STUDY DESIGN Measurement of the kinematics of the lumbar spine after insertion of an interspinous spacer in vitro. OBJECTIVES To understand the kinematics of the instrumented and adjacent levels due to the insertion of this interspinous implant. SUMMARY OF BACKGROUND DATA An interspinous spacer (X Stop, SFMT, Concord, California) has been developed to treat neurogenic intermittent claudicat...

INTRODUCTION: Conventional wisdom dictates that fusion rates increase with increasing construct stiffness. Traditional pedicle screw systems generally rely upon stiff components and rigid interconnections. For ease of insertion, some "semi-rigid" systems include polyaxial connections. A favorable bio logical outcome (fusion) is only weakly related to instrumentation type and it is increasingly ...

Increased conformity at the tibiofemoral articulation increases contact area and reduces contact stresses in total knee arthroplasty. Malalignment, however, can increase polyethylene contact stresses. The effect of knee alignment and articular conformity on contact stresses was evaluated in a finite element model. The polyethylene insert and femoral component were modeled in high- and low-confo...

OBJECTIVE The objective of this biomechanical study was to evaluate the stability provided by a newly developed shape memory alloy hook (SMAH) in a cadaveric transforaminal lumbar interbody fusion (TLIF) model. METHODS Six human cadaveric spines (L1-S2) were tested in an in vitro flexibility experiment by applying pure moments of ±8 Nm in flexion/extension, left/right lateral bending, and lef...

Methods In this case control study, 11 patients with long thoracic curves (imbalanced three-curve pattern or A1 from the Rigo classification) were treated with a specifically designed RSC brace called "three curves brace with open pelvis." These 11 patients were compared to a control group of 10 patients with the same age and curve magnitude, treated with a classical RSC brace for a three-curve...

PURPOSE The aim of this study was to investigate the biomechanical stability provided by a novel, polylactic acid/nano-sized, β-tricalcium phosphate, bioabsorbable, self-retaining cervical fusion cage (BCFC). METHODS Quasistatic nonconstraining torques (maximum 1.5 NM) induced flexion, extension, lateral bending (±1.5 NM), and axial rotation (±1.5 NM) on 32 sheep cervical spines (C2-C5). The ...

Osteoarthritis of the carpometacarpal joint of the thumb (CMCJ) is a frequent clinical problem. The aim of the study was to discuss the mechanisms of circumduction and axial rotation of the CMCJ considering geometrical properties of the articulating surfaces and the configuration of the muscle system acting over the CMCJ. 28 CMCJ from 7 female and 7 male corpses (age: 81 yrs (median), 53-91 yrs...

OBJECTIVE The spinopelvic kinematics of sweep and scull have yet to be investigated, despite evidence suggesting that sweep rowing may be provocative for low back pain (LBP). The aim of this study was to determine whether differences existed in spinopelvic kinematics in high-level rowers without LBP in sweep and scull ergometer rowing. DESIGN Repeated measures study. SETTING Institute of Sp...

Minimally invasive (MI) lumbar decompression became a common approach to treat lumbar stenosis. This approach may potentially mitigate postoperative increases in segmental motion. The goal of this study was to evaluate modifications to segmental motion in the lumbar spine following a MI unilateral approach as compared to traditional facet-sparing and non-facet sparing decompressions. Six human ...

OBJECTIVE To define the kinematic motion patterns of the canine cervical spine, with a particular emphasis on identifying differences between the cranial (C(2)-C(4)) and caudal (C(5)-C(7)) segments, and to determine the significance of coupled motions (CM) in the canine cervical spine. STUDY DESIGN Cadaveric biomechanical study. SAMPLE POPULATION Cervical spines of 8 Foxhounds. METHODS Sp...