Chapter 4 – Hand

Chapter 4 Hand

Yvonne C. Chow and Amanda Akin

Illustrations by Yvonne Chow


  • Injuries to hand and digits common

  • Estimated 5–30 percent of ED injuries1, 2

  • Up to 18 percent of all fractures

  • Up to 9 percent of all sports-related injuries

  • 1.7:1 male-to-female ratio3

  • 60 percent injuries between 16–32 years of age3

  • Typical mechanisms of injury include fall on outstretched hand or direct blow

  • Mortality exceedingly rare

  • Morbidity major concern; severe or poorly managed injuries may affect long-term function of hand and wrist

    • Digit laceration accounts for third most common reason for lost workdays in United States (following back and leg strain)4, 5

Anatomical Considerations/Pathophysiology

  • Dorsal (extensor) surface

  • Volar (flexor) surface

  • Radial (lateral) border

  • Ulnar (medial) border

  • Five metacarpal bones (Figure 4.1)

    • Second and third metacarpal bones are relatively immobile

    • Intrinsic movements of the hand are dependent on stability of the above.6

  • Thumb consists of proximal and distal phalanges, with two sesamoids at metacarpophalangeal (MCP) joint.

  • Fingers consist of proximal, middle, and distal phalanges.

  • Metacarpal and proximal phalanx articulate at MCP joint.

  • Proximal and middle phalanges articulate at proximal interphalangeal (PIP) joint.

  • Middle and distal phalanges articulate at distal interphalangeal (DIP) joint.

  • Thumb only has single interphalangeal (IP) joint.

  • Pediatric physes located at base of all phalanges and first metacarpal, and at heads of second to fifth metacarpals (Figure 4.2).

  • Nine finger flexor tendons (Figure 4.3).

    • Four superficial flexors attach to middle phalanx of fingers – flex PIP

    • Five deep flexors pass through split in superficial tendons to attach to distal phalanx of thumb and fingers – flex DIP

    • Anchored by annular ligaments (“pulleys”) to prevent bowstringing

    • Course through flexor tendon sheaths

  • Extensor tendons (Figure 4.4)

    • Common extensor tendon attaches to middle phalanx via central slip – extends PIP.

    • Lateral extensor bands form terminal extensor tendon, which attaches to distal phalanx – extends DIP.

    • Course through extensor expansion complex (extensor hood).

  • Joint capsule of IP and MCP joints thickened at volar aspect to form dense fibrous structure called volar plate.7

  • Digit collateral ligaments provide medial/lateral stability.

    • Maximally lengthened when digit flexed at 70° at MCP, 30° at PIP, 15° at DIP.8

    • Immobilization should occur at above angles to prevent contractures.9

  • The hand is innervated by the median, radial, and ulnar nerves

  • Median nerve

    • Motor to thumb abduction, flexion, opposition

    • Sensation to volar hand from thumb to radial (lateral) half of ring finger (including dorsal tips) (Figure 4.5A)

  • Radial nerve

    • Motor to thumb extension/abduction, MCP extension, and wrist extension

    • Sensation to dorsal hand from thumb to radial (lateral) half of ring finger (excluding dorsal tips) (Figure 4.5B)

  • Ulnar nerve

    • Motor to thumb adduction, little finger abduction, finger adduction/abduction

    • Sensation to dorsal and volar hand from little finger to ulnar half of ring finger (Figure 4.5c)

  • Vascular supply from radial and ulnar arteries

  • Lymphatic and venous drainage located on dorsum of hand6

Figure 4.1. Bony anatomy of hand.

Figure 4.2. Locations of pediatric growth plates. Note the physis of the first metacarpal is located at the metacarpal base, rather than at the metacarpal head as in the rest of the metacarpals.

Figure 4.3 Flexor tendon anatomy.

Figure 4.4. Extensor tendon complex anatomy.

Figure 4.5a. Sensory distribution of median nerve.

Figure 4.5b. Sensory distribution of radial nerve.

Figure 4.5c. Sensory distribution of ulnar nerve.

Focused History and Physical Exam

  • Important history elements:

    • Hand dominance

    • Sport, position, or occupation

    • Mechanism of injury

    • Position of hand during injury

    • Prior hand injury or surgery

  • General physical exam elements:

  • Inspection

    • Soft tissue swelling

    • Obvious gross deformity (mallet finger, boutonnière)

    • Finger posture

    • Muscle wasting

    • Skin discoloration

    • Wounds

    • Nail avulsion or hematoma

    • Compare with contralateral side

  • Palpation

    • Point of maximal tenderness

    • Bony crepitus

    • Nodules along flexor tendon

  • Range of motion (ROM)

    • Full extension of digits

    • Full flexion of digits into clenched fist

      • Phalanges should be parallel and pointing towards scaphoid bone, with all nails positioned in same plane (Figure 4.6A and Figure 4.6B).

  • Special tests

    • Collateral ligament testing:

      • Hold phalanx proximal and distal to joint being tested, and attempt to open joint by applying both radial and ulnar stress (Figure 4.7A).

      • Stabilize first metacarpal and apply radial stress to proximal phalanx of thumb (Figure 4.7B).

      • Test at 0° and 30° (point of maximal tautness)

    • Test tendon function against resistance

      • Full ROM preserved with 90 percent laceration if no resistance.6, 10

      • Pain along tendon during resistance testing suggests partial laceration10

    • Deep flexor tendon: flex DIP with PIP/MCP held in extension (Figure 4.8)

    • Superficial flexor tendon: flex PIP with other digits held in extension (Figure 4.9)

  • Neurovascular (NV) exam

    • Palpate regional pulses and assess capillary refill.

    • Doppler useful for assessing digital arteries

    • Test sensory using two-point discrimination with paperclip ends 5 mm apart.

    • Median nerve

      • Touch tip of thumb to tip of index finger (“OK” sign) and resist pulling through the ring (Figure 4.10A)

      • Touch tip of thumb to tip of little finger and resist pulling apart (Figure 4.10B)

      • Test sensation over eponychium of index and middle fingers (Figure 4.10C)

    • Radial nerve

      • Extend wrist and digits at MCP against resistance (Figure 4.11A)

      • Test sensation at dorsum of thumb web space (Figure 4.11B)

    • Ulnar nerve

      • Spread fingers against resistance (Figure 4.12A)

      • Push fingers together against resistance

      • Test sensation over little finger tip (Figure 4.12B)

Figure 4.6A. Normal alignment of digits pointing to scaphoid.

Figure 4.6B. Malrotation causing misaligned digit.

Figure 4.7A. Collateral ligament testing of the PIP joint.

Figure 4.7B. Ulnar collateral ligament testing of the thumb.

Figure 4.8. Test deep flexor tendon function by isolating DIP flexion.

Figure 4.9. Test superficial flexor tendon function by isolating PIP flexion of each digit individually.

Figures 4.10A and B. Median nerve motor testing.

Figures 4.10C Median nerve sensory testing.

Figures 4.11A and B. Radial nerve (A) motor and (B) sensory testing.

Figures 4.12A and B. Ulnar nerve (A) motor and (B) sensory testing.

Table 4.1 Key Anatomic Structures and Associated Functions

Structure Function Notes
Flexor digitorum profundus tendon DIP flexion Disruption causes Jersey finger Ulnar innervation
Flexor digitorum superficialis tendon PIP flexion Median innervation
Terminal extensor tendon DIP extension Disruption cases mallet finger Radial innervation
Central extensor slip PIP extension Disruption causes boutonnière deformity Radial innervation
Volar plate Prevents IP hyperextension Associated with dorsal dislocations
Collateral ligaments Provide medial and lateral stability at MCP and IP joints Radial collateral ligament commonly injured in finger dislocations 1st MCP ulnar collateral ligament injured in Skier’s/Gamekeeper’s thumb
Lumbrical muscles MCP flexion 2nd and 3rd – ulnar innervation 4th and 5th – median innervation
Interosseous muscles Finger abduction and adduction Ulnar innervation
Thenar eminence (muscle bellies of abductor pollicis brevis, flexor pollicis brevis, opponens pollicis) Thumb flexion, opposition Atrophy suggests median nerve injury
Hypothenar eminence (muscle bellies of abductor digiti minimi, flexor digiti minimi brevis, opponens digiti minimi) Little finger abduction, MCP flexion, and opposition Atrophy suggests ulnar nerve injury

Differential Diagnosis-Emergent and Common Diagnoses

Table 4.2 Emergent and Common Diagnoses in the Emergency Department

Emergent Diagnoses Common Diagnoses
Severe crush injury Finger sprain
Vascular injury with signs of ischemia or compromise Finger dislocation
High pressure injection injury Collateral ligament rupture (gamekeeper’s thumb)
Flexor tenosynovitis Volar plate injury
Compartment syndrome Phalanx fracture
Jersey finger
Mallet finger
Central slip rupture (boutonniere deformity)
Metacarpal fracture
Boxer’s knuckle
Fight bite
Tendon laceration
Trigger finger
Subungal hematoma
Nailbed laceration

Acute Tendon and Ligament Injuries

Jersey finger

General Description

  • Avulsion injury of flexor digitorum profundus (Figure 4.13)

  • May include bony avulsion.

Figure 4.13. Flexor digitorum profundus rupture in jersey finger injury.


  • Forceful extension of flexed DIP joint

  • Commonly occurs when athlete grabs opponent’s jersey


  • Pain and swelling at the DIP

Physical Exam

  • Unable to actively flex isolated DIP on exam

  • Volar tenderness at DIP and palm (due to retracted tendon)

Essential Diagnostics

  • Digit x-rays to include AP, lateral, and oblique views.

  • X-ray may show avulsion fracture at volar base of distal phalanx.

ED Treatment

  • Dorsal splint is placed with slight flexion of MCP and IP joints.

  • Urgent orthopedic referral for surgical repair 11, 12


  • Discharge

  • Orthopedic referral in 1–2 days for surgical repair

  • Return to sports requires clearance following surgical repair.

    • Early return in mitten-type splint/cast possible for sports with no grasping motion11

    • Full return with grasping motion usually takes four to six months11


  • Loss of deep flexor function if unrepaired or treatment delayed

Pediatric Considerations

  • None

Pearls and Pitfalls

  • Poor outcome if repair delayed more than seven days12

Central Slip Rupture

General Description

  • Avulsion injury of central extensor slip (Figure 4.14)

Figure 4.14. Schematic of a boutonnière deformity following central extensor slip rupture.


  • Deep contusion to PIP

  • Forceful flexion of extended PIP

  • Volar dislocation of PIP


  • Pain and swelling at PIP

Physical Exam

  • Dorsal tenderness at PIP

  • Weak active extension of PIP

  • Classic boutonnière deformity (flexion deformity of PIP with hyperextension of DIP) rarely seen in acute setting13

Essential Diagnostics

  • Digit x-rays to include AP, lateral, and oblique views.

  • X-ray may show avulsion fracture at dorsal base of middle phalanx.

  • Ultrasound may be useful for diagnosis.

ED Treatment

  • Splint PIP joint in complete extension for four to six weeks

  • Leave DIP free


  • Discharge

  • Orthopedic consultation immediately if irreducible PIP dislocation or in two to three days if large, displaced, intra-articular fracture at base of middle phalanx10, 13

  • Return to sports dependent on athlete’s ability to participate with PIP immobilized in extension.


  • May cause boutonnière deformity if left untreated

Pediatric Considerations

  • None

Pearls and Pitfalls

  • Treat injured PIP joint with weak extension and dorsal tenderness empirically as central slip rupture, even without boutonnière deformity.13

Mallet finger

General Description

  • Terminal extensor tendon injury with associated loss of extensor function of the DIP

  • May occur as intra-articular avulsion fracture (Figure 4.15A) or as isolated tendon rupture (Figure 4.15B).

Figures 4.15 A and B. Mallet finger injury (A) with and (B) without avulsion fracture of distal phalanx.


  • Forced flexion of distal phalanx with finger in extension


  • Loss of DIP extension

Physical Exam

  • Distal phalanx in partially flexed position at rest

  • Swelling and tenderness over dorsal aspect of digit

  • Unable to actively extend DIP

Essential Diagnostics

  • Digit x-rays to include AP, lateral, and oblique views.

ED Treatment

  • If nondisplaced fracture or isolated tendon injury, splint with DIP in extension continuously for six to eight weeks14, 15

  • Leave PIP free


  • Discharge

  • Orthopedic consultation in one week if associated avulsion fracture displaced more than 50 percent of articular surface or volar subluxation – may need ORIF.

  • Recommend follow-up visits at two week intervals to monitor compliance with continuous splint.

    • Patient compliance most important factor in success of nonoperative management15

  • Return to sports dependent on athlete’s ability to participate while DIP is splinted in full extension.

  • Consider extension splinting during sports for additional eight weeks after continuous splinting has been completed.16


  • If improperly treated patient will develop swan-neck deformity – flexion of DIP with hyperextension of PIP.

Pediatric Considerations

  • Salter–Harris type II fracture mimics mallet finger or DIP joint dislocation on exam, even though this is an extra-articular fracture.16, 17

  • Splint in slight DIP hyperextension for up to six weeks.16

  • Require close follow-up with weekly x-rays for two weeks to ensure alignment is stable.17

  • Pediatric hand surgeon referral if open or irreducible fracture.

Pearls and Pitfalls

  • DIP must remain in strict extension for six to ten weeks for proper healing.

  • Patient should be shown how to change splint while keeping DIP extended against a hard surface.

  • Any flexion that occurs at DIP requires starting treatment over at day one.17

  • Extension lag may persist following treatment, but usually does not lead to functional deficit.16

Boxer’s knuckle

General Description

  • Rupture of sagittal band on radial aspect of the extensor hood.6, 18


  • Traumatic blow to MCP


  • Pain and swelling over dorsal MCP joint

Physical Exam

  • Ulnar subluxation of extensor tendon during MCP flexion

  • Patient unable to actively extend MCP joint

  • Painful relocation of extensor tendon with passive MCP extension

Essential Diagnostics

  • Hand/digit x-rays to include AP, lateral, and oblique views

ED Treatment

  • Passively extend to relocate tendon.

  • Splint placed with MCP in extension.

  • If punctures wounds/fight bites are present:

    • Prescribe antibiotics to cover oral flora, update tetanus.

    • Do not primarily close wounds

    • Irrigate wounds copiously prior to any splint placement.


  • Discharge

  • Hand surgeon follow-up in one week

  • May return to sports with MCP splinted in extension, as limited by pain


  • Deep space infection may occur with fight bites (see “Fight bite” for further details)

Pediatric Considerations

  • None

Pearls and Pitfalls

  • None

Tendon Laceration

General Description

  • Injury to flexor or extensor tendons

  • May be open or closed

  • May be partial or complete

  • See “Jersey finger,” “Central slip rupture,” and “Mallet finger” for injuries to specific tendons


  • Most commonly caused by sharp object lacerating skin and underlying tendon.

  • Direct blunt force

  • Opposing force to tendon during contraction


  • Pain and swelling to affected area

  • May have acute deformity

Physical Exam

  • Skin wound may be present

  • Determine position of hand when injury occurred

    • Inspect visible tendon during full digit ROM

    • Injured area of tendon may be retracted proximal to, or extend distally past, skin wound.

  • Must isolate each digit and joint for appropriate testing.

  • Test active ROM

  • Test strength against resistance

    • Full motion may be preserved with only 10 percent tendon intact6, 10

    • Pain along tendon during resistance testing suggests partial laceration10

Essential Diagnostics

  • Hand/digit x-rays to include AP, lateral, and oblique views

ED Treatment

  • Irrigate wound if contaminated.

  • No definitive recommendations for treatment of partial lacerations:6, 19

    • Consult with orthopedics regarding appropriate follow-up

    • Partial flexor lacerations: apply dorsal splint in position of function for three to four weeks

    • Partial extensor lacerations: apply splint with MCP in full extension (to reduce tension on tendon) for three to four weeks

  • Complete flexor tendon lacerations:

    • Require urgent hand surgeon consultation, preferably within twelve to twenty-four hours.6

    • Avoid excessive manipulation of transected tendon (promotes adhesions)6

    • Apply dorsal splint in position of function.

  • Complete extensor tendon lacerations

    • If located over proximal phalanx or dorsum of hand, may be repaired by experienced ED physician using figure-of-eight or horizontal mattress sutures.6, 10, 20

    • Otherwise refer to hand surgeon for immediate primary or delayed primary (within one week) repair.6, 20

    • Lacerations resulting from fight bites should have delayed repair following course of antibiotics; may need IV antibiotics and intraoperative washout.


  • Discharge

  • Urgent orthopedic referral within one day for complete flexor lacerations6; within one to two days for complete extensor lacerations.6, 20

  • Orthopedic referral in one week for partial lacerations.

  • May be reasonable to return to play as soon as one to two weeks for partial lacerations, may be limited by ability to participate while wearing protective splint.

  • Return to sports requires clearance following surgical repair

    • Full return to play with normal strength and ROM may take several months


  • Loss of flexion or extension function

  • Entrapment and triggering of finger from partial flexor tendon rupture

Pediatric Considerations

  • Urgent referral within twenty-four hours to pediatric hand surgeon recommended for all flexor and extensor tendon injuries.10

Pearls and Pitfalls

  • Closed injuries may be easily missed and untreated, resulting in chronic deformities.

  • Open injuries may be missed if tendon not inspected during full digit ROM.

Skier’s/Gamekeeper’s Thumb

General description

  • Sprain or rupture of ulnar collateral ligament (UCL) of thumb (Figure 4.16)

Figure 4.16. Rupture of the ulnar collateral of the thumb.


  • Forced abduction of thumb at MCP joint


  • Pain and swelling over ulnar aspect of thumb MCP

Physical Exam

  • Tenderness over ulnar aspect of thumb MCP

  • Unable to resist adduction stress to thumb (Figure 4.7b)

    • Lack of endpoint on stress testing indicates complete rupture

  • Weakness with pinching

Essential Diagnostics

  • Obtain x-rays prior to stress testing

  • Thumb x-rays to include AP, lateral, and oblique views

  • “Sag sign” caused by volar subluxation of proximal phalanx suggests UCL injury

ED Treatment

  • Thumb spica splint21

  • Urgent referral to orthopedics if complete rupture or associated fracture


  • Discharge

  • Orthopedic referral in two to three days for surgical repair if complete rupture or associated fracture, otherwise follow-up in one week.10, 21

  • Partial tears with limited laxity may be treated with thumb spica cast for four to six weeks.

  • Return to sports dependent on severity of injury and athlete’s ability to participate with protective thumb spica splint in place.

  • Full return to sports without splint once ROM and strength have returned to normal, usually six to eight weeks for nonoperative cases and twelve weeks for operative treatment.21


  • Long-term instability will result in difficulty with pinching motion.

Pediatric Considerations

  • Prompt pediatric hand surgeon referral in one to two days for ORIF if avulsion fracture at insertion of UCL present.22

Pearls and Pitfalls

  • Base of adductor pollicis aponeurosis may interpose between ends of UCL in complete rupture (Stener lesion) and inhibit healing; will require surgical repair.

Volar Plate Rupture

General Description

  • Injury to volar plate at MCP, PIP, or DIP joint

  • Most commonly at PIP


  • Hyperextension of joint

  • Dorsal dislocation


  • Pain and swelling at the affected joint

Physical Exam

  • Tenderness at volar aspect of affected joint

  • Test collateral ligaments for concomitant injury (Figure 4.7A)

  • Unstable injury if joint able to be hyperextended or dorsally subluxed with passive ROM.

  • Joint may be “locked” in extension if volar plate becomes caught between articular surfaces.

Essential Diagnostics

  • Digit x-rays to include AP, lateral, and oblique views.

  • X-ray may show avulsion fracture at volar base of middle phalanx.

ED Treatment

  • If stable: buddy tape alone to prevent hyperextension, or dorsal block splint with PIP at 30° flexion for one to two weeks followed by buddy tape and early ROM.23, 24

  • If unstable but reducible: dorsal block splint as above for four weeks with weekly decreases in amount of flexion to reach full extension over one month.23, 24

  • If irreducible: emergent consultation with hand surgeon.


  • Discharge

  • Immediate orthopedic consultation from ED if irreducible

  • Orthopedic referral in two to three days if unstable or intra-articular avulsion fracture fragment – may require operative treatment10

  • Stable injuries treated with dorsal block splint should have weekly follow-up to gradually decrease amount of flexion in splint until full extension is reached.

  • Return to sports dependent on athlete’s ability to participate with dorsal block splint or buddy tape in place.23


  • May cause swan-neck deformity (hyperextension of PIP and flexion of DIP) if untreated

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Sep 1, 2020 | Posted by in SPORT MEDICINE | Comments Off on Chapter 4 – Hand
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