Astute Diagnosis of Phalangeal Injuries Can Prevent Lasting Damage

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Phalangeal injuries are extremely common. Though often radiographically unimpressive, the underlying tendinous insertions are critical for grip and hand function. Injuries involving these structures are easily missed in the ED and can lead to functional disability.

Disability resulting from hand injuries can have life-changing implications. A patient’s age, hobbies, vocation and activity level are major determinants of how much functional disability can be tolerated. This can differ from one patient to the next. An accurate assessment of hand dominance, vocation, activity level and potential compliance are essential in determining the appropriate treatment pathway.

ED physicians often minimize fractures of the phalanges, missing ligamentous injuries or fracture patterns that require surgical intervention. In-depth understanding of the varying determinants of treatment is essential when discussing treatment options with hand consultants. Perhaps more importantly, the ability to communicate expectations and outcomes is equally valuable when educating patients.


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Mechanism
Axial load, hyperextension and crush mechanisms are the most common causes of injury to the phalanges. Axial load injuries result from “jamming” the digit into a fixed object. Hyperextension is also common and typically seen in sports injuries. Hyperextension is frequently associated with dislocations or fracture-dislocations. Crush related injuries are typically work-related and have a high incidence of associated soft tissue, neurovascular and musculotendinous injuries. Assessment of the crushed digit requires detailed assessment of viability. By anatomic location, the thumb, second and 5th digits are injured most often.

Anatomy and Deforming Forces
Among the most important anatomic considerations are the opposing flexor and extensor tendons inserting on the distal phalanx. The flexor digitorum profundus inserts on the volar aspect of the distal phalanx and acts as a volar deforming force. The extensor digitorum acts in opposition on the dorsal side and is the primary extensor of the digit. Of the two, FDP applies greater force. The interossei extend at the IP joints but the combined force of the interossei along with extensor digitorum is still outweighed by the flexor digitorum, which is why the resting position of the IP joints is in flexion.

The flexor digitorum superficialis inserts in the middle aspect of the middle phalanx and flexes the proximal interphalangeal joint.


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FingerTipsAThe volar plate, also referred to as the palmar plate, is a thickened fibrous ligament spanning the interphalangeal joints and the MCP joint on the volar (palmar) side of the joint capsule. Its function is to enhance stability of the joint and limit hyperextension. The volar plate is often injured in interphalangeal joint dislocations.

Clinical Evaluation
Because many hand and finger complaints are secondary to crush injuries, associated neuromuscular, soft tissue and musculotendinous injuries are common. Recalling that the proper digital nerves run longitudinally along each side of the digit, a simple test of sensation on the distal ulnar and radial borders of each digit is a reliable indicator of sensory function. Although these nerves are unlikely to be repaired when injured, I find it valuable to inform patients that their injury resulted in nerve damage, and some loss of sensation may be permanent. A failure to address this is seen as a “miss” by patients when, often, the ED doc simply fails to discuss it.

Assessing vascular viability is extremely important in crush injuries or any injury threatening the digit. Capillary refill and color are good determinants, but if there’s any additional concern, a small pinprick with a 27g needle will help. Immediate bright red blood is a good indicator, while no blood is obviously a poor indicator. I find this an important tool in emphasizing urgency to my hand surgery colleagues.

Tendon function should be assessed by evaluating abduction and adduction (interossei), extension of the digits (common extensor tendon) and flexion at the MCP and DIP (flexor digitorum superficialis and profundus, respectively). Be sure to test flexion of the DIPD joints and PIP joints in isolation. For profundus this is done by holding the IP joint to prevent movement, then observing flexion of the DIP joint.  For superficialis this is done by holding the MCP in extension and testing flexion of the IP joint.


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The thumb should be tested independently with focus on the flexors and extensors at the IP and MCP joints. Extensor pollicis longus is tested by extension at the IP and Extensor pollicis brevis by extension at the proximal phalanx and metacarpal. The same joints are tested for flexor pollicis longus and flexor pollicis brevis with respective opposing actions. Opponens pollicis should also be tested by opposing the thumb to the fifth finger and testing resistance.

Open Fractures
Open fractures of the phalanges do not require emergency wash out unless grossly contaminated. The Swanson classification system is a simple binary system that is predictive of clinical outcomes.

  • Type One: Clean, no significant contamination
  • Type Two: Dirty, grossly contaminated

The incidence of infection for each is roughly 1.5% and 15%, respectively. Most hand surgeons tolerate 1-2% but not 15%. ED physicians should not feel as though hand consultants are mismanaging these injuries when opting not to not take the patient emergently for operative washout. Grossly contaminated wounds or those extremely high risk for infection are more likely to benefit from early washout and these factors should be communicated clearly with consultants [1,2,3].

Clinical Pearl
Assume the ED washout is the definitive washout for open fractures. Volume and pressure are the only two independent variables shown to predict decreased incidence of infection, so the more volume, the better.

Treatment of Phalangeal Fractures
Intra-articular Fractures: As mentioned above, any displaced intra-articular fracture should be considered for surgical intervention. Most can be discharged and performed on an outpatient basis, but recognizing and communicating the possibility of surgical intervention will help to coordinate the postoperative treatment plan with both the consultant and the patient. Any visible displacement on X-ray is concerning and certainly more then 2mm of displacement increases the likelihood for surgical intervention in a high-functioning individual.

Middle Phalanx (figure B at the top of the screen): Significantly displaced fractures of the middle phalanx require reduction. The primary deforming force is the flexor digitorum superficialis. One of the two powerful finger flexors, flexor digitorum superficialis inserts in the middle of the volar aspect of the middle phalanx. Accordingly, fractures distal to the insertion will appear to have dorsal angulation due to the strong volar pull of superficialis on the proximal segment. Fractures proximal to the insertion will have volar angulation because the distal fragment is pulled in a volar direction.

Distal Phalanx: Most distal phalangeal injuries are crush-related injuries. Many of these are not amenable to surgical fixation because of the minute size of the fracture fragments. Most are simply treated with splinting and tend to do well. Those with intra-articular involvement will develop some loss of motion as well as traumatic arthritis.

There are two fracture patterns of the distal phalanx, however, that should raise concern for the ED physician. These are dorsal and volar lip fractures at the base of the distal phalanx.

The distal phalanx is the insertion site for extensor digitorum dorsally and for flexor digitorum profundus on the volar side. This seemingly small and often neglected bone is in fact highly complex from a kinesiological standpoint. These powerful deforming forces often result in permanent deformity when associated with injury.

FingerTipsCFractures of the dorsal lip avulse the extensor digitorum, leaving the strong flexor digitorum profundus un-opposed. This results in a flexed DIP joint and ultimately a “Mallet Finger.” Treatment requires a minimum of 6-8 weeks of extension splinting. Some authors suggest early surgical repair. Mallet injuries can also occur when the extensor tendon is avulsed without radiographic evidence of dorsal lip fracture. This usually occurs when “jamming” the distal phalanx into a fixed object. It’s important for emergency physicians to recognize these injuries and to initiate extension splinting immediately. Alumi-foam splints are acceptable from the ED, but will need to be converted to a smaller and more convenient splint on an outpatient basis. (Figure C to the right)

Clinical Pearl: It’s critical for the emergency physician to emphasize that splinting must be maintained 24 hours per day, 7 days per week, without exception, during the initial healing period. Although light range of motion may be initiated prior, it is also important to emphasize the 6-8 week healing process which seems extreme for what patients often perceive as a “minor injury.”

FingerTipsDFractures of the volar lip avulse the insertion of the flexor digitorum profundus leaving the extensor digitorum unopposed. This causes the DIP joint to remain in a fixed extended position and the patient is unable to flex at the DIP joint. This injury can also be a pure tendon avulsion without radiographic evidence of volar lip fracture. The resulting deformity is referred to as a “jersey finger” because the
injury often occurs when football and rugby players grab the jersey of another player with the tips of their fingers under massive force, subsequently avulsing the flexor digitorum profundus [4,5]. Like all other flexor tendon injuries in the hand, treatment is always surgical repair. (Figure D to the right)

Thumb Phalangeal Fractures
Thumb phalangeal fractures are classified as either tuft fractures, longitudinal fractures or transverse fractures. Tuft fractures are typically comminuted and associated with soft tissue and nail bed injury. The fracture patterns are rarely amenable to reduction or stabilization. Tuft fractures are treated with 4 weeks of immobilization. Longitudinal fractures, though uncommon, may require pin fixation and the ED doc should be on the watch for this rare and unstable fracture pattern.

As with other distal phalangeal fractures, significantly displaced patterns may also require stabilization particularly in patients with high functional demand of their hand and fingers.

Spiral or oblique fractures present a unique challenge. They are highly prone to displacement and may require surgical fixation due to the highly unstable nature of the fracture pattern itself [4,5].

Dislocations
Dislocation can occur at any joint of the metacarpals and phalanges and may also be associated with fractures. Fracture-dislocations can make reduction extremely difficult. If the ED doctor is unable to reduce a dislocated joint in the presence of associated fracture, operative intervention is likely, and hand surgery should be consulted at the time of the ED visit. Fracture dislocations most commonly result from hyperextension injuries. Intra-articular involvement, which is also common, may require surgery.

A true lateral X-ray is critical in evaluating dislocations. Surprisingly, a large number of dislocations are actually missed by ED physicians because associated soft tissue swelling does not make the deformity obvious and a poor lateral X-ray does not reveal what can sometimes be subtle subluxation.

Although dislocations seem straightforward in the emergency room, the timing of immobilization, limits on early range of motion and need for delayed surgical intervention need to be determined by a hand surgeon. Referral to hand surgery within five days of injury is recommended.

Clinical Pearl: Because most dislocations result from hyperextension, the distal fragment displaces dorsally. This typically causes damage to the volar plate (Figure F, the thickened ligamentous structure on the volar aspect of the joint capsule that resists hyperextension). The volar plate is frequently torn and becomes interposed in the joint space, making reduction difficult or impossible. Hyperextension during reduction can unlock and release the interposed volar plate. When unsuccessful, these injuries frequently require operative intervention.

Nail Bed Injuries
Nail bed injuries often accompany tuft fractures and are frequently neglected. When the nail has been avulsed and an obvious nail bed injury is noted, primary repair should be performed. Chromic gut has long been the accepted suture. The nail must be replaced under the eponychium. The practice is rarely performed by community ED physicians.  Failure to do so results in closure of the eponychium and the new nail arising from the germinal matrix cannot develop appropriately along the surface of the nail bed. Instead, it will turn downward and often interfere with the bone, resulting in deformity. Believe it or not, the seemingly archaic practice of placing part of the suture packaging under the nail and sewing it in place is still recommended.

Clinical Pearl: Recent studies have suggested that nail bed injuries can be acceptably repaired with Dermabond [9].

Controversies In Treatment
The standard treatment of subungual hematomas has gone through radical changes over the past three decades. Originally all subungual hematomas were presumed to have associated nail bed injuries as a cause of the bleeding (a logical presumption). Accordingly, removal of the nail, evacuation of the hematoma, primary repair of the nail-bed injury and replacement of the nail was recommended. In the 1990s, multiple studies demonstrated that simple subungual hematomas, as defined by intact paronychial skin edges, a “non-floating” nail and controlled bleeding, could be evacuated by trephination alone. These studies did not demonstrate any increased evidence of cosmetic complications, soft tissue infection or osteomyelitis when compared to associated primary nail bed repair. Over the following 10 years, it was suggested that subungual hematomas involving less than 25% of the nail bed did not even require trephination. Over the past five years, however, this was disputed when studies suggested that complications were the same regardless of the size of the initial hematoma but were reduced when trephinated. The most recent studies therefore suggest that all simple subungual hematomas should undergo trephination. There is still wide variability in practice among ED physicians and hand surgeons [6,7,8].

Clinical Pearl: False acrylic nails can be flammable, so trephination with cautery is not a great idea. Usually acrylic nails are painted, so it’s difficult to diagnose the hematoma unless the nail is floating – and thus the acrylic nail is removed – or an 18G needle is used [10].

Conclusion
Injuries to the phalanges are often seen as quick “treat and street” encounters. Yet a failure to recognize many of the injury patterns discussed here can result in permanent functional disability.

Summary Pearls

  • Always assess digital viability. A threatened digit is a “real” emergency.
  • Assess and document flexion and extension at the DIP joint with focus on possible mallet and jersey tendon avulsions.
  • Have a high clinical suspicion for operative intervention in displaced longitudinal fractures.
  • Dorsal dislocations are often hyperextension injuries involving damage to the volar plate. Hyperextension during reduction can sometimes release the interposed volar plate tissue to allow successful reduction.
  • Subungual hematomas need trephination.
  • Nail bed injuries can be repaired with Dermabond.
  • Don’t trephinate through acrylic nails.

REFERENCES

  1. Swanson, Todd V., Robert M. Szabo, and Daniel D. Anderson. “Open hand fractures: prognosis and classification.” The Journal of Hand Surgery 16.1 (1991): 101-107.
  2. Swanson, Todd V., Robert M. Szabo, and Daniel D. Anderson. “Open hand fractures: prognosis and classification.” The Journal of Hand Surgery 16.1 (1991): 101-107.
  3. McLain, Robert F., Curtis Steyers, and Michael Stoddard. “Infections in open fractures of the hand.” The Journal of Hand Surgery 16.1 (1991): 108-112.
  4. Egol, Kenneth A., Kenneth J. Koval, and Joseph David Zuckerman. Handbook of Fractures. Lippincott Williams & Wilkins, 2010.
  5. Rockwood and Green’s Fractures in Adults. Philadelphia: Lippincott Williams & Wilkins, 2006.
  6. Roser SE, Gellman H. Comparison of nail bed repair versus nail trephination for subungual hematomas in children. J Hand Surg [Am]. 1999 Nov. 24(6):1166-70.
  7. Seaberg DC, Angelos WJ, Paris PM. Treatment of subungual hematomas with nail trephination: a prospective study. Am J Emerg Med. 1991 May. 9(3):209-10.
  8. Hart R, Uehara D, Wagner MJ. Emergency and Primary Care of the Hand. Dallas, Tex: American College of Emergency Physicians; 2001. 191-200.
  9. Strauss, Eric J., et al. A prospective, randomized, controlled trial of 2-octylcyanoacrylate versus suture repair for nail bed injuries. The Journal of hand surgery 33.2 (2008): 250-253.
  10. Gamston J. Subungual haematomas. Emerg Nurse. 2006 Nov. 14(7):26-34.

ABOUT THE AUTHOR

Christopher S. Courtney, MD is the Global Health Director of the Nothing to Lose Foundation and Research Fellow at the John Hopkins Bloomberg School of Public Health.

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