Ortho - Wrist

• These notes cover the anatomy, biomechanics, pathologies, orthopedic tests, and home care for the wrist and hand

Carpal Tunnel Landmarks

• The carpal tunnel landmarks include the scaphoid tubercle, trapezium tubercle, hook of hamate, and pisiform.
• The flexor retinaculum attaches to these four points.

Anatomical Snuffbox Landmarks

• The lateral tendons are the abductor pollicis longus and extensor pollicis brevis.
• The medial tendon is the extensor pollicis longus.
• The scaphoid forms the floor.
• The radial artery exists inside the snuffbox space

Tunnel of Guyon

• Is formed between the pisiform and hook of hamate, covered by the pisohamate ligament
• Contains the ulnar nerve.

Joints and Ligaments of the Wrist

• The distal radioulnar joint is a synovial, pivot joint with articulation between the ulnar notch of the radius and the head of the ulna.
• The radiocarpal joint is a synovial, ellipsoidal joint with articulation between the distal end of the radius and the proximal surfaces of the scaphoid and lunate.
• The ulnomeniscotriquetral joint is a synovial ellipsoidal joint is between the meniscus (triangular piece of fibrocartilage distal to ulnar head) and the proximal surface of the triquetrum.
• Capsular strength/coaptation is weak in all three joints: distal radioulnar, radiocarpal, and ulnomeniscotriquetral.
• Key ligaments include the flexor and extensor retinacula and radial and ulnar collateral ligaments
• The flexor and extensor retinacula have six tunnels.
• The radial collateral ligament limits excessive abduction and ulnar deviation.
• The ulnar collateral ligament limits excessive adduction and radial deviation.

Functional Anatomy

• The distal radioulnar joint allows 1 degree of freedom (supination-pronation).
• The radiocarpal and ulnocarpal (UMT) joints allow 2 degrees of freedom (flexion-extension, radial deviation-ulnar deviation).
• Head of the ulna is convex, ulnar notch of the radius is concave.
• Carpals are convex adn the Radius and meniscus are concave
• Resting and closed packed positions require 10 degrees supination and 5 degrees supination resepectively.
• Limitation is equal in all directions for capuslar pattern of restriction
• ROM and end feel with supination at 0-90° firm, pronation at 0-70/90° firm/hard

Triangular Fibrocartilage Complex (TFCC)

• The triangular fibrocartilage complex includes the disc of the UMT.
• The TFCC is an important structure for wrist stability, has poor vascularization with slow healing.
• It's most aggravated by extension with pronation under load.

Wrist Biomechanics

• The wrist complex involves the distal radioulnar, radiocarpal, and midcarpal joints.
• Radiocarpal joint: articulation between the TFCC and carpals (lunate, triquetrum), extends the ulna, UMT joint included when discussing biomechanics
• Axis of flexion-extension: capitate
• Flexion primarily occurs at the midcarpal joint.
• Extension primarily occurs at the radiocarpal joint.
• Radiocarpal closed pack (full extension) results from asymmetry of scaphoid movement and relies on movement of the lunate on the scaphoid
• Convex-on-concave: movement is opposite in radial-ulnar deviation
• Full ulnar or radial deviation requires mobility between carpal rows.
• In ulnar deviation, both rows of carpals glide radially

Hand Biomechanics

• There's 1 longitudinal arch per digit.
• Digit 3 and the capitate are the most important
• There are 2 transverse arches.
• The transverse carpal arch runs through the distal row of carpals and is also known as the proximal transverse arch
• the distal transverse arch runs through the head of the metacarpals.
• Heads of the metacarpals consist of the distal transverse arch.
• Focal point locations: MC 3, capitate and lunate.
• With Cascade Sign and finger flexion, only the index finger flexes in the sagittal plane, but all other fingers flex in an oblique plane towards the scaphoid

Length-Tension Relationships

• Extrinsic muscles of the hand: wrist provides a stable base, wrist position controls the length of extrinsic hand muscle. Movements of the wrist are usually in reverse of the movements of the fingers and reinforce the action of extrinsic muscle of the fingers

Extrinsic Muscle Actions

• Wrist extensors stabilize the wrist and prevent long finger flexors from simultaneously flexing the wrist during finger flexion
• Wrist flexors activate to stabilize the wrist so long finger extensors can function effectively during finger extension
• As grip strength increases, extensors slacken allowing flexors to achieve a strong contraction.
• Greatest interphalangeal flexion force occurs with ulnar deviation and neutral flexion-extension.
• The weakest interphalangeal flexion force occurs when the wrist is in full flexion due to its lack of ability to generate forve

Dorsal Digital Expansion (DDE)

• DDE originates on the posterior, medial, and lateral surfaces of proximal phalanges 1-5.
• Extrinsic tendons are ED and EPL with intrinsic tendons are lumbricals and interossei,
• There's trifurcation on the dorsal aspect.

Prehension (grip) and Nerve Involvement

• Power grips contact the palm and are isometric.
• Precision grips do not contact the palm and are isotonic.
• Grabbing usually involves the median and ulnar nerves.
• Release involves the radial nerve.

Swan Neck Deformity

• MCP: Flexion
• PIP: Extension
• DIP: Flexion
• Causes: Muscle contracture or tearing of the volar plate at the PIP. Commonly seen with RA or post-trauma

Boutonniere Deformity

• MCP: Extension
• PIP: Flexion
• DIP: Extension
• Causes: Rupture of the central slip at the PIP of DDE. Commonly seen with RA or post-trauma

Dupuytren's Contracture

• Contracture of palmar fascia, which includes skin.
• The middle and ring fingers (digits 4, 5) are affected.
• There is development of fixed flexion deformity at MCP and PIP joints

Heberden's and Bouchard's Nodes

• Heberden's Nodes: arthritic changes on dorsal surfaces of DIPs.
• Bouchard's Nodes: arthritic changes on dorsal surfaces of PIPs

Drifts & Mallet Finger

• Ulnar Drift: with RA, changes in MCP result in pull on long tendons.
• Radial Drift: with OA
• Mallet Finger is when distal phalanx is flexed due to avulsion or rupture of the extensor tendon at the site of insertion

Thumb Deformities

• Zigzag deformity and Z deformity can affect the thumb.
• The CMC is flexed, MCP hyperextended, and IP partially flexed in a Zigzag deformity. Associated with RA.
• The MCP is flexed, and the IP is hyperextended in a Z deformity, which is is familial

Ulnar Nerve Deformities

• Bishop's Hand (Benediction Hand): Occurs at rest. Loss of lumbricals leads to digits 4 & 5 resting opposite the lumbricals' action.
• Claw Hand: Occurs at rest. Similar to Bishop's hand but may have some abduction of digits 4 & 5.
• Froment's Sign: Active. Loss of the adductor pollicis (innervated by ulnar nerve) leads to compensatory recruitment of the flexor pollicis longus (median nerve)

Median Nerve Deformities

• Ape Hand: Occurs at rest. Thenar wasting causes the thumb to rest in line with other digits with inability to oppose or flex thumb.
• Oath Hand: Active. Unsuccessful attempts to make a fist, ulnar digits 4 & 5 flex while median digits 1, 2, 3 do not.

Claw Fingers

• Is categorized under both Median and Ulnar combined nerve damage
• Fingers are often hyper-extended at the MCP joints and flexed at the interphalangeal joints, the
• Patients cannot cup hand

Radial Nerve Deformities

• Wrist Drop: Occurs at rest. Loss of extensors leads to flexed wrist and fingers with inability to extend wrist or fingers.

Carpal Tunnel Syndrome

• Median nerve compression: Decreased space in tunnel or increased contents; external pressure on wrist
• The hallmark sign is nocturnal pain, especially in digits 1-3, as opposed to the skin over the thenar eminence
• Differentiate from pronator teres as alternate compression site.

Dupuytren's Contracture

• Affects the palmar fascia with 3 layers (longitudinal, transverse, vertical). Palmaris longus inserts into palmar fascia.
• It is slowly progressive with no effect on tendon, muscle, or joint.
• Signs: Tender, thick, nodular palmar fascia and MCP & IP joints stuck in flexed position with digits 4 & 5 affected.
• Treat with heat, MFR, and stretching.

Skier's Thumb/Gamekeeper's Thumb

• This is a sprain of the ulnar collateral ligament (UCL) of the first MCP joint.
• The MCP joint sits between mobile CMC and rigid IP joint.
• UCL dysfunction may result from acute trauma or repetitive stress.
• The thumb's ulnar-sided MCP will be painful at digit 1, with gripping and pinching being difficult and painful
• Additionally, there will be a positive UCL stress test.

Flexor Pollicis Longus Tenosynovitis

• The tendinous sheath of the FPL extends from radial & superficial extending to the carpal tunnel before angling around the scaphoid to thumb.
• The site is a potential location of irritation to the FPL sheath
• History: Palmar thumb pain increases especially with movement that is caused by repeated thumb use

Symptoms and Differential Diagnosis

Symptoms show pain with AROM or concentric RROM but pain-free MMT Isometric contraction does not cause movement and isn't painful. Distinguish from median nerve & C6 nerve issues

1st Carpometacarpal (CMC) Osteoarthritis (OA)

• It is characterized as, a long term degenerative process; causes first CMC relative instability that predispose UCL injury of thumb
• It is characterized by thumb pain in the area of the anatomical snuffbox that gets worse during movement.
• Pain is generally worse in morning or after prolonged disuse, heat helps
• Provoking activities causes compression (radial deviation, pinching, forceful gripping),
• Pain from these types of activities can create disability and a loss of function,
• Radial nerve irritation can be a differential
• Thenar muscle MFR, stretching into abduction, & massage is helpful
• Strengthening dorsal interosseous muscle and other hand muscles is helpful

Fractures and Dislocations

• Colles fracture will show the "Dinner Fork" sign- the radius fragment will be displaced dorsally just proximal to wrist from FOOSH force.
• Galeazzi, radius fracture the distal radioulnar joint could be dislocated with complications of ulnar nerve injury
• the commonly fractured carpal occurs in the Scaphoid fracture, will be difficult diagnose by xray and commonly misdiagnosed as sprain

Trigger Finger (Digital Tenovaginitis)

• Is categorized as stenosis/ tenosynovitis
• It is induced by, Thickening of flexor tendon sheath (FDS) by Nodules along affected tendon, usually at distal MCP to palm crease

Symptoms and treatment

• When the finger is flexed, the nodule moves proximally and a palpable can be heard when the finger is extended again.
• The finger becomes locked or triggered in flexed position, sometimes a passive pull is needed to extend finger (passive)
• Idiopathic cause, increased finger flexion force, palpable lump

Finger Arthritis

• RA mainly affects the MCPs
• PIPs and DIPs (Heberden's nodes) mostly suffer from OA
• RA typically presents as hypermobile with inflammation, OA is more of hypomobile issue
• Gout should be ruled out by medical exam and joint distraction (massage) are beneficial

Wartenberg Syndrome

• Compression of the superficial radial nerve (between the ECLR and BR in the forearm) causes tingling sensation

De Quervain's Syndrome

• Includes: Abductor pollicis longus & extensor pollicis brevis. Tenosynovitis (inflammation of tendon sheath) is due to repetitive ulnar-radial deviation and forceful gripping.

Treatment

• MFR performed in anatomical snuffbox, strengthen the circumcenteric muscles (surrounding the injured muscles)

TFCC Injury

• This injury occurs with a FOOSH incident involving hyperextension or rotation injury. However, it can come slowly with repetitive stress.

Symptoms

• The injury, will be felt, deep ulnar sided in wrist, weight bearing, and can often be worse with end range pronation and extension, wrist instability
• If there is no injuries to other tissues, edema is rare in injury alone
• With all injuries immobilzing the injury is priority, and you can add bracing/compression to support wrist joint in addition to (medical management), adding light ROM and mobility to the wrist can help
• Strengthening forearm muscles and massaging those muscles supports function in the wrist by mobilizing those muscles

Home Care Principles

• Focus on strengthening weak muscles and stretching short muscles
• Creativiely strengthen different finger and limb movements
• Isolate hand muscles (no wrist movement) from extrinsic muscles if possible

Test your knowledge of wrist anatomy and biomechanics with this quiz that covers key structures, joint function, common injuries like TFCC, and the role of carpal bones. It will challenge you to identify anatomical attachments, understand wrist joint movements, and determine appropriate mobilization techniques.