Gigi Roy, Hemo Yoram, Danino Baruch, Ovadia Dror, Segev Eitan
Department of Pediatric Orthopedic Surgery, Dana Children's Hospital, Tel Aviv Sourasky Medical Center, affiliated to the Sackler Faculty of Medicine, Tel Aviv University, 6 Weizman Street, 6423906, Tel Aviv, Israel.
Arch Orthop Trauma Surg. 2022 Aug;142(8):1739-1742. doi: 10.1007/s00402-020-03740-9. Epub 2021 Feb 8.
The intramedullary magnetic IM nail enables bone graduated distraction. Proximal femur osteotomies for ante grade IM lengthening nails have a tendency towards varus-procurvatum malalignment. We examined the effect of the level of the osteotomy and of trochanteric versus piriformis entry points on the neck shaft angle (NSA) during lengthening with the PRECICE IM magnetic nail.
A novel parameter, the osteotomy level coefficient (OLC), was introduced as a guide to determine the level of an osteotomy at the proximal femur. The OLC was defined as the ratio between the distances from the tip of the greater trochanter to the osteotomy divided by the full length of the femur. A retrospective review of all femoral lengthening procedures with the PRECICE ante grade IM lengthening nail between 2013 and 2018 was carried out.
31 femurs were lengthened in 30 patients (16 males and 14 females, mean age at surgery years 17.1. The average amount of lengthening was 4.4 cm. Trochanteric entry points were used in 24 femurs, and piriformis entry points in seven femurs. The OLC values ranged from 0.16 to 0.34 (average 0.25). The average follow-up period was 10.15 months. The distraction index average 10.5 days/cm (Range 8.6-11.9), Consolidation index 32.1 days/cm (14.3-51.9). The average post-operative NSA was significantly reduced from 133.5º to 128.5º [t (31) = 5.57, p = 0.000]. There was no correlation between the OLC and the change in the NSAs. The trochanteric entry point showed a greater tendency to reduce the NSA (Mdif = - 6, SD = 4.8) compared to the piriformis entry point (Mdif = - 0.86, SD = 2.27) [t (31) = -3.96, p = 0.001].
Proximal femur lengthening with the PRECICE IM nail significantly reduced the NSA and might cause Varus deformity. The level of osteotomy by OLC did not influence the amount of NSA reduction. The trochanteric entry points have a greater tendency to reduce the NSA compared to the piriformis entry points.
髓内磁性IM钉可实现骨的逐步撑开延长。股骨近端截骨用于顺行髓内延长钉时，有内翻-前凸畸形的倾向。我们研究了截骨水平以及大转子入路与梨状肌入路对使用PRECICE IM磁性钉延长过程中颈干角（NSA）的影响。
引入一个新参数，即截骨水平系数（OLC），作为确定股骨近端截骨水平的指导。OLC定义为从大转子尖端到截骨处的距离与股骨全长的比值。对2013年至2018年间所有使用PRECICE顺行髓内延长钉进行股骨延长手术的病例进行回顾性研究。
30例患者的31根股骨进行了延长（男性16例，女性14例，手术时平均年龄17.1岁）。平均延长量为4.4厘米。24根股骨采用大转子入路，7根股骨采用梨状肌入路。OLC值范围为0.16至0.34（平均0.25）。平均随访期为10.15个月。撑开指数平均为10.5天/厘米（范围8.6 - 11.9），愈合指数为32.1天/厘米（14.3 - 51.9）。术后平均NSA从133.5°显著降至128.5°[t(31) = 5.57，p = 0.000]。OLC与NSA的变化之间无相关性。与梨状肌入路（平均差值=-0.86，标准差=2.27）相比，大转子入路显示出更大的降低NSA的倾向（平均差值=-6，标准差=4.8）[t(31) = -3.96，p = 0.001]。
使用PRECICE IM钉进行股骨近端延长显著降低了NSA，可能导致内翻畸形。通过OLC确定的截骨水平不影响NSA降低的程度。与梨状肌入路相比，大转子入路有更大的降低NSA的倾向。
