9 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. Fig. 9.1 The radius and ulna of the right arm in (a) supination and (b) pronation. (From Schuenke M, Schulte E. General Anatomy and the Musculoskeletal System: Thieme Atlas of Anatomy. New York: Thieme; 2005. Illustration by Karl Wesker.) Fig. 9.2 The radius and ulna of the right forearm. Anterosuperior view. The proximal and distal radioulnar joints are functionally interlinked by the interosseous membrane between the radius and ulna. (From Schuenke M, Schulte E. General Anatomy and the Musculoskeletal System: Thieme Atlas of Anatomy. New York: Thieme; 2005. Illustration by Karl Wesker.) Fig. 9.3 Cross section through the right proximal radioulnar joint in pronation. Owing to the slightly oval shape of the radial head, the pronation/supination axis that runs through the radial head moves ~ 2 mm radially during pronation. This ensures that when the hand is pronated, there will be sufficient space for the radial tuberosity. (From Schuenke M, Schulte E. General Anatomy and the Musculoskeletal System: Thieme Atlas of Anatomy. New York: Thieme; 2005. Illustration by Karl Wesker.) • 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. Fig. 9.4 Rotation of the radius and ulna during (a) supination, (b) semipronation, and (c) pronation. The dorsal and palmar radioulnar ligaments are part of the “ulnocarpal complex,” which serves to stabilize the distal radioulnar joint. The mode of contact between the two distal articular segments varies with the position of the radius and ulna. (From Schuenke M, Schulte E. General Anatomy and the Musculoskeletal System: Thieme Atlas of Anatomy. New York: Thieme; 2005. Illustration by Karl Wesker.) Fig. 9.5 Range and axis of pronation/supination of the right hand. The neutral (0-degree) position of the hand and forearm is called semipronation. The axis of pronation/supination extends through the head of the radius and the styloid process of ulna. (a) Supination. (b) Pronation. (c) Supination of the hand with the elbow flexed. (d) Pronation of the hand with the elbow flexed. (From Schuenke M, Schulte E. General Anatomy and the Musculoskeletal System: Thieme Atlas of Anatomy. New York: Thieme; 2005. Illustration by Karl Wesker.) 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 Fig. 9.6 The distal articular surfaces of the radius and ulnar of right forearm. (From Schuenke M, Schulte E. General Anatomy and the Musculoskeletal System: Thieme Atlas of Anatomy. New York: Thieme; 2005. Illustration by Karl Wesker.) Fig. 9.7 The bones of the right hand. Palmar view. (From Schuenke M, Schulte E. General Anatomy and the Musculoskeletal System: Thieme Atlas of Anatomy. New York: Thieme; 2005. Illustration by Karl Wesker.) Fig. 9.8 The bones of the right hand. Dorsal view. The radiocarpal and mid carpaljoints are indicated by green and blue lines respectively. (From Schuenke M, Schulte E. General Anatomy and the Musculoskeletal System: Thieme Atlas of Anatomy. New York: Thieme; 2005. Illustration by Karl Wesker.) Fig. 9.9 Movement of the radiocarpal and midcarpal joints. Starting from the neutral (0-degree) position: (a) palmar flexion and dorsal extension are performed about the transverse axis, while (b) radial and ulnar deviation occur about a dorsopalmar axis. The transverse axis runs through the lunate for the radiocarpal joint and through the capitate for the midcarpal joint. The dorsopalmar axis runs through the capitates bone. Thus, although palmar flexion and dorsal extension can occur in both the radiocarpal and midcarpal joints, radial and ulnar deviation occurs in the radiocarpal joint. (From Schuenke M, Schulte E. General Anatomy and the Musculoskeletal System: Thieme Atlas of Anatomy. New York: Thieme; 2005. Illustration by Karl Wesker.) 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 Fig. 9.10 Carpal ossification. Eight bones that ossify in characteristic counterclockwise order (when looking at volar aspect of right wrist) beginning with the hamate and ending with the pisiform. ◦ 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 Fig. 9.11 Functional position of the hand. For postoperative immobilization of the hand, the desired position of the wrist and fingers should be considered when the cast, splint, or other device is applied. Otherwise the ligaments may shorten and the hand can no longer assume a resting position. (From Schuenke M, Schulte E. General Anatomy and the Musculoskeletal System: Thieme Atlas of Anatomy. New York: Thieme; 2005. Illustration by Karl Wesker.) Fig. 9.12 The ligaments of the right hand. Posterior view. The various ligaments in the carpal region form a dense network that strengthens the joint capsule of the wrist. Four groups of ligaments can be distinguished based on their location and arrangement ((From Schuenke M, Schulte E. General Anatomy and the Musculoskeletal System: Thieme Atlas of Anatomy. New York: Thieme; 2005. Illustration by Karl Wesker.) Fig. 9.13 The ligaments of the right hand. Anterior view. Among the ligaments that bind the carpal bones together (intercarpal ligaments), a distinction is made between internal ligamentsandsurfaceligaments. The internal ligaments interconnect the individual bones ata deeper level and include the interosseous intercarpal ligaments (notshown here). The surface ligaments consist of the dorsal (see A) andpalmar intercarpal ligaments. (From Schuenke M, Schulte E. General Anatomy and the Musculoskeletal System: Thieme Atlas of Anatomy. New York: Thieme; 2005. Illustration by Karl Wesker.) Fig. 9.14 Range of motion of the finger joints. (a) Flexion in the distal interphalangeal (DIP) joint. (b) Flexion in the proximal interphalangeal (PIP) joint. (c) Flexion in the metacarpophalangeal (MCP) joint. (d) Extension in the distal interphalangeal (DIP) joint. (e) Extension in the metacarpophalangeal (MCP) joint. (f) Abduction and adduction in the MCP joint. (From Schuenke M, Schulte E. General Anatomy and the Musculoskeletal System: Thieme Atlas of Anatomy. New York: Thieme; 2005. Illustration by Karl Wesker.) 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 Fig. 9.15 Extensor compartments. Dorsal view. There are total of six compartments, numbered 1 to 6, from the radial to the ulnar side of the wrist. (From Schuenke M, Schulte E. General Anatomy and the Musculoskeletal System: Thieme Atlas of Anatomy. New York: Thieme; 2005. Illustration by Karl Wesker.) Fig. 9.16 Axial view of the distal radioulnar joint and extensor compartments of the wrist. There are six fibro-osseus tunnels created by the extensor retinaculum and intervening septa that divide the extensor tendons. Note Lister’s tubercle redirects the extensor pollicis longus to the thumb. (Modified from Schuenke M, Schulte E. General Anatomy and the Musculoskeletal System: Thieme Atlas of Anatomy. New York: Thieme; 2005. Illustration by Karl Wesker.) • 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 Fig. 9.17 Flexor tendon zones of the hand. Zones of the hand are used to help guide flexor tendon injury and repair. Zone I is distal to the flexor digitorum superficialis (FDS) insertion. Zone II is between the distal palmar crease and FDS insertion. Zone III is mid-palm. Zone IV is the carpal tunnel. Zone V is the distal forearm. 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 Fig. 9.18 Vascular supply to the flexor tendons. Flexor tendons are supplied within their sheath by branches of the palmar digital arteries via the vincula longa and brevia. Note the flexor digitorum profundus (FDP) traveling through Camper’s chiasm to insert on the distal phalanx. (From Schuenke M, Schulte E. General Anatomy and the Musculoskeletal System: Thieme Atlas of Anatomy. New York: Thieme; 2005. Illustration by Karl Wesker.) Fig. 9.19 Sensory innervations of palm of the hand. (From Schuenke M, Schulte E. General Anatomy and the Musculoskeletal System: Thieme Atlas of Anatomy. New York: Thieme; 2005. Illustration by Karl Wesker.) ♦ 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 Fig. 9.20 Sensory innervations of dorsum of the hand. (From Schuenke M, Schulte E. General Anatomy and the Musculoskeletal System: Thieme Atlas of Anatomy. New York: Thieme; 2005. Illustration by Karl Wesker.) Fig. 9.21 Sensory innervations of (a) anterior and (b) posterior arm and forearm. (From Schuenke M, Schulte E. General Anatomy and the Musculoskeletal System: Thieme Atlas of Anatomy. New York: Thieme; 2005. Illustration by Karl Wesker.) Fig. 9.22 Course of the median nerve. The median nerve is composed of the medial and lateral cords of the brachial plexus. The median nerve runs in the medial bicipital groove and then passes under the bicipital aponeurosis and between the two heads of the pronator teres to the forearm. After giving off the anterior interosseus nerve distal to the pronator teres, the median nerve runs between the flexor digitorum superficialis and the profundus to the wrist. The medial nerve then passes through the carpal tunnel and gives off its terminal branches. (From Schuenke M, Schulte E. General Anatomy and the Musculoskeletal System: Thieme Atlas of Anatomy. New York: Thieme; 2005. Illustration by Karl Wesker.) Fig. 9.23 View into the carpal tunnel. Median nerve travels through the carpal tunnel between the flexor digitorum superficialis (FDS) and the flexor pollicis longus (FPL). The recurrent motor branch of the median nerve has a variable course being extraligamentous 50%, subligamentous 30%, and transligamentous 20%. (From Schuenke M, Schulte E. General Anatomy and the Musculoskeletal System: Thieme Atlas of Anatomy. New York: Thieme; 2005. Illustration by Karl Wesker.) • 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 Fig. 9.24 Course of the ulnar nerve. The ulnar nerve is a continuation of the medial cord of the brachial plexus. The ulnar nerve pierces the medial intermuscular septum halfway down the arm. It reaches the elbow joint between the septum and the medial head of the triceps and crosses over the joint just distal to the medial epicondyle. The ulnar nerve then travels between the two heads of the flexor carpi ulnaris (FCU) and then travels beneath the FCU to the wrist. The nerve enters the hand through the ulnar tunnel, where it divides into its superficial sensory and deep motor branch. (From Schuenke M, Schulte E. General Anatomy and the Musculoskeletal System: Thieme Atlas of Anatomy. New York: Thieme; 2005. Illustration by Karl Wesker.) Fig. 9.25 Bony landmarks of the ulnar tunnel (Guyon’s canal). The pisiform (ulnar) and the hook of the hamate (distal and radial) provide the bony landmarks that the ulnar artery and nerve travel. The transverse carpal ligament serves as the floor, and the volar carpal ligament the roof of Guyon’s canal. (From Schuenke M, Schulte E. General Anatomy and the Musculoskeletal System: Thieme Atlas of Anatomy. New York: Thieme; 2005. Illustration by Karl Wesker.) Fig. 9.26 Course of radial nerve. The radial nerve is a continuation of the posterior cord of the brachial plexus. The radial nerve travels with the profunda brachii artery posteriorly around the humerus in the radial groove. Approximately 10 cm proximal to the lateral epicondyle the radial nerve pierces the lateral intermuscular septum. The radial nerve then runs distally between the brachioradialis and the brachialis muscle. In the proximal forearm the radial nerve branches into the superficial and deep branch. The deep branch pierces the supinator and continues to the wrist as the posterior interosseus nerve. The superficial branch accompanies the radial artery down the forearm with the brachioradialis muscle. (From Schuenke M, Schulte E. General Anatomy and the Musculoskeletal System: Thieme Atlas of Anatomy. New York: Thieme; 2005. Illustration by Karl Wesker.) ◦ 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) Fig. 9.27 The superficial palmar arch and its branches. The superficial palmar arch is the terminal branch of the ulnar artery. (From Schuenke M, Schulte E. General Anatomy and the Musculoskeletal System: Thieme Atlas of Anatomy. New York: Thieme; 2005. Illustration by Karl Wesker.) • 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 Fig. 9.28 The deep palmar arch and its branches. The deep palmar arch is the terminal branch of the radial artery. (From Schuenke M, Schulte E. General Anatomy and the Musculoskeletal System: Thieme Atlas of Anatomy. New York: Thieme; 2005. Illustration by Karl Wesker.) Fig. 9.29 Arterial anastomoses in the hand. The ulnar and radial artery are connected by the superficial and deep palmar arch, the perforating branches, and the dorsal carpal network. (From Schuenke M, Schulte E. General Anatomy and the Musculoskeletal System: Thieme Atlas of Anatomy. New York: Thieme; 2005. Illustration by Karl Wesker.) ◦ 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 Fig. 9.30 Superficial muscles after removal of a palmar aponeurosis. (From Schuenke M, Schulte E. General Anatomy and the Musculoskeletal System: Thieme Atlas of Anatomy. New York: Thieme; 2005. Illustration by Karl Wesker.) • 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. Fig. 9.31 Muscles of hand. The flexor digitorum superficialis muscle has been removed, and its four tendon insertions have been divided at the level of the metacarpophalangeal joints. The transverse carpal ligament has been partially removed to open the carpal tunnel. (From Schuenke M, Schulte E. General Anatomy and the Musculoskeletal System: Thieme Atlas of Anatomy. New York: Thieme; 2005. Illustration by Karl Wesker.) 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 Fig. 9.32 Muscles of the hand. The flexor digitorum profundus muscle has been removed, and its four tendons of insertion and lumbricals arising from them have been divided. The flexor pollicis longus and flexor digit minimi muscles have also been removed. (From Schuenke M, Schulte E. General Anatomy and the Musculoskeletal System: Thieme Atlas of Anatomy. New York: Thieme; 2005. Illustration by Karl Wesker.) 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. Fig. 9.33 Origins and insertions of the palmar muscles of the hand. Red, origin; blue, insertion. (From Schuenke M, Schulte E. General Anatomy and the Musculoskeletal System: Thieme Atlas of Anatomy. New York: Thieme; 2005. Illustration by Karl Wesker.) ◦ 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) Fig. 9.34 Origins and insertions of the dorsal muscles of the hand. Red, origin; blue, insertion. (From Schuenke M, Schulte E. General Anatomy and the Musculoskeletal System: Thieme Atlas of Anatomy. New York: Thieme; 2005. Illustration by Karl Wesker.) • 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 Fig. 9.35 Anterior muscles of the forearm. (a) The superficial flexors and mobile wad are shown. (b) The mobile wad is removed along with flexor carpi radialis, flexor carpi ulnaris, abductor pollicis longus, palmaris longus, and biceps brachii. (From Schuenke M, Schulte E. General Anatomy and the Musculoskeletal System: Thieme Atlas of Anatomy. New York: Thieme; 2005. Illustration by Karl Wesker.) Fig. 9.36 Anterior muscles of the forearm. (a) Pronator teres and flexor digitorum superficialis have been removed. (b) All the muscles have been removed. Red, origin; blue, insertion. (From Schuenke M, Schulte E. General Anatomy and the Musculoskeletal System: Thieme Atlas of Anatomy. New York: Thieme; 2005. Illustration by Karl Wesker.) ◦ 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. Fig. 9.37 Posterior muscles of the forearm. (a) The superficial extensors and mobile wad are shown. (b) The triceps brachii, anconeus, flexor carpi ulnaris, extensor carpi ulnaris, and extensor digitorum have been removed. (From Schuenke M, Schulte E. General Anatomy and the Musculoskeletal System: Thieme Atlas of Anatomy. New York: Thieme; 2005. Illustration by Karl Wesker.) ◦ 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 Fig. 9.38 Posterior muscles of the forearm. (a) Abductor pollicis longus, extensor pollicis longus, and mobile wad have been removed. (b) All the muscles have been removed. Red, origin; blue, insertion. (From Schuenke M, Schulte E. General Anatomy and the Musculoskeletal System: Thieme Atlas of Anatomy. New York: Thieme; 2005. Illustration by Karl Wesker.) ◦ 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. Fig. 9.39 (a,b) Cross section through the forearm. Note that the forearm is divided into three compartment: anterior, posterior, and the mobile wad (which includes the brachioradialis and the extensor carpi radialis longus and brevis). (From Schuenke M, Schulte E. General Anatomy and the Musculoskeletal System: Thieme Atlas of Anatomy. New York: Thieme; 2005. Illustration by Karl Wesker.) Fig. 9.40 Anterior approach of Henry. Proximally between brachioradialis and pronator teres and distally between flexor carpi radialis and radial artery. (From Schuenke M, Schulte E. General Anatomy and the Musculoskeletal System: Thieme Atlas of Anatomy. New York: Thieme; 2005. Illustration by Karl Wesker.) ♦ 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) Fig. 9.41 Posterior approach to the radius. Provides exposure to the proximal third of the radius and the interval between the extensor carpi radialis brevis (radial nerve) and the extensor digitorum communis (posterior interosseus nerve). Modified from THIEME Atlas of Anatomy, General Anatomy and Musculoskeltal System, © Thieme 2005, Illustration by [Karl Wesker] 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 Fig. 9.42 Dorsal approach to wrist. Interval between the third (extensor pollicis longus) and fourth (extensor digitorum communis) dorsal compartment of the wrist. Indicated for open reduction and internal fixation (ORIF) of the distal radius or carpal fracture, proximal row carpectomy, wrist fusion, posterior interosseous nerve (PIN) neurectomy, or extensor tendon repair or synovectomy. (From Schuenke M, Schulte E. General Anatomy and the Musculoskeletal System: Thieme Atlas of Anatomy. New York: Thieme; 2005. Illustration by Karl Wesker.) 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. Fig. 9.43 Bruner incision. 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 Fig. 9.44 Wrist arthroscopic portals. APL, abductor pollicis longus; ECRB, extensor carpi radialis brevis; ECRL, extensor carpi radialis longus; ECU, extensor carpi ulnaris; EDC, extensor digitorum communis; EDM, extensor digiti minimi; EIP, extensor indicis proprius; EPB, extensor pollicis brevis; EPL, extensor pollicis longus; MCR, midcarpal joint radial; MCU, midcarpal joint ulnar. • 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 ♦ 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 ◦ Mayfield classification: counterclockwise direction of ligament disruption ♦ Stage I: scapholunate ♦ Stage II: scaphocapitate ♦ Stage III: lunotriquetral ♦ Stage IV: lunate dislocation
Hand and Microvasculature
I. Anatomy
II. Trauma
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