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Radiocarpal joint (wrist joint)

The radiocarpal joint, commonly known as the wrist joint, is a synovial ellipsoid (condyloid) joint between the distal end of the radius and the proximal row of carpal bones (scaphoid, lunate, and triquetrum via articular disc). It plays a key role in wrist mobility, allowing flexion, extension, abduction (radial deviation), and adduction (ulnar deviation).

It is one of the most functionally complex joints in the upper limb, transmitting forces from the hand to the forearm while maintaining stability and precision of motion. The joint is reinforced by a strong fibrous capsule and several specialized ligaments that coordinate movement with the midcarpal and intercarpal joints.

Synonyms

  • Wrist joint

  • Radiocarpal articulation

  • Distal radiocarpal articulation

Location and Structure

  • Type: Synovial ellipsoid joint

  • Articulating surfaces:

    • Proximal: Concave distal end of the radius and the articular disc of the distal radioulnar joint

    • Distal: Convex surfaces of the scaphoid, lunate, and triquetrum (when wrist is in ulnar deviation)

  • Joint capsule: Encloses the articulation; thin dorsally, thick and reinforced ventrally

  • Synovial membrane: Lines the capsule and reflects onto articular margins

  • Joint cavity: Communicates with the midcarpal joint in some individuals

Relations

  • Anteriorly (palmar): Flexor carpi radialis, flexor pollicis longus, flexor digitorum profundus, and radiocarpal ligaments

  • Posteriorly (dorsal): Extensor tendons (extensor digitorum, extensor indicis, extensor carpi radialis longus and brevis)

  • Laterally: Radial collateral ligament, abductor pollicis longus, and extensor pollicis brevis tendons

  • Medially: Ulnar collateral ligament and tendon of flexor carpi ulnaris

Ligamentous Attachments

  • Palmar radiocarpal ligament: From anterior radius to scaphoid, lunate, and capitate; resists hyperextension

  • Dorsal radiocarpal ligament: From posterior radius to dorsal carpal bones; limits flexion

  • Radial collateral ligament: From radial styloid process to scaphoid; limits ulnar deviation

  • Ulnar collateral ligament: From ulnar styloid process to triquetrum and pisiform; limits radial deviation

  • Articular disc (triangular fibrocartilage): Separates the ulna from the carpal bones, forming part of the joint floor medially

Nerve Supply

  • Branches: Derived from the anterior and posterior interosseous nerves (from the median nerve) and the dorsal and deep branches of the ulnar nerve

Function

  • Flexion and extension: Approximately 80° flexion and 70° extension

  • Abduction (radial deviation): Around 15–20°

  • Adduction (ulnar deviation): Around 30–40°

  • Circumduction: Combination of all movements creating a conical motion

  • Load transmission: Transfers forces from hand to forearm during grip and impact

  • Fine motion control: Provides stability during complex wrist-hand coordination

Clinical Significance

  • Fractures: Commonly associated with distal radius fractures (Colles’, Smith’s) and scaphoid injuries

  • Ligament injuries: Radiocarpal or intercarpal ligament tears may cause instability and chronic pain

  • Arthritis: Osteoarthritis, rheumatoid arthritis, and post-traumatic arthritis affect articular cartilage and ligaments

  • TFCC injuries: Damage to the triangular fibrocartilage complex causes ulnar-sided wrist pain

  • Ganglion cysts: Frequently arise from radiocarpal joint capsule or ligaments

  • Imaging role: MRI is gold standard for soft-tissue and cartilage evaluation; CT for bone alignment and fractures

MRI Appearance

  • T1-weighted images:

    • Bone cortex: Low signal (dark)

    • Bone marrow: Bright (fatty marrow signal)

    • Articular cartilage: Smooth, thin, intermediate-to-low signal on bone surfaces

    • Ligaments and capsule: Low signal linear structures

    • Effusion: Appears as low-to-intermediate signal fluid in joint recesses

    • Pathology: Fractures show dark cortical disruption; synovial thickening appears intermediate

  • T2-weighted images:

    • Bone cortex: Low signal

    • Marrow: Bright, slightly less than on T1

    • Cartilage: Intermediate  signal 

    • Ligaments: Low signal, surrounded by bright joint fluid

    • Effusion and synovitis: Bright hyperintense

    • TFCC tears: Linear high-signal clefts through normally dark fibrocartilage

  • STIR:

    • Normal marrow: Intermediate-to-dark

    • Pathologic marrow: Bright in bone contusion, infection, or inflammatory arthropathy

    • Sensitive for early detection of synovitis, capsulitis, or bone edema

  • Proton Density Fat-Saturated (PD FS):

    • Normal cartilage and marrow: Intermediate-to-dark

    • Abnormal: Bright signal in regions of edema, ligament sprain, or capsular inflammation

    • Excellent for visualizing small effusions, cartilage defects, and ligament tears

  • T1 Fat-Sat Post-Contrast:

    • Normal synovium: Mild enhancement

    • Inflammatory arthritis: Diffuse synovial enhancement

    • Post-traumatic changes: Localized enhancement along capsule or ligaments

    • Ganglion cyst: Peripheral rim enhancement with non-enhancing center

CT Appearance

Non-Contrast CT:

  • Cortical bone: High attenuation, sharply defined

  • Trabecular bone: Fine internal pattern

  • Articular surfaces: Smooth and congruent; cartilage as thin low-density line

  • Pathology: Detects fractures, osteophytes, sclerosis, and malalignment

  • TFCC calcification or bone cysts may also be identified

CT VRT 3D image

Radiocarpal joint CT 3D VRT image -img-00000-00000

MRI image

Radiocarpal joint coronal cross sectional anatomy 3T MRI AI enhanced radiology image-img-00000-00000

CT image

Radiocarpal joint ct coronal image