Guidelines for cortical screw versus pedicle screw selection from a fatigued decompressive lumbar laminectomy model show similar stability and less bone mineral density dependency.

Background: Traditional pedicle screws are the gold standard for lumbar spine fixation; however, cortical screws along the midline cortical bone trajectory may be advantageous when lumbar decompression is required. While biomechanic investigation of both techniques exists, cortical screw performance in a multi-level lumbar laminectomy and fusion model is unknown. Furthermore, longer-term viability of cortical screws following cyclic fatigue has not been investigated.

Biomechanical evaluation of traditional posterior versus anterior spondylolisthesis reduction in a cadaveric grade I slip model.

Objective: Posterior reduction with pedicle screws is often used for stabilization of unstable spondylolisthesis to directly reduce misalignment or protect against micromotion while fusion of the affected level occurs. Optimal treatment of spondylolisthesis combines consistent reduction with a reduced risk of construct failure. The authors compared the reduction achieved with a novel anterior integrated spacer with a built-in reduction mechanism (ISR) to the reduction achieved with pedicle screws alone, or in combination with an anterior lumbar interbody fusion (ALIF) spacer, in a cadaveric grade I spondylolisthesis model.

Stabilization of the craniocervical junction after an internal dislocation injury: an in vitro study.

Background Context: Reconstructive surgeries at the occipitocervical (OC) junction have been studied in treating degenerative conditions. There is a paucity of data for optimal fixation for a traumatically unstable OC joint. In clinical OC dislocations, segmental fixation may be impossible because of vertebral artery injury or fracture.

Additional sagittal correction can be obtained when using an expandable titanium interbody device in lumbar Smith-Peterson osteotomies: a biomechanical study.

Background Context: Insertion of intervertebral fusion devices between consecutive Smith-Peterson osteotomies (SPOs) provides an anterior fulcrum during compression, which has been documented to improve achievable Cobb angle correction. Extension of these principles to an expandable device would theoretically provide greater surgical adjustment for flatback and scoliotic cases than a static cage.

Purpose: To investigate whether an expandable titanium interbody device would produce greater sagittal correction than a static spacer when used during SPO procedures.

A risk calculator for short-term morbidity and mortality after hip fracture surgery.

Objective: Hip fractures are a common source of morbidity and mortality among the elderly. Although multiple prior studies have identified risk factors for poor outcomes, few studies have presented a validated risk stratification calculator.

Methods: The American College of Surgeons National Surgical Quality Improvement Program database was used to identify 4331 patients undergoing surgery for hip fracture between 2005 and 2010.

Femoral remodeling around Charnley total hip arthroplasty is unpredictable.

Background: There are two unusual remodeling patterns of the proximal femur around well-fixed Charnley total hip arthroplasties: cortical thinning leading to endosteal widening around the femoral component and hypertrophy of the distal femoral cortex. Previous studies have shown remodeling patterns are affected by stem design and occur early postoperatively. It is unclear if these changes are related to patient demographics or if they progress throughout the lifetime of the implant.

Imaging biopsy composition at ACL reconstruction.

Purpose: Early-stage osteoarthritis (OA) includes glycosaminoglycan (GAG) loss and collagen disruption that cannot be seen on morphological magnetic resonance imaging (MRI). T1ρ MRI is a measurement that probes the low-frequency rate of exchange between protons of free water and those from water associated with macromolecules in the cartilage's extracellular matrix. While it has been hypothesized that increased water mobility resulting from early osteoarthritic changes cause elevated T1ρ MRI values, there remain several unknown mechanisms influencing T1ρ measurements in cartilage.

Comparison of T1ρ, dGEMRIC, and quantitative T2 MRI in preoperative ACL rupture patients.

Rationale And Objectives: T1ρ, inversion recovery sequence with a gadolinium contrast agent (dGEMRIC), and T2 mapping have shown sensitivity toward different osteoarthritic-associated compositional changes after joint injury, but have not been studied concomitantly in vivo. We hypothesized that these magnetic resonance imaging sequences can be used to measure early glycosaminoglycan (GAG) losses and collagen disruption in cartilage of anterior cruciate ligament (ACL) rupture patients.

Materials And Methods: Thirteen acute ACL rupture patients were each imaged during a 4-hour presurgery workup to acquire a fast-spin-echo-based T1ρ sequence, a multi-echo spin-echo T2 sequence, and T1-weighted dGEMRIC an average of 55.

Volar/dorsal compressive mechanical behavior of the transverse carpal ligament.

Mechanical insult to the median nerve caused by contact with the digital flexor tendons and/or carpal tunnel boundaries may contribute to the development of carpal tunnel syndrome. Since the transverse carpal ligament (TCL) comprises the volar boundary of the carpal tunnel, its mechanics in part govern the potential insult to the median nerve. Using unconfined compression testing in combination with a finite element-based optimization process, nominal stiffness measurements and first-order Ogden hyperelastic material coefficients (μ and α ) were determined to describe the volar/dorsal compressive behavior of the TCL.

Integrating carthage-specific T1rho MRI into knee clinic diagnostic imaging.

With a rise in post-traumatic osteoarthritis, OA no longer is considered just a disease of aging. The 'gold standard' for OA diagnosis has long been planar radiographs for visualizing osteophytes, joint space narrowing and sclerotic changes. A typical magnetic resonance imaging (MRI) protocol will acquire proton density, T1, T2, and fat suppressed images that give a comprehensive picture of morphologic changes associated with injury and subsequent degenerative processes.