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At least 217 records · Page 12Linked to original sources
PubMed1982

[Articular chondrocalcinosis and sliding knee prosthesis].

The authors examined 24 files, involving 24 cases of arthroplastic knee surgery and revealing an articular chondrocalcinosis which was histologically proven. The mean post-operative follow-up took place in 30 months (1 to 5 years). The results were neither spectacular nor catastrophic. The overwhelming majority of the patients were satisfactory. 60% of those who had undergone surgery showed good objective results. Radiological aggravations were rare; the latter were not necessarily parallel to the clinical results. In conclusion, chondrocalcinosis does not appear to be an aggravating factor in the prognosis for sliding unicompartmental arthroplastia. The results were completely comparable to those in cases of osteoarthrositis without calcinosis. In both cases, the same encouraging results were observed, as well as the same doubts and uncertainty as to the future.

Calcinosis↗
PubMed1995

[2-stage exchange in the treatment of infected knee prosthesis].

We report our experience with the treatment of infected total knee arthroplasties with a two-stage procedure during the period between 1992 and 1995. The two-stage procedure as a cure for infected total knee arthroplasty is a reliable and reproducible method of treatment. The infection healed in 86% of cases, and all patients with a follow-up of more than 1 year were satisfied with the result achieved. Also the objective values proved that the outcome of this severe complication of total knee arthroplasty was favorable. The two-stage exchange procedure is recommended as the treatment of choice for infected total knee arthroplasty wherever possible.

Aged↗
PubMed1997

[Dislocation of the femoral component of an unicondylar knee prosthesis. Apropos of a case].

INTRODUCTION: Femoral component dislocation in unicondylar knee arthroplasty is rare. One case is reported. MATERIAL AND METHODS: A 59 years old man required revision of his unicondylar knee arthroplasty for loosening and dislocation of the femoral component 3 years after its insertion. Revision was performed and we found a technical error: distal and posterior femoral cut was too thin, and with components in place, there was a tendancy for the components to "rock" as the knee was flexed. The implants were too tight in flexion. A new unicondylar knee arthroplasty was performed. DISCUSSION: The posterior condylar bone resection should reach at least the thickness of the metal implant. It is better to resect slightly too much of the posterior condyle than too little in order to avoid tightening of the knee in flexion. The femoral component must accurately reproduces the anterior-posterior dimension of the femoral condyle. CONCLUSION: With better selection of patients and surgeons who are more familiar to this type of procedure loosening and dislocation of an unicondylar knee arthroplasty should be avoided.

Arthroplasty, Replacement, Knee↗
PubMed1982

Biologic fixation and bone modeling with an unconstrained canine total knee prosthesis.

To study the effects of dynamic loading on biologic fixation, an unconstrained type of prosthesis was designed for total replacement of the knee joint of dogs. The femoral component was fabricated from cast cobalt-based surgical alloy. The tibial component was fabricated from surgical grade, ultra-high molecular weight, high density polyethylene. Both components were designed for initial stabilization at surgery by mechanical interlock with bone. In addition, the bone-interfacing surface of the metal component was made porous and the stem of the polymer component was grooved to permit the subsequent ingrowth of tissue. Knee arthroplasty was performed on a total of six beagles. The prostheses were monitored for periods of 20 months and demonstrated an overall excellent stability and functionality. Each tibial component became stabilized by the formation of a thin, surrounding shell of osseous tissue. Interposed between this bone and the implant was usually a thin layer of fibrous tissue, suggesting micromovement during loading. Each femoral component became solidly fixed by bone growth into the porous surface. The altered stress state in the region of the implant eventually resulted in reactive bone modeling, with both bone formation and resorption occurring along the length of the implant.

Animals↗
PubMed1989

Results and complications after arthroplasty with a totally constrained total knee prosthesis (GUEPAR).

A series of 51 patients (55 knees) with implanted GUEPAR totally constrained endoprosthesis was followed up clinically and radiologically for a mean of 5.0 years (range 1.5-11.8 years). Good relief of pain, increased range of knee movement and of walking capability were observed. There was, however, an unacceptable amount of severe complications. Three endoprostheses had to be removed and arthrodesis performed. Revision arthroplasty was carried out in 8 cases due to aseptic loosening of the prosthesis. In 25 cases lateral displacement or total dislocation of the patella was confirmed with tangential patellar X-ray projections. We suggest that the GUEPAR totally constrained total knee endoprosthesis and similar constructions should be chosen in only special cases, when aged patients have extremely damaged and unstable knee joints and non-constrained prostheses are not considered suitable.

Adult↗
PubMed2002

Anthropometry of the proximal tibia to design a total knee prosthesis for the Japanese population.

Anthropometric data on proximal tibiae of 100 knees in 80 Japanese patients undergoing total knee arthroplasty were obtained. Anterior-posterior (AP) and medial-lateral (ML) lengths of the tibia were measured on computed tomography scans and intraoperatively on tibial resection surfaces. A special small component is unnecessary, and size variation should focus on ML length of 65 to 75 mm because this includes 90% of women's knees. AP-to-ML ratio had a negative correlation with ML length, indicating that small knees were longer in the AP direction. Most prostheses had AP mismatch up to 5 mm for small women's knees. These data could provide the basis for designing the optimal tibial component for most of the Asian-Pacific population.

Aged↗
PubMed2002

Rotationplasty after failure of a knee prosthesis for a malignant tumour of the distal femur.

Failure of massive knee endoprostheses implanted for malignant tumours of the distal femur in children presents a difficult problem. We present the results of rotationplasty undertaken under these circumstances in four boys. They had been treated initially at a mean age of 9.5 years for a stage-IIB malignant tumour of the distal femur by resection and implantation of a massive knee endoprosthesis. After a mean period of eight years and a mean of four operative procedures, there was failure of the endoprosthesis because of aseptic loosening in two and infection in two. Function was poor with a mean Musculoskeletal Tumor Society score of 7.5/30, and considerable associated psychological problems. At a mean follow-up of 4.5 years after rotationplasty there was excellent function with a mean score of 27.5/30 and resolution of the psychological problems.

Adolescent↗
PubMed1977

Conformity in condylar replacement knee prosthesis.

Experiments were carried out to determine the optimum conformity between the femoral and tibial condyles in condylar replacement knee prostheses. Wear tests and observations from removed prostheses indicated that both high and low conformity produced characteristic abrasion and fatigue. Partly conforming condyles provided stability under load-bearing but allowed laxity to occur. Fixation to resist the various forces on the tibial components was enhanced by a short central intramedullary peg. Partial conformity is proposed as the optimum configuration between femoral and tibial components.

Biomechanical Phenomena↗
PubMed2001

Extensive osteolytic cystlike area associated with polyethylene wear debris adjacent to an aseptic, stable, uncemented unicompartmental knee prosthesis: case report.

We present the case of a patient who after uncemented unicompartmental knee arthroplasty developed a large osteolytic cystlike area in the lateral aspect of the tibial metaphysis, contralateral to a well-fixed tibial component at revision surgery. The lesion contained fibrotic soft tissue, evidence of a foreign-body giant cell reaction and polyethylene particles, but no metal wear debris, infection, or malignancy. This case demonstrates that there is a direct communication between the joint cavity and the cyst.

Bone Cements↗
PubMed2006

[Influence of rotatory malposition of femoral implant in failure of unicompartimental medial knee prosthesis].

PURPOSE OF THE STUDY: Rotatory malposition of the femoral component of a unicompartmental knee arthroplasty (UKA) is a key element of mechanical failure despite proper alignment and position of the tibial implant. The purpose of this study was to describe a method for measuring femoral implant rotation on the anteroposterior x-ray using an original geometric model. MATERIAL AND METHODS: 276 medial UKA (227 non-cemented Uni Goeland, Depuy; Uni, AMP) and 49 cemented (Miller-Galante, Zimmer) were reviewed and analyzed at a mean 11 years (range 7 - 15) using the Knee Society Score. Mean objective and functional scores were 43 and 47 points preoperatively. Postoperative alignment and position of the femorotibial contact point were determined. The frontal and sagittal position of the tibial plateau was noted by the angle formed with the mechanical axis. Angles alpha and B of the femoral implant formed between the mechanical axis and the greater condylar axis and the inferior condylar line passing through the apex of the condylar convexity respectively were measured on the AP view. Frontal rotation (angle B) of the femoral implant reflected the orientation of the distal condylar cut. The frontal measurement (angle alpha) was validated using simple geometric formulas: knowing angles alpha and B and the size of the implant and the displacement of the point of contact was measured together with the true rotation of the femoral implant or anteroposterior divergence, function of the difference alpha-B which is its frontal projection and reflects the orientation of the posterior condylar cut. RESULTS: Mean alignment was 3 degrees varus. At last follow-up, outcome was satisfactory in 81.2% of the knees (224 UKA). Mean objective and functional scores were 90 and 87 points. Angles alpha and B were parallel and orthogonal to the mechanical axis or off by less than 4 degrees external rotation (+6 degrees to -4 degrees). The mean difference alpha-B (frontal projection of the femoral implant transverse rotation) was 1 degrees. The point of contact was 4 mm or less from the middle of the tibia. Failures were observed in 18.8% of knees (52 UKA): 4 for diverse reasons and 48 for mechanical failure, including 3 with polyethylene wear without loosening (two by eccentric point of contact and neutral position and one by inverted misalignments). 45 UKA (16.3%) presented loosening of the tibial plateau alone with rotatory femoral malposition: mean a angle off 13% from the mechanical axis (+16 degrees to -9 degrees ), mean B angle off 8 degrees (+12 degrees to -8 degrees), mean alpha-B difference 5 degrees , femoral implant in square position on polyethylene with a peripheral point of contact > or 5 mm from the middle of the tibial plateau. The tibial implant exhibited mean varus of 1.5 degrees. DISCUSSION: The main cause of failure was rotatory malposition of the condylar implant often associating frontal with transversal rotation. This increased mediolateral translation of the point of contact during knee motion causing abrasion and excessive pressure on the medial portion of the plateau. Frontal malrotation externalizes the posterior cut on the condyle tilted by the varus position, without correcting the varus of the mechanical axis in flexion. To avoid such prosthetic malrotations, three corrections must be made before making the bone cuts: cancel the external rotation of the condyles in flexion by positioning the distal cut guide in extension; re-establish the mechanical axis by reducing the internal tilt of the condyles resulting from the varus position both in extension (distal cut) and flexion (posterior cut). Improved instrumentations and reproducible techniques are needed to re-establish the 3D anatomic orientation of the femoral component, a key element for longer life of unicompartmental prostheses. This method for measuring the rotation of the femoral implant and the displacement of the point of contact using a geometric model applied to the AP view is useful for better understanding UKA failures.

Adult↗
PubMedDate not supplied

[2-to-4-year results of the cementless application of the PCA unicondylar knee prosthesis. Clinico-radiological histomorphological study].

Since 1984 35 PCA unicondylar endoprostheses of the knee joint were implanted due to unicondylar high grade osteoarthritis or Morbus Ahlbäck. 19 endoprostheses with a minimum follow up of two years were investigated. Three implants had to be changed because of an aseptic loosening and were retrieved for histomorphological analysis. The implants which were found clinically stable were graded from the patients point of view as excellent to fair. Only in 5 cases, however, no seam at the implants interface was found in the radiological screening. These radiological lucencies can only be seen in x-ray amplifier controlled x-rays. No correlation has been seen of the clinical performance to the type of anchorage. The position of the implants which had revision was fair in one case and poor in two cases, although a correlation between the radiological seam and the position of the implant was not found. The histological analysis showed up a well developed osseointegration on the femoral component in the area of the porous coated pegs. At the interface to the bone of the tibial components intervening connective tissue has been found. 3 implants still in function have to be seen as endangered to loosening and further 8 prostheses with partial radiolucencies might become potential failures.

Aged↗