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At least 19 recordsLinked to original sources
PubMed1992

Measurement of the heat of reaction transmitted intracranially during polymerization of methylmethacrylate cranial bone cement used in stabilization of the fossa component of an alloplastic temporomandibular joint prosthesis.

Temporomandibular joint alloplastic fossa replacements have always been difficult to stabilize because of the variability of the anatomy in the area both in normal and especially in pathologic states. Total joint reconstruction and stabilization in orthopedic surgery have been aided by the use of methylmethacrylate, which is used both as a cementing substance and as a filler material when there are voids between the implant and the basilar bone. The concept of the use of a filler material to aid in the stabilization of the alloplastic temporomandibular joint fossa is attractive, but of concern because of the exothermic reaction this material undergoes as it sets in proximity to the middle cranial fossa. This study was designed to measure the temperature gradient that exists in such a procedure when used with cadaver specimens. The results indicate that the heat of reaction was not significantly transmitted intracranially in the cadavers studied. However, I recommend care in the use of this material for this purpose with patients.

Bone Cements↗
PubMed2000

[Experiences with the alloplastic joint prosthesis of the interphalangeal joint].

The replacement of finger joints, especially of the proximal interphalangeal joint (PIP), remains an unsolved problem. Long-term results of conventional reconstructive procedures as well as previously available artificial joint implants have been disappointing. In a controlled study, 12 PIP-joints were replaced by a new type of total endoprosthesis as an alternative to joint fusion. The cementless prosthesis is unhinged and consists of metal joint surfaces. After a follow-up of 18 months, implantation of this metal prosthesis resulted in almost complete pain relief and an active range of movement of 58 degrees. The absolute gain in mobility, however, was only 6 degrees. A swan-neck deformity was found in nine out of 12 cases but corrective surgery was not required. The proximal half of the implant had to be exchanged in two cases due to loosening. All patients were satisfied with the result. The disparity between subjective acceptance by the patients, who clearly prefer joint replacement to fusion, and objective results demonstrates the necessity for further development in this field. The type of prosthesis used in this study seems to be a useful baseline tool which could be turned into a ingenious PIP-joint replacement by further development aiming at reduced abrasion, increased initial stability, a more individual configuration, to name just a few goals.

Equipment Failure Analysis↗
PubMedDate not supplied

A new finger joint prosthesis.

A new finger joint prosthesis is being developed for the proximal and distal interphalangeal positions. Currently available "joint spacer" prostheses provide relief from pain and cosmetic improvement, but relatively poor long-term function. The new prosthesis employs a mechanical hinge at the joint. It is fabricated from titanium alloy (6A14V). The hinge mechanism avoids direct metal to metal contact by using high density polyethylene bearings. In vitro tests of the hinge mechanism have passed 75 million cycles of continuous flexure without failure (n = 12). The hinge also incorporates a mechanical limit stop to prevent hyperextension. The hinge mechanism is enclosed in a sealed elastomeric jacket that isolates the hinge from connective tissue ingrowth. The jacket, equivalent to an artificial synovial membrane, has an integrally textured exterior surface designed to promote tissue attachment to the implant to stabilize tissue capsule formation around the joint. To test the in vivo efficacy of the new design, a series of 12 devices were implanted in the knee joint position of adult rabbits. A jacketed prosthesis was implanted on one side, whereas 2 weeks later an unjacketed control was implanted contralaterally. The animals then were maintained for an 8 week period. At sacrifice, the implants were removed, and the response of the surrounding tissues was studied histologically. At the time of implantation, the range of motion of the joints was approximately 100-105 degrees. There was a progressive loss in range of motion observed in both groups. The fibrous tissue capsule around the jacketed implants, however, was significantly reduced in thickness compared with the controls (mean thickness, 1.5 mm vs. 4.5 mm).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1996

Cellular basis for failure of joint prosthesis.

In recent times, loosening of joint prosthesis resulting in failure, is of grave concern to orthopedicians. It is estimated that 50% of total hip replacements become loose after 15 years, and most of them require either revision surgery or resection orthoplasty. Neither, newer operative techniques, change in design, use of novel materials, nor surface modifications have helped to circumvent the problem. It is in this context, that attention has been focussed on the role of tissue surrounding the implant, in the loosening of the prosthesis. Tissue response around prosthesis results in either formation of a fibrous layer around the implant, ingrowth into fenestrations on implant or direct bone apposition on prosthesis. Long-term implantation results in implant debris being released into surrounding tissue. These particles initiate a chronic granulonatous inflammation with a significant number of activated macrophages and foreign body type of giant cells, all engaged in attempts to get rid of the debris. These features have been found to be invariably associated with peri-prosthetic lysis of bone. Since such bone resorption is also observed around non-cemented prosthesis, possibly causes other than cement are responsible for the osteolysis. Retrospective studies on failed implants suggest that peri-prosthetic osteolysis is mediated by activated macrophages. Cytokines are capable of stimulating bone resorbing cells, the osteoclasts. Bone resorption results in further loosening of the prosthesis, changes in stress, frictional wear, release of more wear debris and recruitment of more macrophages. Bone death and proliferation of macrophages, thus appear to be the cause for pain and loosening of prosthesis.

Biocompatible Materials↗
PubMed1976

[Knee joint prosthesis with the geomedic knee joint (author's transl)].

Thirty-one cases of plastic knee joint operations were reported. Twenty-one patients were treated with the geomedic knee. The advantage of this joint is that only a small amount of bone must be sacraficed. The range of movement is better than that with a complete knee prosthesis with axis.

Aged↗
PubMed1999

Ossiculoplasty in young children with the Applebaum incudostapedial joint prosthesis.

OBJECTIVE: To evaluate the performance of the Applebaum incudostapedial joint prosthesis in young children in terms of hearing results and long-term stability despite continuing eustachian tube dysfunction and otitis media. STUDY DESIGN: Retrospective review of all Applebaum prostheses placed in children at our institution from June 1993 to June 1998. RESULTS: In 1993 Applebaum proposed the use of a hydroxylapatite ossicular prosthesis as an alternative to incus interposition for the repair of incudostapedial discontinuity. We have used this prosthesis exclusively for the repair of such defects in children over the past 5 years. Among 12 operated ears, all healed, all prostheses remain in place (average duration, 2.6 y), and all children have excellent hearing (mean air-bone gap, 15 dB; range, 5-25 dB). CONCLUSIONS: The Applebaum incudostapedial joint prosthesis restores conductive hearing even in young children. It has been stable in the face of recurrent otitis media and has not interfered with revision surgery. Placement of the prosthesis at primary cholesteatoma surgery should be considered in children.

Adolescent↗
PubMed1993

Parametric modelling of a knee joint prosthesis.

This paper presents an approach for the establishment of a parametric model of knee joint prosthesis. Four different sizes of a commercial prosthesis are used as an example in the study. A reverse engineering technique was employed to reconstruct the prosthesis on CATIA, a CAD (computer aided design) system. Parametric models were established as a result of the analysis. Using the parametric model established and the knee data obtained from a clinical study on 21 pairs of cadaveric Asian knees, the development of a prototype prosthesis that suits a patient with a very small knee joint is presented. However, it was found that modification to certain parameters may be inevitable due to the uniqueness of the Asian knee. An avenue for rapid modelling and eventually economical production of a customized knee joint prosthesis for patients is proposed and discussed.

Asian People↗
PubMed2003

TMJ Concepts/Techmedica custom-made TMJ total joint prosthesis: 5-year follow-up study.

This prospective study evaluated the 5 to 8 year subjective and objective results of 42 consecutive patients who had TMJ reconstruction using the TMJ Concepts/Techmedica custom made total joint prosthesis. Criteria for use of the prosthesis included the following TMJ conditions: (1) multiply operated, (2) previous alloplastic implants, (3) osteoarthritis, (4) inflammatory or resorptive arthritis, (5) connective tissue or autoimmune disease, (6) ankylosis, and (7) absent or deformed structures. Thirty-eight of 42 patients (90%) with 69 TMJs reconstructed using the TMJ Concepts/Techmedica total joint prosthesis had appropriate data for inclusion in the study. The average age at surgery was 36 years and average follow-up was 73.5 months. The entire group and three subgroups were objectively evaluated for incisal opening, lateral excursions, and occlusal stability, while subjectively assessed for pain and jaw function. Paired t-test and comparison analyses were used to assess outcomes. For the group of 38 patients, there was statistically significant improvement in incisal opening (P=0.001), jaw function (P=0.001), and pain level (P=0.0001). Lateral excursion movements significantly decreased (P=0.04). The occlusion remained stable in all cases. Complications occurred in six patients. Comparison analysis of the three groups demonstrated significantly better outcomes for patients with fewer previous TMJ surgeries and without exposure to Proplast-Teflon or Silastic TMJ implants. This study demonstrated that the TMJ Concepts/Techmedica total joint prosthesis is a viable technique for TMJ reconstruction as a primary procedure and for patients with previous multiple TMJ surgeries and mutilated anatomy of the TMJ.

Adolescent↗
PubMedDate not supplied

Image technique optimization in MR imaging of a titanium alloy joint prosthesis.

The purpose of this study was to explore systematically the effect of the imaging parameters changeable by the user in spin-echo (SE) imaging sequences to minimize image distortion when imaging joint prostheses. A titanium alloy hip joint prosthesis was studied at I.O.T. The SE imaging parameters were bandwidth/pixel(BW/ p), TE, strength of encoding gradients (matrix size), echo train length (ETL), and direction of phase and frequency encoding. The effect of ETL in rapid acquisition relaxation enhanced (RARE) sequences was also evaluated with a turbo-SE sequence using a different ETL with the same TR and an effective TE. It is concluded that an optimized image quality can be achieved in SE imaging by using a high bandwidth/pixel value (at least 130 Hz/pixel), a high resolution matrix (256-512), sequences with multiple refocusing, and a frequency-encoding axis parallel to the long axis of the prosthesis. The degree of distortion is reduced with this optimized technique.

Alloys↗