo SF (r_s = −0.47; p = 0.004). Although functional echocardiography and CMR data tended to correlate in 35 DMD boys who underwent both imaging modalities nine (26%) had discrepant results. Seven (20%) had evidence of dysfunction on CMR (LVEF < 55%) not detected on echocardiography (SF ≥ 27%); in two cases echocardiogram measured worse function than CMR.

Based on multi-disciplinary risk assessment, surgery was considered too high risk in 23 out of 67 (34%) cases. In 21 cases (91%) this was due to underlying cardiomyopathy. The highest risk among older boys assessed for spinal surgery; 21 out of 43 (49%). Of 19 boys undergoing spinal surgery, six (32%) experienced complications: two wound infections; three patients required readmission to intensive care; one patient died in the post-operative period with acute heart failure.