Background: Following repairs of large-to-massive tears of the
rotator cuff, the rates of tendon retears are high and often involve tissue
deficiency. Animal studies of the Restore Orthobiologic Implant, a
collagen-based material derived from the small intestine mucosa of pigs, have
indicated that it might be used to help overcome such problems. We carried out
a study to determine whether patients who received this xenograft to augment a
rotator cuff repair exhibited greater shoulder strength, shoulder function,
and/or resistance to retearing.
Methods: We compared data from a group of patients who had undergone
conventional rotator cuff repair with xenograft augmentation (the xenograft
group) with data from a group in whom a repair had been done by the same
surgeon without augmentation (the controls). The groups were matched for
gender, mean age, and mean size of the rotator cuff tear. All subjects
completed a pain and function questionnaire and were given a systematic
clinical shoulder examination preoperatively and at three, six, and
twenty-four months postoperatively. The twenty-four-month visit included
magnetic resonance imaging to determine whether a retear had occurred.
Results: Four patients who had received a xenograft had a severe
postoperative reaction requiring surgical treatment. At two years after the
surgery, six of the ten tendons repaired with a xenograft and seven of the
twelve control tendons had retorn, as documented by magnetic resonance
imaging. The patients with a xenograft had significantly less lift-off
strength, as measured with a dynamometer, and significantly less strength in
internal rotation and adduction than the controls at two years after the
surgery (all p < 0.05). Also, the xenograft group had significantly more
impingement in external rotation, a slower rate of resolution of pain during
activities, more difficulty with hand-behind-the-back activities, and less
sports participation (all p < 0.05).
Conclusions: Two years after surgical repair of a large rotator cuff
defect supplemented with a xenograft, patients had several persisting deficits
and no recognizable benefit as compared with the results in a control group.
In view of these findings, together with the unsatisfactorily high proportion
of patients with a severe inflammatory reaction to the xenograft, we do not
recommend use of the Restore Orthobiologic Implant in its present form.
Level of Evidence: Therapeutic Level III. See
Instructions to Authors for a complete description of levels of evidence.