Robotics Bellemans, J.
Total Knee Arthroplasty
Book Chapter
Today there is growing evidence that performing total knee arthroplasty using computer navigation can lead to a more accurate surgical positioning of the components and subsequent alignment of the ...knee prosthesis, compared with when a conventional operating technique without computer assistance and navigation is used. These computer navigation systems are readily available and are being used more and more in daily practice.
The use of robotic technology could theoretically take this accuracy one level further, since it uses navigation in combination with ultimate mechanical precision, which could eliminate or reduce the inevitable margin of error during mechanical preparation of the bony cuts by the surgeon. In this chapter we report the experiences gained so far with robotic technology in knee arthroplasty surgery.
An Experimental Model for Kinematic Analysis of the Knee Victor, Jan, MD, PhD; Van Glabbeek, Francis, MD, PhD; Somville, Johan, MD, Ir, PhD ...
Journal of bone and joint surgery. American volume,
2009, Volume:
91
Journal Article
The goal of reducing the length of a patient's hospital stay after orthopaedic surgery has recently gained much interest from surgeons and hospital administrators. The influence of hospital stay ...reduction on qualitative outcome is not always documented. The purpose of this study was to investigate this relationship in more detail. We report our experience with patients undergoing total knee arthroplasty. In 2000, an in-hospital clinical pathway for patients undergoing total knee arthroplasty was instituted at the University Hospitals Pellenberg, Belgium. We evaluated this pathway in 103 patients by using a pre-experimental, interrupted, time-series design. This pathway significantly decreased length of stay by 33% without negatively affecting functional outcomes during hospitalisation. In further research also the long-term effects have to be studied.
Limb threatening arterial occlusion during total hip or knee arthroplasty is an uncommon complication. The authors present two cases of thrombosis of the common femoral artery that occurred following ...and during total hip arthroplasty respectively. Acute thrombectomy was performed in both patients within 3-4 hours after the diagnosis. Both patients permanently kept some numbness over the foot and slight weakness in the extensors. With a delayed diagnosis such lesion may have lead to the loss of their limb. This underlines the absolute need for regular control of the arterial supply, sensory and motor conditions following joint arthroplasty during the first 24 hours following surgery.
Total knee arthroplasty requires accurate preparation of the bone surfaces to maximize bone implant contact area in cementless surgery and to obtain proper joint kinematics and ligament balancing. ...Robots can make the cuts with the necessary high precision. The purpose of this article is threefold: to propose an alternative method for intraoperative registration using an in-tramedullary rod and an alternative method for force control using the hybrid force-velocity control scheme; to demonstrate that the accuracy and the surface flatness of the cuts machined by a robot are better than in a conventional operation; and to monitor the machining process and to try to derive some information about the local bone quality from it. The results of the laboratory study are promising: the surface flatness of the tibial plateau, calculated using a least squares method, is 0.1-0.2 mm, which is significantly better than in conventional surgery; and the high angular accuracy of the robot allows the bone cuts to be located precisely. Further, an exponential relation between milling forces and local bone density was established, so measurements of the milling forces can provide the surgeon with on -line information about the local bone quality.
Fluorine-18 fluorodeoxyglucose positron emission tomography (FDG-PET), technetium-99m hexamethylpropylene amine oxime (HMPAO)-labelled white blood cell (WBC) scintigraphy and bone scintigraphy were ...used in the evaluation of total knee arthroplasties (TKAs). We prospectively included 21 patients who had a three-phase bone scan for exclusion of infection of TKAs. Four hours after injection of 185 MBq 99mTc-HMPAO-labelled WBCs, planar and single-photon emission tomographic (SPET) imaging was performed. Planar imaging was repeated at 24 h p.i. Consecutively images of the knees were obtained with a dedicated PET system 60 min following the injection of 370 MBq of FDG. Focal tracer uptake was scored on SPET and PET visually (0=no uptake, 4=intense uptake). In addition, SUV (standardised uptake value) per voxel was calculated from attenuation-corrected PET images using the MLAA algorithm. Focal uptake at the bone-prosthesis interface was used as the criterion for infection before and after correlation with the third phase of the bone scan. Final diagnosis was based on operative findings, culture and clinical outcome. In the infected TKAs, the WBC scan showed focal activity of grade 2 (n=2), 3 (n=l) or 4 (n=2). PET scan revealed focal activity of grade 4 (n=5) or 3 (n=1). WBC scan alone had a specificity for infection of 53% positive predictive value (PPV) 42%, sensitivity 100%, compared with 73% for PET scan (PPV 60%, sensitivity 100%). Considering only lesions at the bone-prosthesis interface that were also present on the third phase of the bone scan, we found a specificity of 93% (PPV 83%) for WBC scan. Using these criteria, a specificity of 80% (PPV 67%) was obtained for PET scan. Two out of three false-positive PET scans were due to loosening of the TKA. It is concluded that WBC scintigraphy in combination with bone scintigraphy has a high specificity in the detection of infected TKAs. FDG-PET seems to offer no additional benefit.
The High-Performance Knee Ries, M. D.; Bellemans, J.; Victor, J.
Total Knee Arthroplasty
Book Chapter
Although total knee arthroplasty is effective in relieving knee pain and improving ambulatory function, the kinematics after knee replacement are quite different from those of the normal knee. During ...flexion of the normal knee, the lateral femoral condyle moves posteriorly, causing femoral external rotation. After knee replacement “paradoxical” motion typically occurs. The femur is displaced posteriorly during extension and moves anteriorly as the knee flexes. The cam-and-post mechanism of a posterior cruciate-substituting knee design limits anterior femoral translation so that the kinematics are less abnormal than with a posterior cruciate-retaining design. Additional modifications in the conformity of each tibial plateau and the cam-and-post geometry can further guide roll-back of the lateral more than the medial femoral condyle, causing femoral external rotation during knee flexion. Guided motion designs that reproduce more normal knee kinematics may result in improved range of motion and knee function following total knee arthroplasty.
•The geothermal brines proves to be corrosive to the tested materials.•Carbon steel demonstrates high uniform corrosion rates.•An iron carbonate layer is formed on the carbon steel samples.•Stainless ...steel and duplex steel are susceptible to localised forms of corrosion.•Experiments testing stress corrosion cracking or in situ experiments could be useful.
Geothermal energy is an interesting alternative to polluting fossil energy sources. Therefore, in Belgium, two wells have been drilled for a deep geothermal power plant. However, the environment to which the installations are exposed is challenging. The geothermal brine has 165 g/l total dissolved solids (of which 90% are sodium and chlorine) and the production temperature can be up to 130 °C. To assess their suitability to be used in a geothermal power plant, the corrosivity of the artificial brine to three common construction materials was investigated with exposure and electrochemical tests. The metals under consideration are a low-alloyed carbon steel (S235JR), an austenitic stainless steel (UNS S31603) and a duplex stainless steel (UNS S31803). The carbon steel, that was found to corrode uniformly, could be considered as a constructional material if a sufficient wall thickness is chosen. The austenitic stainless steel and the duplex stainless steel demonstrate very low uniform corrosion rates. They are however susceptible to pitting and crevice corrosion. To guarantee safe operation of the geothermal power plant, the susceptibility of the alloys to stress corrosion cracking should be tested and in situ experiments should be performed.
