Bepaling van beenlengteverschil met de plankjesmethode: Nauwkeurige uitkomsten, onafhankelijk van ervaring van de onderzoeker

Objective. To determine the precision and reliability of the indirect limb-length measurement, and the inter-observer variance between doctors differing in level of experience. Design. Descriptive. Method. Indirect limb-length measurement by placing 0.5 cm-thick wooden boards under the foot of the shorter leg until the difference in length was corrected, was performed by 3 observers differing in experience (medical student, resident and orthopaedic surgeon) on 66 patients with unilateral femoral-shaft fractures treated with a femoral nail. The group of patients consisted of 51 men and 15 women with a median age of 30 years (range: 18-90). In total 17 observers participated and 177 limblength measurements were performed. The measurements obtained were compared with limb-length measurements obtained by orthoradiograms of the entire leg. Results. Of the 177 indirect limb-length measurements, 144 (81%) differed by 0-1.0 cm compared with the limb length obtained by orthoradiogram. There was no statistically significant difference in the limb-length measurements obtained by the three groups of observers with different experience levels. There was a certain degree of correlation between values measured by medical students and residents (r = 0.7). When comparing the measurements carried out by staff members with those of residents and medical students, respectively, a lower degree of correlation was found (r = 0.6 and 0.5, respectively). Conclusion. Indirect limb-length measurement with wooden boards was accurate. Experience did not play an essential role.