Ic. Francis et al., Stabilization of the posterior limb of the medial canthal tendon using biodegradable tag anchors: A cadaveric model, OPHTHAL PL, 17(1), 2001, pp. 28-35
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.