Execution
- 1Position the patient prone or standing with the Achilles tendon visible and palpable.
- 2Identify a painful nodule or thickened area in the tendon.
- 3Palpate the tender area while the patient or examiner moves the ankle through dorsiflexion and plantarflexion.
- 4Observe whether the tender nodule moves with tendon excursion.
- 5Compare with areas of paratendon or superficial tenderness that may remain fixed.
Positive outcome
The test is positive for intratendinous Achilles pathology when the tender thickened area moves with ankle motion. A fixed tender area suggests paratendinopathy or superficial tissue involvement rather than intratendinous change. The finding should be paired with tendon palpation and load-related pain history.
Studies
| Study | Reliability | Sn | Sp | LR+ | LR− |
|---|---|---|---|---|---|
| Maffulli et al. (2003) | reproducibility and validity study | 42 | 88 | 3.5 | 0.66 |
| Hutchison et al. (2013) | systematic review | NA | NA | NA | NA |
CommentArc sign is conceptually useful for differentiating intratendinous from paratendinous tenderness, but sensitivity is low. Systematic reviews describe mixed validity for Achilles tendinopathy clinical tests. It is an adjunct to history and load-based assessment rather than a stand-alone diagnosis.
Moderate Clinical Value