MEASURING HALLUX-VALGUS - A COMPARISON OF CONVENTIONAL RADIOGRAPHY AND CLINICAL-PARAMETERS WITH REGARD TO MEASUREMENT ACCURACY

To assess the repeatability and error of conventional x-ray measuremen ts, intra- and interobserver evaluations of measurement accuracy were done on 20 preoperative and 40 postoperative (20 chevron and 20 proxim al osteotomy) x-rays of hallux valgus patients. Standard x-rays showed an average interobserver error of measurement of 6.4 degrees for the hallux valgus angle, 5.4 degrees for the intermetatarsal angle, and 2. 0 mm for the intermetatarsal distance. The intraobserver error did not differ greatly. The repeatability and error of two clinical measureme nts, ball circumference, and dorsal to plantar range of motion of the first metatarsophalangeal joint were evaluated for 20 healthy voluntee rs. The ball circumference had an average measurement error of 1.1 cm, whereas the dorsal and plantar range of motion of the great toe had a n average measurement error of 12 degrees in dorsiflexion and 16 degre es in plantarflexion, In both clinical and radiographic parameters, li near measurements were more accurate than angular measurements. Althou gh x-rays are of value in hallux valgus surgery, standard x-rays are l ess accurate than previously assumed. Small changes produced by osteot omies may be hidden by the postoperative measurement error. The result s of hallux valgus surgery should primarily be evaluated clinically. W hen clinical and radiological evaluations are made, linear measurement s may be preferable.