OT543: Kinesiology Exam 2C

What are the Components of the Wrist?

"Functional Unit" of:

-Distal Radius & Ulna

-8 Carpal Bones

-Proximal Metacarpal Bones

-Soft Tissue Structures

What is the Purpose of the Wrist "Unit"?

-Position the hand (for grasp/dexterity)

-Increases the mechanical advantage of the hand muscles (ex Tenodesis Action)

Distal Radioulnar Joint

(Pivot Joint)

between head of ulna & ulnar notch of radius

-loose, surrounding capsule allows for pronation/supination

-stability via ligaments & interosseous membrane

Triangular Fibrocartilage Complex (TFCC)

Complex structure comprised of radioulnar disc & fibrotic attachments that provide primary support for the distal radioulnar joint

-located on the medial aspect of the wrist

---cushion between the ulna & carpal bones

-disruption can impact the ulna/ulnar side

-functionally considered an extension of the radioulnar joint & the distal radius (articular surface)

Radiocarpal Joint

(Condyloid Joint)

Where the distal radius articulates with the proximal row of carpal bones

-50% of wrist motion occurs here

-Consists of:

---Radius

---Radioulnar Disc

---Scaphoid

---Lunate

---Triquetrum

-Motions: Flexion/Extension & Radial/Ulnar Deviation

-Ligaments: Ulnar & Radial Collateral (anterior & posterior)

Midcarpal Joint

(Plane/Gliding Joint)

(Functional unit rather than anatomical)

Between the proximal & distal carpal rows

-Motions: ALL motion; but mainly Extension & Radial Deviation

-Ligaments for stability including the Transverse Carpal Ligament

What do the Midcarpal & CMC Joints Form?

The arches of the hand

What Carpal Bones are in the Proximal Row?

-Scaphoid

-Lunate

-Triquetrum

-Pisiform

What Carpal Bones are in the Distal Row?

-Trapezium

-Trapezoid

-Capitate

-Hamate

Carpal Movement in Wrist Flexion

Proximal carpal row glides POSTERIORLY

Carpal Movement in Wrist Extension

Proximal carpal row glides ANTERIORLY

Carpal Movement in Radial Deviation

Proximal carpal row glides ULNARLY

Carpal Movement in Ulnar Deviation

Proximal carpal row glides RADIALLY

Which Carpal Row has the Most Movement in Flexion/Extension?

Proximal Row

Ulnar Positive Variance

The ulna is TOO LONG

-possible TFCC Impingement

---causes pain when loading wrist & during ulnar deviation

Ulnar Negative Variance

The ulna is TOO SHORT

-Kienbock's Disease

---when the lunate collapses & dies (avascular necrosis) from taking ALL the pressure

What are the 2 Volar Carpal Ligaments?

1) Scapholunate Interosseous Ligament

2) Luntoriquetral Interosseous Ligament

Scapholunate Interosseous Ligament

Responsible for wrist stability, as it stabilizes the scaphoid

-hooks the scaphoid to the lunate

-Scaphoid Instability: common wrist issue

Luntoriquetral Interosseous Ligament

Stability between the lunate & triquetrum

-Avascular: can contribute to lunate instability

Dorsal Radiocarpal Ligament

Connects radius to posterior scaphoid & lunate

-contributes to wrist stability- especially of the scaphoid during wrist ROM

-TAUT in wrist flexion

---keeps carpal bones in place

Capitate Bone

Considered the CENTER of wrist motion ("KEYSTONE")

-LARGEST carpal bone

Lunate Bone

Moves the LEAST in flexion/extension

Scaphoid Bone

Links the proximal & distal carpal rows

-important for stability

-MOST MOTION of carpal bones during wrist flexion/extension

**Source of COMMON wrist injuries

Functional Movement of the Wrist

(FULL Flexion to Extension)

Movement initiated at the distal carpal row & metacarpals by the wrist extensors

-DISTAL carpals glide ON the PROXIMAL carpals

At Neutral: Close-Packed Position of the Scaphoid & Capitate

(Complete Wrist Extension)

Proximal carpals move as ONE unit on the radius & TFCC

-Ligaments taut in FULL extension = Full Close-Packed Position

Carpal Joints in Radial & Ulnar Deviation

Reciprocal motion of the proximal row in RD & UD

-MOST ROM = Neutral Position

-Proximal Row: simultaneous flexion of the proximal carpals & extension of the distal carpals during RD also occurs

-Scaphoid Flexion: related to ligament laxity

-Full Radial Deviation: radiocarpal & midcarpal joints are close packed

-Extreme Flexion or Extension: little radial/ulnar deviation available

What are the Most Important Motions for Function?

-Wrist Extension

-Ulnar Deviation

Wrist ROM for Most ADLs (functional requirements)

-Flexion: 54°

-Extension: 60°

-Ulnar Deviation: 40°

-Radial Deviation: 17°

What is the Primary Roles of the Wrist Muscles?

-Provide a stable base for the hand

-Position hand for optimal length-tension relationship in the long finger muscles

Wrist Flexor Work Capacity

MORE than TWICE than that of extensors

-but the wrist can position the extensors to have a mechanical advantage

Are Flexors or Extensors Stronger?

Flexors

Proximal Transverse Arch

(aka. Carpal Arch)

Formed by the distal row of carpal bones

-arch right above wrist on the palm side

-forms the "Carpal Tunnel"

Contains:

-Median n.

-9 Extrinsic Flexor Tendons

Distal Transverse Arch

Found at the level of the MCP joints

Longitudinal Arch

Begins at the wrist & runs the length of the metacarpals & phalanges for each digit

Drop Wrist

Radial n. Palsy

-CAN'T extend wrist

Claw Hand

Ulnar n. Injury

-CAN'T do the intrinsic plus position

Ape Hand

Median n. Injury

-wasting of the thenar eminence

-flat hand/palm (lack of opposition)

---less prominent arches

Distal Palmar Crease

Transverse crease that start at the medial side & goes between index & middle fingers

**MP Flexion**

Proximal Palmar Crease

Transverse crease commencing on the lateral side of the palm, extending medially & fading out on the hypothenar eminence

**Middle crease**

Thenar Crease

Crease around the thenar eminence

Thumb Motion: opposition, CMC, & palmar abduction

CMC Joints of the Fingers

Between the carpals & metacarpals

-Index & Middle Finger = STABILITY

-Ring & Small Finger = MOBILITY

Order of Most -> Least Mobile CMC Joints

5, 4, 2, 3

Thumb CMC Joint

(Saddle Joint)

Trapezium meets the metacarpal

-EXTREMELY MOBILE

Motions:

-Flexion/Extension

-Radial & Palmar Abduction/Adduction

-Rotation

-Opposition

-Circumduction

When are the Thumb CMC Ligaments Taut?

Abduction/Adduction

MP Joints of Fingers & Thumb

(Diarthrodial (biaxial)/Condyloid) = MOBILITY

-Radial Side = LESS ROM

-Ulnar Side = MORE ROM

MP Joint Collateral Ligaments

On BOTH sides

-Taut in flexion which limits abduction/adduction

MP Joint Capsule

-Taut in Flexion

-Lax in Extension

Ulnar Collateral Ligament Injury of Thumb

(Skier's Thumb)

Forced hyperextension and/or hyperabduction stress to the thumb MP joint

-occurs 10x MORE often than radial collateral injuries

-results in thumb instability

Radial Collateral Ligament Injury of Thumb

Disruption results in pain during ADDucted activities (ex. opening jar)

What Type of Joints are the PIPs or Thumb IP?

Synovial Hinge Joints

PIP/IP Collateral Ligaments

Taut in flexion OR extension

-important for STABILITY

-RADIAL = MORE likely to be injured

What is the Strongest PIP Collateral Ligament?

RADIAL Collateral Ligament of INDEX FINGER

-used for key pinch

What Type of Joints are the DIPs?

Hinge Joints

What is the Function of the Fascia at the Wrist?

Prevents bowstringing & INCREASES the mechanical advantage

Deep Transverse Ligament

Part of the flexor retinaculum

-incised during carpal tunnel release

Intercarpal Ligaments

Connect the carpal bones

-contribute to the carpal tunnel

"Pulley" System of the Digits

Fibrous Digital Sheath

-Annular Ligaments:

---5 per digit

---3 at each thumb

-Cruciate Ligaments:

---4 per digit

---2 at each thumb

A1 Pulley

Band of tissue holding flexor tendon closely to finger bones, near palm

- responsible for trigger finger

Optimal Splinting Positioning to Prevent Deformity

Wrist Extension: 15-20°

MP Flexion: 70-80°

IP/DIP/PIP Extension: 0° (full extension)

Thumb: always leave FREE unless it needs to be included then:

---Palmar Abduction

Flexor Tendon Zones

5 Different Zones:

Zone 1: Distal to Flexor Digitorum Superficialis insertion

Zone 2: A1 Pulley to Flexor Digitorum Superficialis insertion

Zone 3: Distal end of the Carpal Tunnel to A1 Pulley

Zone 4: Within the Carpal Tunnel

Zone 5: Proximal to the Carpal Tunnel

3 Thumb Zones:

-Zone 1: Distal to IP joint

-Zone 2: Between the MP & IP joints

-Zone 3: Thenar Eminence

What is Significant About Flexor Zone 2?

("No Man's Land")

-HIGH risk for tendon adhesions

What is Significant About Flexor Zone 5?

("Spaghetti Wrist")

-severe, multi-structural lacerations of the palm side of the wrist

Extensor Tendon Zones

8 Different Zones:

-Zone 1: DIP joint

-Zone 2: Middle Phalanx

-Zone 3: PIP joint

-Zone 4: Proximal Phalanx

-Zone 5: MP joint

-Zone 6: Metacarpal

-Zone 7: Dorsal Retinaculum

-Zone 8: Distal Forearm

5 Thumb Zones:

-Zone 1: IP joint

-Zone 2: Proximal Phalanx

-Zone 3: MP joint

-Zone 4: Metacarpal

-Zone 5: CMC joint/Radial Styloid

What Tendon is Injured the Most in Extensor Zone 1?

Extensor Digitorum

Extensor Expansion

Specialized connective tissue structure by which the extensor tendons insert onto the phalanges

AKA:

-Extensor Aponeurosis

-Extensor Hood

-Extensor Mechanism

-Dorsal Hood

Central Band/Central Slip

Inserts into the base of the MIDDLE phalanx

-is an extension of the Extensor Digitorum & Interossei

-EXTEND the PIP joints

Lateral Bands

Inserts into the base of the DISTAL phalanx

-is an extension of the Extensor Digitorum, lumbricals & Interossei

-EXTEND the DIP joints

Retinacular "Link" Ligaments

They pass ANTERIOR to the PIP joint axis & POSTERIOR to the DIP joint axis

-they "link" the PIP & DIP joint motions

---if the DIP is flexed, it becomes taut & the PIP tends to flex

------if the PIP is extended, it becomes taut & the DIP is extended

What is the Main Function of the Extensor Mechanism?

EXTENDS PIP & DIP joints

Extensor Mechanism Summary

-When the PIP extends, the DIP extends

-DIP cannot actively extend with PIP flexed

- When the DIP actively flexes - the PIP actively flexes

-Simultaneous MP, PIP, & DIP flexion = use ALL available extensor mechanism slack

Swan Neck Deformity

PIP extended & DIP flexed

-lateral bands slide POSTERIOR

Boutonniere Deformity

PIP flexed & DIP extended

-lateral bands get too short/tight & slide ANTERIOR

Boxer's Finger

Fracture of the 5th Metacarpal

-common when striking something with a closed fist

-can be treated with a closed reduction or surgically

CMC Osteoarthritis

Arthritis of the CMC joint

-more common in women

Symptoms:

-thumb pain at CMC joint

-positive grind test

-achy wrist

Trigger Finger

Pathologic thickening of the flexor tendon sheath

-Most Common at the A1 pulley , FDS

---Thumb FPL

-Most Common Digits:

---Thumb

---Ring Finger

---Middle Finger

SLAC Wrist

Scapholunate Advanced Collapse

-form of scapholunate instability

DISI Wrist

Dorsal Intercalated Segment Instability

-form of scapholunate instability (tear of the ligament)

-Lunate tilts posteriorly

-Dorsiflexion Instability

VISI Wrist

Volar Intercalated Segment Instability

-volar rotation of the scaphoid & lunate w/ extension of the triquetrum w/ lunotriquetral instability (tear of the ligament)

----Lunate tilts anteriorly

What is the Functional Position of the Hand & Wrist?

-Forearm in Midposition

-10° of Ulnar Deviation

-20° of Wrist Extension

-MPs are Slightly Flexed & Abducted

-Thumb is Abducted & in Slight Opposition

-IP/DIPs are Flexed

Prehension

Grasping or taking hold of an object between any 2 surfaces

-power grip OR precision handling

Power Grip

General term to describe ALL gripping

-OR full grip which includes the thumb

Includes:

-Cylindrical Grip

-Spherical Grip

-Hook Grip

-Lateral Prehension

Cylindrical Grip

ALL fingers flexed around the object

-Thumb & fingers in opposite direction

-Ex: holding a cup

Spherical Grip

All fingers & thumb adducted around an object

-Fingers spread apart

-Palm is often not involved

-Ex: holding a ball

Hook Grip

Thumb NOT included

-looks like intrinsic minus position

Lateral Prehension

Thumb pad to lateral surface of index finger

-"KEY PINCH"

What is the Optimal Wrist Position for Power Grip?

-20° of Extension

-5° of Ulnar Deviation

**In this position the Index & Middle Fingers each absorb approximately 32% of the force

When is Grip the Least Powerful?

40° of WRIST FLEXION

What are the 3 Types of Precision Handling?

-Pad to Pad

-Tip to Tip

-Pad to Side

Pad to Pad Prehension

Opposition of pad of thumb to pad of finger

-Tripod Pinch

-Palmar Pinch

Tip to Tip Prehension

Tip of thumb against tip of index finger

-Tip Pinch

-Pincer Pinch

Pad to Side Prehension

Tip of thumb to side of index finger

-LEAST precise type

-Key Grip

-Key Pinch

-Lateral Pinch

What is the Best Way to Measure Edema for the Entire Wrist/Hand?

Volumeter

Tap or Percussion Test

Patient sitting/standing with forearm resting on table & affected finger extended

--examiner taps end of finger

Positive Test = Fracture

--pain at the injury site

Compression Test

Patient sitting/standing with forearm resting on table & affected finger extended

--examiner holds distal phalanx & applies compression DOWN

Positive Test = Fracture

--pain at the injury site

Long Finger Flexion Test

Patient sits with forearm supinated & resting on table

--examiner stabilizes all NONTEST finger & has the person flex both PIP & DIP

Positive Test = Flexor Digitorum Superficialis/Flexor Digitorum Profundus and or Nerve Compromised

--unable to flex the PIP/DIP joints

Finkelstein Test

Patient sits/stands & forms a first around thumb with forearm in neutral position

--examiner pushes down on hand while supporting forearm

Positive Test = DeQuervain's

--pain on the radial side of the wrist

Phalen Test

Patient sits/stands with elbow extended & forearm pronated

--examiner pushes hand DOWN into flexion & holds for 1 minute

Positive Test = Carpal Tunnel Syndrome

--numbness/tingling on the median n. distribution of the fingers

Reverse Phalen Test

Patient sits/stands with elbow extended & forearm pronated

--examiner pushes hand UP into extension & holds for 1 minute

Positive Test = Carpal Tunnel Syndrome

--numbness/tingling on the median n. distribution of the fingers

Tinel's Sign

Patient sits with forearm supinated & resting on table

--examiner taps over the carpal tunnel

Positive Test = Carpal Tunnel Syndrome

--tingling, paresthesia, or pain in the area of the median n. distribution of the fingers

Froment's Sign

Patient sits/stands & holds a piece of paper between their thumb & index finger

--examiner tries to pull paper out

Positive Test = Ulnar n. Compromise

--flexion of the distal IP joint of the patient's thumb