Measurement of the Cement Thicknessaround the Femoral Stemin THRA: CAD Data Analysis Obtained from 3D Scanner / 대한정형외과학회잡지

PURPOSE: To measure the cement mantle thickness that developed from a rotation of the femoral stem in virtual space made by the broach. MATERIALS AND METHODS: The C stem and Versys stem of the subjects enrolled in this study were examined. A C250/400VZ(Steinbichler Co. Germany) and S/W: Geomagic & CATIA V5 was used to examine the three-dimensional configurations. The axial images were acquired after neutral placement of the femoral stem, horizontal rotation, coronal tilting, and a combination of both. The thickness was measured from the distance between the outer surface of the femoral stem and the closest vertex in the outer contour of the broach in cross-sectional images. RESULTS: The distance was <1 mm at the horizontal rotation of 3 degrees in the C stem, and at 5 degrees in the Versys stem. The distance was <1 mm at varus of 0.25 degrees in the C stem, and touched at 0.8 degrees. In the case of the Versys stem, the femoral stem touched at a varus of 1 degree. A combination of both horizontal and pivot rotation made the distance <1 mm at rotation of all angles. CONCLUSION: It might be necessary to develop a new instrument for the accurate insertion of the femoral stem along the broached space or to modify the stem design to stand against the change in the femoral stem position in the broached space.

A Predictive Method for the Femoral Head Necrosis by the Observation of the Bleeding from the Cannulated Screw in Patients of the Femoral Neck Fractures / 대한정형외과학회잡지

PURPOSE: The aim of this study was to examine the validity of using cannulated screws as a method for predicting avascular necrosis of the femoral head after a fixation of fractures in patients with femoral neck fractures. MATERIALS AND METHODS: Between March 1999 and January 2001, 44 patients with a femoral neck fracture that had been fixed with cannulated screws were enrolled in this study. The follow up period was more than 25 months and the mean age of the patients was 51 years (range, 18 to 76 year). Blood drainage in the holes of the screw head was checked. There were 38 cases in the bleeding group, and 6 cases in the non-bleeding group. The development of head necrosis was evaluated using plain radiography. The validity of the relationship between the two groups and head necrosis was evaluated by the sensitivity, specificity, the positive predictive value, and the negative predictive value. RESULTS: An avascular necrosis of the femoral head developed in 7 cases (16%). Only one of the 38 patients in the bleeding group developed head necrosis (2.6%). However, all those in the non-bleeding group developed head necrosis (100%). The sensitivity was 86%, the specificity was 100%, the positive predictive value was 100%, and the negative predictive value was 97%. CONCLUSION: Bleeding from holes in the cannulated screws is a simple and accurate perfusion assessment for predicting the development of an avascular necrosis of the femoral head after a femoral neck fracture.

Recovery of Motion Fraction and Shoulder Function ofter Operative Treatment of Shoulder Instability / 대한정형외과학회잡지

PURPOSE: We expected the motion fraction could be checked, with simple radiographic examination, according to the guide-line of fluoroscopic technique, and recovery of the function also could be correlated with the improvement of the motion fraction. MATERIALS AND METHODS: We measured the motion fraction of the glenohumeral and scapulothoracic movement using fluoroscope in 30-degree intervals of arm elevation in the scapular plane. The ratio of glenohumeral to scapulothoracic movement (thetaGH/thetaST) was 1.6 for the full range of motion in scapular plane. During arm elevation, scapular tilting from the coronal plane was decreased from 42 degrees to 20 degrees tilting as well as internal rotation (scapular extension). We also measured the motion fraction (thetaGH/thetaST) and functional recovery of the shoulder in 11 patients after operative treatment of the shoulder instability in 15 patients from December 1996 to August 1997. RESULTS: We could find out a significant correlation between the recovery of motion fraction and shoulder function. These results would be applied in planing rehabilitation program after treatment of the shoulder instability. CONCLUSIONS: The measuring technique of glenohumeral to scapulothoracic movement (thetaGH/thetaST) with fluoroscopy could be applied to the simple radiographic measurement at the out-patient clinic in order to identify the pathology and recovery of shoulder motion after treatment

Patella Position in the Normal Knee Joint / 대한정형외과학회잡지

Patella position in the normal knee jolnt has been discussed by many authors such as Boon-Itt 1930, Blumensaat 1938, and Insall 1971. But measure with Boon-Itt's method was so complicated and with Blumensaat's was denied by others due to inefficacy. Insall suggested more simple and clinically applicable method that was based on the fact that patellar tendon is inelastic. Now, we measured 100 healthy Korean knee accordlng to Insall's method. The following results were obtained in the study, 1. The length of the patellar tendon is 4.45 In males, 4.08 In females, and 4.26±0.40 cm. in average. (p<0.001) 2. The length of the patella is 4.51 in males, 4.09 In females, 4.36±0.40 cm. in average. (p<0.001) 3. The length of the patellar tendon (LT) and the dlagonal length of the pattella (LP) are almost same (LT: LP is 0.99 in both males and females, 98% of normal knees are contained within the difference of +20%). Difference above this limit may mean high-riding patella. 4. Blumensaats line on the distal femur doesnt pass the lower pole of the patella but the Iine passes 1 cm. below it in average. 5. The length of the patella (LP) and of the width of the femoral condyles at Blumensaat's line (WCBL) are almost same. When LP is markedly decreased in comparison with WCBL, this case may suggest hypoplasia of the patella. 6. Height of insertion of the patellar tendon (Hl) dlffers among various indlviduals. Its length is cllnically not so significant.