Quantitative gait analysis in children with osteogenesis imperfecta: relationship between gait deviations and clinical features.

Osteogenesis imperfecta is a rare congenital disease of connective tissue characterized by recurrent fractures and progressive skeletal deformities which may impact on gait. The aims of this prospective study were to identify gait deviations in children with osteogenesis imperfecta compared to age-matched controls and establish relationships with clinical features. We evaluated 22 patients with different types of osteogenesis imperfecta using three-dimensional gait analysis. The incidence and location of frac- tures, fracture at birth, age at first fracture, use of intramedullary rodding and number of surgical in- terventions in the lower extremities, bone mineral density, hypermobility and number of injections of bisphosphonates were recorded for each patient. Step length was lower in the osteogenesis imperfecta group compared with the control group. Kinematics showed that sagittal pelvic and transversal hip range of motion were higher in the osteogenesis imperfecta group, whereas sagittal knee range of motion during swing phase was reduced. Regarding kinetics, hip flexion moment and hip negative power peak were significantly decreased in the osteogenesis imperfecta group. Mechanical and energetic parameters were considered as normal. The principal component analysis revealed that the bone mineral density was increased in children who had received more in- jections of bisphosphonates and these had also less deficit in kinematic parameters. Main modifications in gait parameters were observed in spatiotemporal, kinematic and kinetic data. More studies are necessary to allow stratification of severity of the osteogenesis imperfecta disease, help improve its challenging multidisciplinary treatment and ob- jectively assess treatment outcomes.

Assessment of Resection Margins in Bone Tumor Surgery.

Limb salvage surgery is now the preferred procedure for bone tumor surgery. To decrease the risk of local recurrence, it is crucial to obtain adequate resection margins. The obtained margins must be evaluated postoperatively because they influence what treatment is given subsequently when margins are not adequate (e.g., surgical revision and radiotherapy). The study aims to evaluate margin assessment of tumor specimen by MRI compared to conventional histology (to establish the viability of using MRI) and assess the accuracy of a patient-specific instrument when narrow margins were aimed. The resection margins in 12 consecutive patients that were operated on for bone tumor resection were prospectively analyzed using three methods: MRI of the resection specimen, macroscopic evaluation of specimen slices, and microscopic pathological evaluation. The assessments were qualitative (R0, R1, and R2) and quantitative (distance in mm). MRI, macroscopic, and microscopic margins generated similar results for both the qualitative (all resections were R0) and quantitative assessments. The median error in safe margins was 2 mm with a surgical guide (PSI) and 5 mm without a surgical guide. Local recurrences were not detected after a mean follow-up period of 3.7 years (range, 2.1-5 years); however, four patients died during the study. In conclusion, MRI is a valuable tool for assessing safe margins. When specimens are not available for pathological assessment (e.g., extracorporeally irradiated autograft or autoclaved autograft), MRI could be used to evaluate margins. In particular, when tumor volume is high, MRI could also help to focus the pathological examination on areas of concern.

Natural history of shelf gap and paleo-acetabular depth after shelf acetabuloplasty for Perthes disease.

The purpose of this study was to evaluate the morphologic evolution of the shelf gap, acetabulum and femoral head after shelf acetabuloplasty in patients affected by Perthes disease. 54 patients operated for Perthes disease with shelf acetabuloplasty were retrospectively reviewed regarding the radiographic results. Three pelvic antero-posterior radiographs have been studied for each patient, one at 2 postoperative months, one at 1 postoperative year and one at the latest clinical follow up (mean 76 postoperative months). The shelf gap decreased from 108% at 2 months to 104% at the last follow-up (p<0.001). There was an increase of the total acetabular depth to 168% by the presence of the shelf graft (p<0.001). The acetabular index of the operated side related to the contralateral side was 68% at 2 months due to the effect of the graft (p<0.001). The migration index of the shelf side was in mean -24% at 2 months and -3% at last follow- up (p<0.001). According to the Stulberg classification, there were 9 type 1 (17%), 20 type 2 (37%), 19 type 3 (35%), 5 type 4 (9%) and 1 type 5 (2%). A progressive remodeling with shelf gap reduction was occurring during the following months after the surgery. An increase of the total acetabular depth and a decrease of the migration index without a lateral overgrowth of the paleo-acetabulum was observed. Shelf acetabuloplasty is a good procedure to prevent early osteoarthritis by a better femoral head coverage.