Effects of posterior distraction forces on anterior column intradiscal pressure in the dual growing rod technique.

Background: Little evidence is available addressing biomechanical properties of posterior distraction forces and their effects on anterior spinal column in the growing rod technique. The question is often asked if posterior distraction forces may be kyphogenic. The goal of this study is to determine whether posterior distraction forces transmitted anteriorly through different foundation constructs (i.

A titanium expandable pedicle screw improves initial pullout strength as compared with standard pedicle screws.

Background Context: Pedicle screws are now standard for spinal arthrodesis as they provide three-column spinal stabilization. Decreased vertebral body bone density because of aging reduces the stability of the bone-screw interface, potentially increasing screw pullout or pseudarthrosis. Modifications to standard pedicle screw designs to improve screw stabilization may help to compensate for the detrimental effects of decreased vertebral bone density.

Biomechanical comparison of locking versus nonlocking volar and dorsal T-plates for fixation of dorsally comminuted distal radius fractures.

Objectives: The purpose of this study was to gain insight into the effect of plate location and screw type for fixation of extra-articular distal radius fractures with dorsal comminution (Orthopaedic Trauma Association Type 23-A3.2).

Methods: Sixteen pairs of cadaver radii were randomized to four plating configurations: dorsal locking, dorsal nonlocking, volar locking, and volar nonlocking.

Biomechanical evaluation of transfacet screw fixation for stabilization of multilevel cervical corpectomies.

Study Design: Cadaveric biomechanical investigation.

Objectives: To test the feasibility of transfacet screws as a minimally invasive posterior fixation device for the cervical spine by comparing the biomechanical stability of transfacet screws to lateral mass screws and rods in a multilevel cervical corpectomy model.

Summary Of Background Data: Minimally invasive surgery (MIS) of the spine has gained increasing acceptance and popularity.

Comparison of mechanical stability in double-row rotator cuff repairs between a knotless transtendon construct versus the addition of medial knots.

Purpose: Our purpose was to investigate the importance of medial-row knot tying to mechanical stability in a double-row rotator cuff repair by comparing a knotless construct with transtendon anchor passage versus a similar construct implementing medial knots.

Methods: A standard defect was created in the infraspinatus tendons of 14 bovine humeri. All defects were repaired with 2 medial and 2 lateral anchors (SutureCross System; KFx Medical, Carlsbad, CA).

An evaluation of fracture stabilization comparing kyphoplasty and titanium mesh repair techniques for vertebral compression fractures: is bone cement necessary?

Study Design: In vitro biomechanical investigation using human cadaveric vertebral bodies.

Objective: To evaluate differences in biomechanical stability of vertebral compression fractures (VCFs) repaired using an expandable titanium mesh implant, with and without cement, as compared with standard balloon kyphoplasty.

Summary Of Background Data: Vertebral augmentation, either in the form of vertebroplasty or kyphoplasty, is the treatment of choice for some VCFs.

Biomechanical comparison of kyphoplasty versus a titanium mesh implant with cement for stabilization of vertebral compression fractures.

Study Design: In vitro biomechanical investigation.

Objective: To evaluate differences in biomechanical stability of vertebral compression fractures repaired using balloon kyphoplasty versus a titanium mesh implant.

Summary Of Background Data: Vertebral compression fractures may be stabilized using an expandable balloon followed by cement injection.

Pedicle screw surface coatings improve fixation in nonfusion spinal constructs.

Study Design: Biomechanical and histologic analysis.

Objective: To compare the strength of the bone-screw interface of standard uncoated pedicle screws with screws treated with hydroxyapatite (HA), titanium plasma spray (TPS), and a composite HA-TPS coating.

Summary Of Background Data: Transpedicular screw fixation has become the gold standard in the treatment of various thoracolumbar spinal conditions.

Reconstruction plates for stabilization of mid-shaft clavicle fractures: differences between nonlocked and locked plates in two different positions.

Reconstruction plates permit contouring to the irregular anatomic shape of the clavicle. This study evaluated the biomechanical stability of locking and nonlocking clavicle reconstruction plates for treating midshaft, transverse fractures, comparing anterior-inferior to superior plate position. Twenty-four synthetic clavicles with mid-shaft fractures were repaired with either a locking or nonlocking clavicle reconstruction plate in either the anterior-inferior or superior plate position (n = 6/group).

Spinal growth modulation with use of a tether in an immature porcine model.

Background: Spinal growth modulation by tethering the anterolateral aspect of the spine, as previously demonstrated in a nonscoliotic calf model, may be a viable fusionless treatment method for idiopathic scoliosis. The purpose of the present study was to evaluate the radiographic, histologic, and biomechanical results after six and twelve months of spinal growth modulation in a porcine model with a growth rate similar to that of adolescent patients.

Methods: Twelve seven-month-old mini-pigs underwent instrumentation with a vertebral staple-screw construct connected by a polyethylene tether over four consecutive thoracic vertebrae.

Biomechanical differences between transfacet and lateral mass screw-rod constructs for multilevel posterior cervical spine stabilization.

Study Design: In vitro biomechanical investigation using human cadaveric cervical spines.

Objective: Evaluate differences in biomechanical stability between typical lateral mass screw + rod constructs compared to transfacet screw fixation with and without rods.

Summary Of Background Data: Lateral mass screw + rod constructs have reported efficacious arthrodesis rates/quality but risk damaging the lateral neurovascular structures.

Biomechanical analysis of supracondylar humerus fracture pinning for slightly malreduced fractures.

Background: The most common position of malreduced type III supracondylar humerus (SCH) fractures is internal rotation and medial collapse of the distal fragment. The purpose of this study was to determine the effect of SCH fracture rotational deformity on stability with various pin configurations. Specifically, is the biomechanical stability lost when an SCH fracture is pinned in slight malreduction (compared with anatomical pinning) improved by adding a third pin?

Methods: Sixty-four synthetic humeri were sectioned in the mid-olecranon fossa to simulate an SCH fracture.

Unilateral and bilateral sacropelvic fixation result in similar construct biomechanics.

Study Design: In vitro biomechanical investigation of lumbosacropelvic spinal instrumentation.

Objective: Determine whether unilateral iliac fixation, with or without an L6 to S1 interbody graft, provides equivalent biomechanical stability compared with bilateral iliac fixation.

Summary Of Background Data: Recent clinical evidence has shown improved clinical outcomes of unilateral iliac fixation compared with bilateral instrumentation that contradicts biomechanical data supporting bilateral instrumentation, although no specific investigation has compared unilateral versus bilateral instrumentation.

Does the direction of pedicle screw rotation affect the biomechanics of direct transverse plane vertebral derotation?

Study Design: In vitro biomechanical investigation using human cadaveric vertebrae.

Objective: Evaluate the biomechanical differences in transverse plane vertebral body derotation maneuvers of thoracic pedicle screws in both medial and lateral directions.

Summary Of Background Data: Thoracic pedicle screws are thought to have better vertebral rotation control and better segmental scoliosis correction compared to hooks and wires.

Residual motion on flexion-extension radiographs after simulated lumbar arthrodesis in human cadavers.

Flexion-extension radiographs are commonly used to assess lumbar fusion. Recommended criteria for solid fusion have varied from 1 to 5 degrees of angular motion between vertebrae. Notwithstanding this wide variation, the validity of these criteria have never been biomechanically tested.

Biomechanical evaluation of clavicle fracture plating techniques: does a locking plate provide improved stability?

Objectives: To evaluate the biomechanical properties of both plate location (superior versus anterior-inferior) and plate type Small Fragment Contourable Dual Compression Plate (CDCP) versus 3.5 mm Universal Locking System Contourable Dual Compression Plate (Locked CDCP) in a synthetic midshaft transverse clavicle fracture model.

Methods: Twenty-four pre-osteomized synthetic clavicles were repaired with either CDCP or locked CDCP technology 3.

Biomechanical comparison of four different fixation techniques for pediatric tibial eminence avulsion fractures.

Background: Several different methods have been used to repair tibial eminence avulsion fractures. It is not clear which is the best stabilization method. The purpose of this study was to compare the biomechanical stability of tibial eminence avulsion fractures using suture, resorbable screw, resorbable nail, and metal screw techniques.

Displaced olecranon fractures in children: a biomechanical analysis of fixation methods.

Background: Wire and suture methods have been used to stabilize pediatric olecranon fractures. This study (1) compared differences in simulated intraoperative compression during fracture reduction, (2) evaluated articular surface compression during cyclic loading of the tension band, and (3) compared fracture stabilization after cyclic physiologic loading at low/high levels.

Methods: Identical olecranon fractures were created in 10 synthetic ulnae and randomized to suture or wire fixation.

Spinal growth modulation with an anterolateral flexible tether in an immature bovine model: disc health and motion preservation.

Study Design: An immature bovine model was used to evaluate multilevel anterolateral flexible tethering in a growing spine.

Objective: To evaluate radiographic, biochemical, histologic, and biomechanical results of tethered spinal growth.

Summary Of Background Data: An anterolateral flexible tether has been shown to create a kyphotic and scoliotic spinal deformity in calves.

Biomechanical evaluation of retrograde intramedullary stabilization for femoral fractures: the effect of fracture level.

Background: Retrograde stabilization of mid-diaphysis adolescent femur fractures has shown excellent biomechanical stability. However, it is unclear whether adequate stability is maintained for distal femur fractures using the retrograde approach compared with the clinically recommended antegrade approach. The purpose of this study was to evaluate the biomechanical stability of retrograde and antegrade nailing for mid-diaphyseal and distal diaphysis femoral fractures.

Biomechanical comparison of fully and partially threaded screws for fixation of slipped capital femoral epiphysis.

Background: Previous data have shown that an equal number of threads on each side of the physis maximizes stability for slipped capital femoral epiphysis (SCFE) fixation. The purpose of the current study was to determine if a fully threaded cancellous screw provides greater stability compared with a partially threaded screw in a porcine model.

Methods: Twenty skeletally immature porcine femurs were sectioned, and a 30-degree angular wedge was resected from the femoral neck to simulate SCFE.

Biomechanical comparison of different anchors (foundations) for the pediatric dual growing rod technique.

Background Context: Children with early onset scoliosis benefit from early operative treatment with dual growing rods as they provide an "internal brace" for the spine and allow curve correction and sequential lengthenings to maximize thoracic cage development. The foundations that provide anchor points for the dual growing rods may incorporate hooks, screws, or a hybrid construct. It is unclear how stable different types of foundation constructs are with regard to pullout.

Single-row suture anchor repair of the rotator cuff is biomechanically equivalent to double-row repair in a bovine model.

Purpose: The purpose of this study was to determine biomechanical differences in cyclic elongation and ultimate strength between double-row rotator cuff repair and single-row repair for partial rotator cuff repairs.

Methods: We randomly assigned 18 immature bovine specimens (aged 12 to 16 weeks) to 3 repair groups (6 per group). A 1 x 2-cm defect was created at the infraspinatus tendon insertion site.

Biomechanical evaluation of an injectable radiopaque polypropylene fumarate cement for kyphoplasty in a cadaveric osteoporotic vertebral compression fracture model.

Vertebral compression fractures cause pain, deformity, and disability. Polypropylene fumarate (PPF) has shown promise as an injectable cement for bone defects but little is known about its performance for kyphoplasty. The purpose of this study was to evaluate the biomechanical performance of PPF for kyphoplasty in simulated anterior compression fractures in cadaveric vertebral bodies.

A biomechanical analysis of a novel arthroscopic suture method compared to standard suture knots and materials for rotator cuff repair.

Purpose: To biomechanically compare a novel suture welding method to 2 standard suture materials when tied with 3 types of arthroscopic knots.

Methods: Sixty suture loops were tied with Weston, Roeder, and Duncan knots for both No. 2 FiberWire (FW) and No.