Repair of lesser tuberosity osteotomy for shoulder arthroplasty: biomechanical evaluation of the Backpack and Dual Row techniques

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• 作者：Daniel S. Heckman MD ; ^a ; ^{dsheckman11@yahoo.com} ; Stephen A. Hoover MD^a ; Paul S. Weinhold PhD^a ; Jeffrey T. Spang MD^a ; R. Alexander Creighton MD^a
• 关键词：Shoulder arthroplasty ; lesser tuberosity ; subscapularis ; osteotomy ; repair
• 刊名：Journal of Shoulder and Elbow Surgery
• 出版年：2011
• 出版时间：April 2011
• 年：2011
• 卷：20
• 期：3
• 页码：491-496
• 全文大小：688 K

文摘

Background

Subscapularis dysfunction following total shoulder arthroplasty can result in permanent loss of function. The lesser tuberosity osteotomy (LTO) has been proposed as a method which utilizes bone-to-bone healing to improve subscapularis function. This study evaluates the biomechanical properties of two described techniques for LTO repair. We hypothesized that a Dual Row repair would be stronger and demonstrate less cyclic displacement than a Backpack repair.

Materials and methods

Ten matched pairs of cadaveric humeri were dissected, leaving the subscapularis intact, and a lesser tuberosity osteotomy was performed. Matched shoulders were randomized to either a Backpack repair or a Dual Row repair. Repairs were subjected to cyclic loading to 180 N for 500 cycles, followed by ramp-up loading to ultimate failure. Clinical failure was defined as displacement >5 mm after 500 cycles.

Results

Displacement after 500 cycles was significantly greater for the Backpack repair (6.9 mm) than for the Dual Row repair (4.6 mm) (P = .007). Most displacement occurred on the first cycle (Backpack, 4.6 mm; Dual Row, 2.1mm) (P < .001). There was a trend toward a higher clinical failure rate for the Backpack repair (8/10) than the Dual Row repair (3/10). Ultimate tensile strength was significantly greater for the Dual Row repair (632.3 N) than for the Backpack repair (510.9 N) (P = .01).

Conclusion

The Dual Row technique is significantly stronger and demonstrates less cyclic displacement than the Backpack technique. Clinical studies are needed to determine the impact of LTO repair technique on subscapularis function following shoulder arthroplasty.