Wrist complex

By
DR. SAKSHI KAUSHIK
MPT 1ST YR.
 The Wrist Complex
• The wrist (carpus) consists of two compound
joints:
• The radiocarpal and
• the midcarpal joints, referred to collectively as
the wrist complex
•  The shoulder serves as a dynamic base of
support; the elbow allows the hand to
approach or extend away from the body; and
the forearm adjusts the approach of the hand
to an object.
• The major contribution of the wrist complex
seems to be to control length-tension
relationships in the multi articular hand
muscles and to allow fine adjustment of grip.
• The wrist has been called the most complex
joint of the body, from both an anatomic and
physiologic perspective.
• The wrist complex as a whole is considered to
be biaxial, with motions of
• extension/flexion around a coronal axis
• ulnar deviation/radial deviation around an
anteroposterior axis
• Normal ranges are cited as:

• Wrist flexion 65° to 85°

• extension 60° to 85°
• radial deviation 15° to 21°
• ulnar deviation 20° to 45°
 Radiocarpal Joint Structure
• The radiocarpal joint is formed by the radius
and radioulnar disc as part of the triangular
fibrocartilage complex (TFCC) proximally and
by the scaphoid, lunate, and triquetrum
distally.
Triangular fibrocartilage complex (TFCC)
• The TFCC is essentially comprised of the
fibrocartilage disc interposed between the
medial proximal row and the distal ulna within
the medial aspect of the wrist.
• The primary function of the TFCC is to improve
joint congruency and to cushion against
compressive forces.
• The TFCC transmits about 20% of the axial load
from the hand to the forearm.
 Anatomy
The Wrist
• Comprised of the distal radius and ulna, eight
carpal bones, and the bases of five metacarpals
• The carpal bones lie in two transverse rows
 The proximal row contains (lateral to medial) the
scaphoid (navicular), lunate, triquetrum, and
pisiform .
 The distal row holds the trapezium, trapezoid,
capitate, and hamate.
 Anatomy
Mid Carpal Joints

• The midcarpal joint lies between the two rows of carpals.

• A ‘compound’ articulation because each row has both a
concave and convex segment.
 The proximal row of the carpals is convex laterally and
concave medially.
 The scaphoid, lunate, trapezium trapezoid, and
triquetrum present with a concave surface to the distal
row of carpals.
 Anatomy
Carpal Ligaments
• The major ligaments of the wrist include the intrinsic
ligaments and extrinsic ligaments.
• The extrinsic ligaments provide the majority of the
wrist stability. These joints connects carpal to radius
or ulna proximally and to metacarpals distally.
• The intrinsic ligaments serve as rotational restraints,
binding the proximal row into a unit of rotational
stability. These joints interconnects the carpals.
( INTERCARPAL AND INTEROSSEOUS LIGAMENTS)
 Anatomy
Radiocarpal Joint
• Formed by the large articular concave surface
of the distal end of the radius, the scaphoid
and lunate of the proximal carpal row, and the
TFCC.
 Anatomy
Antebrachial Fascia
• A dense connective tissue ‘bracelet’ that
encases the forearm and maintains the
relationships of the tendons that cross the
wrist.
 Anatomy
The Extensor Retinaculum
• This retinaculum serves to prevent the
tendons from ‘bow-stringing’ when the
tendons turn a corner at the wrist.
 Anatomy
• The extensor retinaculum compartments, from
lateral to medial, contain the tendons of:
• Abductor pollicis longus and extensor pollicis brevis
• Extensor carpi radialis longus and brevis
• Extensor pollicis longus
• Extensor digitorum and indicis
• Extensor digiti minimi
• Extensor carpi ulnaris
 Anatomy
The Flexor Retinaculum
• Transforms the carpal arch into a tunnel, through which pass
the median nerve and some of the tendons of the hand.
• Proximally, the retinaculum attaches to the tubercle of the
scaphoid and the pisiform.
• Distally it attaches to the hook of the hamate, and the
tubercle of the trapezium.
• In the condition known as ‘carpal tunnel syndrome’ the
median nerve is compressed in this relatively unyielding
space.
 Anatomy
Carpal Tunnel

• Serves as a conduit for the median nerve and nine flexor

tendons
• The palmar radiocarpal ligament and the palmar ligament
complex form the floor of the canal
• The roof of the tunnel is formed by the flexor retinaculum
(transverse carpal ligament)
• The ulnar and radial borders are formed by carpal bones
(trapezium and hook of hamate respectively)
• Within the tunnel, the median nerve divides into a motor
branch and distal sensory branches
 Biomechanics
• The wrist contains several segments whose
combined movements create a total range of
motion that is greater than the sum of its
individual parts.
 Biomechanics
Pronation
• Approximately 90° of forearm pronation is
available
• During pronation, the concave ulnar notch of
the radius glides around the peripheral surface
of the relatively fixed convex ulnar head
• Pronation is limited by the bony impaction
between the radius and the ulna
 Biomechanics
Supination
• Approximately 85-90° of forearm supination is
available
• Supination is limited by the interosseous
membrane, and the bony impaction between
the ulnar notch of the radius, and the ulnar
styloid process
 Biomechanics
Wrist flexion and extension
• The movements of flexion and extension of
the wrist are shared among the radiocarpal
articulation, and the intercarpal articulation, in
varying proportions.
 Biomechanics
Wrist flexion and extension
• During wrist flexion, most of the motion occurs in
the midcarpal joint (60% or 40° versus 40% or 30° at
the radiocarpal joint), and is associated with slight
ulnar deviation and supination of the forearm
• During wrist extension, most of the motion occurs
at the radiocarpal joint (66.5% or 40° versus 33.5%
or 20° at the midcarpal joint), and is associated with
slight radial deviation and pronation of the forearm
 Biomechanics
Radial Deviation
• Radial deviation occurs primarily between the
proximal and distal rows of the carpal bones
• The motion of radial deviation is limited by
impact of the scaphoid onto the radial styloid,
and ulnar collateral ligament
 Biomechanics
Ulnar deviation
• Ulnar deviation occurs primarily at the
radiocarpal joint
• Ulnar deviation is limited by the radial
collateral ligament
 Wrist Instability
• Injury to one or more ligaments attached to
the scaphoid and lunate may diminish or
remove the synergistic stabilization of the
lunate and scaphoid.
• When this occurs, the scaphoid behaves as an
unconstrained segment, following its natural
tendency to collapse into flexion on the volarly
inclined surface of the distal radius.
• The base of the flexed scaphoid slides dorsally on
the radius and subluxes.
• Released from scaphoid stabilization, the lunate and
triquetrum together act as a unconstranied
segment, following their natural tendency to extend.
• The muscular force that bypass the proximal carpals
and apply force to the distal carpals cause the distal
carpals to flex on the extended lunate and
triquetrum.
• The flexed distal carpals glide dorsally on the
lunate and triquetrum, accentuating the
extension of lunate and triquetrum.
• The zigzag pattern of three segments is known
as intercalated segmental instability.
• The scaphoid
• The lunate and triquetrum
• The distal carpal row
When the lunate assumes an extended posture, the
presentation is referred to as DISI.
• The progressive degenerative problem from an
untreated DISI is known as SLAC wrist.
SCAPHOLUNATE ADVANCED COLLAPSE
• The other common form of carpal instability occurs
when the ligamentous union of the lunate and
triquetrum is disrupted through injury.
• The lunate and triquetrum normally tends to move
towards extension and offset the tendency of
scaphoid to flex.
• When the lunate is no longer linked with triquetrum,
the lunate and scaphoid together falls into flexion,
and triquetrum with distal carpal row extend.
The ulnar perilunate instability is known as VISI.
• The problem of VISI and DISI illustrate the
importance of proximal carpal row
stabilization to wrist function and if
maintenance of the scaphoid as the bridge
between distal carpal row and two other
bones of proximal carpal row.
 Wrist musculature
•