Trauma and orthopaedics (6): The forearm Flashcards
forearm made up of the
Ulnar gets narrower and radius gets wider.radius and ulnar
the ulnar
- Long bone
- Lies medially and parallel to the radius
- Stabilising bone pivoting to produce movement
articulation of the ulnar
- Proximally- ulnar articulates with the humerus at the elbow joint
- Distally- articulates with the radius forming the distal radio-ulnar joint
proximal osteology of the ulnar
- Articulates with the trochlea of the humerus
- Enables movement a the elbow joint
- Important landmarks of the proximal ulnar are the :
the radius
- Long bone in the forearm
- Lies laterally and parallel to the ulnar
- Radius pivots around the ulnar to produce movement at the proximal and distal radio-ulnar joints.
articulations of the radius
-
Elbow joint
- Partly formed by an articulation between the head of the radius, and the capitulum of the humerus
-
Proximal radioulnar joint
- An articulation between the radial head and the radial notch of the ulnar
-
Wrist joint
- Articulation between distal end of the radius and the carpal bones
-
Distal radioulnar joint
- Articulation between the ulnar notch and the head of the ulnar
proximal radius
Articulates with both the elbow and proximal radioulnar joints.
distal radius
Radial shaft expands to form a rectangular end. The lateral side projects distally as the styloid process. In the medial surface there is a concavity called the ulnar notch, which articulates with the head of the ulnar, forming the distal radioulnar joint.
muscle compartment of the forearm can be split to
dont worry too much about these
anterior (superficial intermediate deep)
posterior (superficial intermdiate deep)
anterior superficial muscles of the forearm
Pass Fail Pass Fail
- pronator teres
- flexor carpis radialis
- palmaris longus
- flexor carpi ulnaris
areas of the forearm
carpal tunnel
carpal tunnel
A narrow passageway found on the anterior portion of the wrist- entrance to the palm for several tendons and the median nerve.
borders of the carpal tunnel
Formed by two layers: a deep carpal arch and a superficial flexor retinaculum. The deep carpal arch forms a concave surface which is converted into a tunnel by the overlying flexor retinaculum.
-
Carpal arch
- Concave on the palmar side, forming the base and sides of the carpal tunnel
- Formed laterally by the scaphoid and trapezium tubercles
- Formed medially by the hook of the hamate and the pisiform
-
Flexor retinaculum
- Connective tissue which forms the roof of the carpal tunnel
- Turns the carpal arch into the carpal tunnel by bridging the space between the medial and lateral parts of the arch
- Originates on the lateral side and inserts on the medial side of the carpal arch
contents of the carpal tunnel
Contains 9 tendons, surrounded by synovial sheaths and the median nerve. Palmar cutaneous branch of the median nerve is given off prior to the carpal tunnel, traveling superficially to the flexor retinaculum.
carpal tunnel syndrome
compression of the median nerve within the carpal tunnel of the wrist, due to a raised pressure within this compartment.
presentation of compression of the median nerve
pain, numbness, and paresthesia in the lateral 3½ digits.
thenar atrophy- thumb abduction and flexion
presentation of compression of the median nerve
pain, numbness, and paresthesia in the lateral 3½ digits.
worse at night
relived by hanging arm over bed or shaking back and forth
In the later stages of carpal tunnel syndrome, there may be weakness of thumb abduction (due to denervation atrophy of the thenar muscles) and / or wasting of the thenar eminence
RF for CTS
- female
- increased age
- pregnancy
- obesity
- DM
- RA
- hypothyroidism
- repetitive hand or wrist movement
why is the palm spared in CTS
due to the palmar cutaneous branch of the median nerve branching proximal to the flexor retinaculum and passing over the carpal tunnel.
why is the palm spared in CTS
due to the palmar cutaneous branch of the median nerve branching proximal to the flexor retinaculum and passing over the carpal tunnel.
special tests for CTS
tinels and phalens
investigations for CTS
clinical diagnosis
in uncertain cases- nerve conduction studies
management of CTS
conservatively
- wrist splint (stop wrist flexion)
- hand therapy
- corticosteroid injection
surgical
- when conservative treatment doesnt work
- carpal tunnel release surgery
carpal tunnel release surgery
decompresses the carpal tunnel, involving cutting through the flexor retinaculum, in turn reducing the pressure on the median nerve. This can be done under local anaesthetic and is performed as a day case.
Complications of carpal tunnel surgery
include recurrence, persistent CTS symptoms (from incomplete release of ligament), infection, scar formation, nerve damage, or trigger thumb.
distal radius fracture
occur through the distal metaphysis of the radius.
3 common types
- Colles
- Smiths
- Bartons
which distal radius fracture is most common
Colles
cause of distal radius fracture
FOOSH
The distal radius takes 80% of the axial load underneath the scaphoid and lunate fossae. A FOOSH causes a forced supination or pronation of the carpus; this in turn increases the impaction load of the distal radius.
RF for distal radius fracture
osteoporosis e.g. colles
female
early menopause
smoking or alcohol excess
prolonged steroids
(5-15yo prone too)
fractures can be articular or extra- articular
Fracture types can be described as “extra – articular” (which means the fracture line does not extend into the joint) or “intra – articular” ( which means the fracture line does extend into the joint; this is the more serious type of fracture).
Colles fracture
- extra-articular fracture of the distal radius with dorsal angulation and dorsal displacement, within 2cm of articular surface
- fragility fracture in osteoporotic bones
- FOOSH
which types of distal radius fracture are intra-articular
bartons fracture
- associated dislocation of radio-carpal joint
which types of distal radius fracture are extra-articular
Colles
Smiths (falling backwards on outstretched arm)- less common
distal radial fracture presentation
- trauma
- pain +- deformity
- +- neurovascular compromise
neurological exam after distal radial fracture
-
Median nerve: motor – abduction of the thumb; sensory – radial surface of distal 2nd digit
- Anterior interosseous nerve: opposition of the thumb and index finger*
- Ulnar nerve: motor – adduction of the thumb (‘Froment’s Sign’); sensory – ulnar surface of the distal 5th digit
- Radial nerve: motor – extension of IPJ of thumb; sensory – dorsal surface of 1st webspace
investigations for distal radial fracture
plain X-ray (AP and lateral)
Three measurements on a plain radiograph help with the diagnosis of a distal radius fracture:
- Radial height <11mm
- Radial inclination <22 degrees
- Radial (volar) tilt >11 degrees
Further CT or MRI imaging may be used in more complex distal radius fractures, particularly for operative planning, however this can be performed once initial management steps have been made.
management of distal radial fracture
- ATLS
- closed reduction in ED
- traction and manipulation under anaesthetic
- following this fracture shoud be placed in below0elbow backslab cast, then x-ray repeated after 1 week to check for displacement
- physio
- surgery if displaced or unstable
A ‘back slab’
is a slab of plaster that does not completely encircle the limb and is used for injuries which have resulted in a large amount of swelling.
surgery for distal radius fracture when
Significantly displaced or unstable fractures can require surgical intervention, as they have a risk of displacing further over time if not stabilised.
Any fracture with an intra-articular step of the radiocarpal joint >2mm is also advised to be surgically corrected.
nerve injursy that present in the hand
hand of benediction- median nerve (cant make fist)
claw hand- ulnar nerve ( can make a fist, just cant spread out hand)
what sort of median nerve injury is hand of benediction
high- median nerve damage at the elbow (fracture of humerus
- hand of benediction (more severe than lower median nerve injury)
