Sulcus Sign Test: How to Assess Inferior Shoulder Instability

The Sulcus Sign Test is one of the few shoulder tests that specifically targets inferior instability — the tendency of the humeral head to shift downward within the glenoid cavity. It's especially relevant for people with generalized hypermobility or athletes with a history of shoulder dislocations or subluxations.

What does this test measure?

The Sulcus Sign Test assesses the laxity of the inferior joint capsule and inferior glenohumeral ligament, by observing how far the humeral head shifts downward relative to the glenoid when downward traction is applied to the relaxed arm.

Equipment needed

• None

Step-by-step protocol

1. The person stands or sits with the arm relaxed at their side, in a neutral position
2. Hold the person's forearm or elbow and apply gentle downward (caudal) traction, as if pulling the arm toward the floor
3. Watch the area just below the acromion: if a visible "gap" or "sulcus" appears between the acromion and the humeral head, estimate its depth
4. Repeat on the other arm to compare (hypermobility is often bilateral, but it's worth confirming)
5. If you're unsure, repeat the test with the arm in slight external rotation — this should tighten the capsule and reduce the sulcus if the laxity is simply "normal" for that person

Common mistakes

• Applying traction with the arm in any position other than neutral/relaxed, which alters capsular tension
• Skipping the comparison with the contralateral side (some people have constitutional generalized laxity, not pathological)
• Confusing generalized hypermobility (asymptomatic) with symptomatic instability (with subluxation/dislocation episodes)

How to interpret the results

Grade	Sulcus depth	Interpretation
Grade 0-1	No visible sulcus or minimal (< 1 cm)	Negative / laxity within normal range
Grade 2	Moderate sulcus (approx. 1-2 cm)	Increased laxity, monitor for associated symptoms
Grade 3	Marked sulcus (> 2 cm)	Positive — suggests significant inferior capsular laxity, possible multidirectional instability if accompanied by symptoms

It's important to stress that a positive sulcus sign alone doesn't mean "pathological instability." Many people have constitutional laxity with no functional issues whatsoever. The test becomes clinically relevant when combined with actual symptoms (a feeling the shoulder "pops out," previous subluxation/dislocation episodes, pain during activity).

Related tests

The Sulcus Sign Test is usually part of an instability test battery alongside:

• Apprehension Test — specifically assesses anterior instability
• Relocation Test — complements the apprehension test by confirming the anterior component

If all three (sulcus, apprehension, and relocation) are positive together with symptoms, the suspicion of multidirectional instability increases significantly.

Why tracking this matters

In people with hypermobility, training tends to shift toward motor control work and active shoulder stability rather than additional mobility (which they usually have plenty of already). Detecting and recording this pattern helps you justify that approach and monitor whether control improves over time, even though the underlying structural laxity itself won't change. In Movalytics you can log the sulcus sign grade alongside the presence or absence of associated symptoms, giving you the full picture at every assessment.

Frequently asked questions

Does a positive sulcus sign mean my shoulder is "bad"? Not on its own. It indicates laxity, which can be completely normal for your anatomy. It only becomes relevant if it's accompanied by functional symptoms (a feeling of instability, pain, subluxation episodes). Can hypermobility be "corrected" with training? Ligament laxity itself doesn't change much, but neuromuscular control and active stability can absolutely be trained, and that's what makes the functional difference. Is this test painful? It shouldn't be. It's a gentle traction maneuver; if it causes significant pain, there may be other factors at play that should be assessed separately.