The effect of angulation and overgrowth on ulnar variance in conservatively managed pediatric both bone forearm fractures

Both bone forearm fractures constitute 13.4% of pediatric fractures. While there are many studies with length differences in long bone fractures, studies on both bone forearm fractures are rare. The functional effect of ulnar variance on carpal bones of the distal radius and distal ulna in the wrist is known. Since the effect of elongation and angulation that may develop in the forearm bone after fracture on ulnar variance and wrist function is unknown, we aimed to evaluate the relationship of angulation and overgrowth on ulnar variance in pediatric both bone forearm fractures that healed at least one year after the fracture who were followed up conservatively. The study was conducted by retrospectively examining children aged 5-14 years who applied to Amasya University Sabuncuoğlu Şerefeddin Training and Research Hospital with both bone forearm fractures between January 1, 2018 and October 31, 2023. Range of movements were evaluated clinically. VAS scores, QuickDASH scores, MAYO wrist scores were evaluated and hand grip abilities were evaluated with a hand dynamometer. For patients with joint radius and ulna fractures from the shaft region to the metaphysis, regular bilateral forearm anterior-posterior (AP) and lateral, bilateral wrist posterior-anterior (PA) and lateral radiographs were evaluated. The difference between the angle of radius and angle of ulna called as radius-ulna angle. Radius length, ulna length, radial inclination, ulnar variance were measured and noted. Descriptive statistics were determined as mean±standard error. There is a statistical difference between the hand dynamometer score on fractured side and the normal side (p<0.000). VAS score is 1.34±0.25, MAYO wrist score is 77.95±0.83, QuickDASH score is 3.46±0.61. When wrist range of motion of the fractured side and the normal side were evaluated comparatively in the physical examination, a significant difference was detected (p<0.000). Although there was no statistical correlation between radius-ulna angle at reduction with ulnar variance (p=0.352), ulnar variance was statistically significant affected when radius-ulna angle was -7 degree and above with independent t test (p=0.049). In follow-up radiographs, there is approximately 1.8 mm increases in radius length, an approximately 1.6 mm extension in ulna length, an approximately 2.66 degree increase in radial inclination and a 0.7-1.1 cm negativity in ulnar variance compared to normal side. There is a linear relationship between radius length and ulna length with radial inclination (p<0.000). There is an inverse relationship between ulnar variance and radial inclination (p=0.021). While radiological changes do not affect wrist scoring, they do clinically cause changes in wrist functions. While the increase in radius length and ulna length increases radial inclination, it also negatively affects ulnar variance. Increasing the radius and ulna length indirectly makes ulnar variance negative.