Focal osteolysis and corrosion at the junction of Precice Stryde intramedullary lengthening device

Aims This study aims to enhance understanding of clinical and radiological consequences and involved mechanisms that led to corrosion of the Precice Stryde (Stryde) intramedullary lengthening nail in the post market surveillance era of the device. Between 2018 and 2021 more than 2,000 Stryde nails have been implanted worldwide. However, the outcome of treatment with the Stryde system is insufficiently reported. Methods This is a retrospective single-centre study analyzing outcome of 57 consecutive lengthening procedures performed with the Stryde nail at the authors’ institution from February 2019 until November 2020. Macro- and microscopic metallographic analysis of four retrieved nails was conducted. To investigate observed corrosion at telescoping junction, scanning electron microscopy (SEM) and energy dispersive x-ray spectroscopy (EDX) were performed. Results Adjacent to the nail’s telescoping junction, osteolytic changes were observed in bi-planar radiographs of 20/57 segments (35%) after a mean of 9.5 months (95% confidence interval 7.2 to 11.9) after surgery. A total of 8/20 patients with osseous alterations (40%) reported rest and ambulation pain of the lengthened segment during consolidation. So far, 24 Stryde nails were retrieved and in 20 (83%) macroscopic corrosion was observed at the nail’s telescoping junction. Before implant removal 11/20 radiographs (55%) of lengthened segments with these 20 nails revealed osteolysis. Implant retrieval analysis by means of SEM showed pitting and crevice corrosion. EDX detected chromium as the main metallic element of corrosion. Conclusion Patients are exposed to the risk of implant-related osteolysis of unclear short- and long-term clinical consequences. The authors advocate in favour of an early implant removal after osseous consolidation. Cite this article: Bone Joint Res 2021;10(7):425–436.

Avascular Necrosis of the Intermedioradial Carpal Bone in a 6-Month-Old Dog

A 6-month-old neutered male dog presented for investigation of right thoracic limb lameness of 6-week duration following an acute injury. Radiography and computed tomography revealed focal osteolysis of the intermedioradial carpal bone. Histopathology of the bone revealed osteonecrosis, bone resorption, fibrous proliferation and new bone formation suggestive of avascular necrosis. Pancarpal arthrodesis was performed to stabilize the carpus and resulted in resolution of lameness and return to normal exercise. Avascular necrosis of carpal bones is rare and unreported in skeletally immature dogs. The imaging and histopathological changes in this dog's intermedioradial carpal bone bear strong similarity to Legg-Calvé-Perthes disease and the two presentations may have a similar traumatic vascular pathology.

Experimental Osteonecrosis of the Lunate

Is lunate collapse in Kienböck’s disease a consequence of spontaneous revascularization, leading to focal osteolysis? A literature review of osteonecrosis in other locations such as the femoral head and bone allografts showed clearly that the loss of mechanical integrity is due to cellular processes which follow the spontaneous restoration of blood supply. We found no evidence in the literature that the lunate has been shown to be avascular at the time of collapse. On the contrary, increased osteoclastic activity has been reported. We excised and reimplanted the lunate in two monkeys, and found spontaneous revascularization, leading to increased osteoblastic activity. Other parts of the bone were destroyed by osteoclasts, leading to collapse. This histological example suggests that it may be possible to make an analogy with osteonecrosis in other locations. Thus, changes on plain radiography may indicate that the bone is revascularized spontaneously. Before performing operative revascularization of the lunate, one should consider that revascularization is a probable cause for collapse.