Effects of the Amount of Proximal Tibia Resection on the Bone Strength of Prepared Bone Surface: A FEM Study / 대한정형외과학회잡지

PURPOSE: We wanted to evaluate the mechanical strength of proximal tibia as resection distance increased from the joint surface. MATERIALS AND METHODS: We obtained the CT images of twenty knee osteoarthritis patients undergoing total knee arthroplasty. The finite element models were created based on the computed tomography images. The 8-node hexahedron element was made from BIONIX(TM) (CANTIBio. Co, Suwon, Korea), which is automatic mesh generation software program. The finite element model of the proximal tibia was resected at 6 mm, 8 mm, 10 mm, 12 mm, 15 mm and 18 mm from the lateral joint surface. A 1% strain rate was applied to a model by using HyperMesh(TM) software (Altair Engineering. Inc, Seattle, USA). The ultimate stress was calculated from the finite element analysis with using ANSYS 9.0 (ANSYS. Inc, Orlando, USA). RESULTS: The mean ultimate stress was 906.84 MPa, 877.22 MPa, 895.93 Mpa, 852.70 MPa, 742.90 Mpa and 585.51 Mpa at the 6 mm, 8 mm, 10 mm, 12 mm, 15 mm and 18 mm resection levels. As compare to the 6 mm resection level, the bone strengths at 15 mm and 18 mm were decreased with statistical significance (15 mm: p=0.005, 18 mm: p=0.000). CONCLUSION: The ultimate stress was decreased as the resection distance increased from the joint surface. But within a 12 mm resection distance from the lateral condyle articular surface of the tibia, the ultimate stress was not significantly decreased (p>0.05).

The Study for the Velocity Measurement of the Horizontal Saccadic Eye Movement

Saccadic eye movement may be difined entirely on the basis of velocity-amplitude characteristics. Despite the obvious importance of saccadic peak velocity measurements, there is lack of agreement about saccadic velocity-amplitude relationships in general and particularly with regard to the direction of movement. The variability of the results is attributed mostly to different recording techniques used and partly to the sample size. The aim of this study is to investigate the effect of saccadic direction for the determination of their possible influence upon the horizontal saccadic peak velocity. Therefore, six basic patterns of horizontal saccadic movement were determined and the direction and velocity of these basic patterns of the angular distance of 10 degrees were recorded and discussed. The experimental apparatus consisted of Biometrics Eye Movement Monitors, target function generators, oscillographic recorders and the other fixation devices. The experimental subjects were three healthy Korean adults. All experiments had been performed in the dark room for 4 weeks. The position and peak velocity of saccadic eye movement in the records were carefully observed and the data were analyzed statistically for significant change with the use of t-test at the 5 per cent level and the main results are as follows: 1. In the horizontal saccadic eye movement in the angular distance of 10 degrees, the production rate of undershoot or corrective movement is low and most of the saccadic eye movement are normal. 2. The mean of the saccadic peak velocity is 295.6 deg/sec in the angular distance of 10 degrees. 3. The mean horizontal saccadic peak velocity is faster in the nasal direction, as compared with the temporal direction, but the difference is not statistically significant. 4. The mean saccadic peak velocity is greater in the nasal than in the temporal direction among the velocities of the centering, decentering and symmetry but the difference is not statistically significant. 5. The analysis of the results showed that the mean horizontal saccadic peak velocity has no statistically significant difference between the nasal and the temporal direction in the angular distance of 10 degrees. Author feels that the methods and results of this study may be useful tools in the diagnosis and research of eye disease related to the nervous system and that further study to establish the standard data of saccadic peak velocity should be performed at the various angular distances.

Glaucomatocyclitic Crisis

The glaucomatocyclitic crisis was first described by Posner and Schlossman in 1948, and belongs to the classification of secondary open angle glaucoma. It is unilateral and recurrent. and characterized by minimal inflammatory signs and symptoms. The inflammation may be confined to the trabecular mesh work. The facility of outflow reduced while attacks last from a few hours to over 2 weeks. Etiopathogenic nature of glaucomatocyclitic crisis is not clear but recently the role of allergy is suggested in this disease entity. A 35 year old man was found to have a glaucomatocyclitic crisis in his right eye that was treated with systemic diamox and topical corticosteroid.

Three Cases of Papillomas Occurring on the Outer Eye

Papilloma is a benign epithelial tumor and may be divided etiologically into two types: viral infectious and neoplastic; histologically the two types are indistinguishable. In the field of ophthalmology, Norris reported for the first time in 1879 that papilloma begins on the bulbar conjunctiva and spreads toward the cornea. Since then, many other cases of papilloma have been reported and these reports showed that it can occur on any portion of the epithelium of the external eye and has a predilection for sites where the epithelium undergoes a transition. We have seen three patients with papillomas: a 6 year old girl with a papilloma on the caruncle; a 29 year old man, on the lower fornix; and a 42 year old woman, on the limbus. The caruncle and lower fornix papillomas were asymptomatic; the limbal papilloma was accompanied by foreign body sensation, epiphora, photophobia, and mild visual disturbance. On examination, the lesion on the caruncle was grayish-red; the surface was smooth with diffuse small red spots The lesion on the lower fornix was bright red, smooth surfaced, pedunculated, strawberry-like in appearance and showed papillary vascular proliferations. The margins of the limbal lesion extended to bulbar conjunctiva and cornea and the masswas firmly adherent to the cornea. The strawberry-like mass was grayish-white in color, hard, slightly elevated and showed papillary vascular proliferations. We feel that the papillomas on caruncle and lower fornix are viral infectious type and the one on the limbus is neoplastic type, based on the site of lesion, clinical symptoms and signs, and the age of the patient. The lesions of the above cases were removed by simple excisional biopsy and the one on the limbus also received post-excisional radiation treatment with Strontium 90. There has been no sign of complication in the four months of follow-up on the caruncle papilloma and two months of follow-up on the lower fornix and limbal papilloma.