title: The mechanics of focal chondral defects in the hip.
abstract: There is a mean incidence of osteoarthritis (OA) of the hip in 8% of the overall population. In the presence of focal chondral defects, defined as localized damage to the articular cartilage, there is an increased risk of symptomatic progression toward OA. This relationship between chondral defects and subsequent development of OA has led to substantial efforts to develop effective procedures for surgical cartilage repair. This study examined the effects of chondral defects and labral delamination on cartilage mechanics in the dysplastic hip during the gait cycle using subject-specific finite element analysis. Models were generated from volumetric CT data and analyzed with simulated chondral defects at the chondrolabral junction on the posterior acetabulum during five distinct points in the gait cycle. Focal chondral defects increased maximum shear stress on the osteochondral surface of the acetabular cartilage, when compared to the intact case. This effect was amplified with labral delamination. Additionally, chondral defects increased the first principal Lagrange strain on the articular surface of the acetabular cartilage and labrum. Labral delamination relieved some of this tensile strain. As defect size was increased, contact stress increased in the medial zone of the acetabulum, while it decreased anteriorly. The results suggest that in the presence of chondral defects and labral delamination the cartilage experiences elevated tensile strains and shear and contact stress, which could lead to further damage of the cartilage, and subsequent arthritic progression. The framework presented here will serve as the procedure for future finite element studies on cartilage mechanics in hips with varying disease states with simulated chondral defects and labral tears.
authors.affiliation: Department of Bioengineering, University of Utah, 36 S. Wasatch Drive, Rm. 3100, Salt Lake City, UT 84112, United States; Scientific Computing and Imaging Institute, University of Utah, 72 S. Central Campus Drive, Salt Lake City, UT 84112, United States.
authors.forename: Brenden J
authors.initials: BJ
authors.lastname: Klennert
authors.affiliation: Department of Bioengineering, University of Utah, 36 S. Wasatch Drive, Rm. 3100, Salt Lake City, UT 84112, United States; Scientific Computing and Imaging Institute, University of Utah, 72 S. Central Campus Drive, Salt Lake City, UT 84112, United States.
authors.forename: Benjamin J
authors.initials: BJ
authors.lastname: Ellis
authors.affiliation: Department of Orthopaedics, University of Utah, 590 Wakara Way, Salt Lake City, UT 84108, United States.
authors.forename: Travis G
authors.initials: TG
authors.lastname: Maak
authors.affiliation: Department of Orthopaedics, University of Utah, 590 Wakara Way, Salt Lake City, UT 84108, United States.
authors.forename: Ashley L
authors.initials: AL
authors.lastname: Kapron
authors.affiliation: Department of Bioengineering, University of Utah, 36 S. Wasatch Drive, Rm. 3100, Salt Lake City, UT 84112, United States; Scientific Computing and Imaging Institute, University of Utah, 72 S. Central Campus Drive, Salt Lake City, UT 84112, United States; Department of Orthopaedics, University of Utah, 590 Wakara Way, Salt Lake City, UT 84108, United States. Electronic address: jeff.weiss@utah.edu.
authors.forename: Jeffrey A
authors.initials: JA
authors.lastname: Weiss
mesh_terms: D000077:Acetabulum / Q000503:physiopathology; D000328:Adult; D002358:Cartilage, Articular / Q000293:injuries / Q000503:physiopathology*; D005260:Female; D020342:Finite Element Analysis; D005684:Gait / Q000502:physiology; D006617:Hip Dislocation / Q000503:physiopathology*; D006621:Hip Joint / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008954:Models, Biological; D013314:Stress, Mechanical; D055815:Young Adult
keywords: Cartilage mechanics; Chondral defect; Finite element; Hip; Labral tear