In vitro stability of the implanted total condylar prosthesis. Effects of joint load and of sectioning the posterior cruciate ligament.
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[Dependable pace-accommodating knee joint for thigh prosthesis].
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Extremities↗
[General principles of infection treatment in joint replacements].
The treatment of infection in joint replacements, which is a complex issue, is justly considered to be one of the most expensive orthopedic procedures. The choice of treatment is determined by a number of criteria that are based on exact patients' history and their clinical, imaging and laboratory data. The management of infection reflects the development in the field of arthroplasty. In the past, the therapy was rather simple, involving removal of the implant, eradication of the infection and simple anatomical intervention in order to make the extremity useful for the patient, often at the cost of many concessions. At present, with rapid advancements of alloplasty, patients' requirements for joint motion are increasing and the ultimate goal is a new and fully functioning joint prosthesis. This treatment is based on early diagnosis as well as early surgical intervention. Antibiotic therapy alone is indicated only in Coventry's type I infection, when positive results of bacterial cultivation are known only after the surgical procedure. A 6-week antibiotic course is administered according to the sensitivity of the isolated bacterial strain. Although treatment solely with antibiotics is preferred by the patients, its long-term outcomes, with the exception of the indication mentioned above, are completely ineffective. Surgical inspection and lavage without implant removal and a subsequent antibiotic course are indicated in type II infection. The procedure involves thorough debridement and replacement of the articulating component, followed by conventional lavage irrigation. One-stage reimplantation requires implant removal, debridement and insertion of a new implant. This is indicated in patients with type III and type IV alloplasty infection by Gram-positive sensitive bacteria that do not produce a glycocalyx layer and in patients in whom the bone bed is without major defects. The method of choice is an implant fixed with antibiotic- loaded cement.One-stage reimplantation is associated with a shorter absence from work, lower costs and better comfort for the patient. Two-stage reimplantation is generally preferred. It is indicated in type III and type IV alloplasty infections caused by resistant or polymicrobial flora or by glycocalyx-producing bacteria, and in patients with large defects of the bone bed. The first stage includes removal of all prosthetic components, thorough debridement and insertion of a cement, conventional or articulating, spacer. Lavage irrigation follows. Based on clinical and laboratory findings, the second stage procedure is carried out after 6 to 12 weeks and a new, usually cementless implant is inserted and defects are repaired, if present. In the treatment of infected alloplasty, a cement spacer has two roles; it provides stability for the joint region after removal of the replacement and, by releasing antibiotics, it prevents the spacer from colonization by bacteria. The cement spacer can be prepared in several ways. The modification preferred by the authors consists only of antibiotic-loaded bone cement moulded in such a way that it can fulfill its stabilizing function and, in hip joints, partially also its locomotor function. Other options include a commercially-produced cement spacer, which has the shape of a cervicocapital prosthesis and is merely placed in the bone bed, or the PROSTALAC system. A three-stage reimplantation procedure is suitable for treatment of extensive bone defects in which the use of a large amount of morselized homograft can be anticipated. The bone bed created from homografts is allowed to incorporate for about 6 months and, in most cases, a cementless implant is subsequently inserted.
Anti-Bacterial Agents↗
Human articular cartilage during osteoarthrosis: a study under the scanning electron microscope.
The present study has been carried out with the aim of contributing, by means of the Scanning Electron Microscope (SEM), to the understanding of morphological changes in human articular cartilage during osteoarthrosis. Fragments from the femoral head of 10 patients subjected to total hip joint prosthesis were cryofractured and then studied by SEM after treatment with current procedures. The images obtained were considered observing the division of cartilage into superficial, medium and deep layers. The superficial layer is the one which suffers most seriously during osteoarthrosis, but collagen alterations, as fibrillation, involve all the layers together. Moreover, the observation of deformed cellular lacunae in the deep layer suggests that a precocious functional collapse involves the whole thickness of the cartilage, probably due to a metabolic suffering.
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Reinforcement of bone cement using metal meshes.
Following on from previous work reported in this journal, a practical system has been developed for in situ fibre reinforcement of bone cement in the hip joint prosthesis. A fibre preform is inserted during the operation, surrounding the metal stem of the prosthesis, forming a composite with the cement. Tests performed on full-scale models of the joint show improvements in fatigue life by more than an order of magnitude when a preform of metal fibres is used; this significantly delays the onset of cement cracking and stem loosening. Initial results reported previously suggest that other fibre materials such as carbon may give even greater improvements. Clinical trials have begun, using a form of the metal mesh.
Bone Cements↗
Localised mastocytosis at the bone and porous coated interface of a knee prosthesis.
A porous coated tibial plateau component, which was not loose, was removed 6 weeks after operation. An absence of bony ingrowth was demonstrated by histological and microradiographic examination. The radiolucent space was filled by young connective tissue and inflammation was indicated by the presence of a few macrophages or foreign body giant cells; there was also an increased number of mast cells near the metallic beads. Such inflammatory cells have not previously been reported around a firmly fixed joint prosthesis, but they have been associated with metallic particles. Since accumulations of mast cells can interfere with the process of bony ingrowth, further studies of removed porous coated prostheses should be made with adequate histological techniques so that the clinical significance of these cells can be better understood.
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Investigation of joint disease.
The role of nuclear medicine in the diagnosis and management of the major arthropathies is critically reviewed, with particular reference to osteoarthritis, rheumatoid and similar forms of arthritis, ankylosing spondylitis, non-specific back pain, gout, the neuropathic joint, avascular necrosis, infection and the consequences of prosthetic joint insertion. Attention is drawn both to practical applications and deficiencies in current techniques and knowledge.
Adult↗
A two year in vivo study of polyvinyl alcohol-hydrogel (PVA-H) artificial meniscus.
For the recognized importance of knee meniscus function, the treatment of meniscus injury has been changing from resection to repair. However, depending on the type of injury, meniscectomy sometimes cannot be avoided. In such a case, it is important to anticipate the future problem of degenerative change or osteoarthrosis in the knee joint. In consideration of the prognosis and circumstances in such patients, we have developed an artificial meniscus using polyvinyl alcohol-hydrogel (PVA-H) for salvage. We have already reported the results up to 1 year after animal operation. The present study investigated the results in postoperative 2.0 years to assess further the use of artificial meniscus. In the results, the articular cartilage state of knee joint implanted PVA-H meniscus was good even after 2 years, while Osteoarthrosis (OA) change progressed in meniscectomy knee joint. In addition, neither wear, dislocation nor breakage of PVA-H was observed. These results proved that an artificial meniscus using PVA-H can compensate for meniscal function and might be clinically applicable.
Animals↗
Objective clinical evaluation of function. Gait analysis.
Automated gait analysis allows us to document and quantify objectively normal gait, functional deficits, and patient response to therapeutic intervention. Instrumentation for this analysis at the Mayo Clinic Gait Laboratory includes three-dimensional electrogoniometers for measurement of relative joint rotation at the hip, knee, and ankle; footswitches that record foot-floor contact sequences; instrumented mats that measure step length and width; piezoelectric force plates for measurement of floor reaction forces; and two walkways that simulate a variety of ground conditions. We use a DEC-PDP 11/34 computer for acquisition, storage, and analysis of data and for generation of a gait report form that displays a patient's results relative to normal and previous evaluations. Applications of these techniques include assessment of function preoperative and postoperative total joint arthroplasty, quantification of gait faults, and documentation of effectiveness of exercise and gait training techniques. We have demonstrated the reliability of the techniques, accumulated a sizeable normal data bank, and developed a concise, effective data summary for communication with referring practitioners.
Amputees↗
Medical devices; classification of temporomandibular joint implants--FDA. Final rule.
The Food and Drug Administration (FDA) is classifying four temporomandibular joint (TMJ) implants, the total temporomandibular joint prosthesis, the glenoid fossa prosthesis, the mandibular condyle prosthesis, and the interarticular disc prosthesis (interpositional implant), into class III (premarket approval). These actions are being taken under the Federal Food, Drug, and Cosmetic Act (the act), as amended by the Medical Device Amendments of 1976 (the 1976 amendments) and the Safe Medical Devices Act of 1990 (the SMDA).
Dental Prosthesis↗
Surgery of the lower limb in rheumatoid arthritis.
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Arthritis, Rheumatoid↗
[Biomechanics of natural and artificial joints].
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Animals↗
[Homografts allogeneic of the knee and hip joints].
The technique and instruments of PAP, Krompecher and Jaros allow a precise preparation of the femoral head, acetabulum, femoral condyles and tibial plateau in the donor and recipient for the application of homograft transplants of joint articular surfaces of 5 millimetre thickness. In the present series, specimens were preserved by freezing at 30 degrees below zero to prevent immunologic reactions in the recipient. Immunogenic control tests in 12 patients have shown that freezing at 30 degrees below zero does not eliminate antigens in the transplant. In future, therefore, it is intended to transplant only cartilage with living cells in relation to the HLA system. The problem of prevention of infection has been solved by a special antibiotic preparation of the specimen. Radiographic examination 4 years after operation shows that only two of 12 patients had an unsatisfactory result. Function in these two hip joints is, however, better than before operation although the transplant has been partly resorbed. The technique of homograft transplantation of the hip and knee joints is suitable for young or middle-aged individuals in whom the only alternative would be an arthrodesis. For older persons a joint prosthesis is preferable.
Adult↗
A metallic hemiarthroplasty resurfacing prosthesis for the hallux metatarsophalangeal joint.
Two-hundred seventy-nine arthritic hallux metatarsophalangeal joints treated surgically with a metallic resurfacing hemiarthroplasty over a 40-year period were reviewed. The implant, which is made available in three evenly graded sizes, is designed to replace only the articular surface of the proximal phalanx, with minimal resection of bone stock. The pathologic indications for surgery included classical hallux rigidus, rheumatoid arthritis, and degenerative changes associated with hallux valgus and bunion deformity. Follow-up at 8 months to 33 years after surgery revealed good or excellent clinical results in 95%. The time to follow-up was in excess of 5 years in 101 (36%) of the procedures, beyond 10 years in 62 (22%), and longer than 20 years in 23 (8%). Unlike other available surgical options for this debilitating condition, biomechanics of the hallux metatarsophalangeal joint remained unaffected and problems associated with prosthetic wear or mechanical failure were not encountered.
Adult↗
Antibiotic prophylaxis for dental or urological procedures following hip or knee replacement.
OBJECTIVES: Reports of prosthetic joint infection associated with urological or dental procedures have prompted suggestions that these patients require antibiotic prophylaxis, but no guidelines have been agreed. We have polled orthopaedic surgeons, urologists, and dentists on this issue. METHODS: The questions asked were: could infection of a joint prosthesis result from a dental or urological procedure; does the risk of infection warrant patients informing their dentist or urologist about their joint replacement; should these patients have prophylactic antibiotics for (a) routine procedures and (b) lengthy procedures. RESULTS: Urologists and orthopaedic surgeons agreed that infection could probably result from urological procedures and that patients should definitely inform their urologist about their prosthesis. Orthopaedic surgeons thought that antibiotics were definitely indicated for routine and lengthy urological procedures while urologists thought antibiotics were probably indicated. Orthopaedic surgeons thought that infection probably could result from dental procedures, while dentists answered "don't know". Both groups agreed that patients should definitely inform their dentist about their prosthesis. Orthopaedic surgeons thought that antibiotics probably were necessary for routine and lengthy dental procedures, whereas dentists answered "probably not" and "don't know", respectively. CONCLUSIONS: These results could provide the basis for a consensus regarding prophylactic antibiotic use in this growing patient population.
Anti-Bacterial Agents↗
[Spatial kinematics of the femoro-tibial articulation of the human knee: experimental characterization and surgical implication].
The entire flexion of the human knee joint was experimentally studied by means of spatial solid kinematic theory. This study used postmortem joints, initially intact, then with the menisci removed, and finally without the antero-external cruciate ligament. The instantaneous velocities were defined in kinematic theory; then they were transformed into incremental displacements of the tibia which was considered as a moving solid relative to the femur, which was considered as the reference solid. The rotational movement of tibia was computed as being the main degree of freedom; then it was divided into three physiological components: flexion-extension, axial rotation, and varus-valgus rotation. The computation of the instant axis of the motion allowed definition of an area that was characterized as a central zone of the joint motion. This 3-dimensional approach was in opposition to the classical but incorrect definitions of the instant center of rotation, which can be described only for movement within a plane. Eight anatomical knee joints were tested and their mean results were used to elucidate conceptual problems relative to the femoro-tibial knee-joint prosthesis design.
Anterior Cruciate Ligament↗
[Testing the usefulness of a provisional polyester prosthesis for augmentation in reconstructive operations of knee joint ligaments].
Prosthesis from polyester fibres 5 mm wide with loose knitting finished on both ends with teflon handles for fixing bones with a wholly aphid screw made by Tricomed company in Lódź according to its own idea was the subject of the test. The tests were made on 7 piglets. The prosthesis together with an autogenic graft taken from the middle third of a patella ligaments was implanted into the place of the excised front sacral ligament. The implanted prosthesis was characterised with a high biocompatibility, satisfying mechanical resistance and easiness of fixing of the tested graft. We noticed clinically and pertaining to autopsy the possibility of removing the allogenic graft after achieving the full healing of the autogenic graft without the possibility of hurting that last one.
Animals↗