A Guide To Treating Crush Injuries
Crush syndrome is a term that describes the manifestations that occur after prolonged crushing pressure on the limbs.11,12 Manifestations are caused by the destruction of muscle tissue and the influx of myoglobin, potassium and phosphorus into the circulation. This can lead to hypovolemic shock, hyperkalemia and if, not treated, acute renal failure.11,13,14 This syndrome is unlikely to occur with an isolated crush injury of the foot, but more likely with an injury to one or both limbs.
Historically, the foot has been divided into four compartments: medial, lateral, central and interosseous.15,16 In 1990, Manoli and Weber demonstrated the presence of nine compartments: medial, lateral, superficial, adductor, calcaneus and four interosseous compartments.17 Researchers have suggested the presence of a tenth dorsal compartment containing the extensor digitorum brevis.18 The calcaneal compartment communicates with the deep posterior compartment of the leg, possibly allowing a concurrent compartment syndrome of the foot and leg.19
One should have a high index of suspicion of compartment syndrome when evaluating a crush injury. The most common physical findings you may see with compartment syndrome are relentless pain, loss of palpable pulses, decreased light touch sensation, impaired two-point discrimination, motor deficits and loss of pin prick sensation.4 However, keep in mind that you may not always note these findings with these patients.7
Measuring compartment pressures is the only method for definitively diagnosing a compartment syndrome.4,5,9 Normal compartmental pressure is 8 mmHg or less.9 You would perform a fasciotomy when compartmental pressure exceeds 30 mmHg or when the pressure reaches 10 to 30 mmHg below the diastolic blood pressure.20,21 One should perform a fasciotomy within eight hours of the injury and as soon as one makes the diagnosis.22
A variety of incisional approaches (including plantar, dorsal, plantar and lateral, and medial and dorsal) have been described for performing fasciotomies in the foot.5 Myerson recommends a combined two dorsal and one medial-plantar incision to decompress all nine compartments.9 The two dorsal incisions, located medial to the second metatarsal and lateral to the fourth metatarsal, allow one to release the adductor and interossei compartments.6 The medial plantar incision, located at the plantar medial aspect of the heel, allows access to the medial, lateral, superficial and calcaneal compartments.6 You should leave these incisions open.
Manage the wounds with wet to dry dressing changes for five to 10 days. Subsequently, one may perform delayed primary closure or provide coverage with split-thickness skin grafting.17
Key Essentials For Treatment
When treating crush injuries, one should begin by obtaining analgesia with a peripheral nerve block of the ankle. This should be done regardless of the magnitude of injury. This includes patients with compartment syndrome. This step does not alter decision making, but does significantly alleviate the patient’s pain.5 Keep in mind that a diagnosis of compartment syndrome is based on elevated compartment pressures and not on pain.4,23-25 Administer local anesthesia about the ankle with 20 cc of 0.5% bupivicaine without epinephrine.26
In order to minimize swelling, proceed to apply a bulky compressive dressing and elevate the foot if surgery is delayed or if you are planning on closed treatment.1 One can use a pneumatic intermittent compression foot pump to reduce swelling when elevation is not sufficient.5 Researchers have shown that using this pump is an effective method of reducing edema after lower extremity trauma.27 More specifically, studies have shown that the modality is successful in reducing edema associated with crush injuries of the foot.25,28 However, if you suspect that patients have compartment syndrome, be sure to measure compartment pressures prior to using the intermittent compression foot pump.1 One should continue to monitor patients for compartment syndrome while using the pump.5