Song Sang-Heon, Agashe Mandar, Kim Tae-Young, Sinha Shivam, Park Young-Eun, Kim Seung-Ju, Hong Jin-Ho, Song Sang-Youn, Song Hae-Ryong
Department of Orthopaedic Surgery, Institute for Rare Diseases, Korea University Medical Center, Guro Hospital, Seoul, Korea.
J Pediatr Orthop B. 2012 Mar;21(2):137-45. doi: 10.1097/BPB.0b013e32834f04f3.
Distraction osteogenesis is one of the common procedures for limb lengthening. However, attempts are being made constantly to establish objective guidelines for early and safe removal of a fixator using a sensitive and quantitative measurement technique. Dual-energy X-ray absorptiometry (DEXA) has been evaluated in the past for understanding callus stiffness, and the present study is a step further in this direction. The purpose of this study was to evaluate the correlation between bone mineral density ratio (BMDR) obtained by a DEXA scan and the pixel value ratio (PVR) on plain digital radiographs at each cortex and various callus pathways and callus shapes as described by Ru-Li's classification. A retrospective analysis of 40 tibial segments in 23 patients operated upon for various indications for limb lengthening was carried out. There were 11 male and 12 female patients with a mean age of 18 years. The Ilizarov method was applied after monofocal osteotomy, and distraction and consolidation were monitored using digital radiographs and DEXA scanning. BMDR was positively correlated with PVR, and the optimal BMDR for removal of the fixator was found to be 0.511. PVR of all cortices, except the anterior cortex, showed significant positive correlation with BMDR of the regenerate. There was good correlation between BMDR and PVR in the homogenous or heterogenous pathway according to callus shape and pathway. Thus, this study shows that BMD measurement can provide an objective and noninvasive method for assessing the rate of new bone formation during tibial distraction osteogenesis. It can thus function as an effective adjunct to measure callus stiffness, along with PVR, using digital radiographs, especially in cases in which callus maturation and stiffness is doubtful. Further studies especially dealing with callus progression through the lucent pathway as well as those dealing with regenerate fractures may be needed to conclusively prove the efficacy of this method for measurement of callus maturation.
牵张成骨术是肢体延长的常用手术方法之一。然而，人们一直在尝试通过敏感且定量的测量技术，建立关于早期安全拆除固定器的客观指导原则。过去曾对双能X线吸收法（DEXA）进行评估，以了解骨痂硬度，而本研究在此方向上更进一步。本研究的目的是评估DEXA扫描获得的骨密度比值（BMDR）与普通数字X线片上各皮质、不同骨痂路径及Ru-Li分类所描述的骨痂形状的像素值比值（PVR）之间的相关性。对23例因各种肢体延长适应证接受手术的患者的40个胫骨干段进行了回顾性分析。患者中男性11例，女性12例，平均年龄18岁。采用单焦点截骨术后应用Ilizarov方法，并使用数字X线片和DEXA扫描监测牵张和骨痂形成过程。BMDR与PVR呈正相关，发现拆除固定器的最佳BMDR为0.511。除前皮质外，所有皮质的PVR与再生骨的BMDR均呈显著正相关。根据骨痂形状和路径，在均匀或不均匀路径中BMDR与PVR之间存在良好的相关性。因此，本研究表明，骨密度测量可为评估胫骨牵张成骨过程中新生骨形成速率提供一种客观且无创的方法。因此，它可作为一种有效的辅助手段，与PVR一起，利用数字X线片测量骨痂硬度，尤其是在骨痂成熟度和硬度存疑的情况下。可能需要进一步的研究，特别是针对骨痂通过透亮路径的进展情况以及再生骨折的研究，以最终证明该方法在测量骨痂成熟度方面的有效性。
