Module 7 - Hand Injuries

Hand Injuries


Given the complex nature of the anatomy of the hand, there are many different injuries and conditions that can affect its function. We will focus on the more common injuries and conditions seen in plastic surgery. For a more detailed discussion of each, please refer to the references at the end of this tutorial.

As in all areas of medicine, the history of a hand injury is very important. You must ascertain the mechanism of injury, hand dominance, occupation and previous hand injuries. In addition, you must obtain a full medical history, especially if you are considering surgical correction of an injury.

The hand examination is extensive; therefore you must approach it in an organized manner. You must be sure to inspect all surfaces of the hand. Be sure to note the color and posture, as well as any deformities, edema or lacerations.  One of the most important aspects of the hand exam is the neurovascular status.  The vascular integrity can be determined by capillary refill (normally <2sec, but should be compared bilaterally to account for such things as a cool extremity) and by performing an Allen’s test.  In the fingers, the most sensitive test for nerve damage is moving two-point discrimination. This must be done on both the ulnar and radial aspects of the fingers. Please refer to our Hand Examination Video for instruction on testing MSK function in the hand.

Important Hand Anatomy

  • Carpal Tunnel
    1. Boundaries
      • Carpal bones dorsally and laterally
      • Flexor Retinaculum volarly
    2. Contents
      • Median Nerve
      • Flexor Digitorum Profundus
      • Flexor Digitorum Superficialis
      • Flexor Pollicis Longus
  • Extensor Compartments
    1. Extensor Pollicis Brevis & Abductor Pollicis Longus
    2. Extensor Carpi Radialis Longus & Brevis
    3. Extensor Pollicis Longus
    4. Extensor Digitorum Communicans & Extensor Indicis Proprius
    5. Extensor Digiti Minimi
    6. Extensor Carpi Ulnaris

  • Innervation of the Hand
  • In the fingers, the nerves run volarly to the arteries.
  • Know the following distribution of the radial, ulnar and median nerves in the hand.

 
Anatomic Snuffbox – Bound medially by the EPL and laterally by the tendons of the 1st extensor compartment (APL & EPB). It is important because if there is a scaphoid fracture, it will be extremely tender in the “snuffbox”.
FDS & FDP – the FDS inserts on the distal aspect of the middle phalanx. The FDP inserts at the base of the distal phalange. The FDP runs deep to the FDS until the FDS splits in two, leaving a passage for the FDP to pass through the two branches of the FDS. This occurs over the proximal phalanx.
 

Amputations

Emergency care of the lacerated finger involves Tetanus prophylaxis, Irrigation, NPO Antibiotic Prophylaxis, and X-Rays. A mnemonic proposed in Toronto Notes (2005) to help remember these important steps is TIN-AX. The amputated part should be irrigated with saline and x-rays should be taken. It should be stored at 4 degrees Celsius (ie. On ice) and wrapped in a saline soaked piece of gauze.

When evaluating a patient for re-implantation, one should consider the following:

  • Hand Dominance
  • Occupation
  • Age
  • Level of Amputation
  • Number of digits amputated
  • Type of laceration (avulsion vs. guillotine)

Absolute Contrindications to Implantation:

  • Life threatening injury
  • Prolonged ischemia of the amputated part
  • Part in multiple pieces
  • Principles of Revision Amputation
  • When re-implantation is not indicated, one must consider the following principles of revision amputation:

If no exposed bone, healing by secondary intention gives the best results.
If bone is exposed:
  • Attempt to maintain length
  • Shorten bone until there is enough soft tissue coverage
  • Irrigate vigorously
  • “Bury” lacerated nerves in soft tissue to prevent the formation of painful neuromas.
  • Educate patients about desensitization of the healed stump.
  • Tendon Injuries & Finger Deformities

Mallet Finger – flexion of the DIP joint with the inability to extend the DIP joint caused by rupture of the extensor tendon or a fracture of the DIP resulting in release of the extensor tendon from the rest of the distal phalanx. Treatment involves splinting the DIP join in extension for no less than 6 weeks +/- surgical fixation of the extensor tendon to the distal phalanx.

Boutonniere Deformity – extension of the DIP joint and flexion of the PIP joint caused by synovitis at the PIP joint, which results in disruption of the extensor tendon from its insertion on the distal portion of the middle phalanx. Treatment options include synovectomy, correction of the central slip deformity, and arthrodesis/arthroplasty of the PIP joint.

Swan Neck Deformity – Flexion of the DIP and hyperextension of the PIP joint caused by injury to the PIP volar plate. Treatment involves splinting and arthrodesis/arthroplasty.

deQuervain’s Tenosynovitis – pain, tenderness and crepitation over the radial styloid process as a consequence of inflammation of the tendons in extensor compartment 1. Eliciting a positive Finkelstein’s Test identifies it. Treatment options include steroid injection and surgical release of the inflamed tendon sheath.

Ganglion Cyst – A mass in the wrist that is caused by a small tear in the intercarpal ligaments, which results in protrusion of a fluid-filled synovial lining. It is usually non-tender and fluctuates in size over time. It is treated with aspiration, excision, or steroid injection.

Trigger Finger (aka. Stenosing Tenosynovitis) – locking of the finer in either flexion or extension. It is caused by idiopathic inflammation of the synovium of the digital flexor tendon, which results in a size discrepancy between the tendon and its sheath/pulley. The ring, middle and ring fingers are most commonly affected. It is managed by surgical release of the synovium.

Hand, Wrist & Arm Fractures


There are several important fractures to know about in the hand. These are the Boxer’s, Bennett’s and Rolando’s fractures. During your plastic surgery rotation, you will undoubtly be asked about at least one of them. It is important, when evaluating a patient with a hand fracture, to identify any compromised tendons or neurovascular structures.

The Boxer’s fracture is a fracture at the neck of the metacarpal. It classically described in relation to the 5th metacarpal; however, the term can be applied to any of the metacarpals. It results from a blow to the distal aspect of a closed fist, for example when punching something. It causes angulation of the head of the metacarpal. In the small finger, angulation of up to 40o is acceptable because that metacarpal is mobile and can compensate for the angulation. The index and middle can tolerate 10o of angulation, whereas the ring finger can tolerate up to 30o.  On examination it is important to look for scissoring of the fingers when the patient makes a fist. If the fracture is stable it can be treated by with a splint. However, if it is unstable, surgical fixation is required.

Bennett’s fracture is an intraarticular fracture of the base of the thumb metacarpal. It is unstable. On examination the thumb is abducted because the APL creates tension on the metacarpal. This fracture requires surgical stabilization and a thumb spica.

Rolando’s fracture is similar to the Bennett’s fracture, in that it is an intraarticular fracture of the base of the thumb metacarpal. It is unique because it is a comminuted fracture that results in T or Y shaped fracture lines.  This type of fracture typically requires surgical stabilization.

Scaphoid fractures are the most common wrist fractures. They are important to identify because the unique blood supply to the scaphoid leaves it vulnerable to nonunion and necrosis. The blood supply to the scaphoid enters through the distal pole of the bone. The proximal part of the bone receives its blood supply via interosseous branches from the distal pole artery. Scaphoid fractures are commonly missed on x-ray, particularly if they are non-displaced. Tenderness in the anatomic snuffbox should make one suspicious of a scaphoid fracture. All suspected cases should be splinted and repeat x-rays should be performed after 1-2 weeks. Scaphoid fractures are treated with a splint or surgical fixation, where necessary.

Colles Fracture is a fracture of the distal radius. Specifically, it refers to an extra-articular fracture that results in dorsal displacement of the distal fragment and shortening of the radius.

Smith’s Fracture is also a fracture of the distal radius. It is similar to the Colles fracture, except that the distal segment is displaced volarly, rather than dorsally.

Hand Infections

Universal Signs of Infection :

  • Redness
  • Heat
  • Swelling
  • Pain
  • Loss of function.
  • Felon is a deep infection of the pad of the digit. It is treated with antibiotics and incision & rainage. If untreated, it may lead to osteomyelitis.

Paronychia is the most common hand infection. It is an infection of the tissue of the nail fold. It presents with pain, erythema and edema of the tissue. The most common organism causing acute paronychia is S. Aureus. The most common organism causing chronic paronychia is C. Albicans. Treatment is I&D, dressing changes, antibiotics or antifungal, and partial nail plate removal.

Herpetic Whitlow is an infection of the finger or fingertip by Herpes Simplex. It is usually self-limited and typically resolves in 3-4 weeks.

Necrotizing Faciitis is a severe, life-threatening infection, most commonly caused by Group A Beta Hemolytic Streptococcus. Immunocompromised, diabetic and elderly patients are at greatest risk for necrotizing fasciitis.  Treatment requires rapid, radical debridement of all necrotic tissue, with the wounds left open after debridement. The patient should be started on broad spectrum antibiotics and monitored in an ICU. I&D should be repeated every 24-48 hours until the sepsis has resolved.

Human Bites – Most common organisms are S. Aureus and Eikenella corrodens.

Dog & Cat Bites – Most common organisms are alpha-hemolytic streptococci, Pasturella Multocida, and S. Aureus.

Carpal Tunnel Syndrome
Carpal Tunnel Syndrome (CTS) is a progressive compression of the medial nerve as it passed through the carpal tunnel. It is the most common mononeuropathy. Risk factors for the development of CTS include:

Female
Pregnant
Diabetic
Rheumatoid Arthritis
CTS occurs as a result of inflammation and scarring within the carpal tunnel, which leads to relative anoxia and vascular compromise around the carpal tunnel. The signs and symptoms of CTS include:

Parasthesia of the hand in the median nerve distribution
Nocturnal pain & parasthesia
Pain & parasthesia aggravated by repetitive use
Positve Phalen & Tinel’s signs
Thenar wasting/weakness of the thenar muscles
CTS is treated by relieving the pressure on the medial nerve. This can be done by either splinting the wrist or by surgical release of the flexor retinaculum.