Dr. Kevin Yip

Dr Kevin Yip
Orthopaedic Surgeon
MBBS(UK), FRCS(EDIN), FAM(SING), FHKCOS(ORTHO)

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Wrist Anatomy and Examination

Basics

Description
  • Bones: The wrist is composed of 8 carpal bones in 2 rows (proximal and distal); from radial to ulnar:
    • Proximal row:
      • Scaphoid (or navicular)
      • Lunate
      • Triquetrum
      • Pisiform
    • Distal row:
      • Trapezium
      • Trapezoid
      • Capitate
      • Hamate
  • Tunnels: The wrist has 6 dorsal and 2 volar (or palmar) compartments (or tunnels) that transport tendons to the hand.
    • Compartment I:
      • The 1st (most radial) tunnel transports the abductor pollicis longus and the extensor pollicis brevis tendons.
      • These tendons represent the radial border of the anatomic snuffbox
      • This compartment is a site for stenosing tenosynovitis (de Quervain tenosynovitis), characterized by inflammation of the synovial lining of the tunnel that narrows the opening and results in pain when the tendons move.
    • Compartment II:
      • On the radial side of the radial tubercle, it houses the extensor carpi radialis longus and brevis.
    • Compartment III:
      • On the ulnar side of the radial tubercle, it contains the extensor pollicis longus.
      • This compartment defines the ulnar border of the snuffbox.
      • Palpates along the length of this tendon to feel for signs of rupture.
      • It is not uncommon to find this tendon ruptured in association with rheumatoid arthritis.
    • Compartment IV:
      • Lies just ulnar to compartment III and just radial to the radioulnar articulation
      • Contains the extensor digitorum communis and the independent extensor indicis
    • Compartment V:
      • Overlies the distal ends of the radioulnar joint on the dorsum of the wrist
      • Contains the extensor digiti minimi tendon
    • Compartment VI:
      • Contains the extensor carpi ulnaris tendon and lies between the apex of the ulnar styloid process and the ulnar head
      • In rheumatoid arthritis, this tendon may become displaced in an ulnar direction or may rupture.
Diagnosis
Signs and Symptoms
  • Symptoms can be referred to the wrist from the elbow, shoulder, and the cervical spine, and causes include the following:
    • Herniated cervical discs
    • Osteoarthritis
    • Brachial plexus outlet syndromes
    • Elbow and shoulder entrapment syndromes
History
  • Demographics: Age, handedness, occupation, avocational activities
  • Previous wrist injury or surgery
  • Chief complaint
  • Symptoms: Onset, relation to activities, exacerbating/improving factors, frequency, duration, night/day
  • Work status
  • Workers’ compensation status
Physical Exam
  • Inspection:
    • Bilateral comparison is a useful, quick way to identify the presence of pathologic signs.
    • Because symptoms can be referred from other areas of the body, wrist examination requires exposure of the entire upper extremity, including the cervical spine.
    • The examiner may observe the patient’s wrist movements as he or she undresses and determine whether motion is smooth and natural or stiff and jerky.
  • Palpation of skin:
    • Evaluate for any unusually warm or dry areas.
    • Extensive localized warmth may indicate infection, whereas notable dryness (anhidrosis) may suggest nerve damage.
    • Give attention to any lesions, swellings, or scars observed during inspection.
  • Palpation of bones:
    • Radial styloid process:
      • Lies lateral when the palm faces anteriorly
      • Its most prominent point lies just proximal to the wrist joint.
    • Anatomic snuffbox:
      • This small depression is located immediately distal and slightly dorsal to the radial styloid process.
      • Palpable and easy to visualize when the patient extends the thumb laterally away from the fingers
    • Scaphoid:
      • Lies on the radial aspect of the wrist and forms the floor of the snuffbox
      • The most commonly fractured of all the carpal bones
      • Tenderness to palpation over the snuffbox suggests a fracture of the scaphoid.
    • Trapezium:
      • Located on the radial side of the wrist and articulates with the 1st metacarpal.
      • The palpable saddle-like trapezium 1st metacarpal joint is most commonly involved in degenerative joint disease.
      • Grind test:
        • This test evaluates for 1st CMC joint degenerative joint disease.
        • The examiner stabilizes the CMC joint with 1 hand and, with the other, axially loads the patient’s hand.
        • The examiner’s 1st hand then moves the metacarpal base laterally in several directions, to exacerbate symptoms.
        • Reproduction of the patient’s symptoms (a positive result) supports the presence of 1st CMC arthritis.
    • Capitate:
      • Largest of all the carpal bones
      • Palpable immediately proximal to the base of the 3rd metacarpal (the largest and most prominent of the metacarpal bases).
    • Lunate:
      • Lies just proximal to the capitate, in the proximal carpal row, and articulates proximally with the radius and distally with the capitate.
      • The most frequently dislocated and the 2nd most often fractured wrist bone.
      • The lunate, capitate, and base of the 3rd metacarpal are in line with each other and are covered by the ECRB tendon, which inserts into the base of the 3rd metacarpal.
    • Ulnar styloid process:
      • Can be palpated at the distal aspect of the ulna medially and posteriorly
      • A groove on its distal tip houses the extensor carpi ulnaris tendon.
    • Triquetrum:
      • Lies just distal to the ulnar styloid process
    • Pisiform:
      • This small sesamoid bone lies anterolateral to the triquetrum and sits within the flexor carpi ulnaris tendon.
    • Hook of the hamate:
      • Located slightly dorsal and radial to the pisiform
      • Forms the lateral (radial) border of the tunnel of Guyon, which encompasses the ulnar nerve and artery; the medial border of the tunnel of Guyon is the pisiform.
    • Finkelstein test:
      • This test evaluates specifically for stenosing tenosynovitis in compartment I tendons.
      • The patient is instructed to make a fist with the thumb tucked inside the other fingers.
      • Then the examiner stabilizes the patient’s forearm with 1 hand and deviates the patient’s wrist in an ulnar direction with the other hand.
      • Sharp pain felt in the tunnel region strongly supports a diagnosis of stenosing tenosynovitis.

    P.483
  • Palpation of the palmar aspect of the wrist:
    • Palmaris longus:
      • Bisects the anterior aspect of the wrist; its distal end also is the anterior surface of the carpal tunnel.
      • To palpate the palmaris longus, have the patient flex the wrist and touch the tips of the thumb and small finger together in apposition; the palmaris longus becomes prominent along the midline of the anterior aspect of the wrist.
    • Carpal tunnel:
      • Lies deep to the palmaris longus and is defined proximally by the pisiform and the tubercle of the scaphoid and distally by the hook of the hamate and the tubercle of the trapezium
      • The transverse carpal ligament, part of the volar carpal ligament, runs between those bony prominences and forms a fibrous sheath containing the carpal tunnel anteriorly within a fibro-osseous tunnel.
      • Posteriorly, the carpal tunnel is bordered by the carpal bones.
      • The compartment transports the median nerve and the finger flexor tendons from the forearm to the hand.
      • Clinical significance:
        • Compression of the median nerve (CTS) can restrict motor function and sensation along the median nerve distribution of the hand.
        • Patients note discomfort over the wrist and numbness of the thumb and the index and middle fingers.
        • Patients often have paresthesias at night.
      • To support a diagnosis of CTS, reproduce:
        • Pain in the median nerve distribution by tapping over the volar carpal ligament (Tinel sign)
        • Symptoms by flexing the patient’s wrist to its maximal degrees and holding for at least 1 minute (Phalen test)
    • Flexor carpi radialis:
      • Flexor carpi radialis tendinitis can cause pain over the flexor aspect of the wrist.
      • On examination, pain is noted with palpation over the flexor carpi radialis tunnel (from 3 cm proximal to the wrist to the main insertion of the flexor carpi radialis on the base of the second metacarpal).
      • Examination also usually produces increased pain with resisted wrist flexion and resisted radial deviation of the wrist.
    • Vascular anatomy:
      • The radial artery can be palpated just radial to the flexor carpi radialis tendon.
      • The pulse of the ulnar artery may be palpated proximal to the pisiform bone just before it crosses the wrist on the anterior aspect of the ulna.
      • Most patients have both arteries, with the ulnar artery usually providing the dominant blood supply.
  • ROM (use bilateral comparison to evaluate the patient’s restrictions):
    • Flexion (normal, 70-80°)
    • Extension (normal, 70-80°)
    • Radial deviation (normal, up to ~20°)
    • Ulnar deviation (normal, up to ~30°)
    • Supination (normal, 90°)
    • Pronation (normal, 90°)
  • Neurologic examination (the focus is on muscular assessment and sensation testing).
  • Motor testing:
    • Wrist extension (C6)
    • Flexion (C7)
    • Supination (C5, C6)
    • Pronation (C6, C8, T1)
  • Sensation testing (test volar and dorsal aspects of the wrist and compared results with those of the contralateral wrist)
  • Peripheral nerve innervation (test sensation in the median, ulnar, and radial nerve distributions in the hand)
Tests
Imaging
  • Radiographs should include at least 3 views of the wrist (posteroanterior, lateral, and oblique).
    • A scaphoid view (wrist in ulnar deviation) can be helpful in assessing for a scaphoid fracture.
    • A clenched fist view can suggest a possible scapholunate ligament tear.
  • Scaphoid fractures may not be evident on initial radiographs and may be seen on repeat radiographs 7-10 days later.
Treatment
General Measures
Pregnancy Considerations
  • If the pregnant patient has symptoms of numbness and tingling in her fingers, the clinician should have a high index of suspicion for CTS (median neuropathy at the wrist).
  • An increased incidence of de Quervain tenosynovitis also occurs in new mothers. (The clinician should check for this condition by using the Finkelstein test.)
Miscellaneous
FAQ
Q: How can you differentiate between de Quervain tenosynovitis and thumb CMC arthritis on examination?
A: In de Quervain tenosynovitis, the patient is tender to palpation over the 1st dorsal compartment tendons over the radial styloid versus tenderness over the CMC joint in CMC arthritis. In de Quervain tenosynovitis, the patient has pain with ulnar deviation of the wrist with the thumb tucked into a fist, whereas with CMC arthritis, the patient has a positive grind test.
Q: What is the anatomic landmark for the scaphoid?
A: The “anatomic snuffbox is a small depression just distal and dorsal to the radial styloid process. It is easy to visualize when the patient extends the thumb laterally away from the fingers. Tenderness to palpation in this area after trauma suggests possible scaphoid fracture.

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