MORBIDITY FOLLOWING CRUSH INJURIES TO THE FOOT
August 4th, 1993
Mark S. Myerson, MD; William C. McGarvey, MD
Abstract
By retrospective review of hospital records and by follow-up clinical examinations, we evaluated 58 patients with crush injuries to the foot treated at our institution between 1986 and 1990. All patients had received initial treatment according to a standardized protocol determined by the type and magnitude of the injury. Patients were examined at a mean interval of 3.3 years (range, 2 to 4 years) after injury, and the functional outcome was determined according to a foot trauma rating scale.
Based on this scoring system, 46% of the patients had good functional outcome, 29% had fair results, and 25% had poor results. There was a significant correlation between a good functional outcome and careful adherence to the treatment protocol; however, some patients fared poorly regardless of treatment. Poor results occurred if treatment was not immediately initiated, if soft-tissue coverage was delayed (in those who experienced severe, mangling-type injuries necessitating partial foot amputation), if patients suffered from neuritis or reflex sympathetic dystrophy, or if patients were involved in ongoing workers' compensation and litigation.
We concluded that since crush injuries of the foot may be associated with prolonged morbidity, initial management should be directed toward recognition and treatment of compartment syndromes, early soft-tissue coverage, and rigid skeletal stabilization to enhance soft-tissue healing.
Introduction
In 1972, Omer and Pomerantz20 reported that 50% of their patients who sustained crushing injuries of the foot required assisted ambulation or had residual pain. Despite improvements in the treatment of soft-tissue trauma9,13,21,22 and increased attention to compartment syndromes of the foot,18,26 morbidity after these injuries remains high.
In 1986, we initiated a standardized treatment protocol for crush injuries of the foot, with strict attention to skeletal stabilization and early soft-tissue coverage. Despite what we considered optimal treatment, many patients had less than a satisfactory recovery. We therefore endeavored to evaluate more carefully the morbidity associated with these injuries and to highlight the results of treatment.
Materials and Methods
Patient Population
Each year, some 200 patients with isolated foot and ankle injuries are treated at our institution. Approximately 15% of these patients have sustained a crushing type of injury, i.e. trauma from an extrinsic compressive or shear force applied to the foot over a variable period of time.
Between 1986 and 1990, we treated 105 patients with acute crush injuries of the foot. We retrospectively reviewed their records and determined that there were 58 (55%) who met the criteria for inclusion in our study (age >16 at time of injury and isolated skeletal injury) and who were available for follow-up examinations. These 58 patients (44 men, 14 women) formed our study group. The average age at the time of injury was 35 years (range, 16 to 62 years).
The injuries were caused by: heavy falling objects (31); motor, industrial, or railway vehicles rolling over the foot (13); or crushing from industrial equipment (14). The injuries were further defined by the magnitude of trauma to the soft tissues and bone: compressive, shear, or mangling. Compressive injury (47) occurred when a heavy object fell on or came into contact with the foot; of these 47, 11 were minor compressive injuries predominantly involving the skin and subcutaneous tissues without fracture or dislocation, and 36 were more significant, with fracture or dislocation with or without an open wound. If the injuring object remained in contact with the foot for a prolonged period, bursting of plantar soft tissues occurred. Shear or degloving injury (six) occurred when a tangential force was applied to the surface of the foot, with avulsion of soft tissues. Mangling injury (five), with marked disruption of bone and soft tissues, was usually associated with industrial or railway accidents.
Compartment syndromes were recognized in 16 patients after injury from industrial equipment (11), crushing from a heavy object (three), or a motor vehicle rolling over the foot (two).
Management
All patients were treated according to a standardized protocol for crush injury and compartment syndrome of the foot. A routine history included the mechanism of injury and the events surrounding the accident, i.e. information about the injuring object and the manner in which the foot was affected, such as a quick blow versus extended contact. The physical examination included attention to the neurovascular status, notation of abrasions and penetrations of the skin, and measuring of pressures in all patients suspected of having compartment syndrome.11,12,15,26
After the initial examination, a regional ankle block was performed regardless of the type or magnitude of injury. This significantly alleviated patient discomfort and did not alter decision-making regarding treatment, even in the presence of a compartment syndrome. The ankle block was performed in a standard manner using 20 cc of 0.5% bupivacaine without epinephrine, as described previously.19 For minor open wounds, a first-generation cephalosporin was used, and gentamicin and clindamycin were added if significant visible dirt or debris was present. Anteroposterior, oblique, and lateral radiographs of the foot were obtained.
Twelve patients were managed by various non-operative modalities.
The remaining 46 patients underwent surgery for wound management (28), treatment of compartment syndrome with or without fracture or dislocation (16), or open reduction of a closed fracture or dislocation (two). Surgery was performed under general anesthesia (five) or regional ankle block anesthesia (41).
All compartment syndromes were treated with fasciotomy. The fasciotomy incisions were covered with porcine allograft or semisynthetic skin substitute, and closure was performed 5 to 7 days later with split-thickness skin grafts (12) or delayed primary closure (four).
Of the 58 patients, 28 (48%) had presented with open wounds, which were managed by: a combination of split-thickness skin excision (12), local rotation muscle flaps (four), bone shortening and partial amputation (four), free tissue transfer (three), split-thickness skin grafts (three), or healing by granulation and secondary closure (two). In 14 patients, the extended margin of tissue necrosis beyond the point of impact, which was not grossly visible (the zone of injury), was determined using fluorescein or split-thickness skin excision.13,21,27 Early coverage was felt to be important and was performed immediately in 17/28 patients. Free tissue transfer was performed 3 to 8 days after injury and depended more on the coordination of the microvascular team than on the status of the wound. Three significantly contaminated feet were treated with serial wound debridements and delayed closure; one was closed secondarily after a transmetatarsal amputation, and two were closed with split-thickness skin grafts 5 to 10 days after injury. Aggressive debridement and early coverage was attempted in five patients with open wounds seen between 48 and 72 hours postinjury, but was achieved in only one.
Skeletal stabilization was used for both wound management and fracture fixation in 28 patients: external fixation alone (nine), a combination of external and internal fixation with screws (four), internal fixation with screws alone (eight), and Kirschner wires alone or in combination with internal and external fixation (seven).
If closed treatment was planned or surgery was delayed, a bulky dressing was applied and the extremity was elevated to minimize swelling. If marked swelling was already present, a pneumatic intermittent compression device (AV Impulse System, Kendall, MA) was used to reduce swelling.18 Patients were hospitalized until satisfactory clinical recuperation was observed.
At follow-up examination (mean interval, 3.3 years postinjury; range, 2 to 4 years postinjury), particular emphasis was placed on range of motion of the ankle, midfoot, and forefoot joints and on sensory disturbances. Patients completed a questionnaire specific for trauma to the foot. A 100-point scale was established, with points assigned for pain (40), gait (20), instability (10), limp (10), shoes (10), terrain (5), and stair climbing (5). An overall score of 75 to 100 points was considered a good result; these patients experienced minimal functional limitation. A total of 50 to 74 points was considered a fair result; these patients experienced pain and functional impairment of daily activities. A score of less than 50 points was considered a poor outcome; these patients had significant complaints of both pain and functional impairment, they were often still involved in follow-up treatment (with therapy goals oriented toward adaptive function and pain control), and several were totally incapacitated.
Results
The results are presented according to the patient responses to the questionairre as well as physical examination. The findings on physical examination are not included in the results of the questionairre. According to the questionnaire responses, the 58 patients graded their results as follows: 27 (46%), good; 17 (29%), fair; and 14 (25%), poor. The results of treatment were further evaluated according to the type of injury, the presence of a compartment syndrome, the type of treatment initiated, delay between injury and treatment, work-related compensation, and ongoing litigation.
Ten patients had decreased active and passive range of motion of the hallux and lesser toes. Two of these patients sustained a compressive injury and a compartment syndrome, had been tretaed with fasciotomy though dorsal incisions, and the decreased motion was attributed to scar tissue about the extrinsic and intrinsic extensor tendons. Range of motion in the ankle was normal in all patients. Inversion and eversion was normal in 44 patients, decreased by 25% in eight, by 50% in four, and ankylosed in two. The appearance and sensbility of the soft tissues is discussed below with each group of patients separately.
As expected, the five patients with mangling injuries fared the worst (three poor, two fair results) as a group, since four of these patients required partial foot amputations. However, none of these patients experienced severe continued pain, and their functional outcome was determined more by the alteration in foot structure. Two patients in this group experienced pain from a stump neuroma that was successfully treated with excision.
Each of the wounds in the six patients with shear degloving injuries was treated with immediate soft-tissue coverage using split-thickness skin excision.13,21, There were no complications related to this method of coverage in these or in the other six patients treated with this technique. Of the six patients with degloving injuries, four had good and two had fair results.
Of the 47 patients who sustained a compressive-type injury, 36 sustained a fracture or dislocation and 11 had only more minor closed soft-tissue injuries.
Of the 36 patients with compressive injuries and fracture/dislocation, 19 had good, nine had fair, and eight had poor results. Of the 17 patients who had fair or poor results, one sustained a compartment syndrome, two required a free flap for coverage, five experienced problems with wound management, and four suffered from neuritis or reflex sympathetic dystrophy (RSD). There was no discernable source for the fair or poor result in the remaining five patients in this group. Of these 17 patients, eight were involved in unsettled workers' compensation claims and/or litigation compared to three of 19 patients in the same group who had good results.
Of the 11 patients with minor compression-type injuries from heavy falling objects without fracture or dislocation, four had good, four had fair, and three had poor results. In seven of these patients, injury was sustained while employed; four of those seven continue to be involved in workers' compensation and litigation claims. As discussed below, these 11 patients frequently experienced complications, such as neuritis and RSD.
Sixteen patients sustained a compartment syndrome. Of these, 11 had good, four had fair, and one had poor results. The range of motion in the midfoot and forefoot joints in these patients was normal, except for two patients in whom tethering of the extensor tendons to the skin occurred, limiting motion of the metatarsophalangeal joints. One patient with a fair and one with a poor result have pain from arthritis of the tarsometatarsal joints and are likely to undergo arthrodesis in the future. One patient with a fair result experienced pain from superficial peroneal neuritis as a result of a wound slough with diffuse scarring over the dorsal skin surface.
Thirteen patients experienced symptoms of neuritis or manifested features of RSD and, as a subgroup, did not do well. Eleven patients experienced burning and tingling associated with pain on light percussion of single or multiple areas of the foot. Two patients who sustained a mangling injury, necessitating amputation, experienced pain from a focal neuroma, but these symptoms were subsequently alleviated with excision of the neuroma. One additional patient with focal neurotic discomfort obtained no relief from excision of a neuroma in continuity. Three patients experienced neuritic dorsal pain in the distribution of the deep and superficial peroneal nerves. Two of these patients were treated late, and in one, coverage was delayed due to wound contamination. In these three patients, significant adherence of the skin to the subcutaneous tissues was present. Five patients experienced multifocal burning neuritic type pain that was refractory to non-operative treatment and was not thought to be amenable to excision of a neuroma. Four of these five patients had sustained comparatively minor compressive-type injuries in the work setting.
Two additional patients and two of the patients with diffuse multifocal neuritis manifested clinical findings of autonomic dysfunction. The diagnosis of RSD was confirmed if this pain was alleviated by lumbar sympathetic block and associated with positive scintigraphic findings on triple-phase bone scan.1,8 A sympathetic block was performed in seven patients for diagnostic and, in some instances, therapeutic purposes, and only if vague diffuse pain was associated with autonomic dysfunction. All four patients in whom the diagnosis of RSD was confirmed sustained relatively minor injuries. Two patients sustained a compressive-injury resulting in metatarsal fractures that did not require operative treatment. Swelling of the foot and cast immobilization was thought to have contributed to the development of RSD in one patient. Two patients sustained a minor compressive type injury, one of whom developed skin compromise the extent of which had not been initially appreciated. In the latter patient, the dorsal skin underwent necrosis, and following debridement and excision of a full thickness eschar, a split-thickness skin graft was applied.
The type of soft-tissue coverage used did not affect the outcome as much as the underlying condition that necessitated the coverage in the first place. The partial foot amputations that were performed in four patients were covered with a variety of methods; two of these patients had fair and two had poor results. Of the three patients treated with a free flap, two had fair and one had poor results; however, two of these patients had partial foot amputations, and the other was missing the lateral two metararsals, resulting in a gait disturbance.
Discussion
As Jupiter and colleagues have noted,9 limb salvage after severe crushing injuries is feasible, but frequently difficult to perform. Other authors have emphasized the importance of a standardized plan of treatment, incorporating principles of rigid skeletal fixation, early soft-tissue coverage, and aggressive rehabilitation to ensure the best possible outcome.2,4,16,17,24
Hardin and Robinson6 suggested that mechanical forces, length of time in contact with the limb, and direction of force vectors all contributed not only to the injury pattern but also to the severity of injury. Entin2 showed that with wringer injuries, the soft tissues that suffered maximally were those subject to greater forces for longer periods in multiple planes. Posch and Weller23 documented that appearance was not necessarily an indicator of severity, but that time in contact and forces applied were the factors of importance with respect to morbidity.
The treatment protocol outlined here is based on the premise that aggressive fracture stabilization and early soft-tissue coverage can decrease the morbidity after crush injuries of the foot. It has been shown that early debridement and soft-tissue coverage provides a lower infection rate and enhanced healing.2,6,7,16,20,24,25 The overall goal is to stabilize the injury, so that early rehabilitation can commence. Soft-tissue management begins with recognition of the zone of injury, which exists as an extended area of pathologic involvement surrounding the soft tissue and bone beyond the point of impact. At our institution, split-thickness skin excision is the standard for delineating avascular margins, predicting areas of deep tissue necrosis, and providing graft material for early soft-tissue coverage of open wounds.13,21
Despite strict adherence to these principles it is clear that the overall outcome after crush injuries of the foot in our patients was fair, albeit unpredictable. Because of the variability of the injury type in this series, the treatment was individualized according to a fairly comprehensive algorithm, and patients could not be realistically compared. Recognizing this variability has presented us with some difficulty in correlating or quantifying the results according to injury pattern or patient grouping.
Because no correlation existed between mechanism of injury and outcome, the treatment of crush injury of the foot, however trivial, should not be determined by or based on the mechanism of injury. It is apparent that the seemingly less severe compressive injuries carry their own inherent morbidity; in our series, some of the worst results occurred in the 11 patients who sustained relatively trivial injuries. Although these 11 patients did not have readily recognizable severe injuries, only four had good results, and half experienced residual pain. Yet in five of these 11 patients, the clinical findings at follow-up examination were unremarkable except for a constellation of neurologic findings, including dysesthesia and hyperesthesia beyond the point of impact. Electromyography and nerve conduction studies were normal in these five patients.
Neuroischemia may play a role in the development of chronic pain after crush injuries to the foot, either through direct trauma to the peripheral nerves or by intraneural or extraneural fibrosis after edema. A posttraumatic neuroma or resulting chronic neuritis may then serve as the trigger for RSD, the latter of which was present in four patients. Interestingly, all four patients with RSD sustained more minor compressive-type injuries. Regardless of the cause, the presence of ongoing pain limits the ability of the patient to pursue an active physical therapy program, resulting in further loss of motion and dysfunction.
There are certain conclusions that one may draw from this study. For example, although severe mangling type injuries may result in partial foot amputation, these patients may do well, and their disability may be more a result of functional impairment from partial foot amputation than from continued pain. The patients who sustained severe shear-type injuries with large degloving flaps13,21,22,27 generally did well (four good and two fair results). We attributed these results to immediate soft-tissue coverage with the technique of split-thickness skin excision, which not only accurately determined the zone of injury but which also supplied skin graft material. Despite the magnitude of the forces involved, only one of the 16 patients who sustained a compartment syndrome had a poor result. These patients were all treated similarly, with expeditious fasciotomy, rigid internal fixation of fracture or dislocation, and delayed wound coverage or closure. If untreated, compartment syndrome is associated with myoneural ischemia, which leads to significant problems in the foot.3,5,11,14,15 The problems our patients experienced, however, were caused by arthritis of the tarsometatarsal joints (two) or dorsal soft-tissue tethering (two).
It is apparent, therefore, that a variety of interrelated factors are likely responsible for the morbidity associated with crush injuries. For the severe shear, compressive, or mangling injuries, these factors are self-evident and include the loss of a viable soft-tissue envelope associated with a difficult-to-stabilize fracture or dislocation. Less severe contusions to the foot however, are also at risk secondary to nerve and other soft-tissue problems. Nevertheless, when management followed our recommended treatment protocol, the results were better than when it did not, e.g. the five patients with fair or poor results after delayed soft-tissue coverage or incorrect assessment of the zone of injury, resulting in wound complications, dorsal scarring, and neuritis. Ongoing litigation or continuing workers' compensation claims also seemed to contribute to the higher number of poor results in this group of patients.
This review highlights the broad spectrum of presentation of patients with crush injuries of the foot. Despite a comprehensive treatment protocol, functional results are not uniformly good. The prognosis after these injuries, particularly for compressive injuries, are unpredictable and an injury classification scheme does not appear helpful in predicting outcome. Patients sustaining crushing trauma to the foot do not have routinely favorable outcomes. These results may appear depressing, and suggest that the ability to influence the course of these problems is beyond the clinician's control. However, institution of prompt, comprehensive care may limit the complications and sequelae of these injuries to an acceptable level, allowing us to at least manage these patients more adroitly. Since these injuries are so diverse, it is not feasible that all are routinely treated in a tertiary care center. It is important for the initial treating physician to recognize the problem, and manage the injury according to the guidelines proposed here. Referral to a trauma specialist depends on good judgement as to the severity of the injury and when it is felt that proper care can no longer be rendered.
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