Browsing by Subject "Tibia"

Filter results by typing the first few letters
Now showing 1 - 2 of 2
  • Thumbnail Image
    ItemOpen Access
    Cartilage mechanics in the guinea pig model of osteoarthritis studied with an osmotic loading method.
    (Osteoarthritis and cartilage, 2004-05) Flahiff, Charlene M; Kraus, Virginia B; Huebner, Janet L; Setton, Lori A
    To determine the material properties of articular cartilage in the Hartley guinea pig model of spontaneous osteoarthritis.Cartilage-bone samples from the medial femoral condyle and tibial plateau of 12 month-old guinea pig knees were subjected to osmotic loading. Site-matched swelling strains and fixed charge density values were used in a triphasic theoretical model for cartilage swelling to determine the modulus of the cartilage solid matrix. The degree of cartilage degeneration was assessed in adjacent tissue sections using a semi-quantitative histological grading scheme.Decreased values for both moduli and surface zone fixed charge density were associated with increasing grades of cartilage degeneration. Decreases in moduli reflect damage to the collagen matrix, which give rise to greater swelling strains.Histological evidence of cartilage degeneration was associated with impaired cartilage mechanics in the aging Hartley guinea pig.
  • Thumbnail Image
    ItemOpen Access
    Comparison of extramedullary versus intramedullary referencing for tibial component alignment in total ankle arthroplasty.
    (Foot Ankle Int, 2013-12) Adams, Samuel B; Demetracopoulos, Constantine A; Viens, Nicholas A; DeOrio, James K; Easley, Mark E; Queen, Robin M; Nunley, James A
    BACKGROUND: The majority of total ankle arthroplasty (TAA) systems use extramedullary alignment guides for tibial component placement. However, at least 1 system offers intramedullary referencing. In total knee arthroplasty, studies suggest that tibial component placement is more accurate with intramedullary referencing. The purpose of this study was to compare the accuracy of extramedullary referencing with intramedullary referencing for tibial component placement in total ankle arthroplasty. METHODS: The coronal and sagittal tibial component alignment was evaluated on the postoperative weight-bearing anteroposterior (AP) and lateral radiographs of 236 consecutive fixed-bearing TAAs. Radiographs were measured blindly by 2 investigators. The postoperative alignment of the prosthesis was compared with the surgeon's intended alignment in both planes. The accuracy of tibial component alignment was compared between the extramedullary and intramedullary referencing techniques using unpaired t tests. Interrater and intrarater reliabilities were assessed with intraclass correlation coefficients (ICCs). RESULTS: Eighty-three tibial components placed with an extramedullary referencing technique were compared with 153 implants placed with an intramedullary referencing technique. The accuracy of the extramedullary referencing was within a mean of 1.5 ± 1.4 degrees and 4.1 ± 2.9 degrees in the coronal and sagittal planes, respectively. The accuracy of intramedullary referencing was within a mean of 1.4 ± 1.1 degrees and 2.5 ± 1.8 degrees in the coronal and sagittal planes, respectively. There was a significant difference (P < .001) between the 2 techniques with respect to the sagittal plane alignment. Interrater ICCs for coronal and sagittal alignment were high (0.81 and 0.94, respectively). Intrarater ICCs for coronal and sagittal alignment were high for both investigators. CONCLUSIONS: Initial sagittal plane tibial component alignment was notably more accurate when intramedullary referencing was used. Further studies are needed to determine the effect of this difference on clinical outcomes and long-term survivability of the implants. LEVEL OF EVIDENCE: Level III, retrospective comparative study.