Center of Experimental Orthopaedics, Saarland University, Homburg, Germany.
Am J Sports Med. 2012 Apr;40(4):828-36. doi: 10.1177/0363546511430376. Epub 2012 Jan 5.
Marrow stimulation techniques such as subchondral drilling are clinically important treatment options for symptomatic small cartilage defects. Little is known about whether they induce deleterious changes in the subchondral bone.
Subchondral drilling induces substantial alterations of the microarchitecture of the subchondral bone that persist for a clinically relevant postoperative period in a preclinical large animal model.
Controlled laboratory study.
Standardized full-thickness chondral defects in the medial femoral condyles of 19 sheep were treated by subchondral drilling. Six months postoperatively, the formation of cysts and intralesional osteophytes was evaluated. A standardized methodology was developed to segment the ovine subchondral unit into reproducible volumes of interest (VOIs). Indices of bone structure were determined by micro-computed tomography (micro-CT).
Analysis of the microarchitecture revealed the absence of zonal stratification in the ovine subarticular spongiosa, permitting an unimpeded and simultaneous analysis of the entire subchondral trabecular network. Subchondral drilling led to the formation of subchondral bone cysts (63%) and intralesional osteophytes (26%). Compared with the adjacent unaffected subchondral bone, drilling induced significant alterations in nearly all parameters for the microarchitecture of the subchondral bone plate and the subarticular spongiosa, most importantly in bone volume, bone surface/volume ratio, trabecular thickness, separation, pattern factor, and bone mineral density (BMD) (all P ≤ .01).
The data show that the ovine subchondral bone can be reliably evaluated using micro-CT with standardized VOIs. We report that subchondral drilling deteriorates the microarchitecture both of the subchondral bone plate and subarticular spongiosa and decreases BMD. These results suggest that the entire osteochondral unit is altered after drilling for an extended postoperative period.
The subchondral bone remains fragile after subchondral drilling for longer durations than previously expected. Further evaluations of structural subchondral bone parameters of patients undergoing marrow stimulation are warranted.
骨髓刺激技术，如软骨下钻孔，是治疗有症状的小软骨缺损的重要临床选择。但对于这些技术是否会引起软骨下骨的有害变化知之甚少。
软骨下钻孔会导致软骨下骨微观结构发生实质性改变，在临床相关的术后期间，在大型动物模型中持续存在。
对照实验室研究。
在 19 只绵羊的内侧股骨髁的标准全层软骨缺损处进行软骨下钻孔。术后 6 个月，评估囊肿和病灶内骨赘的形成。开发了一种标准化方法，将羊的软骨下单位分割成可重复的感兴趣体积（VOI）。通过微计算机断层扫描（micro-CT）确定骨结构指数。
对微观结构的分析显示，羊的软骨下松质骨中不存在带层结构，允许对整个软骨下小梁网络进行无障碍和同时分析。软骨下钻孔导致软骨下骨囊肿（63%）和病灶内骨赘（26%）的形成。与相邻未受影响的软骨下骨相比，钻孔导致软骨下骨板和软骨下松质骨微观结构的几乎所有参数发生显著改变，最重要的是骨体积、骨表面/体积比、小梁厚度、分离、形态因子和骨矿物质密度（BMD）（均 P≤0.01）。
数据表明，使用具有标准化 VOI 的 micro-CT 可以可靠地评估羊的软骨下骨。我们报告说，软骨下钻孔会恶化软骨下骨板和软骨下松质骨的微观结构，并降低 BMD。这些结果表明，在钻孔后的延长术后期间，整个骨软骨单位都会发生改变。
软骨下钻孔后的软骨下骨在比预期更长的时间内仍然脆弱。需要进一步评估接受骨髓刺激的患者的结构性软骨下骨参数。
