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PubMed1993

Ceramic formation on metallic surfaces (ceramization) for medical applications.

Surface transformations can be performed on metals in order to combine their load-bearing properties to the inertness and wear resistance of ceramics. In a joint prosthesis, metals are useful for their high fatigue strength and ductility, but they are more sensitive to superficial corrosion and wear than ceramics. Coating a ceramic on metal surface will improve the qualities of the metallic component. The various ways of transforming a metallic surface into a ceramic one are described. First, the surface treatments to improve the friction and wear properties are analysed. Coatings and surface transformations give superficial inert compounds. Many techniques are used to create hard, corrosion resistant layers on the surface. The processes may involve heating of the treated parts. But some metals cannot be heated without an alteration of their mechanical properties. The adhesion strength--and thus, the lifetime--of the ceramic layers depend on the binding forces and on the structure of the interfaces between the bulk metal and the outermost ceramic. Coatings generally have a lower adhesion strength than in-situ formed phases and the risk of peeling is higher. Second, the plasma-sprayed coatings performed to improve the bone anchorage are described. This review does not deal with bioactive materials. So, only the alumina coatings and their mechanical compatibility advantage are present.

Adhesiveness↗
PubMedDate not supplied

Disc arthroplasty: lessons learned from total joint arthroplasty.

BACKGROUND CONTEXT: With the rapid emergence of new disc arthroplasty designs and ongoing clinical trials, there is great anticipation among clinicians. Inevitably there will be challenges associated with adoption of this new technology. Potential lessons learned from the extensive experience with extremity arthroplasty may predict some of the perils and pitfalls associated with motion-preserving devices in spinal applications. PURPOSE: To review the extremity total joint literature for lessons that may be transferable to disc arthroplasty and anticipate predictable problems that will occur. STUDY DESIGN/SETTING: A literature review and conjectural analysis of key lessons learned from the experience of extremity total joint arthroplasty and anterior lumbar interbody fusion devices with subsequent application of these lessons to disc arthroplasty in the lumbar spine. METHODS: Limited data are available on disc arthroplasty. RESULTS: Particular areas of controversy and uncertainty exist. The ongoing US Food and Drug Administration Investigational Device Exemption clinical trials may provide additional insight into these questions. CONCLUSIONS: Complications will occur. These will be approach related, device related and patient-selection related. Studying the experience of extremity joint arthroplasty may accelerate the learning curve for lumbar disc arthroplasty.

Arthroplasty, Replacement↗
PubMedDate not supplied

Osteomyelitis.

Bone and joint infections are painful for patients and frustrating for both them and their doctors. The high success rates of antimicrobial therapy in most infectious diseases have not yet been achieved in bone and joint infections owing to the physiological and anatomical characteristics of bone. The key to successful management is early diagnosis, including bone sampling for microbiological and pathological examination to allow targeted and long-lasting antimicrobial therapy. The various types of osteomyelitis require differing medical and surgical therapeutic strategies. These types include, in order of decreasing frequency: osteomyelitis secondary to a contiguous focus of infection (after trauma, surgery, or insertion of a joint prosthesis); that secondary to vascular insufficiency (in diabetic foot infections); or that of haematogenous origin. Chronic osteomyelitis is associated with avascular necrosis of bone and formation of sequestrum (dead bone), and surgical debridement is necessary for cure in addition to antibiotic therapy. By contrast, acute osteomyelitis can respond to antibiotics alone. Generally, a multidisciplinary approach is required for success, involving expertise in orthopaedic surgery, infectious diseases, and plastic surgery, as well as vascular surgery, particularly for complex cases with soft-tissue loss.

Humans↗
PubMed1997

Surgical treatment of osteoarthritis.

Surgical treatment of OA is appropriate when conservative therapy fails or is inadequate. The veterinary orthopedist's goals in treatment should be to alleviate pain, maintain function, and prevent or remove the potential for further degeneration of the joint. Currently, in veterinary surgery, THR and femoral head and neck excision are the primary treatments for OA of the coxofemoral joint. Other joints are treated primarily by arthrodesis or excision arthroplasty. Arthroscopy is proving to be a valuable tool in the diagnosis and treatment of OA, and total stifle and elbow replacement and cartilage resurfacing through chondrocyte grafting are on the horizon as potential treatment options.

Animals↗
PubMed2001

[Hyperparathyroidism induced by lithium. A new case].

INTRODUCTION: Lithium salts, used for the first time in 1949, had proved to be a highly effective preventive measure in bipolar illness. The first report of lithium-induced hyperparathyroidism was suggested by Garfinkel et al. in 1973. About 40 cases have been reported since, suggesting an enhancement of occurrence of hyperparathyroidism in patients cured by lithium carbonate. We report here a new case discovered by a systematic measurement of calcemia after a surgical intervention for a hip joint prosthesis. EXEGESIS: Unusual metabolic features associated with this case of hyperparathyroidism include low urinary calcium excretion, normal cyclic AMP excretion and lack of calcic nephrolithiasis. The mechanism probably results from lithium linking with the calcium receptor on the parathyroid and then stimulating PTH secretion. In the same way it could enhance the tubular reabsorption of urinary calcium. Lithium withdrawal is often inefficient in clinical and laboratory test abnormalities and surgery is usually required. CONCLUSION: It is very important to recognise this particular secondary effect of lithium therapy because clinical symptoms of hypercalcemia can simulate a worsening of the bipolar illness.

Adult↗
PubMed1991

Histological patterns of bone and articular tissues after orthopaedic reconstructive surgery (artificial joint implants).

Revision surgery after failures of joint replacements leads to histological studies on joint and bone tissues close to the implanted material. Aspectic loosening is the main complication. The surgical pathologist has to identify wear debris (metal, polyethylene, polymethylmethacrylate, chiefly) which promotes a histiocytic granuloma. Some surgical procedures such as cup or resurfacing arthroplasties create a new articular surface and a bone remodeling or necrosis. Cemented joint prostheses show various membrane structures between bone and the cement mantle while there is an association of bone resorption and formation. Non-cemented, porous-coated joint prostheses induce little bone ingrowth, even in satisfactory clinical results. Mechanical factors are predominant in massive limb prostheses. For silicone elastomer implants or artificial ligaments, wear of material promotes many tissular reactions. Often used bone grafts show little creeping substitution process in case of homografts, even well-incorporated on X-rays. More retrieval specimen studies are necessary to delineate precise topographical histological lesions, including non-loosened joint implants.

Bone and Bones↗
PubMed2003

Normal and prosthetic synovial joints are lubricated by surface-active phospholipid: a hypothesis.

Much evidence supports the hypothesis that surface-active phospholipid (SAPL), which imparts the thin hydrophobic outermost lining to the normal articular surface, is the boundary lubricant reducing friction to remarkably low levels. We review this evidence and further hypothesize that SAPL produced in type B synoviocytes will also lubricate prostheses after implantation. This could explain why implanted hips display far less wear than hips in simulated wear trials do, even using protein as the lubricant whereas rougher surfaces can be tolerated in vivo. We introduce the concept that a deficiency of SAPL might explain the selective failure of prostheses just as osteoarthritic articular surfaces are deficient. This, in turn, leads to the replenishment of SAPL, as tested in OA, and the concept of prelubricating prostheses before implantation.

Cartilage, Articular↗
PubMed1986

Autologous blood transfusion in total joint arthroplasty.

In 1974, an autologous blood transfusion program for total joint replacements was established at William Beaumont Hospital. From 1980 through 1984, 396 patients donated 1,619 units of blood. The patients' ages ranged from 23 to 89 years (median, 63 years) in men and 29 to 89 years (median, 67 years) in women. Blood was collected on a weekly basis, if the patient's hematocrit was greater than 34%. Blood collected within 49 days of surgery was maintained in a liquid state; otherwise, it was frozen. Patients with a history of cardiovascular disease received permission from their internist before donating blood. The cost per unit of frozen blood was much higher than that of liquid blood. Autologous blood transfusion is safe, there is no age limitation for blood donors, and blood can be collected at weekly intervals.

Adult↗
PubMed1987

Long-term results of total joint arthroplasty in nonambulatory patients.

The authors conducted a long-term follow-up study of 27 patients, all confined to a bed or wheelchair for at least 6 months, who had total joint arthroplasty to relieve rest pain, correct deformity, and enable independent ambulation. The average duration of nonambulatory status before operation was 3 years (mean, 1 1/2 years), with the longest being 15 years. The patients required an average 3-month hospital stay and an average of three major total joint arthroplasties in the lower extremities. All of the patients were ambulatory at the time of discharge but required some sort of aid. After 1 year, 20 patients (74%) were able to launch independently; 9 (33%) could ambulate without aids; and 14 (52%) could ambulate with aids. At follow-up evaluation 3-12.8 years (average, 6.5 years) after operation, nine patients (33%) ambulated without aids, five (19%) required a single crutch or cane, and nine (33%) required bilateral crutches or a walker, for a total success rate of 85%, which did not deteriorate with time.

Adolescent↗
PubMed2000

A novel transducer for the measurement of cement-prosthesis interface forces in cemented orthopaedic devices.

When a cemented orthopaedic device is being investigated there is a need to estimate the forces at the cement-prosthesis interface. For this reason a miniature transducer was developed that could be included inside the surface of most prostheses. A load cell (based on a piezoelectric sensor) and the required accessories and amplification were custom designed and built. The present work describes the validation that was performed on the piezo sensors alone, when mounted on a simplified structure, and when applied to a hip stem.Linearity, repeatability, reproducibility, and sensibility to shear and axial eccentric loads were tested, yielding satisfactory results. The repeatability on the same sensor was found to be good while reproducibility between sensors was lower. Thus, each sensor was calibrated separately with a second order relationship. Sensitivity to shear and eccentric loads was very low. The overall accuracy of the load cell (including non-linearity, and signal drift) was of the order of about 1%.A hip stem instrumented with four such sensors was successfully implanted in a composite femur, yielding meaningful readouts.Thus, this type of sensor can readily be used to assess the cement-prosthesis interface forces in cemented devices.

Biomechanical Phenomena↗
PubMed2005

Stem-cell-driven regeneration of synovial joints.

Mammalian skeletal motion is made possible by synovial joints. Widespread suffering from arthritis and joint injuries has motivated recent effort to regenerate a stem-cell-driven synovial joint condyle implantable in total joint replacement. A single adult stem cell lineage, mesenchymal stem cells, differentiate to form all components of a synovial joint. Whereas localized joint lesions may be repaired by either cell-based or cell-free approaches, regeneration of the entire articular condyle of the synovial joint is unattainable without tissue-forming cells. A series of experiments are presented here to describe our initial attempts to regenerate a synovial joint condyle in the shape and dimensions of a human mandibular condyle, with both cartilaginous and osseous components derived from a single population of rat mesenchymal stem cells. Upcoming challenges are along several intertwining fronts including structural integrity, tissue maturation, mechanical strength and host integration. The synovial joint condyle may turn out to be one of the first 'human body parts' or organs truly regeneratable by stem-cell-derived approaches. Current approaches to regenerate the synovial joint condyle from stem-cell-derived multiple cell lineages may also offer clues for engineering complex organs such as the kidney or liver.

Animals↗
PubMed2000

Acute metastatic infection of a revision total hip arthroplasty with oral bacteria after noninvasive dental treatment.

The risk of hematogenous bacterial infection of a total joint prosthesis is currently considered to be greatest in the 2 years after arthroplasty or when the patient is chronically ill or immunocompromised, for dental treatments that are considered invasive, with a higher incidence of bacteremia. We report the case of a healthy man who had undergone revision hip arthroplasty 11 months previously and who developed acute signs of infection of the hip prosthesis with an oral organism 30 hours after supragingival dental cleaning, performed with the specific intention to be noninvasive, without antibiotic prophylaxis.

Abscess↗
PubMedDate not supplied

[Interchangeability of the ceramic ball heads of various endoprosthesis systems. Technical report].

Today, the type of hip joint prosthesis implanted is usually chosen on the basis of the patient's age and anatomic conditions, and in particular depending on whether it is a first or second hip replacement. Not infrequently, it is desirable or necessary to combine different prosthesis systems, especially when changing prostheses. In many cases this is possible. The ceramic ball heads of different systems are also interchangeable, provided certain criteria (e.g., manufacturer) are satisfied.

Ceramics↗
PubMedDate not supplied

[Neurologic complications in implantation of knee endoprostheses. A clinical and EMG-documented study].

In a retrospectively studied group of 253 knee joints treated by total replacement, six (2.4%) nerve lesions were clinically diagnosed. In the vast majority there was damage to the peroneal nerve, and in a single case also to the tibial nerve. After between one and three years only two patients still had permanently impaired function. In a second prospective study of 27 patients, examined by EMG before and after surgery, signs of bland, fresh neural damage was found in just under 30% following implantation of a knee joint prosthesis. In none of the cases had clinically manifest defunctionalization symptoms occurred. In the subsequent course, proof of far-reaching remission of the subclinical lesions was obtained, also by EMG. The causes of the perioperatively inflicted nerve lesions are discussed; the correction of axial defects (knee-bending contracture, genu valgum) in particular seems a likely cause of neural damage.

Electromyography↗