Does Early Conversion to Below-elbow Casting for Pediatric Diaphyseal Both-bone Forearm Fractures Adversely Affect Patient-reported Outcomes and ROM?
Authors: Musters Linde , Roth Kasper C. , Diederix Leon W. , Edomskis Pim P. , Benner Joyce L. , Reijman Max , Eygendaal Denise , Colaris Joost W. 
Published: May 2024

Background
For distal forearm fractures in children, it has been shown that a below-elbow cast is an adequate treatment that overcomes the discomfort of an above-elbow cast and unnecessary immobilization of the elbow. For reduced diaphyseal both-bone forearm fractures, our previous randomized controlled trial (RCT)—which compared an above-elbow cast with early conversion to a below-elbow cast—revealed no differences in the risk of redisplacement or functional outcomes at short-term follow-up. Although studies with a longer follow-up after diaphyseal both-bone forearm fractures in children are scarce, they are essential, as growth might affect the outcome.

Questions/purposes
In this secondary analysis of an earlier RCT, we asked: (1) Does early conversion from an above-elbow to a below-elbow cast in children with reduced, stable diaphyseal forearm fractures result in worse clinical and radiological outcome? (2) Does a malunion result in inferior clinical outcomes at 7.5 years of follow-up?

Methods
In this study, we evaluated children at a minimum of 5 years of follow-up who were included in a previous RCT. The median (range) duration of follow-up was 7.5 years (5.2 to 9.9). The patients for this RCT were included from the emergency departments of four different urban hospitals. Between January 2006 and August 2010, we treated 128 patients for reduced diaphyseal both-bone forearm fractures. All 128 patients were eligible; 24% (31) were excluded because they were lost before the minimum study follow-up or had incomplete datasets, leaving 76% (97) for secondary analysis. The loss in the follow-up group was comparable to the included population. Eligible patients were invited for secondary functional and radiographic assessment. The primary outcome was the difference in forearm rotation compared with the uninjured contralateral arm. Secondary outcomes were the ABILHAND-kids and QuickDASH questionnaire, loss of flexion and extension of the elbow and wrist compared with the contralateral forearm, JAMAR grip strength ratio, and radiological assessment of residual deformity. The study was not blinded regarding the children, parents, and clinicians.

Results
At 7.5-year follow-up, there were no differences in ABILHAND-kids questionnaire score (above-elbow cast: 41 ± 2.4 versus above/below-elbow cast: 41.7 ± 0.7, mean difference -0.7 [95% confidence interval (CI) -1.4 to 0.04]; p = 0.06), QuickDASH (above-elbow cast: 5.8 ± 9.6 versus 2.9 ± 6.0 for above-/below-elbow cast, mean difference 2.9 [95% CI -0.5 to 6.2]; p = 0.92), and grip strength (0.9 ± 0.2 for above-elbow cast versus 1 ± 0.2 for above/below-elbow cast, mean difference -0.04 [95% CI -1 to 0.03]; p = 0.24). Functional outcomes showed no difference (loss of forearm rotation: above-elbow cast 7.9 ± 17.7 versus 4.1 ± 6.9 for above-/below-elbow cast, mean difference 3.8 [95% CI -1.7 to 9.4]; p = 0.47; arc of motion: above-elbow cast 152° ± 21° versus 155° ± 11° for the above/below-elbow cast group, mean difference -2.5 [95% CI -9.3 to -4.4]; p = 0.17; loss of wrist flexion-extension: above-elbow cast group 1.0° ± 5.0° versus 0.6° ± 4.2° for above/below-elbow cast, mean difference 0.4° [95% CI -1.5° to 2.2°]; p = 0.69). The secondary follow-up showed improvement in forearm rotation in both groups compared with the rotation at 7 months. For radiographical analysis, the only difference was in AP ulna (above-elbow cast: 6° ± 3° versus above/below-elbow cast: 5° ± 2°, mean difference 1.8° [0.7° to 3°]; p = 0.003), although this is likely not clinically relevant. There were no differences in the other parameters. Thirteen patients with persistent malunion at 7-month follow-up showed no clinically relevant differences in functional outcomes at 7.5-year follow-up compared with children without malunion. The loss of forearm rotation was 5.5ׄ° ± 9.1° for the malunion group compared with 6.0° ± 13.9° in the no malunion group, with a mean difference of 0.4 (95% CI of -7.5 to 8.4; p = 0.92).

Conclusion
In light of these results, we suggest that surgeons perform an early conversion to a below-elbow cast for reduced diaphyseal both-bone forearm fractures in children. This study shows that even in patients with secondary fracture displacement, remodeling occurred. And even in persistent malunion, these patients mostly showed good-to-excellent final results. Future studies, such as a meta-analysis or a large, prospective observational study, would help to establish the influence of skeletal age, sex, and the severity and direction of malunion angulation of both the radius and ulna on clinical result. Furthermore, a similar systematic review could prove beneficial in clarifying the acceptable angulation for pediatric lower extremity fractures.

Level of Evidence
Level I, therapeutic study.