Arciero Robert A, Parrino Anthony, Bernhardson Andrew S, Diaz-Doran Vilmaris, Obopilwe Elifho, Cote Mark P, Golijanin Petr, Mazzocca Augustus D, Provencher Matthew T
Department of Orthopaedic Surgery, University of Connecticut Health Center, Farmington, Connecticut, USA
Department of Orthopaedic Surgery, University of Connecticut Health Center, Farmington, Connecticut, USA.
Am J Sports Med. 2015 Jun;43(6):1422-9. doi: 10.1177/0363546515574677. Epub 2015 Mar 20.
Bone loss in anterior glenohumeral instability occurs on both the glenoid and the humerus; however, existing biomechanical studies have evaluated glenoid and humeral head defects in isolation. Thus, little is known about the combined effect of these bony lesions in a clinically relevant model on glenohumeral stability.
HYPOTHESIS/PURPOSE: The purpose of this study was to determine the biomechanical efficacy of a Bankart repair in the setting of bipolar (glenoid and humeral head) bone defects determined via computer-generated 3-dimensional (3D) modeling of 142 patients with recurrent anterior shoulder instability. The null hypothesis was that adding a bipolar bone defect will have no effect on glenohumeral stability after soft tissue Bankart repair.
Controlled laboratory study.
A total of 142 consecutive patients with recurrent anterior instability were analyzed with 3D computed tomography scans. Two Hill-Sachs lesions were selected on the basis of volumetric size representing the 25th percentile (0.87 cm(3); small) and 50th percentile (1.47 cm(3); medium) and printed in plastic resin with a 3D printer. A total of 21 cadaveric shoulders were evaluated on a custom shoulder-testing device permitting 6 degrees of freedom, and the force required to translate the humeral head anteriorly 10 mm at a rate of 2.0 mm/s with a compressive load of 50 N was determined at 60° of glenohumeral abduction and 60° of external rotation. All Bankart lesions were made sharply from the 2- to 6-o'clock positions for a right shoulder. Subsequent Bankart repair with transosseous tunnels using high-strength suture was performed. Hill-Sachs lesions were made in the cadaver utilizing a plastic mold from the exact replica off the 3D printer. Testing was conducted in the following sequence for each specimen: (1) intact, (2) posterior capsulotomy, (3) Bankart lesion, (4) Bankart repair, (5) Bankart lesion with 2-mm glenoid defect, (6) Bankart repair, (7) Bankart lesion with 2-mm glenoid defect and Hill-Sachs lesion, (8) Bankart repair, (9) Bankart lesion with 4-mm glenoid defect and Hill-Sachs lesion, (10) Bankart repair, (11) Bankart lesion with 6-mm glenoid defect and Hill-Sachs lesion, and (12) Bankart repair. All sequences were used first for a medium Hill-Sachs lesion (10 specimens) and then repeated for a small Hill-Sachs lesion (11 specimens). Three trials were performed in each condition, and the mean value was used for data analysis.
A statistically significant and progressive reduction in load to translation was observed after a Bankart lesion was created and with the addition of progressive glenoid defects for each humeral head defect. For medium (50th percentile) Hill-Sachs lesions, there was a 22%, 43%, and 58% reduction in stability with a 2-, 4-, and 6-mm glenoid defect, respectively. For small (25th percentile) Hill-Sachs lesions, there was an 18%, 27%, and 42% reduction in stability with a 2-, 4-, and 6-mm glenoid defect, respectively. With a ≥2-mm glenoid defect, the medium Hill-Sachs group demonstrated significant reduction in translation force after Bankart repair (P < .01), and for the small Hill-Sachs group, a ≥4-mm glenoid defect was required to produce a statistical decrease (P < .01) in reduction force after repair.
Combined glenoid and humeral head defects have an additive and negative effect on glenohumeral stability. As little as a 2-mm glenoid defect with a medium-sized Hill-Sachs lesion demonstrated a compromise in soft tissue Bankart repair, while small-sized Hill-Sachs lesions showed compromise of soft tissue repair with ≥4-mm glenoid bone loss.
Bipolar bony lesions of the glenoid and humeral head occur frequently together in clinical practice. Surgeons should be aware that the combined defects and glenoid bone loss of 2 to 4 mm or approximately 8% to 15% of the glenoid could compromise Bankart repair and thus may require surgical strategies in addition to traditional Bankart repair alone to optimize stability.
肩肱关节前向不稳时，肩胛盂和肱骨头均会出现骨质流失；然而，现有的生物力学研究都是单独评估肩胛盂和肱骨头的缺损情况。因此，在临床相关模型中，对于这些骨损伤对肩肱关节稳定性的综合影响知之甚少。
假设/目的：本研究的目的是通过对142例复发性肩前不稳患者进行计算机生成的三维（3D）建模，确定在双极（肩胛盂和肱骨头）骨缺损情况下Bankart修复术的生物力学效果。无效假设是，在软组织Bankart修复术后，增加双极骨缺损对肩肱关节稳定性无影响。
对照实验室研究。
对142例连续的复发性前向不稳患者进行3D计算机断层扫描分析。根据体积大小选择两个Hill-Sachs损伤，分别代表第25百分位数（0.87 cm³；小）和第50百分位数（1.47 cm³；中），并使用3D打印机用塑料树脂打印出来。在一个允许6个自由度的定制肩部测试装置上对21具尸体肩部进行评估，在肩肱关节外展60°和外旋60°时，以2.0 mm/s的速度将肱骨头向前平移10 mm，同时施加50 N的压缩载荷，测定所需的力。所有Bankart损伤均从右肩的2点至6点位置锐性制造。随后使用高强度缝线通过骨隧道进行Bankart修复。利用3D打印机精确复制的塑料模具在尸体上制造Hill-Sachs损伤。对每个标本按以下顺序进行测试：（1）完整状态，（2）后关节囊切开，（3）Bankart损伤，（4）Bankart修复，（5）伴有2-mm肩胛盂缺损的Bankart损伤，（6）Bankart修复，（7）伴有2-mm肩胛盂缺损和Hill-Sachs损伤的Bankart损伤，（8）Bankart修复，（9）伴有4-mm肩胛盂缺损和Hill-Sachs损伤的Bankart损伤，（10）Bankart修复，（11）伴有6-mm肩胛盂缺损和Hill-Sachs损伤的Bankart损伤，（12）Bankart修复。所有序列先用于中等大小的Hill-Sachs损伤（10个标本），然后重复用于小的Hill-Sachs损伤（11个标本）。每种情况进行3次试验，取平均值进行数据分析。
在制造Bankart损伤后以及针对每个肱骨头缺损增加渐进性肩胛盂缺损时，观察到平移负荷出现统计学上显著且渐进性的降低。对于中等（第50百分位数）Hill-Sachs损伤，伴有2-mm、4-mm和6-mm肩胛盂缺损时，稳定性分别降低22%、43%和58%。对于小（第25百分位数）Hill-Sachs损伤，伴有2-mm、4-mm和6-mm肩胛盂缺损时，稳定性分别降低18%、27%和42%。对于中等Hill-Sachs组，当肩胛盂缺损≥2-mm时，Bankart修复术后平移力显著降低（P <.01）；对于小Hill-Sachs组，需要≥4-mm的肩胛盂缺损才能使修复后复位力出现统计学上的降低（P <.01）。
肩胛盂和肱骨头联合缺损对肩肱关节稳定性有累加的负面影响。对于中等大小的Hill-Sachs损伤，仅2-mm的肩胛盂缺损就表明软组织Bankart修复受到影响，而对于小的Hill-Sachs损伤，当肩胛盂骨质流失≥4-mm时，软组织修复受到影响。
在临床实践中，肩胛盂和肱骨头的双极骨损伤经常同时出现。外科医生应意识到，联合缺损以及肩胛盂2至4 mm或约占肩胛盂8%至15%的骨质流失可能会影响Bankart修复，因此可能需要除传统的单独Bankart修复之外的手术策略来优化稳定性。
