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PubMedDate not supplied

[Mechanical stress on the osseous tibial plateau in complement joint surface replacement--a finite element analysis].

For an unconstrained bicondylar sledge knee prosthesis the mechanical load of the bony support is crucial. For a design of a tibial component of such a prosthesis with improved anatomical features allowing a complete cortical support of the rim of the prosthesis, a finite element study was performed. Stress reactions of the bone for different implantation modes were calculated. Irrespective of the bony support of the prosthesis, tensile stresses are always transferred at the interface prosthesis/bone into the bone. For a complete cortical support of the rim of prosthesis, the areas of tensile stress in the bone are closely related to areas of high compression stress. If there is cortical support of the prosthesis only on the medial side due to an undersized prosthesis, this is only of minor influence on the stress pattern in the bone. However, if there is cortical support of the prosthesis only on the lateral side, there are large areas of tensile stresses in the lateral compartment of the tibial plateau. However, tensile stress transfer in the tibial plateau must be regarded as unphysiologic and therefore unfavourable. Therefore, if intraoperatively complete cortical support of the prosthesis cannot be achieved a more medial cortical support of such a prosthesis should be preferred to a lateral cortical support.

Biomechanical Phenomena↗
PubMed1995

Bone grafting in cemented knee replacement. 45 primary and secondary cases followed for 2-5 years.

From 1989 through 1993, we treated 36 knees in 30 patients by bone grafting (31 tibial and 14 femoral grafts) and a cemented total knee prosthesis. We used 23 morsellized and 22 solid bone grafts. After a mean follow-up period of 3 years, the mean clinical (IKS) knee score was 90. Radiographic signs of incorporation of the tibial bone graft were noted in 28 cases. Of the 8 solid femoral bone grafts, we observed twice a disintegration of the graft.

Adult↗
PubMed2002

[Surgical complications and their treatment options in total knee replacement].

INTRODUCTION: One of the most important achievements of modern orthopedics is the treatment of degenerative disorders of the knee joint with endoprostheses. The most often used type of knee prosthesis implanted in our times is the total condylar one. With increasing numbers of prosthesis operations the number of complications is also increasing. AIM: Knowledge of diagnostic and treatment principles of complications is important for all institutions applying knee prostheses. The aim of present study is to report the authors' experience with the most important surgical problems following knee arthroplasty. PATIENTS/METHODS: At the Department of Orthopedics of the University of Pécs between 1993 and 1999 344 primary total condylar prostheses were implanted. Based on their own cases, the authors show the most important surgical problems after total knee arthroplasty. RESULTS: In their patient sample they observed infections, patellofemoral complaints and supracondylar femoral fractures being the commonest complications. Besides these problems they faced with some rare ones, like instability of the artificial joint and temporary peroneal palsy. Probably because of the relatively short follow up period, the authors had to perform only one revision procedure due to aseptic mechanical problems. The incidence of the most common complications in the authors' patient material is described as well as the principles and results of the applied treatment methods. Own experiences are compared with data from the literature. CONCLUSIONS: Although knee arthroplasty complications can be variable and followed by serious consequences, even the most significant ones can be managed with methods which provide the option of healing and restoration of knee functions.

Arthroplasty, Replacement, Knee↗
PubMedDate not supplied

Ochronosis: a report of a case and a review of literature.

A patient with alkaptonuria and ochronotic pigment deposited in articular cartilage and sclerae clinically manifested a serious osteoarthritis of the peripheral and axial joints and synchondrosis, typically involved in long lasting cases of this hereditary defect of homogentisic acid oxidase. This is the first patient with this disorder reported, where a non-cemented total knee prosthesis (PCAR) was applied on both knees. This was possible due to the good quality of the bone stock, which did not seem to be impaired by ochronosis. Our patient had no cardiac symptoms or murmurs, but had a slight calcification in the annulus of aorta observed with echocardiography, a useful new method for screening this disease manifestation. A third new aspect reported is the immunopathology of the synovial tissue. Small pieces of torn-off cartilage were seen embedded in the synovial stroma. This was associated with a slight hyperplasia of the C3bi-receptor positive and proline hydroxylase positive type A and B synovial lining cells. Perivenular infiltrates contained CD2 positive T lymphocytes, mostly belonging to the CD4 subset, and some C3bi-receptor positive monocytes. Activated CD25 positive and immunoglobulin light chain positive T and B lymphocytes were absent or few. Because modern medicine has much to offer to those suffering from this ancient inborn error of metabolism in the form of new specific diagnostic methods and new surgical modes of treatment, such as endoprosthesis surgery and cardiac valve replacement, we also present a literature overview of this interesting condition.

Dioxygenases↗
PubMed1981

The Attenborough total knee arthroplasty.

A follow-up study was performed on 20 total knee arthroplasties of the Attenborough type in 15 patients. The follow-up term was from one to three years. In 16 cases the knee joint degeneration was caused by rheumatoid arthritis and in four cases by osteoarthrosis. Knee flexion improved from an average preoperative value of 17 degrees to 84 degrees, to an average of 3 degrees to 92 degrees. In one case (5%) a deep infection developed. In another case there was roentgenographic and clinical evidence of prosthetic loosening. Four patients were left with significant patellofemoral pain. With the exception of the infected knee, all patients showed significant improvement in their walking distance. Subjectively, 67% of the patients were satisfied or delighted, 26% felt improved and 7% were dissatisfied. These preliminary results with the Attenborough total knee prosthesis are comparable with the results of other authors; the indications seem limited to patients with restricted physical activity and severe deformity of the knee.

Adult↗
PubMed1995

Interlocked supracondylar intramedullary nails for supracondylar fractures after total knee arthroplasty. A new treatment method.

Supracondylar fractures in patients with total knee prostheses are challenging surgical problems for which there has been no single satisfactory method of management. The authors present four cases to show that a fully cannulated, closed-section, stainless steel supracondylar intramedullary nail can be inserted in a closed fashion through a 3 cm longitudinal patellar splitting incision between the metal condyles of a nonconstrained femoral component of a total knee prosthesis. The nail can be interlocked with percutaneous screws and provides primary stability of a supracondylar femoral fracture, even in the presence of total knee and total hip prostheses.

Aged↗
PubMed2004

The modular segmental kinematic rotating hinge for nonneoplastic limb salvage.

From January 1980 to July 1998, 25 patients (26 knees) were treated with an arthroplasty using a Modular Segmental Kinematic Rotating Hinge total knee prosthesis for nonneoplastic limb salvage. The indications included: nonunion of a periprosthetic femur fracture (11 knees), severe bone loss and ligamentous instability (eight knees), nonunion of a supracondylar femur fracture (four knees), acute periprosthetic fracture (one knee), fracture of a previous hinge (one knee), and prior resection arthroplasty (one knee). The average age of the patients was 72.3 years. Twenty-two arthroplasties were revisions. The average followup was 58.5 months. At the latest followup, knee extension averaged 2.4 degrees and flexion averaged 93.6 degrees. The Knee Society knee score improved from an average of 45.4 preoperatively to 75.5. Preoperatively, functional scores averaged 8.6 and improved to 25. Complications occurred in eight patients. The most common was deep infection (five patients). The use of the Modular Kinematic Rotating Hinge for nonneoplastic limb salvage represents a small proportion (0.14%) of all primary and revision knee arthroplasties done at our institution. The indications for the surgery are for a highly complex and small subset of patients. The patients in the current study gained significant improvement in overall range of motion, Knee Society knee scores, and functional scores when this prosthesis was used.

Aged↗
PubMed1983

Effects of thermal therapy on rehabilitation after total knee arthroplasty. A prospective randomized study.

The role of local heat or cold therapy used in conjunction with exercise in the rehabilitation of total knee arthroplasty patients was investigated. Thirty-six osteoarthritic patients were analyzed. Parameters evaluated were range of motion, swelling about the knee, and pain. All patients received the total condylar knee prosthesis and began range of motion rehabilitation fourteen days after operation. Results showed that temperature alteration does not augment passive range of motion after total knee arthroplasty. It was also shown that cold application decreases swelling as compared with heat. Additionally, the application of cold partially alleviates the discomfort of the rehabilitation process in certain patients.

Aged↗
PubMed1984

The long-term results of Stanmore total knee replacements.

One hundred and three sequential Stanmore knee replacements were reviewed retrospectively on two occasions with a maximal follow-up period of nine years three months. This knee prosthesis, which is hinged, was successful in alleviating pain, stabilising an unstable knee and modestly increasing the arc of flexion. Walking capacity was increased and flexion contractures were reduced. There were seven cases of infection and four of fracture around the prosthesis. All these proved difficult to treat and two knees with both fracture and infection needed amputation. Eight knees were revised for aseptic loosening and a further 14 were found to have radiological signs of loosening. The results have been analysed by the methods advocated by Tew and Waugh and give a cumulative success rate of 80 per cent at seven years, provided success is judged solely by whether the prosthesis is still in situ. The role of the Stanmore knee as a primary arthroplasty is discussed.

Adult↗
PubMed2002

Relative motion of a mobile bearing inlay after total knee arthroplasty--dynamic in vitro study.

OBJECTIVE: The purpose of this study was to measure the in vitro range of motion of a mobile bearing inlay knee prosthesis under dynamic isokinetic loading conditions. Additionally, the effect on the range of motion of rotational malalignment of the tibia baseplate was determined. DESIGN: Specimens with implanted knee prostheses were mounted onto a custom built knee simulator. 3-D inlay movement was measured by an ultrasonic tracking system. BACKGROUND: More recent knee prostheses include mobile bearing inlays type designs. These systems are intended to allow higher conformity of the tibiofemoral joint and thereby decrease contact stress without decreasing the knee's range of motion. METHODS: Dynamic testing in the knee simulator mimicked both the speed and resulting moment of a knee isokinetic extension test. The tibia baseplate was first implanted with no rotational malalignment, followed by sequential internal and external rotation of upto 15 degrees. RESULTS: Correctly aligned, the inlay center moved 3.5 mm (SD, 1.5 mm) posterior during extension. With the tibia baseplate externally rotated more than 10 degrees the movement pattern changed. CONCLUSION: At up to 10 degrees of rotational malalignment the primary motion pattern of the mobile bearing is maintained. However, beyond 10 degrees unintended motion may occur. RELEVANCE: These test results correlate to radiographic measurements of in vivo movements of mobile bearing inlays showing "paradoxical" movement of the mobile inlay compared to physiologic meniscal movement.

Biomechanical Phenomena↗
PubMed1993

The effect of femoral component position on the kinematics of total knee arthroplasty.

In a laboratory study using seven fresh-frozen anatomic specimen knees, the effect of total knee arthroplasty on the three-dimensional kinematics of the patella, femur, and tibia were measured. Experiments were performed in the intact knee, after division of the anterior cruciate ligament (ACL), after total knee arthroplasty, and after 10 degrees internal rotation, 10 degrees external rotation, 5-mm medial shift, and 5-mm lateral shift of the femoral component on the femur. The presence of a high lateral ridge on the anterior surface of the femoral component effectively prevented patellar subluxation or dislocation, but displaced and tilted the patella medially. Internal rotation or medial displacement of the femoral component exaggerated this medial patellar displacement and shift. External rotation of the femoral component corrected it, except at flexion angles greater than 100 degrees, where the femur was shifted medially on the tibia and externally rotated 15 degrees. This combination produced a net 10-mm medial displacement of the patella relative to the tibia at 120 degrees knee flexion. Lateral placement of the femoral component compensated for the effect of the high lateral ridge and allowed more normal patellar tracking while allowing tibiofemoral motions similar to those seen after sectioning of the ACL. The kinematics of the patellofemoral and tibiofemoral joints were not reproduced with a total knee prosthesis that sacrifices the ACL. When using a prosthesis with a high lateral ridge, lateral placement of a femoral component prevented patellar dislocation and allowed patellar tracking patterns similar to those seen in the intact knee without further altering tibiofemoral motions.

Adult↗
PubMed1992

Long-term results of total condylar knee arthroplasty in rheumatoid arthritis.

We have reviewed at an average period of ten years the results of 71 consecutive primary arthroplasties with the Insall-Burstein total condylar knee prosthesis in patients with rheumatoid arthritis. Their mean age at surgery was 52 years (24 to 72). At follow-up the overall results (Hospital for Special Surgery knee rating score) were excellent or good in 77%, fair in 11% and poor in 11%. There was residual pain in only 5% of patients with prostheses in situ; 58% could walk more than 500 m, and the median range of motion was 108 degrees. Eight knees had been revised. Five underwent arthrodesis because of deep infection and three needed revision arthroplasty for mechanical loosening. The crude survival rate of the arthroplasties was 89%. The presence of radiolucency around the tibial component correlated significantly with the severity of residual pain.

Adult↗
PubMed1997

Ceramic unicompartmental knee arthroplasty for spontaneous osteonecrosis of the knee joint.

Unicompartmental replacement with a ceramic knee prosthesis was performed in 10 patients with spontaneous osteonecrosis. The follow-up period averaged 42 months, with a range of 24 to 68 months. All of the knees received a Kyocera unicompartmental knee arthroplasty and all patients were evaluated using The Knee Society Clinical Rating System. The mean knee score increased from 50.6 to 90.8 at the last follow-up, showing no deterioration with time. All of the patients showed marked improvement of pain and excellent or good results were obtained in all cases. None of the patients had progressive radiolucency wider than 2 mm at the final follow-up. Ceramic unicompartmental knee arthroplasty is an acceptable treatment for spontaneous osteonecrosis of the knee joint; a satisfactory postoperative range of motion can be achieved, there are few complications, and a high initial success rate.

Aged↗
PubMedDate not supplied

[Bicondylar knee replacement--an intermediate term evaluation of the Genesis prosthesis].

65 knee arthroplasties in 60 patients (5 x both sided, 49 x female, 11 x male) with a Genesis Total Knee System (54 x cemented, 6 x cementless, 4 x tibial cemented/femoral cementless, 1 x tibial cementless/femoral cemented) were evaluated according to the Knee Society Score and the HSS Score with a medium follow up of 4 years und 5 months (3 years and 4 months to 5 years and 11 months). In 48 patients the diagnosis was gonarthrosis, in 17 patients it was rheumatoid arthritis. The medium postoperative Knee Score was 80.9 points, the Function Score was 73.7 points. The HSS Score obtained 80.9 points. 87.7% of the patients were excellent or good. The Genesis Total Knee arthroplasty has proved to be reliable for osteoarthritis and rheumatoid arthritis in medium term.

Aged↗
PubMed1978

The Attenborough total knee replacement.

The stabilised gliding knee prosthesis is a compromise between hinged joints and condylar prostheses. It is a two-piece implant designed to allow normal gliding movements of flexion and extension and which, stabilised by a connecting rod between the femoral and tibial components, allows a designed laxity of rotation and lateral movements. A modification of the original femoral component is described. Two hundred and forty-five knee replacement operations have been done between January 1973 and September 1977 and the results are reported. The results using this prosthesis are at least equal to those using hinged or condylar prostheses. So far there has been no case of spontaneous loosening of the components and the implant can be used in patients who, because of severe deformities and instability, are unsuitable for condylar prostheses.

Adult↗
PubMed1982

UCI total knee replacement. A follow-up study.

Using the UCI (University of California at Irvine) total knee prosthesis, an arthroplasty was performed in ninety-seven patients (121 knees) from 1972 through 1977. I examined eighty of these patients (100 knees) at three to eight years after the operation and it was necessary to either perform or recommend further surgery in twenty-five of them (twenty-seven knees). These results were designated as failures. The knees in valgus angulation that failed typically did so within the first year because of medical instability and patellar dislocation. The knees in varus angulation that failed typically did so one to six years after operation because of loosening of the tibial component. When failure became established, each knee was found to have reverted to its preoperative angular deformity, indicating that deforming factors were still operative. I suspect that ligament imbalance may have contributed to many of these failures. The surface area and stiffness of the 5.0 and 7.5-millimeter-thick tibial components of the original UCI prosthesis were not sufficient to prevent loosening and subsidence. Constraint between the tibial and femoral components was not sufficient to prevent subluxation or dislocation if soft-tissue release was needed for correction of deformity. Prompted by this experience, total knee arthroplasty using the UCI device has been discontinued at the Ochsner Medical Institutions.

Evaluation Studies as Topic↗
PubMed2001

Temporary articulating methylmethacrylate antibiotic spacer (TAMMAS). A new method of intraoperative manufacturing of a custom articulating spacer.

A temporary articulating antibiotic-impregnated cement spacer for use during the first stage of a two-stage revision of a total knee replacement that had failed because of infection was developed by one of us (W.M.G.). It is simply a knee prosthesis made of methylmethacrylate and antibiotics that is manufactured intraoperatively with use of instruments, medications, and supplies that are already available at most hospitals. This construct allows for motion of the knee during treatment of the infection, thereby reducing the risk of loss of motion after subsequent revision. The technique has been successfully utilized in five patients since 1999 and has now become our standard treatment method.

Anti-Bacterial Agents↗
PubMed2003

Optimization of the geometry of total knee implant in the sagittal plane using FEA.

The aim of this research was to investigate the optimization of the geometry of an UHMWPE type of knee implant in the sagittal plane with minimum amount of wear. Finite element analysis has been used to analyze our proposed 780 models consisting of different design parameters. Maximum stress occurring in the whole tibial component, on the surface or subsurface of the plate, was considered as a design parameter to evaluate the wear condition. By avoiding the small contact area and high stresses in the tibial part, the maximum safe flexion angles have been determined. Other effective design factors such as implant stability, roll back distance, patella lever arm, and minimum bone resection have also been considered. Taking into account the variable parameters in the geometry of the implant parts, all possible models for the femoral component, which is made from metal, and the tibial component, which is made from UHMWPE, have been built in ANSYS and analyzed in the sagittal plane. By considering the effective mechanisms of wear in polyethylene, the results of the analyses were used to find the optimized geometry of a knee implant. This is the model, which is expected to experience the minimum wear, besides having some other properties of an ideal knee prosthesis.

Computer Simulation↗