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Into-Tunnel Repair vs. Onto-Surface Repair for Rotator Cuff Tears in a Rabbit Model

Into-Tunnel Repair vs. Onto-Surface Repair for Rotator Cuff Tears in a Rabbit Model

Xiaoxi Li, MD, CHINA Peng Shen, MD, CHINA Song Zhao, MD, CHINA Jinzhong Zhao, MD, CHINA

Shanghai Sixth People’s Hospital, Shanghai, CHINA


2019 Congress   Paper Abstract   2019 Congress   Not yet rated

 

Anatomic Location

Anatomic Structure

Diagnosis / Condition

Sports Medicine

Treatment / Technique


Summary: The into-tunnel repair technique transforms the process of the tendon after rotator cuff repair, which in turn results in a better biomechanical construct.


Background

Clinically, onto-surface repair is commonly used for rotator cuff tears. The retear rate after rotator cuff repair (RCR) is relatively high, with failure occurring mostly at the tendon-bone connection site. For anterior cruciate ligament (ACL) reconstruc- tion, into-tunnel reconstruction is commonly employed. The retear rate after ACL reconstruction is relatively low, with retears sel- dom occurring at the tendon-bone interface. No study on into-tunnel RCR has been conducted.

Hypothesis

Into-tunnel RCR could promote fibrocartilage regeneration at the tendon-bone interface and has biomechanical advantage over onto-surface repair in a rabbit rotator cuff tear model.
Study Design: Controlled laboratory study.

Methods

Thirty-six New Zealand White rabbits were used in this study. The supraspinatus tendons were cut from the footprint to create a rotator cuff tear on both shoulders. On one side, the supraspinatus was cut longitudinally into 2 halves, sutured, and pulled into 2 tunnels through the greater tuberosity (into-tunnel repair). On the other side, the tendon was reattached to the sur- face of the footprint with transosseous sutures (onto-surface repair). Twelve animals were sacrificed, of which 6 were used for a histological examination and the other 6 for biomechanical testing, at 4, 8, and 12 weeks, respectively.

Results

The tendon-bone interface in the into-tunnel group showed a different healing pattern from that in the onto-surface group. In the former, most of the tendon tissue in the tunnel was replaced with newly generated fibrocartilage; the rest of the tendon fibers appeared in large bundles with direct connection to the bone. In the latter, fibrocartilage regeneration was seldom found at the tendon-bone interface; the tendon near the bone surface appeared as small fibrils. The biomechanical evaluation revealed a higher ultimate load (P <.001) and stiffness (P < .001) at the tendon-bone junction in the into-tunnel group than those in the onto-surface group at 12 weeks.

Conclusion

In a rabbit rotator cuff tear model, into-tunnel RCR could result in a different tendon-bone healing pattern, with obvi- ous fibrocartilage regeneration at the interface and higher tendon-bone healing strength than that in onto-surface repair.
Clinical Relevance: New RCR patterns may be developed to improve the tendon-bone healing pattern and obtain better tendon- bone healing strength.