The aim of this study was to investigate whether wear and backside deformation of polyethylene (PE) tibial inserts may influence the cement cover of tibial trays of explanted total knee arthroplasties (TKAs). At our retrieval centre, we measured changes in the wear and deformation of PE inserts using coordinate measuring machines and light microscopy. The amount of cement cover on the backside of tibial trays was quantified as a percentage of the total surface. The study involved data from the explanted fixed-bearing components of four widely used contemporary designs of TKA (Attune, NexGen, Press Fit Condylar (PFC), and Triathlon), revised for any indication, and we compared them with components that used previous generations of PE. Regression modelling was used to identify variables related to the amount of cement cover on the retrieved trays.Aims
Methods
Vitamin E-infused highly cross-linked polyethylene (E1) has recently been introduced in total knee arthroplasty (TKA). An in vitro wear simulator study showed that E1 reduced polyethylene wear. However there is no published information regarding in vivo wear. Previous reports suggest that newly introduced materials which reduce in vitro polyethylene wear do not necessarily reduce in vivo polyethylene wear. To assist in the evaluation of the newly introduced material before widespread use, we established an in vivo polyethylene wear particle analysis for TKA. The aim of this study was to compare in vivo polyethylene wear particle generation between E1 and conventional polyethylene (ArCom) in TKA. A total of 34 knees undergoing TKA (17 each with ArCom or E1) were investigated. Except for the polyethylene insert material, the prostheses used for both groups were identical. Synovial fluid was obtained at a mean of 3.4 years (SD 1.3) postoperatively. The in vivo polyethylene wear particles were isolated from the synovial fluid using a previously validated method and examined by scanning electron microscopy.Aims
Methods
Our objective in this article is to test the hypothesis that
type 2 diabetes mellitus (T2DM) is a factor in the onset and progression
of osteoarthritis, and to characterise the quality of the articular
cartilage in an appropriate rat model. T2DM rats were obtained from the UC Davis group and compared
with control Lewis rats. The diabetic rats were sacrificed at ages
from six to 12 months, while control rats were sacrificed at six
months only. Osteoarthritis severity was determined via histology
in four knee quadrants using the OARSI scoring guide. Immunohistochemical
staining was also performed as a secondary form of osteoarthritic
analysis.Objectives
Methods
We attempted to characterise the biological quality
and regenerative potential of chondrocytes in osteochondritis dissecans
(OCD). Dissected fragments from ten patients with OCD of the knee
(mean age 27.8 years (16 to 49)) were harvested at arthroscopy.
A sample of cartilage from the intercondylar notch was taken from
the same joint and from the notch of ten patients with a traumatic
cartilage defect (mean age 31.6 years (19 to 52)). Chondrocytes
were extracted and subsequently cultured. Collagen types 1, 2, and
10 mRNA were quantified by polymerase chain reaction. Compared with
the notch chondrocytes, cells from the dissecate expressed similar
levels of collagen types 1 and 2 mRNA. The level of collagen type
10 message was 50 times lower after cell culture, indicating a loss
of hypertrophic cells or genes. The high viability, retained capacity
to differentiate and metabolic activity of the extracted cells suggests
preservation of the intrinsic repair capability of these dissecates.
Molecular analysis indicated a phenotypic modulation of the expanded
dissecate chondrocytes towards a normal phenotype. Our findings
suggest that cartilage taken from the dissecate can be reasonably
used as a cell source for chondrocyte implantation procedures.
This retrospective study evaluated the midterm clinical and radiographic outcomes of a second-generation total knee replacement system. In a multicentre consecutive series of 1512 patients, 1970 knees were treated with the PFC Sigma knee system (Depuy, Warsaw, Indiana). The patients were reviewed for functional outcome, and underwent independent radiographic evaluation at a mean follow-up of 7.3 years (5 to 10). A total of 40 knees (2%) required revision, 17 (0.9%) for infection. The incidence of osteolysis was 2.2%. The ten-year survival with revision for any cause other than infection as the endpoint was 97.2% (95% CI 95.4 to 99.1). The PFC Sigma knee system appears to provide excellent results in the medium term.
We prospectively examined the physical and imaging findings, including MRI, of 23 patients with spontaneous osteonecrosis of the knee after obtaining informed consent to acquire tissue specimens at surgery. There were four men and 19 women, with a mean age of 67.5 years (58 to 77). Plain radiographs were designated as stages 1, 2, 3 or 4 according to the classification of Koshino. Five knees were classified as stage 1, five as stage 2, seven as stage 3 and six as stage 4. The histological specimens were stained with haematoxylin and eosin and tetrachrome. In the early stages of the condition, a subchondral fracture was noted in the absence of any features of osteonecrosis, whereas in advanced stages, osteonecrotic lesions were confined to the area distal to the site of the fracture which showed impaired healing. In such cases, formation of cartilage and fibrous tissue, occurred indicating delayed or nonunion. These findings strongly suggest that the histopathology at each stage of spontaneous osteonecrosis is characterised by different types of repair reaction for subchondral fractures.
