Abstract
Surgical joint stabilisation can be achieved by ligamentous plication or thermal shrinkage, and as such, we hypothesized that there is no difference in mechanical and morphological properties after reduction of laxity in ligaments treated by either technique.
Methods: 30 mature female rabbits underwent either ‘thermal’ treatment of their left medial collateral ligament (MCL) using a bipolar radiofrequency probe, or plication with two 4/O non-absorbable sutures following division along its midsubstance and loaded positioning of the free ends. After 12 weeks convalescence, the animals were euthanised and MCL complexes were procured from left and contralateral knees to undergo viscoelastic (creep) testing, quantitative Transmission Electron Microscopy (TEM) and immunohistochemistry. The TEM data was quantified by two data procurement protocols; computational analysis and manual graticule.
Mean creep strain in both thermal (1.85 +/− 0.32%) and plicated ligaments (1.92+/−0.36%) was almost twice that of the control (1.04+/−0.15%), although there was no difference between treatment modalities. Similar findings were seen in the thermal (1.77+/−0.45%), plication (1.85+/−0.40%) and control groups (0.92+/−0.20%) for viscoplastic deformation. However, collagen morphological parameters of all three groups were significantly different (p< 0.001). The thermal ligaments demonstrated predominantly small fibrils, whilst the plicated group displayed an intermediate distribution of heterogenous fibrils. Immunohistochemistry followed by TEM revealed a sparse random distribution of alpha-smooth muscle actin staining fibroblasyts in both thermal and plicated groups. There was an insignificant difference in computational and manual procurement methods (p=0.84).
Susceptibility to creep, and residual deformation after recovery, is similar after thermal shrinkage or plication, although inferior to intact ligaments. However, the plicated results suggest remodeling on a pre-existing fibrillar scaffold, yet the thermal group demonstrated histomorphometry similar to scar tissue, suggesting de novo synthesis. The absence of contractile myofibroblasts suggests that these cells may have an insignificant role in regulation of matrix tension during healing.
These abstracts were prepared by Mr Cormac Kelly. Correspondence should be addressed to him c/o British Orthopaedic Association, Royal College of Surgeons, 35-43 Lincoln’s Inn Fields, London WC2A 3PN.
