Adhesive Capsulitis vs Rotator Cuff Tear: How to Diagnose Frozen Shoulder
Upper Limb · 7 min read · 2026-04-04
Introduction
A patient walks in with a stiff, painful shoulder. Is it a rotator cuff tear or adhesive capsulitis? The two conditions share enough overlap that they are routinely confused, but a single examination manoeuvre — passive range of motion — separates them definitively.
Adhesive Capsulitis (Frozen Shoulder)
A pathological fibrosis and contracture of the glenohumeral joint capsule, particularly the coracohumeral ligament and rotator interval. Idiopathic in many cases, but classically associated with diabetes, thyroid disease, and prolonged immobilisation.
Three phases:
- Freezing (painful) — 2 to 9 months. Progressive pain and gradual loss of motion.
- Frozen (stiff) — 4 to 12 months. Pain decreases but motion is severely restricted.
- Thawing — 6 to 24 months. Gradual return of motion.
Hallmark exam finding: loss of both active AND passive range of motion, particularly external rotation with the arm at the side. This loss of passive external rotation is the single most specific finding.
Rotator Cuff Tear
A partial or full-thickness tear of one or more cuff tendons. Pain limits active motion, but the joint capsule itself is normal.
Hallmark exam finding: active range of motion is restricted by pain or weakness, but passive range of motion is preserved (or close to it). When the examiner moves the arm, it goes through near-full range.
The Decisive Test
Sit the patient with their elbow tucked at the side and elbow flexed to 90°. Passively externally rotate the shoulder.
- Frozen shoulder: a hard endpoint at 10–30° with no further give. Both arms compared side-by-side reveal the asymmetry instantly.
- Cuff tear: external rotation reaches the normal 70–90° (though active rotation may be weak)
Quick Comparison
Common Pitfall
The most frequent error is testing only active range of motion. A patient with cuff tear and a patient with frozen shoulder both fail to lift their arm — but only the frozen shoulder patient fails when you lift it for them. Always perform passive ROM after active.
Clinical Pearl
Bilateral frozen shoulder, or frozen shoulder in a patient under 40, mandates a screen for diabetes and thyroid disease. The lifetime risk of adhesive capsulitis in diabetics is 10–20%, with bilateral involvement common.
Summary
Restricted passive external rotation = adhesive capsulitis. Preserved passive motion with weak active motion = cuff tear. One test, two diagnoses.