RESUMO
BACKGROUND: Headless compression screws have been used for arthrodesis of the distal interphalangeal joint with good clinical results. However, some distal phalanges are too small, thus precluding their use, or increasing complication rates. METHODS: In order to validate our digital measurements, radiographs of five cadaveric hands were obtained. The distal phalanges of these fingers were measured using our institution's digital radiograph software. The cadavers were then dissected, and the actual phalanges were measured to confirm the accuracy of the digital measurements; 200 consecutive hand radiographs were then measured to obtain average width and heights of the narrowest measurements of the distal phalanx of each finger. Subgroup analysis of each finger for age and gender was completed. RESULTS AND CONCLUSIONS: Females were routinely smaller than their male counterparts. No age-related differences were seen. A substantial number of fingers were found to be too small to allow for use of headless compression screws; 42 % of small finger distal phalanges are too small to accommodate 2.8-mm threads, and that number increases to 81 % with 3.2-mm threads and 97 % with 3.5-mm threads. Few distal phalanges, regardless of which finger, are large enough to accommodate 3.5-mm-diameter threads; 22% of female ring finger distal phalanges are smaller than 2.8 mm, and 66 % of ring fingers are smaller than 3.2 mm. Based on our measurements, a surprising number of distal phalanges are smaller than the trailing thread diameter of commonly commercially available headless screws. Care must be taken in selecting implants for distal interphalangeal (DIP) fusion.
RESUMO
STUDY DESIGN: This was a retrospective review of neuromuscular scoliosis radiographs evaluating interobserver and intra-observer error for a novel method of transverse plane pelvic obliquity. OBJECTIVES: To evaluate the utility of a previously described method by Lucas et al. of determining transverse plane pelvic obliquity using standard radiographs in patients with cerebral palsy and neuromuscular scoliosis. SUMMARY OF BACKGROUND DATA: Evaluation of pelvic obliquity in the transverse plane has not been thoroughly studied. The pelvis has been noted to function as intercalary vertebra in neuromuscular scoliosis, resulting in marked obliquity in all 3 planes. METHODS: Forty radiographs were chosen from 10 patients with cerebral palsy and neuromuscular scoliosis who had had a posterior spine arthrodesis and Galveston spino-pelvic fixation. Four observers independently examined the radiographs at different levels of training on 2 dates 1 week apart. Measurements recorded by each observer were described by Lucas et al.: E (the distance measured on lateral radiographs between the ilium at the inferior part of the sacro-iliac joint and the lateral edge of the anterior superior iliac spine), FR and FL (the coronal plane linear distance between the same 2 landmarks, measured from a posteroanterior radiograph, where F was measured for both the left (FL) and right (FR) sides of the pelvis, respectively), and ß (the transverse plane rotation of the pelvis). Reproducibility of the measurements were analyzed using the concordance correlation coefficient (CCC). A CCC of 0.80 or higher was considered excellent agreement. RESULTS: The CCC between the first and second sets of measurements was lowest for E and highest for the calculated ß, although none of the CCC calculations was statistically significant, demonstrating poor agreement. CONCLUSIONS: The ability to reliably measure and calculate the degree of transverse plane rotation by radiographs in cerebral palsy patients with spino-pelvic deformity by the method described by Lucas et al. is poor, likely because of difficulty in consistently identify pelvic landmarks.
