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PubMed1982

Stress fracture of the patella following duopatellar total knee arthroplasty with patellar resurfacing.

Stress fracture of the patella can occur with significant frequency following patellar replacement with the duopatellar knee prosthesis. In the first 372 knees with patellar resurfacing, the incidence was 0.7% in rheumatoid arthritis (2 fractures in 286 knees) and 3.5% in osteoarthritis (3 fractures in 86 knees). The incidence may be greater in osteoarthritic patients because they have more function and are generating greater force across the patellofemoral joint. There was an association with osteonecrosis of the patella in at least three cases in which a lateral retinacular release had been performed and the lateral superior genicular artery sacrificed. This vessel should be preserved during a lateral release to save its contribution to the blood supply of both the patella and the lateral skin flap. Initial treatment of the stress fractures can be nonoperative, with surgery necessary only if the patellar prosthesis has become dislodged, or if pain or inadequate active extension persists. If the fracture can not be repaired, patellectomy can yield a good result. To avoid stress fracture, a minimal amount of patellar articular surface should be resected and the peripheral cortex of both the medial and lateral facets preserved. Fewer stress fractures may occur if a smaller fixation lug is used, thereby preserving more patellar bone stock.

Aged↗
PubMed1988

Clinical results with an uncemented plastic tibial component in unicompartmental knee replacement.

To determine the role of unicompartmental knee replacement in knee arthroplasty and, in particular, the design and function of the ICLH (Finsbury Prosthetics Ltd., London, UK) knee prosthesis, the authors report their experience with 18 patients (15 women and 3 men, mean age 73 years), who underwent unicompartmental knee replacement with this prosthesis. The prosthesis failed in five (27.8%) cases, but in the remainder the results were good to excellent over a follow-up extending to 6 years (mean 4.5 years). The main problem with the ICLH prosthesis is the linear wear of the plastic of the tibial component, caused by a sharp radius at the edge of the femoral component. This leads to fracture and breakdown of the tibial portion. Because the short-term results are good but the long-term results are poor, the authors suggest that the ICLH unicompartmental knee prosthesis should be reserved for use in patients whose life expectancy is short.

Aged↗
PubMed2003

[Management of stiffness after total knee arthroplasty: indication for different mobility management in 62 cases].

PURPOSE OF THE STUDY: Stiffness of the knee is a common reason for revision of total knee arthroplasty. Three methods are currently used to mobilize the knee: manipulation under general anesthesia, arthroscopic release, open surgical release. The purpose of the present work was to determine the respective indications of these three procedures in a large single-center study. MATERIAL AND METHODS: We retrospectively assessed all revision procedures without component exchange in patients with a stiff total knee prosthesis. Sixty-two procedures were performed in our institution between 1989 and 2001. All patients were followed for at least one year. There were 34 manipulations under general anesthesia, 18 arthroscopic release procedures, and 10 open surgical release procedures. The three groups were not different for all parameters studied except time interval between implantation of the prosthesis and the mobilization procedure: 17 weeks for manipulation under general anesthesia, 46 weeks for arthroscopic release, 97 weeks for surgical release. A comparable postoperative analgesia and rehabilitation program was instituted for all patients. RESULTS: Range of flexion improved after all 62 procedures: mean 58.4 degrees before the procedure, mean 94.6 degrees at one-year follow-up. Flexion deformity also improved from 7.6 degrees to 2.5 degrees at one year (p=0.001). From surgery to one-year follow-up, there was a decrease in flexion (104.6 degrees to 94.6 degrees ) and an increase in flexion deformity (1.3 degrees to 2.5 degrees ) (NS). The worst postoperative ranges of motion were observed at six weeks after the procedure. Improvement was then observed up to six months but was not significant. There was no improvement in flexion beyond six months after the mobilization procedure. The results of the three techniques were not significantly different. Failures were however more frequent when manipulation under anesthesia was performed more than eight weeks after prosthetic insertion, and when arthroscopic release was performed more than six months after prosthetic insertion (p<0.01). DISCUSSION AND CONCLUSION: We recommend treatment of stiff total knee prosthesis by manipulation under general anesthesis if the procedure is performed less than eight weeks after implantation; a delay of six weeks is even better because intraoperative complications were observed for patients treated between six and eight weeks. Between eight weeks and six months, arthroscopic release should be advised, surgical release thereafter. Whatever the delay, this protocol is appropriate for stiff knee prostheses without infection and without component malposition. Whatever procedure is applied, the definite range of motion is reached six months after the intervention.

Arthroplasty, Replacement, Knee↗
PubMed1998

Materials selection and design for orthopaedic implants with improved long-term performance.

Design and materials selection are equally important in the development of orthopaedic implants. Two case studies are presented to illustrate this: the development of a femoral component of a total hip prosthesis and the study of alternative designs of a tibial component of a total knee prosthesis. Bioactive surface coatings may be applied to enhance the stability of fixation of the implant, even in difficult clinical cases. It is argued that an improved long-term performance of an implant can only be achieved by considering the biomechanics and biomaterials aspects of joint replacement together, and at the same time guaranteeing the quality of surgery by providing the surgeon with better pre-surgical planning systems and advanced surgical tools.

Biocompatible Materials↗
PubMed1992

White blood cell scintigraphy with monoclonal antibodies in the study of the infected endoprosthesis.

Forty-three patients with suspected infection of a hip or a knee prosthesis were studied with white blood cell scintigraphy (WBC), using technetium-99m (n = 37) or iodine-123 (n = 6) labelled monoclonal mouse antibody (MoAb). Previously, all patients had undergone skeletal scintigraphy, which was performed as a three-phase study in 33 cases. The final diagnosis was established by open surgery, histology and culture in 37 cases, by puncture and culture in 3 cases, and by clinical follow-up of at least 6 months in 3 cases. Eighteen prostheses were infected, 25 uninfected. The delayed phase of skeletal scintigraphy had a sensitivity of 92%, a specificity of 24% and an accuracy of 48% in the detection of infection. The perfusion and blood pool activity of the three-phase bone scan had a sensitivity of 67%, a specificity of 71% and an accuracy of 70%. The diagnostic value of WBC was sensitivity 89%, specificity 84% and accuracy 86%. WBC with 99m-Tc-MoAb is easy to perform and always available. Its diagnostic accuracy is similar to conventional WBC scintigraphy with either indium-111 or technetium-99m.

Adult↗
PubMed1979

Computer design synthesis of a below knee-Syme prosthesis.

A detailed design synthesis analysis of the BK Syme prosthesis is provided, to determine the socket's cutout orientation size and shape, cutout fillet shape, socket wall thickness distribution and the reinforced fiber distribution in the socket wall, for a minimally stressed structurally safe lightweight prosthesis. For analysis purpose, the most adverse socket loading is obtained at the push-off stage of gait; this loading is idealised as an axial in-plane loading on the bottom edge of the circular cylindrical socket shell whose top edge is considered fixed. Finite element stress analysis of the socket shell (with uniform and graded wall thickness) are performed for various orientations of the cutout and for various types of corner fillets. A lateral cutout with a streamline fillet is recommended. The wall material (i.e., thickness) distribution is determined so as to minimise the stresses, while ensuring that the wall material's stress limits are not exceeded. For such a maximally-stressed lightweight socket shell, the panels in the neighbourhood of the cutout are checked to ensure that they do not buckle under their acquired stresses. A fiber-reinforced laminated composite socket shell is also analysed, to recommend optimum variables in orientations and densities of reinforcing fibers.

Ankle↗
PubMed1986

An in vitro simulation study of impulsive force transmission along the lower skeletal extremity.

Several investigators have revealed that a relationship exists between articular cartilage deterioration and the mechanical stress that results from transient impulsive forces created in the lower extremity during gait. This study is an investigation of the transmission of impulse waves through the lower extremity and the effect of knee pathology and prosthetic knee replacement on their transmission. An in vitro experiment is performed using human cadaver specimens that are instrumented with accelerometers. The distal end of the tibia is impacted with a vibration shaker to simulate heel strike. The results indicate that the normal knee joint is able to attenuate 59% of the transient peak force applied to it by the tibia. This attenuation capacity is reduced by knee pathology and decreases further with implantation of a knee prosthesis. The results indicate that abnormalities at the knee may increase the risk of degenerative changes at the ankle, hip and in the spine due to increased transient impulsive forces.

Aluminum↗
PubMed1998

Immunohistochemical analysis of matrix proteolytic enzymes in the periprosthetic tissue in the patients with loosening prostheses.

Regional periprosthetic bone resorption plays an important role of prosthesis loosening. In order to study the possible mechanisms of loosening, we investigated the presence of matrix proteolytic enzymes in the periprosthetic tissue by immunohistochemical technique in 72 patients undergoing revision operation of loosened joint prosthesis, including 22 males and 50 females and aged from 19 to 88 years (mean, 61.7 years). Thirty-nine patients had a loosened hip prosthesis (18 males and 21 females) whereas 33 patients had a loosened knee prosthesis (4 males and 29 females). Tissue specimens collected during revision surgery underwent thin slide sections and H & E staining, and were observed under light microscopy and polarized-light microscopy. The results showed many macrophages, histiocytes, fibroblasts, as well as many phagocytosed metal debris and polyethylene debris in the periprosthetic tissues, suggesting an active bone resorption. Furthermore, we used immunohistochemical techniques to detect the distribution of matrix proteolytic enzymes in periprosthetic tissue, including lysosome enzymes (cathepsin B, cathepsin D and cathepsin G), and matrix metalloproteinase (MMPs, MMP-1, MMP-2, MMP-3). The immunostaining were classified as strong positivity, > 70% positive cells; moderate positivity, 20-70% positive cells; weak/negative, < 20% positive cells. The results showed that cathepsin B, cathepsin D and cathepsin G were found in most fibroblasts and macrophage-like cells, including multinuclear giant cells and epithelioid cells. MMPs were found in most fibroblasts and macrophage-like cells, as well as a scant amount in the extracellular matrix. These enzymes were also found in or around blood vessels, the endothelial cells in the richly vascularized tissue. All negative controls showed no staining. The results of immunoreactive staining ranged from 61.1% to 68.1% of strong to moderate positivity. Since these enzymes were related to the degradation of matrix protein, they may be related to the periprosthetic bone resorption. The further clinical significance needs further investigation.

Adult↗
PubMed2003

Dislocation of rotating hinge total knee prostheses. A biomechanical analysis.

BACKGROUND: Symptomatic instability and implant dislocation are occasionally encountered in patients with a rotating hinge total knee prosthesis. A biomechanical study of rotating hinge total knee implants was performed to determine the association between the design (length and taper) of the central rotational stem and the stability of the implant. METHODS: The stem lengths and tapers of knee implants made by seven manufacturers were measured. The tilting laxity of each design was tested by measuring the degree of tilting of the central rotational stem within the tibial housing that occurred with increasing amounts of distraction. The maximum amount of distraction that was possible before the stem dislocated was determined for each design. RESULTS: Implant designs with a short and/or markedly tapered central rotational stem had the greatest tilting, laxity, and instability of that stem. The Howmedica, Techmedica, Intermedics/Sulzer Medica, and Wright Medical Technology/ Dow Corning Wright designs required > or = 39 mm of distraction before they dislocated. The Biomet knee implant required 33 or 44 mm of distraction to dislocate, depending on the thickness of the polyethylene tray that was utilized. The S-ROM knee required only 26 mm of distraction before dislocation occurred. CONCLUSIONS: The measurements confirmed that the shorter the stem and the greater its taper, the greater the instability and laxity at any given amount of joint distraction.

Biomechanical Phenomena↗
PubMed1991

Effects on leukocyte function by arthroplasty. Thromboplastin activity and oxygen-derived free radicals studied in rheumatoid arthritis and arthrosis.

We examined thromboplastin activity (TA) of monocytes and release of oxygen-derived free radicals (ODRFs) from monocytes and granulocytes before and after implantation of a hip or a knee prosthesis in 7 patients with rheumatoid arthritis and in 8 patients with arthrosis. Monocyte TA rose threefold on the first postoperative day in the rheumatoid patients, but was unaltered postoperatively in the arthrosis patients. Granulocyte chemiluminescence doubled in the arthrosis group on the second postoperative day, but was unaltered in the rheumatoid patients. Monocyte chemiluminescence was not influenced by the operation. Thus, leukocytes from the rheumatoid patients responded differently from surgical trauma when compared with leukocytes from the arthrosis patients. This difference may have an impact postoperatively.

Arthritis, Rheumatoid↗
PubMed1984

[Geometric total knee arthroplasty--follow-up for an average of six years].

Geometric total knee prosthesis was applied for reconstruction of 70 destructive knee joints in 56 patients from November 1973 through March 1979. The average follow-up period extended to six years and seven months. Eleven patients had died and four could not be located. Eighty-one percent of the remaining arthroplasties disclosed little or no pain at the time of the review. Pain in the patellofemoral joints was an insignificant problem in this series. The absence of radiolucent zone at the tibial cement-bone interface was noted in only 20.4% of the roentgenograms. New formation or progression of radiolucent zone after six months was found in 36.7%. Displacement of the marker wires seen in serial roentgenograms existed in 51.0% of the knees. The tibial component was fractured in one patient.

Adult↗
PubMed1984

The long-term results of Stanmore total knee replacements.

Between 1969 and 1971 20 prototypes of the Stanmore total knee prosthesis were used to replace severely arthritic knees in 18 patients. Seven patients died before the final follow-up and one had to have her leg amputated because of deep infection; in none of these patients had the prosthesis become loose. Ten patients (11 knees) were reviewed at least 10 years after operation. There was no significant clinical deterioration in 7 of these 11 surviving knees when the results at one year were compared with those at 10 years.

Adult↗
PubMed1983

Knee arthrodesis following prosthesis removal. Use of the Wagner apparatus.

Arthrodesis after the removal of a knee prosthesis is often hampered by the small area of contact of the bony surfaces and by pre-existing infection. Conventional systems of external fixation and compression frequently fail to achieve stability but the addition of the Wagner leg-lengthening apparatus applied anteriorly and adjusted to give compression ensures rigid external fixation. Four knees in four patients were treated using this technique; the treatment followed the removal of infected prostheses in three knees and painful fibrous ankylosis after the removal of the prosthesis in the other. All obtained a sound arthrodesis.

Adult↗
PubMed2006

Distal femur replacement is useful in complex total knee arthroplasty revisions.

UNLABELLED: Revision total knee arthroplasty can be considerably more difficult in cases involving severe bone loss, complete absence of collateral ligaments, and persistent periprosthetic supracondylar femoral fractures. Modular segmental endoprosthetic distal femur replacement is a limb salvage option when other surgical options are unfeasible. The clinical performance of rotating hinge knee prostheses has greatly improved with the evolution of second and third generation designs. The increased freedom of rotation decreases the prosthetic bone stresses and the longevity. While designs have improved, the prostheses still do not match the function and longevity of condylar components with approximately a 90% survivorship at 20 years. The modular endoprosthesis rotating hinge knee prosthesis is useful for total knee arthroplasty revision in patients with inadequate bone stock, ligamentous instability, or difficult supracondylar femur fractures, especially in low demand elderly patients. LEVEL OF EVIDENCE: Therapeutic study, level V (expert opinion). See Guidelines for Authors for a complete description of levels of evidence.

Aged↗
PubMed1998

Problems with the Rotaflex: a 10 year review of a rotating hinge prosthesis.

The results of the first 10-year review of the Rotaflex total knee prosthesis are presented. Loosening, fracture, implant failure, and damage to the extensor mechanism have been frequent findings. Of 25 implants reviewed, an arthrodesis has been performed in 4 patients and an amputation in 2. Surgery has been declined in a further 4 patients. A brace is required by 7 of 19 patients in whom the prosthesis has not been removed, and the results of surgery are considered poor in 13 of these 19 patients. With an overall complication rate of almost 80%, there would appear to be no place for this prosthesis despite its continued availability.

Activities of Daily Living↗