Background: The menisci are integral to normal knee function. purpose of this study was measure the contact pressures transmitted medial tibial plateau under physiological loads as a function percentage meniscus involved by radial tear or repair. Our hypotheses were that (1) there is threshold size tears above which mechanics adversely affected, and (2) partial meniscectomy results in increased pressure compared with found after meniscal Methods: A simulator used apply multidirectional...

ABSTRACT Reduced bioavailability of estrogen increases skeletal fracture risk in postmenopausal women, but the mechanisms by which regulates bone mass are incompletely understood. Because signaling acts, part, through receptor alpha (ERα), mice with global deletion ERα (ERαKO) have been used to determine role biology. These animals, however, confounding systemic effects arising from other organs, such as increased and decreased insulin-like growth factor 1 (IGF-1) serum levels, may...

ABSTRACT Sclerostin, encoded by the Sost gene, is an important negative regulator of bone formation that has been proposed to have a key role in regulating response mechanical loading. To investigate effect long-term Sclerostin deficiency on mechanotransduction bone, we performed experiments unloaded or loaded tibiae 10 week old female Sost−/− and wild type mice. Unloading was induced via 0.5U botulinum toxin (BTX) injections into right quadriceps calf muscles, causing muscle paralysis limb...

Estrogen receptor alpha (ERα) has been implicated in bone's response to mechanical loading both males and females. ERα osteoblast lineage cells is important for determining bone mass, but results depend on animal sex the cellular stage at which deleted. We demonstrated previously that when deleted from mature osteoblasts osteocytes mixed-background female mice, mass strength are decreased. However, few studies exist examining skeletal cell-specific ERαKO mice. Therefore, we crossed floxed...

The tibial post in posterior-stabilized total knees is a potential source of polyethylene wear debris, but the relationship between shape and location relation to tibiofemoral bearing surfaces subsequent damage patterns remains unknown.We used observations made on retrieved implant components from three contemporary knee designs examine how differences design affected post.We examined 113 Zimmer NexGen(®), 103 Exactech Optetrak(®), 58 Smith Nephew Genesis(®) II inserts using subjective scale...

Mobile-bearing TKAs reportedly have no clinical superiority over fixed-bearing TKAs, but a potential benefit is improved polyethylene wear behavior.We asked whether extent of damage and patterns would be less severe on retrieved mobile-bearing than if correlations with patient demographics could explain differences in or locations damage.We performed grading mapping 48 due to osteolysis/loosening, infection, stiffness, instability malpositioning. Visual used stereomicroscopy identify damage,...

Highly crosslinked UHMWPE is associated with increased wear resistance in hip simulator and clinical studies. Laboratory case studies, however, have described rim fracture acetabular liners. Controversy exists, therefore, on the relative merits of liners over conventional terms performance versus to fatigue cracking.We asked whether would show less surface damage than but be more susceptible damage.We examined 36 39 retrieved implants similar patient demographics identical design for...

The effects of tears the anterior cruciate ligament on knee kinematics and contact mechanics during dynamic everyday activities, such as gait, remains unclear. objective this study was to characterize ligament–deficient simulated gait. Nine human cadaveric knees were each augmented with a sensor capable measuring normal stresses tibial plateau, mounted load-controlled simulator, subjected physiological, multidirectional, loads mimic Using mixed model random identifiers, confidence intervals...

Introduction of highly crosslinked polyethylene has increased interest in large femoral heads, because thin acetabular liners can be used while maintaining low wear rates and larger heads decrease the incidence instability. However, crosslinking subsequent thermal treatments cause decreased mechanical properties that might obviate reduced under extreme conditions. To examine whether contact pressures would adversely affect liners, we tested thick (3.8 mm thickness/44-mm head 7.9...

Biophysical stimuli may be an effective therapy to counteract age-related changes in bone structure that affect the primary stability of implants used joint replacement or fracture fixation. The influence controlled mechanical loading on osseointegration was investigated using vivo device implanted distal lateral femur 12 male rabbits. Compressive loads (1 MPa, 1 Hz, 50 cycles/day, 4 weeks) were applied a porous titanium foam implant and underlying cancellous bone. contralateral limbs served...

Abstract Endothelial cells line all major blood vessels and serve as integral regulators of many functions including vessel diameter, cellular trafficking, transport soluble mediators. Despite similar functions, the phenotype endothelial is highly organ-specific, yet our understanding mechanisms leading to organ-level differentiation incomplete. We generated 3D microvessel networks by combining a common naïve cell with six different stromal derived from lung, skin, heart, bone marrow,...

Abstract A novel porous titanium foam implant has recently been developed to enhance biological fixation of orthopaedic implants bone. The aim this study was examine the mechanical and histological characteristics bone apposition into two different pore sizes (565 464 micron mean void intercept length) compare these those obtained with a fully conventionally sintered bead implant. Cylindrical were studied in rabbit distal femoral intramedullary osseointegration model at time zero 3, 6, 12...

Minimally invasive techniques and biological autograft alternatives such as the bone morphogenetic proteins (BMPs) can reduce morbidity associated with spinal fusions. This study was a proof-of-concept for gene-therapy-mediated anterior spine fusion that could be adapted to percutaneous technique clinical use. Isogeneic marrow stromal cells genetically programmed express b-galactosidase (LACZ, marker gene), BMP2, BMP7, mixture of BMP2 BMP7 infected (homodimers, HM), or BMP2/7 heterodimers...