Original Article
A Biomechanical Comparison of 2 Transosseous-Equivalent Double-Row Rotator Cuff Repair Techniques Using Bioabsorbable Anchors: Cyclic Loading and Failure Behavior

https://doi.org/10.1016/j.arthro.2009.02.023Get rights and content

Purpose

A novel double-row configuration was compared with a traditional double-row configuration for rotator cuff repair.

Methods

In 10 matched-pair sheep shoulders in vitro repair was performed with either a double-row technique with corkscrew suture anchors for the medial row and insertion anchors for the lateral row (group A) or a double-row technique with a new tape-like suture material with insertion anchors for both the medial and lateral rows (group B). Each specimen underwent cyclic loading from 10 to 150 N for 100 cycles, followed by unidirectional failure testing. Gap formation and strain within the repair area for the first and last cycles were analyzed with a video digitizing system, and stiffness and failure load were determined from the load-elongation curve.

Results

The results were similar for the 2 repair types. There was no significant difference between the ultimate failure loads of the 2 techniques (421 ± 150 N in group A and 408 ± 66 N in group B, P = .31) or the stiffness of the 2 techniques (84 ± 26 N/mm in group A and 99 ± 20 N/mm in group B, P = .07). In addition, gap formation was not different between the repair types. Strain over the repair area was also not different between the repair types.

Conclusions

Both tested rotator cuff repair techniques had high failure loads, limited gap formation, and acceptable strain patterns. No significant difference was found between the novel and conventional double-row repair types.

Clinical Relevance

Two double-row techniques—one with corkscrew suture anchors for the medial row and insertion anchors for the lateral row and one with insertion anchors for both the medial and lateral rows—provided excellent biomechanical profiles at time 0 for double-row repairs in a sheep model. Although the sheep model may not directly correspond to in vivo conditions, all–insertion anchor double-row constructs are worthy of further investigation.

Section snippets

Methods

In this study 20 Merino sheep shoulders (10 pairs; mean age, 1 year) were harvested and frozen at −20°C before testing. Each specimen was allowed to thaw before dissection, surgical site preparation, and testing. The infraspinatus muscle is the most developed rotator cuff muscle in the sheep and has been used in prior studies for evaluation of anchoring constructs.18, 22, 23 The infraspinatus tendon and humeral attachment were carefully dissected and isolated, and the remaining rotator cuff

Cyclic Loading

There were no statistically significant differences noted between group A and group B during the cyclic loading test (Table 1). Gap formation was not significantly different between the 2 groups in either the first or last cycle. Strain recorded over the repair area was also not significantly different between the 2 groups in either the first or last cycle. For both group A and group B, all specimens survived the cyclic loading testing without obvious defect or deformity.

Tensile Testing to Failure

Overall, the results

Discussion

There were no major statistical differences between the novel stitch configuration using 4 insertion anchors and the conventional TOE double-row construct using 2 suture anchors and 2 insertion anchors. Therefore our initial hypothesis must be rejected.

It has been suggested that the suture-tendon interface remains the most likely site of failure of rotator cuff repair.26 Indeed, in our study 19 of 20 specimens failed at the tendon-suture interface. Multiple studies have concluded that

Conclusions

Both tested rotator cuff repair techniques had high failure loads, limited gap formation, and acceptable strain patterns. No significant difference was found between the novel and conventional double-row repair types.

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    Supported by Arthrex, Naples, Florida. The authors report no conflict of interest.

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