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At least 109 records · Page 6Linked to original sources

PubMed1997

[Evaluation of the predictive value of fibrin degradation products in the detection of deep venous thrombosis after total knee prosthesis].

The total knee arthroplasty (TKA) favours deep venous thrombosis (DVT), more often sural thrombosis. In this case, pulmonary embolism is exceptional but sural thrombosis can give a poor functional prognostic by trophic disorders. The purpose of this work is to verify the predictive value of D-Dimer by Elisa technic in the detection of DVT after TKA. We have studied 42 TKA at the Edouard HERRIOT Hospital(Lyon) between April 2, 1992 and October 20, 1994. Patients were divided in two groups: with DVT (n = 5) and without DVT (n = 37). Prophylactic heparinotherapy was systematic. The biologic follow-up by ELISA technic(Fibrinostika FbDP, Organon Teknika) of the D-Dimer were realized at D0 (Day 0) preoperative period and D1, D4, and D6 postoperative period. An echo-Doppler exam were effected at D8 postoperative. The analysis of mean rate of the D-Dimer didn't show significative difference between the two groups at D0, D1, D4 and D6. But, we observed that the rate of D-Dimer increased after TKA significantly in both groups. We can't evaluate predictive interest of the D-Dimer after TKA but the little number of DVT authorizes to pursue this study and to moderate our conclusion.

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PubMed2004

The Oxford unicompartmental knee prosthesis: a 2-14 year follow-up.

Our medium- and long-term results obtained with the Oxford unicompartmental knee prosthesis for unicompartmental knee osteoarthrosis are presented. Ninety-seven prostheses were evaluated (87 medial, 10 lateral) in 86 patients, with the Hospital for Special Surgery knee score after 2-14 years (mean follow-up: 6 years 9 months). Five prostheses were lost to follow-up. Eight patients died, not related to surgery; none had undergone a revision. Fourteen revisions (of which one bilateral UKP), 11 medial and three lateral, were performed. The mean HSS score of the 69 UKPs was 178.8 (80% excellent, 10% good, 4% fair, 6% poor). These findings confirm the good results reported in other studies, regarding proper patient selection and a consistent operative technique.

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PubMed1976

A new total knee prosthesis: the "total-condylar".

We have described the instrumentation and surgical technique of a new total knee prosthesis, the Total-Condylar, designed at the Hospital for Special Surgery (New York) and which we are the first to use in Italy. This prosthesis has evolved from the "sliding" prosthesis and seems to us to constitute a real step forward. The femoro-patellar compartment is completely substituted. The cruciate ligaments are removed, which markedly increases the possibility of correcting even severe deformities. The fixation of the tibial component is improved by the adoption of a short stem. The prosthesis has a certain intrinsic stability on weightbearing. The surgical technique is characterised by bone sections perpendicular to each other by the use of aligning instruments which simplify the operation. Our experience is just beginning (five cases) but our results so far are very encouraging and correspond to those reported in a very much larger series in the United States.

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PubMed1999

Measurement of bone mineral density by dual-energy X-ray absorptiometry around an uncemented knee prosthesis.

Dual-energy x-ray absorptiometry allows the measurement of bone mineral density (BMD) around an uncemented hip prosthesis, but has not so far been widely used to measure BMD around a knee prosthesis. We studied 16 patients undergoing total knee replacement using a Miller-Galante uncemented prosthesis for either osteoarthritis or rheumatoid arthritis of the knee. The precision of the measurement was improved by using a leg brace. The pattern of bone loss differed in the lateral projection by region (P = .001). There was significant loss of bone from the distal femur but not from the patella or proximal tibia over the 6-month period after insertion of a knee prosthesis.

Absorptiometry, Photon↗

PubMed1992

Development of an above-knee prosthesis equipped with a microcomputer-controlled knee joint: first test results.

The shortcomings of conventional above-knee prostheses are due to their lack of adaptive control. Implementation of a microcomputer controlling the knee joint in a passive way has been suggested to enhance the patient's gait comfort, safety and cosmesis. This approach was used in the design of a new prosthetic system for the above-knee amputee, and tested on one patient. The knee joint of a conventional, modular prosthesis was replaced by a knee joint mechanism, equipped with a controllable brake on the knee joint axis. Sensors and a microcomputer were added, keeping the system self-contained. The modularity of the design permits the use of an alternative, external, PC-based control unit, emulating the self-contained one, and offering extended data monitoring and storage facilities. For both units an operating environment was written, including sensor/actuator interfacing and the implementation of a real-time interrupt, executing the control algorithm. A double finite state approach was used in the design of the control algorithm. On a higher level, the mode identification algorithm reveals the patient's intent. Within a specific mode (lower level), the relevant mode control algorithm looks for the current phase within the gait cycle. Within a particular phase, a specific simple control action with the brake replaces normal knee muscle activity. Tests were carried out with one prosthetic patient using a basic control algorithm for level walking, allowing controlled knee flexion during stance phase. The technical feasibility of such a concept is illustrated by the test results, even though only flexion during early stance phase was controlled during the trials.(ABSTRACT TRUNCATED AT 250 WORDS)

Artificial Limbs↗

PubMed1995

Tuberculous and foreign-body granulomatous reactions involving a total knee prosthesis.

This case report describes loosening of a right knee prosthesis and represents the first report of the simultaneous occurrence of 2 granulomatous processes involving a prosthetic joint. Microscopic examination of the tissue revealed areas of foreign-body granulomas and areas of necrotizing granulomas and caseation. Acid-fast bacilli cultures were positive for Mycobacterium tuberculosis. The pathophysiology of implant loosening following an inflammatory reaction to components of prosthetic materials is discussed. Also discussed is the occurrence of infectious complications and rarity of tuberculous infections associated with prosthetic implants.

Aged↗

PubMed1977

Herbert total knee prosthesis: combined laboratory and clinical assessment.

We tested the Herbert knee prosthesis, which was designed to restore intrinsic stability with limited degrees of freedom for rotation to severely damaged or deformed knees, in a knee simulator. These tests indicated a tendency for the prosthesis to fracture through the medial femoral housing after cycling for the equivalent of one to three years of normal use. In a clinical series of thirty-five knees treated with the prosthesis, there were five failures similar to those produced by laboratory testing. On the basis of this combined study, the Herbert prosthesis appears to have design characteristics that seriously limit its usefulness for long-term knee replacement. Testing in a knee simulator in this case appeared to be a valid predictor of clinical failure.

Biomechanical Phenomena↗

PubMed1995

The posterior stabilized total knee prosthesis. Assessment of polyethylene damage and osteolysis after a ten-year-minimum follow-up.

The long-term results of use of the posterior stabilized total knee prosthesis were evaluated with regard to clinical performance, survival of the implant, polyethylene wear, osteolysis, and loosening. One hundred and twenty patients had 165 primary total knee arthroplasties, with insertion of a posterior stabilized total knee prosthesis with a metal-backed tibial component with cement, between March 1981 and March 1983. Thirty-seven patients (fifty-three knees) subsequently died, five patients (six knees) were lost to follow-up, three patients (three knees) refused evaluation, and one patient (two knees) was excluded because of severe medical debilitation. Thus, seventy-four patients (101 knees) were available for analysis. The mean age of the patients at the time of the operation was sixty-four years (range, twenty-two to eighty-one years). The mean duration of follow-up was ten years and eight months (range, ten years to eleven years and ten months). Preoperatively, the mean arc of motion was 94 degrees (range, 65 to 130 degrees), compared with 110 degrees (range, 90 to 145 degrees) at the latest follow-up examination. The mean knee score, according to the rating system of The Hospital for Special Surgery, was 51 points (range, 18 to 73 points) preoperatively, compared with 85 points (range, 0 to 100 points) at the latest follow-up examination. When the four knees that had a revision are excluded, the mean knee score, according to the rating system of the Knee Society, was 92 points (range, 67 to 100 points) and the mean functional score was 71 points (range, 0 to 100 points) at the latest follow-up examination.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1995

Optimal control for an above-knee prosthesis with two degrees of freedom.

Our previous research and clinical tests of a self-contained powered above-knee prosthesis (AKP) showed that a knee joint with one degree of freedom (DOF) increases the energy cost of walking with respect to able-bodied subjects. Better symmetry of the gait can improve performance, so we suggest here the integration of a second powered DOF into the knee joint mechanism to control the internal-external rotation of the shank-foot complex. The control for the AKP with two DOFs is based on a method of optimal tracking. The data used for analysis were collected in able-bodied subjects braced with an ankle splint to experimentally duplicate a gait like that of amputees using a two-DOF prosthesis. The simulation showed the following: (1) the technique of optimal programming can be used for simulation of the artificial leg during locomotion; (2) the optimal tracking method is an efficient tool for selection of actuators for the above-knee prosthesis, ensuring that the tracking remains within limits. Limitation of joint torque is desirable in order to reduce the size of the motor, but beyond a certain point limiting maximal torques lead to tracking errors that are associated with higher energy costs and hence the need for a larger power source. The errors are also associated with higher forces at the interface between the socket and the prosthesis. The optimal tracking method allows the optimization of tracking with constraints on the size of the motor used and its energy cost.

Adult↗

PubMedDate not supplied

[Treatment of necrosis of the femur condyle with a medial gliding knee prosthesis].

Spontaneous osteonecrosis of the femoral condyles occurs rather seldom particularly in elderly patients. Whereas some authors recommend valgusosteotomy and bone drilling, implantation of a unilateral knee prosthesis should be performed in the presence of large defects. It is reported a series of 11 patients suffering from osteonecrosis of the femoral condyle. All patients were treated by a unilateral knee prosthesis with good results except one case. The filling of the defect with cancellous bone prior to the implantation of the condylar part of the prosthesis is mandatory.

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PubMed2003

[The hinged knee prosthesis: outdated design or valuable implant for difficult cases?].

There are excellent results after unconstraint or semiconstraint bi- or tricompartimental total knee arthroplasty in case of uncomplicated degenerative joint disease of the knee. In the Swedish knee study, cumulative survival of unconstraint or semiconstraint knee prostheses was about 90 % at 10 years. In studies of single institutions, survival rates of more than 90 % at 15 years are reported. However, there is a need of more constraint designs because of the increasing number of complex total knee arthroplasties with disrupted collateral ligaments, deformities with flexion extension gap imbalance, comminuted distal femur fracture, distal femoral non-union in elderly patients and revision with massive bone loss. Initial hinged total knee designs were associated with a high failure rate. More recent designs have improved the femorotibial articulation and reduced the polyethylene wear. The bone resection necessary in actual hinged designs is similar to the resection in modern condylar prostheses. Due to these improvements, long-term survival of the best hinged designs are similar to the best condylar designs. In our study of a consecutive series of 422 hinged Blauth prostheses, the cumulative survival of the prostheses was 94.4 % at 20 years. Therefore, the hinged knee prosthesis is a valuable implant in case of complex total knee arthroplasty.

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PubMed1996

[Influence of the tibial slope on tibial translation and mobility of non-constrained total knee prosthesis].

PURPOSE OF THE STUDY: We determined retrospectively the influence of posterior tibial slope and anterior cruciate ligament (ACL) sparing on anterior tibial translation in 68 Cloutier total knee prosthesis. We also precised the influence of posterior tibial slope on knee functional score and appearance of tibial prosthetic interfaces. MATERIAL: 38 Cloutier total knee prosthesis (62 patients mean aged 62 +/- 10 years (36-76) at surgery) reviewed at systematic follow-up control, after a mean period of 5.5 +/- 3 years (2-15), were included in the study. The ACL was preserved in 38 knees and sacrified in 30 knees, the posterior cruciate ligament was preserved in all cases. The prosthetic design was the same whatever the number of cruciate ligament preserved. Osteoarthritis was the reason for surgery in 54 knees, and rheumatoid arthritis in 14 knees. Mean HSS knee score was 54 +/- 10 (29-80) before surgery and 89 +/- 10 (35-100) at follow-up. The mean range of motion was 103 +/- 24 degrees (30-130) before surgery and 110 +/- 14 degrees at follow-up (40-130). METHODS: Anterior tibial translation was determined on two profil x-rays (non weight bearing and weight bearing) at 20 degrees of flexion by comparing the position of tibial tray with regard to posterior edge of femoral prosthesis. Tibial slope was measured on lateral view with regard to peroneus axis. Appearance of tibial prosthetic interface was studied in 48 knees on AP and lateral x-rays orientated with an image intensifier in order to obtain the x-ray would be parallel to the tibial interface. RESULTS: Posterior tibial slope (mean value 6.2 degrees +/- 4.2 degrees) was the main factor influencing the anterior tibial translation (mean value 3.9 +/- 4.6 mm) (p = 0.0007). A 10 degree increase of posterior tibial slope makes the anterior tibial translation rise by 5.6 mm in weight bearing situation. When ACL was preserved, the anterior tibial translation was lower but the decrease was not significant. Likewise, preservation of ACL or the degree of posterior tibial slope had no influence on: 1) HSS knee functional score, 2) range of motion. Radiolucent lines were observed in 18 out of 48 knees, but their occurrence was not influenced by the degree of posterior tibial slope or preservation of ACL. DISCUSSION: Posterior tibial slope has a higher influence than ACL preservation on anterior tibial translation. The increase of posterior tibial slope in order to improve range of motion and to protect the bone-prosthetic tibial interface appeared unjustified with this non-constrained prosthesis. Moreover, implantation of tibial tray (whatever the preservation of ACL) with an important posterior inclination exposes to high anterior tibial translation in weight bearing situation. This last condition could reduce the survivorship of tibial polyethylene.

Adult↗

PubMedDate not supplied

[Biomechanical study of the Oxford knee prosthesis with mobile meniscus].

Polyethylene meniscal bearing of the Oxford knee produce conforming surfaces and are free to move with knee movements. We studied polyethylene wear of 23 meniscal bearings implanted after a mean time of 38 months. The mean penetration rate of the polyethylene was 0.026 mm per year, statistically correlated with implanted time. The large areas of contact provided by such design are able to reduce polyethylene wear in knee prosthesis at levels smaller to those reported for hip. We also studied bearing movement on six cadaveric specimens fixed in a six degrees of freedom rig. The movements take place in both compartments of the knee in the same direction as for normal menisci during flexion-extension and rotation. Unicompartmental arthroplasty using meniscal bearing knee can restore such movements when the anterior cruciate ligament is present.

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PubMed2001

[Infection of a total knee prosthesis revealed by an abscess of the posterior leg compartment. A case report].

We report a case of infection of a non-cemented total knee prosthesis that led to abscess formation in the posterior compartment of the leg. This case illustrates the deleterious effect of screws used to fix the non-cemented articular surface of the tibia. Infection, like osteolysis due to polyethylene granuloma, can develop along the screw tract and reach the posterior compartment, especially when the screw protrudes through the posterior cortical of the tibia. Diffusion of an intra-articular event into the posterior compartment should be suspected in patients with a total knee prosthesis who experience calf pain.

Abscess↗

PubMed1975

A voluntarily controlled electrohydraulic above-knee prosthesis.

Most above-knee amputees to date are using prostheses employing either constant friction or some type of programed hydraulic damping which the wearer has no control over and which limits his gait speeds. A new system was designed and tested in which voluntary control of a lower-limb prosthesis is derived from the EMG signals of residual thigh muscles in the stump. These signals, after suitable conditioning, open or close solenoid valves, which form a closed hydraulic loop around the damping cylinder in the knee joint. Thus, the amputee is able to voluntarily vary the resistance to knee flexion, from free swing to full lock, by operating valves controlling the resistance to flow around a hydraulic cylinder. The main advantages of this system are a variable and more aesthetic gait, stability over uneven terrain, and because the lock prevents only knee flexion, the amputee can rise on his prosthesis and so use a passive appendage as an active element of his skeleton. The results of this project demonstrate that the concept of an EMG voluntarily controlled hydraulic prosthesis is viable; however, continuing effort is required to make this system lighter, more compact, and cosmetically acceptable.

Biomechanical Phenomena↗

PubMed1988

An evaluation of the mechanical failure modalities of a rotating hinge knee prosthesis.

The clinical and metallurgical performance of 12 retrieved Noiles total knee prostheses was investigated. Clinical histories and serial roentgenograms were used in conjunction with the American Society for Testing and Materials (ASTM) standard implant retrieval and analysis techniques to assess device performance. All of the devices were removed because of implant loosening with pain, while two devices also had a late infection. The average time in situ for all devices was four years. Roentgenographically, all of the devices showed signs of progressive radiolucencies. Ten (83%) of the devices migrated proximally within the femur. A marked varus drift was observed in eight (67%) of the retrieved prostheses. Hypertrophy of the femoral cortex was observed in eight (67%) of the cases. Seventy-three percent of the polyethylene tibial stems exhibited extensive wear on the anterior and medial aspects of the articulating surface. Extensive wear was also seen on the anterior and extreme posterior aspects in 92% of the polyethylene tibial plateau bearings. This wear was a consequence of the migration of the femoral component leading to buttressing of the plastic components against bone or bone cement. This study indicates serious design flaws in the Noiles knee prosthesis that unless corrected would question the use of the device in either primary or revision knee surgery.

Adult↗

PubMed1979

The total condylar knee prosthesis. A report of two hundred and twenty cases.

The total condylar knee prosthesis is a non-hinged surface replacement which can be used for almost all knee deformities. This report discusses the first consecutive 220 arthroplasties in 183 patients. Follow-up time was three to five years. Before operation eighty-six knees had more than 10 degrees of fixed varus deformity and thirty-one knees had more than 10 degrees of fixed valgus deformity. All patients were assessed using The Hospital for Special Surgery scoring system. Of the total of 220 knees, 137 (62%) were rated excellent; sixty-one (28%), good; ten (4.5%), fair; and twelve (5.5%), poor. Of 139 osteoarthritic knees, 93% were rated excellent or good. Complications included three deep infections and four cases of posterior subluxation. The over-all reoperation rate was 3.6%.

Arthritis, Rheumatoid↗

PubMed1992

SEM and chemical micro-analysis in a failed total knee prosthesis.

Authors performed SEM and EDS analyses in a cemented removed knee prosthesis demonstrating the average values of mineral elements in the bone surrounding the prosthesis. The composition of the metallic prosthesis surface in different microareas was also studied.

Alloys↗