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Clinical Research: Shoulder & Elbow Surgery Selected Abstracts 2008-2009 |
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FACULTY
John M. Fenlin, Jr., MD
Barbara G. Frieman, MD
Mark D. Lazarus, MD
Gerald R. Williams, Jr., MD
Matthew L. Ramsey, MD
Charles Getz, MD
Eccentric reaming in total shoulder arthroplasty: a cadaveric study.
Gillepsie R, Lyons R, Lazarus M.
Orthopedics. 2009 Jan;32(1):21.
Posterior glenoid bone loss often is seen in association with glenohumeral osteoarthritis. Many different techniques have been proposed to account for this bone loss during total shoulder arthroplasty, the most popular being eccentric anterior reaming. However, the amount of correction that can be achieved has not been been well quantified. The purpose of this study was to define the amount of eccentric posterior glenoid wear that can be corrected by anterior glenoid reaming. Eight cadaveric scapulae were studied. Simulations of posterior glenoid wear in 5 degrees increments were performed on each scapula. The specimens were then eccentrically reamed to correct the deformity. Anteroposterior width, superior-inferior height, and the best-fit pegged glenoid prosthesis size were measured. Anterior reaming to correct a 10 degrees posterior defect resulted in a decrease in anteroposterior glenoid diameter from 26.7+/-2.5 mm to 23.8+/-3.1 mm (P=.006). In 4 of 8 specimens, placing a glenoid prosthesis was not possible after correcting a 15 degrees deformity because of inadequate bony support (N=2), peg penetration (N=1) or both (N=1). A 20 degrees deformity was correctable in 2 of 8 specimens and only after downsizing the glenoid component. Anterior glenoid reaming to correct eccentric posterior wear of >10 degrees results in significant narrowing of the anteroposterior glenoid width. A 15 degrees deformity has only a 50% chance of successful correction by anterior, eccentric reaming. Orthopedic surgeons need to be cognizant of this in their preoperative planning for total shoulder arthroplasty.
Mechanical properties of the long-head of the biceps tendon are altered in the presence of rotator cuff tears in a rat model.
Peltz CD, Perry SM, Getz CL, Soslowsky LJ.
J Orthop Res. 2009 Mar;27(3):416-20.
Rotator cuff tears are disabling conditions that result in changes in joint loading and functional deficiencies. Clinically, damage to the long-head of the biceps tendon has been found in conjunction with rotator cuff tears, and this damage is thought to increase with increasing tear size. Despite its importance, controversy exists regarding the optimal treatment for the biceps. An animal model of this condition would allow for controlled studies to investigate the etiology of this problem and potential treatment strategies. We created rotator cuff tears in the rat model by detaching single (supraspinatus) and multiple (supraspinatus + infraspinatus or supraspinatus + subscapularis) rotator cuff tendons and measured the mechanical properties along the length of the long-head of the biceps tendon 4 and 8 weeks following injury. Cross-sectional area of the biceps was increased in the presence of a single rotator cuff tendon tear (by approximately 150%), with a greater increase in the presence of a multiple rotator cuff tendon tear (by up to 220%). Modulus values decreased as much as 43 and 56% with one and two tendon tears, respectively. Also, multiple tendon tear conditions involving the infraspinatus in addition to the supraspinatus affected the biceps tendon more than those involving the subscapularis and supraspinatus. Finally, biceps tendon mechanical properties worsened over time in multiple rotator cuff tendon tears. Therefore, the rat model correlates well with clinical findings of biceps tendon pathology in the presence of rotator cuff tears, and can be used to evaluate etiology and treatment modalities.
Arthroscopic reduction and fixation with suture-bridge technique for displaced or comminuted greater tuberosity fractures.
Song HS, Williams GR Jr.
Arthroscopy. 2008 Aug;24(8):956-60.
The arthroscopic suture-bridge technique (transosseous equivalent technique) was initially described for increasing the footprint size during arthroscopic rotator cuff repair. We describe a method in which the same principles are used to fix a displaced or comminuted greater tuberosity fracture. The technique involves reducing the displaced fragment with two medially placed, trans-tendinous anchors and compressing the greater tuberosity using the sutures from these medial anchors in two laterally placed anchors. The two medial anchors are inserted through the junction of the cuff and fragment. The anchor driver can be used as a joystick to reduce the fragment into position. One suture limb of each anchor is passed back through the tendon 5 mm from the original anchor insertion point in the tendon. With the scope in the subacromial space, the sutures from the medial anchors are tied in a mattress configuration. The four suture ends are passed distally over the greater tuberosity and incorporated into two PushLock anchors (4.5 mm; Arthrex, Naples, FL) using the suture-bridge technique. The postoperative rehabilitation protocol is similar to that for rotator cuff repairs. |
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