Augmentation with a reinforced acellular fascia lata strip graft limits cyclic gapping of supraspinatus repairs in a human cadaveric model.

Background: A reinforced biologic strip graft was designed to mechanically augment the repair of rotator cuff tears that are fully reparable by arthroscopic techniques yet have a likelihood of failure. This study assessed the extent to which augmentation of human supraspinatus repairs with a reinforced fascia strip can reduce gap formation during in vitro cyclic loading.

Methods: The supraspinatus tendon was sharply released from the proximal humerus and repaired back to its insertion with anchors in 9 matched pairs of human cadaveric shoulders.

Bone Graft Substitute Provides Metaphyseal Fixation for a Stemless Humeral Implant.

Stemless humeral fixation has become an alternative to traditional total shoulder arthroplasty, but metaphyseal fixation may be compromised by the quality of the trabecular bone that diminishes with age and disease, and augmentation of the fixation may be desirable. The authors hypothesized that a bone graft substitute (BGS) could achieve initial fixation comparable to polymethylmethacrylate (PMMA) bone cement. Fifteen fresh-frozen human male humerii were randomly implanted using a stemless humeral prosthesis, and metaphyseal fixation was augmented with either high-viscosity PMMA bone cement (PMMA group) or a magnesium-based injectable BGS (OsteoCrete; Bone Solutions Inc, Dallas, Texas) (OC group).

Reinforced fascia patch limits cyclic gapping of rotator cuff repairs in a human cadaveric model.

Background: Scaffolds continue to be developed and used for rotator cuff repair augmentation, but clinical or biomechanical data to inform their use are limited. We have developed a reinforced fascia lata patch with mechanical properties to meet the needs of musculoskeletal applications. The objective of this study was to assess the extent to which augmentation of a primary human rotator cuff repair with the reinforced fascia patch can reduce gap formation during in vitro cyclic loading.

Effect of pretension and suture needle type on mechanical properties of acellular human dermis patches for rotator cuff repair.

Background: Dermal grafts are used for rotator cuff repair and augmentation. Although the in vitro biomechanical properties of dermal grafts have been reported previously, clinical questions related to their biomechanical performance as a surgical construct and the effect of surgical variables that could potentially improve repair outcomes have not been studied.

Methods: This study evaluated the failure and fatigue biomechanics of acellular dermis constructs tested in a clinically relevant size (4 × 4 cm patches) and manner (loaded via sutures) for rotator cuff repair.

Improved time-zero biomechanical properties using poly-L-lactic acid graft augmentation in a cadaveric rotator cuff repair model.

Hypothesis: Rotator cuff repair failure rates range from 20% to 90%, and failure is believed to occur most commonly by sutures cutting through the tendon due to excessive tension at the repair site. This study was designed to determine whether application of a woven poly-L-lactic acid device (X-Repair; Synthasome, San Diego, CA) would improve the mechanical properties of rotator cuff repair in vitro.

Materials And Methods: Eight pairs of human cadaveric shoulders were used to test augmented and non-augmented rotator cuff repairs.

Rotator cuff repair augmentation in a canine model with use of a woven poly-L-lactide device.

Background: Despite advances in surgical treatment options, failure rates of rotator cuff repair have continued to range from 20% to 90%. Hence, there is a need for new repair strategies that provide effective mechanical reinforcement of rotator cuff repair as well as stimulate and enhance the intrinsic healing potential of the patient. The purpose of this study was to evaluate the extent to which augmentation of acute repair of rotator cuff tendons with a newly designed poly-L-lactide repair device would improve functional and biomechanical outcomes in a canine model.

Biomechanical characteristics of hybrid hook-screw constructs in short-segment thoracic fixation.

Study Design: Ex vivo biomechanical testing of human cadaveric thoracic spine segments.

Objective: To determine whether a hybrid construct, using a combination of pedicle screws (PSs) and lamina hooks, was equivalent to a PS construct, in a short-segment thoracic spine fixation model.

Summary Of Background Data: Comparisons have been made among PS, lamina hook, and hybrid screw-hook constructs, but these have generally been in long-segment scoliosis correction.

A preliminary biomechanical evaluation in a simulated spinal fusion model. Laboratory investigation.

Object: A preliminary in vitro biomechanical study was conducted to determine if the pressure at a bone graft-mortise interface and the load transmitted along a ventral cervical plate could be used as parameters to assess fusion status.

Methods: An interbody bone graft and a ventral plate were placed at the C3-4 motion segment in six fresh cadaveric goat spines. Polymethylmethacrylate (PMMA) was used to simulate early bone fusion at the bone graft site.

Primary pedicle screw augmentation in osteoporotic lumbar vertebrae: biomechanical analysis of pedicle fixation strength.

Study Design: Pedicle screw pullout testing in osteoporotic and control human cadaveric vertebrae, comparing augmented and control vertebrae.

Objective: To compare the pullout strengths of pedicle screws fixed in osteoporotic vertebrae using polymethyl methacrylate delivered by 2 augmentation techniques, a standard transpedicular approach and kyphoplasty type approach.

Summary Of Background Data: Pedicle screw instrumentation of the osteoporotic spine carries an increased risk of screw loosening, pullout, and fixation failure.

Atlantoaxial fusion: a biomechanical analysis of two C1-C2 fusion techniques.

Background Context: Different atlantoaxial fusion techniques are used for instability. Transarticular screws are biomechanically superior to wiring techniques and equivalent to C1 lateral mass to C2 pedicle (C1LM-C2P) fixation. Recently, C1 lateral mass to C2 laminar (C1LM-C2L) fixation has been shown to have flexibility similar to C1LM-C2P fixation in flexion, extension, lateral bending, and axial rotation.

Biomechanical comparison of adjacent segmental motion after ventral cervical fixation with varying angles of lordosis.

Background Context: Complications, such as graft subsidence and adjacent segment degeneration, are not uncommon after ventral cervical fusion. It has been theorized, but not proven, that sagittal alignment may affect this process. It is therefore hypothesized that increasing lordosis during anterior cervical fusion decreases adjacent segment motion (ASM) and thus decreases the rate of adjacent disc degeneration.

Adjacent level load transfer following vertebral augmentation in the cadaveric spine.

Study Design: In vitro biomechanics.

Objective: To determine if osteoporotic vertebral compression fracture (VCF) augmentation increases adjacent level load transfer.

Summary Of Background Data: Osteoporotic VCF subsequent to augmentation may result from disease progression or increased adjacent level load transfer, or both.

The mechanics of polymethylmethacrylate augmentation.

Osteoporosis frequently leads to vertebral compression fractures. Percutaneous cement augmentation, one recent technique, may alter the biomechanics of the vertebral body and spinal segment. These alterations reportedly predispose the spinal segment to additional vertebral compression fractures.

Thoracic transfacet pedicle screw fixation: a new instrumentation technique.

Object: Pedicle screw instrumentation of the thoracic spine remains technically challenging. Transverse process and costotransverse screw fixation techniques have been described as alternatives to pedicle screw fixation (PSF). In this study, the authors introduce thoracic transfacet PSF and compare its experimental biomechanical results with those of standard PSF in short-term cyclic loading in cadaveric thoracic specimens.

The effects of the antiresorptive agents calcitonin and pamidronate on spine fusion in a rabbit model.

Background Context: As the population ages, the number of individuals undergoing pharmacotherapy to prevent or treat osteoporosis is increasing. Drugs of the bisphosphonate family prevent bone resorption, as does calcitonin, though by different mechanisms. Bisphosphonates are deposited in bone, preventing resorption by osteoclasts.