Stability in Pelvic Triple Osteotomies in Children Using Resorbable PLGA Screws for Fixation.

BACKGROUND: The triple pelvic osteotomy (TPO) is a major redirectional osteotomy used to improve the acetabular coverage of the femoral head in selected pediatric patients with hip disorders. Traditionally the iliac osteotomy is stabilized by metal screws that require a second surgery for removal. Despite favorable results for both adults and children in related pelvic osteotomies, resorbable implants have not previously been used for TPOs.This study aims to suggest a novel modified TPO surgical method in children using resorbable poly lactic-co-glycolic acid (PLGA) screws for fixation and to radiographically evaluate the postoperative stability achieved by these implants in a case series. METHODS: All patients (n=11) with dysplasia of the hip (2), Perthe disease (5), or Down syndrome (4), who underwent primary TPO surgery during 2013 to 2019, using resorbable PLGA screws for fixation were included. The stability of the osteotomy was evaluated in the postoperative radiograph series using the acetabular index, migration percentage, Sharp's angle and the center-edge angle. The osteotomy angle was introduced as a parameter to confirm the postoperative integrity of the achieved correction. All cases were evaluated until radiographic healing of the iliac osteotomy. Hospital notes were analyzed for complications or local reactions in relation to the implants. RESULTS: In all studied hips, the overall achieved correction was well maintained. The mean (SD) correction achieved, from the preoperative images to the last measurable postoperative image, was a 16.7 degrees decrease for Sharp angle, a 20.9 degrees decrease in acetabular index and a 24.7 degrees increase for the center-edge angle, respectively. There were no complications related to the bioabsorption of the implants. CONCLUSION: The present findings suggest that the modified TPO method, using resorbable PLGA screws, provides sufficient stability and appears to be a promising alternative to traditional TPO. Avoiding implant removal is a major benefit in a pediatric population. Resorbable screws enable the surgeon to place implants with more degrees of freedom since later implant removal is not a limiting factor. LEVEL OF EVIDENCE: Level IV-case series.

The Ambiguity of Names and Landmarks in Radiographs of the Pediatric Pelvis: Variations and a Historical Perspective.

For over a century, the plain radiograph has been used to measure and predict the development of pediatric hip conditions. Classic measurements, such as the acetabular index, the center-edge angle, and the migration percentage, have stood the test of time and remain the default tools for any pediatric orthopaedic surgeons. However, in contemporary research, the terminology regarding these measurements has become markedly inconsistent. A substantial number of synonyms, acronyms, and similar, but not identical, terms are used to label measurements. This is perhaps unsurprising, considering decades of use and numerous suggested modifications. The results of treatment cannot be reliably compared if the measured parameters are not identical, and scientific analysis of disease requires consistent terminology. In this review, we aim both to provide historical definitions and identification of radiographic landmarks commonly used in three parameters of interest on pediatric AP radiographs and to examine the variability of landmarks and definitions in contemporary research.

Postoperative stability following a triple pelvic osteotomy is affected by implant configuration: a finite element analysis.

BACKGROUND: The triple pelvic osteotomy is an established surgical method with multiple modifications regarding surgical technique and choice of implant. The stability of the osteotomy is affected by numerous factors, and among these, the three-dimensional implant configuration is a scientifically less explored aspect. METHODS: We used a finite element model of a hemi-pelvis with a standardized triple osteotomy to calculate relative flexibility for loads in all translational degrees of freedom for five different implant configurations. Two of the configurations used entry points only feasible when implant removal was not necessary. RESULTS: The stability of the osteotomy improved with an increased distance between the implants in the plane of the osteotomy as well as for a more perpendicular angle relative to the osteotomy plane. The implant configurations with more entry points available made this easier to adhere to. CONCLUSION: The use of bioabsorbable implants may provide better opportunities for optimal implant constructs which can, to a certain degree, compensate for the lesser mechanical stiffness of bioabsorbable polymers as compared to metal implants.

Hip displacement in relation to age and gross motor function in children with cerebral palsy.

PURPOSE: Hip dislocation in cerebral palsy (CP) is a serious complication. By radiographic screening and prophylactic surgery of children at risk most dislocations can be prevented. CPUP, the Swedish CP registry and follow-up program, includes annual radiographic examinations of children at Gross Motor Function Classification System (GMFCS) levels III-V. Data from CPUP were analysed to assess the risk of hip displacement in relation to GMFCS levels and age. METHODS: All children at GMFCS levels III-V (N = 353) whose first radiographic screening occurred before 3 years of age were followed between the ages 2-7 years. Migration percentages (MPs) were recorded annually (1,664 pelvic radiographs) and analysed using discrete time survival analysis. RESULTS: The risk of hip displacement between 2 years and 7 years of age was significantly (p < 0.05) higher for children at GMFCS level V during the entire study period. The risk was highest at 2-3 years of age and decreased significantly (p < 0.001) with each year of age (OR = 0.71, 95 % CI 0.60-0.83). The cumulative risk at age 7 years for those at GMFCS V for MP ≥ 40 % was 47 % (95 % CI 37-58). The corresponding risk at GMFCS IV was 24 % (16-34) and at GMFCS III 23 % (12-42). CONCLUSIONS: Children at GMFCS V have a significantly higher risk of hip displacement compared with children at GMFCS III-IV. The risk is highest at 2-3 years of age. The results support a surveillance program including radiographic hip examinations as soon as the diagnosis of severe CP is suspected.