The purpose of this study was to determine and compare the effects of radiofrequency ablation and mechanical shaving on tendon using histological and ultrastructural techniques. A single cut using a scalpel blade was used to create a standardised reproducible lesion in 12 freshly harvested ovine infraspinatus tendons. Each lesion was then subjected to either bipolar radiofrequency ablation or mechanical shaving. Specimens were either fixed in formalin and processed for light microscopy or fixed in glutaraldehyde and processed for transmission electron microscopy. Samples of normal and untreated cut tendon were analysed as suitable controls. The radiofrequency treated samples showed an area of coagulative necrosis with an average diameter of 2mm around the lesion. Conversely, the shaved samples showed viable cells up to the edges of the lesion. These findings were supported by ultrastructural appearances, which showed preservation of tendon architecture in shaved samples and widespread denaturation of the tendon matrix with loss of fibrillar structure in the radiofrequency treated samples. Radio-frequency electrical energy and mechanical shaving are often used for resection of soft tissues during arthroscopic reconstructive procedures. The effects of these techniques on tendon are not yet clearly understood. The results of this study indicate that thermal resection of tendon causes an immediate additional 2mm area of tissue necrosis which is not present after mechanical shaving. These findings may have implications for the success of arthroscopic debridement and tendon repair procedures.

Aims: Surgical joint stabilisation can be achieved by capsular plication or thermal shrinkage. We hypothesised that there was no difference in mechanical and morphological properties after reduction of laxity in ligaments treated by either technique.

Methods: 30 skeletally mature female rabbits underwent either ‘thermal’ treatment, or ‘plication’ of their left medial collateral ligament (MCL). After 12 weeks convalescence, MCL complexes were procured from left and contralateral knees to undergo viscoelastic (creep) testing, quantitative transmission electron microscopy (TEM) and immunohistochemistry.

Results: Mean creep strain in both thermal (1.85 +/− 0.32%) and plicated ligaments (1.92 +/− 0.36%) was almost twice that of the control group (1.04 +/− 0.15%), although there was no difference between treatment modalities. 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 heterogeneous fibrils (Fig. I). Immunohistochemistry followed by TEM revealed a random distribution of alpha-smooth muscle actin staining fibroblasts in both thermal and plicated groups.

Conclusion: Susceptibility to creep, and residual deformation after recovery, is similar after thermal shrinkage or plication, although inferior to intact ligaments. However, a different pattern of remodelling was revealed in the treatment groups. The plicated results suggest remodelling 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 play an insignificant role in regulation of matrix tension during healing.

Purpose: The glenoid labrum is a significant passive stabiliser of the shoulder joint. However, its microstructural form remains largely unappreciated, particularly in the context of function. An understanding of the labral structure leads to mechanical hypotheses, and therefore functional role in stability and load distribution, will aid an educated approach to surgical timing and repair.

Method: Fresh frozen cadaveric shoulders were grossly harvested via an extended Deltopectoral incision. The Glenohumeral joint was arthroscoped using a modification of Snyders (1989) routine in order to determine the specific anatomy of the capsulolabral complex. The glenoid fossa was then osteotomised before using micro-surgical loupes to section the labrum. Specimens were analysed using Scanning and Transmission Electron Microscopy and Confocal microscopy. Standard processing procedures were used to examine TEM specimens and the data was quantified by computational analysis. Specimens for SEM were cryofractured and Extracellular Matrix removed using a cell maceration technique to expose collagen fibre networks. Images were evaluated qualitatively. Sliced specimens for confocal were serially analysed along their z-axis, and post-processed to form 3-D reconstructions of collagen fibres.

Results: Two distinct homogenous areas were identified: (1) a superficial tight meshwork of fibrils and (2) a deep layer with a densely packed fibrous braid which were circumferential in orientation. A third area showed varying distribution of loosely arranged collagen fibres ranging from small fibres apposing area 1 to larger interleaved groupings near area 2. In radial transverse section, both normal and abnormal (stellate and spiral) fibrils were identified.

Conclusion: Contrary to published evidence, our results suggest the glenoid labrum is subjected a number of mechanical environments. Possibly distinct regions of the labrum contribute to load sharing; a well vascularised hydrated compressive zone and a tensile component distributing circumferential hoop stress, whilst both braiding and region interfaces suggest shear conditions.

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.