Abstracts Posters SICOT-SOF meeting Gothenburg 2010 _2_

Poster
Topic: General Orthopaedics
Abstract number: 26470
REDUCED SUBSTANCE P LEVELS IMPEDE TENDON REPAIR
Daniel BRING 1 , Kent PAULSON 2 , Per RENSTRÖM 1 , Paul SALO 3 , Dave HART 3 ,
Paul ACKERMANN 1
1 Section of Orthopaedics and Sports Medicine, Department of Molecular Medicine
and Surgery, Karolinska Institutet, Stockholm (SWEDEN), 2 Design Laboratory,
Schulich School of Engineering, University of Calgary, Calgary (CANADA), 3 McCaig
Institute for Bone and Joint Health and The Division of Orthopaedics, University of
Calgary, Calgary (CANADA)
Tendon repair is characterized by prolonged healing, which is especially marked in
patients with neuropathic conditions. The sensory neuropeptides, substance P (SP)
and calcitonin gene related peptide (CGRP) are involved in nociception as well as in
tissue repair. The impaired healing seen in neuropathic conditions may be a result of
a reduced local presence of sensory neuropeptides. The study was conducted in
order to investigate whether a decreased expression of SP and CGRP during rat
achilles-tendon healing would influence the development of biomechanical tissue
properties. Capsaicin-induced denervation reduced the concentrations of SP by
~60% and CGRP by ~40%, as assessed by radioimmunoassay in the dorsal root
ganglia (DRG). The peripheral neuronal presence of SP and CGRP, as assessed by
immunohistochemistry, was subjectively almost depleted. Looking at intra-individual
correlations, decreased SP levels in the DRG correlated with lower ultimate tensile
strength (UTS) and stress at failure in healing tendons. Furthermore, an individual
decrease in nociception at week 2 was correlated with decreased peripheral
occurrence of SP and was moreover correlated with reduced UTS and stress at
failure at 4 weeks post-tendon injury. Comparing groups at 8 weeks, the denervated
tendon group exhibited higher UTS, failing at tendon midsubstance, than did the
operated controls, which failed at the bone tendinous junction. These findings
suggest that denervation may block a SP-induced remodelling phase at the tendon
bone insertion in the denervated group. In conclusion, a reduced presence of
sensory neuropeptides is associated with impaired development of biomechanical
tissue properties in the healing tendon.
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