Introduction. Overlengthening of a radial head implant has been associated with less than optimal clinical outcomes and capitellar erosions. The purpose of this study was to identify which factors, both clinical and radiological, have influenced the clinical results in our series. Material and methods. Analytical study of a sample of 31 patients between 2005 and 2017 with an average follow-up of 5 years.Analysis of qualitative variables of age, sex, type of lesion and type of treatment used and analysis of the lenght of the implant by means of radiological measurements (implant and proximal margin of the lesser sigmoid notch/ lateral ulnohumeral angle) by independent evaluators with the updated results on scales of MEPS and DASH assessment and mobility ranges explored to the patient. Results. No significant differences depending on the type of lesion nor on the type of treatment were found. Implant length was aligned with the proximal margin of the lesser sigmoid notch in 16 cases, was higher in 12 (mean 3 mm, SD 1.5) and inferior in 3 (mean 3.4 mm, SD 1.7). The lateral ulnohumeral joint opening angle was increased an average range of 2,2º and this has shown to have a significant correlation with a reduction in the range of mobility for flexion and supination (p<0,05). Conclusions. An overlengthening or shortening up to 3 mm has not shown to alter the clinical results in our series, while an excessive lateral ulnohumeral joint opening has a negative effect on flexion and supination mobility.