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PubMedDate not supplied

[Does the NexGen LPS flex mobile knee prosthesis offer advantages compared to the NexGen LPS?--a comparison of clinical and radiological results].

UNLABELLED: Under experimental conditions, mobile bearing knee prostheses have several advantages. The optimized congruence of the tibio-femoral joint surface allows a knee flexion of more than 120 degrees without creating instability or increase of wear. AIM: The aim of this study is to compare the results of a prospective randomized study after implantation of the mobile bearing knee prosthesis NexGen LPS Flex with the results of the fixed bearing knee prosthesis NexGen LPS. METHODS: Sixty patients underwent a total knee replacement (30 patients with NexGen LPS Flex mobile, 30 patients with NexGen LPS) via a mid vastus approach. All implants were cemented (Palacos) including the patella resurfacing. We evaluated the Hospital for Special Surgery Score (HSS) and different radiological parameters (maximal flexion, positioning of the implants, leg axis) preoperatively as well as 3 months and 3 years (34.6 +/- 7.3 months) postoperatively. RESULTS: After 3 months the NexGen LPS Flex group showed better results in the scores for pain, range of motion (122.5 degrees vs. 107.33 degrees ) as well as the overall HSS (87.21 vs. 82.68 points) compared to the NexGen LPS group. Three years postoperatively there were no differences in all scores between the two groups. CONCLUSION: The theoretical advantages of the mobile bearing knee prostheses were reflected in the clinical results only partly and temporarily. Probably the results of long-term follow-ups will show characteristic advantages or disadvantages of mobile bearing knee prostheses.

Aged↗
PubMed1993

[Low contact stress knee prosthesis system. Results and complications].

This paper reports on the global results of the low contact stress knee prosthesis system with mobile weight bearing surfaces. The follow-up result of 918 cemented and 963 cementless knee prostheses was in more than 90 per cent excellent and good 2-8 years after the operation. The ratio of complications connected with the construction decreased to 2.8 per cent in cementless prostheses. In the cemented series less variations of size were available and the problems with the tibial component were under 2, the complications with the patella remained under 1 per cent. The more than 12 years clinical use of the mobile weight bearing knee prosthesis system proved the success of the solution concerning the basic construction.

Aged↗
PubMed2000

Revision of failed metal-backed patellar component of Miller/Galante-I total knee prosthesis.

Of 38 Miller/Galante-I total knee prostheses implanted between 1987 and 1990, 20 (53%) were revised. Failed metal-backed patella (15 knees; 40%) was the most frequent reason for revision. In most patients, the components were found well fixed to bone. The purpose of this study was to describe the revision technique we used for failed metal-backed patella. Total revision of all components would be ideal. However, removal of all components results in large bone loss, large blood loss, and a longer operation time. Because of the patients' relatively old age (78.7 years), less demanding activities of daily life (ADL), and the lower body weight of the Japanese patient, we chose a less invasive approach. The revision technique had the following features: (1) the grooved femoral component was not replaced, (2) the failed patellar component was replaced by an all-polyethylene patella, (3) synovectomy was performed, and (4) realignment of patellar tracking was done by lateral release and medial imbrication of the quadriceps mechanism. The mean follow-up after revision was 2 years, 4 months, and good short-term results were obtained. This less invasive approach would be beneficial for elderly patients whose ADL are less demanding.

Aged↗
PubMed1992

Mathematical modelling and field trials of an inexpensive endoskeletal above-knee prosthesis.

The swing-phase motion of the shank of an above-knee prosthesis has been modelled mathematically. An inexpensive endoskeletal prosthesis was designed using the Jaipur foot and conduit pipes with a hinge joint for the knee. Results of field trials and the modelling indicate that a very simple above-knee prosthesis can give near normal gait at "normal" walking speeds on flat surfaces. The swing of the shank is most sensitive to the timing of toe-off.

Acceleration↗
PubMed1979

[Experimental and clinical studies on the Jikei total knee prosthesis (author's transl)].

Total knee prostheses for a dog were developed and were inserted into knee joints of seven adult dogs to study the mobility of the artificial joint, the degree of fixation to bone and the durability of the prosthesis, to examine the reactions in the surrounding tissues and the internal organs in the JIKEI total knee prosthesis in clinical use. As a result of surgery, it was proved that the length in the hinged part of the prosthesis needed to be seventy percent of the length of the excised area of the joint to gain good mobility and supportability of the knee joint after surgery. As a result of findings based on necropsy, wear at the hinged part of the prosthesis was mild and debris caused in wear was not harmful for the living body if breakage does not occur there. Histopathological findings revealed that collagenous fibrous tissue with new bone formation was observed on the inner wall of the bone around the stem of the prosthesis four months after surgery. Then it was proved that the fixation of the prosthesis to the bone was sufficient. Therefore the author would like to mention that bone cement is not necessary for the fixation between bone and prostheses. The JIKEI total knee prosthesis (universal type) based on the results of these experimental studies has been developed and was used to the clinical cases. The clinical results until four years after surgery have been most satisfactory with loss of pain, good supportability and movement of joints in almost all of the cases.

Adolescent↗
PubMed1982

An improved above-knee prosthesis with functional versatility.

An above-knee prosthesis is described which is designed to permit the patient to assume easily the squatting and sitting cross legged postures which are a part of routine living in Afro-Asian countries. The prosthesis incorporates a multibar linkage mechanism which co-ordinates knee flexion and extension with ankle dorsiflexion and plantarflexion, and a thigh rotation system fitted at the level of the knee axis.

Amputation, Surgical↗
PubMed1982

Bone scanning for the evaluation of knee prosthesis.

Twenty-six knees were scanned after total replacement to evaluate the relationship between bone scan, pain, the presence of a radiolucent line at the bone-cement interface and loosening. A radiolucent line was often accompanied by an increased uptake over the affected condyle, but there was no significant relationship with pain or loosening.

Bone Cements↗
PubMed1981

[GUEPAR hinge knee prosthesis (author's transl)].

Early and late results of Guepar hinge knee prosthesis have been evaluated on a serie of 184 operations performed before January 1st 1974. There were 3 immediate deaths and 26 before 5 years. 19 prosthesis were removed. 126 knees had degenerative osteoarthritis, 52 rheumatoid arthritis. 22 had been operated on before. Patellar displacement, present in 27 p. 100 of the cases was the most frequent cause of complaint: pain or instability, proportional to the severity of displacement made reoperation necessary in 10 p. 100 of the patients. Addition of a patellar prosthesis was the most successful treatment as far as pain is concerned: it is probably advisable as a primary procedure. Deep infections occurred in 8,3 p. 100 of the cases, unfrequently after 2 years. Healing was obtained in all cases either by revision or by removal and arthrodesis: but functional results were poor except when fusion was achieved, in half of the cases of arthrodesis. Loosening occurred in 16 p 100 of the cases mainly as the consequence of insufficient technique. It was frequently tolerated: reoperation was necessary in 6 p. 100 of the total. Late functional results were evaluated in 99 cases with a follow-up of 5 to 8 years. Apart from loosening, the results did not deteriorate. 60 p. 100 are evaluated as excellent or good, 29 p. 100 fair, and 11 p. 100 bad. With due consideration of these results election of this prosthesis should be limited to special cases. To prevent complications, the use of a patellar prosthesis, of reinforced models, and of cementing under pressure is advisable.

Adult↗
PubMed1994

Treatment of femoral fracture above a knee prosthesis. 18 cases followed 0.5-14 years.

We reviewed 16 patients who sustained 18 fractures above a total knee prosthesis. 5 fractures were undisplaced and were treated with either skeletal traction or a plaster cylinder. 3 did well, 1 patient suffered a cerebral vascular accident while still in plaster and 1 patient died of heart failure while on skeletal traction. 7 displaced fractures were treated initially with skeletal traction. 1 patient had a nonunion of the fracture and 2 a malunion and malfunction of the knee. 4 underwent various operations later because of malalignment and nonunion of the fracture with poor functional results. 6 displaced fractures were treated with immediate internal fixation. 5 recovered well and returned to pre-fracture activities. 1 patient's plate broke and further surgery was needed. We conclude that displaced fractures above a knee prosthesis should be treated with immediate stable internal fixation and early mobilization. Nonoperative treatment was satisfactory only for minor undisplaced fractures.

Aged↗
PubMed1992

Scintimetric study of the bone response around noncemented knee prosthesis. Preliminary results.

The bone response to a noncemented knee prosthesis was observed by quantified isotopic gammagraphy. One hundred six sequential scintimetric explorations were performed in 36 patients with total knee arthroplasty. Fifteen areas of interest were taken into consideration and their gammagraphic analyses were compared with radiologic findings during a postsurgery period of 24 months. Starting with a very high radionuclide uptake level obtained in the first postsurgery level, a gradual decrease was correlated with osteoblastic activity. In this first evaluation, the gammagraphic response around the implant is different in biologic prostheses than in cemented ones. These data may be useful for evaluating implants in orthopedic surgery.

Female↗