Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Knee Prosthesis”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 703 records · Page 39Linked to original sources
PubMed2006

Posterior cruciate ligament substitution is not essential for excellent postoperative outcomes in total knee arthroplasty.

The study compared postoperative range of motion (ROM) and functional outcome of total knee arthroplasty (TKA) with a posterior cruciate ligament (PCL)-substituting knee prosthesis compared with an ultracongruent PCL-sacrificing design. Two hundred nine patients underwent primary TKA. Posterior stabilized design (121) and highly conforming, PCL-sacrificing, ultracongruent design (88) TKAs were reviewed. Surgeon, surgical approach, and a hyperflexion postoperative rehabilitation protocol were the same. Results showed significant improvement in knee flexion, ROM, Knee Score, and Function Score within each group. Postoperative mean total ROM was slightly higher with the posterior stabilized design. The 2 groups were the same postoperatively in the improvement in ROM, Knee Score, Function Score, satisfaction level, among other activity metrics. There was no clear evidence proving superiority and the need for posterior stabilization in PCL-sacrificing TKA.

Aged↗
PubMed2002

Comparison of two total knee prostheses on the incidence of patella clunk syndrome.

The patella clunk syndrome is not an uncommon complication, particularly after posterior-stabilized (PS) total knee arthroplasty. The present study was a consecutive unselected series comparing the incidence of the patella clunk syndrome amongst two comparable groups of elderly patients with knee arthritis implanted with the Insall-Burstein (IB II) total knee system and the newer NexGen Legacy total knee prosthesis. While 7.5% of patients in the PS IB II group developed patella clunk syndrome, none occurred in the NexGen group (P=0.05). We believe the difference is due mainly to a change in the design of the prosthesis, especially the more posterior intercondylar box and femoral cam of the NexGen femoral component.

Aged↗
PubMed2002

Functional analysis of the effect of the posterior stabilising cam in two total knee replacements. A comparison of the Insall/Burstein and Bisurface prostheses.

The Bisurface knee prosthesis (BP) has a posterior stabilising cam (ball-and-socket joint) in the mid-posterior region of the femorotibial joint in an attempt to improve the range of movement. Based on an in vitro weight-bearing study contact areas of the Insall/Burstein 2 (IB2) and the BP knee were compared using pressure-sensitive films. The stability afforded by the cam was evaluated by means of dislocation distances in the vertical and horizontal planes. Significant adverse anterior translation in mid-flexion was not observed with the BP knee since the cam was effective above 60 degrees of flexion. At flexion of 60 degrees or more, the total contact areas were larger, as the cam represented a weight-bearing surface. The dislocation distances for the BP knee compared favourably with those for the IB2 knee. We conclude that the cam of the BP knee allows good movement, stability and wear.

Arthroplasty, Replacement, Knee↗
PubMed1986

Tibial component fixation in knee arthroplasty.

Using roentgen stereophotogrammetric analysis (RSA), the integrity of the bond between the tibial component and the tibia was studied in seven knees, implanted with a cemented Kinematic total knee prosthesis for gonarthrosis. Migration ranging from 0.3 to 1.9 mm over a two-year period occurred in all seven cases. Displacement, induced by external forces, ranging from 0.2 to 1.0 mm was observed in five cases. Measurable migration and inducible displacement may be the rule rather than an exception in total knee arthroplasty (TKA). Accordingly, absolute rigid fixation would not be necessary for successful function of a TKA.

Aged↗
PubMed2005

A study of the effect of tibial tray rotation on a specific mobile bearing total knee arthroplasty.

We presumed that a particular mobile-bearing knee prosthesis would cope with tibial tray rotation about its longitudinal axis. We studied the tibiofemoral and patellofemoral joints to assess this. The prosthesis was mounted on a specially designed jig. The tray was externally rotated in 5 degrees increments and put through a range of flexion. We found that increasing tibial tray rotation caused excessive polyethylene loading and, eventually, medial femoral component liftoff. The patellofemoral joint showed increasing lateral patella facet contact. Surprisingly, this mobile-bearing prosthesis could not cope with tibial tray rotation. It required the tibial tray to be neutrally aligned to the femoral component to avoid excessive polyethylene loading.

Arthroplasty, Replacement, Knee↗
PubMed2003

Meniscal bearing uncemented total knee arthroplasty: early clinical results at a minimum 2-year review.

A prospective study of early clinical and radiologic outcome of the Motus (Osteo, Selzach, Switzerland) meniscal bearing total knee arthroplasty was performed. We reviewed the first 75 consecutive prostheses in 62 patients, implanted over a 4-year period. The mean follow-up was 2.5 years. Average preoperative knee score was 97 out of 200 (Knee Society score, 43; functional score, 54) and at 2-year review was 179 out of 200 (Knee Society score, 87; functional score, 92). Average postoperative flexion at 2 years was 113 degrees. No meniscal bearing subluxation, dislocation, or breakages occurred. Radiologically, there was no evidence of subsidence or osteolysis. Our results support the continued use of this meniscal bearing knee prosthesis. It is important to confirm, however, an equal flexion and extension gap without proximal joint line migration.

Aged↗
PubMed2002

Correlation between condylar lift-off and femoral component alignment.

The current study analyzed subjects having a total knee arthroplasty to determine the incidence of condylar lift-off and correlate lift-off with the alignment of the femoral component with respect to the transepicondylar axis. Twenty-five subjects, implanted with a posterior stabilized total knee prosthesis, were asked to do weightbearing deep knee bends while under fluoroscopic surveillance. The two-dimensional fluoroscopic images were converted into three-dimensional images using a fully automated computer model-fitting technique. Each subject then was assessed for the incidence of condylar lift-off. The five subjects having the maximum amount of lift-off were reanalyzed for comparison using computed tomography. Using digitization, the angle between the posterior femoral condylar line and the transepicondylar axis was measured and correlated with the presence of femoral condylar lift-off. The incidence of condylar lift-off was significantly less for subjects in this study compared with subjects reported in previous fluoroscopic studies. Forty percent (10 of 25) of the subjects experienced condylar lift-off. The maximum amount of lift-off was 2.3 mm and the average for subjects experiencing lift-off was 1.4 mm. There also was a distinct correlation between femoral component alignment and condylar lift-off. Using computed tomography, it was determined that 69.2% of the subjects had a correlation between condylar lift-off and malalignment of the femoral component relative to the epicondylar axis. Placement of the femoral component parallel to the transepicondylar axis seems to lessen the incidence of femoral condylar lift-off and may reduce polyethylene wear by reducing eccentric edge loading.

Arthroplasty, Replacement, Knee↗
PubMed1998

Isolated metal-backed patellar component revision following total knee arthroplasty.

BACKGROUND: Twenty-two consecutive revisions for failed metal-backed patellar components following total knee arthroplasty in 17 patients were retrospectively reviewed. All had similar total condylar knee prosthesis inserted with retention of the posterior cruciate ligament and resurfacing of the patella with a metal-backed component. There were 3 male and 14 female patients. RESULTS: The mean time to failure of the patellar component was 60 months (range 26 to 93 months). The majority of patients presented with metallic crepitus (86.4%) and knee pain (72.7%). At surgery, full thickness polyethylene wear exposing the metal-backing was present in 81.8% with surface damage of the femoral components present in 40.9%. All 22 cases underwent successful isolated patellar component revision with all polyethylene patellar components. CONCLUSION: Resurfacing of the patella in total knee arthroplasty with metal-backed patellar components carries a significant risk of early failure and the use of these components is no longer practised at our institution.

Aged↗
PubMed1992

Capacitively coupled electrical field in the treatment of a leg fracture after total knee replacement.

Electrical stimulation has been used as treatment for nonunions of fractures since the early 1950s, with a reported success rate of 80-85%. We report a case of nonunion of a tibial fracture below a revised total knee prosthesis treated with a capacitively coupled electrical field. After 3 months of treatment, consolidation of this difficult fracture was evident with abundant callus formation.

Aged↗
PubMed2003

Factors affecting the durability of primary total knee prostheses.

BACKGROUND: Failure of total knee arthroplasty is problematic. The purpose of this study was to evaluate the factors that influence the durability of a primary total knee prosthesis. METHODS: A survivorship analysis of 11,606 primary total knee arthroplasties carried out between January 1, 1978, and December 31, 2000, was performed. An analysis of patient and implant-related factors affecting survivorship was done with use of a multivariate Cox model. RESULTS: The survivorship was 91% (95% confidence interval, 90% to 91%) at ten years (2943 knees), 84% (95% confidence interval, 82% to 86%) at fifteen years (595 knees), and 78% (95% confidence interval, 74% to 81%) at twenty years (104 knees) following the surgery. Prosthetic survivorship at ten years was 83% for patients fifty-five years of age or less compared with 94% for those older than seventy years of age (p < 0.0001), 90% for those with a diagnosis of osteoarthritis compared with 95% for those with inflammatory arthritis (p < 0.005), and 91% for those with retention of the posterior cruciate ligament compared with 76% for those with substitution of the posterior cruciate ligament (a posterior stabilized prosthesis) (p < 0.0001). Survivorship at ten years was 92% for nonmodular metal-backed tibial components, 90% for modular metal-backed tibial components, and 97% for all-polyethylene tibial components (p < 0.0001). Survivorship at ten years was 92% for prostheses fixed with cement compared with 61% for those fixed without cement (p < 0.0001). CONCLUSIONS: Significant risk factors for failure of total knee arthroplasty were the type of implant, age and gender of the patient, diagnosis, type of fixation, and design of the patellar component. In the ideal situation-treatment of a woman over the age of seventy years who has inflammatory arthritis with a nonmodular, metal-backed tibial component, cement fixation, an all-polyethylene patellar component, and retention of the posterior cruciate ligament-the ten-year survivorship of the prosthesis was estimated to be 98% (95% confidence interval, 97% to 99%).

Adolescent↗
PubMed1992

Adaptative control of above knee electro-hydraulic prosthesis.

Conventional designs of an above-knee prosthesis are based on mechanisms with mechanical properties (such as friction, spring and damping coefficients) that remain constant during changing cadence. These designs are unable to replace natural legs due to the lack of active knee joint control. Since the nonlinear and time-varying dynamic coupling between the thigh and the prosthetic limb is high during swing phase, an adaptive control is employed to control the knee joint motion. Two dimensional simulation indicates that the adaptive controller can improve the appearance of gait pattern. It is adaptable to walking speed and can compensate for the variations of hip moment, hip trajectory and toe-off conditions.

Adaptation, Physiological↗
PubMed2001

Gentamicin PMMA beads and other local antibiotic carriers in two-stage revision of total knee infection: a review.

Local antibiotic carriers are available as resorbable carriers (e.g. gentamicin-loaded collagen) and non resorbable carriers, mostly gentamicin-loaded bone cement in the form of beads or spacers. The release of the antibiotic may differ largely, depending on the properties of the carrier. In the use of spacers the release may remain too low, resulting in subinhibitory gentamicin concentrations. Revision of late deep infection of a knee prosthesis includes extraction, debridement and the use of local and systemic antibiotics. Reimplantation can be performed if healing is appropriate and the bone stock reaches. Otherwise arthrodesis is necessary.

Anti-Bacterial Agents↗
PubMed2004

Early tibial tray failure of a Duracon knee with retrieval analysis.

We report a case of early tibial tray fracture of a Duracon knee prosthesis. Aside from the clinical, radiographic, and gross analysis of the failed prosthesis, we also performed analysis on the retrieved polyethylene component and the fractured tibial baseplate. In the analyses, we noted significant femoral component malalignment, uneven tray cementation, and inherent metallurgical weakness. It appears that the high compressive load on the medial tray resulted in bending fatigue failure. To avoid this complication, it is important to restore the normal alignment of the knee joint and use a polyethylene insert of higher conformity, at least 6 mm thick.

Aged↗
PubMed2001

Contact stress on polyethylene components of a new rotating hinge with a spherical contact surface.

OBJECTIVE: To assess the nonlinear contact stress of a new rotating hinge of our knee prosthesis at various rotation angles. DESIGN: The contact surface between the metal tibial bearing and the ultra-high-molecular weight polyethylene plate of a conventional rotating hinge is of cylindrical design. We have designed a new type of rotating hinge with a congruous spherical contact surface. BACKGROUND: The endoprosthesis for reconstruction of limb after wide resection of malignant tumor around knee usually incorporates a rotating hinge. Our new rotating hinge with a spherical contact surface incorporates the benefits of an increased contact surface and potentially increased rotational stability during axial loading. METHODS: We utilized the ABAQUS finite element program to assess the nonlinear contact stress of this new rotating hinge at rotation angles of 0 degrees, 4 degrees and 8 degrees, based on a contact force of about 2800 N. RESULTS: The results show that von Mises stress for the finite element model of the polyethylene component of this rotating hinge ranges from 4.90 x 10(-6) to 8.22 MPa at the aforementioned rotational angles. The von Mises stress is about 1.31--1.82 MPa on the major parts of the ultra-high-molecular weight polyethylene plate, including both flanks. There is a mild stress concentration on the outer edge of polyethylene component, especially at 4 degrees and 8 degrees of rotation. The maximum values of von Mises stress at the contact surface at 0 degrees, 4 degrees and 8 degrees of rotation are 5.92, 7.49 and 8.22 MPa, respectively. These contact stresses are within the safety range of the ultra-high-molecular weight polyethylene (compressive yield strength, 14 MPa). CONCLUSIONS: This new rotating hinge has an evenly distributed contact stress during axial load because of congruous contact design.

Finite Element Analysis↗
PubMed1994

Failure of a polyethylene total knee component presenting as a thigh mass. Report of a rare complication of total knee arthroplasty.

Early failure caused by wear of the polyethylene bearing surface of a metal-backed tibial platform or a metal-backed patellar component in a total knee prosthesis has been a recognized complication; patients with these problems initially have pain and instability. A patient who had a cystic mass in the distal thigh was evaluated, and osteolysis of the distal femur was detected. Polyethylene debris and reactive synovium were confirmed surgically and histologically, indicating a cause-effect relationship of polyethylene wear debris and failure of the total knee arthroplasty. Regular and long-term patient follow-up evaluation after total joint arthroplasty is essential for the detection of early evidence of occult polyethylene wear.

Aged↗
PubMed1994

Postoperative alignment of total knee replacement. Its effect on survival.

Four hundred twenty-one posterior cruciate condylar total knee arthroplasties were performed between 1975 and 1983. Anatomic alignment of the knee was recorded on follow-up evaluations from two months to 13 years postoperatively. Patients were stratified into a normal group that was 5 degrees to 8 degrees anatomic valgus, a varus group that was from 4 degrees anatomic valgus to any degree of varus, and a valgus group that was more than 9 degrees anatomic valgus. There were eight failures, five in the varus group and three in the normal group. There were no failures in the valgus group. Kaplan-Meier survival curves showed no significant difference between normal and valgus groups; however, there was a statistical difference between the valgus and varus and the normal and varus groups. A surgeon should align a total knee prosthesis in neutral or a slight amount of anatomic valgus to give the patient the best chance for long-term survival.

Aged↗
PubMed1997

Coverage of knee-tumor-resection prostheses with free flaps.

Free latissimus dorsi free flaps were used for the treatment of three patients with malignant tumors localized at the distal end of the femur. In all cases, a knee prosthesis was used after tumor resection. In two patients, the prosthesis was covered with a free latissimus dorsi flap immediately after insertion. In one patient, the exposed prosthesis that was inserted 9 months previously was also covered with a free latissimus dorsi flap. Histopathologic diagnosis of the tumors was osteosarcoma in two cases and fusiform cell sarcoma in one case. Free-tissue transfers were successful in spite of preoperative chemotherapy and/or radiotherapy. Chemotherapy was started 3 weeks postoperatively in all cases. Patients ambulated 6 weeks after surgery and knee functions were satisfactory during a 1 year follow-up.

Adult↗