The relationship of neural structures to arthroscopic posterior portals according to knee positioning.

PURPOSE: The purpose of this study was to investigate the relationship between the proximity of neural structures to standard posterior portals in different knee positions. METHODS: Ten fresh cadaveric knees were used to establish the standard posteromedial and posterolateral portals using an outside-in technique with arthroscopic transillumination. The distance from each portal site to the adjacent neurovascular structures (infrapatellar branches of the saphenous nerve) and the sartorial branch of saphenous nerve from the posteromedial portal, and the common peroneal nerve from posterolateral portal was measured using a precision caliper. Distances were recorded with the knees in extension, 45° of flexion and 90° of flexion in order to examine the effect of dynamic knee motion on nerve position. RESULTS: The mean distance between the posteromedial portal and the superior and inferior branches of infrapatellar branches of the saphenous nerve at full extension was significantly greater than at 90° of flexion. However, there was no difference observed between at 45° and at 90° of flexion. The mean distance from the posteromedial portal to the sartorial branch of saphenous nerve at 90° of flexion was significantly greater (26.1 mm, SD: 4.7) than that at 45° of flexion (18.4 mm, SD: 4.6), and at full extension (14 mm, SD: 4.3) (P < 0.0001). The mean distance between the posterolateral portal to the common peroneal nerve at 90° of flexion was also significantly greater (25.4 mm, SD: 9.2) than that at 45° of flexion (22.5 mm, SD: 8.1), and at full extension (20.1 mm, SD: 9.1) (P < 0.0001). CONCLUSION: In this cadaveric study, it shows that position of 90° knee flexion is reasonably safe, in order to establish a posterior portal in knee arthroscopy using the technique described in the current study, especially to avoid the sartorial branch of saphenous nerve and the common peroneal nerve injuries. Results of this study suggest the establishment of posterior portals, while the knee is flexed at an angle of 90° is recommended to ensure the safety of these structures.

The musculoskeletal manifestations of Prader-Willi syndrome.

BACKGROUND: 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. METHODS: 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. RESULTS: 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%). CONCLUSIONS: 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.