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
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
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.