Hand, Wrist, and Forearm Injuries



Hand, Wrist, and Forearm Injuries


Kenneth J. Noonan, MD, MHCDS

Donald Bae, MD1


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General Principles

Hand, wrist, and forearm injuries are among the most common injuries sustained by children. Although not life-threatening and usually not debilitating, they may be a frequent source of management trouble due to the sheer volume seen by most orthopaedists caring for children. Most injuries can be treated successfully and will heal uneventfully; however, careful attention to certain principles of diagnosis and management is critical to a consistently good outcome. In hand injuries, 75% create no problems, but 25% need careful diagnosis and treatment. To stay out of trouble, the orthopaedist must promptly recognize and treat problem fractures early.


Hand and Wrist Injuries

Although a pediatric orthopaedist or a general orthopaedist caring for children can handle the vast majority of hand injuries in children, it is important to know which cases should be transferred directly to a hand surgeon.


Physeal injuries represent 10% to 40% of all hand fractures. Fortunately, growth arrest is very rare. To stay out of trouble, it is important to recognize that an apparent “tendon disruption” may instead be a physeal fracture in a young child (Fig. 8-1). The flexor digitorum profundus inserts onto the distal phalanx and the flexor digitorum superficialis inserts onto the middle phalanx. The extensor tendons insert onto the epiphysis of the distal phalanges.

Evaluation of the pediatric hand can be challenging. It’s always a good idea to exam the uninjured hand first in order to gain trust. Questions should be general and with simple queries such as if the fingers feel sleepy or if they feel the same as the uninjured side. The tenodesis concept is critical to the examination. The orthopaedist should check the digital cascade at rest and with tenodesis wrist motion. This maneuver will call attention to the diagnosis of malrotated fractures and flexor tendon injuries. Fingers that don’t extend or flex with wrist flexion may indicate an occult tendon injury.


The orthopaedist should assess for the extent of open injuries, which can be subtle in the hand. Radiographs of a bleeding nail bed injury are needed to rule out an open growth plate fracture of the distal phalanx. Neurologic examination can be very difficult in children. One clue to a possible nerve injury is excessive bleeding from a wound around the area of the digital nerve, as the digital artery and nerve are often lacerated together. To stay out of trouble in assessing a nerve, it is helpful to do the “wrinkle test.” Immerse the digit in warm water for about 5
minutes. Denervated digits will not have any wrinkling of the volar skin, and over time, they will have altered sweat patterns (Fig. 8-2).







Figure 8-1 What looks like a tendon avulsion can be a growth plate injury in children.






Figure 8-2 This child has a median nerve palsy following a supracondylar humerus fracture. In addition to altered sensation in the median nerve distribution and weakened thenar function, his skin is dry with abnormal sweat pattern in the same distribution. (Used with the permission of the University of Wisconsin Division of Pediatric Orthopaedics.)


Radiographs of the injured palm and wrist should include an AP, lateral, and oblique views. More complex imaging is rarely needed. Evaluating an injured digit is done best by asking the radiology technician to focus on the finger as opposed to ordering hand films. A true lateral of the injured digit may be very valuable as opposed to a lateral of the hand, often with overlapping fingers that are nondiagnostic.

The treatment of any hand injury begins with proper pain control. Digital blocks are very effective for phalangeal fractures and nail bed injuries. To stay out of trouble, do not use epinephrine for digital block, as it may lead to distal ischemia. Also, never inject a circular weal around the digit as the circulation of the digit can be compromised.



Nail Bed Injuries

Nail bed injuries in children are common and can easily be missed. Plain radiographs should be obtained to assess for a concomitant fracture and the germinal matrix can be entrapped in the physeal fracture (the Seymour fracture; Fig. 8-3). The nail should be removed if it is not already off and can be placed in iodine solution for later use. Finger tourniquets can be helpful for visualization and eponychium incisions will allow you to extract the germinal matrix. The wound should be irrigated just like an open fracture. When you repair a nail bed in a child, use loupes and use #6-0 absorbable chromic suture. Stent the nail bed repair with Xeroform or the sterilized nail (if using the nail, put a hole in it to allow drainage).



Distal Phalangeal Injuries

Just like adults, children can jam their finger and suffer a “mallet finger” injury. As opposed to adults (where the extensor tendon is torn), forced flexion of the distal phalanx can result in a Salter Harris I or II injury with the extensor tendon
attached to the epiphysis while the profundus tendon flexes the distal piece. “Jersey finger” injuries usually occur in adolescents near skeletal maturity. The classic example is a football player whose finger gets caught in an opposing player’s jersey, leading to a profundus tendon avulsion.






Figure 8-3 Seymour fracture. The bleeding from the nail fold is directly adjacent to the widened growth plate seen on the radiograph. This is an open fracture and their may be interposed nail bed in the fracture.


AP, lateral, and oblique radiographs should be obtained to look for avulsion fractures entrapped in the pulley system or in the palm. To stay out of trouble, surgical intervention, within 7 to 10 days after injury, is usually required to reattach the tendon after a jersey finger injury.


Distal fingertip amputations and avulsions can be gruesome injuries, brought in by nauseated parents. If the parent brings the amputated part, it is important to assess its quality to decide whether replantation or a composite graft is warranted. When faced with a fingertip amputation you can offer the patient three choices based on the injury: (1) dressing changes for very distal injuries; (2) a composite grafting of the amputated part; or (3) replantation if the amputation is proximal to the DIP joint and the amputated part is in good condition.



Fractures of the Proximal and Middle Phalanx

Fractures of the proximal and middle phalanx in children can generally be managed successfully, but do present a few specific sources of trouble. Overall, most proximal and middle phalangeal fractures can be treated with nonoperative management utilizing reduction and casting for 3 to 4 weeks.

One important cause of problems is failure to recognize a rotational deformity (Fig. 8-4). All children should have splints removed, and an examination for rotational malalignment as described above is critical. Phalangeal neck
fractures are small injuries with big problems if not fully appreciated on true lateral radiographs. These fractures need closed reduction and percutaneous pinning. If the articular surface is allowed to heal in a dorsally displaced position, the child will have a permanent loss in flexion. Displaced intra-articular fractures can also lead to joint stiffness if not similarly reduced and pinned. Coronally angulated Salter-Harris (extra octave fracture) proximal phalangeal fractures of the small finger can remodel with growth severe angulated fractures will still require reduction.






Figure 8-4 The long finger has a proximal phalanx fracture in malrotation (black arrow). The other unaffected fingers more or less point in the same direction (white arrows) when they are flexed. (Used with permission of Dr. Nina Lightdale-Meric and the Children’s Orthopaedic Center, Los Angeles.)





Finger Dislocations

Although finger dislocations in young children are relatively rare, these injuries are not uncommon in the teenage athlete. To stay out of trouble, look for areas of open injury and do a good prereduction neurovascular examination. If the joint is irreducible, it is possible that there is an interposed ligament or volar plate hindering reduction. Open reduction may be necessary. After an injury to the volar plate, it is important to move the joint early. Do not do extension block splinting because you risk contracture of the child’s PIP joint.



Fractures of the Metacarpals

In children, the most common site of metacarpal fracture is the neck. Most can be treated with closed reduction and splinting. The physis in the metacarpal is distal, often very near the site of fracture, and remodeling will often correct the residual
deformity in young children. In those that don’t remodel, the malunion in the plane of joint motion is better tolerated than in the coronal plane.


Metacarpal shaft fractures must be evaluated carefully for malrotation. When the child makes a fist, all fingers should point to the scaphoid and all nail beds should be parallel. Unstable fractures with residual rotational malalignment may require closed reduction and percutaneous pinning. Fractures at the base of the finger metacarpals are infrequent in children. They are usually the result of high-energy trauma. In these cases, a CT scan is valuable. These injuries will often require either closed reduction and percutaneous pinning or open reduction and internal fixation.

Fractures at the base of the thumb metacarpal can present as simple transverse fractures or intra-articular fractures. Salter-Harris type III and IV fractures at the base most closely resemble the adult Bennett fracture. Fractures at the base of the thumb without intra-articular extension can be treated with closed reduction and immobilization. There is great remodeling potential at the base of the thumb because the fracture is juxtaphyseal and the carpal metacarpal joint has universal motion; angulation of up to 20° can be accepted.


Ulnar collateral ligament injuries of the thumb (a.k.a., gamekeeper’s thumb) are typically encountered in adolescents rather than young children. Similar to other injuries, the ulnar collateral ligament will be stronger than the adjacent bone, resulting in a Salter-Harris III avulsion fracture rather than ligament disruption. This is a “gamekeeper’s equivalent” and requires open reduction and internal fixation if displaced.



Fractures of the Carpal Bones

In general, fractures of the carpal bones in young children are exceedingly rare. The most common is a scaphoid fracture. Be alert to the fact that the scapholunate space may be physiologically wider in an immature child as there is unossified cartilage. This should not be mistaken for a perilunate injury. Comparison views will help define the normal space for the child that presents to you. To stay out of trouble with carpal bone injuries, any patient with pain in the snuffbox should be treated using a thumb spica cast for 10 to 14 days, even if the radiographs are negative. If still tender, MRI is now thought to be the best diagnostic test if there is a question of a scaphoid fracture and X-rays are equivocal. Proximal pole scaphoid fractures are rare but have a high risk of avascular necrosis (AVN). Distal pole fractures seem to heal with no problem. Fractures at the scaphoid waist are similar risks as in adults.




Fractures of the Forearm


FRACTURES OF THE DISTAL RADIUS AND ULNA

Fractures of the distal radius and ulna are exceedingly common in children. The keys to staying out of trouble include understanding remodeling, avoiding overtreatment, putting your reductions in good casts, and being alert for associated
injuries. Remodeling is greatest in young children, in fractures near a rapidly growing physis, in fractures that are in the plane of motion of the adjacent joint, and in fractures with greater amounts of angulation. Typically, the child can correct about 10° of apex-volar angulation for each year of growth remaining. Radial-ward angulation of the distal radius, caused by the pull of the brachioradialis, corrects more slowly. Bayonet apposition remodels reliably in younger children, especially those younger than about 8 years.



Physeal Injuries

Physeal injuries of the distal radius are the most common growth plate injury in children. To stay out of trouble, evaluate for open injuries, especially subtle pinpoint openings on the volar skin. Higher energy injuries, such as when a teenager falls rollerblading, can lead to neuropraxia of the median nerve, or even acute carpal tunnel syndrome or compartment syndrome1 (Fig. 8-5). To stay out of trouble, do a careful nerve examination and get these fractures reduced as quickly as is practical. The easiest injury to miss is the second injury, so be certain to evaluate the elbow and hand carefully when confronted with a distal radius fracture (Fig. 8-6).


Minimally displaced fractures are often placed in a splint and an Ace wrap in the emergency department and sent on to an orthopaedist office for management. NEWSFLASH! There are few things more dangerous than an inexperienced resident with an Ace bandage. A tight Ace wrap can be trouble (Fig. 8-7). Children will shift in the splint, or play with their Ace wrap, which can become rolled and cause a tourniquet-like effect. The Ace wrap can create a row of blisters at the seams between the Ace wrap or create a tremendous amount of swelling distally.


Displaced fractures can be reduced under conscious sedation at the time of injury. It is a general principle to avoid reductions or rereductions of physeal injuries later than approximately 10 days following injury, in order to avoid growth arrest. Open or closed reduction with Kirschner wire (K-wire) fixation
is used in special circumstances.2 To stay out of trouble with distal radius pinning, care should be taken to avoid the radial sensory nerve and the extensor tendons. Most agree that smooth K-wires across the physis are not a significant risk for growth arrest.3






Figure 8-5 This 14-year-old snowboarder was “catching some sweet air” when he stuck the landing and suffered this comminuted distal radius fracture. After reduction, he developed a compartment syndrome with an acute carpal tunnel syndrome as a result of the large volar bone fragment. (Used with the permission of the University of Wisconsin Division of Pediatric Orthopaedics.)






Figure 8-6 An 8-year-old boy fell and fractured his right wrist and underwent closed reduction and long arm casting. The family was pleased his wrist healed well but wondered why his elbow was crooked. In retrospect, he also had a type 2 supracondylar fracture that healed in a varus and extension. The treating team would have stayed out of trouble if they examined the joint above the fracture. (Used with the permission of the University of Wisconsin Division of Pediatric Orthopaedics.)


Up to 30° to 40° of dorsal angulation at the site of a distal radial physeal fracture will remodel satisfactorily in a child with more than 3 years of growth remaining (Fig. 8-8). Of course, this should not be the goal at the first reduction. However, if an 8-year-old returns to your office with 30° of angulation 10 days later, that can be accepted with an excellent result. The risk of growth arrest from a distal radius physeal fracture is considered to be 4%. However, the rate of growth arrest of a distal ulnar physeal fracture is 60%.4 Stay out of trouble by looking for radiographic growth arrest for a year after any ulnar physeal injury and in any patient whose radial physeal fracture underwent reduction.







Figure 8-7 This 5-year-old boy had a distal radius fracture, which was splinted in the emergency department 2 days prior to presentation. As often occurs, the Ace wrap rolled up around his wrist, creating a tourniquet effect and leading to dramatic hand swelling. His mother was more concerned about the hand than the wrist fracture. Fortunately, it was only 2 days.







Figure 8-8 This 12-year-old boy had a displaced physeal injury of the wrist that underwent reduction to about 50% translation (arrow). The treating physician knew he could get in trouble if he tried another reduction. After 2 years, the wrist was fully remodeled without signs of arrest. (Used with the permission of the University of Wisconsin Division of Pediatric Orthopedics.)


Metaphyseal Distal Radius and Ulnar Fractures

To stay out of trouble with these fractures, the clinician has to primarily understand which fractures have to be reduced and what aspects of displacement need to be reduced. As mentioned, a complete bayonet opposed radius fracture does not have to be reduced as long as angulation is acceptable. Putting a child through the pain and risk of a reduction is not justified to make an X-ray look pretty. Conversely, the adept clinician knows that 15° of dorsal angulation in an 8-year-old will remodel, but it won’t in a 14-year-old boy who is skeletally mature and who looks old enough to have a mortgage.


Nondisplaced or minimally displaced distal radial metaphyseal fractures can be treated in many ways with a good result. Some orthopaedists use splints and Ace wraps, some use removal Velcro splints, and many cast: in our experience, the least trouble occurs when a well-padded short arm cast is used.

For completely displaced fractures requiring closed reduction, it is important to understand how the thick pediatric periosteum can hurt you and help you. Distal radius fractures in children have tremendous remodeling potential, and this is due in great part to the biologically active periosteum. Mechanically speaking, the intact dorsal periosteum in a volarly angulated fracture can help hold your reduction. However, the periosteum can also hurt your reduction in fractures with bayonet apposition. In this instance, the proximal fragment can buttonhole through the periosteum, making reduction difficult (Fig. 8-9). In bayonet fractures with obliquity, it would be necessary to hyperdistract the fracture to translate the distal fragment volarly; the tough periosteum may make this almost impossible even for the strongest orthopaedic resident. Bayonet apposition in an 8-year-old is fine as long as angulation is minimal.

Jan 30, 2021 | Posted by in ORTHOPEDIC | Comments Off on Hand, Wrist, and Forearm Injuries
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