Execution:
- Patient is in standing or sitting position
- Support the patient’s hand so that it is completely relaxed with fingers partially flexed
- Grasp the patient’s middle finger proximal to the distal interphalangeal joint
- Flick the patient’s nail with your thumb
Positive Outcome: Quick adduction of patient’s thumb and flexion of finger
| Study | Reliability | Sn | Sp | LR+ | LR- |
| Grijalva et al. (2015) | NA | 59 | 49 | 1.16 | 0.84 |
| Cook et al. (2009) | ĸ=0.76 | 44 | 75 | 1.8 | 0.7 |
| Annaswamy et al. (2012) | intra-rater κ = 0.89, inter-rater κ=0.65 | NA | NA | NA | NA |
| Comment: Low predictive value to be relied upon alone | |||||
