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At least 37 records · Page 2Linked to original sources
PubMed1979

Biomechanical evaluation of metacarpophalangeal joint prosthesis designs.

A laboratory biomechanical analysis of metacarpophalangeal joint prosthesis designs was done with fresh cadaver finger rays. The center of rotation, range of motion, tendon excursion, and fingertip force were determined on the specimens before and after implanting Swanson, Niebauer, Steffee II, St. Georg-Buchholz, Schultz, and modified Strickland prostheses. Their biomechanical behavior varied considerably and none duplicated the normal metacarpophalangeal (MP) joint. Each has design characteristics that may be clinically advantageous as well as disadvantageous. Irrespective of the design, the studies done cannot be divorced from the following factors: (1) implant material properties--silicone rubber implants buckled with tendon loading; this deformity created a significant flexor mechanical advantage and an extensor mechanical disadvantage; (2) implant fixation--freely movable implant stems dampened part of the applied load; braided suture provided inadequate immediate fixation; (3) implantation technique--the articulated prostheses can be technically unforgiving; errors in technique resulted in alteration of their biomechanical behavior.

Biomechanical Phenomena↗
PubMed2000

Design and wear testing of a temporomandibular joint prosthesis articulation.

As part of the development of a total temporomandibular joint prosthesis, a prosthesis articulation was designed. The articulation consists of a spherical head (ball) of the mandibular part, rotating against an enveloping ultra-high-molecular-weight polyethylene (UHMWPE) disc with a flat cranial side, which slides along the opposing skull part. The aim of this study was to determine the in vitro wear rate of the articulation, and to predict the in vivo wear rate from the results. Based on a disc thickness of 5 mm and a ball diameter of 8 mm, the stresses within the disc were calculated by means of a finite element computer model. The wear rate of the ball-disc articulation was determined by in vitro wear tests, with a stainless-steel ball rotating against a UHMWPE disc in a serum-based lubricant. Eight discs were tested for seven million cycles each. The in vitro wear rate of the disc-skull part articulation was calculated from the test results of the ball-disc articulation. The maximum Von Mises' stress was less than the yield strength of UHMWPE and, therefore, was sufficiently low. The in vitro wear rate of the ball-disc articulation was 0.47 mm3 per million cycles. The in vivo expected total wear rate is 0.65 mm3 per year, corresponding with a yearly decrease of disc thickness of 0.0094 mm. Although it is difficult to judge whether this wear rate is sufficiently low, because the influence of UHMWPE wear particles in the TMJ region is unknown, both the expected wear rate and the decrease of thickness appear to be acceptable.

Alloys↗
PubMed2006

[Semi-joint prosthesis replacement in treatment of malignant tumors around children's knees].

OBJECTIVE: To investigate the effect of the semi-joint prosthesis replacement in treating malignant tumors around the children's knees. METHODS: Five children (aged 8-12 years) with malignant tumors around the proximal end of the tibia underwent the semi-joint prostheses replacement from March 2000 to June 2005. All the children had been diagnosed with osteosarcoma, which was graded as II B by the Enneking staging system. The pathologic changes involved the upper segment of the tibia 9-11 cm in length. Before operation all the patients underwent puncture biopsy and standard chemotherapy. The lesion extent was determined by X-ray, CT and MRI, and then the size of the prosthesis was determined. The length of the prosthesis was 1-2 cm longer than that of the excised bone. After operation the patients were given neoadjuvant chemotherapy for 2 courses and they could walk with the help of a special brace 4 weeks postoperatively. RESULTS: All the 5 patients had a successful semi-joint prosthesis replacement except one patient who had a skin flap necrosis, and the wound healed after a flap grafting. The remaining patients had their wounds healed by first intention. The 12-36 months' follow-up revealed that all the patients had no metastasis or recurrence of the tumor and they were living and well except one patient who died of lung metastasis 8 months after operation. CONCLUSION: The semi-joint prosthesis replacement in the limb salvage surgery for malignant tumors around the children's knees has advantages of avoiding a damage to the normal osteoepiphysis, stabilizing the knee joint, and facilitating elongation of the limb in future. It also creates the condition for total knee replacement in adults.

Arthroplasty, Replacement, Knee↗
PubMed1975

Metacarpophalangeal joint implants. II. Roentgenographic study of the Niebauer--Cutter Metacarpophalangeal Joint Prosthesis.

A roentgenographic study was carried out on 41 Niebauer -- Cutter Metacarpophalangeal Joint Prosthesis from 1 to 36 months postoperatively, a total of 105 examinations. The examinations were performed in the AP-projection and in the lateral projection by tomography in maximum active extension and flexion. The tomographic examinations revealed implant damage of three kinds: cracking within the midsection; fragmentation of the midsection; fracture of the hinge. Cracking within the midsection was found in 8 implants between 6 and 12 months postoperatively and in 1 implant later than 12 months. Later examinations revealed fragmentation of the midsection in 2 implants previously showing cracks. Hinge fracture was observed in 22 implants. Implant damage was found in a total frequency of 26/41. Bone reaction was found on the tomograms in all the operated joints, and could not be evaluated on the AP-projections. A bony spur was found to develop on the metacarpal bone volarly at the site of the osteotomy in 35 joints. In 2 of these the bony spur reached the base of the proximal phalanx, causing anchylosis. Bone resorption was found in 23 joints, constantly dorsally in the metacarpal bone and volarly in the proximal phalanx. The mechanism of the implant damage is discussed with respect to the shearing forces in the joint and the two materials of differing elasticity constituting the implant. The bone reaction is discussed with respect to the intended fixation of the intramedullary stems.

Arthritis, Rheumatoid↗
PubMed1999

Wear-testing of a temporomandibular joint prosthesis: UHMWPE and PTFE against a metal ball, in water and in serum.

For a temporomandibular joint prosthesis, an estimation of the wear rate was needed, prior to patient application. Therefore, we determined the in vitro wear rate of the ball-socket articulation of this prosthesis, consisting of a metal head and an ultra-high molecular weight polyethylene (UHMWPE) cup. The basic testing configuration consisted of one 8-mm diameter stainless-steel ball, rotating between two conforming cups with a minimum thickness of 5 mm. For validation of the testing apparatus, two cup materials, in two lubricants, were tested. Both cup materials, UHMWPE and polytetrafluoroethylene (PTFE) were tested in deionized water, as well as in a serum-based solution. For UHMWPE in serum, eight samples were tested, for the other combinations four samples. For UHMWPE, the tests ran for 7 million cycles, for PTFE between 0.8 and 1.7 million cycles. For UHMWPE, the wear rate was 0.006 and 0.47 (mm3/10(6) cycles), in water and in serum, respectively. For PTFE, the wear rate was 2.8 and 47 (mm3/10(6) cycles), in water and in serum, respectively. For reason that testing in serum simulates the in vivo situation best, it was concluded that the wear rate of the TMJ prosthesis articulation is 0.47 (mm3/10(6) cycles), which is considered acceptable.

Biocompatible Materials↗
PubMed1975

Laboratory evaluation of a metal-plastic type of metacarpophalangeal joint prosthesis.

In the normal joint, the conformity of the joint surfaces can provide appreciable dorsal-volar shear stability when a compressive joint force acts. The centers of rotation were within 3 mm of the center of the metacarpal ball. Passive radial-ulna motion at 0 degrees flexion was close to 60 degrees, active motion being half of this; at 90 degrees flexion, there was 37 degrees passive and 23 degrees active motion. Studies of canal shapes and sizes showed that a transverse section deviated from circular by 1-2.5 mm; longitudinal sections were trumpet-shaped but had waves and ripples of about 0.5 mm. This is relevant to cement fixation. A metal-plastic prosthesis was tested in positions and with forces considered applicable to arthritics. It is possible that with plastic components, permanent deformation will progressively occur. The pull-out strength between cement and bone in cadaver bones was about 100 kg; metal stems in cement pulled out at about 50 kg, and plastic stems at 10-20 kg. Slippery stems pulled out at much lower values.

Evaluation Studies as Topic↗
PubMed2000

[Historical aspects of joint prosthesis implantation. A bibliographic study].

Joint replacements are frequent and effective. The results are generally very positive. It is important to understand former techniques and the historical development of artificial joints by reviewing the bibliographical sources. This article provides a thorough synopsis of former efforts to fully appreciate present-day successes.

Arthroplasty, Replacement↗
PubMed2000

Fitting a temporomandibular joint prosthesis to the skull.

Fitting a temporomandibular joint (TMJ) prosthesis to the skull by using stock prostheses seems to be an appropriate method. However, fitting the skull with one stock part requires many differently shaped parts. Therefore, we fitted the skull with two connected stock parts. The aim of the study was to test whether it is possible to achieve a close fit to the skull with this design, with a maximum of 10 different parts. The articular eminence was fitted with a gully-shaped fitting member, which was rotationally connected to a basic part that fitted to the lateral side of the TMJ. The relevant dimensions of 20 dry skulls were measured and the results were used to derive the optimal dimensions of the prosthesis parts. Prototypes were subsequently fabricated. The fit of the prototypes was tested by measuring the maximum gap between fitting member and skull. All skulls could be fit with a set of four different basic parts and three different fitting members. The average maximum gap between fitting member and skull was 0.20 mm (range 0.11-0.43 mm). It was concluded that a close fit to the skull can be achieved with two connected stock parts and with a total number of seven parts.

Feasibility Studies↗
PubMed1990

The APS knee joint prosthesis. A review of 32 patients.

First clinical and radiographic results with a new knee joint prosthesis, implanted without cement, are reported and the characteristics of the implant (dowel fixation and special instrumentation) presented. The first series of 35 joints with a follow-up period of 1-3 years shows excellent results. Radiographically, primary osseous integration cannot be positively identified in all cases, but it could be proved in most instances. Cement-free implantation requires good preoperative bone quality and an operative technique which inserts the implant anatomically. If these two conditions are met, there is every probability of successful implantation. No problems specific to the implant have been encountered.

Adult↗
PubMed1984

[Experimental studies on polyacetal composites for joint prosthesis].

UNLABELLED: Composite polymer resin is one of the most promising materials for its excellent bio-functions. The purpose of the present studies is to prove the applicability of polyacetal composites as a biomaterial for joint prostheses from in vivo as well as in vitro experiments. MATERIALS AND METHODS: The polymeric materials tested in the studies were acetal copolymer resin (POM) reinforced with 20% carbon fiber (CR20), POM with 10% fluorine powder (YF 10), POM alone, ultra high molecular weight polyethylene (UHMWPE) and UHMWPE reinforced with 10% carbon fiber (Poly two). Experiment I: Evaluation of biocompatibility in vivo by injecting polymeric powders into the abdominal cavity of mice, and in vitro with a tissue culture method. Experiment II: Friction and wear tests with a slider and a plate under different lubricants, the slider was made of stainless steel or ceramic. Coefficient of friction and specific wear rate were measured, and the wear surface was observed with scanning electron microscope (SEM). Müller type acetabular cups used for the simulation test were made of reinforced POMs, UHMWPE, and Poly two. A walk simulator was made to test the tribological behavior of hip joint prostheses in which the frictional counterpart was made of ceramic. Roughness of the wear surface, and ultimate frictional torque were measured and the surface microstructure was observed with SEM. Experiment III: Application for joint replacement. As a first step, screwshaped test pieces were inserted into the proximal end of the tibia of Beagle dogs, and ultimate rotating torque was measured to investigate the degree of fixation of reinforced POMs to the bone. A hip joint prosthesis of self-locking and cementless type was made and implanted in 12 dogs. Nine dogs were sacrificed more than 24 weeks after the implantation and investigated radiographically and histopathologically. RESULTS AND CONCLUSIONS: Reinforced POMs showed similar biocompatibility as other biomaterials for joint prostheses. In the combination with ceramic, the coefficient of CR20 tends to decrease with the increase of load and prolapsed time. SEM findings showed low specific wear. After the simulation test, the surface of CR20 cup became smoother. Poly two showed almost the same frictional torque as CR20, but its reinforced carbon fibers seem to be easily drifted away from the wear surface. The CR20 test pieces showed as firm fixation to the bone as those of stainless steel. The implantation tests were excellent in 2 and good in 3 dogs at the point of fixation of the socket with the bone out of 9 dogs tested.(ABSTRACT TRUNCATED AT 400 WORDS)

Acetals↗
PubMed1977

[On the stress state of bone cement fixing a hip joint prosthesis (author's transl)].

Using a simplified model, tests were made to investigate the shear stress distribution at a hip joint prosthesis. A marked increase of stress at the tip of the prosthesis was found through photoelasticity. This peak stress resulted in a safety factor of 3 against exceeding the shear strength of bone cement. Since the calculation of the stress is based on unfavourable assumptions, the actual factor of safety should show a higher value still.

Bone Cements↗
PubMed1983

Release of cobalt and nickel from a new total finger joint prosthesis made of vitallium.

An in vivo study of a new total finger joint prosthesis was performed to evaluate a biological ingrowth system of attachment of the device to bone. The prosthesis consisted of two conical ribbed ultrahigh molecular weight polyethylene plugs that were fixed by impaction into the medullary cavity after reaming. A cobalt--chromium alloy metal stemmed hinge slides inside the plugs with the joint articulation at the end of the stem. The focus of this study was to measure the concentration of cobalt and nickel in the serum, erythrocytes, and periarticular tissue (muscle from the sartorius and vastus medialis) resulting from the implantation of this device in the knee of the cat for periods of up to 1 year. The results indicate significant elevation in serum cobalt concentrations only after 5 months and increased concentrations in serum nickel which, were more pronounced after two months. Column chromatographic separations on cross-linked Dextran (G-200) shows a different distribution across the three principal protein peaks for each metal.

Animals↗
PubMed2000

Silicone lymphadenopathy mimicking a lymphoma in a patient with a metatarsophalangeal joint prosthesis.

With lymph node enlargement, the possibility of a malignant process such as metastatic carcinoma or lymphoma needs to be excluded. This report describes a 47 year old woman with inguinal lymph node enlargement initially suspicious for lymphoma. Fine needle aspiration findings favoured reactive hyperplasia, but a malignant process could not be excluded. The final histological diagnosis was a foreign body granulomatous inflammatory response as a result of regionally disseminated silicone particles from an over looked metatarsophalangeal joint prosthesis. Because of the large number of joint prostheses world wide, it should be kept in mind that migration of wear particles can create granulomatous inflammation and node enlargement.

Diagnosis, Differential↗
PubMed1982

[The Anatomical sliding-axis knee-joint prosthesis (author's transl)].

In order to avoid the disadvantages of a fixed axis the newly-designed knee-joint prosthesis was equipped with a sliding one. This is not a load-bearing component; its main purpose is to guide the movement of the endoprosthesis. The design permits almost physiological movement, thus diminishing the detrimental forces at the anchor points. To further improve anchoring the shafts of the prosthesis were designed with an anatomical cross-section. The design of the anatomical sliding-axis prosthesis is described and the results of the first 36 implantations are presented.

Biomechanical Phenomena↗
PubMed2001

Cobalt-specific T lymphocytes in synovial tissue after an allergic reaction to a cobalt alloy joint prosthesis.

Metals such as cobalt and nickel are common contact allergens. We studied the mechanisms underlying an allergic reaction with marked synovial inflammation in a patient with a cobalt alloy arthroplasty. After removing the joint prosthesis the adjacent synovial tissue was examined for cobalt-specific T lymphocytes. Synovial membrane mononuclear cells were expanded in interleukin 2 and cloned using a representative cloning protocol. T cell clones were tested for their proliferative response to cobalt and further characterized with regard to cytokine secretion, phenotype, and HLA restriction. Additionally, synovial fibroblasts were tested for their function as antigen presenting cells (APC). Almost 30% of the T cell clones reacted to cobalt, but not to the control nickel. All these T cell clones were CD4 positive. The cobalt induced proliferative response could be blocked by anticlass II antibodies. Also, synovial fibroblasts expressing class II molecules induced by interferon-gamma were able to serve as APC. However, when testing a panel of APC of HLA class II mismatched donors, no requirement for a certain HLA class II molecule could be defined. Further studies are necessary to determine mechanisms of presentation and recognition of cobalt by T lymphocytes, a prerequisite for improved prevention and treatment of metal induced allergic reactions.

Antigen Presentation↗