Background and purpose — Observing serious adverse events during treatment with the Precice Stryde bone lengthening nail (NuVasive, San Diego, CA, USA), we conducted a nationwide cross-sectional study to report the prevalence of adverse events from all 30 bone segments in 27 patients treated in Denmark. Patients and methods — Radiographs of all bone segments were evaluated regarding radiographic changes in February 2021. We determined the number of bone segments with late onset of pain and/or radiographically confirmed osteolysis, periosteal reaction, or cortical hypertrophy in the junctional area of the nail. Results — In 30 bone segments of 27 patients we observed radiographic changes in 21/30 segments of 20/27 patients, i.e., 19/30 osteolysis, 12/30 periosteal reaction (most often multi-layered), and 12/30 cortical hypertrophy in the area of the junction between the telescoping nail parts. Late onset of pain was a prominent feature in 8 patients. This is likely to be a prodrome to the bony changes. Discoloration (potential corrosion) at the nail interface was observed in multiple removed nails. 15/30 nails were still at risk of developing complications, i.e., were not yet removed. Interpretation — All Stryde nails should be monitored at regular intervals until removal. Onset of pain at late stages of limb lengthening, i.e., consolidation of the regenerate, should warrant immediate radiographic examination regarding osteolysis, periosteal reaction, and cortical hypertrophy, which may be associated with discoloration (potential corrosion) of the nail. We recommend removal of Stryde implants as early as possible after consolidation of the regenerate.

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We investigated if injectable calcium phosphate cement improves primary stability in open-wedge high-tibial osteotomy. A 10 mm open-wedge osteotomy was performed on eight pairs of preserved cadaver tibiae and seven pairs of composite (Sawbone) left tibiae. Osteosynthesis was performed with the Dynafix plate system. The gap resulting from surgery either was filled with 15 g injectable calcium phosphate cement in half the bones or was left untreated. The composite tibiae were loaded at a ramp speed of 20 mm/min up to 20 kN. The cadaver tibiae were exposed to 100 cycles with a maximum compressive force of 2,250 N. After 100 cycles of loading with 2,250 N, the final loaded displacement was 1.2 mm for the cadaver tibiae treated with injectable calcium phosphate cement as compared with 3.6 mm for the empty defects (P = 0.028). All the seven empty defect composite specimens failed prior to 20 kN (median 2.8 kN) as compared with five of the injectable calcium phosphate cement specimens (median 17 kN) (P = 0.005). The injection of injectable calcium phosphate cement following open-wedge osteotomy of the proximal tibia increases the initial stability of the bone as measured by load-to-failure and displacement after cyclic loading. Clinical studies are ongoing to investigate whether injectable calcium phosphate cement also has clinical advantage on wedge healing and stability.

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