Article

Effects of selective paralysis of the supraspinatus muscle using botulinum neurotoxin a in rotator cuff healing in rats.

Department of Orthopaedic Surgery, University Hospital of Munich (LMU)-Campus Grosshadern, Marchioninistr. 15, 81377 Munich, Germany. .
Journal of Orthopaedic Research (Impact Factor: 2.88). 12/2012; DOI: 10.1002/jor.22260
Source: PubMed

ABSTRACT We hypothesized that a temporary rotator cuff paralysis using botulinum-neurotoxin A (BoNtA) would lead to an improved tendon-to-bone healing after repair of supraspinatus lesions. One hundred sixty Sprague-Dawley rats were randomly assigned to either the BoNtA or the control (saline) group. BoNtA/saline-solution was injected into the supraspinatus muscle 1 week prior to surgery. A supraspinatus defect was made; we distinguished between a lesion with normal and increased repair load. Furthermore, one subgroup had the operated shoulder immobilized in a cast. Histologic analysis and biomechanical testing followed. Specimens from the BoNtA-group, which were treated with an increased repair load, showed less cellularity and more organization in the interface tissue compared to the saline control group. In addition, we found that the collagen 1-3 quotient in the BoNtA specimen was significantly (p = 0.0051) higher than in the control group. Ultimate load at failure between the groups was not significantly different (p > 0.05). We did not observe any significant differences between the mobilized and immobilized specimen (p = 0.2079). The study shows that tendon-to-bone healing after rotator cuff repair can be altered positively using BoNtA pre-operatively. Tears with increased repair load seem to benefit the most-at least histologically. © 2012 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res.

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    ABSTRACT: Abstract We hypothesized that botulinumneurotoxin A (BoNtA) positively influences tissue characteristics at the re-insertion site when used as an adjuvant prior to rotator cuff repair. One hundred and sixty Sprague-Dawley rats were randomly assigned to either a BoNtA or saline injected control group. BoNtA or saline solution was injected into the supraspinatus muscle one week prior to repair of an artificially created supraspinatus tendon defect. Postoperatively, one subgroup was immobilized using a cast on the operated shoulder while the other had immediate mobilisation. Histologically, the fibrocartilage transition zone was more prominent and better organized in the BoNtA groups when compared to the saline control group. In the immediately mobilized BoNtA groups significantly more collagen 2 at the insertion was detected than in the control groups (p<0.05). Fibre orientation of all BoNtA groups was better organized and more perpendicular to the epiphysis compared to control groups. Tendon stiffness differed significantly (p<0.05) between casted BoNta and casted saline groups. Tendon viscoelasticity was significantly higher (p<0.05) in the immobilized saline groups no matter if repaired with increased or normal repair load. The results of this study suggest that reduction of load at the healing tendon-to-bone interface leads to improved repair tissue properties.
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