We performed a CT-based computer simulation study
to determine how the relationship between any inbuilt posterior
slope in the proximal tibial osteotomy and cutting jig rotational
orientation errors affect tibial component alignment in total knee
replacement. Four different posterior slopes (3°, 5°, 7° and 10°),
each with a rotational error of 5°, 10°, 15°, 20°, 25° or 30°, were
simulated. Tibial cutting block malalignment of 20° of external
rotation can produce varus malalignment of 2.4° and 3.5° with a
7° and a 10° sloped cutting jig, respectively. Care must be taken in
orientating the cutting jig in the sagittal plane when making a
posterior sloped proximal tibial osteotomy in total knee replacement. Cite this article:
The midcortical line, the midline between the anterior and the posterior cortical walls has been reported as an intraoperative reference guide for reproducing the true femoral anteversion in cross-sectional computed tomography (CT) image study but we suspected that the version of the midcortical line on the cutting surface is different from that on the axial image. The three-dimensional (3D) CT-based preoperative planning software for THA enabled us to evaluate the cut surface of the femoral neck osteotomy. When we planned the straight non-anatomic stem placement in 20° of anteversion, we noticed that the line connecting the trochanteric fossa and the middle of the medial cortex of the femoral neck (T line) was coincident with the component torsion in almost all cases except those involving secondary osteoarthritis of the hip. Therefore we hypothesised that the T-line would provide an accurate reference guide for anteversion of the femoral component in THA. We performed this study to answer the question: which is the better intraoperative reference guide for reproducing the true femoral anteversion, the midcortical line or the T line? The institutional review board allowed a retrospective review of CT images of 33 normal femora (33 patients) in our CT database. We performed virtual THA using the non-anatomic straight stem on the 3D CT-based preoperative planning software at the two different cutting heights of 10mm or 15mm above the lesser trochanter. The anteversion of the stem implanted parallel to the T line or the midcortical line was measured. The true femoral neck anteversion was measured using the single CT slice method reported by Sugano.Introduction
Materials and methods
Combined multi-detector row CT (MD-CT) pulmonary angiography (CTPA) and lower extremity venography (CTV) is an effective method for detection of pulmonary embolism (PE) and deep vein thrombosis (DVT). However, the usefulness of this method after total knee arthroplasty (TKA) has not been reported. The aim of this study is to evaluate our screening program in the management of thromboembolism. Over a 1.5-year period, 30 patients with primary TKA were examined using an MD-CT (Lightspeed ultra 16.GE) before and 7th day after operation. 25 seconds after intravenous administration of 320ml of contrast material, CTPA was performed with 1.25-mm collimation and CTV from the iliac crest to the ankles was done with 0.625-mm collimation 165 seconds after contrastmaterial injection. The mean age of the patients was 72.2 (53–80). Twenty patients had osteoarthritis, nine had rheumatoid arthritis and one osteonecrosis. All patients were received 4 weeks of warfarin therapy and prophylaxis. PE was observed in A1+2, A3, A6, A9, A10 area. PE was most frequently detected in A10 area of pulmonary artery (6/30). While, DVT was detected in only popliteal vein (6/30). The incidence of PE was 30% (9/30)and DVT 20% (6/30). Both PE and DVT were observed in 3 patients, the incidence was 10% (3/30). Combined CTPA and CTV is a safe and accurate diagnotic method for detecting PE and DVT after TKA, and the ability to directly visualize emboli of this system is effective as therapeutic tool.
