Martínez Gino S, Baar Alejandro Z, Ibañez Angélica L, Vergara Pamela G, Carmona Maximiliano C, Drago Sebastián P
Pontificia Universidad Católica de Chile, Santiago de, Chile.
J Pediatr Orthop. 2014 Mar;34(2):208-12. doi: 10.1097/BPO.0000000000000101.
Different techniques for gradual correction of angular deformities of lower limbs exist. Long-term behavior of the growth plate after hemiepiphysiodesis is not yet well understood. We assessed the restoration of normal physeal activity in New Zealand rabbits, after transitory hemiepiphysiodesis, using screws and nonabsorbable filament.
We performed a lateral distal femoral epiphysiodesis using nonabsorbable filament and screws, in the right knees of 14 New Zealand male rabbits, aged 11 weeks. Two groups were created: in group 1, the suture was cut after 1 month, and in group 2 it was left uncut. Simple plain radiographs were taken at the beginning and at 4, 8, and 12 weeks of follow-up to evaluate lower limb deformity rate and femoral length. The left knee of each rabbit served as controls. Angular deformity and femoral length were compared between the groups.
Eleven rabbits completed the protocol. The control group had no modification in lower limb mechanical axis. On the fourth week, all operated limbs had a significant valgus tibiofemoral angle variation (mean 24 degrees, P<0.05). When the filament was cut, there was complete restoration of the mechanical axis. When the filament was kept, tibiofemoral angle increased its valgus deformity until the eighth week (mean 32 degrees) without changes thereafter. The final femoral length was shorter in group 2 compared with the other 2 groups (P<0.05), whereas group 1 was slightly longer than the control group (P>0.05).
Lateral distal femoral hemiepiphysiodesis with nonabsorbable filament resulted in a valgus deformity on the femur. Once the filament is cut, the femur can restore its normal alignment, while maintaining longitudinal growth. Keeping the physeal tether increases the valgus achieved during the first 8 weeks, and remained stable throughout the study, shortening the bone.
This is an effective alternative for the correction of angular limb deformities that maintains physeal function and may be useful for orthopedic surgeons. It could also represent an adequate model for the study of rebound effect.
存在多种用于下肢角状畸形逐步矫正的技术。半骨骺阻滞术后生长板的长期行为尚未完全明确。我们使用螺钉和不可吸收丝线，评估了新西兰兔暂时性半骨骺阻滞后正常骨骺活动的恢复情况。
对14只11周龄的新西兰雄性兔的右膝进行外侧股骨远端骨骺阻滞，使用不可吸收丝线和螺钉。分为两组：第1组在1个月后剪断缝线，第2组不剪断缝线。在随访开始时以及随访4周、8周和12周时拍摄简单的X线平片，以评估下肢畸形率和股骨长度。每只兔子的左膝作为对照。比较两组之间的角状畸形和股骨长度。
11只兔子完成了实验方案。对照组下肢机械轴无改变。在第4周时，所有手术肢体的胫股角均有显著的外翻角度变化（平均24度，P<0.05）。当剪断丝线时，机械轴完全恢复。当保留丝线时，胫股角的外翻畸形持续增加至第8周（平均32度），此后无变化。与其他两组相比，第2组的最终股骨长度较短（P<0.05），而第1组略长于对照组（P>0.05）。
使用不可吸收丝线进行外侧股骨远端半骨骺阻滞会导致股骨外翻畸形。一旦剪断丝线，股骨可恢复正常对线，同时保持纵向生长。保留骨骺束缚会增加前8周的外翻程度，并在整个研究过程中保持稳定，导致骨骼缩短。
这是矫正肢体角状畸形的一种有效替代方法，可维持骨骺功能，对骨科医生可能有用。它也可能是研究反弹效应的一个合适模型。
