Specialty Update: What’s New in Shoulder and Elbow Surgery (2004)
Shoulder Rotator Cuff Basic Science Kelly compared the muscle-firing patterns in both symptomatic and asymptomatic patients who had two-tendon rotator cuff tears. Asymptomatic patients demonstrated increased firing of the intact subscapularis, whereas symptomatic patients continued to rely on torn rotator cuff tendons and scapular muscle substitution, resulting in compromised function. Kalandiak compared the in vivo kinematics of painless shoulders that had massive rotator cuff tears with those of normal shoulders with use of cinefluoroscopy. Only one patient demonstrated normal "ball and socket" kinematics; most demonstrated increased scapulothoracic motion during initial forward elevation. The mean active forward elevation was 129° when performed against no resistance but only 86° when performed against resistance. Rubino studied the progression of fatty infiltration by harvesting the supraspinatus muscle bilaterally at various timeintervals following unilateral surgical detachment of that tendon in a rabbit model. A consistent decrease in muscle weight was noted when detached specimens were compared with intact specimens.
Fatty infiltration was evident as early as six weeks after detachment and increased over time as a percentage of muscle volume (p = 0.002). Schlegel compared the modified Mason-Allen stitch with a horizontal mattress stitch in a sheep model to determine the effect on tendon-healing to bone. Subsequent biomechanical and histological testing demonstrated similar stiffness and loads to failure and normal-appearing tendon-tobone insertions. St. Pierre compared three different suturerepair techniques in a human cadaver model. The modified Mason-Allen and double-mattress techniques had higher ultimate loads to failure than did the single-horizontal-mattress technique when used with suture anchors. Boswell compared bioabsorbable screw-and-washer fixation with various suture-anchor repairs for rotator cuff fixation in a bovine model. The study demonstrated that 5-mm gap formation occurred later in association with the bioabsorbable screw-and-washer method than it did in association with any suture-anchor repair method, including a technique involving the use of single-loaded anchors with modified Mason-Allen sutures. Tasto used a bovine model to demonstrate that the depth of insertion of suture anchors influences their ultimate load strength and mode of failure. Countersunk anchors had greater ultimate load strength to failure than did anchors that were placed proud or level with the cortical surface.
In addition, no sutures in the countersunk-sutureanchor group failed during cyclical loading. Hawkins compared the accuracy of physical examination alone with that of physical examination coupled with magnetic resonance imaging for the diagnosis of rotator cuff tears. Prospective data were collected on 299 patients who underwent rotator cuff surgery, 148 of whom had ancillary magnetic resonance imaging data. The positive predictive values for the diagnosis of a full-thickness tear on physical... (download full pdf article)
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