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Dorsal deltoid ligament

The dorsal deltoid ligament is the dorsal capsuloligamentous complex of the thumb CMC (trapeziometacarpal) joint, formed primarily by the dorsal radial ligament (DRL), dorsal central ligament (DCL), and posterior oblique ligament (POL). These fibers span from the dorsal trapezium to the dorsal base of the first metacarpal, resisting dorsoradial translation and dorsal subluxation during pinch and grip. The palmar counterpart is the anterior oblique (AOL, “beak”) ligament (and volar/ulnar oblique fibers), which stabilizes the volar beak of the first metacarpal against the trapezium. Thus, the AOL is volar (anterior) to the dorsal deltoid, not posterior.

Synonyms

  • Dorsal capsuloligamentous complex (thumb CMC)

  • Dorsal radial–central–posterior oblique ligament complex

  • Dorsal deltoid complex of the trapeziometacarpal joint

Location and Structure

  • Joint: Thumb CMC (trapeziometacarpal) joint (trapezium ↔ base of first metacarpal)

  • Dorsal deltoid components: DRL, DCL, POL fanning obliquely across the dorsal capsule to the dorsal radial/ulnar metacarpal base

  • Palmar counterpart (for context): AOL/beak (and volar/ulnar oblique fibers) from volar trapezium to the volar beak of the first metacarpal

  • Configuration: Dorsal “deltoid” fan balanced by a palmar/volar buttress (AOL) for multiplanar stability

Attachments

  • Proximal: Dorsal trapezium (ridge and dorsal capsule)

  • Distal: Dorsal radial and dorsoulnar aspects of the base of the first metacarpal

  • Palmar counterpart: AOL from volar trapezium to volar beak of first metacarpal

Relations

  • Superficial: EPB/EPL tendons and dorsal capsule

  • Deep: Dorsal articular surface of trapezium and metacarpal base

  • Radial/Ulnar: Collateral capsular thickenings blending with DRL/POL

  • Palmar: AOL (beak ligament) and volar capsule/thenar musculature

Function

  • Primary dorsal restraint: Prevents dorsoradial translation and dorsal subluxation of the first metacarpal

  • Rotational control: Limits excessive pronation/supination at the CMC during key pinch

  • Synergy with AOL: Dorsal deltoid + AOL provide coupled dorsal–volar stability in opposition and pinch

Clinical Significance

  • CMC instability/early osteoarthritis: Attenuation of DRL/POL with AOL degeneration leads to dorsoradial subluxation and Eaton–Littler OA progression

  • Sprain/partial tear: Pain with key pinch, grind test positivity; may precede radiographic OA

  • Complete capsuloligamentous failure: Dorsal subluxation, osteophytes, and adduction contracture of the first metacarpal

  • Surgical relevance: Ligament reconstruction (e.g., LRTI, dorsal capsulodesis) targets dorsal deltoid and AOL balance

MRI Appearance

  • T1-weighted:

    • Ligaments (DRL/DCL/POL): Low signal (dark) linear bands along dorsal CMC capsule

    • AOL (palmar): Low-signal band volar to the joint (helps orientation)

    • Sprain/degeneration: Thickening or indistinct intermediate signal; small dorsal capsular ganglia may be seen

  • T2-weighted:

    • Normal dorsal deltoid: Low signal, sharply marginated

    • Partial tear: Focal hyperintense signal within fibers or at bony attachment; adjacent dorsal capsular edema

    • Complete tear/insufficiency: Discontinuity with periarticular fluid; may see dorsoradial subluxation of metacarpal base

  • STIR:

    • Normal: Intermediate-to-dark ligament signal

    • Pathology: Bright periligamentous edema, synovitis in the dorsal recess, marrow edema at trapezium or metacarpal base

  • PD Fat-Sat:

    • Normal: Dark, taut fibers of DRL/DCL/POL

    • Injury: Hyperintense intraligamentous signal or enthesopathy; delineates AOL volarly for comparison

  • T1 Fat-Sat Post-Contrast:

    • Synovitis/capsulitis: Linear or diffuse enhancement along dorsal capsule

    • Chronic scarring: Mild peripheral enhancement with central low-signal fibrosis

CT Appearance

  • Non-contrast CT:

    • Ligaments not directly seen (thin soft tissue), but shows dorsoradial subluxation, osteophytes, subchondral sclerosis/cysts at trapezium and metacarpal base

    • Avulsion fragments at dorsal metacarpal base or trapezium in acute injury

  • Post-contrast CT:

    • Highlights pericapsular thickening/enhancement in inflammation; defines osteophytes and joint space narrowing

CT Arthrography Appearance

  • Normal: Contrast confined to CMC joint recesses; dorsal capsule appears intact with no extra-articular leak

  • Partial tear: Contrast tracks along dorsal capsule/ligament margins without full-thickness breach

  • Complete tear/capsular rent: Extravasation dorsally toward EPL/EPB planes; delineates defect edges

  • Correlation with AOL: Volar contrast pooling can indicate AOL attenuation/tear when combined with dorsal deltoid injury, explaining bidirectional instability

MRI images

Dorsal deltoid ligament axial cross sectional anatomy 3T MRI AI enhanced radiology image-img-00000-00000

MRI images

Dorsal deltoid ligament axial cross sectional anatomy 3T MRI AI enhanced radiology image-img-00000-00000_00001

MRI images

Dorsal deltoid ligament of thumb coronal