Congenital pseudarthrosis of the tibia is an uncommon manifestation of neurofibromatosis type 1 (NF1), but one that remains difficult to treat due to anabolic deficiency and catabolic excess. Bone grafting and more recently recombinant human bone morphogenetic proteins (rhBMPs) have been identified as pro-anabolic stimuli with the potential to improve the outcome after surgery. As an additional pharmaceutical intervention, we describe the combined use of rhBMP-2 and the bisphosphonate zoledronic acid in a mouse model of NF1-deficient fracture repair. Fractures were generated in the distal tibiae of neurofibromatosis type 1-deficient (Nf1. +/−. ) mice and control mice. Fractures were open and featured periosteal stripping. All mice received 10 μg rhBMP-2 delivered in a carboxymethylcellulose carrier around the fracture as an anabolic stimulus. Bisphosphonate-treated mice also received five doses of 0.02 mg/kg zoledronic acid given by intraperitoneal injection. When only rhBMP but no zoledronic acid was used to promote repair, 75% of fractures in Nf1. +/−. mice remained ununited at three weeks compared with 7% of controls (p < 0.001). Systemic post-operative administration of zoledronic acid halved the rate of ununited fractures to 37.5% (p < 0.07). These data support the concept that preventing bone loss in combination with anabolic stimulation may improve the outcome following surgical treatment for children with congenital pseudarthoris of the tibia and NF1

Aims. The Fassier Duval (FD) rod is a third-generation telescopic implant for children with osteogenesis imperfecta (OI). Threaded fixation enables proximal insertion without opening the knee or ankle joint. We have reviewed our combined two-centre experience with this implant. Methods. In total, 34 children with a mean age of five years (1 to 14) with severe OI have undergone rodding of 72 lower limb long bones (27 tibial, 45 femoral) for recurrent fractures with progressive deformity despite optimized bone health and bisphosphonate therapy. Data were collected prospectively, with 1.5 to 11 years follow-up. Results. A total of 24 patients (33%) required exchange of implants (14 femora and ten tibiae) including 11 rods bending with refracture. Four (5%) required reoperation with implant retention. Loss of proximal fixation in the femur and distal fixation in the tibia were common. Four patients developed coxa vara requiring surgical correction. In total, 13 patients experienced further fractures without rod bending; eight required implant revision. There was one deep infection. The five-year survival rate, with rod revision as the endpoint, was 63% (95% confidence interval (CI) 44% to 77%) for femoral rods, with a mean age at implantation of 4.8 years (1.3 to 14.8), and 64% (95% CI 36% to 82%) for tibial rods, with a mean age at implantation of 5.2 years (2.0 to 13.8). Conclusion. FD rods are easier to implant but do not improve on the revision rates reported for second generation T-piece rods. Proximal femoral fixation is problematic in younger children with a partially ossified greater trochanter. Distal tibial fixation typically fails after two years. Future generation implants should address proximal femoral and distal tibial fixation to avoid the majority of complications in this series. Cite this article: Bone Joint J 2020;102-B(8):1048–1055

PURPOSE OF THE STUDY. To assess if prolonged use of Bisphosphonates in Osteogenesis Imperfecta alters the pattern of femoral fractures. Osteogenesis Imperfecta (OI) has been treated with Bisphosphonates for many years with some clear clinical benefits. In adult cohorts there are reports of a new pattern of atraumatic subtrochanteric fractures seen with Bisphosphonate treatment. SUMMARY OF METHODS. This study assesses the location of femoral fractures in a cohort of 176 OI patients treated with Bisphosphonates over a two year period and compares it to a historical control group of 45 managed prior to the advent of this specific treatment. SUMMARY OF RESULTS. review of the radiological digital archive identified 16 femoral fractures in this time period in the Bisphosphonate treated group. All but 2 were within 5cm of the lesser trochanter, and 50% within 3cm. In comparison, the historical group, composed of 26 femoral fractures had a more widespread fracture pattern with the most frequent location being the mid-diaphysis. Many of the sub-trochanteric fractures in the treatment group occurred with minimal trauma, and in some cases without any injury. CONCLUSION. It appears that concerns in the adult osteoporotic population treated with Bisphosphonates are mirrored in Osteogenesis Imperfecta. It is possible that the high bending moments in the proximal femur together with altered mechanical properties of cortical bone secondary to the use of this group of drugs, mediated by abnormal osteoclast and osteoblast function, increase the risk of this type of injury and warrants further investigation

The aim of the study was to review the effectiveness of rigid IM nailing in stabilisation and deformity correction of lower limb long bones in adolescents with metabolic bone disease which to our knowledge has not been studied before. Medical records and radiographs were retrospectively reviewed looking at indications, deformity correction, number of osteotomies-if needed, bone healing, time to healing and incidence of complications. Between Aug 2010 and Mar 2015 fifteen patients (24 segments) had rigid IM nailing. Ten patients had Osteogenesis Imperfecta, four with McCune Albright syndrome and one with hypophosphatemic rickets. 22 femora and two tibiae were IM nailed. The mean age of the patients was 13.1 (9.6–16.75 years). Eleven out 24 segments were previously rodded. Eight segments were for acute fractures. 13 bones had significant deformities requiring corrective osteotomies. One patient had previous fracture non union. All patients were allowed to partial weight bear immediately postoperatively and were fully mobile six weeks following surgery. Mean follow up was 24 months (3–51 months) post-operatively. All deformities were corrected. All fractures and osteotomies radiologically united. Mean radiological union time was 5.5 months (6 weeks – 11 months). Patients with acute fractures had mean radiological union time of 4 months. Patients who had osteotomies had a mean radiological union time of 7.1 months. The patient with previous non union had BMP at the same time and radiologically healed in 10 months. Two patients had persistent bisphosphonate osteotomy lines but were asymptomatic. One patient had removal of a prominent distal locking screw and one had persistent Trendelenburg gait. Rigid intramedullary nailing is effective in stabilisation and deformity correction of long bones in adolescent patients with brittle bone disease. The technique has a low complication rate. We recommend the use of this technique in paediatric limb reconstruction in managing metabolic bone conditions

Congenital pseudarthrosis of the tibia (CPT) is a rare but well recognised condition. Obtaining union of the pseudarthrosis in these children is often difficult and may require several surgical procedures. The treatment has changed significantly since the review by Hardinge in 1972, but controversies continue as to the best form of surgical treatment. This paper reviews these controversies.

Cite this article: Bone Joint J 2013;95-B:1027–34.

Two types of fracture, early and late, have been reported following limb lengthening in patients with achondroplasia (ACH) and hypochondroplasia (HCH).

We reviewed 25 patients with these conditions who underwent 72 segmental limb lengthening procedures involving the femur and/or tibia, between 2003 and 2011. Gender, age at surgery, lengthened segment, body mass index, the shape of the callus, the amount and percentage of lengthening and the healing index were evaluated to determine predictive factors for the occurrence of early (within three weeks after removal of the fixation pins) and late fracture (> three weeks after removal of the pins). The Mann‑Whitney U test and Pearson’s chi-squared test for univariate analysis and stepwise regression model for multivariate analysis were used to identify the predictive factor for each fracture. Only one patient (two tibiae) was excluded from the analysis due to excessively slow formation of the regenerate, which required supplementary measures. A total of 24 patients with 70 limbs were included in the study.

There were 11 early fractures in eight patients. The shape of the callus (lateral or central callus) was the only statistical variable related to the occurrence of early fracture in univariate and multivariate analyses. Late fracture was observed in six limbs and the mean time between removal of the fixation pins and fracture was 18.3 weeks (3.3 to 38.4). Lengthening of the tibia, larger healing index, and lateral or central callus were related to the occurrence of a late fracture in univariate analysis. A multivariate analysis demonstrated that the shape of the callus was the strongest predictor for late fracture (odds ratio: 19.3, 95% confidence interval: 2.91 to 128). Lateral or central callus had a significantly larger risk of fracture than fusiform, cylindrical, or concave callus.

Radiological monitoring of the shape of the callus during distraction is important to prevent early and late fracture of lengthened limbs in patients with ACH or HCH. In patients with thin callus formation, some measures to stimulate bone formation should be considered as early as possible.

Cite this article: Bone Joint J 2014;96-B:1269–73.