Forearm Flashcards
What runs around Lister’s tubercle?
EPL tendon
1 carpal fracture? Risks?
Scaphoid, risks of nonunion/AVN
Which bone articulates with the triangular fibrocartilage complex (TFCC)
triquetrum
Which tendon does the trapezium have a groove for?
FCR
Scaphoid lunate angle average?
47° (range 30°-60°)
Monteggia fracture. Complications?
Proxima ulna fracture characterized by anterior angulation of ulna and anterior dislocation of radial head Complications: Radial nerve/PIN injury. Compartment syndrome
Galeazzi fracture
Distal 1/3 radial shaft fracture with distal RU dx. May be anterior or posterior.
Colles fracture
Distal radial head fracture with dorsal angulation
Frykman classification
I: extraarticular radius II: I+ulnar styloid III: Radiocarpal intraarticular IV: III+ Ulnar stuloid V: Intraarticular distal radioulnar VI: V+ulnar styloid VII: Intraarticular radiocarpal and distal radioulnar VIII: VII+ ulnar styloid
Most common scaphoid fx location? Complications?
Middle/waist followed by proximal pole and distal pole Complications: Osteonecrosis, nonunion, SLAC (scaphoid lunate advance collapse)
Mayfield classification
Perilunate instability I: Scapholunate disruption II: lunocapitate disruption III: Lunotriquetral disruption IV: lunate (peri) dislocation
Dislocation of lunate occurs through?
Space of Poirier
Torus fracture?
Buckle fracture of radius
Greenstick fracture?
concave, cortex intact or buckled.
Are palmar (volar) or dorsal hand ligaments stronger?
palmar
Radiocarpal joint: Superficial ligaments
RSC (RS and RC) long RL UC
Radiocarpal joint: Deep ligaments
short RL UL (help stabilize the DRUL) ulnotriquetral (“”) RSL (ligament of Testut)
Radiocarpal Extrinsic - dorsal
Dorsal RC (superficial and deep bundles)
Contents of the carpal tunnel?
9 tendons: 4 FDS 4 FDP 1 FPL 1 nerve: Median n
Primary fxn of triangular fibrocartilage complex?
Stabilizes the DRUJ
Borders of carpal tunnel?
Roof: transverse carpal ligament (flexor retinaculum) Floor: central carpal bones Medial wall: pisiform and hamate Lateral wall: trapezium and scaphoid
Borders of ulnar tunnel/Guyon’s canal
Floor: TCL Roof: volar carpal ligament Medial wall: pisiform Lateral wall: hook of hamate
Contents of the ulnar tunnel
Ulnar nerve and artery
1 cause of ulnar tunnel nerve compression?
Ganglion cysts
Extensor compartments of the wrist 1-6?
1: APL, EPB 2: ECRL, ECRB 3: EPL 4: EDC/EI 5: EDM 6: ECU
deQuervain’s tenosyovitis
pain in the first extensor compartment
Phalen’s test
flex wrists for one minute, median nerve tingling=positive
Durkan carpal compression
manually compress the median nerve at carpal tunnel. Reproduction=positive. most sensitive test
Tinel test
tap volar wrist. tingling=CTS
Finkelstein test
Flex thumb and ulnar deviate wrist. Pain in 1st dorsal compartment= de Quervain’s
Piano Key
stabilize the ulnar and try to translate radius. Positive = DRUJ instability
Watson test
Scaphoid shift. Push dorsally on pole of scaphoid, bring wrist from ulnar to radial deviation. Click/clunk = carpal instability
Allen test
Occlude both radial and ulnar arteries, release one artery only. Absence of pinking suggests arterial compromise.
First layer forearm flexors (superficial)
1: Pronator teres 2: FCR 3:PL 4:FCU
Second layer forearm flexors (middle)
FDS
Action of FDS
PIPJ flexion
Action of FDP
DIPJ flexion
Third layer forearm flexors (deep)
1:FDP 2:PQ 3:FPL
AIN innervates? AIN test
Deep flexors (1/2 FDP, PQ, FPL) Make the “OK” sign
Where does ulnar nerve run in forearm
Between FDS and FDP, ulnar to the artery
Where does superior branch of radial nerve run in forearm
Runs under brachioradialis tendon/muscle, radial to the artery
Where does median nerve run in forearm?
Between FDP and FPL into carpal tunnel
Where does PIN start? Run?
Starts after radial nerve pierces the supinator. Runs between APL and EPL along IO membrane.
What innervates the capsule of extensor compartment 4?
PIN
Where does the MC nerve run in arm?
Between biceps and brachialis, runs in subcutaneous tissues above the brachioradialis.
Where does ulnar nerve run in forearm?
Exits cubital tunnel then through the FCU heads.
Classes of TFCC tears?
1: traumatic (repair) 2: degenerative (conservative)
Pronator syndrome caused by?
Caused by median nerve compression
Places median nerve can be compressed proximally?
1: ligament of Struthers 2: Pronator teres 3: Lacertus fibrosis 4: FDS aponeurosis/arch
PIN syndrome, compression sites (5)
1) Fibrous bands 2) Leash of Henry 3) ECRB 4) Arcade of Frohse (proximal supinator edge) 5) Distal edge of supinator
Radial tunnel syndrome
Lat elbow pain, pain only, no weakness
Wartenberg’s syndrome
Compression of superficial radial nerve at wrist (b/w ERCL and BR tendons). Pain only, no weakness
Ulnar tunnel compression
Numbness/weakness in hand with atrophy. Can be zone 1 (mixed) 2 (motor) or 3(sensory)
Dissociative Carpal Instability. 2 main types
Instability within a carpal row. Two main types: Dorsal intercalated segment instability (DISI) due to SL ligament disruption or scaphoid fracture/nonunion. Volar intercalated segment instability due to lunotruquetral ligament disruption. Need RC lig injury
Nondissociative carpal instability
Instability between carpal rows. Midcarpal or radiocarpal variations
Combined carpal instability
Instability both within and between rows. Perilunate dislocation most common. Grater arc injury - transosseus injury Lesser arc injury = ligamentous injury
Scapholunate advanced collapse (SLAC), stages? spared joint?
wrist arthritis due to posttraumatic scaphoid flexion deformity. Stage 1: radial styloid + scaphoid DJD Stage 2: Radioscaphoid joint DJD Stage 3: Capitolunate joint DJD Stage 4: Capitate migration Radiolunate joint spared
Kienböck’s disease, stages
Osteonecrosis of the lunate from trauma or repetitive microtrauma. associated with ulnar negative variance of the wrist. Stage I: normal XR Stage 2: Lunate sclerosis Stage 3A: Lunate fragmented Stage 3B: 3A+scaphoid flexed Stage 4: DJD of adjacent joints
Madelung’s deformity?
Deformity of distal radius with prominence of ulnar head.
Radial club hand
Failure of formation of the radius causing bowing of the forearm and radial deviation of the hand.. Associated with VATER and TAR syndromes.
Henry approach to forearm IN plane, dangers
Anterior approach IN plane proximal: brachioradials (radial n) and pronator teres (median n) IN plane distal: brachioradials (radial n) and FCR (median n) Dangers: radial artery, superficial radial nerve, PIN.
Dorsal approach to wrist IN plane? Dangers?
No IN plane (all are PIN). 4h dorsal compartment in opened (innervated by sensory branch of PIN) Dangers: Superficial radial nerve Radial artery
Volar approach to wrist IN plane? Dangers?
IN plane proximally brachioradials (radial) and FCR (median n) Distal no IN plane Dangers: Median nerve (palmar cut. branch, motor recurrent branch), superficial palmar arch
Wrist arthroscopy portals (7)
1-2: between APL and ECRL tendons. Deep branch of radial artery, superficial radian n branches, lateral antebrachial cutaneous branches. 3-4: Between EPL and EDC. No dangers. Workhorse portal 4-5: Between EDC and EDQ. No dangers 6R: Radial side of ECU tendon. Dorsal cutaneous branch of ulnar a 6U: ulnar side of EUC. Dorsal cutaneous branch of ulnar a Midcarpal radial: 1cm distal to 3-4 along border of 3rd MC. None Midcarpal ulnar: 1cm distal to 4-5 protal in line with 4th MC. None
