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 757 records · Page 42Linked to original sources
PubMed1986

Effects of total knee replacement design on femoral-tibial contact conditions.

Ten fresh knee specimens with prosthetic components inserted were tested in a loading rig. Compressive and shear force were applied to the femur with the tibia held fixed. The location of the femoral-tibial contact points was measured. The contact reaction forces, the shear forces, and the rocking moments transmitted to the tibial component were calculated. The variations in the test conditions were: high and low compressive force, flexion angles of 0 degree, 45 degrees, and 90 degrees, three curvatures of tibial plastic inserts, and the posterior cruciate retained or resected. When the posterior cruciate was retained, the contact points were close to the center of the component; for cruciate resection, the contacts were close to the anterior of the component. The shear forces and rocking moments were higher for cruciate resection, but the contact reaction forces were lower. There is a wide variety of knee prosthesis designs, but the amount of inherent stability between the femoral and tibial surfaces, and whether the posterior cruciate ligament is retained or sacrificed, are two of the most important design variables. This study shows that cruciate resection increases the shear forces and the rocking moments to the tibial components and that additional fixation means may be necessary to compensate. On the other hand, cruciate retention with low conformity gives higher contact forces, which may lead to more wear in the long term. Cruciate sacrificing designs with intercondylar guiding surfaces are a separate category of design and were not considered in this study.

Biomechanical Phenomena↗
PubMed1994

Distal loss of femoral bone following total knee arthroplasty. Measurement with visual and computer-processing of roentgenograms and dual-energy x-ray absorptiometry.

The changes in bone-mineral content in the distal aspect of a cadaveric femur that had been prepared for insertion of the femoral component of a total condylar knee prosthesis were evaluated with visual inspection and computer-processing of roentgenograms and with dual-energy x-ray absorptiometry. Seventeen small slices of bone, each three millimeters wide, were removed so that, finally, 89 per cent of the bone was lost from the distal femoral metaphysis. Standardized lateral roentgenograms of the specimen were made with use of a reference step-wedge of hydroxyapatite, and dual-energy x-ray absorptiometry studies were performed with the x-ray beam tangential to the interface. The roentgenograms were digitized and the bone mineral was measured with use of computer analysis. Dual-energy x-ray absorptiometry was performed with and without the femoral prosthesis in place, in order to determine the effect of the metallic prosthesis on the accuracy of the measurement. A bone loss of 25 per cent or more was identified visually by all five of the readers 100 per cent of the time; losses of 20 to 24 per cent, 15 to 19 per cent, 10 to 14 per cent, and 3 to 9 per cent were correctly identified 92, 75, 66, and 59 per cent of the time, respectively. The measurements of bone-mineral content that were obtained from the digitized roentgenograms were linearly correlated with the actual bone-mineral content (the ash content) (r = 0.97, p < 0.001) and were three times more accurate than the visual readings. The determinations of bone-mineral content with dual-energy x-ray absorptiometry correlated highly with the ash content (r = 1.00, p < 0.001) and were seven times more accurate than the visual readings. There was only a 4 per cent difference between the measurements with dual-energy x-ray absorptiometry made with the prosthesis in place and those made without it in place (p < 0.01). Dual-energy x-ray absorptiometry was the most accurate of the three methods and could detect the smallest experimentally created loss; computer-processing and visual-processing of roentgenograms detected losses of 8 per cent or more and 25 per cent or more, respectively. Dual-energy x-ray absorptiometry and computer-processing of the roentgenograms quantified the bone loss, while visual-processing could detect only the presence or absence of bone loss.(ABSTRACT TRUNCATED AT 400 WORDS)

Absorptiometry, Photon↗
PubMed2005

Should we resurface the patella in total knee replacement? Experience with the Nex Gen prothesis.

Patellar resurfacing is a controversial issue in primary total knee replacement. So, we took advantage of a large study to try and answer this question. An open prospective multicentric study was conducted about the outcome of the Nex Gen Total Knee prosthesis with clinical and radiological follow-up at regular intervals (1, 2 and 5 years). The data were centrally collected and analyzed by independent observers. A total of whole 5,915 cases were included (487 in the French group); incidences of patello-femoral pain were observed in both French and international groups and compared between cases with or without resurfaced patellae. Only osteoarthritic cases were selected for this particular study. Statistical analysis was performed using a Pearson's Chi-square test with a 95% confidence interval. The frequency of preoperative pain was significantly higher in the French group; 85.1% versus 66.6% (p<0.05). No patello-femoral pain appeared in preoperatively painless patients in the French group. The frequency of lateral patellar release was similar in both groups. 35.7% of the patellae were resurfaced in the international group versus 98.8% in the French one. At 2 years, patello-femoral pain was observed in 6.3% of cases in the former group versus 0.7% in the latter one. The risk of having patello-femoral pain was 9.45 times higher in the international group. When considering resurfaced cases in both groups the risk of having anterior knee pain was not significantly different (p=0.35). In the French group, one case out of nine (11.1%) with patello-femoral pain had not been resurfaced, while 129 cases out of 151 (85.4%) had not had a resurfacing in the international group. This emphasizes the effect of patellar implant on pain. Although patello-femoral pain is multifactorial, this analysis tool is powerful in getting rid of the "center effect " (cf Swedish register). Even if a longer follow-up for confirmation is needed, our data favor patellar resurfacing with this type of implant in spite of the fact that the trochlear design was considered as anatomical.

Aged↗
PubMed1995

Chronic septic arthritis and osteomyelitis in a prosthetic knee joint due to Clostridium difficile.

A case of chronic septic arthritis and osteomyelitis in a prosthetic knee joint due to Clostridium difficile is reported. A knee prosthesis was installed in a 16-year-old boy for surgical treatment of an osteosarcoma of the femur. Later, the patient suffered a traumatic closed fracture of his patella, and a sterile fluid was aspirated. One month later, the joint displayed inflammation. Culture of the articular fluid yielded a nontoxigenic Clostridium difficile strain. Despite several attempts using conservative medical treatment with penicillins and ornidazole, Clostridium difficile strains with the same antibiotic susceptibility pattern were repeatedly isolated from the joint over an eight-month period. The foreign material was then ablated, and finally, the patient's leg was amputated one year after Clostridium difficile was first isolated. The possible sources of contamination in our case and other reported cases of extraintestinal infection due to Clostridium difficile are discussed.

Adolescent↗
PubMed1992

Tissue reactions at the implant-bone interface of the cementless total knee prostheses with sinking (Okayama University Mark-II type).

Periprosthetic tissues of 14 revised knees of 11 patients, who had undergone Mark-II type cementless total knee prosthesis, were examined to find the relationship between tissue and sinking. Nine patients had rheumatoid arthritis and two had osteoarthritis. Two types of tissue reactions were observed at the implant-bone interface: 1) granulation-dominant tissue, composed of giant cells and macrophages phagocytizing high density polyethylene flakes and dense granules of metal, on the femoral side in six cases, and tibial side in four, 2) fibrosis-dominant tissue on the tibial side in seven, and femoral side in four. On each type, three zones were observed. In the deep zone adjacent to the bone, hyaline cartilage-like tissue was located on the tibial side in four cases, and femoral side in one. An immunohistochemical stain with S-100 proteins and transmission electron microscopy revealed chondrocyte-like features. Chondrogenesis was more frequently observed on the tibial side.

Aged↗
PubMed1999

Relationship between magnitude of resection, complication, and prosthetic survival after prosthetic knee reconstructions for distal femoral tumors.

BACKGROUND AND OBJECTIVES: Limb-sparing surgery has become the preferred surgical treatment of malignant bone tumors. The objective of this study was to evaluate factors that influence the morbidity and outcome of prosthetic knee replacement after resection of malignant tumors of the distal femur. METHODS: Eighty-two patients who had a resection of malignant tumor of the distal femur and implantation of a segmental knee prosthesis (minimum follow-up, 2 years) were retrospectively reviewed. RESULTS: Twenty-nine patients (35%) underwent 32 prosthetic revisions, 6 from perioperative wound complications, 13 from aseptic loosening, and 13 from other complications. The 3-, 5-, and 10-year Kaplan-Meier prosthetic survival rates were 82%, 71%, and 50%, respectively. On univariate analysis, patients who had more than 40% resection of the distal femur (P = 0.010) and those who had all their vasti muscles resected (P = 0.011) had significantly worse prosthetic survivals than the others. On multivariate analysis, resection of more than 40% of the distal femur was a significant negative prognostic factor for prosthetic survival (P = 0.017). Aseptic loosening was the primary cause of late prosthetic failure. Differences in the magnitude of resection influenced prosthetic survivorship more than prosthetic design. CONCLUSIONS: In the distal femoral endoprosthetic replacement, higher short- and long-term complications were found after extensive resections. Aseptic loosening was the primary cause of prosthetic failure.

Adolescent↗
PubMed1999

Effect of prosthetic titanium wear debris on mitogen-induced monocyte and lymphoid activation.

Wear debris generated by joint implant components has been reported to activate inflammatory and immune cells. Particulate debris derived from prosthetic material induces monocytes/macrophages, lymphocytes, synoviocytes, and fibroblasts to secrete cellular products, such as cytokines, which mediate inflammation. It has been speculated that degradation products impair the ability of inflammatory and immune cells to mount a protective response against noxious agents and infectious organisms by interfering with cell activation. Recent in vitro studies suggest that soluble metal ions inhibit T and B cell activation, but it is not known whether insoluble metal particles generated by prosthetic wear in tissue have the same effect. The purpose of the present study was to determine whether titanium wear debris retrieved from periprosthetic tissues surrounding a failed knee prosthesis suppresses activation of human monocytic and lymphoid cells. Peripheral blood monocytes and lymphocytes were incubated with the nonspecific activator pokeweed mitogen (PWM) in the presence or absence of titanium particles. Cell proliferative capacity and production of interleukins IL-1beta and IL-2 were determined as measures of activation. Titanium wear debris induced monocyte secretion of IL-1beta at levels comparable to those induced by PWM alone. In combination with PWM, titanium wear debris stimulated monocytes to secrete higher concentrations of IL-1beta than is stimulated by titanium itself or by PWM alone. Titanium wear debris did not activate lymphocytes, as indicated by marginal changes in DNA synthesis and IL-2 secretion, nor did it suppress the PWM-induced stimulation of DNA synthesis and IL-2 secretion. Our study suggests that nonspecific mitogen activators in spite of exposure to titanium wear debris can stimulate monocytic and lymphoid cells.

Biocompatible Materials↗
PubMed2004

Clinical and functional comparison of bicondylar sledge prostheses retaining all ligaments and constrained total knee replacement.

OBJECTIVE: Comparison of different total knee replacements regarding clinical and functional differences with respect to gait and electromyographic analyses. DESIGN: Retrospective, comparative, clinical and functional study. METHODS: Three groups (control group of 11 healthy subjects, 15 patients with bicondylar sledge prostheses retaining all ligaments (cemented unicondylar prostheses in both the medial and lateral compartment), 15 patients with constrained total knee replacement sacrificing all cruciate and collateral ligaments (cemented total knee prosthesis with intramedullary stems and a large intercondylar tibial post) were compared by clinical evaluation using a number of clinical evaluation scores, a pain scale, surface electromyographic examinations of the lower limb, and gait analysis. RESULTS: Clinical scores revealed significantly worse results for patients with constrained prostheses. Both patient groups had significantly lower clinical scores compared to the control group. Gait analysis and electromyographic parameters revealed no significant differences between both patient groups. Compared to the control group, patients revealed significantly impaired parameters. Electromyography also demonstrated significant differences between patients and controls: mean electromyographic activities were reduced in vastus medialis and lateralis, semitendinosus, tibialis anterior and gastrocnemius. Peak activities were reduced in all muscles but rectus femoris. CONCLUSION: Clinical scores demonstrated significantly better results in bicondylar sledge than in constrained prostheses. Nevertheless, gait and electromyographic analyses did not reveal significant differences. RELEVANCE: Retaining of ligaments in bicondylar sledge prostheses apparently improved the activities of daily living but is not reflected in gait and electromyographic parameters.

Arthroplasty, Replacement, Knee↗
PubMed2006

[Wear particles: key to aseptic prosthetic loosening?].

The aseptic prosthetic loosening of hip and knee prosthesis is the most important cause of implant insufficiency. Bone loss as a result of the biological effect of wear particles is the main cause of such loosening. Wear particles develop their biological activity along different cellular pathways, above all via macrophages, foreign body giant cells as well as fibroblasts of the periprosthetic membrane. These cells induce particle-dependent bone resorption by means of proinflammatory cytokines, such as IL-1beta, TNF-alpha, IL-6 and PGE2. These factors induce the activation of osteoclasts as well as the suppression of osteoblasts. Neutrophil granulocytes and lymphocytes do not play an important role in the process of aseptic loosening. The different wear particles, such as ultra-high molecular weight polyethylene, metal particles, ceramic particles and polymethylmethacrylate can be morphologically recognized very easily. From the clinical point of view, the differentiation between acute or chronic implant infection and particle induced prosthetic loosening is very important, with the histomorphological differential diagnosis between septic and aseptic loosening and their combination being the key clinicopathological factor.

Arthroplasty, Replacement, Hip↗
PubMed1999

Failure of partial cementation to achieve implant stability and bone ingrowth: a long-term roentgen stereophotogrammetric study of tibial components.

Thirty patients with gonarthrosis were operated on with the PCA primary total knee prosthesis and had the tibial component fixed to the bone by partial cementation. In the first two groups of patients, cementation was by a peripheral rim of high and low-viscosity cement, respectively. In the third group, the pegs were cemented with the low-viscosity cement. Follow-up was performed with use of clinical parameters and roentgen stereophotogrammetric analysis. Clinically, the series was successful apart from a problem with tibial component wear, necessitating revision in five patients. At 8 years, the mean Hospital for Special Surgery score was 81 points. Venn-diagram scores revealed four failures and three acceptable cases; the remaining cases were satisfactory. Apart from one loose patellar component, there was no mechanical loosening. Roentgen stereophotogrammetric analysis showed that the tibial components moved relative to the bone; this indicated fibrous tissue fixation, which was corroborated histologically in two patients. The objective, to achieve bone ingrowth, was thus not successfully met. Radiolucent lines were consistently seen, and their size correlated with the migration as measured by roentgen stereophotogrammetric analysis. Furthermore, five continuously migrating prostheses showed significantly larger radiolucent zones than the prostheses that migrated only initially, and they were less well bonded to the bone at 1 year. In conclusion, partial cementation does not appear to be a way to achieve bone ingrowth in porous-coated implants under load.

Aged↗
PubMed2001

[Significance and incidence of type II heparin-induced thrombocytopenia. A prospective study].

AIM: The incidence of heparin-induced thrombocytopenia (HIT type II) as a consequence of postoperative thrombosis prophylaxis after hip or knee prosthesis was investigated in this study. Furthermore the platelets count was postoperatively analysed in patients without HIT II. PATIENTS AND METHODS: Patients with knee and hip prosthesis were included in a prospective study during an 8 months period. All patients received 3 x 5,000 Liquemin (Hoffmann-LaRoche) from the day of the operation until discharge. In cases with a platelet count drop of more than 40% and in patients with clinically manifest thrombosis or embolism a HIT type II test was initiated. RESULTS: 5 of 252 patients included in this study developed a HIT type II. The platelet count drop was on average 65.7% (40.9-81.6). One patient died of a lung embolism (lethality 20%). Four patients were treated with Hirudin and 1 patient with Danaproid-Natrium. There was no drop of the platelet count between the 5th and 7th postoperative day of more than 15% in the other patients without HIT type II. CONCLUSION: In operative departments not enough attention is paid to HIT type II. Knowing the risks with an appropriate monitoring HIT type II can be early detected. Under these conditions the advantages of a heparin prophylaxis outweigh the risk of developing a HIT type II with it's life threatening sequelae.

Aged↗
PubMed1992

The effects of implant design on range of motion after total knee arthroplasty. Total condylar versus posterior stabilized total condylar designs.

Range of motion (ROM) after total knee arthroplasty (TKA) is an important variable in determining clinical outcome. Recent design modifications have been aimed at improving final motion. The posterior stabilized total knee prosthesis was introduced as a modification of the total condylar design, changing the center of curvature of the femoral component to allow greater ROM. In this study, all primary TKAs performed at the authors' institution from July 1982 until December 1986 were reviewed to determine the effect of this design modification on outcome. A total condylar (TC) group comprised 51 arthroplasties and was compared to 53 arthroplasties in a posterior stabilized (PSTC) group. the postoperative protocol was identical in both groups. The mean postoperative flexion was 11 better in the PSTC group; however, the mean preoperative flexion had initially been 10 degrees better in the PSTC group. The maximum flexion achieved by any patient in both groups was similar, but the TC group actually gained slightly more arc of motion. The better motion in the PSTC group may be secondary to better motion preoperatively and not implant design in this series. The more limited the preoperative ROM, the greater the quadriceps stiffness is likely to be, which is an important determinant of postoperative flexion. Review of the literature supports present observations that a group with less mean preoperative motion paradoxically gains a slightly greater increment of flexion. Differences in flexion after TKA are difficult to attribute to design in either the current study or by a review of the literature. This is because determinants of flexion after TKA are multifactorial and outcome data limited, notwithstanding the similarities among modern prostheses.

Adult↗
PubMed1995

[Cinematic in vivo analysis of the knee: a comparative study of 4 types of total knee prostheses].

PURPOSE OF THE STUDY: The goal of the study was to assess in vivo kinematics for four designs of knee prosthesis during level walking, stair climbing and non weight-bearing flexion-extension. PATIENT AND METHODS: 19 patients with unilateral total knee arthroplasty (TKA) were included [5 bicruciate sparing prosthesis (BI), 5 posterior cruciate sparing prosthesis with flat tibial polyethylene (PP), 5 posterior cruciate sparing prosthesis with congruent tibial polyethylene (PC), 4 postero stabilised (PS)]. These 19 patients had no prosthesis nor pathological situation in any other joint of the lower limbs. Each of these 19 prosthesis had an HSS score greater than 80 and no radiographic signs of loosening. Magnitudes of the knee rotations (flexion-extension axial rotation valgus-varus) were evaluated with a 6 degrees freedom of motion electromagnetic-goniometer during level walking, stair climbing and non weight-bearing flexion-extension. The magnitudes of the three rotations were recorded for the 19 prosthetic knees and for the 19 controlateral non prosthetic knees of the patients. Reproducibility of the method was also evaluated on 12 healthy subjects by comparison of magnitudes observed during two different recordings. RESULTS: Reproducibility was excellent for magnitudes of flexion (r = 0.95/p = 0.0001) and axial rotation (r = 0.55/p = 0.002) but less satisfactory for valgus-varus movements (r = 0.46/p = 0.005). The magnitudes of the three rotations were inferior for TKA in comparison with healthy knees for any activities. By comparison of the 19 prosthetic and non prosthetic knees we recorded smaller magnitudes of axial rotation during swing phase for level and stair climbing and during non weight-bearing flexion extension movements. Between the four kind of prosthesis we observed: greater magnitudes of flexion for BI and PC prosthesis during stair climbing (p < 0.05) and greater magnitudes of flexion for BI PC and PS prosthesis during stair descending (p < 0.05). PC prosthesis instead of a congruent polyethylene tibial plateau had greater magnitudes of axial rotation than non constrained BI prosthesis during stair climbing (p = 0.009). In spite of a high femoro-tibial congruency we recorded axial rotation in PS prosthesis during each activities. DISCUSSION AND CONCLUSION: Our method evaluating in vivo knee kinematics was reproducible. These four knee prosthetic designs in spite of a good functional results were unable to reproduce magnitudes of movements recorded in healthy subjects. The small number of prosthesis included in the study prompt us to consider as no definitive the differences observed between the 4 designs. Anyway the influence of design on kinematics should be considered as relative since we recorded axial rotation for all four cruciate substituting prostheses although they had high femoro-tibial congruency. Influence of femoro-tibial congruency and cruciate ligament sparing could be assessed in vivo by means of this reproducible method on a larger population.

Adult↗
PubMedDate not supplied

[Computer assisted production of individual anatomic endoprostheses].

Long-term anchorage of foreign material in vital bone has proven to be the main problem in endoprosthetics. In the authors opinion, modelling of an individual anatomic anchorange component is, at present, the best way to transmit stresses harmoniously in order to utilize functional adaptation of bone and to attain long-term function. The production of a true-to-scale joint model is possible with computer-assisted-tomography. This model of a joint surface or bone canal can be used to construct an individual endoprosthesis prior to surgery. Our procedure of manifactoring a hip stem and a knee-surface-prosthesis is described.

Computers↗
PubMed2006

Efficacy of periarticular multimodal drug injection in total knee arthroplasty. A randomized trial.

BACKGROUND: Postoperative analgesia with the use of parenteral opioids or epidural analgesia can be associated with troublesome side effects. Good perioperative analgesia facilitates rehabilitation, improves patient satisfaction, and may reduce the hospital stay. We investigated the analgesic effect of locally injected drugs around a total knee prosthesis. METHODS: Sixty-four patients undergoing total knee arthroplasty were randomized either to receive a periarticular intraoperative injection containing ropivacaine, ketorolac, epimorphine, and epinephrine or to receive no injection. The perioperative analgesic regimen was standardized. All patients in both groups received patient-controlled analgesia for twenty-four hours after the surgery, and this was followed by standard analgesia. Visual analog scores for pain, during activity and at rest, and for patient satisfaction were recorded preoperatively and postoperatively and at the six-week follow-up examination. The consumption of patient-controlled analgesia at specific postoperative time-points and the overall analgesic requirement were measured. RESULTS: The patients who had received the injection used significantly less patient-controlled analgesia at six hours, at twelve hours, and over the first twenty-four hours after the surgery. In addition, they had higher visual analog scores for patient satisfaction and lower visual analog scores for pain during activity in the post-anesthetic-care unit and four hours after the operation. No cardiac or central nervous system toxicity was observed. CONCLUSIONS: Intraoperative periarticular injection with multimodal drugs can significantly reduce the requirements for patient-controlled analgesia and improve patient satisfaction, with no apparent risks, following total knee arthroplasty.

Aged↗
PubMed1981

Technical note--tilting stubbies.

Bilateral amputees who are fitted with standard full length prostheses find it difficult to walk fast or climb up and down stairs. Usually stubbies, or short prostheses with non-articulated rocker bottoms, are also provided, especially for geriatric amputees. An interchangeable system has been evolved which enables the same prosthesis to be used either as a full length prosthesis or as a stubby. An above-knee prosthesis is converted into a stubby by removing the shin and foot piece from the socket/knee unit and replacing it with an articulated hollow rocker. The tilting of the socket/knee unit which is made possible by the articulation at the junction of the rocker and socket enables the amputee to lower his body to use Indian type toilets with the help of a low level folding portable commode, in addition, tilting helps the amputee to work outdoors in gardens and fields. The interchangeable system is particularly suitable for bilateral amputees in developing countries.

Amputation, Surgical↗