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PubMed1991

Survivorship analysis of the uncemented porous-coated anatomic knee replacement.

Ninety-six patients who had a total of 108 replacements with an uncemented porous-coated anatomic knee prosthesis were followed for an average of sixty-four months (range, thirty-nine to ninety-three months). At the time of the most recent follow-up, twenty-one implants (19 per cent) had failed, all due to problems with the tibial component. A patellar component was not used, and no noteworthy patellar problems were encountered after the operation. There were no infections about the prostheses, and no femoral implant was revised. The most common cause of failure was collapse of the anteromedial part of the tibial plateau, which occurred in fourteen knees. The prosthesis loosened without collapse of bone in two knees, and five knees were revised because of gross wear of the polyethylene. When the time of failure was defined as the point at which revision of the prosthesis was recommended, the cumulative rate of survival was 84 per cent (95 per cent confidence interval, +/- 7 per cent) at five years and 77 +/- 10 per cent at six years. When the time of failure was defined as the point at which the knee replacement was actually done, the five-year rate of survival was the same. No significant differences were demonstrated between groups that were stratified by age, sex, weight, or primary diagnosis. We therefore do not recommend the use of an uncemented porous-coated anatomic knee replacement of the design that was evaluated in this study.

Adult↗
PubMed2005

Serratia marcescens prosthesis infection successfully treated with meropenem after imipenem failure.

A 78-year-old woman developed an early knee-prosthesis infection due to multiresistant Serratia marcescens that was successfully treated with high-dose meropenem, after failure of a long-term therapy combining imipenem and multiple surgical interventions. Because of its lower neurotoxicity, meropenem might be preferred to imipenem/cilastatin for the treatment of osteo-articular infections due to multiresistant Gram-negative bacilli in the elderly.

Aged↗
PubMed1993

[Knee arthroplasty with total condylar endoprosthesis].

Authors report on experiences gained with the Total Condylar knee prosthesis, representing the third generation in the development of the knee endoprosthesis. Based on results of 17 operations it is stressed that after the implantation in the severely degenerated or destroyed knee joint they succeeded to reach a significant decrease of pain and increase of the range of movement. After the implantation of the prosthesis adequate stability can be gained in knee joints without cruciate ligaments.

Adult↗
PubMedDate not supplied

Anametric total knee arthroplasty.

The early experience with the anametric knee prosthesis shows it to be effective in achieving the aims desired in total knee arthroplasty. Decreased pain and improved function have been noted in most patients, with relatively few complications. In osteoarthritics, patellar replacement increases the level of improvement. This prosthetic system has been improved by the addition of further sizes and additional tibial fixation options. Detailed long-term follow-up evaluation of these patients will be necessary to judge the effectiveness of the newly introduced design modifications.

Adult↗
PubMed2004

The precision and accuracy of templating the size of unicondylar knee arthroplasty.

In trauma and joint arthroplasty, preoperative templating is an important step that can help in the selection of implant size, position and alignment. Although the precision (reproducibility) of templating in unicondylar knee arthroplasty has been assessed previously, the accuracy has never been studied. Our aim is to assess the precision and accuracy of using the templating system for one commonly used unicondylar knee arthroplasty, ALPHANORM design (Alphanorm Medizintechnik, Germany). Eight observers used the templating system to estimate the size of the unicondylar knee prosthesis ALPHANORM in 29 randomly selected patients with osteoarthritis. The observers, who all were orthopaedic surgeons with two different levels of experience, worked independently and repeated their measurements 2 weeks later. All the patients subsequently underwent unicondylar knee replacements, and the actual size of the femur and tibia was assessed intra-operatively without any knowledge of the template sizes. Our results revealed a high level of intra-observer reproducibility. However, the inter-observer reproducibility and the accuracy all were poor.

Arthroplasty, Replacement, Knee↗
PubMed1995

Periprosthetic bone mineral density of the distal femur after total knee arthroplasty.

Evaluation of the bone mineral density (BMD) was performed in the distal femur around the femoral component of a total knee prosthesis. A total of 48 females were enrolled for this study, including 14 with osteoarthritis of one knee undergoing total knee arthroplasty (TKA) with an Osteonics prosthesis, 14 with osteoarthritis of one knee undergoing TKA with a Whiteside prosthesis, and 20 age-matched normal controls. The BMDs of both knees were measured before operation, and then at 3, 6 and 12 months after operation. The preliminary results demonstrate a significant progressive decrease of BMD in the distal femur of the operated knees after TKA, whereas the BMD of the non-operated knees remains stable. The ratio of BMD between the operated femur and the non-operated femur began to decrease 6 months after operation, and was most obvious at the end of the first year (ranging from 7% to 27%). Further investigation is essential to determine the clinical significance of this loss of periprosthetic bone.

Absorptiometry, Photon↗
PubMed1999

Operative management and outcome of complex wounds following total knee arthroplasty.

This study describes the treatment protocol for and the outcome of the management of complex wounds around total knee replacements. An analysis of 28 patients (29 knees) with complex defects who had surgery between January 1, 1986, and July 30, 1996, was performed. A specific management protocol was applied to each knee on the basis of the size and depth of the wound, the presence of infection, and the quality of soft tissue. Primary treatment included local wound care, debridement, and skin grafting or coverage with a fasciocutaneous flap, pedicled muscle flap, or free muscle transfer. Postoperatively, knees were evaluated using the Knee Society objective score. Successful salvage of the lower extremity was obtained in 28 knees (97 percent) and of the knee prosthesis in 24 of 29 knees (83 percent). Secondary plastic surgery procedures were necessary in five knees (17 percent), and secondary orthopedic procedures were necessary in four knees (14 percent). Successful salvage of total knee arthroplasty in the presence of a complex wound requires early identification of infection, aggressive irrigation and debridement, and early appropriate soft-tissue coverage. The use of our proposed algorithm will facilitate management of these complex wounds.

Adult↗
PubMed1993

Micromotion of a noncemented tibial component with screw fixation. An in vivo roentgen stereophotogrammetric study of the Miller-Galante prosthesis.

Micromotion of the tibial component was studied in ten cases of successful arthroplasty for gonarthrosis using the Miller-Galante total knee prosthesis with roentgen stereophotogrammetric analysis (RSA). In six of seven cases, there was a mean of 0.6-mm migration during the first year. Most of this migration occurred as tilt and rotation. Subsidence was seldom found. Inducible displacement was observed in seven cases after one year; in six, deflections were found. In five cases, the inducible displacement was small, approximately 0.3 mm, whereas the sixth case showed inducible displacement of 1.7 mm. The micromotion found in this study was smaller than has previously been reported for other noncemented prostheses. In some of these cases, the RSA data may be compatible with mechanical coupling of the prosthesis to the bone by bony ingrowth.

Aged↗
PubMed2001

Primary arthroplasty of infected hips and knees in special cases using antibiotic-loaded bone-cement for fixation.

As a consequence of successful 1-stage exchange of infected joint prostheses, we decided to treat bacterial infection of the hip or knee by joint resection, synovectomy, and primary implantation of a hip or stabilized knee prosthesis. Since 1984, we have performed this procedure on 51 hips and 32 knees. All operations were preceded by identification of the causative organism and choice of appropriate antibiotics for addition to the bone-cement. The long-term rate of success corresponds to that of 1-stage exchange of infected prostheses. The different anatomic conditions at the hip and knee have to be taken into consideration. This treatment is restricted to special cases and should be performed only in specialized clinics with competent assistance from a bacteriologist.

Aged↗
PubMed2006

[Influence of preoperative range of motion on the early clinical outcome of total knee arthroplasty].

OBJECTIVE: To retrospectively analyze the influence of preoperative range of motion (ROM) and maximal flexion degree on the early clinical outcome of total knee arthroplasty (TKA). METHODS: From January 2000 to December 2003, 97 knees of 65 patients that were underwent total knee arthroplasty with Scorpio posterior-stabilized knee prosthesis were reviewed. There were 55 osteoarthritis patients (81 knees), and 10 rheumatoid arthritis (16 knees). Thirty-three patients were underwent unilateral TKA, 32 patients were underwent bilateral TKA. According to the preoperative ROM of knee, these patients were divided into two groups, one 90 degrees (range, 95 degrees - 140 degrees ). Finally the clinical outcomes of two groups (include ROM, maximal flexion degree, KSS score and function score) were evaluated. Three days later after operation, continuous passive motion (CPM) and active functional exercise of the knee were begun, and the wound healed well in all patients. All these operations were primary total knee arthroplasty. RESULTS: The patients were followed up for average 2 years 5 months (range, 10 months to 3 years 8 months). The average ROM of knee was improved to 101.6 degrees (range, 40 degrees - 140 degrees ) after operation from 84.2 degrees (range, 5 degrees - 140 degrees ) before operation (P = 0.000); the average maximal flexion degree was decreased from 103.5 degrees (range, 25 degrees - 140 degrees ) before operation to 101.6 degrees (range, 40 degrees - 140 degrees ) after operation (P = 0.439); KSS of knee joint was improved to 78.8 points after operation (range, 50 - 95 points) from 19.5 points (-24 - 62 points) before operation (P = 0.000). There was statistically difference between the clinical outcomes (ROM, maximal flexion degree, KSS score and function score) in the two groups before and after operation. Those knees with good preoperative ROM tend to lose flexion, while those with poor preoperative ROM gain flexion after TKA. No revision and deep infection happened. CONCLUSIONS: TKA is a complex operation, the clinical outcome of TKA is mainly determined by the good operation skill, abundant clinical experience and the familiarity with the prosthesis of the surgeon. At the same conditions such as same surgeon, same prosthesis and same physical therapy, preoperative range of motion of knee influence on the early clinical outcome of total knee arthroplasty, knees that have good preoperative ROM have better clinical outcomes postoperatively than those with poor preoperative ROM.

Adult↗
PubMed2006

Heat generated by knee prostheses.

Temperature sensors were placed in 50 knees in 25 patients who had one or both joints replaced. Temperature recordings were made before walking, after walking, and after cycling. The heat generated in healthy, arthritic, and replaced knees was measured. The knee replacements were done using eight different prostheses. A rotating hinge knee prosthesis generated a temperature increase of 7 degrees C in 20 minutes and 9 degrees C in 40 minutes. An unconstrained ceramic femoral prosthesis articulating with a polyethylene tibial prosthesis generated a temperature increase of 4 degrees C compared with a healthy resting knee. The other designs using a cobalt-chrome alloy and high-density polyethylene had temperature increases of 5 degrees-7 degrees C with exercise. Frictional heat generated in a prosthetic knee is not immediately dissipated and may result in wear, creep, and other degenerative processes in the high-density polyethylene. Extended periods of elevated temperature in joints may inhibit cell growth and perhaps contribute to adverse performance via bone resorption or component loosening. Prosthetic knees generate more heat with activity than healthy or arthritic knees. More-constrained knee prostheses generate more heat than less-constrained prostheses. A knee with a ceramic femoral component generates less heat than a knee with the same design using a cobalt-chromium alloy.

Aged↗
PubMed2003

Five year review of the Rotaglide total knee arthroplasty.

In this study we present the outcome for patients with the Rotaglide mobile meniscal knee prosthesis implanted for osteoarthritis. All patients reviewed had this prosthesis implanted as a primary total knee Arthroplasty in Crosshouse Hospital. The minimum follow-up period was 5 years (range 5-8.2). Patients were assessed clinically by the junior author (C.W.) and results were standardised using the Hospital for Specialist Surgery (HSS) knee score. Standard radiographs were taken in antero-posterior and lateral planes to assess for loosening using the Knee Society roentgenographic system. Case notes were then examined for evidence of peri and post-operative problems. Sixty-seven patients (71 knees) were reviewed. Ninety-four percent of patients had an excellent clinical outcome with HSS scores of 85 or more. Two knees were revised, one for meniscal fracture and one for meniscal dislocation. Both of these failures were early in our series and in a total of 312 knees to date there have been no other meniscal failures. No knees were revised for aseptic loosening and there have been no deep infections. We feel this prosthesis offers a safe and effective treatment for osteoarthritis with a good clinical outcome at 5 years with a low level of complications.

Adult↗
PubMed2004

Navigation improves accuracy of rotational alignment in total knee arthroplasty.

Successful total knee arthroplasty is dependent on the correct alignment of implanted prostheses. Major clinical problems can be related to poor femoral component positioning, including sagittal plane and rotational malalignment. A prospective randomized study was designed to test whether an optical navigation system for total knee arthroplasty achieved greater implantation precision than a nonnavigated technique. The primary variable was rotation of the femoral component in the transverse plane, measured from postoperative radiographs and computed tomography images. Sixty-four patients were included in the study. All patients received the Duracon total knee prosthesis. The patients were randomly divided into two groups: Group C patients had conventional total knee arthroplasty without navigation; Group N patients had total knee arthroplasty using a computer-assisted knee navigation system. Analysis showed that patients in Group N had significantly better rotational alignment and flexion angle of the femoral component than patients in Group C. In addition, superior postoperative alignment of the mechanical axis, posterior tibial slope, and rotational alignment was achieved for patients in Group N. The use of a navigation system provides improved alignment accuracy, and can help to avoid femoral malrotation and errors in axial alignment.

Aged↗
PubMed2002

World experience with low contact stress mobile-bearing total knee arthroplasty: a literature review.

This article reviews recent data regarding the low contact stress (LCS) mobile-bearing total knee prosthesis recently published in the literature; conclusions are based on literature controls. The LCS Total Knee System (DePuy Orthopaedics Inc, Warsaw, Ind) has addressed the issues of implant polyethylene wear and implant-generated osteolysis. Patellar implant complications have been minimal despite the use of a mobile, metal-backed component. The original US Food and Drug Administration clinical investigation demonstrated favorable experience with cementless fixation. Results from numerous series indicate that the main problem with a mobile-bearing device is an early prosthetic failure resulting from bearing dislocation or breakage. Inadequate surgical technique will lead to femorotibial malalignment or ligamentous instability, which are factors that commonly result in revision. With the LCS Total Knee System, surgeons can use a tibia-cut-first approach with careful ligamentous balancing and flexion block spacing. The valgus lateral knee approach is an additional technique that has proved useful with this method.

Arthroplasty, Replacement, Knee↗
PubMed1990

Changes in walking ability after knee replacement.

Walking ability has been assessed in 20 patients before and after knee replacement. In 8, who had severe osteoarthritis, a bicompartmental ICLH (Imperial College-London Hospital) prosthesis was used; in 12, with moderate arthritis, the medial side of the joint was replaced by a unicompartmental Brigham prosthesis. Knee function was assessed with the British Orthopaedic Association assessment chart, and walking capacity by the oxygen cost of level walking. Before operation, the function was the same in both groups, but patients with moderate osteoarthritis could walk faster with a lower energy cost than those with severe osteoarthritis. One year after operation, all the patients had improved clinically, alignment had been corrected, and the knees were stable with a satisfactory range of movement. Walking speed was improved; pain and perceived exertion were reduced. The oxygen cost of walking was decreased in patients with a unicompartmental arthroplasty, but not in patients with a total replacement. An uneconomic walking pattern, acquired before operation in those with severe osteoarthritis, was considered to be the reason why walking efficiency was not improved. The walking ability in patients with moderate osteoarthritis recovered to almost normal after unicompartmental replacement.

Aged↗
PubMedDate not supplied

[KMFTR (Kotz Modular Femur Tibia Reconstruction System) modular tumor endoprosthesis system for the lower extremity].

206 patients with tumorendoprosteses of the KMFTR-type at the lower extremity were operated at the Institute Rizolli Bologna and at the University Clinic of Vienna. The minimum follow up was 2 years (mean 3.2, max. 8 years). In order to bridge the defect caused by tumor resection the proximal femur was replaced in 42 cases, the distal femur in 119 cases and in 6 patients a total femur prosthesis was used. The proximal tibia was replaced in 35 cases and in 4 cases a total knee prosthesis was implanted. Clinical evaluation according to Enneking revealed 71.6% excellent and good results. In 83.4% the radiological score was higher then 20. We saw deep infections in 8.2% (17 patients), breakage of the prosthesis in 6.8% and aseptic loosening in 5.8%. 3 patients had to be amputated due to infection. In the remaining cases of infection in 66% of the patients healing was observed. All cases of aseptic loosening or breakage could be revised successfully by an exchange of the prostheses and therefore salvage of the leg was achieved.

Adolescent↗
PubMed1991

[Biomechanics of the normal and prosthetic knee].

The knee joint is characterized by particular kinetics due to asymmetry of the femoral condyles and to angulation of the extensor system. During flexion, this results in a rolling/sliding movement in which the upper surface of the tibia recoils under the femoral condyles, combined with an automatic movement of medial rotation from extension towards flexion of the tibia beneath the femur. The articular contact areas are very small, ranging from 10 to 20 cm2 for the femorotibial articulation and barely reaching 4 cm2 for the femoropatellar articulation. These areas are subjected to extremely strong pressures amounting to 7 times the body weight in the femorotibial articulation during walking, and up to 1500 N (20 times the body weight) during simple flexion. However, the most fundamental element of biomechanics is the instability of the knee joint which is dependent on its menisco-ligamentous system. In addition, the menisci increase the femorotibial contact area, thereby relieving some of the pressure. The knee prosthesis concept is based on the stability of the prosthetic knee. In patients with healthy ligaments, non-strained prosthesis can be used, in which case part of the forces proceeds directly from one bone to the other via the ligaments, and there are only minimal stresses between the two prosthetic pieces and at the prosthesis/bone interface. But when the ligamentous system is defective or incomplete, or when the axial alignment is so upset that ligaments must be severed, one must use prostheses that are partly or totally constrained.(ABSTRACT TRUNCATED AT 250 WORDS)

Biomechanical Phenomena↗