Journal of orthopaedic research : official publication of the Orthopaedic Research Society
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Biomechanical properties of healthy and degenerated nucleus pulposus (NP) are thought to be important for future regenerative strategies for intervertebral disc (IVD) repair. However, which properties are pivotal as design criteria when developing NP replacement materials is ill understood. Therefore, we determined and compared segmental biomechanics and NP viscoelastic properties in normal and mildly degenerated discs. ⋯ Relative water content in the NP was unaffected by CABC, remaining at ∼75%. These observations suggest that viscoelastic properties have a marginal influence on mechanical behavior of the whole SMS. Therefore, when developing replacement materials the focus should be on other design criteria, such as biochemical cues and swelling pressure.
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Outcomes following the open reduction and internal fixation (ORIF) of displaced acetabular fractures in the elderly have been inconsistent. Several factors associated with significant poor clinical outcomes have been reported; however, the factor that contributes independently to the outcomes remains unknown. This study aims to identify independent prognostic factors for the outcomes of surgically treated displaced acetabular fractures in the elderly. ⋯ Multivariate analysis identified three independent predictors of clinical outcomes: reduction grades (t = -10.45, p = 0.000), CPWF (t = -2.74, p = 0.008), and FHI (t = -3.51, p = 0.000). Both CPWF and FHI are important risk factors for clinical outcome. The postoperative quality of reduction independently predicted patient prognosis, and anatomical reduction is predictive of a good prognosis.
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Double fusion (i.e., fusion of the subtalar and talonavicular joint) represents a modification of triple arthrodesis preserving integrity of the calcaneocuboidal joint. Our aims were (1) to evaluate dynamic plantar pressure distribution in patients undergoing double arthrodesis, (2) to obtain a comparison of kinematic changes to healthy feet, (3) to evaluate the influence of radiographic alignment, and (4) to assess functional outcome. Sixteen feet (14 patients) treated by double fusion due to fixed planovalgus deformity were included. ⋯ The pre- and post-operative AOFAS score increased from 37 points (SD, 16.3) to 70 points (SD, 16.7). These results revealed that double arthrodesis represents a reliable method for correction of planovalgus deformity. Compared with healthy feet, force transmission of the midfoot is increased whereas push-off force decreases.
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Carbon fiber-reinforced polyetheretherketone (CFR/PEEK) is theoretically suitable as a material for use in hip prostheses, offering excellent biocompatibility, mechanical properties, and the absence of metal ions. To evaluate in vivo fixation methods of CFR/PEEK hip prostheses in bone, we examined radiographic and histological results for cementless or cemented CFR/PEEK hip prostheses in an ovine model with implantation up to 52 weeks. CFR/PEEK cups and stems with rough-textured surfaces plus hydroxyapatite (HA) coatings for cementless fixation and CFR/PEEK cups and stems without HA coating for cement fixation were manufactured based on ovine computed tomography (CT) data. ⋯ Our results suggest that both cementless and cemented CFR/PEEK stems work well for fixation. Cup fixation may be difficult for both cementless and cemented types in this ovine model, but bone ongrowth fixation on the cup was first seen in two cementless cases. Cementless fixation can be achieved using HA-coated CFR/PEEK implants, even under load-bearing conditions.
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We tested the hypothesis that immediate reattachment of the native anterior cruciate ligament (ACL) can prevent kinematic changes and the development of osteoarthritis (OA). Five sheep underwent anatomic unilateral ACL reconstruction (ACL-R). Animals from a previous study served as sham (n = 7) or non-operated (n = 17) controls. ⋯ At 20 weeks, differential scores showed that sham operated joints were morphologically indistinguishable from non-operated controls (p ≥ 0.129) while ACL-R joints had significantly higher combined cartilage and osteophyte scores than those controls (p ≤ 0.003). This method of ACL reconstruction in sheep did not restore normal walking gait kinematics completely and allowed some OA to develop in operated joints. OA may result from relatively subtle mechanical abnormalities, apparently more so in some individuals than others.