ABSTRACT
BACKGROUND: Although it has been found in many studies that three-dimensional finite element analysis can be used in the study of knee joint biomechanics, there are few researches on different defect areas of medial condyle cartilage of the femur. OBJECTIVE: To analyze the stress change trend of perimeter articular cartilage before and after the occurrence of different defect areas of medial femoral condyle cartilage, providing biomechanical data for patients with knee medial femoral condyle cartilage defect. METHODS: One normal adult had been selected to establish a three-dimensional finite element model. Material mechanical properties were input to Abaques software with divided grid model. After controlling boundary condition with mechanical load, structural nonlinear finite element was calculated. First, the load stress distribution of knee cartilage and meniscus was observed under normal stress. Articular cartilage stress distribution was observed with load conditions in different defects (0, 6, 8, 10, 12, 14, 16, 18 and 20 mm) of medial femoral condyle. The stress changes on the cartilage were analyzed during the defect of medial femoral condyle. This study was approved by the Ethics Committee of First Affiliated Hospital of Kunming Medical University. The volunteer signed the informed consent. RESULTS AND CONCLUSION: (1) Material properties, boundary conditions and the introduction of loads were defined successfully. The stress cloud chart and its stress data were obtained from different diameter defects of cartilage in medial condyle of knee joint. According to statistical analysis, the stress on the femoral condyle and tibial plateau cartilage had significant changes compared with no defects when the medial femoral condyle cartilage had defects of 10 mm (area 0. 78 cm2) and 12 mm (area 1. 13 cm2). (2) The stress change trend of the cartilage of the medial condyle of the knee joint under the condition of different diameter defects was calculated based on the analysis of the application of three-dimensional finite element method. (3) Results suggest that the defect with the diameter of 10 mm (area 0. 78 cm2) of medial femoral condyle may be the minimum diameter advised for operation intervention of cartilage repair.
ABSTRACT
Objective To explore the consistency of knee articular cartilage defect area by magnetic resonance imaging (MRI)and arthroscopy.Methods Thirty-six patients (36 knees)with knee cartilage lesions were collected in our study.The defect area meas-urement of knee articular cartilage by MRI and arthroscopy was compared.Results A total of 92 lesions were detected by both MRI and arthroscopy with an average of 2.6 defects per knee.Preoperative MRI resultes demonstrated the mean defect area per knee was (1.9±1.5)cm2 ,while arthroscopic measurement after debridement indicated the mean defect area per knee was (2.9±2.6)cm2 , which had significant difference(P <0.001).The area measured by MRI was less than that by arthroscopy,and the mean difference was (1.7 ± 1.1)cm2 .The mean area measured by MRI was 70.1% of that by arthroscopy.Conclusion Arthroscopy and MR have good consistency in the number of articular cartilage defect lesions .MRI can reflect the knee articular cartilage defect area directly or indirectly,and be capable of accurate positioning and qualitative diagnosis.
ABSTRACT
Calvarial bone grafting in craniomaxillofacial trauma and facial reconstructive surgery is now widely recognized and accepted as a standard procedure. One of the commonly reported problems of calvarial bone graft is the contour defect caused by partial resorption of the graft. But, there are few reports that discuss the fate of the calvarial bone graft based on the quantitative data. In this article, the changes of grafted calvarial bone were evaluated using 3-dimensional computed tomography(CT). 9 patients were observed with the CT scans at 2mm thickness immediately after operation and at the time of last follow-up. The area of the bone defect was segmented on the 3-dimensional CT image and calculated by AnalyzeDirect 5.0 software. The immediate postoperative bone defect area of the recipient site and the donor site were 612.9mm2 and 441.5mm2, respectively, which became 1028.1mm2 and 268.8mm2, respectively at the last follow-up. In conclusion, the bone defect area was less increased on the donor site of calvarial bone graft than on the recipient site. And the CT scan is a valuable imaging method to assess and follow-up the clinical outcome of calvarial bone grafting.