1. Session 8 Focus on wrist and hand Anatomy – structure and function
Movements
Conditions such as Colles fracture, De Quervain’s, Carpal tunnel syndrome, OA base of the thumb, trigger finger, Dupuytren’s contracture and more!

4. Bones of the wrist
The wrist is a vital link in the upper limb for hand function
Lost function cannot be replaced by the shoulder or elbow
Its main function is to make minor adjustments to grip
Made up of two compound joints radiocarpal and midcarpal
Radio carpal joint – radius and disk with the scaphoid, lunate and triquetrum
The proximal surfaces of the carpal bones are covered with articular cartilage
The bones are linked with interosseous ligaments
The bones together form a bi-convex surface which is flexible to adapt to the demands placed upon it
The pisiform acts as a sesamoid bone increasing the angle of pull of flexor carpi ulnaris

5. Midcarpal joint structure
Articulation between the scaphoid, lunate and triquetrum proximally and the trapezium, trapezoid, capitate and hamate distally
The scaphoid, lunate and triquetrum have convex surfaces whilst the distal row have concave surfaces
Due to the shape of the articular surfaces more extension occurs in the midcarpal whilst more flexion occurs at the radiocarpal joint

6. The wrist deconstructed
Note that the scaphoid has extensive coverage of articular cartilage making it difficult for fractures of this bone to heal
Note the hook of hamate and tubercle of the trapezium for attachment of the transverse carpal ligament. Cf later

7. Composite joints of the wrist complex
The radiocarpal joint is enclosed by a single strong capsule
The capsule of the midcarpal joint is continuous with each intercarpal articulation.
The radial collateral ligament runs from the radius and attaches to the scaphoid, trapezium and 1st metacarpal
The ulnar collateral ligament originates from the ulna inserting onto the pisiform and triqeutrum

8. Ligaments of the dorsal (back) of the wrist
The only major ligament is the dorsal radiocarpal ligament
It passes from the radial styloid to the lunate and triquetrum
It is considered to be a thickening of the joint capsule
Its main function is to maintain the lunate in contact with the radius

9. Palmar or volar radiocarpal ligament
This ligament is the most important for wrist complex motion and stability
3 bands - radiocapitate, radio-triquetral and radioscaphoid
Radio-triquetral is the strongest, it also attaches to and supports the lunate
TFCC – triangular fibrocartilage complex
Ulnocarpal ligament arises from this attaching to the lunate and capitate

10. Dorsum of wrist crossed by 9 tendons
3 primarily wrist extensors:
Extensor carpi radialis longus (ECRL), brevis (ECRB) extensor carpi ulnaris (ECU)
ECRL – from lateral supracondylar ridge to base 2nd metacarpal
ECRB – Common extensor tendon (CET) to base 3rd metacarpal
ECU – CET to base of 5th metacarpal
Extensor carpi radialis brevis is active in all grasp and release hand activities other than when performed in supination

11. Example ECRL insertion

12. Extensor retinaculum Retinaculum is a 2.5cm wide fascial band
Distal attachments to the pisiform and triquetrum
Tendon sheaths – likened to elongated bursae, lined with synovial membrane
Function is to reduce friction where the tendon passes close to bone and retinaculum

13. 6 muscles have tendons crossing the front of the wrist and can therefore produce flexion
3 main flexors are - palmaris longus, flexor carpi radialis (FCR) and flexor carpi ulnaris (FCU)
Palmaris longus – common flexor tendon (CFT) to flexor retinaculum and palmar aponeurosis Cf later
FCR – CFT to base of 2nd metacarpal + slip to 3rd metacarpal. Greater contribution to wrist flexion acting with palmaris longus than radial deviation
FCU – CFT also from ulna to pisiform and by ligaments to hamate and 5th metacarpal. Pisiform improves angle of pull so that FCU acts as flexor and effective in ulnar deviation

15. Flexor retinaculum or transverse carpal ligament
The transverse carpal ligament is attached to pisiform and hook of hamate arching over the carpal bones to attach to trapezium and scaphoid on the radial side of the palm
The area under the ligament forms the carpal tunnel cf later
Note the tendon sheaths of the finger flexors. The sheath of the little finger communicates with the common flexor sheath in the palm

16. Median and ulnar nerves in the hand
The median nerves passes through the carpal tunnel
The ulnar nerve passes through Guyons canal which is outside the carpal tunnel
Regions of the hand supplied by the nerves are shown below

17. Movements of the wrist Normal range:
Flexion is 80 – 90 degrees from neutral
Extension 70 degrees
Radial deviation 20 degrees
Ulnar deviation degrees

18. Biomechanics of flexion/extension
Movement of the radiocarpal joint is a gliding of the proximal row on the radius and radioulnar disk
Extension is initiated in the distal row with the capitate at its centre
Movement of the individual carpal bones is complex with the ligaments between the carpals acting as guy ropes and stabilisers which pull the bones together into a single unit

19. Biomechanics of radial and ulnar deviation
A radial deviation – The distal row moves radially on the proximal row until ligaments become tight and there is a bony lock
Continued radial deviation causes the carpals to move as a unit towards the ulnar
During this movement the lunate flexes and the distal carpal row extends
This allows the carpals to accommodate to the reduced space between the trapezoid and radial styloid
B ulnar deviation – active and passive forces from the ligaments move the distal row towards the ulna until the ligaments are taut
At the same time the hamate is pulled down towards the lunate which causes the proximal carpals to spread and move towards the radius
During the movement the scaphoid and lunate extend, Capitate, trapezoid and trapezium flex
Greatest ROM - wrist in neutral Flex/ext

21. Injuries to the triangular fibrocartilaginous disc and ligaments
Fractures of the wrist are common representing ¼ of all limb fractures
Children and young active people
Older people associated with falls
Colles fracture – wrist in extension, Smiths fracture wrist in flexion
More significant injuries the triangular cartilage can also be damaged +/- involvement of other ligaments
This can lead to instability of the wrist which is very disabling

22. Scaphoid fracture
Most common fractures of the carpus, accounting for 79% of all carpal fractures[3].
Most often in men aged years.
Vulnerability of blood supply therefore high risk of non-union and avascular necrosis with subsequent osteoarthritis; early diagnosis and treatment minimise these risks.
Usually associated with fall onto hand or direct blow
20% fractures not seen on X-ray initially
Immobilisation, occasionally surgery, rehabilitation post immobilisation to regain wrist and hand movement and function

23. Ganglions of the wrist
Soft swelling can be associated with a joint or tendon
It is filled with thickened synovial fluid
It is not known what causes them
Traditional treatment – hit it with a heavy book to disperse the fluid. This can be successful but it may reform or you may cause other damage
Sometimes the fluid can be aspirated but again it may return
If very troublesome surgical removal may be considered

25. Carpometacarpal joints more specialised 1st CMC at the base of the thumb and 5th CMC at the base of the 5th finger to allow opposition of the tip of the thumb to tip of the 5th finger
Metacarpophalangeal joint and interphalangeal joint of the thumb
2-5 fingers MCP, proximal interphalangeal (PIP) joint, and distal interphalangeal joint (DIP)

26. CMC joint of the thumb Proximal surface of the trapezium saddle shaped
Palm upwards thumb in line with the index finger trapezium convex medial to lateral
This allows the thumb to:
Stretch outwards into extension, flex across the palm,
Bring the tip of the thumb to the tip of the little finger – opposition
Lie flat along the palm in line with the index finger – adduction
Stretch directly away from the index finger - abduction

27. Ligaments of the CMC joint
The capsule of the joint is relatively lax to accommodate movement
It is reinforced by radial, ulnar, volar and dorsal ligaments
There is also an intercarpal ligament tethering the bases of the 1st and 2nd metacarpals together

29. Movement at the saddle joint in abduction
With the thumb flat to the palm in line with the index finger movement away from the palm – abduction occurs whilst the convex surface on the base of the metacarpal slides backwards in the saddle. See cowboy below

30. Movement at the saddle joint in flexion/extension
Starting position of the thumb as before, moving the thumb down and away from the index finger into extension
The concave surface on the base of the Ist metacarpal moves over the trapezium in the same direction as the carpal bone
There is also some lateral rotation of the shaft of the metacarpal
Flexion, taking the thumb across the palm occurs with medial rotation
Note the cowboy leaning side to side in the saddle

31. Opposition of the thumb
Opposition of the thumb occurs with greater axial or medial rotation of the metacarpal to matched by flexion and rotation of the 5th metacarpal to bring the tip of the thumb and finger together

33. Ext pollicis longus and brevis
Longus – middle 1/3 posterior ulna to base of distal phalanx thumb
Action - extends the tip of the thumb, assists with extension MCP and CMC joints of thumb
Brevis – posterior radius to base of proximal phalanx of thumb
Action – extends the MCP joint of the thumb,

34. The intrinsic muscles of the thumb particularly flexor and abductor pollicis form the thenar eminence
Flexor pollicis brevis flexes the MCP and CMC joints. It assists in opposition of the thumb towards the little finger

35. Abductor pollicis longus – from the posterior surfaces of the radius and ulna and the interosseous membrane to the base of the first metacarpal
Action – abducts and extends CMC joint of thumb
Abductor pollicis brevis – flexor retinaculum, trapezium and scaphoid to base of the proximal phalanx of thumb and extensor expansion. Cf later
Action – abducts the CMC and MCP joints. Via the dorsal expansion extends the tip of the thumb

36. Adductor pollicis
Transverse fibres – palmar surface 3rd metacarpal to base proximal phalanx
Oblique fibres – capitate, base 2nd and 3rd metacarpals to extensor expansion
Action – adducts the CMC joint, adducts and assists in flexion of the MCP joint

40. OA CMC joint of thumb
1 in every 6 people consulting for help with arthritis have it in their wrist or
1.56 million people*, 6% of people aged 45 and over*
620,000 working-age women in the UK (45–64 years).*
More women than men likely to seek treatment
Women aged 45–64 twice as likely than men to seek treatment
Management – rest, ice or heat, NSAIDs
Splinting may help when undertaking activities
Must take it off and exercise thumb to avoid additional stiffness
Sometimes a trapeziectomy may be considered, arthrodesis, joint replacement, interposition of soft tissue into the joint space
Discussion with the surgeon with particular emphasis on outcome and complications

41. De Quervain’s (stenosing) tenosynovitis
Pain and swelling radial side of thumb and wrist
Worse with thumb and wrist movement, associated with overuse and repetitive movement
Reduced sliding of the tendons of extensor pollicis brevis and abductor pollicis longus where they run over the styloid of the radius and below the extensor retinaculum
Pain on extending the thumb, also when stretching the tendon, thumb flexed across the palm, wrist in ulnar deviation
Rest, ice, splinting, NSAIDs, if not resolving steroid injection

42. Gamekeepers thumb
Used to be associated with gamekeepers wringing the necks of birds between the thumb and index finger
Now more often associated with skiing injury, falling whilst holding a ski pole
Fall onto the hand whilst holding a stick
Partial or complete tear of the ulnar collateral ligament leading to instability of the thumb
Important to get treatment early – referral to hand surgeon for consideration of surgery

43. Metacarpophalangeal joints
4 MCP joints of the fingers – convex metacarpal head, concave base of first phalanx distally
The metacarpal has 180 degrees of articular surface. Note the greater excursion towards the palm of the hand to facilitate finger flexion
The capsule is lax in extension
The volar plate is a fibrocartilaginous structure which blends with the capsule and it also blends with the transverse metacarpal ligament
The volar plate helps to limit extension it also prevents pinching of the flexor tendons
The collateral ligaments provide side to side stability of the joint
They are tight when the fingers are flexed

44. Proximal and distal interphalangeal joints
PIP and DIP joints formed of the head of the phalanx and the base of phalanx distal to it
IP joint synovial hinge joint – joint capsule, volar plate and two collateral ligaments

45. Extensor digitorum Longus – CET, insertion via 4 tendons into the dorsal digital expansion
Over the proximal phalanx the tendon splits into a medial and 2 lateral bands
The medial band inserts into the base of the middle phalanx
The lateral bands reunite over the middle phalanx and insert into the base of the distal phalanx
Extensor indicis has a separate muscle belly from the posterior ulna inserting into the extensor expansion
Extensor digiti minimi – CET to extensor expansion of the little finger

47. Splitting of flexor digitorum superficialis tendon with flexor digitorum profundus tendon inserting into the terminal phalanx

48. MCP joint flexion/extension
The range of flexion at the MCP joint increases from 90 degrees at the index finger to 110 degrees at the little finger
Hyperextension is consistent between fingers but varies considerably between individuals
The range of ab and adduction is greatest in extension
The index and little fingers have the greatest range of ab and adduction
Note the A1 and A2 pulleys which prevent the flexor tendons from bowstringing outwards

49. Flexion at the PIP and DIP joints
In the index finger the greatest range of flexion extension is at the PIP joint ( degrees)
At the DIP joint the range is 80 degrees
The range of motion at each joint increases towards the little finger where PIP joint flexion is 135 degrees and DIP joint flexion reaches 90 degrees
The increasing range towards the ulnar side of the hand angles the fingers towards the thumb
Grip is therefore tighter on the ulnar side of the hand

50. Fibro-osseous tunnels
To prevent the flexor tendons from bowstringing out from the phalanges there are a number of fibrous tunnels A1, A2 etc pulleys
To prevent excessive friction the tendons are enclosed in a tendon sheath containing synovial – like fluid which promotes sliding of the tendon

51. Lumbrical muscles Lumbricals
Ist and 2nd lumbricals arise from the radial side of the profundus tendon
3rd and 4th arise from the adjacent sides of the tendon
Insert into the radial side of the digital expansion
Action – Extends the IP joints and simultaneously flexes the MCP joints

53. Insertion of the lumbricals and dorsal interossei into the extensor expansion

55. Entrapment of median nerve as it passes through the carpal tunnel at the wrist.
Often cause unknown, may be associated with flexor tendinitis, wrist arthritis (especially inflammatory arthritis), previous Colles' fracture, pregnancy, hypothyroidism, diabetes, obesity
Incidence peaks in the late 50s, particularly in women, late 70s men and women =
Pain and tingling thumb, index, middle ½ of ring finger worse at night
Severe cases wasting of the muscles of the thenar eminence, weakness of grip
Sustained wrist flexion may reproduce the symptoms, tapping over the front of the wrist
Treatment with resting splints at night
Review of work station if excessive keyboard usage may be a contributing factor
Steroid injection may resolve the problem

56. Carpal tunnel release
If conservative measures fail surgery may be indicated
If diagnosis uncertain nerve conduction studies may be requested
Surgery involves cutting the transverse carpal ligament
This can be performed as an open procedure or endoscopically

57. Heberden’s nodes Swelling of the DIP joint associated with arthritis
Thought to be hereditary in 40-60% of cases
Management – ice, heat, maintaining flexibility, avoiding over-stressing the joints

58. Mallet finger
Rupture of the extensor tendon to the terminal joint of the finger
Direct blow to the finger, stubbing the finger as in making the bed
Mallet finger splint 6 weeks
Ensure that when removed for washing the finger is held in extension so that the ends of the tendon remain in apposition

59. Trigger finger
Nodule in the flexor tendon with constriction of the A1 pulley
Usually the ring or middle fingers affected
The finger is often stuck in flexion in the morning and makes a popping sound as the finger is extended
A steroid injection can relieve the problem in 70% of cases
If after 2 injections the problem is still significant referral for surgery is indicated

60. Structure of the aponeurosis or fascia of the hand

61. Dupytrens contracture
Progressive disorder affecting palmar fascia, causing the fibrous tissue to shorten and thicken.[1] 
Excessive myofibroblast proliferation, altered collagen matrix composition, thickened and contracted palmar fascia. The resultant digital flexion contractures may severely limit function
Typically affects northern European men over age 60, 25% prevalence
6x more common in men
Genetic component, trauma, inflammatory response, environmental
Smoking, diabetes, excessive alcohol
Management – not all come to surgery, early stages injectable, collagenase appears to be equivalent to surgery; however, recurrence rates are still an issue, reported as 47% at five years.

63. Following immobilisation for a wrist fracture it is important to regain all the movements of the wrist
Passive stretching using the other hand or the positions shown in the diagrams
Using a hand weight helps to strengthen the wrist flexors and extensors and the muscles of pronation and supination

64. After a hand injury it is important to regain all the movements of the fingers and thumb particularly flexion of the tip of the finger as well as at the IP and MCP joints
An elastic band around the base of the little finger and over the thumb can be used to strengthen extension
Laying the thumb inline with the index finger the band can resist abduction
Used just around the fingers resists finger abduction

65. Next week Spine – mainly cervical but some thoracic
Anatomy structure and function
Disc degeneration, OA facet joints, nerve root irritation, spinal stenosis, whiplash
Presentation and management of conditions