Metcalf M H, Pon J D, Harryman D T, Loutzenheiser T, Sidles J A
Department of Orthopaedic Surgery, University of Washington, Seattle, USA.
J Shoulder Elbow Surg. 2001 Nov-Dec;10(6):532-8. doi: 10.1067/mse.2001.118411.
Multidirectional instability is not clearly understood. Excessive capsular laxity has been proposed as the key component. However, because ligaments fail to resist humeral head translation until they are tensioned, glenohumeral instability in the mid range of motion cannot be explained by capsuloligamentous pathology alone. Capsulolabral augmentation is designed to increase glenohumeral stability by 2 separate mechanisms: deepening the glenoid concavity and reducing capsular laxity. This is accomplished by shifting the capsule to buttress the glenoid labrum. Hence, the glenolabral concavity in which the humeral head is stabilized by compression throughout the entire range is enhanced. The purposes of this study were to examine glenolabral depth and glenohumeral stability before and after labral augmentation and to measure the effect of diminished capsular laxity on motion in clinically important positions. We compared glenolabral depth, resistance to humeral head displacement, and glenohumeral range of motion before and after capsulolabral augmentation. Glenolabral depth was measured as the lateral displacement of the center of the humeral head translating from the glenoid fossa. We recorded a mean increase in glenoid depth of 1.9 mm inferiorly, 2.0 mm posteroinferiorly, and 0.9 mm posteriorly (P <.02). Resistance to humeral head displacement was measured by use of the stability ratio, defined as the translatory force required to displace the humeral head divided by the force compressing the humeral head into the glenoid fossa. The mean stability ratio was increased by 0.24 inferiorly and 0.24 posteroinferiorly (P <.02). Motion was measured by achieving 30 degrees and 60 degrees elevation in the 0 degrees, 30 degrees, 60 degrees, and 90 degrees planes of elevation and measuring the extent of possible internal rotation for each of these 8 positions when the capsule was tensioned to exert 1000 N-mm of torque. Reduction of internal rotation in these positions was a mean of 15 degrees at 1000 N-mm of torque. This study demonstrates that humeral head stability within the glenolabral fossa is increased by local capsular augmentation. A simultaneous reduction in capsular laxity is achieved, which partially limits glenohumeral motion. Understanding the biomechanical effect of this procedure helps the physician to establish surgical goals and to explain to patients the rationale of why this procedure may be clinically efficacious.
多向不稳定尚未被完全理解。有人提出关节囊过度松弛是关键因素。然而，由于韧带在被拉紧之前无法抵抗肱骨头移位，因此仅靠关节囊韧带病变无法解释运动中程的盂肱关节不稳定。关节盂唇增强术旨在通过两种不同机制增加盂肱关节稳定性：加深关节盂凹度和减少关节囊松弛。这通过将关节囊移位以支撑关节盂唇来实现。因此，在整个运动范围内通过压缩使肱骨头稳定的关节盂唇凹度得以增强。本研究的目的是检查关节盂唇增强术前和术后的关节盂唇深度和盂肱关节稳定性，并测量关节囊松弛度降低对临床重要位置运动的影响。我们比较了关节盂唇增强术前和术后的关节盂唇深度、对肱骨头移位的抵抗力以及盂肱关节活动范围。关节盂唇深度通过测量肱骨头中心从关节盂窝平移的侧向位移来确定。我们记录到关节盂深度平均在下方增加1.9毫米，后下方增加2.0毫米，后方增加0.9毫米（P <.02）。对肱骨头移位的抵抗力通过稳定性比率来测量，稳定性比率定义为使肱骨头移位所需的平移力除以将肱骨头压入关节盂窝的力。平均稳定性比率在下方和后下方分别增加了0.24（P <.02）。通过在0度、30度、60度和90度抬高平面实现30度和60度抬高，并在关节囊被拉紧以施加1000 N - mm扭矩时测量这8个位置中每个位置可能的内旋程度来测量运动。在这些位置，当扭矩为1000 N - mm时，内旋减少平均为15度。本研究表明，通过局部关节囊增强可增加肱骨头在关节盂唇窝内的稳定性。同时实现了关节囊松弛度的降低，这部分限制了盂肱关节的运动。了解该手术的生物力学效应有助于医生确立手术目标，并向患者解释该手术在临床上可能有效的原理。
