Background/Epidemiology
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
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).
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.
Mechanism
Forceful extension of flexed DIP joint
Commonly occurs when athlete grabs opponent’s jersey
Presentation
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
Disposition
Complications
Loss of deep flexor function if unrepaired or treatment delayed
Pediatric Considerations
None
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.
Mechanism
Deep contusion to PIP
Forceful flexion of extended PIP
Volar dislocation of PIP
Presentation
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
Disposition
Complications
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.
Mechanism
Forced flexion of distal phalanx with finger in extension
Presentation
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
Disposition
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
Complications
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
Mechanism
Traumatic blow to MCP
Presentation
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.
Disposition
Discharge
Hand surgeon follow-up in one week
May return to sports with MCP splinted in extension, as limited by pain
Complications
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
Mechanism
Most commonly caused by sharp object lacerating skin and underlying tendon.
Direct blunt force
Opposing force to tendon during contraction
Presentation
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
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.
Disposition
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
Complications
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.
Mechanism
Forced abduction of thumb at MCP joint
Presentation
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
Disposition
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
Complications
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
Mechanism
Hyperextension of joint
Dorsal dislocation
Presentation
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.
Disposition
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
Complications
May cause swan-neck deformity (hyperextension of PIP and flexion of DIP) if untreated
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