Stress distribution in the supraspinatus tendon after tendon repair: suture anchors versus transosseous suture fixation.
BACKGROUND
The stress concentration at the site of supraspinatus tendon repair, either by suture anchor fixation or by transosseous suture fixation, has not been fully clarified.


OBJECTIVE
Suture anchor fixation showed higher stress concentrations in the tendon than did transosseous suture fixation.


METHODS
Controlled laboratory study.


METHODS
Three finite element models were developed based on a previously published model of normal supraspinatus tendon (0 degrees abduction). Single-row fixation, double-row fixation, and transosseous suture fixation were simulated. A tensile force was applied to the proximal end of the supraspinatus tendon to simulate its contraction force.


RESULTS
In the single-row model, the stress appeared from the site of the anchor and extended into the proximal tendon. The highest stress concentration was observed on the bursal surface of the tendon. The double-row model showed a similar pattern to the single-row model except that the stress concentration was observed only around the medial anchor. In the transosseous model, the stress appeared from the attachment site to a bony trough, which extended proximally into the tendon substance. No significant stress concentration was observed inside the tendon.


CONCLUSIONS
Both single-row and double-row fixations showed higher stress concentration inside the tendon than did transosseous suture fixation.


CONCLUSIONS
A high stress concentration might be a cause of the rerupture often observed after arthroscopic cuff repair using suture anchors.
Sano
Hirotaka
H
Department of Orthopaedic Surgery, Tohoku University School of Medicine, Sendai, Japan. staka@mail.tains.tohoku.ac.jp
Yamashita
Takeshi
T
Wakabayashi
Ikuko
I
Itoi
Eiji
E
D000222:Adaptation, Physiological; D001696:Biomechanical Phenomena; D006801:Humans; D015233:Models, Statistical; D009119:Muscle Contraction; D018482:Muscle, Skeletal; D016059:Range of Motion, Articular; D017006:Rotator Cuff / Q000601:surgery*; D012785:Shoulder Joint / Q000601:surgery*; D013314:Stress, Mechanical; D053441:Suture Anchors; D013536:Suture Techniques; D013537:Sutures; D013708:Tendon Injuries / Q000209:etiology / Q000601:surgery*; D016896:Treatment Outcome