Compartment Syndromes of the foot
January 1st, 2003
Mark Myerson MD
It is interesting to note that prior to the early 1980’s there was very little attention paid to crushing injuries of the foot whether these were associated with compartment syndrome or not. It was not uncommon for surgeons to comment that if untreated, compartment syndromes of the foot were associated with little if any long term morbidity. While the deformity was recognized following injury to the foot, compared to the devastating losses after untreated compartment syndrome of the leg, the presence of “claw toe deformity” was not believed to be significant. This is clearly not the case, since the spectrum of problems after an untreated compartment syndrome of the foot is extensive. (1,2,3) Nerve deficits, including anesthesia, hyperesthesiae, and paresthesiae are common. In addition to these neurologic consequences, midfoot and forefoot deformities occur. Fibrosis of the intrinsic musculature causes severe toe deformities, which are quite refractory to correction. Occasionally following atrophy of the intrinsic muscles, flexible claw toe deformity is present, which are amenable to surgery.
However, the majority of forefoot deformities after compartment syndrome are extremely rigid, and contracture is present at both the metatarsophalangeal and the interphalangeal joints. This occurs as a result of fibrosis of the short flexor muscles, and these deformities are markedly rigid, and extremely difficult to treat. Correction of the soft tissue contracture by tendon lengthening, tenotomy, or release of the plantar plate does not correct deformity, nor increase mobility of the joints. Since the contracture is in the flexor brevis muscle, excision of these muscles would theoretically alleviate the deformity, however this is not practical in the foot. I have not had any success with managing these forefoot contractures with soft tissue releases, and bone shortening even with metatarsal head resection may be required to alleviate the pain from deformity (4).
Diagnosis
Compartment syndromes of the foot occur predominantly in the setting of crushing type injury, however, any high energy injury may lead to a compartment syndrome including those associated with calcaneus and midfoot fracture and dislocation. The diagnosis begins with recognizing and understanding the potential for compartment syndrome after these type of injuries. Most of these feet are very swollen and painful, although the type, extent and quality of the pain is not helpful with diagnosis. Although swelling of the foot occurs following all types of trauma, the swelling of the foot associated with a compartment syndrome is quite typical, and is tense, shiny and taught. However, evaluation of the perfusion and of sensory deficits of the foot is not reliable due to the swelling. I have found that the only clinically useful test is with passive dorsiflexion of the toes. To evaluate the foot compartments, all the toes including the hallux are dorsiflexed at the metatarsophalangeal joints, and by stretching the intrinsic muscles, severe pain is elicited if there is any ischemia present.
Although the history of a crush injury associated with marked tense swelling and pain on passive dorsiflexion of the toes is highly suggestive of a compartment syndrome, the diagnosis can only reliably be made with measurement of intracompartmental pressures. The needle is inserted into the dorsum of the foot, preferably in the second web space, which avoids inadvertent puncture of the deep peroneal nerve in the first web space. The needle is slowly pushed through the interosseous into the deep central compartment of the foot, measuring both compartments as it is advanced. The medial and lateral compartments can also be measured, depending on the readings of the interosseous and central compartment. It is painful to repeatedly insert the needle, and once one pressure recording is elevated, it is not necessary to proceed with measurement of the other compartments. If the medial compartment is measured, the needle is inserted through the abductor hallucis muscle, and then advanced into the deep central compartment. The same applies on the lateral side of the foot, although the lateral compartment is rarely measured in isolation.
Treatment
Once the compartment pressures have been measured, we use a regional ankle anesthetic block for pain relief. While there may be some reticence to use a regional block in the setting of severe injuries, this provides such significant relief to the patient, that we use it for all injury types, including those where compartment syndrome may be suspected. As noted above, the diagnosis of compartment syndrome should not be made on findings of pain, but upon elevated compartment pressure. If a compartment syndrome is present, then a fasciotomy is performed anyhow. The only time that we may not use a regional ankle block, is where monitoring of a potential compartment syndrome with repeated passive dorsiflexion of the toes is felt to be necessary. This is however unusual, and we will monitor the patient with repeated pressure measurements if the pressures are equivocal.
The foot does not tolerate a raised intracompartmental pressure that is in any way different from the leg, which makes sense, since the pathophysiology is identical, regardless of the size of the muscles compartments. The criteria for performing fasciotomy of the foot is therefore similar, and involve a combination of the compartment pressure measurement, the type and location of foot fracture or dislocation, and any trends in elevation of pressures. With a pressure greater than 40mm Hg in any of the foot compartments, fasciotomy is required. Pressures less than 20mm Hg are not significant, and do not warrant fasciotomy. For these patients we use a pneumatic intermittent compression foot pump, which has been documented to be an effective method to reduce edema associated with lower extremity trauma, and in reducing acute posttraumatic swelling associated with a crush foot injury (5). Patients seem to tolerate the sensation of pressure of the pump without difficulty, and the pain is effectively managed with the regional ankle anesthetic block. Clearly however, these patients need to be monitored closely. Following administration of a regional ankle block, the foot pump is applied, and the foot examined hourly until the swelling decreases at which time the concern for a compartment syndrome is not present.
Pressures ranging from 30mm-40mm Hg can be treated with fasciotomy or by close monitoring depending on the presence and pattern of fracture or dislocation. For example if the pressure is 30mm Hg and a tarsometatarsal dislocation which requires fixation is present, I would perform fasciotomy. Since surgery is being performed anyhow, there is minimal added morbidity from the fasciotomy incisions. This principle does not however apply to calcaneus fractures associated with elevated compartment pressures.
The treatment of compartment syndrome associated with calcaneus fracture is controversial (6,7). One the one hand, fasciotomy would normally be required for markedly elevated pressures, however this converts the injury into an open fracture, with a higher potential for infection. Open reduction and internal fixation of the fracture cannot be performed simultaneously due to the marked swelling present. If fracture care is necessary, surgery should be delayed for ten to fourteen days, when surgery can safely be performed, and wound complications are minimized. We have in the past applied an intermittent foot compression pump routinely to treat calcaneus fractures to expedite fracture care, and found that the intracompartmental pressures decreased rapidly with the application of the foot pump. We have since been less inclined to perform fasciotomy associated with a calcaneus fracture, and routinely apply the foot pump to decrease swelling, which simultaneously decreases the intracompartmental pressures. There are however patients with a calcaneus fracture who present with exquisite pain associated with severe neuritic symptoms due to an acute tarsal tunnel syndrome. For these patients, decompression of the tarsal canal in conjunction with fasciotomy should be performed.
Fasciotomy
Once diagnosed, a compartment syndrome must be treated with fasciotomy without delay. The approach to fasciotomy can be either through dorsal or medial incisions, or rarely, using a combined approach. The dorsal approach is made with as wide a skin bridge as possible between the two incisions. When making these incisions it may seem that there is quite sufficient skin between them, but following fasciotomy with relaxation of the skin, the bridge is surprisingly narrow. The one incision is made along the medial edge of the second metatarsal, and the second, lateral to the fourth metatarsal. The incision is deepened through subcutaneous tissue with blunt dissection, and no retraction or dissection is performed on the central skin flap to prevent dehiscence. The extensor fascia is perforated with a blunt clamp which is then passed through the interosseous compartments between the metatarsals and then deeper into the central compartment. The same maneuver is performed with the lateral incision, turning the clamp both medially and laterally to complete the fasciotomy. It has not seemed necessary to perform any deep dissection once the compartments have been released as described above. Following crush injury, particularly when a midfoot fracture is present, the limiting fascial compartments seem to be torn, and there is communication between the various foot compartments. Following the first dorsal fasciotomy incision, the hematoma is expressed, and the swelling of the foot immediately decreases. Although the lateral fasciotomy incision should nonetheless always be performed, one notes less hematoma expressed from the second, lateral decompression. For the same reason, following insertion of the clamp into either interosseous space dorsally, it is not necessary to aggressively manipulate the clamp in the central compartment.
We prefer to use the medial fasciotomy incision when there is no fracture or dislocation of the midfoot. The incision is made along the length of the first metatarsal, and the abductor fascia incised, which decompresses the medial compartment. To enter the deep central compartment, the dissection is performed by elevating and retracting the abductor hallucis muscle dorsally, and perforating the deep fascia with a blunt clamp. This incision may be extended proximally to decompress the entire tarsal canal, if for example the compartment syndrome is associated with an acute tarsal tunnel syndrome.
Coverage of the fasciotomy is not initially necessary, and closure of the incision following fasciotomy certainly should not be performed. I use wet to dry dressings performed twice daily with saline for the first week, and then close the incisions if the skin margins have not retracted. The skin on the medial foot is thicker than the dorsal skin surface, and closure with sutures is possible. On the dorsal foot surface however, split thickness skin graft is preferable. These grafts contract over time, and the cosmetic defect is minimal.
Discussion
Compartment syndromes of the foot occur frequently associated with a crush type injury. Although the crushing force does not always occur perpendicular to the surface of the foot, as for example with a heavy object falling on the foot, the extrinsic compressive force is typically applied to the foot over a prolonged time period, and the crushing object is often broad and heavy, as for example in the industrial setting. A variant of this type of crushing injury occurs when the compressive force comes into contact with the foot quickly, squeezing, and crushing the tissues, causing a bursting of the soft tissues on the plantar foot surface. It is important to note that a compartment syndrome may occur in these open injuries as well. These type of injuries may decompress the hematoma, but while compartment syndromes occur less frequently in this setting, we have identified them associated with open fractures nonetheless. Compartment syndrome of the foot occurs in children, and the treatment of these injuries is no different than that in the adult foot (8).
Although this review has focused on compartment syndromes, the approach to management of crush injuries of the foot is similar whether or not a compartment syndrome is present. Following measurement of compartment pressures, soft tissue coverage and skeletal stabilization are of paramount importance (9,10).
References
1. Myerson MS. Management of compartment syndromes of the foot. Clin Orthop 1991; 271:239-248.
2. Myerson MS: Experimental decompression of the fascial compartments of the foot the basis for fasciotomy in acute compartment syndromes. Foot Ankle 8(6):308 314, 1988
3. Myerson M. Crush injuries and compartment syndromes of the foot. Int J Orthop Trauma 1993; 3:109-113
4. Myerson MS. Crush injuries and compartment syndromes of the foot. In: Myerson MS (Ed). Disorders of the Foot and Ankle. WB Saunders. Philadelphia, 2000.
5. Myerson MS, Henderson MR. Clinical applications of a pneumatic intermittent impulse compression device after trauma and major surgery to the foot and ankle. Foot Ankle 1993; 14:198-203.
6. Myerson M, Manoli A: Compartment syndromes of the foot after calcaneal fractures. Clin Orthop 290:142 150, 1993
7. Myerson MS, Juliano PJ, Koman JD. The use of a pneumatic intermittent impulse compression device in the treatment of calcaneus fractures. Mil Med 2000, 165(10), 721-5
8. Silas SI, Herzenberg JE, Myerson MS, Sponseller PD: Compartment syndrome of the foot in children. J Bone Joint Surg 77A:356 361, 1995
9. Myerson MS, McGarvey WC, Henderson MR, Hakim J. Morbidity after crush injuries to the foot. J Orthop Trauma 1994; 8:343-349.
10. Myerson M. Split-thickness skin excision: its use for immediate wound care in crush injuries of the foot. Foot Ankle 1989; 10:54-60.
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