Tendon augmentation grafts: biomechanical failure loads and failure patterns.

Area of Science:

• Biomaterials science
• Orthopedic surgery
• Tissue engineering

Background:

• Tendon augmentation and substitution grafts are crucial in orthopedic repairs.
• Understanding the mechanical properties of available xenografts and allografts is essential for clinical success.
• Graft failure can occur due to inadequate suture retention or material weakness.

Purpose of the Study:

• To determine the load to failure strengths of various commercially available tendon augmentation xenografts and allografts.
• To identify the modes of failure for these graft materials under tensile load.
• To compare the mechanical properties of different graft types, including human skin, porcine skin, bovine skin, and porcine small intestine submucosa.

Main Methods:

• An experimental laboratory study was conducted using a standardized testing methodology.
• Commercially available grafts (GraftJacket, CuffPatch, Restore, Permacol, TissueMend) were hydrated and prepared with a mattress stitch.
• Tensile loads to failure were applied using an Instron machine to evaluate suture graft construct strength and failure modes.

Main Results:

• GraftJacket (human skin) exhibited the highest load to failure (up to 229 N), followed by Permacol (porcine skin) and TissueMend (bovine skin).
• Restore and CuffPatch (porcine small intestine submucosa) demonstrated significantly lower loads to failure (38 N and 32 N, respectively).
• Failure predominantly occurred via suture pull-through, with specific patterns like isthmus pullout or end pullout varying by implant type.

Conclusions:

• The testing methodology reliably assesses suture retention strength in tendon grafts.
• Skin-derived grafts possess superior load-to-failure characteristics compared to intestine submucosa grafts.
• Recognizing distinct failure modes for each graft type is critical for optimizing surgical fixation and patient rehabilitation.