Clinical Orthopaedics and Related Research ®

A Publication of The Association of Bone and Joint Surgeons ®

Basic Research 170 articles


Emerging Ideas: Matrix Metalloproteinase-2 in Muscle Atrophy

Xuhui Liu MD

Muscle atrophy impacts almost every patient seen for orthopaedic conditions. Unfortunately, no effective treatment is available to date. Matrix metalloproteinases (MMPs), especially MMP-2, are involved in skeletal muscle atrophy. MMP-2 null mice reportedly have substantially reduced muscle atrophy after tendon transection compared with wild-type mice, suggesting MMP-2 plays an important role in muscle atrophy. Although the exact mechanisms remain unknown, a newly-discovered intracellular form of MMP-2 suggests a possible novel mechanism of MMP-2 digesting muscle matrix during muscle atrophy. I propose a new pharmacologic treatment for muscle atrophy using selective MMP-2 inhibitors.

Anabolic Agents and Bone Quality

Tarek Sibai MD, Elise F. Morgan PhD, Thomas A. Einhorn MD

The definition of bone quality is evolving particularly from the perspective of anabolic agents that can enhance not only bone mineral density but also bone microarchitecture, composition, morphology, amount of microdamage, and remodeling dynamics.

Cartilage-mimicking, High-density Brush Structure Improves Wear Resistance of Crosslinked Polyethylene: A Pilot Study

Masayuki Kyomoto PhD, Toru Moro MD, Yoshio Takatori MD, Hiroshi Kawaguchi MD, Kazuhiko Ishihara PhD

In natural synovial joints under physiologic conditions, fluid thin-film lubrication by a hydrated layer of the cartilage is essential for the smooth motion of the joints. The considerably less efficient lubrication of artificial joints of polyethylene is prone to wear, leading to osteolysis and aseptic loosening and limiting the longevity of THA. A nanometer-scale layer of poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC) with cartilage-mimicking brushlike structures on a crosslinked polyethylene (CLPE) surface may provide hydrophilicity and lubricity resembling the physiologic joint surface.

Vitamin E-stabilized UHMWPE for Total Joint Implants: A Review

Pierangiola Bracco MD, Ebru Oral PhD

Osteolysis due to wear of UHMWPE limits the longevity of joint arthroplasty. Oxidative degradation of UHMWPE gamma-sterilized in air increases its wear while decreasing mechanical strength. Vitamin E stabilization of UHMWPE was proposed to improve oxidation resistance while maintaining wear resistance and fatigue strength.

Crack Propagation Resistance Is Similar Under Static and Cyclic Loading in Crosslinked UHMWPE: A Pilot Study

Jevan Furmanski PhD, Clare M. Rimnac PhD

Recent work suggests crack phenomena (eg, crack initiation and propagation) in UHMWPE do not depend on cyclic damage mechanisms. Materials for which crack phenomena occur in static (noncyclic) mode should exhibit similar crack propagation behavior under static and cyclic loading conditions.

Emerging Ideas: The Effect of Hypercholesterolemia on Tendons

Joseph A. Abboud MD, David P. Beason MS, Louis J. Soslowsky PhD

High levels of total cholesterol, triglycerides, and low-density lipoprotein are toxic to the vascular endothelium and thus have long been associated with atherosclerosis. Several clinical studies have suggested that elevated cholesterol also has a negative effect on tendon structure and function. Data from our preliminary studies show that the patellar tendons of hypercholesterolemic knockout mice exhibit reduced baseline elastic modulus and strength postinjury compared with controls.

Emerging Ideas: Prevention of Posttraumatic Arthritis Through Interleukin-1 and Tumor Necrosis Factor-alpha Inhibition

J. Todd R. Lawrence MD, PhD, James Birmingham MD, Alison P. Toth MD

Despite surgical and mechanical stabilization of an acutely injured joint through ligament reconstruction, meniscus repair, or labral repair, the risk of posttraumatic arthritis remains high. Joint injury triggers three phases of pathogenic events: the early (acute) phase involves joint swelling, hemarthrosis, expression of inflammatory cytokines (especially interleukin-1 [IL-1] and tumor necrosis factor-α [TNF-α]), and biomarkers of cartilage catabolism; an intermediate phase is characterized by reduction of joint inflammation, ongoing joint catabolism, but no evidence yet for typical features of radiographic osteoarthritis (OA); and a late phase characterized by radiographic OA.

Raman Assessment of Bone Quality

Michael D. Morris PhD, Gurjit S. Mandair PhD

Progress in the diagnosis and prediction of fragility fractures depends on improvements to the understating of the compositional contributors of bone quality to mechanical competence. Raman spectroscopy has been used to evaluate alterations to bone composition associated with aging, disease, or injury.

Emerging Ideas: Interleukin-12 Nanocoatings Prevent Open Fracture-associated Infections

Bingyun Li PhD, Anne L. McKeague PhD

Infection is a major clinical complication of orthopaedic implants and prosthetic devices, and patients with traumatic open fractures have a high risk of infection that may exceed 30%. Surgical trauma, burns, and major injuries such as traumatic open fractures induce immunosuppression, decrease resistance to infection, and decrease production of T helper type 1 (Th1) cytokines.

Emerging Ideas: Soft Tissue Applications of Radiostereometric Analysis

Lucian B. Solomon MD, PhD, FRACS, Stuart A. Callary BAppSc

Currently, the movement that occurs at the site of soft tissue repair cannot be measured accurately in vivo. Radiostereometric analysis (RSA) is the gold standard for measuring movement between two skeletal segments in vivo but its application to studying soft tissue migration has been limited by the unknown stability of tantalum beads in tendons and ligaments and their ability to define rigid bodies in these structures.