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PubMed1978

Experience with the Melbourne knee prosthesis, based on the first 35 operations over a three-year period.

The Melbourne knee prosthesis is an improved hinge prosthesis. Its component parts are constructed of a chrome cobalt alloy and ultrahigh molecular weight polyethylene. The hinge has a range of flexion of 120 degrees, and while flexed, can rotate 15 degrees in either direction. Over the past three years a total of 45 prostheses have been inserted in patients with chronic degenerative arthritis of the knee joints. This survey covers the first 35 operations. The most gratifying result has been a dramatic relief of pain in 87.5% of patients. There have been few complications, and no prosthesis has had to be removed. There have been no mechanical failures of the prosthesis itself.

Adult↗
PubMed1989

The Minns meniscal knee prosthesis: biomechanical aspects of the surgical procedure and a review of the first 165 cases.

The Minns knee prosthesis has been designed so that the ligaments, soft tissues and musculature about the knee can return to their full functioning during the movement and loading that occur in usage. By utilising a third component made of polyethylene that slides back and forth in a straight line between the metallic femoral and tibial components, the knee is able to roll and slide at the plastic/metal junctions without creating high forces and loosening moments on the tibial component. The tibial tray has a central cut-out to allow the functioning of both cruciate ligaments, and the femoral component is of the total condylar design. Experimental and theoretical studies on the functioning and clinical performance of this design and the biomechanical implications of the technique of surgical implantation are described. The results of the first 165 cases, followed up for a maximum of 5 years, were ranked according to pain, mobility, and restoration of function; 75% were rated as excellent, both subjectively and objectively, 13% as good, and 9% as fair. The average range of motion measured at least 6 months postoperatively was 103 degrees. Eight knees dislocated laterally because of instability and were successfully revised using the sliding plateau without being necessary to remove the metallic components. Minimal wear has been seen on the removed menisci up to 4.5 years' use.

Biomechanical Phenomena↗
PubMed2000

The Oxford unicompartmental knee prosthesis: a 5-year follow-up.

We present our medium-term results with the Oxford unicompartmental knee prosthesis for unicompartmental osteoarthrosis. After an average of 58 months the mean on the Hospital for Special Surgery knee score in 38 medial and 3 lateral prostheses (39 patients) was 87. There were three revisions; in the remaining 36 patients the results were: 29 excellent, 3 good, 2 moderate, and 2 poor. In two of the three revisions and in two of the four poor and moderate results, the indications for the procedure were debatable. Our findings confirm the good results reported in other studies and underline the importance of adhering to strict indications to reduce the number of poor results.

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PubMed1997

[Complete knee prosthesis in severe genu valgum. Retrospective review of 90 knees surgically treated through the anterio-external approach].

The authors have made a retrospective study of 90 total knee arthroplasties performed through a lateral approach in knees with a valgus deformity superior or equal to 10 degrees. The mean function score increased from 35.9 to 73.2 postoperatively; the mean knee score increased from 60.2 to 93.6. Radiological evaluation of the mechanical angle (HKA) showed 16 degrees of valgus deviation preoperatively versus only 1.5 degrees of valgus post-operatively. A strict operative technique using a lateral approach in severe valgus knee deformity makes it possible to reproducibly achieve joint stability with good mobility and a neutral mechanical axis in total knee arthroplasty.

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PubMed1990

Dislocation of a posterior stabilized total knee prosthesis. A report of two cases.

Posterior stabilized knee prostheses have been recommended for knees with posterior cruciate deficiency, as well as for knees with prior patellectomy. Two cases are presented in which a complete dislocation of a Kinematic II Stabilizer prosthesis occurred after primary knee arthroplasty. The mechanism of dislocation was a varus or valgus stress while the knee was flexed. This previously unreported complication of dislocation after primary knee arthroplasty with a posterior stabilized knee prosthesis was, we believe, due, in part, to the design of this prosthesis, which provides little mediolateral stability in flexion, in combination with a mild degree of laxity of the collateral ligaments. This complication could be prevented by use of a prosthesis with greater inherent mediolateral stability.

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PubMed1991

[Angiosarcoma after total knee prosthesis. Apropos of a case].

The authors describe the case of an angiosarcoma associated with a knee prosthesis. The appearance of a malignant tumour in the area of the implantation of a metallic prosthesis is rare. The pathogenesis of this association is still unknown. The authors make an analysis of the problem on the basis of a review of the literature.

Aged↗
PubMed1981

The Attenborough total knee prosthesis. Results of 25 operations evaluated according to two different assessment systems.

The Attenborough stabilized gliding total knee prosthesis was used in cases of severely damaged, highly unstable or deformed knees. Twenty-five operated cases were followed for 1 1/2 years (range 12-28 months). The results were assessed according to two different knee evaluation systems: The Lotke & Ecker knee evaluation index and the knee function assessment chart (BOA chart) suggested by the British Orthopaedic Association. The overall results were excellent or good in 84 per cent (21/25) of the cases according to both systems, but when considering the improvement in individual clinical features the BOA chart results were more optimistic. Neither of the systems takes into consideration that the results are influenced by possible disorders in other joints. If only the function of the knees was being judged the results of the operations with the Attenborough prosthesis were excellent or good in 96 per cent (24/25) in this series. In general the results to be as good as those obtained in less disabled knees treated with compartmental prostheses. As more extensive surgery and bone resection is needed for insertion of the Attenborough prosthesis compared with compartmental prostheses, its use should be restricted to severely damaged knees which would otherwise be treated with a hinged prosthesis or an arthrodesis.

Adult↗
PubMed2003

A mobile-bearing total knee prosthesis compared with a fixed-bearing prosthesis. A multicentre single-blind randomised controlled trial.

Before proceeding to longer-term studies, we have studied the early clinical results of a new mobile-bearing total knee prosthesis in comparison with an established fixed-bearing device. Patients requiring bilateral knee replacement consented to have their operations under one anaesthetic using one of each prosthesis. They also agreed to accept the random choice of knee (right or left) and to remain ignorant as to which side had which implant. Outcomes were measured using the American Knee Society Score (AKSS), the Oxford Knee Score (OKS), and determination of the range of movement and pain scores before and at one year after operation. Preoperatively, there was no systematic difference between the right and left knees. One patient died in the perioperative period and one mobile-bearing prosthesis required early revision for dislocation of the meniscal component. At one year the mean AKSS, OKS and pain scores for the new device were slightly better (p < 0.025) than those for the fixed-bearing device. There was no difference in the range of movement. We believe that this is the first controlled, blinded trial to compare early function of a new knee prosthesis with that of a standard implant. It demonstrates a small but significant clinical advantage for the mobile-bearing design.

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PubMed1980

Preliminary results of the Sheehan total knee prosthesis.

A review of 50 knees in 42 patients operated upon between August, 1973 and November, 1976 is presented. Following initial good results, problems have been encountered with the passage of time. Complications due to design faults, selection, and technical pitfalls are analysed. Patients who have grossly unstable and deformed knees are not suitable for this type of prosthesis. The high density polyethylene central flange in the tibial component is not strong enough to withstand valgus or varus forces. Full correction of valgus, varus, or flexion deformities is essential if late complications are to be avoided. Associated external rotation deformities in grossly valgus knees have to be fully corrected to prevent late dislocation of the patella. Our conclusion is that at present there is a place for both the hinged and hingeless type of prosthesis in total knee replacement.

Adult↗
PubMed1988

Use of a total condylar knee prosthesis for treatment of osteoarthritis and rheumatoid arthritis. Long-term results.

Between May 1975 and December 1979, 113 patients had 153 arthroplasties using a total condylar knee prosthesis. Thirty patients (forty-two knees) died, and one (two knees) was lost to follow-up. Thirty-eight of these forty-four knees had been followed for more than two years, and none had had a revision. The remaining eighty-two patients (109 knees) were followed for an average of nine years (range, seven to 11.5 years). At the time of the latest examination, ten had had a revision for various reasons. For the ninety-nine knees that had the original prosthesis, the findings were compared with those of an evaluation that had been done four years postoperatively. The average over-all knee score was found to have decreased between the four-year and the latest follow-up evaluation, primarily because of a 7-point decrease in the score for function. The rate of infection was 0.6 per cent. The knees that had had patellar resurfacing had better over-all scores and better scores for pain than those that had not. This was particularly true in the patients who had osteoarthritis. The results of arthroplasty using a total condylar prosthesis appeared to be consistent and durable. Although there was a decrease in the quality of the functional result with increasing age, the patients reported consistent relief of pain.

Adult↗
PubMed1981

The variable-axis knee prosthesis. Two-year follow-up study.

This study reports the clinical results following knee replacement with the variable-axis knee prosthesis. All patients have been followed for a minimum of two years. The first consecutive fifty-two patients, comprising a total of fifty-five knee replacements, were personally reviewed by an independent evaluator. The results on a subjective basis consisted of 79 per cent good to excellent results, 15 per cent fair results, and 6 per cent failures. Failures were related to infection or continued pain. Fair results reflected some patellar discomfort or instability. There was no detectable clinical loosening of the components in any patient. To date, the design of the variable-axis prosthesis appears to offer promise in the control of the complication of prosthetic loosening.

Adult↗
PubMedDate not supplied

[Minimally Invasive Stryker-Osteonics unicondylar knee prosthesis with metal-backed tibia component: a 5-year follow-up].

INTRODUCTION: The aim of this study was to evaluate the medium-term results of minimally invasive unicompartmental knee joint arthroplasty with a metal-backed tibia component. MATERIAL AND METHODS: Ninety-one unicompartmental knee replacements with a metal-backed tibia component, type SCR-Stryker Osteonics, were implanted in a minimally invasive technique in 91 patients between 1997 and 1999. The evaluation of medium-term results was based on The Knee Society Clinical Rating System by Insall and Scott and was done at 6 weeks, 1, 3 and 5 years after surgery. This rating system is based on the clinical and symptoms of the patient (maximum score 100). RESULTS: Preoperatively, the average knee score was 57.6 (44-66), the function score 63.3 (48-71). Throughout the period of investigation all patients had an increased knee and function score. One year after surgery the knee and function scores increased to 94.8 (39-100) and 93.6 (75-100). Five years post-implantation only 64 patients could be re-evaluated but they also had a knee and function score corresponding to the 3-year results [knee score: 98.2 (94-100); function score: 98.9 (85-100)]. Revision surgery using a total knee prosthesis was performed in 3 cases. DISCUSSION: The unicompartmental knee arthroplasty was a good surgical method for managing medial, unicompartmental arthritis of the knee joint. The results presented by the authors and corroborated by many literature data provide evidence that unicompartmental arthroplasty is of great importance in the treatment of unicompartmental knee arthritis. The results achieved by the minimally invasive technique of a unicompartmental knee arthroplasty with a metal-backed tibia component of the type Stryker-Osteonics were equal to the conventional surgical technique in literature. Good indications were patients older than 60 years with normal weight and normal sports activity. Well-functioning collateral and cruciate ligaments were mandatory. Moreover, the minimally invasive technique may lead to a shorter time of rehabilitation because of the reduced soft tissue damage.

Adult↗
PubMed1991

The total condylar III knee prosthesis in elderly patients.

Sixteen knee arthroplasties using a total condylar III prosthesis were performed in 14 patients with an average follow-up period of 4.5 years and a minimum follow-up period of 3 years. Eleven of the sixteen knee arthroplasties were revision prostheses. The average age was 71 year, with all but three patients being 69 years of age or older. In this age group, fifteen of sixteen implants had a good to excellent Hospital for Special Surgery (HSS) knee score at the most recent follow-up evaluation. One patient had a fair score, the result of a remote postoperative proximal tibial fracture, and requires a long leg brace for ambulation.

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PubMed2005

Polyethylene wear particle generation in vivo in an alumina medial pivot total knee prosthesis.

Polyethylene wear particle generation is one of the most important factors affecting mid- to long-term results of total knee arthroplasties. It has been reported that the medial pivot total knee prosthesis (MP) design and alumina ceramic femoral component reduce polyethylene wear. The aim of this study is to evaluate in vivo polyethylene wear particle generation in the newly introduced alumina MP, in comparison with a metal MP. Synovial fluid was obtained from 11 knees with alumina MP and 15 knees with metal MP at nine months after the operation. Polyethylene particles were isolated, and examined using scanning electron microscope and image analyzer. Total number of particles in each knee was 7.10+/-2.86x10(6) in alumina (mean+/-standard error), and 5.70+/-2.82x10(7) in metal MP (p=0.048). Particle size (equivalent circle diameter) was 0.78+/-0.04 microm in alumina, and 0.66+/-0.06 microm in metal MP (p=0.120). Particle shape (aspect ratio) was 1.52+/-0.05 in alumina, and 1.88+/-0.11 in metal MP (p=0.014). Apart from the femoral component, the material and manufacturing method of polyethylene insert differed between the two groups, although the sterilization method was the same. Alumina MP generated fewer and rounder polyethylene wear particles than metal MP in early clinical stage, and could potentially reduce prevalence of osteolysis and aseptic loosening.

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PubMed1988

Patellofemoral functional results and complications with the posterior stabilized total condylar knee prosthesis.

The authors reviewed 73 knee arthoplasties performed with the Posterior Stabilized Total Condylar prosthesis, with an average follow-up period of 5.5 years. The function of the patellofemoral articulation was specifically analyzed. Patients with documented or suspected tibiofemoral problems were excluded. Using the Hospital for Special Surgery knee rating system, 48 knees (66%) had excellent, 20 had good (27%), and 5 (7%) had fair results. Patients with unilateral disease were able to negotiate stairs and transfer normally in 64% and 100% of the cases, respectively. The most frequent patellofemoral problem was impingement (21%), but reoperation was needed in only one patient. Stress fracture of the patella and subluxation were rare. A medial tilt of the patella on the axial view had no apparent ill effect. The patella was lowered 12 mm on average as a consequence of the standard bone resection sequence and insertion of the tibial component. The patella was significantly lower in patients with impingement than in normal joints. Routine complete patellofemoral resurfacing is advised in total knee joint arthroplasty. Complications are infrequent with appropriate prosthetic design and due technical care.

Adult↗