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At least 649 records · Page 36Linked to original sources
PubMed1988

Three-dimensional geometric analysis of the metacarpophalangeal joint.

No prosthesis yet designed for replacement of the metacarpophalangeal (MCP) joint incorporates all considerations of anatomy and geometry of the natural joint to restore the normal kinematics. Loss of stability, recurrent deformity, and early loosening are persistent problems. In this study, a detailed three-dimensional geometric analysis of the MCP joint was performed. The sagittal contours of both metacarpal heads and base of the proximal phalanx under loaded and unloaded conditions were analyzed. The geometric parameters of the MCP joint articulating surfaces were analyzed, including the center and radius of curvature and the location and size of the contact area. The pressures on articulating surfaces during various hand functions were also established. These findings provided important information for better understanding the kinematics of finger joint articulation, as well as the cause of joint degeneration.

Adult↗
PubMed1985

[Reconstruction of the temporomandibular joint with a total intermediate prosthesis].

A method for reconstruction of temporomandibular joint is proposed using an intermediary prosthesis and non-sealed cupula. This prosthesis respects the cranial articular slope and provides twofold mobility at the cupular level, which approaches physiological conditions and allows reproduction of buccal opening and closing movements as well as lateralization. A strict surgical procedure is essential when inserting the prosthesis, particular care being necessary in the approach to the facial nerve and control of its temporofacial contingent until above the zygomatic arch. Indications for this procedure are discussed in relation to injuries and tumoral, degenerative and malformatory lesions.

Ankylosis↗
PubMed1989

Implant arthroplasty: still a consideration.

The Keller arthroplasty has long been the hallmark of first metatarsophalangeal joint corrections. However, in the presence of adverse postoperative effects, numerous modifications have been introduced. They include preoperative evaluation, soft-tissue and osseous techniques in the procedure itself, and postoperative care of the patient. These modifications have created a new and improved Keller arthroplasty.

Humans↗
PubMed1978

Patellar fracture after replacement of the tibio-femoral joint with the ICLH prosthesis.

Four cases are reported of spontaneous fracture of the patella after ICLH replacement of the knee for Rheumatoid Arthritis. Three of these occur-red in patellae that had not themselves been replaced; one in a resurfaced patella. The former required no specific treatment but the latter required revision surgery. It is argued that the existence of this complication may represent a contra-indication to patellar replacement in the osteoporotic rheumatoid knee.

Arthritis, Rheumatoid↗
PubMed2002

A literature review of "failures" of the Swanson finger prosthesis in the metacarpophalangeal joint.

This paper reviews the use of the Swanson finger prosthesis, concentrating on clinical results from the metacarpophalangeal (MCP) joint and modes of prosthetic "failure". While "failure" is generally associated with fracture, it is recognised that fracture does not always necessitate replacement of the Swanson prosthesis. Fracture tends to occur at the junction of the distal stem and hinge of the prosthesis. Initial improvements in ulnar deviation and range of motion (ROM) tend to be gradually reduced over the duration of implantation, and there is little evidence to suggest any long-term improvement in hand strength. Bone erosion and silicone synovitis have been seen but at a much lesser incidence than in other joints implanted with silicone spacers. An evaluation of retrieved Swanson prostheses, tied in with patient history and hand measurements might provide additional information to improve the design of the Swanson prosthesis itself and of other finger prostheses.

Arthritis↗
PubMed1992

Tissue ingrowth into titanium and hydroxyapatite-coated implants during stable and unstable mechanical conditions.

Lack of initial mechanical stability of cementless prostheses may be responsible for fibrous tissue fixation of prosthetic components to bone. To study the influence of micromovements on bony ingrowth into titanium alloy (Ti) and hydroxyapatite (HA)-coated implants, a loaded unstable device producing movements of 500 microns during each gait cycle was developed. Mechanically stable implants served as controls. The implants were inserted into the weight-bearing regions of all four femoral condyles in each of seven mature dogs. Histological analysis after 4 weeks of implantation showed a fibrous tissue membrane surrounding both Ti and HA-coated implants subjected to micromovements, whereas variable amounts of bony ingrowth were obtained in mechanically stable implants. The pushout test showed that the shear strength of unstable Ti and HA implants was significantly reduced as compared with the corresponding mechanically stable implants (p less than 0.01). However, shear strength values of unstable HA-coated implants were significantly greater than those of unstable Ti implants (p less than 0.01) and comparable to those of stable Ti implants. The greatest shear strength was obtained with stable HA-coated implants, which was threefold stronger as compared with the stable Ti implants (p less than 0.001). Quantitative determination of bony ingrowth agreed with the mechanical test except for the stronger anchorage of unstable HA implants as compared with unstable Ti implants, where no difference in bony ingrowth was found. Unstable HA-coated implants were surrounded by a fibrous membrane containing islands of fibrocartilage with higher collagen concentration, whereas fibrous connective tissue with lower collagen concentration was predominant around unstable Ti implants. In conclusion, micromovements between bone and implant inhibited bony ingrowth and led to the development of a fibrous membrane. The presence of fibrocartilage and a higher collagen concentration in the fibrous membrane may be responsible for the increased shear strength of unstable HA implants. Mechanically stable implants with HA coating had the strongest anchorage and the greatest amount of bony ingrowth.

Analysis of Variance↗
PubMed1996

Instrumented implant for measuring tibiofemoral forces.

Experimental measurement of loads occurring in the human knee joint will allow validation of analytical models and provide data for the design of total knee implants. A customized transducer was developed to measure the dynamic tibiofemoral force and center of pressure after total knee arthroplasty. The transducer consists of a standard tibial component to which four uniaxial load cells and an additional tibial tray have been added. The transducer was calibrated using a loading device traceable to the National Institute of Standards and Technology (NIST). The transducer was accurate to within 1% in magnitude, 0.07 mm in medial/lateral location and 0.24 m in anterior/posterior location.

Calibration↗
PubMed1995

Metacarpophalangeal joint prostheses. A review of the clinical results of past and current designs.

The clinical results of past and current hinge, flexible and third generation designs of MP prosthetic joints are reviewed. The hinged prostheses did not achieve acceptable short term clinical results while the silastic and third generation prostheses provided good results with with correction of deformity and adequate range of motion (ROM). These good short term results did, however, get progressively worse with the recurrence of deformities and loss of ROM. It is evident that while most of the existing prostheses can relieve pain and restore appearance, none provide the degree of stability and ROM that is required to restore normal function to the MP joint. The moderate results could be partly due to the stage of the disease at which the surgery is carried out. At present, surgery on patients with rheumatoid arthritis is undertaken at a stage in the disease where the muscles and the ligaments surrounding the joint, and the bone, are generally in a poor condition. Surgery at this stage is really only a salvage procedure.

Arthritis, Rheumatoid↗
PubMed1988

Proposed digital arthroplasty critical study of the preliminary results.

In view of the results of Swanson implants, particularly the long-term course of silicone implants, the authors studied and developed semi-constrained sliding arthroplasty designed for metacarpo-phalangeal and proximal interphalangeal joints. The preliminary study on bones and then on cadaver hands and finally on the knee of the rabbit allowed the design and experimentation of a prototype which led to the creation of a semi-constrained arthroplasty for which the elastic diaphyseal anchoring is ensured without cement and which possesses sliding surfaces composed of a metallic (proximal piece)--polyethylene (distal piece) interface. We therefore describe the principles of functioning of this arthroplasty, its technique of insertion, dorsal trans-tendon incision, its accessory (drill for diaphyseal preparations), its anatomical requirements (preservation of the palmar plate and lateral ligaments, bone section) and the postoperative course. To date, 52 arthroplasties have been inserted and we present the results of the first 36 cases for which the follow-up is equal to or a greater than one year (20 MP-16 PIP), indicating the technical modalities according to the various aetiologies (21 cases of rheumatoid arthritis--15 post-traumatic cases) and the complications. The average gain in mobility is 40 degrees with a mean range of movement of 64 degrees. In terms of pain, none of the arthroplasties were associated with pain apart from pain on cold in certain post-traumatic cases. The global and thumb-finger prehensile forces were evaluated to be an average of 90% in relation to the healthy side. Radiological assessment demonstrated fixation of the pieces in every case. Lastly, we discuss the outcome of this arthroplasty and its current indications in relation to the problems of instability essentially occurring in dislocated MP joints of rheumatoid arthritis.

Arthritis, Rheumatoid↗
PubMedDate not supplied

[Improved osseointegration of titanium implants of different surface characteristics by the use of bone morphogenetic protein (BMP-3): an animal study performed at the metaphyseal bone bed in dogs].

AIM: Aim of this study was to determine whether coating of titanium implants of various surfaces with BMP-3 would improve the osseous integration of the implants into the orthotopic bony implant bed. METHOD: In this experimental study 190 micro g per implant of highly purified bone morphogenetic protein 3 (BMP-3) precipitate isolated from porcine bone were available for the coating of each of 24 cylindrical test implants (12 with hydroxyapatite and 12 with plasmapore surface). The remaining 24 test implants with the same surface makeup served as negative controls. Implantation sites were randomly assigned for the 4 versions of implants available and all implants were embedded into the medial or lateral femoral condyle of both legs of 12 German shepherds. The drilling holes were performed in such a matter that after embedding the cylindrical devices a gap of 1 mm surrounding the implants remained. A biomechanical testing and histological evaluation was performed on the explants 42 days after surgery. RESULTS: In biomechanical testing forces necessary to extract the implants from the explanted bones in BMP-3 coated devices were up to 70% higher compared to the ones in the non-coated reference groups. Quantitative histomorphometric examination showed in BMP-3-coated implants an increasing formation of new bone close to their own surface (gap-healing) which was higher than in the corresponding non-coated controls (hydroxyapatite + BMP-3 32.1%, hydroxyapatite controls 20.3%, plasmapore + BMP-3 30.2%, plasmapore controls 13.1%). The extent of direct bone implant contact as percentiles of the corresponding implants perimeter (ongrowth) was also significantly higher in the BMP-3-coated implants compared to the non-coated controls (hydroxyapatite + BMP-3 37.7%, hydroxyapatite controls 22.4%, plasmapore + BMP-3 15.3%, plasmapore controls 6.4%). CONCLUSION: In this study it was proven the first time that implants of various surface textures as used in endoprosthetics are able to be coated by the osteoinductive growth factor BMP-3. In that way metallic implants can achieve osteogenic properties which have positive effects in osseointegration.

Alloys↗
PubMed2001

Experimental and finite element comparison of various fixation designs in combined loads.

The short- and long-term successes of tibial cementless implants depend on the initial fixation stability often provided by posts and screws. In this work, a metallic plate was fixed to a polyurethane block with either two bone screws, two smooth-surfaced posts, or two novel smooth-surfaced posts with adjustable inclinations. For this last case, inclinations of 0, 1.5, and 3 deg were considered following insertion. A load of 1031 N was eccentrically applied on the plate at an angle of approximately 14 deg, which resulted in a 1000 N axial compressive force and a 250 N shear force. The response was measured under static and repetitive loading up to 4000 cycles at 1 Hz. The measured results demonstrate subsidence under load, lift-off on the unloaded side, and horizontal translation of the plate specially at the loaded side. Fatigue loading increased the displacements, primarily during the first 100 cycles. Comparison of various fixation systems indicated that the plate with screw fixation was the stiffest with the least subsidence and liftoff. The increase in post inclination from 0 to 3 deg stiffened the plate by diminishing the liftoff. All fixation systems demonstrated deterioration under repetitive loads. In general, the finite element predictions of the experimental fixation systems were in agreement with measurements. The finite element analyses showed that porous coated posts (modeled with nonlinear interface friction with and without coupling) generated slightly less resistance to liftoff than smooth-surfaced posts. In the presence of porous coated posts, Coulomb friction greatly overestimated the rigidity by reducing the liftoff and subsidence to levels even smaller than those predicted for the design with screw fixation. The sequence of combined load application also influenced the predicted response. Finally, the finite element model incorporating measured interface friction and pull-out responses can be used for the analysis of cementless total joint replacement systems during the post-operation period.

Biomechanical Phenomena↗
PubMed1998

Adaptive multimode lubrication in natural synovial joints and artificial joints.

To examine the lubrication mechanisms in both natural synovial joints and artificial joints with artificial cartilages, pendulum tests of pig shoulder joints and simulator tests of sliding pairs of a stainless steel spherical component and natural articular cartilage or artificial cartilage have been conducted. Firstly, it was shown in pendulum tests of pig shoulder joints that both concentration of hyaluronic acid or viscosity and adsorbed film formation of proteins and phospholipids exerted a significant effect on frictional behaviour in swinging motion immediately after a loading of 100 N. Under a high load of 1 kN, low friction was observed under wide-ranging viscosity conditions, since a high load similar to body weight probably enhanced the squeeze film effect due to improved congruity. Next, frictional behaviour of sliding pairs in knee joint models, consisting of a stainless steel spherical surface and either specimens of pig tibial cartilage or polyvinylalcohol (PVA) hydrogel, was examined during walking in simulator tests. In these tests, the influences of lubricant viscosity and addition of protein on frictional behaviour were evaluated. For both compliant materials, the appropriate addition of gamma-globulin to sodium hyaluronate (HA) solution maintained low friction and protected rubbing surfaces under thin film conditions. These phenomena are discussed from the viewpoint of adaptive multimode lubrication.

Animals↗