Calcium Phosphate Bone Void Filler Increases Threaded Suture Anchor Pullout Strength: A Biomechanical Study.

Area of Science:

• Orthopedic biomechanics
• Biomaterials science
• Surgical implant technology

Background:

• Suture anchor pull-out from osteoporotic bone is a significant clinical concern.
• Investigating methods to enhance the fixation strength of orthopedic implants is crucial for improving patient outcomes.
• Calcium phosphate bone substitute materials offer potential for bone void filling and augmentation.

Purpose of the Study:

• To compare the cyclic loading response and ultimate pull-out strength of threaded suture anchors.
• To evaluate the efficacy of calcium phosphate bone substitute material (CP-BSM) augmentation.
• To assess augmentation in both a polyurethane foam block model mimicking osteoporotic bone and an in vitro cadaveric humerus model.

Main Methods:

• A controlled biomechanical study involving two models: polyurethane foam blocks and proximal humerus cadaveric specimens.
• Foam blocks and cadaveric bone were either augmented with injectable CP-BSM or left untreated.
• Specimens were instrumented with threaded suture anchors and subjected to cyclic axial loading (40 cycles) followed by load-to-failure testing.

Main Results:

• Augmentation with CP-BSM significantly increased average pull-out strength in the osteoporotic foam block model (332.68 N vs. 144.38 N, P = .005).
• Similarly, CP-BSM augmentation significantly enhanced average pull-out strength in the cadaveric humerus model (274.07 N vs. 138.53 N, P = .029).
• Failure modes were analyzed, with augmentation demonstrating improved load-to-failure resistance.

Conclusions:

• Augmentation of osteoporotic bone models with calcium phosphate bone substitute material significantly increases the pull-out strength of threaded suture anchors.
• CP-BSM augmentation provides enhanced load-to-failure resistance, addressing clinical concerns regarding suture anchor fixation in osteoporotic bone.