The magnetically controlled growing rod (MCGR) system allows growth maintenance without the risk of anaesthesia, implant and wound complications associated with repeated surgeries. This is a medium-term report of the complications of MCGR from a multicentre study.

Twenty-six patients from 6 spine institutes that are part of a multicentre study with prospectively collected data of minimum 24 months follow-up were assessed. Pre-operative, immediate post-operative and most recent spine radiographs were reviewed to measure the Cobb angle and the rod lengthening distance. The causes and any associated risk factors for re-operations were examined.

Eleven patients required re-operation within the follow-up period, with a mean time to re-operation of 17 months after the initial surgery. Five were due to failure of rod distractions; 3 were due to failure of proximal foundation implants; 2 were due to rod breakage; and one case of superficial wound infection with failure of proximal fixation. Proximal junctional kyphosis occurred in 5 patients. Three had proximal anchor dislodgement and all five constructs were revised.

This is the largest series with the longest follow-up to date. Our series show that the perception that using MCGR may reduce the frequency of re-operations may not be entirely true. This is the first report to examine the need for re-operation after MCGR implantation, and highlights the inherent risks of any surgical treatment in this group of patients despite the advantages of this new implant. Longer-term studies and comparisons with traditional growing rods are required.

Summary

Silver nanoparticles improve the tensile property of the repaired Achilles tendon by modulating the synthesis and deposition of collagen. This makes silver nanoparticles a potential drug for tendon healing process with less undesirable side effect.

Introduction: Collagen type X is secreted by hypertrophic chondrocytes during fracture repair. Its precise role is uncertain. This study uses a knockout mouse model in which the collagen X gene is removed to examine its function.

Method: Bilateral femoral fractures were created in type X collagen knockout mice (mutant) and normal mice (wild type), and were stabilized using an external fixator. The mice were sacrificed 7, 10, 14, 21, 28 and 60 days after fracture. Fracture healing was followed by x-rays, histology, gene expression studies, immuno-histochemistry and mechanical testing.

Results: In the mutant mice, bony union was delayed, there was abnormal persistence of aggrecan up to 60 days after fracture. Histology reviewed amorphous acellular areas surrounded by osteoclasts at 21 and 28 days, while mechanical testing revealed that at 14 days after fracture, mutant callus was stiffer than the wild type, but the trend is reversed at 28 and 60 days.

Discussion: This study contributes to the understanding of the basic mechanisms involved in fracture repair. The data suggest that collagen type X plays a significant role in bone remodeling during fracture healing. Its absence results in delayed union and abnormalities within the fracture callus.