Stress Distribution According to Center-Edge Angle in Dysplastic Hip and the Biomechanical Effect of Rotational Acetabular Osteotomy / 대한정형외과학회잡지

PURPOSE: The purpose of this study was to estimate the biomechanical effect of rotational acetabular osteotomy by analyzing the stress on the surface of the femoral head according to center-edge (CE) angle by computer simulation. MATERIALS AND METHODS: We performed computer simulation by simplifying the pelvis and femur to 3-dimensional flat stress. We analyzed the change of distribution of stress and the amount of deformation according to the degree of acetabular dysplasia, represented by the change of CE angle, by using a Finite element model (FEM). Stress and deformation were calculated in two cases that underwent rotational acetabular osteotomy. RESULTS: In the FEM model, the stress was 3.74 MPa at a CE angle of 30.and the deformation was 1.37 mm. The stress was 14 MPa at 15., 34.2 MPa at 0., and 82.4 MPa at -15. In a case of rotational acetabular osteotomy, the pre-operative and post-operative stresses were 26.1 MPa and 5.16 MPa, and the maximal deformations were 16.1 mm and 1.6 mm, respectively. CONCLUSION: As the severity of acetabular dysplasia increases, the stress concentration also increases. When the CE angle is below 0., a high concentration of stress develops. After rotational acetabular osteotomy, maximal stress was reduced to normal levels and sufficient stress distribution was achieved.

Restoration of Joint Space of the Knee After High Tibial Osteotomy

PURPOSE: The purpose of this study was to evaluate whether the medial joint space could be restored by HTO in osteoarthritic knee associated with varus deformity and to evaluate its clinical results. MATERIALS AND METHODS: HTO for medial gonarthrosis was performed in 65 knee joints of 59 patient. The median follow-up period was 36 months. The femoro-tibial angle(FTA) and joint space distance of medial and lateral compartment of the knee was measured on the weight-bearing antero-posterior plain radiogram. And the clinical results were evaluated by HSS knee score composed of pain, function, range of motion, muscle strength, flexion deformity and instability. RESULTS: Medial joint space distance was restored to 2.9 mm in average at postoperative 3 years from 1.8 mm in average preoperatively. Also the lateral joint space distance was maintained without decrease. FTA was corrected from varus 6.3 degree in average preoperatively to valgus 7.3 degree in average at three years postoperatively. HSS score was improved from 69.1 point in average preoperatively to 95 points in average at three years postoperatively. The group of increased joint space distance showed more improved HSS score and more corrected FTA than the unchanged group(p<0.05). When the change of HSS score was compared according to the postoperative FTA, the group, FTA was corrected 7 degree or more had more improved clinical results and more increased joint space distance(p<0.05). Complications were pain or tenderness on the fibular osteotomy site in seven knees, nonunion of fibular osteotomy in seven knee, transient peroneal paresis in four knees and delayed union of tibial osteotomy in one knee. CONCLUSION: At three years follow up after HTO, there was restoration of joint space of the medial compartment of the knee. Also we found the fact that the joint space widening was correlated with clinical improvement. These results suggest that the correction angle of valgus 7 degree or more may have better clinical outcomes.

Clinical Results of Anterior Cruciate Ligament Reconstruction: Bone-Paterllar-Tendon-Bone vs Hamstring Tendon Autograft

PURPOSE: To compare the clinical and radiologic results of the anterior cruciate ligament(ACL) recon- struction between bone-patellar tendon-bone autograft and doubled semitendinosus and gracilis autograft. MATERIALS AND METHODS: 45 patients out of 235 ACL reconstructions with bone-patellar tendon- bone(BPTB) autograft and 47 patients out of 178 ACL reconstructions with doubled semitendinosus and gracilis were included in this study. Average follow-up period were 19 months in BPTB autograft and 17 months in doubled semitendinosus and gracilis autograft. There were no differences in preoperative parameters(age, sex, instability). RESULTS: There were no significant differences between two groups with respect to functional result(Lysholm knee score), degree of laxity and range of motion at final follow-up. However, the parap- atellar complications, especially anterior knee pain after long distance walking or exercise, and quadriceps weakness were less occurred in doubled semitendinosus and gracilis autograft than in BPTB autograft. CONCLUSION: ACL reconstruction with doubled semitendinosus and gracilis autograft is a good alternative choice in reducing parapatellar complications and in achieving functional stability of knee joint.