Purpose: This study describes and tests in a cadaveric model a new method of fixation designed for potential stabilization of the posterior limb of the medial canthal tendon, using biodegradable Tag anchors.
Methods: Study of the possibility of performing surgery to repair medial ectropion using biodegradable polyglyconate Tag anchors was commenced in the sheep cadaveric head model, and in the whole dry human skull model. This was then performed using five preserved human cadaveric whole heads, and pullout tensions were estimated in four of these. Computed tomography and magnetic resonance imaging were obtained for this model in the fifth head, and computed tomography was performed on the whole dry human skull. Dissections were carried out to establish the site of the bony defect in each of the heads.
Results: It was possible to obtain good Tag anchor fixation in bone overlying the maxillary and ethmoidal sinuses of the sheep, and in a young human skull. It was also possible to place adequately the anchor in the medial wall of the orbit close to the posterior lacrimal crest in all cases in the human cadaveric model. Pullout strengths were evaluated and found to range from 3.5 N to 12.4 N (mean, 7.5 N). Computed tomography and magnetic resonance imaging failed to demonstrate the biodegradable anchors in both the dry human whole skull and in the fifth cadaveric head, but did demonstrate the bony defects in the medial orbital walls through which the anchor passed.
Conclusions: We have shown, for the first time, the stability of biodegradable Tag anchor fixation in a human cadaveric head model using pullout tensions and dissection studies. This method would allow adequate strength and stability to provide for control of fixation of the medial end of the lower eyelid in patients with medial ectropion and medial canthal tendon laxity.