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Biomechanical Evaluation of Arthroscopic Rotator Cuff Repairs: Double-Row Compared with Single-Row Fixation

Ma, C. Benjamin MD; Comerford, Lyn MSc; Wilson, Joseph MD; Puttlitz, Christian M. PhD

Journal of Bone & Joint Surgery - American Volume: February 2006 - Volume 88 - Issue 2 - p 403–410
doi: 10.2106/JBJS.D.02887
Scientific Articles
Supplementary Content

Background: Recent studies have shown that arthroscopic rotator cuff repairs can have higher rates of failure than do open repairs. Current methods of rotator cuff repair have been limited to single-row fixation of simple and horizontal stitches, which is very different from open repairs. The objective of this study was to compare the initial cyclic loading and load-to-failure properties of double-row fixation with those of three commonly used single-row techniques.

Methods: Ten paired human supraspinatus tendons were split in half, yielding four tendons per cadaver. The bone mineral content at the greater tuberosity was assessed. Four stitch configurations (two-simple, massive cuff, arthroscopic Mason-Allen, and double-row fixation) were randomized and tested on each set of tendons. Specimens were cyclically loaded between 5 and 100 N at 0.25 Hz for fifty cycles and then loaded to failure under displacement control at 1 mm/sec. Conditioning elongation, peak-to-peak elongation, ultimate tensile load, and stiffness were measured with use of a three-dimensional tracking system and compared, and the failure type (suture or anchor pull-out) was recorded.

Results: No significant differences were found among the stitches with respect to conditioning elongation. The mean peak-to-peak elongation (and standard error of the mean) was significantly lower for the massive cuff (1.1 ± 0.1 mm) and double-row stitches (1.1 ± 0.1 mm) than for the arthroscopic Mason-Allen stitch (1.5 ± 0.2 mm) (p < 0.05). The ultimate tensile load was significantly higher for double-row fixation (287 ± 24 N) than for all of the single-row fixations (p < 0.05). Additionally, the massive cuff stitch (250 ± 21 N) was found to have a significantly higher ultimate tensile load than the two-simple (191 ± 18 N) and arthroscopic Mason-Allen (212 ± 21 N) stitches (p < 0.05). No significant differences in stiffness were found among the stitches. Failure mechanisms were similar for all stitches. Rotator cuff repairs in the anterior half of the greater tuberosity had a significantly lower peak-to-peak elongation and higher ultimate tensile strength than did repairs on the posterior half.

Conclusions: In this in vitro cadaver study, double-row fixation had a significantly higher ultimate tensile load than the three types of single-row fixation stitches. Of the single-row fixations, the massive cuff stitch had cyclic and load-to-failure characteristics similar to the double-row fixation. Anterior repairs of the supraspinatus tendon had significantly stronger biomechanical behavior than posterior repairs.

Clinical Relevance: The results of this study support the concept that double-row fixation can improve the initial fixation strength of arthroscopic rotator cuff repairs.

1 Department of Orthopaedic Surgery, University of California, San Francisco, 500 Parnassus Avenue, MU 320W, San Francisco, CA 94143-0728. E-mail address for C.B. Ma: maben@orthosurg.ucsf.edu

2 Orthopaedic Biomechanics Laboratory, San Francisco General Hospital, 1001 Potrero Avenue, #3A36, San Francisco, CA 94110

3 Department of Mechanical Engineering, Colorado State University, 1374 Campus Delivery, Fort Collins, CO 80523

Copyright 2006 by The Journal of Bone and Joint Surgery, Incorporated
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