Asymmetry of the ULNT1 elbow extension range-of-motion in a healthy population: Consequences for clinical practice and research

ObjectivesTo investigate the effect of isolated muscular variance, side and hand dominance on elbow-extension range-of-motion (EE-ROM) of the median nerve upper limb neurodynamic test (ULNT1). This study analyzes these variables potential to influence ULNT1 EE-ROM symmetry and the possible consequences for clinical practice and research.Study designControlled laboratory study, cross-sectional.BackgroundNo normative data exist to interpret correctly EE-ROM. Clinical interpretation is based on bilateral comparison. This procedure assumes natural EE-ROM symmetry, with lack of scientific evidence.MethodsNineteen participants with Langer’s axillary arch (LAA), a muscular variant bridging the brachial plexus, were selected from 640 healthy volunteers, together with a matched control group. ULNT1 EE-ROM’s were measured using the Vicon® optoelectronic system.ResultsA full mixed model revealed no significant effects on EE-ROM for LAA and the variable side. Significant differences were found in EE-ROM between dominant and non-dominant sides (standard ULNT1 test position: 2.84° ± 1.60°, p = 0.0004; ULNT1 with differentiating maneuver: 3.05° ± 1.98°, p = 0.003). Approximately 30% of the subjects showed clinically detectable restriction (≥10°) of the dominant side EE-ROM.ConclusionHand dominance is significantly associated with restriction of EE-ROM, which results in a clinically detectable asymmetry. This compromises the clinical procedure of comparing the patient’s EE-ROM to the opposite side. Erroneous conclusions could result in side to side analyses, if the effect is not taken into account in neurodynamic research.