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

The application of a thin coating of hydroxylapatite to total hip implants has provided the opportunity to realize stable fixation of a press-fit prosthesis without a porous coating or an intervening fibrous tissue layer. This series consists of 436 total hip arthroplasties, of which 320 cases have a minimum two-year follow-up period and 142 cases have a minimum three-year follow-up period. The femoral prosthesis used was a roughened titanium alloy with a 50-microns surface treatment of hydroxylapatite applied to the proximal one third. The acetabular components implanted included porous-coated implants (132), hydroxylapatite-coated acetabular shells of varying geometries (285), and bipolar implants (16). Analysis of the clinical results demonstrates a mean Harris Hip Score of 93 at six-months postarthroplasty, 95 at one and two years, and 96 at three years. At the three-year follow-up evaluation, 4.2% of patients complained of mild to moderate pain in the operative limb, whereas only 2.2% at two years and 1.4% at three years complained of activity-related thigh pain. The femoral mechanical loosening rate representing stems revised for aseptic loosening (two) plus roentgenographically unstable stems (zero) is 0.46%. Three hydroxylapatite-coated acetabular cups (1%) have shown measurable migration at two years, but none have been revised for aseptic loosening. The roentgenographic evaluation provides evidence for excellent proximal femoral fixation with distal stress transfer. Radiolucencies typically occur around the uncoated distal tip of the femoral stem (74%), but rarely in the proximal hydroxylapatite-coated anterior (3%) and lateral (2%) zones. Femoral cancellous condensation characteristically is seen at the transition zone of hydroxylapatite coated-to-uncoated stems (86%), whereas up to 32% of cases show cortical hypertrophy at the medial distal stem. These roentgenographic changes are progressive from one through three years postoperatively.
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PMID:Hydroxylapatite-coated hip implants. Multicenter three-year clinical and roentgenographic results. 144 26

In March, 1981, development of a hip socket for implantation without the use of bone cement was begun in the Biomechanics Research Laboratory of the Department of Orthopaedic Surgery of the University of Zurich, Balgrist. Already in March, 1982, the first artificial socket with selflocking action, the Balgrist Hip Socket, was successfully implanted in a patient. Following some design modifications, a series of 287 hip sockets were implanted before April, 1986; all of them being made entirely of high density polyethylene. In an attempt to improve the anchoring of the prosthesis within the bone, the outer surface of polyethylene that faced the bone was furnished with a thin coating of titanium and in this form the socket was used 63 times. In the meantime, a model with the outer split shell made of titanium was designed so that in this presently used form, from November, 1987, up to August, 1989, 133 of these hip sockets have been implanted. With the removal or replacement of only 29 sockets, which amounts to 6% (2.7% aseptic and 0.8% septic loosenings, 1.3% removed because of technical mistakes made in the early stages, and 1.3% removed because of suspected low grade infection) the results up to now might well be considered most encouraging.
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PMID:[The self-locking Balgrist hip socket for cement-free fixation--history of its development and clinical experience to date]. 214 72

The efficacy of using hydroxyapatite/tricalcium phosphate (HAP/TCP) particles to enhance the biological fixation of a canine cementless femoral component with a noninterference fit was evaluated with a custom-designed collarless, wedge-shaped femoral component with titanium fiber metal pads along the anteroposterior surfaces of the stem. A polyethylene acetabular component was cemented into the pelvis. Three groups of dogs were employed: group I (n = 7) had a femoral component with an interference fit; group II (n = 6) had a component with a noninterference fit with uniform voids along the anteroposterior stem surfaces; and group III (n = 6) had a component with a noninterference fit including uniform voids filled with HAP/TCP particles. All dogs were harvested after 12 weeks of unrestricted weight bearing. Cross-section specimens from three different levels from each bone-component composite were evaluated histologically to determine the type and extent of tissue ingrowth and the percentage of peripheral bone or HAP/TCP particles adjacent to the fiber metal pad surfaces. Three other cross-section specimens, adjacent to the histological section levels of the same composites, were assessed for shear strength at the fiber metal-tissue interface and for biochemical composition of the ingrown tissue.
Hip 1987
PMID:The John Charnley Award paper. Efficacy of using a bone graft substitute to enhance biological fixation of a porous metal femoral component. 381 46

Recently the operative techniques, instrumentation, design, and material properties of bony ingrowth total hip replacement have been greatly improved. I prefer a hemispherical acetabular component fixed with screws going through the metal shell. The titanium mesh allows microinterlock with new bone, and macrointerlock is obtained by adding bone graft into the unused screw holes. The femoral component, made of Tivanium with titanium mesh attached to it by a new process called diffusion bonding, retains superalloy fatigue strength characteristics. An intimate press fit is assured by the specific operative technique, and both the fiber mesh and the collar provide proximal stress transfer. The design affords a nondestructive method for removal if necessary. The short-term clinical results are promising; most patients function as well as with cemented total hip replacement. The incidence of thigh pain has been significantly reduced since prior reports of cementless total hip replacement; however, a few patients still have thigh pain. The results in revision surgery are also promising, but as in cemented total hip replacement, the functional capacity of revision cases is usually lower than primary cases. There is an increased capacity to correct complex and difficult acetabular problems with this acetabular component. Obviously, long-term data are needed to establish the behavior of these implants over the immediate and long term.
Hip 1987
PMID:Current status of noncemented hip implants. 381 49

In an attempt to overcome the problem of micromotion between implant and bone and to eliminate the deleterious effects of polyethylene wear particles, I developed large, flat, hollow cylinders with perforated walls through which lamellar bone growth rapidly occurs. These cylinders were combined with self-cutting, prestressed spherical rings of pure titanium. Metallic sockets and heads coated with 4 to 6 microns of titanium nitrite and titanium carbide were created to fit a cementless straight stem and the cementless acetabular implant. The system is in clinical evaluation.
Hip 1985
PMID:A new concept of acetabular fixation. 383 Sep 89

Hip replacement stems manufactured from Ti6Al4V titanium alloy were surface treated in one of four ways and tested for dissolution resistance in bovine serum. Those stems treated thermally were found to have significantly lower metal ion release compared with those receiving standard commercial treatments. The improved dissolution behaviour is associated with a change in the surface oxide structure from mixed titanium oxides to a more stable rutile structure.
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PMID:Surface modification of titanium alloy implants. 783 36

A review of 52 cementless revision total hip arthroplasties in 51 patients with a 4- to 6-year clinical and radiographic followup was conducted. Mallory Head titanium alloy prostheses using proximally porous-coated femoral stems were used in all cases. There were 2 revisions of the femoral component only and 1 was an acetabular revision. At an average followup of 4.6 years, 5 (10%) unstable femoral stems had been rerevised and another 7 (14%) stems were unstable radiographically, but rerevision had been refused or postponed. Three (6%) sockets were considered unstable but no acetabular revisions have been done. Eleven of the 12 stem failures were in femora with moderate or severe prerevision femoral bone loss. The Harris Hip Score averaged 76 points for the entire group, and scores were much worse in patients with preexisting femoral bone deficiency. Twenty (40%) femoral fractures occurred during stem insertion. This short-term study shows inadequate fixation of proximally porous-coated femoral stems in revisions with femoral bone loss; adequate stability is achieved if bone loss is limited. Porous-coated acetabular fixation using fins and screws where necessary is adequate in the majority of cases.
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PMID:Uncemented revision total hip arthroplasty: a 4-to-6-year review. 899 68

Hip-simulator studies were carried out to investigate the initial wear between a femoral head made of aluminium oxide ceramic and a CFRP-(carbon fibre-reinforced plastic) inlay in a titanium cup. A load of 2500 N and a frequency of 0.857 Hz were applied. After 200,000 cycles, the centre of the head had moved 9 microns into the liner. After 500,000 cycles, the cup centre had moved inwards by a further micron, and the near radius had increased by 2 microns. After 750,000 cycles the position of the centre of the head remained unchanged, while the mean radius had increased a further 2 microns. After one million cycles any further changes remained below the measuring capability (1 micron) of the system.
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PMID:[Wear behavior of coupled aluminum oxide ceramics-carbon fiber bond as hip acetabulum inlay in a simulated trial]. 910 55

Two hundred three consecutive primary uncemented total hip arthroplasties were prospectively randomized using collared and collarless versions of an identical titanium stem. Identical 28-mm titanium heads were implanted in all cases. One hundred three collared hips were compared with 100 collarless hips. Follow-up periods averaged 45.7 months in both groups. Intraoperative, early, and late complications were similar. Hip scores, including thigh pain, at final follow-up visit were also similar. No significant differences were noted in acetabular or femoral radiolucencies, subsidence, osteolysis, or proximal femoral remodeling. At 5 years, more collarless stems revealed pedestal formation (57.1% vs 33.9%). The presence of a collar had no effect on the adequacy of fixation, proximal femoral osteopenia, or clinical scores at 5 years.
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PMID:Comparison of collared and collarless femoral components in primary uncemented total hip arthroplasty. 911 41

Few guidelines are currently available to the surgeon when choosing a specific femoral component for cementless total hip replacement (THR). A survey of the members of the American Association for Hip and Knee Surgeons (AAHKS) was conducted to gain insight into the importance of implant material, stress shielding, and micromotion in the selection of cementless femoral components. A comprehensive survey was distributed to 300 orthopedic surgeons selected from the members of the AAHKS; 169 of the 300 surgeons completed the detailed questionnaire. The results of the survey were analyzed using the SPSS software package to obtain general trends in opinion, and a stepwise regression analysis was used to correlate responses with training and clinical experience. Interestingly, there was little consensus among surgeons with respect to the relative importance of implant material, stress shielding, and micromotion in the selection of prostheses for cementless THR. In general, bone loss secondary to stress shielding was the least important issue, and axial and rotational micromotion were considered progressively more significant problems. Cementless titanium alloy stems were perceived as offering no significant advantage over cobalt chrome alloy stems. Moreover, there was no consensus as to whether a collar was advantageous. Prosthesis stability, restoration of motion, and a proven clinical record were more important to surgeons than were ease of implantation and removal, cost, and availability.
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PMID:Design of the femoral component for cementless hip replacement: the surgeon's perspective. 919 93


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