Adenosine triphosphate (ATP) has been implicated as an autocrine/paracrine signal in the mechanotransduction pathway of chondrocytes. In this study, human chondrocytes in a 3D agarose scaffold were cultured with exogenous ATP in varying doses to determine its effect on extracellular matrix synthesis by the cells. Further experiments determined basal ATP release, ATP degradation and expression of P2Y1 and P2Y2 purinoreceptors by the cultured cell constructs. Human chondrocytes were obtained by enzymatic digestion of cartilage samples obtained at the time of total joint arthroplasty. The chondrocytes were cultured in a 3D agarose scaffold using standard tissue culture techniques. Various concentrations of exogenous ATP were added to the cultures, along with the radioisotopes to assess matrix synthesis. The cultures were harvested after a 24 hr incubation and radioisotope incorporation was determined by scintillation counting to determine proteoglycan ([35S]-sulfate) and collagen ([3H]-proline) synthesis, respectively. DNA content was determined by the Hoescht 33258 binding assay, and the proteoglycan and collagen synthesis were normalized to DNA content. Basal ATP release and degradation of exogenous ATP were determined by luciferase assay and luminometry. Expression of P2Y1 and P2Y2 purinoreceptors were determined by flow cytometry.Purpose
Method
This randomized clinical trial compares fixed- and mobile-bearing total knee prostheses in terms of the patients’ clinical outcome parameters (Knee Society Clinical Rating, WOMAC, SF-12), range of motion and performance during gait analysis for level-ground walking. Our results show no significant differences in the clinical outcomes and gait performance of the fixed- and mobile-bearing total knee arthroplasties. The purpose of this study was to compare the clinical outcomes and gait parameters of patients with a fixed-bearing or mobile-bearing total knee arthroplasty (TKA). Fifty-five patients were entered into a prospective, randomized clinical trial comparing fixed- versus mobile-bearing TKAs (Genesis II, Smith &
Nephew, Memphis, TN). From this patient population, fifteen fixed-bearing and fifteen mobile-bearing TKA patients were matched based on age, sex and BMI to undergo gait analysis. Patients performed trials of level-ground walking at a self-selected velocity while three-dimensional kinetic and kinematic data were collected. The fixed-bearing and mobile-bearing TKA patient groups were comparable regarding Knee Society Clinical Rating (181 ± 22 versus 171 ± 28), WOMAC scores (7 ± 5 versus 9 ± 12), SF-12 and range of motion (121° ± 11° versus 125° ± 6°). Patients with fixed- and mobile-bearing TKAs performed similarly in the gait analysis in terms of their velocity, percent weight acceptance in the operated versus the non-operated limb, peak flexion in stance and swing phases, the support moments and extension moments at the ankle, knee and hip. Decreased peak extension in the mid-stance and swing phases was observed in the operative limb versus the non-operative limb for both fixed- and mobile-bearing TKAs (P=0.02 and 0.04). Decreased peak extension was also observed during mid-stance and swing phases in the mobile-bearing TKAs versus the fixed-bearing TKAs (P=0.064 and 0.052). Fixed-bearing and mobile-bearing TKAs perform similarly in terms of their clinical outcome measures and the kinetics and kinematics of level-ground walking. Funding for this project obtained from Smith &
Nephew, Memphis, TN.
