Objective This study aimed to evaluate implant-induced osteoporosis (IIO) development in toy breed dogs treated using internal fixation with digital radiographs as the index of pixel values.

Study Design There were 226 cases (236 limbs) of toy breed dogs with radial–ulnar fractures. Pixel values were measured on radiographs immediately, 2 weeks and 1 to 12 months after surgery. The ratio of pixel values (PVR) represented the bone mineral areal density based on the humeral condyle in the same image. The dogs were grouped based on the fixation methods, age and status of destabilization.

Results There was a significant decrease in the PVR at 1 to 12 months postoperatively for all cases. There were not any significant differences in PVR of antebrachial fractures between those repaired with plates using locking head screws, cortex screws or a combination of locking and cortex screws. Implant-induced osteoporosis persisted at 1 to 12 months postoperatively in dogs aged ≧6 months, while the PVR increased after 3 months in dogs aged <6 months. Based on the destabilization method, there was a significant increase in the PVR at 3 months in the plate removal group.

Conclusion This study suggests that IIO occurs in small dogs treated with plates and screws. Moreover, patients aged < 6 months showed an early postoperative recovery of bone mineral areal density. Further, screw and plate removal could contribute to the recovery of bone mineral areal density.

目的 本研究旨在评估使用数字射线照片作为像素值指标的内固定治疗玩具犬的植入物诱发的骨质疏松症 (IIO) 的发展。

研究设计 有 226 例（236 条肢体）玩具犬患有桡尺骨骨折。在手术后立即、2 周和 1 至 12 个月后在 X 光片上测量像素值。像素值比 (PVR) 表示基于同一图像中肱骨髁的骨矿物质面积密度。根据固定方法、年龄和不稳定状态对狗进行分组。

结果 所有病例术后 1 至 12 个月的 PVR 均显着降低。使用锁定螺钉、皮质螺钉或锁定螺钉和皮质螺钉组合使用钢板修复的前臂骨折 PVR 没有任何显着差异。植入物诱导的骨质疏松症在 ≥ 6 个月的狗中持续存在术后 1 至 12 个月，而在小于 6 个月的狗中，PVR 在 3 个月后增加。基于去稳定法，钢板去除组在3个月时PVR有显着增加。

结论 这项研究表明 IIO 发生在用钢板和螺钉治疗的小型犬身上。此外，<6 个月的患者术后骨矿物质密度恢复较早。此外，螺钉和钢板的移除可能有助于骨矿物质面密度的恢复。