Stabilization of the posterior limb of the medial canthal tendon using biodegradable tag anchors: A cadaveric model

Purpose: This study describes and tests in a cadaveric model a new method o f fixation designed for potential stabilization of the posterior limb of th e medial canthal tendon. using biodegradable Tag anchors. Methods: Study of the possibility of performing surgery to repair medial ec tropion using biodegradable polyglyconate Tag anchors was commenced in thp sheep cadaveric head model, and in the whole dry human skull model. This wa s then performed using five preserved human cadaveric whole heads, and pull out tensions were estimated in four of these. Computed tomography and magne tic resonance imaging were obtained for this model in the fifth head, and c omputed 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 he ads. Results: It was possible to obtain good Tag anchor fixation in bone overlyi ng the maxillary and ethmoidal sinuses of the sheep, and in a young human s kull. It was also possible to place adequately the anchor in the medial wal l of the orbit close to the posterior lacrimal crest in all cases in the hu man cadaveric model. Pullout strengths were evaluated and found to range fr om 3.5 N to 12.4 N (mean, 7.5 N). Computed tomography and magnetic resonanc e imaging failed to demonstrate the biodegradable anchors in both the dry; human whole skull and in the fifth cadaveric head, but did demonstrate the bon; defects in the medial orbital walls through which the anchor passed. Conclusions: We have shown, for the first time, the stability of biodegrada ble Tag anchor fixation in a human cadaveric head model using pullout tensi ons and dissection studies. This method would allow adequate strength and s tability to provide for control of fixation of the medial end of the lower eyelid in patients with medial ectropion and medial canthal tendon laxity.