MRI quantitative muscle characterization in children with X-linked hypophosphatemia.

INTRODUCTION: Children with X Linked Hypophosphatemia (XLH) suffer from carential ricket, bone deformities and lameness. No previous study demonstrated a morphological distinction in muscles in these patients. The aim of this prospective study was to characterize, using Magnetic Resonance Imaging (MRI), the muscle morphology of pelvis, thigh and leg in children with XLH and to compare it with typically developed (TD) children. HYPOTHESIS: We hypothesized that lower limbs muscles in children with XLH are different from TD children and could explain limp walking. MATERIAL AND METHODS: Three-dimensional reconstructions of the muscles were performed in 11 patients with XLH and 15 TD children. Muscle lengths, sections and volumes were calculated and normalized with height and weight. Mean age was 10. RESULTS: Lengths were all smaller in children with XLH except for the Medius/minimus gluteus muscles (p=0.64). The difference seemed higher in muscles with a long tendinous part as semitendinosus (0.139 vs 0,164; p<0.01). All volumes were significantly inferior in children with XLH. This preliminary study showed significant differences in muscle structures between patients with XLH and TD children. DISCUSSION: Medius/minimus gluteus seemed to be particularly developed in children with XLH. Nevertheless it is not possible to conclude if it is related to XLH or a consequence of bone deformities. LEVEL OF PROOF: IV.

Combined gait analysis and radiologic examination in children with X-linked hypophosphatemia.

BACKGROUND: X-linked hypophosphataemia causes bone deformities and gait abnormalities that tend to worsen with age in the absence of appropriate treatment. However, doctors do not currently use quantitative tools to characterize these symptoms and their possible interactions. METHODS: Radiographs and 3D gait data from 43 non-surgical growing children with X-linked hypophosphataemia were acquired prospectively. Data from age-matched typically developing children were used to form the reference group. Subgroups based on radiological parameters were compared with each other and with the reference population. Linear correlations between radiographic parameters and gait variables were examined. FINDING: X-linked hypophosphatemic patients differed from the control group in pelvic tilt, ankle plantarflexion, knee flexion moment and power. High correlations with tibiofemoral angle were found for trunk lean, knee and hip adduction, and knee abduction moment. The Gait Deviation Index was below 80 for 88% of the patients with a high tibiofemoral angle (varus). Compared to other subgroups, varus patients had augmented trunk lean (+3°) and knee adduction (+10°) and decreased hip adduction (-5°) and ankle plantarflexion (-6°). Femoral torsion was associated with alterations in rotation at the knee, and hip. INTERPRETATION: Gait abnormalities induced in X-linked hypophosphataemia have been described in a large cohort of children. Links between gait alterations and lower limb deformities were found, with varus deformities standing out. Since bony deformities appear when X-linked hypophosphatemic children start walking and have been found to alter gait patterns, we suggest that combining radiology with gait analysis may improve the clinical management of X-linked hypophosphataemia.

Quantitative analysis of lower limb and pelvic deformities in children with X-linked hypophosphatemic rickets.

INTRODUCTION: X-linked hypophosphatemia (XLH) rickets mainly causes leg deformities in children that can worsen as they grow. We hypothesized that quantifying the bone parameters will help to document and monitor these deformities in children with XLH. METHODS: Thirty-five growing children affected by XLH were included in this cross-sectional study. Biplanar radiographs were taken with an EOS system allowing three-dimensional (3D) reconstructions of the pelvis and legs. Sixteen geometric parameters were calculated for the legs and pelvis. A control group of 40 age-matched patients was used to define the reference values for these geometric parameters. RESULTS: For the legs, significant differences (p<0.05) appeared between the XLH patients and the control group in the neck-shaft angle, femur/tibia length ratio and HKS. Among the 70 legs in the XLH group, 23 were in genu varum, 25 were in genu valgum and 22 were straight. There were significant differences between the genu varum and genu valgum subgroups in the femoral mechanical angle and the HKS. A strong correlation was found between the femoral mechanical angle and femorotibial angle (r2=0.73) and between the femoral mechanical angle and HKS (r2=0.69) The sacral slope and acetabular anteversion were significant different from the reference values. DISCUSSION: Quantitative radiological parameters derived from 3D reconstructions show that the deformities in XLH patients are (1) mainly in - but not limited to - the femoral shaft; (2) highly variable from one person to another. Some of these radiological parameters may be useful for the diagnosis and monitoring of XLH patients. LEVEL OF EVIDENCE: III; case control study.

Long-term outcomes of non-invasive expandable endoprostheses for primary malignant tumors around the knee in skeletally-immature patients.

INTRODUCTION: Expandable endoprostheses are used to restore limb function and compensate for the sacrifice physis involved in carcinologic resection. Long-term outcomes of the last generation of knee "non-invasive" expandable endoprostheses are required. Objectives were to report on oncologic results of bone sarcoma resection around the knee with expandable endoprosthesis reconstruction and to compare the surgical outcomes of the "non-invasive" expandable endoprostheses used in our department. MATERIALS AND METHODS: Retrospective study that included all children with bone sarcoma around the knee that underwent tumor resection reconstructed with non-invasive expandable prosthesis. Phenix-Repiphysis was used from 1994 to 2008 followed by Stanmore JTS non-invasive from 2008 to 2016. Survival and complications were recorded. Functional outcomes included Musculoskeletal Tumor Society (MSTS) score, knee range of motion, lower limb discrepancy (LLD). RESULTS: Forty children (Sex Ratio = 1) aged a mean 8.8 years (range, 5.6-13.8) at surgery were included in the study. There were 36 osteosarcoma and 4 Ewing sarcoma that involved 33 distal femur and 7 proximal tibia. Cohort (n = 40) consisted of 28 Phenix-Repiphysis and 12 Stanmore with a mean follow-up of 9.8 ± 5.8 years and 6.1 ± 3.1 years, respectively. Postoperative infection rate was 7.5% in the cohort (3 Repiphysis). Functional results were significantly better in the Stanmore group with a mean MSTS of 87.6 ± 5.4% and knee flexion of 112 ± 38°. At last follow-up, implant survival was 100% in Stanmore group, whereas all living Phenix-Repiphysis were explanted. Mechanical failure was the primary cause for revision of Phenix-Repiphysis. Limb length equality was noted in 79% patients with Phenix-Repiphysis and 84% with Stanmore at last follow-up. CONCLUSION: Chemotherapy and limb-salvage surgery yield good oncologic outcomes. Expandable endoprostheses are effective in maintaining satisfactory function and lower limb equality. With improvements made in the last generation of "non-invasive" prostheses, implants' survival has been substantially lengthened.

Isolated Acromial Fracture in a Cyclist: A Case Report and Review of the Literature.

CASE: An isolated acromial fracture was diagnosed in a 45-year-old subject, recreational athlete, during a cycling fall on the shoulder. Clinical examination combined with x-ray and computerized tomography scan confirmed the isolated injury. Open reduction and osteosynthesis using a tension band technique was performed. The patient was immobilized in a sling for 6 weeks, and fixation hardware was removed after 6 months. At the 1-year follow-up, patient had returned to his preinjury level of athletic activity. CONCLUSION: Isolated acromial fracture is an uncommon sports-related injury. Although several treatment modalities exist, nonoperative, immobilization treatment is typically effective if fracture is not displaced. Osteosynthesis should be considered if there is subacromial impingement or fracture displacement >10 mm.

Percutaneous alcohol-based sclerotherapy in aneurysmal bone cyst in children and adolescents.

INTRODUCTION: Aneurysmal bone cyst (ABC) is a benign bone lesion of childhood and adolescence. It can be locally aggressive, with risk of fracture. Management is controversial. The aim of the present study was to assess the efficacy, simplicity and tolerance of percutaneous alcohol-bases sclerotherapy in ABC. HYPOTHESIS: Alcohol-based sclerotherapy for ABC under radiographic control is safe and effective. MATERIAL AND METHODS: A single-center retrospective study for the period 2008-2016 included all of the 55 ABCs, in 54 patients, confirmed on pathology and treated by alcohol-based sclerotherapy under radiographic control. Mean age at diagnosis was 9.6 years. ABC involved the humerus in 30 cases (54%), tibia in 7 (13%) and femur in 5 (9%). Mean follow-up was 50.9 months (range, 16-117 months). Mean number of applications was 1.7 (range, 1-4). Results were assessed clinically (pain, return to sport, limb length and alignment, revision surgery) and radiologically. The main endpoint was lesion volume reduction. The secondary endpoint was failure, defined by open revision surgery or pain preventing return to a sports activity. RESULTS: Clinical progression was favorable in 36 patients (67%), and radiological progression in 45 (85%). Only 1 cyst required secondary resection. One patient experienced spontaneously resolving intraoperative bradycardia. Male gender and young age emerged as factors for poorer response. DISCUSSION: ABC management in children can be made difficult by lesion size, aggressiveness, location, proximity to the growth plate and small bone stock. Alcohol-based sclerotherapy is simple, reliable and effective in childhood ABC, and may be a first-line attitude, avoiding recourse to invasive surgery. LEVEL OF EVIDENCE: IV, retrospective study.