Classification
- Type: Synovial pivot (uniaxial)
- Degrees of freedom: 1 (pronation/supination — rotation of the radius around the ulna)
- Region: Elbow complex (shares a common capsule with the humeroulnar and humeroradial joints); mechanically linked to the anatomy/joints/distal-radioulnar joint
Articular Surfaces
- Radial head (convex rim): The circumferential articular surface of the radial head rotates within the osteoligamentous ring formed by the radial notch and annular ligament. The rim is covered with hyaline cartilage.
- Radial notch of the ulna (concave): A shallow concavity on the lateral aspect of the coronoid process. It accommodates approximately one-quarter of the radial head circumference. Covered with hyaline cartilage.
- Annular ligament: Completes the ring around the radial head, providing approximately three-quarters of the containment. Its inner surface is lined with fibrocartilage to articulate with the radial head.
Movements and ROM
Functional ROM: Most activities of daily living require approximately 50° of pronation and 50° of supination. Full pronation is needed for palm-down activities (typing, pushing); full supination for palm-up activities (carrying a bowl, turning a key).
Capsular Pattern
Equal limitation of pronation and supination (approximately equal)
Some sources list supination as slightly more limited than pronation. The restriction is symmetric or near-symmetric, distinguishing capsular from non-capsular patterns.
Resting Position
- 70° elbow flexion, 35° supination
- The annular ligament is most relaxed; maximum radial head mobility
Close-Packed Position
- 5° supination, full elbow extension
- Maximum tension on the annular ligament and interosseous membrane
End-Feels
| Movement |
Normal End-Feel |
Type |
| Pronation |
Capsular (firm) |
Interosseous membrane, posterior capsule, supinator muscle stretch. May include tissue approximation (radius crossing over ulna) in muscular individuals. |
| Supination |
Capsular (firm) |
Interosseous membrane, anterior capsule, pronator muscle stretch |
Ligaments
Annular Ligament
- Attachments: Anterior margin of the radial notch → posterior margin of the radial notch, forming a ring around the radial head
- Function: The primary stabilizer of the proximal radioulnar joint. Holds the radial head against the ulna while allowing free rotation. The ligament narrows slightly distally, which helps prevent the radial head from pulling out inferiorly.
- Injury mechanism: In children under 5 — axial traction on a pronated forearm (pulling a child by the hand) subluxes the radial head from the annular ligament (nursemaid's elbow). In adults — radial head fracture or dislocation may tear or stretch the annular ligament.
- Assessment test: Palpate the radial head while the patient pronates and supinates — pain, crepitus, or a mechanical block indicates pathology. In children: the child holds the arm in pronation and slight flexion, refuses to supinate.
Interosseous Membrane
- Attachments: Along the interosseous borders of the radius and ulna; fibers run obliquely from the radius (distally) to the ulna (proximally)
- Function: Transmits force from the radius to the ulna (and therefore to the humerus). The oblique fiber orientation means that compressive forces through the radius (e.g., falling on the hand) are transmitted proximally across the membrane to the ulna. Also provides attachment surface for forearm muscles and separates the anterior and posterior compartments.
- Clinical relevance: The interosseous membrane tightens at the extremes of pronation and supination, contributing to the capsular end-feel. Fibrosis of the membrane after forearm fracture restricts pronation/supination.
Mobilization Techniques
Hands-on instruction is required. The descriptions below provide clinical reference detail for understanding and supervised practice. They are not a substitute for instructor-led technique training. Correct hand placement, force dosage, and tissue response interpretation require hands-on coaching and feedback.
Convex-Concave Rule at the Proximal Radioulnar Joint
The convex radial head rotates within the concave osteoligamentous ring (radial notch + annular ligament). The primary mobilization is a
spin (rotation) of the radial head, not a translatory glide. For spin movements, the convex-concave rule does not apply in the same way. Anterior-posterior glides of the radial head are also used to facilitate pronation and supination.
General Contraindications
- Absolute: Radial head fracture or dislocation, annular ligament disruption, acute Monteggia fracture-dislocation, joint infection
- Relative: Recent radial head fracture (healed — follow surgeon timeline), radial head replacement, elbow instability
Dorsal (Posterior) Radial Head Glide
Purpose: Restores pronation. During pronation, the radial head glides posteriorly in the annular ligament. A restricted posterior glide limits pronation.
Patient position:
- Seated or supine
- Elbow at 70° flexion (resting position)
- Forearm in neutral position
Hand placement:
- Stabilizing hand: Grips the proximal ulna from the medial side, stabilizing it against the table or the clinician's body
- Mobilizing hand: Thumb contacts the anterior surface of the radial head. Index finger wraps posteriorly for support. Force directed posteriorly (dorsally).
Technique execution:
- Apply a slow, sustained or oscillatory force directed posteriorly on the radial head
- Grade I–II: Gentle oscillations for pain modulation and assessment of posterior glide
- Grade III: Oscillations into the posterior end-range resistance — stretching the anterior capsule and interosseous membrane
- Duration: 20–30 seconds per set, 2–3 sets
- Reassess pronation PROM between sets
Indications:
- Decreased pronation with a capsular (firm) end-feel
- Restricted posterior radial head glide on joint play testing
- Post-fracture or post-immobilization pronation limitation
Technique notes:
- Common error: Applying force to the radial shaft rather than the radial head — this produces forearm rotation, not a translatory glide.
- Palpation landmark: Locate the radial head in the "soft spot" triangle (lateral epicondyle, olecranon, radial head). Confirm by asking the patient to pronate/supinate while palpating.
- Reassessment: Re-test pronation PROM. Improvement confirms anterior capsular or radial head restriction.
Ventral (Anterior) Radial Head Glide
Purpose: Restores supination. During supination, the radial head glides anteriorly in the annular ligament. A restricted anterior glide limits supination.
Patient position:
- Seated or supine
- Elbow at 70° flexion
- Forearm in neutral
Hand placement:
- Stabilizing hand: Grips the proximal ulna, stabilizing it
- Mobilizing hand: Thumb contacts the posterior surface of the radial head. Force directed anteriorly (ventrally).
Technique execution:
- Apply a slow, sustained or oscillatory force directed anteriorly on the radial head
- Grade I–II: Gentle oscillations for pain modulation
- Grade III: Oscillations into the anterior end-range resistance — stretching the posterior capsule
- Duration: 20–30 seconds per set, 2–3 sets
Indications:
- Decreased supination with a capsular (firm) end-feel
- Restricted anterior radial head glide on joint play testing
- Post-fracture or post-immobilization supination limitation
Technique notes:
- Important: If pronation and supination are both restricted equally (capsular pattern), mobilize both directions and combine with humeroulnar/humeroradial techniques for comprehensive elbow mobilization.
- Reassessment: Re-test supination PROM.
Muscles Crossing This Joint
Pronators
- anatomy/muscles/pronator-teres — two heads straddle the median nerve; primary pronator at all elbow angles
- anatomy/muscles/pronator-quadratus — deep forearm muscle; primary pronator at the distal radioulnar joint but contributes to total pronation force
Supinators
- anatomy/muscles/biceps-brachii — most powerful supinator when the elbow is flexed to 90° (the radial tuberosity is maximally displaced medially in pronation, giving the biceps maximum mechanical advantage to supinate)
- anatomy/muscles/supinator — wraps around the proximal radius; the primary supinator when the elbow is extended (biceps is mechanically disadvantaged in extension)
Conditions Affecting This Joint
- Nursemaid's elbow (pulled elbow) — radial head subluxation in children under 5; annular ligament interposition
- Radial head fracture — Mason classification; axial loading through the radius compresses the radial head against the capitulum
- Monteggia fracture-dislocation — ulnar shaft fracture with proximal radioulnar dislocation; the annular ligament is disrupted
- Post-fracture pronation/supination loss — fibrosis of the annular ligament, interosseous membrane, or capsule after forearm fracture or prolonged immobilization
Clinical Notes
- Pronation/supination loss is functionally disabling. Loss of these movements prevents hand positioning for most activities of daily living — turning doorknobs, using utensils, typing, personal hygiene. Early mobilization after forearm fracture is essential to prevent permanent loss.
- The proximal and distal radioulnar joints are mechanically linked. Restriction at one joint affects the other. If pronation/supination is limited, assess both joints — the restriction may be primarily at the proximal radioulnar, the distal radioulnar, or the interosseous membrane.
- Biceps is the most powerful supinator at 90° flexion. This is why clinical supination strength testing is performed with the elbow at 90° — it positions the biceps for maximum mechanical advantage and allows comparison of biceps-assisted vs supinator-only strength.
Key Takeaways
- The proximal and distal radioulnar joints are mechanically obligated — restriction at one affects the other; always assess both when pronation/supination is limited.
- Posterior radial head glide restores pronation; anterior radial head glide restores supination — the radial head translates within the annular ligament ring.
- The annular ligament is the primary stabilizer — its laxity in young children allows nursemaid's elbow from axial traction on a pronated forearm.
