Hand and Microvasculature

9


Hand and Microvasculature


Eric Cohen, Byung J. Lee, and Arnold-Peter Weiss


I. Anatomy


1. Bony and articular anatomy


• Forearm


a. Osteology (Figs. 9.1 and 9.2)


Radius and ulna


Radial head is intra-articular at the elbow


Anterolateral portion of radial head has less subchondral bone, making it more susceptible to fracture


Radial tuberosity is site of biceps tendon insertion, and it points ulnarly in supination


Radial bow allows rotation around the ulna; restoration of radial bow and length is critical when fixing the radius


Radius and ulna stabilized by the proximal and distal radioulnar joints and the interosseus membrane


b. Interosseus membrane: transfers compressive load from wrist to elbow


Composed of interosseus ligament proper, proximal interosseus bands, and accessory bands


Lister’s tubercle on dorsal surface of distal radius; extensor pollicis longus (EPL) travels around Lister’s tubercle to attach to distal phalanx of thumb



Just ulnar to Lister’s is the third dorsal compartment/EPL tendon. This is also the landmark used to create the 3/4 portal for wrist arthroscopy.


c. Range of motion (ROM): supinate 80–90 degrees, pronate 75–90 degrees



About 10–15 degrees of rotation occurs at the wrist.





• Distal Radioulnar Joint (Figs. 9.3, 9.4, 9.5)



• Distal radioulnar articulation is most stable in supination.


• The ulnar sigmoid notch on the distal radius is a groove for the ulnar head and the site of the distal radioulnar joint.


a. Distal radius has two facets separated by an anterior/posterior ridge: scaphoid and lunate.




b. At the base of the ulnar styloid is the fovea, the insertion of the deep fibers of the radioulnar ligaments, which make up part of the triangular fibrocartilage complex (TFCC).


c. Only 10 to 15 degrees of pronation and supination from wrist


• Carpus


a. Radiocarpal joint (Figs. 9.6, 9.7, 9.8)


Composed of distal radius, and scaphoid, lunate, and triquetrum


Composed of volar and dorsal radiocarpal ligaments and radial and ulnar collateral ligaments



Volar radiocarpal ligaments are strongest supporting ligaments


Range of motion (Fig. 9.9)


♦ Extend ROM 75 degrees, flexion 80 degrees


♦ Radial deviation 15–25 degrees, ulnar 30–45 degrees






b. Proximal row: scaphoid, lunate, triquetrum (sesamoid, pisiform)


The proximal row has no muscular or tendinous attachments. It is an intercalary segment.



Scaphoid primary blood supply is from the radial artery at the dorsal ridge just distal to waist; proximal pole perfused in retrograde fashion


• Transverse carpal ligament attaches to the volar tubercle


a. Distal row: trapezium, trapezoid, capitates, hamate


b. Pisiform is a sesamoid bone within the flexor carpi ulnaris (FCU) tendon; also the origin for abductor digit quinti


c. Significant carpal ligaments


Scapholunate ligament: strongest dorsally, and rupture leads to dorsal intercalated segment instability (DISI) deformity


Lunotriquetral ligament: strongest volarly and rupture leads to volar intercalated segment instability (VISI) deformity


d. Carpal ossification (Fig. 9.10)


First to ossify is the capitate, at 1 year; last to ossify is the pisiform, by 12 years; ossification occurs in characteristic counterclockwise pattern


• Fingers


a. Functional position of hand (Fig. 9.11)


b. Thumb carpometacarpal (CMC) (trapeziometacarpal) joint


Saddle shaped, allowing a large degree of motion


Thumb CMC joint stabilized by capsule, dorsoradial ligament, ulnar collateral ligaments, posterior oblique and anterior oblique ligament




Primary stabilizer is anterior oblique ligament (beak ligament)


c. Finger CMC joint (Figs. 9.12 and 9.13)


Gliding joint


Stabilized by capsule, dorsal, and volar CMC and interosseous ligaments


Dorsal CMC ligament strongest


d. Metacarpophalangeal (MCP) joint


Ellipsoid, creating a cam effect on ROM


Stabilized by volar plate, collateral and deep transverse metacarpal ligaments


ROM: extend/flex 0–90 degrees, adduct/abduct 0–20 degrees (Fig. 9.14)


e. Interphalangeal (IP) joints


Hinge joint, no cam effect on ROM


Capsule and oblique collateral ligaments


ROM:


♦ Proximal interphalangeal (PIP): extend/flex 0–110 degrees


♦ Distal interphalangeal (DIP): extend/flex 0–80 degrees






2. Extensor compartments (Figs. 9.15 and 9.16) (six compartments)



• Be able to recognized which tendons are in which compartment on an axial magnetic resonance imaging (MRI)


• Covered by extensor retinaculum on dorsum of wrist


• I: Abductor pollicis longus (APL), extensor pollicis brevis (EPB)


a. De Quervain’s tenosynovitis



b. APL has multiple tendon slips; need to evaluate whether EPB has a distinct separate tendon sheath that needs to be released during surgery.


• II: Extensor carpi radialis longus (ECRL) and brevis (ECRB)


a. Intersection syndrome: at intersection of first and second compartment, often with palpable crepitus on wrist motion


• III: Extensor pollicis longus (EPL)


a. Rupture at Lister’s tubercle after distal radius fracture



b. Treat with extensor indicis proprius (EIP) to EPL transfer.


• IV: Extensor digitorum communis, extensor indicis proprius (EIP)



a. EIP is last muscle to be reinnervated in radial nerve injuries


b. Posterior interosseous nerve (PIN) is located on the floor of the fourth compartment


• V: Extensor digiti minimi



a. Vaughan-Jackson syndrome in rheumatoid arthritis, rupture of extensors in ulnar to radial direction; extensor digiti minimi (EDM) first to rupture


• VI: Extensor carpi ulnaris (ECU)


a. Pathology: can have instability at ulnar styloid




3. Tendons


• Flexor tendons


a. Flexor digitorum profundus (FDP): action is flexion at the DIP joint; FDP inserts on the distal phalanx


b. Flexor digitorum superficialis (FDS): action is flexion at the PIP joint. Prior to FDS insertion to the middle phalanx it splits to form Camper’s chiasm. The FDP travels through Camper’s chiasm to insert on the distal phalanx.


c. Flexor tendon zones (Fig. 9.17)


• Flexor tendon sheaths


a. Provide nourishment to tendons via vincula


b. Provide protection to tendon


• Pulleys


a. Five annular pulleys (A1–A5) and three cruciate pulleys (C1–C3)


b. A2, A4: arise from periosteum of P1 and P2, respectively; important to conserve to prevent bowstringing


c. A1, A3, A5: arise from volar plate of MCP, PIP, and DIP joint, respectively


d. A1 pulley involved in trigger digits


Tendon blood supply from two sources: direct vascular supply and diffusion through synovial sheath (Fig. 9.18)



In zone II (see Fig. 9.17), tendon blood supply primarily through diffusion



4. Nerves (Figs. 9.19, 9.20, 9.21)


• Median nerve (Figs. 9.22 and 9.23)


a. Travels between FDS and flexor pollicis longus (FPL) within the carpal tunnel to enter the wrist


b. Supplies sensation to the thumb, the index and middle fingers, and the radial half of the ring finger


c. Significant terminal branches


In forearm, motor branches to pronator teres, flexor carpi radialis, palmaris longus, flexor digitorum superficialis


Palmar cutaneous nerve


♦ Travels between palmaris longus and flexor carpi radialis





Palmar cutaneous nerve branches from median nerve 4 to 6 cm proximal to wrist crease, and injury may result from retraction during volar Henry approach to distal radius, causing sensory change over thenar eminence


♦ Supplies sensation to the central palm


Recurrent motor branch innervates opponens pollicis, abductor pollicis brevis, flexor pollicis brevis


Anterior interosseus nerve innervates index and middle finger flexor digitorum profundus, FPL, pronator quadrates


First and second lumbricals innervated by median nerve via branches of digital nerves






• Ulnar nerve (Fig. 9.24)


a. Enters anterior compartment of forearm through cubital tunnel and enters wrist via Guyon’s canal (Fig. 9.25)


b. Supplies sensation to the ulnar half of ring and small fingers


c. Significant terminal branches


In forearm, motor branches to FCU and ring and small finger FDP


Dorsal cutaneous branch, 5–7 cm proximal to wrist


Within Guyon’s canal, ulnar nerve bifurcates into two branches:


♦ Superficial branch is sensory branch and also innervates palmaris brevis


♦ Deep branch innervates all interossei, third and fourth lumbricals, abductor digiti minimi, opponens digiti minimi, flexor digiti minimi, adductor pollicis, and deep head of flexor pollicis brevis


• Radial nerve (Fig. 9.26)


a. Branches into deep and superficial branch in proximal forearm


b. Supplies sensation to the dorsal first webspace





c. Significant branches


Muscular branches to triceps, anconeus, extensor carpi radialis longus, brachioradialis [sometimes extensor carpi radialis brevis (ECRB)]


Posterior interosseous nerve (PIN): continuation of radial nerve; innervates ECRB, supinator, extensor digitorum communis, extensor digiti minimi, extensor carpi ulnaris, extensor indicis, abductor pollicis longus, extensor pollicis longus, extensor pollicis brevis


Superficial branch radial nerve: branches from radial nerve; emerges between brachioradialis and extensor carpi radialis longus tendon 7 cm from radial styloid to become superficial


5. Vascular


• Ulnar artery: travels radial to ulnar nerve in forearm and is primary supply to superficial palmar arch (Fig. 9.27)




• Radial artery: travels between brachioradialis and flexor carpi radialis in the forearm and is primary supply to deep palmar arch (Figs. 9.28 and 9.29)



• Digital neurovascular bundle: nerve lies volar to artery in the finger


6. Muscles


• Muscles of the hand (Figs. 9.30, 9.31, 9.32, 9.33, 9.34 and Table 9.1)


• Muscles of the forearm (Figs. 9.35, 9.36, 9.37, 9.38, 9.39, 9.40 and Tables 9.2 and 9.3)


7. Physical exam of the upper extremity


• Elbow


a. Inspection


Gross deformity or swelling may indicate fracture


Carrying angle: average 11 degrees in men, 13 degrees in women; cubitus varus < 5 degrees and cubitus valgus > 15 degrees


b. Palpation


Tender at medial epicondyle: golfer’s elbow or medial collateral ligament (MCL) pathology




Tender at lateral epicondyle: tennis elbow


Tender at radial head: fracture, arthritis


Palpate biceps tendon, absence may be due to biceps tendon rupture


c. ROM


Extend/flex ROM: 0 to 140–150 degrees


Supinate 80–90 degrees, pronate 75–90 degrees


d. Neurologic


Test motor and sensory


Reflexes: biceps C5, brachioradialis C6, triceps C7; absence or hypoactive indicates a radiculopathy


e. Special tests


Tennis elbow (lateral epicondylitis): provocative tests include resisted wrist extension



Pathology is angiofibroblastic hyperplasia of ECRB tendon


Golfer’s elbow (medial epicondylitis): provocative tests include resisted flexion and pronation; also pain at medial epicondyle with supination and extension of elbow and wrist


Radial tunnel: resisted extension of long finger


Pivot shift: The patient lies supine with arm overhead and elbow extended. The forearm is then supinated with a valgus stress applied while the elbow is flexed. If the patient exhibits apprehension or palpable subluxation of the radial head, then the test is positive for posterolateral rotatory instability.


Bicep hook test: inability to “hook” biceps due to biceps tendon rupture


Tinel’s sign: percussion of ulnar groove sends tingling or shooting pain in ulnar nerve distribution



• Wrist


a. Inspection


Gross deformity or swelling may indicate a fracture


Swelling or palpable mass at dorsal or volar aspect of wrist may indicate a ganglion cyst


Muscle wasting: thenar atrophy indicative of median nerve pathology


b. Palpation


Snuffbox tenderness may indicate a scaphoid fracture.


Tenderness at the radial or ulnar styloid or the carpal row may indicate fracture. Tenderness over the lunate may indicate Kienböck’s disease.


Tenderness distal to the ulnar styloid may indicate a TFCC tear.


Palpate extensor tendons. Tenderness over the first dorsal compartment is de Quervain’s synovitis.



c. ROM


Extend ROM 75 degrees, flexion 80 degrees


Radial deviation 15–25 degrees, ulnar 30–45 degrees


Only 10 to 15 degrees of pronation and supination from wrist


d. Neurologic


Test motor and sensory



e. Special tests


Durkan carpal compression test: manual pressure on carpal tunnel reproduces symptoms of carpal tunnel.



Most sensitive test for carpal tunnel syndrome


Phalen test: wrist flexion reproduces symptoms of carpal tunnel.


Tinel’s sign: percussion of carpal tunnel sends tingling or shooting pain in median nerve distribution.



Finkelstein test: flex thumb into palm and ulnarly deviate wrist. Pain in first dorsal compartment is suggestive of de Quervain’s synovitis.


Watson scaphoid shift: pain or a clunk with pressure applied to volar scaphoid tubercle and wrist brought from ulnar to radial deviation; compare with contralateral side; tests carpal instability due to scapholunate ligament injury


Piano key test: stabilize ulna and shuck radius dorsal/volar; subluxation or laxity indicates injury to distal radioulnar joint (DRUJ)



• Hand


a. Inspection


Gross deformity or swelling may indicate fracture.


Rotational or angular deformity of fingers may indicate facture. Rotation is assessed by having the patient make a fist; all fingers should point toward the scaphoid with no overlap of digits.


Finger position: flexed finger may be secondary to flexor tenosynovitis, tendon rupture, or Dupuytren’s contracture


Fusiform swelling of digit seen in acute infection such as flexor tenosynovitis


Swelling of DIP joint due to osteoarthritis; Heberden’s nodes


Swelling of PIP joint due to osteoarthritis; Bouchard’s nodes


Swelling of MCP joint seen in rheumatoid arthritis (RA)



Rheumatoid arthritis primarily affects the wrist and MCP joints.


Ulnar drift or boutonniere deformity seen in RA


♦ Wasting of hypothenar eminence or first dorsal webspace indicates ulnar nerve injury. Thenar wasting indicates median nerve injury.



b. Palpation


Nodules: Dupuytren’s disease, cyst, giant cell tumor of tendon sheath


Garrod’s pads: pads at dorsal PIP joint seen in Dupuytren’s disease


Tender at A1 pulley: trigger finger


Tender on volar aspect of finger at flexor tendons: flexor tenosynovitis


c. ROM


MCP: extend/flex 0–90 degrees, adduct/abduct 0–20 degrees


PIP: extend/flex 0–110 degrees


DIP: extend/flex 0–80 degrees


d. Neurovascular


Palpate brachial, radial, and ulnar artery.


Allen test (see section IX, Vascular Disorders, below, for an explanation of how to perform this test)


Assess perfusion of digits with Doppler; evaluate capillary refill < 2 seconds




Test motor and sensory


e. Special tests



Froment sign, Wartenberg sign, intrinsic atrophy, and clawing are all signs of ulnar nerve injury.


Elson test: Bend the patient’s finger 90 degrees over a table and actively extend it against resistance at the PIP joint. If the DIP joint remains supple and the middle phalanx extends, then the central slip is intact. If the DIP joint is rigid with the absence of PIP extension, then the central slip is ruptured and the lateral bands are extending the DIP.



Froment sign: IP flexion while attempting to pinch between thumb and index finger due to weak adductor pollicis (ulnar nerve); seen in cubital tunnel and ulnar nerve injuries


Wartenberg sign: abducted small finger secondary to unopposed pull of EDM and weakness of third palmar interossei (ulnar nerve); seen in cubital tunnel and ulnar nerve injuries



Jeanne sign: hyperextension of thumb MCP with key pinch by EPL (radial nerve) due to weak adductor pollicis (ulnar nerve); seen in cubital tunnel and ulnar nerve injuries


Thumb instability test: radially deviate thumb with the thumb in extension and 30 degrees of flexion to test proper and accessory ulnar collateral ligaments (UCLs), respectively.






More than 30 degrees of laxity indicates an unstable tear. In extension, stress is testing accessory collateral ligament and volar plate. In 30 degrees of flexion, stress is testing collateral ligament.


CMC grind test: axial compression and rotation of CMC joint; pain indicates CMC arthritis


Profundus test: stabilize PIP joint and flex DIP joint; inability to flex DIP joint indicates FDP injury



Sublimis test: extend all fingers and flex a finger at PIP joint; inability to flex PIP joint indicates FDS injury


Kanavel signs for flexor tenosynovitis: (1) resting flexed posture, (2) pain with passive extension, (3) fusiform swelling, and (4) tenderness volarly over tendon sheath


8. Imaging


• Elbow


a. Standard anteroposterior (AP), lateral, and oblique views


b. Traction radiographs may help delineate distal humerus fractures


c. Greenspan view evaluates radiocapitellar articulation; useful for radial head fractures; shot with forearm in neutral rotation and radiographic beam angled 45 degrees cephalad


• Forearm


a. Standard AP and lateral radiographs; oblique views useful to further evaluate fractures


• Wrist


a. Standard PA, lateral, and obliques views


b. Scaphoid view to evaluate scaphoid fractures; wrist supinated 30 degrees and in ulnar deviation



Clenched fist posteroanterior (PA) view to evaluate scapholunate ligament injury; scapholunate gap of > 3 mm indicates injury


c. Carpal tunnel view to evaluate hook of hamate fracture; shot with wrist fully extended, palm placed on cassette, and radiographic beam angled 15 degrees toward palm


d. Dorsal horizon view: wrist is hyperflexed and the beam of the image intensifier is aimed along the long axis of the radius; to search for a prominent dorsal screw from the volar plate


• Hand


a. Standard PA, lateral, and obliques views


b. Robert’s view to evaluate CMC and scaphotrapeziotrapezoid (STT) joints; pronated AP view of thumb


c. Pronated 30 degree radiographs: look for dorsal fourth/fifth CMC dislocations


9. Surgical approaches


• Forearm


a. Anterior (Henry): interval between brachioradialis (radial nerve) and pronator teres (median nerve) proximally; between flexor carpi radialis (median nerve) and radial artery distally (Fig. 9.40)


b. Posterior (Thompson): interval between extensor carpi radialis brevis (radial nerve) and extensor digitorum communis (PIN) (Fig. 9.41)


c. Ulnar: interval between ECU (PIN) and FCU (ulnar nerve)



• Wrist


a. Dorsal: interval between third (extensor pollicis longus) and fourth (extensor digitorum communis); PIN at base of fourth compartment; excise to denervate the carpus (Fig. 9.42)


b. Volar scaphoid: between flexor carpi radialis and radial artery


• Digits


a. Bruner: zigzag volar incisions across flexor crease to allow access to flexor tendons and prevent transverse scarring at flexion crease (Fig. 9.43)


b. Midlateral: lateral incision dorsal to neurovascular bundle at dorsal extent of interphalangeal crease


c. Midaxial: lateral incision centered on osseous phalanges



• Arthroscopy (Fig. 9.44)


a. Indications: TFCC tear, suspected scapholunate or lunotriquetral tear, scaphoid fracture, ulnocarpal impaction, synovitis debridement, wrist ganglion, distal radius fractures to assess joint congruency, removal of loose bodies, septic wrist irrigation and debridement


b. Portals (named for relationship to extensor compartments):


1–2 portal: risk of injury to superficial radial sensory nerve


3–4 portal: located 1 cm distal to Lister tubercle


4–5: just ulnar to the fourth compartment; should be proximal to the 3–4 portal due to radial inclination


6R: radial to ECU tendon


6U: ulnar to ECU tendon; risk of injury to dorsal sensory branch of ulnar nerve


Radial and ulnar midcarpal portals


c. Complications: nerve injury (superficial radial sensory or dorsal branch of ulnar nerve most common), MCP joint pain secondary to traction, iatrogenic tendon injury (EPL or EDM most common), infection



ECU tendon cannot be visualized arthroscopically.



II. Trauma


1. Distal radius fracture


• In elderly, distal radius and vertebral compression fractures are predictive of future hip fracture.


• Obtain dual-energy X-ray absorptiometry (DEXA) scan in women with distal radius fracture and age > 50 years.


• Associated injuries: ulnar styloid fracture, DRUJ disruption


a. Higher degree of initial fracture displacement


b. Fracture at base associated with TFCC tear


c. Open reduction and internal fixation (ORIF) of ulnar styloid only if there is associated instability of the DRUJ


• Imaging


a. Normal (Fig. 9.45)


PA radiograph: radial height, 12 mm; inclination, 23 degrees


Lateral radiograph volar tilt: 11 degrees


Comparative radiographs of contralateral wrist


b. Ulnar variance: neutral, positive, negative


c. Assess DRUJ with lateral radiograph


d. Acceptable reduction criteria: see American Academy of Orthopaedic Surgeons (AAOS) guidelines


• Classification


a. Multiple classification schemes: AO, Frykman, Fernandez, Mayo, etc.


b. Common eponyms


Smith: extra-articular volarly displaced fracture


Barton: coronal shear fracture/dislocation of radiocarpal joint


Colles: low-energy extra-articular dorsally displaced


Chauffer’s: radial styloid fracture


Die punch: depressed articular fracture of lunate fossa




• Treatment


a. Conservative management: closed reduction and immobilization


For most extra-articular distal radius fractures


Follow with serial radiographs (once a week for 3 weeks)


Total length of immobilization: ~6 weeks


Conservative management for unstable distal radius fractures in the elderly (age > 65 years) shown to have equivalent outcomes to fixation


b. Operative treatment


Indications for surgery



AAOS Clinical Practice Guidelines: operative fixation of distal radius fractures postreduction (moderate evidence); postreduction radial shortening > 3 mm, dorsal tilt > 10 degrees, intra-articular displacement or stepoff > 2 mm; early active wrist range of motion is not required with stable fixation (moderate evidence); adjuvant treatment with vitamin C (moderate evidence)


♦ Open fractures


♦ > 2 mm intra-articular displacement


♦ Volar oblique fractures


♦ Intra-articular volar shear fractures


♦ Die-punch fractures


♦ Significant dorsal comminution


Methods of fixation


♦ Closed reduction and percutaneous pinning


▪ Indicated for extra-articular unstable distal radius fractures


▪ Isolated percutaneous pinning contraindicated in fractures with volar comminution


♦ Open reduction and internal fixation


▪ Volar distal radius locking plates resist radial shortening and dorsal angulation; buttress the distal radius (biomechanically stronger than dorsal plating)


▪ Most common site of flexor tendon rupture with volar plating is the FPL; most common site of extensor tendon injury after volar plating is the EPL due to prominent screws



Dorsal horizon view ensures no dorsal prominent screw


♦ External fixation


▪ Works by ligamentotaxis


▪ Can injure sensory branch radial nerve


▪ Overdistraction can lead to complex regional pain syndrome, stiffness, and limited finger range of motion


▪ Bridge plating works as an internal external fixator with greater biomechanical advantage and similar clinical outcomes to volar plating


• Rehabilitation


a. Physical therapy compared with home exercise shows no significant difference in outcomes.


• Complications


b. Acute carpal tunnel syndrome


Most common neurologic complication; 1–12% in low-energy fracture, 30% in high-energy fracture


Decompress nerve if paresthesias are progressive or do not respond to reduction and last > 24–48 hours.


c. Ulnar nerve neuropathy with DRUJ injuries


d. Compartment syndrome


e. EPL rupture


Most common tendon rupture thought to be secondary to attrition versus local ischemia secondary to mechanical impingement


Treat with transfer of EIP to EPL


f. ECU or EDM entrapment with DRUJ injuries


g. Tenosynovitis: first and third dorsal compartments most common


h. Malunion


Revision with osteotomy, ORIF, and bone grafting at > 6 weeks


Radial shortening malunion treated with ulnar shortening osteotomy


i. Reflex sympathetic dystrophy/chronic regional pain syndrome



Vitamin C (500 mg/day) reduces risk of complex regional pain syndrome type I in patients with distal radius fractures.


2. Carpal fractures


• Scaphoid


a. Blood supply: dorsal carpal branch of radial artery enters scaphoid tubercle at dorsal tubercle (80% blood supply proximal scaphoid via retrograde flow); superficial palmar branch of radial artery enters distal tubercle and supplies 20% distal scaphoid


b. Mechanism: fall on outstretched hand with hyperextension and radial deviation of wrist


c. Presentation: snuffbox tenderness, tenderness to palpation at scaphoid tubercle (volar), pain with axial load of first metacarpal


d. Imaging


Obtain PA, lateral, and scaphoid views (30 degrees of wrist extension and 20 degree ulnar deviation)


♦ Plain radiographs may initially appear negative.


♦ If high clinical suspicion, treat with thumb spica splint and repeat X-rays in 2 weeks



MRI: most sensitive test to diagnose occult fractures within 24 hours


MRI: can evaluate location of fracture, associated ligament injuries, and vascularity


Bone scan: effective in diagnosing occult scaphoid fractures if performed within 72 hours


Computed tomography (CT) scan: best at evaluating fracture characteristics and amount of displacement; less effective at diagnosing occult fractures compared with MRI and bone scan


e. Classification


Location: waist (most common), tubercle, distal pole, proximal pole



Pediatric scaphoid fractures most commonly in distal third because distal pole ossifies before proximal pole, although recent data suggest they occur at other locations as well.


Stability: stable (transverse) versus unstable (oblique, comminuted or displaced)


f. Treatment


Nonoperative



Only nondisplaced scaphoid waist, tubercle, or distal plate fractures should be treated conservatively (not proximal pole).


♦ Thumb spica cast immobilization indicated for nondisplaced fractures. (One study has suggested that the thumb does not need to be included in conservative management of nondisplaced waist fractures.)


♦ Longer duration of casting the more proximal the fracture; distal waist for 3 months, mid-waist for 4 months, proximal third for 5 months


♦ No proven added benefit of short-arm versus long-arm casting


Operative


♦ Indications: > 1 mm displacement, intrascaphoid angle > 35 degrees, unstable vertical or oblique fractures, associated scaphoid fractures with perilunate dislocation, proximal pole fractures, high-demand occupations/sports


♦ Percutaneous fixation performed for minimally displaced scaphoid fractures


▪ Percutaneous fixation: entails an increased risk of screw prominence of subchondral bone compared with open approach


▪ Percutaneous fixation of nondisplaced waist fractures: decreases the time to union and allows early return to work or sports; cost similar to that of casting


♦ Open reduction and internal fixation


▪ Optimal fixation obtained with long central screw placement



Centrally placed screw is biomechanically strongest


▪ Proximal pole scaphoid fracture best treated with dorsal headless compression screw


▪ Nonunion of proximal pole treated with vascularized bone graft ± intraosseous headless screw



Vascularized graft indicated for proximal pole nonunion or nonunion after previously grafted fracture


▪ Nonunion of waist treated with corticocancellous graft or cancellous graft with headless screw


g. Complications


Avascular necrosis: increased incidence with proximal fracture


Nonunion: delay in treatment > 28 days greatly increases risk of nonunion; may lead to development of scaphoid nonunion advanced collapse (see Posttraumatic entries in the Arthritis section, below)



Time to treatment > 1 month increases risk of nonunion.


• Pisiform fracture: uncommon; treat with cast immobilization; if painful nonunion occurs, then excise


• Hook of hamate fracture


a. Mechanism: blunt trauma to palm; commonly seen in baseball, hockey, racquet sports


b. Presentation: pain over hook of hamate; may cause ulnar nerve compression or flexor tendon irritation


c. Imaging: carpal tunnel view or CT scan (note: bipartite hamate has smooth cortical borders)


d. Treatment: cast immobilization for 4–6 weeks; failure of union with persistent pain is treated with excision of fragment


3. Carpal instability


• Dorsal intercalated segmental instability (DISI): lunate extension


a. Mechanism: fall on hyperextended and ulnar deviated wrist


b. Biomechanics: force transmission through scaphoid fossa greater in wrist extension than neutral; force transmission through lunate fossa greater in neutral than extension


c. Caused by scapholunate rupture; dorsal scapholunate ligament is stronger than volar


d. Leads to scaphoid hyperflexion and lunate hyperextension


e. Presentation


Snuffbox tenderness, dorsal wrist pain, decreased grip strength


Watson test: pain or a clunk with pressure applied to volar scaphoid tubercle and wrist brought from ulnar to radial deviation; compare with contralateral side


f. Imaging: AP X-ray: scapholunate gap > 3 mm with clenched fist view (Terry Thomas sign), cortical ring sign; lateral X-ray: scapholunate angle > 60 degrees


g. Arthroscopy: gold standard for diagnosis


h. Treatment: scapholunate ligament repair (early) or reconstruction (late)


• VISI: lunate flexion


a. Mechanism: fall on hyperextended and radial deviated wrist


b. Caused by lunotriquetral rupture; volar lunotriquetral ligament stronger than dorsal


c. Imaging: lateral X-ray: decreased scapholunate angle (< 30 degrees)


d. Treatment: closed reduction and percutaneous pinning (CRPP) or ligament repair in acute setting; chronic instability treated with lunotriquetral (LT) fusion


• Perilunate dislocation


a. Mechanism: high energy, fall on extended arm, ulnar deviated wrist


b. Presentation: swelling, ecchymosis and painful wrist; acute carpal tunnel syndrome in 25% secondary to volar dislocation of lunate; commonly missed diagnosis; frequently also with scaphoid fracture


c. Imaging: PA X-ray: break in Gilula’s lines, overlapping carpal bones; lateral X-ray: dislocation of lunate or midcarpal joint


Jun 28, 2018 | Posted by in ORTHOPEDIC | Comments Off on Hand and Microvasculature
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