Experimental Study of Umbilical Cord Graft and Established Sling Materials for Frontalis Suspension

Frontalis suspension surgery is the preferred treatment option for patients with poor levator function ptosis. This procedure connects the affected eyelid to the brow using sling material, harnessing the action of the frontalis muscle to elevate the upper eyelid. Various sling materials have been used, most commonly silicone rods and fascia lata. However, both have notable limitations: silicone rods carry a relatively high risk of postoperative inflammation and ptosis recurrence, while fascia lata, due to its low elasticity, may cause blinking dysfunction and exposure keratopathy. Additionally, fascia lata harvesting poses challenges in young children. Therefore, there is a need for an alternative human tissue sling material that is both readily available and capable of overcoming the limitations of established sling materials. This study aimed to evaluate the viability of human umbilical cord grafts as a novel sling material for frontalis suspension surgery in ptosis patients. We developed a new method for dissecting and dehydrating umbilical cord tissue and assessed its mechanical and histological properties using uniaxial tensile testing and histological analysis. Untreated umbilical cord grafts exhibited mechanical strength (15.9546 ± 2.6117 N) and strain (96.8674 ± 3.6707%) values intermediate between those of silicone rod and fascia lata. Alcohol dehydration significantly increased ultimate tensile strength and maximum strain, ultimate strength values exceeding those of silicone rod. These grafts withstood forces exceeding those generated during forced blinking, outperforming silicone rod in strength and exhibiting greater elasticity than fascia lata. Histological analysis revealed abundant collagen and glycosaminoglycans within Wharton's jelly, alongside elastic fiber-rich regions in vessel walls. The presence of these extracellular matrix components likely underlies the grafts' favorable mechanical properties. Overall, umbilical cord grafts may emerge as a promising alternative to conventional sling materials in ptosis surgery, potentially addressing limitations in material availability.