Foot



Foot


Maya Pring

Vidyadhar Upasani



INTRODUCTION

Foot fractures account for 5%-10% of pediatric fractures, and many of these can be treated with benign neglect and do relatively well. However, a missed midfoot fracture or hindfoot dislocation can lead to significant long-term disability. In many cases, the magnitude of the soft tissue injury may be more significant than the fracture. A thorough physical exam and careful imaging to evaluate fractures in three dimensions are needed to ensure you don’t miss injuries that can lead to problems.

“The thing that’s important to know is that you never know. You’re always sort of feeling your way”

Diane Arbus


“Check the skin carefully; open foot fractures may be missed if the laceration is on the plantar or posterior aspect of the foot”






Figure 17-1 Compartments of the foot.






Figure 17-2 Arches of the foot.


ASSESSING THE PATIENT

Knowing the mechanism of injury can improve your evaluation. Getting the toe caught on the doorframe or a trip and fall requires a much more limited evaluation than a motocross injury. For low-energy injuries or occult fractures, you should be able to localize a fracture with observation and a single finger to push on the areas thought to be injured—cuboid fractures are a classic missed fracture in the foot. Toe fractures usually present with a very swollen, sometimes crooked toe.

High-energy injuries to the foot may also cause damage to the ankle, knee, hip, and spine—do not focus on the obvious distal swelling, instead look for other injuries—it is not uncommon to find ligament injuries and fractures above. The foot has very small, tight compartments that do not tolerate much expansion before developing compartment syndrome—if you have any concern, measure compartment pressures.

Check the skin carefully; open foot fractures may be missed if the laceration is on the plantar or posterior aspect of the foot. Pulses should be symmetric to the contralateral side, if you cannot find pulses manually or with Doppler, try to determine what is compromising blood flow—swelling in the foot or leg, vascular injury, joint dislocation?

Open fractures resulting from a lawn mower injury are relatively common in parts of North America where children love to play on and around the lawn mower. These injuries often involve partial amputations and are very dirty wounds that may require multiple debridements before getting a plastic surgeon involved for a skin graft or flap.


ANATOMY

Each human foot has 26 bones, 33 joints, and 107 ligaments. There is some debate as to how many separate compartments there are in the foot: the compartments in Figure 17-1 should be considered when there is concern for foot compartment syndrome.






FOREFOOT FRACTURES AND DISLOCATIONS


Phalangeal Fractures

Modern culture provides a variety of opportunities for toe fractures ranging from a television falling on a toe to kicking your sibling (Fig. 17-4). The pain makes shoe wear very difficult, the x-rays may be uncertain, and the patient requires your care and attention even though the problem may seem small to you.

Simple phalangeal fractures require protection to allow healing. This protection may range from simple taping, taping plus a hard-soled or “post-op” shoe versus a well-molded short leg (below knee) cast. The choice of immobilization method is often determined by the patient and family’s temperament and the child’s response to pain. For a simple phalangeal fracture treated with taping, follow up may not be required because post-healing x-rays are rarely needed. When the toe stops hurting, they can go back to activities—usually in 3-4 weeks. It is important to teach the family to check the toes regularly as tape can cut off the circulation turning a small injury into disaster if it is not recognized. We don’t recommend taping if the child is not old enough to take the tape off if the toes become painful or numb.

On occasion, a toe fracture is significantly angulated (especially Salter-Harris II fracture—proximal phalanx) and requires reduction. The “digital block plus pencil as fulcrum” reduction method used for fingers also works well for toe fractures. Taping the toe to the adjacent one will maintain alignment.

Some toe fractures are not reducible because of soft tissue interposition or are very unstable and will not maintain a reduction; for these fractures and open fractures, a trip to the operating room may be indicated. Reduction may be achieved by closed manipulation; sometimes a towel clamp can be used to aid reduction in a very swollen toe. Percutaneous K-wire fixation will then stabilize the fracture. Small,
fine K-wires are used to stabilize the fracture in its reduced position. If the fracture cannot be reduced by closed means, open reduction is indicated followed by fixation with fine K-wires.






Figure 17-3 CT can help delineate pathologic lesions that may lead to fracture. This unicameral bone cyst has a very thin cortex superiorly with impending fracture.

“We don’t recommend taping if the child is not old enough to take the tape off if the toes become painful or numb”






Figure 17-4 These phalanx fractures were treated with a short leg walking cast.






Figure 17-5 Open fracture/crush injury of the great toe involving the physis.






Figure 17-6 This vertical cleft, often seen following a kicking injury, can be an epiphyseal injury or a normal variant. Contralateral films may help you decide.

If the fracture has to be opened, incision should protect the tendon and neurovascular bundles. The pin can be inserted through the fracture and driven out distally, then the fracture is reduced and the pin driven back in a retrograde fashion. The pin should be cut short and bent outside the skin for easy removal in clinic—make sure the cast covers the pin as children may pull the pin out if they can see it. The child should not bear weight with pins in the foot (the pins can break) so if they are not trust-worthy, we put them in a long leg cast with the knee bent to 90 degrees to protect the foot.


Problem Fractures—Great Toe

Growth arrest is occasionally seen as a late consequence after stubbing of the great toe, likely due to an occult Salter-Harris V physeal injury. Depending on the age of the child, they may end up with a short great toe which functionally is not usually a problem, but cosmetically may be displeasing (Fig. 17-5).

With hyper-flexion (tripping over the toe while running barefoot), the great toe distal phalanx may sustain an open Salter-Harris I fracture of the distal phalanx with damage to the nail bed and matrix. If the proximal part of the nail is lifted out of the skin fold along with physeal disruption, this should be considered an open fracture. The nail matrix may get caught in the fracture and cause poor nail growth. As with any open fracture, infection may follow without adequate irrigation and debridement. These fractures should be recognized as open injuries and carefully cleaned, nail matrix lifted out of the fracture before reduction, consider pin fixation and a cast to prevent loss of reduction, and further injury to the matrix. The patient should be treated with appropriate antibiotics.

Displaced, intra-articular fractures of the great toe proximal phalanx, a common injury in soccer and other sports, are often under-treated. On occasion, there may be difficulty in determining whether the child has a normal vertical cleft or a physeal fracture (Fig. 17-6).

All intra-articular fractures have a risk for non-union, and this important joint is no exception. As in any intra-articular fracture, a gap of less than 2 mm and no articular step-off may allow cast treatment only (cast past tip of great toe, dorsal and plantar, to optimize immobilization—non-weight bearing for 3 weeks, then weight bearing). Interim x-ray checks are required to rule out loss of reduction. Fractures within the gray zone of 2 mm of displacement may need a fine cut CT scan to make a final decision regarding the need for operative treatment. With significant displacement, fixation is recommended (Fig. 17-7).


Old non-unions often persist with symptoms and a relatively smooth longitudinal line crossing the proximal phalanx epiphysis. A cast can be tried, but internal fixation may be needed to achieve union.


Dislocations

The interphalangeal joints and metatarsophalangeal joints can dislocate with or without a fracture. Most commonly, these can be reduced in a closed fashion and do not require open reduction or internal fixation. Very rarely, there is soft tissue interposition that blocks reduction, and open reduction is necessary; this can be done with a relatively small incision medial or lateral to the joint. A “freer” elevator is used to replace the soft tissue anatomically, which allows reduction of the joint. The reduction is usually stable, but the foot should be protected with a cast or hard-soled shoe for 2-3 weeks (Fig. 17-8).


Metatarsal Fractures

Current childhood culture that includes aggressive skateboarding, dirt-bike racing, and television inspired jumps often from dizzying heights makes foot fractures common, especially metatarsal fractures.


Shaft and Neck Fractures

Minimally displaced metatarsal fractures can be treated simply by immobilization in a short-leg walking cast for 3-6 weeks depending on the child’s age and activity level (Fig. 17-9). The cast is split widely for the first week to allow for swelling. In cases with severe swelling, a well-padded (bulky Jones) splint may be needed for the first week.

If there is significant angulation or translation of a metatarsal neck fracture, it may require closed versus open reduction and pin fixation followed by casting. The amount of acceptable angulation decreases
with increasing age as the potential to remodel decreases. You may accept 45 degrees of angulation in a 4-year-old, but in a teenager, more anatomic reduction is required.






Figure 17-7 Intra-articular Salter-Harris III fractures need to be anatomically reduced to minimize the risk of metatarsophalangeal joint arthritis.






Figure 17-8 Oblique and lateral views may be helpful in diagnosing a toe dislocation.






Figure 17-9 Initial and 1-year follow-up AP x-rays in a teenage boy with second and third metatarsal fractures treated in a short leg cast with toe plate. Remodeling of the fractures has allowed normal function.






Figure 17-10 The compartments of the foot can be released with 3 incisions.






Figure 17-11 Older patients can tolerate less angulation in metatarsal fractures.

The second metatarsal tends to be the longest metatarsal and is at highest risk of stress fracture and Freiberg infraction (Avascular necrosis [AVN] of the metatarsal head).


Multiple Metatarsal Fractures

The often high-energy nature of these injuries (as well as the foot being naturally dependent) may lead to marked swelling with metatarsal fractures. Compartment syndrome can involve the interossei and short plantar muscles. Compartment syndromes of the foot can occur with severe fractures and must be recognized. There is debate in the literature as to whether fasciotomies of the foot lead to better outcomes. As discussed in the anatomy section, there are multiple foot compartments (±9) that can be effected. These can be released with two dorsal incisions, one over the second metatarsal and one over the 4th and a third incision medial to the calcaneus if needed (see Fig. 17-10). Incisions can usually be closed without skin grafting once the foot swelling resolves.

However, a recent study by Bedigrew of military injuries showed that fasciotomies did not prevent neuropathic pain and deformities in adult patients with compartment syndrome—it is unclear if these data translates to the pediatric population as the injuries in children do not tend to be as high energy as the blast injuries seen in the military. We still consider fasciotomies for children with foot compartment syndrome (intracompartment pressure greater than 30 mm Hg).

Multiple, displaced metatarsal fractures may require reduction and fixation depending on the age of the patient and whether the first and fifth metatarsals are involved. It is important to maintain the transverse and longitudinal arches of the forefoot and to align the metatarsal heads to maintain appropriate forces going through the foot and prevent transfer metatarsalgia.

If the intermetatarsal ligaments are disrupted, it may be difficult to maintain alignment of multiple metatarsal fractures. If the border metatarsals are intact, and there is no ligamentous injury, the width and stability of the foot will be maintained even with a fair amount of displacement of the middle metatarsals. Flexion and extension deformities tend to remodel better than abduction/adduction. The abduction deformities can also widen the foot making shoe fitting more difficult.

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Nov 17, 2018 | Posted by in PATHOLOGY & LABORATORY MEDICINE | Comments Off on Foot
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