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Query: UNIPROT:P50502 (Hip)
 7,003 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

An interactive computer program was developed to derive femoral neck geometry from raw bone mineral image data for an estimate of hip strength using single plane engineering stress analysis. The program, which we call Hip Strength Analysis (HSA), was developed as an attempt to improve the predictive value of hip bone mineral data for osteoporosis fracture risk assessment. We report a series of experiments with an aluminum phantom and with cadaver femora, designed to test the accuracy of derived geometric measurements and strength estimates. Using data acquired with both Lunar DP3 (DPA) and Hologic QDR-1000 (x-ray) scanners, HSA computed femoral neck cross-sectional areas (CSA) and cross-sectional moments of inertia (CSMI) on an aluminum phantom were in excellent agreement with actual values (r greater than .99). Using Lunar DP3 data, CSA and CSMI measurements at mid-femoral necks of 22 cadaver specimens were in good general agreement with literature values. HSA computed cross-sectional properties of three of these specimens were compared with measurements derived from sequential CT cross-sectional images. Discrepancy between the two methods averaged less than 10% along the length of the femoral neck. Finally, breaking strengths of 20 of the femora were measured with a materials testing system, showing better agreement with HSA predicted strength (r = .89, percent standard of the estimate (%SEE) = 21%) than femoral neck bone mineral density (r = .79, %SEE = 28%).
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PMID:Predicting femoral neck strength from bone mineral data. A structural approach. 229 52

Seventeen Arabian weanlings were used to determine the influence of housing on third metacarpal bone mass. Animals were separated into three treatment groups: Pasture (n = 6), Stall (n = 5), and Partial-Pasture (n = 6). Radiographs of the left third metacarpus were taken every 28 d to determine radiographic bone aluminum equivalence (RBAE). Serum was collected every 14 d and analyzed for osteocalcin, carboxyterminal telopeptide of type I collagen (ICTP), and keratan sulfate. Hip and wither height, BW, and cannon circumference were measured every 28 d. Lateral RBAE in the pastured group increased linearly from d 0 to d 56 (P = 0.001). In the Pasture group, total RBAE increased from d 0 to 56 (P = 0.05) and medial RBAE tended to increase from d 0 to d 28 (P = 0.06). The Partial Pasture group increased from d 0 to 56 in medial (P = 0.02) and tended to increase in total RBAE (P = 0.08). Although the Stall group demonstrated an increase in total RBAE from d 0 to 56 (P = 0.04), the Partial Pasture group tended to have greater total RBAE than the Stall group at d 28 (P = 0.08), and the Pasture group had greater lateral RBAE at d 28 (P = 0.005) and 56 (P = 0.007) than did the Stall group. At d 28, medial RBAE was greater in the Pasture (P = 0.003) and Partial Pasture (P = 0.05) groups than in the Stall group. Pasture and Stall groups tended to decrease in osteocalcin (P = 0.06), whereas Partial Pasture weanlings decreased (P = 0.01) from d 0 to 56. All treatment groups decreased from d 0 to 56 in ICTP (P < 0.01). Pastured weanlings decreased from d 0 to 42 in serum keratin sulfate (P < 0.05), whereas the Stall group decreased from d 0 to 56 (P = 0.05). All treatment groups increased in wither height (P < or = 0.01), hip height (P < or = 0.001), and BW (P < or = 0.01). Both the Pasture and Partial Pasture weanlings demonstrated greater cannon circumference than Stall weanlings on d 28 (P < or = 0.05) and 56 (P < or = 0.005). These data demonstrate that pasture rearing or 12-h daily turnout is beneficial to maintaining and increasing bone mineral content in weanling Arabian horses.
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PMID:Daily access to pasture turnout prevents loss of mineral in the third metacarpus of Arabian weanlings. 1137 32

Bearings made of ceramics have ultra-low wear properties that make them suitable for total hip arthroplasty (THA) and total knee arthroplasty (TKA). When compared to cobalt chrome (CoCr)-on-polyethylene (PE) articulations, ceramics offer drastic reductions in bearing wear rates. Lower wear rates result in fewer wear particles produced by the articulating surfaces. In theory, this should reduce the risk of periprosthetic osteolysis and premature implant loosening, thereby contributing to the longevity of total joints. In addition to ceramics, other alternative bearing couples, such as highly cross-linked PE (XLPE) and metal-on-metal also offer less wear than CoCr-on-PE articulations in total joint arthroplasty. Alumina and zirconia ceramics are familiar to orthopaedic surgeons since both materials have been used in total joints for several decades. While not new in Europe, alumina-on-alumina ceramic total hips have only recently become available for widespread use in the United States from various orthopaedic implant manufacturers. As the search for the ideal total joint bearing material continues, composite materials of existing ceramics, metal-on-ceramic articulations, and new ceramic technologies will offer more choices to the arthroplasty surgeon. The objective of this paper is to present an overview of material properties, clinical applications, evolution, and limitations of ceramic materials that are of interest to the arthroplasty surgeon.
Hip Int
PMID:A review of ceramic bearing materials in total joint arthroplasty. 1919 39

We performed a study to assess whether different bearing materials have an impact on femoral bone remodeling within the first four years after a hybrid total hip arthroplasty. 205 of 300 patients were available for 4 years follow-up after being randomly allocated to four prosthetic combinations: A: Zirconia ceramic head, polyethylene cup; B: Cobalt-Chrome-Molybdenum head and cup; C: Zirconia ceramic head, polyethylene moulded on the Titanium shell of the Asian cup; D: Alumina head and cup. Bone mineral density (BMD) was measured with Dual-Energy X-ray Absorptiometry in seven Gruen zones adjacent to the femoral implant. Scans were performed within one week after surgery and four years postoperatively. Clinical outcomes were monitored using the Oxford Hip Score (OHS). A high proportion of patients from group D were excluded due to re-operations (19 patients). BMD decreased significantly in all Gruen zones with the largest declines in group D. BMD changes in Gruen zones 1, 2, 3, 6, and 7 correlated with height, and body weight. Advanced age was associated with an increase in bone loss in Gruen zones 1, 2, 3, 6, and 7. A large stem size was associated with a decline in BMD in Gruen zones 1, 6, and 7.Bone remodeling after total hip arthroplasty may depend on the composition of bearing materials, but age, height, weight, and stem size are also related to changes in BMD.
Hip Int
PMID:A prospective randomised study of periprosthetic femoral bone remodeling using four different bearings in hybrid total hip arthroplasty. 2148 44

Alumina grit-blasted implants have been widely used in cementless total hip arthroplasty (THA). However, alumina particles can become embedded in the implant surface, leading to deposition in periprosthetic tissues and implant wear. We hypothesised that the alumina-reduced surface BICON-PLUS NT acetabular cup would improve implant fixation and clinical outcomes over the conventional surface BICON-PLUS cup. In a randomised controlled, double-blind study, patients with primary or secondary osteoarthritis requiring primary arthroplasty were randomly assigned to THA with either the BICON-PLUS or BICON-PLUS NT cup. All cups were combined with the SL-PLUS stem. In addition to clinical and radiographic assessments, dual-energy X-absorptiometry (DEXA) was performed preoperatively and at regular intervals during a planned 2-year follow-up period to measure bone mineral density as a marker of implant fixation. At 1 year, there were no differences in bone mineral density, or in clinical or radiographic outcomes between the BICON-PLUS and BICON-PLUS NT groups were identified, leading to early termination of the study. Both groups showed excellent clinical improvement and there were few complications. Both the alumina-reduced and conventional surface acetabular cups can be used with confidence in primary THA for osteoarthritis, although longer-term studies are required to confirm these findings.
Hip Int
PMID:Comparing alumina-reduced and conventional surface grit-blasted acetabular cups in primary THA: early results from a randomised clinical trial. 2274 Feb 83

;There is now considerable clinical concern about the effect of polyethylene wear debris induced osteolysis in long term failure of hip replacements. This paper compares the wear of stabilised and crosslinked polyethylene to alternative hard on hard bearings. The volumetric wear rates of stabilised and moderately crosslinked polyethylene 50 to 35 mm<sup>3</sup>/million cycles were less than previously reported for historical gamma irradiated in air polyethylene, but still of a level that in the long term could cause osteolysis. The moderately crosslinked polyethylene produced less wear than non-crosslinked polyethylene, but particles were smaller and more reactive resulting in little change in the osteolytic potential. Alumina ceramic on ceramic produced substantially less wear and osteolytic potential. Metal on metal also produced less wear than polyethylene but the particles adversely influence cell viability.
Hip Int 2003 Mar 15
PMID:Alternative bearing couples in total hip replacements: Solutions for young patients. 2403 May 81