What does Morton's sign help to identify?

Morton's sign is a diagnostic tool used primarily to identify a neuroma, particularly Morton's neuroma, which occurs commonly between the third and fourth metatarsals of the foot. When applying pressure to the metatarsal heads, typically in a dorsal direction, a patient may experience pain, tingling, or a feeling of a lump, which indicates the presence of this neuroma.

In the context of the other options, ligament sprains generally present with swelling, bruising, and joint instability, which Morton's sign does not specifically evaluate. Similarly, while bone fractures can cause pain, they do not elicit the same symptoms associated with Morton's neuroma; fractures typically have a different presentation seen on imaging. Tendonitis involves inflammation of a tendon and presents with localized pain during movement or palpation rather than the specific nerve-related symptoms indicative of a neuroma. Cartilage injuries can cause joint pain and swelling but, like fractures and tendonitis, do not align with the characteristics assessed by Morton's sign.

Thus, the primary purpose of Morton's sign is to draw attention to the likelihood of a neuroma, making the identification of this condition the correct interpretation of the sign.