The musculoskeletal manifestations of Prader-Willi syndrome

Prader-Willi syndrome (PWS) is a rare genetic disorder with an associated anomaly in chromosome 15, and has been reported to increase prevalence of scoliosis, but little information is available regarding its association with other musculoskeletal manifestations. The aim of this study was to evaluate musculoskeletal manifestations in 36 patients with PWS and to determine the effects of risk factors, such as, sex, age, genotype, and body mass index (BMI) on PWS.

The investigators subjected 36 patients with PWS to a complete physical examination and radiographic assessment at an orthopaedic clinic using a single protocol. Demographics, genetic analysis findings, diagnosis, fracture and surgical histories, walking age, and ambulatory status were recorded. Age, sex, height, weight, and BMI were assessed. A systemic physical examination was performed at the orthopaedic clinic. Radiographic evaluations were assessed, including those of the spine, hip joints, lower extremities, and feet.

Obesity was not found to be correlated with sex, genotype, scoliosis, kyphosis, hip dysplasia, limb malalignment, or foot abnormalities. Of the 36 patients, 23 (63.9%) had scoliosis (the scoliosis group) and 13 did not (the nonscoliosis group). Female sex was found to be significantly associated with scoliosis [11 (47.8%) of 23 in the SG vs. 1 (7.7%) of 13 in the NSG; P=0.0253]. No intergroup difference was found regarding age, genotype, BMI, or other musculoskeletal abnormalities. However, scoliosis was found to be significantly associated with limb malalignment (P=0.04589). Six patients showed kyphotic deformity associated with scoliosis. In addition, kyphoscoliosis was found to be significantly associated with the presence of a foot abnormality (P=0.01607) and severe limb malalignment (P=0.00344). Hip dysplasia was present in 8 of the 36 patients (22.2%). Limb malalignment was present in 28 patients (77.8%), and 18 (50%) had bilateral or unilateral genu varum deformity. Foot abnormalities were present in 17 patients (47.2%).

This study shows a high prevalence of spinal deformity, limb malalignment, and foot abnormality in PWS. The prevalences of musculoskeletal abnormalities were not found to be affected by age, genotype, or obesity. However, several musculoskeletal abnormalities were found to be correlated with each other, namely, scoliosis and limb malalignment, kyphotic deformity, and foot abnormality or severe limb malalignment. The authors recommend that pediatric orthopaedic surgeons conduct systemic clinical and radiographic evaluations for scoliosis, hip dysplasia, foot abnormalities, and lower limb malalignment annually, because musculoskeletal problems can be concealed by obesity.