Differences between Radiologic Angle & Real Angle of Distal Metatarsal Articular Surface Angle

Kim, Hyun Cheol; Chang, In Youb

Abstract

Selection of the surgical procedure for Hallux Valgus is decided after variable factors including radiologic indices were considered. Among them, congruency of the first metatarsophalangeal [MTP] joint is important factor to get the better prognosis. Articular surface angle of first metatarsal head [AAMH] has been used to substituted for first MTP joint congruency. But there had been questions whatever that the value of AAMH measured radiologically equal to real angle in surgical field. The purpose of this article is to compare clinically used radiologic angle of AAMH to real anatomical angle in patients operated by. From march to october 1998, among the 75 patients operated by surgical method (Proximal Chevron), measures anatomical AAMH of 25 volunteer at random. Average age was 46.4 yrs old, ratio of the sample is Right : Left = 9 : 16. The radiologic AAMH measured by AOFAS (American Orthopedic Foot and Ankle Society) research committee method 1992 in the weight bearing foot AP film. The actual AAMH is measured directly in the operative field. After the capsular incision had done, first metatarsal head was dislocated totally. K -wire was inserted to articular dome of the metatasal head from medial to lateral, The transverse axial plane of K -wire is parallel to plantigrade foot position. Afterthen, printed image was taken using portable image intensifier. Average radiologic value of metatarsal head was 16.8 degree, real value was 23.52 degree. In general, real angle was bigger than radiologic angle. In the 20% of cases, radiologic angle was bigger than real angle. With paired t -test, there was no correlations in each angles (p>0.01). Conclusion; The average real AAMH measured in surgical field was 23.1degree. There was no statistic correlations between the angles radiologically and anatomically. therefore, We conclude that the angle of distal metatarsal articular surface measured radiologically has not the clinical significance to know articular congruency. Consequently We suggested the three dimensional study to know the real angle of articular surface of first metatarsal head clinically as alternative method.