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ORIGINAL ARTICLE  
Year : 2013  |  Volume : 6  |  Issue : 1  |  Page : 29-36
Blast injuries to the hand: Pathomechanics, patterns and treatment


Department of Plastic and Reconstructive Surgery, Institute of Post Graduate Medical Education and Research, Kolkata, India

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Date of Submission28-Dec-2011
Date of Acceptance17-Jul-2011
Date of Web Publication22-Jan-2013
 

   Abstract 

Purpose: To characterize the common patterns of injury in detail in cases of blast injuries to the hand and to outline the possible pathomechanics of these patterns of injury while describing the treatment modalities for the same as practiced in our center. Materials and Methods: A review of admitted patients in our department from september 2009 through december 2010 of blast injuries to the hand was made. Each patient had a careful characterization of their injuries as mild, moderate or severe with the help of X-rays, clinical photographs and operative notes. The treatment of these patients during hospital stay was also documented. Results: Of the 55 patients studied, 5 patients suffered mild injuries with no bony injuries or dislocations, 26 patients had moderate injuries characterized by fractures and dislocations in addition to soft tissue injuries and 24 patients had severe injuries characterized by variable degrees of amputations. The most common injury type was to the radial aspect of the hand characterized by a first web split and a dislocation of the CMC joint of the thumb associated with fracture of the central metacarpals and amputations of the index and long fingers in some cases. Injury to the ulnar aspect was rare. Injuries were treated by repair as well as replacement done mostly in a serial fashion. Conclusion: Depending on the mode of injury, blast injuries to the hand can have varying patterns of injury, which can have important implications in the treatment and rehabilitation of a patient.

Keywords: Blast, hand, injury, pattern, pathomechanics

How to cite this article:
Adhikari S, Bandyopadhyay T, Sarkar T, Saha JK. Blast injuries to the hand: Pathomechanics, patterns and treatment. J Emerg Trauma Shock 2013;6:29-36

How to cite this URL:
Adhikari S, Bandyopadhyay T, Sarkar T, Saha JK. Blast injuries to the hand: Pathomechanics, patterns and treatment. J Emerg Trauma Shock [serial online] 2013 [cited 2020 May 31];6:29-36. Available from: http://www.onlinejets.org/text.asp?2013/6/1/29/106322



   Introduction Top


Blast injuries, which have usually been associated with war and now with terrorist attacks, can have disastrous consequences. [1] In India, there are several patients being referred to tertiary care hospitals with blast injuries. The pattern of these injuries are quite different from those of large scale blast injuries because in most cases these blast injuries occur from firecrackers and homemade bombs, which have a variable blast potential with low intensity explosives deflagrating at rates up to 400 m/s and high intensity explosives deflagrating at rates varying from 1000-9000 m/s. [2] Plastic surgeons are frequently involved in the primary care of these patients as many such injuries involve the hand. The predominance of the hand in involvement in such injuries is due to accidental blast during hurling a bomb as well as the injury sustained when a person tries to shield himself from a bomb being hurled at him with his hands. Most of these injuries occur as a result of political and interpersonal rivalry although some cases are due to attempted robbery. The purpose of this study was to define the most common pattern of injuries in cases of hand injuries due to blast and to outline the pathomechanics of bomb blast injuries to the hand and the treatment plan in our series.


   Materials and Methods Top


A review was made of admitted patients of hand injuries from blasts in our department from september 2009 through december 2010. An analysis of clinical notes, X-rays, and operative findings of the patients supplemented with clinical photographs was made to arrive at the different aspects of hand injuries in these patients. A total number of 55 patients were admitted in our department because of blast injuries to their hands and other regions in this interval and all of them were included in the study. Patients were categorized into various socioeconomic groups based on the SEC classification system in India. [3] All these patients had detailed clinical notes, X-rays, operative notes, and clinical photographs. Most commonly, patients suffered hand injuries while holding an explosive in their hands, while a few suffered injuries when attempting to shield themselves from an explosive being hurled at them. However, the actual number of these two subgroups of patients was not discernible.

All of these injuries occurred from commercially available as well as homemade explosives, which varied in their intensity. A pipe bomb comprises a section of pipe filled with explosive material with pipe fragments creating potentially lethal shrapnel. A bottle bomb comprises a variety of explosive agents, usually chemicals contained within a bottle. A firecracker is a small type of explosive device containing a fuse, which makes a loud sound on explosion. Black powder, also known as gunpowder, is a mixture containing sulfur, charcoal, and potassium nitrate. Homemade bombs are explosives of variable blast potential made of a variety of agents. A gunshot wound occurs from the discharge of a firearm.

A quick history was taken following which the patients were taken to the operating room as early as possible. We classified injuries as mild, moderate, and severe according to the various patterns noted and the feasibility of management. Patients with mild injuries had only involvement of the soft tissues with no involvement of bone or joints which permitted early motion after repair and an excellent outcome. Moderate injury was described in patients having injuries to bones and joints in addition to soft tissues but no amputations of any kind so that the eventual outcome was satisfactory with some degree of residual stiffness in the hand. Patients with severe injuries had amputations of part or whole of the hand, which led to terminalization operations in many cases and to severe disability and stiffness. Blast injuries of the hand were treated with both repair and replacement depending on the extent of the injury, which was highly variable. The primary aim of management was maximal preservation of function. [4]

All patients were subjected to primary debridement followed by primary closure if possible. In others, serial debridement followed by either healing by secondary intention or definitive flap coverage was done. Joint disruptions were managed with K-wire fixation on an immediate basis and associated reconstruction. Fractures were managed with definitive wound closure followed by fixation with either K-wire or miniplates. Amputations were managed with terminalization operations done either primarily or in a serial fashion.

All patients except those with a terminalization operation proceeded to an immediate intensive postoperative physiotherapy program and were subsequently rehabilitated.


   Results Top


A variety of etiologic agents were noted causing blast injuries of the hand the most common being firecrackers, homemade bomb and bottle bomb. These caused a spectrum of injuries ranging from mild to severe which, we surmise, were due to variable blast potentials and differing distance of the explosive from the hand at the time of the blast. The spectrum ranged from soft tissue injuries to amputations of the whole hand. The degree of injury varied with the etiologic agent with firecrackers causing the widest range of injuries. In the injury mechanism, a mild type of injury was caused only by firecrackers and black powder in our series. Other agents resulted in moderate and severe injuries [Table 1].
Table 1: Injury descriptions with management


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In our series, 100% of the patients were male underscoring the part played by males in hostile encounters in this part of the world. The age range was 13-56 years with an average of 27 years. Most of the patients were from BPL (Below Poverty Limit) (40%) and poor (40%) categories with the rest comprising low middle class (16%) and middle class (4%) categories. People from upper middle and affluent classes were not encountered in our hospital during the period of the study. About 38% patients were illiterate. The dominant hand was involved in 82% of cases (45 patients) with bilateral hand injuries being encountered in 16% of patients (9 patients) and only 1 patient (2%) had injury of only the non-dominant hand.

Associated injuries included soft tissue and bony injuries to the face (25.5%), the torso (21.8%), the forearm and arm (14.5%) and the genitals (1.8%). It was conspicuous that no injuries to the lower limbs were noted in any patient. Associated injuries comprised mostly of a combination of superficial and deep burn injuries with soft tissue lacerations in some cases distributed over the face, torso and upper limbs. It was surprising that even in cases with severe injuries, the brunt of the injury was borne by the hand with no visceral injury in any form whatsoever either to the thorax or to the abdomen. Injuries to the thorax and abdomen comprised of a combination of burn and soft tissue injuries only. It might be possible that severe thoracoabdominal injuries arising from blast injuries were referred to the concerned specialties in the first place and were therefore not encountered by the plastic surgeons. In a case with amputation of the major part of the hand following a blast injury, the patient had associated maxillary fracture, globe rupture, and fractured both bones of the same side of the forearm. No other patient had any other bony injuries apart from the hand.

Overall, mild injury [Figure 1] was noted only in five cases in our series; moderate [Figure 2] and severe cases [Figure 3] were overwhelming and totaled 50 (90.91%) including 24 (43.64%) severe injury cases. In young adults in the age range of 21-30 years, 34 (61.82%) victims were noted; in less than 30 years were 41 (74.54%). However, the number of patients with severe injury less than 30 years was not significantly higher (Chi square 3.256, P = 0.0712) [Table 2].
Table 2: Epidemiology of Injury


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Figure 1: Mild type of blast injury characterized by superficial burn injury only

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Figure 2: A moderate type of blast injury of the hand; a split of the 1st web space with amputation of the tip of long finger as well as disruption of carpo-metacarpal (CMC) joint of thumb

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Figure 3: Severe type of blast injury characterized by gross soft tissue injury and varying levels of amputations of fingers

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The proportion of injuries to the thenar muscles and 1 st web space were considerable with >98% of patients being affected. A review of [Table 3] also showed a large proportion of injuries to the radial aspect and the center of the hand which tapered off when one moved to the ulnar aspect of the hand. Metacarpal fractures were more common than MCP (metacarpo-phalangeal) joint dislocations in the center of the hand with amputations being less common [Table 3].
Table 3: Injury proportions


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When McNemar's test was applied for paired variables, it was found that there was good correlation of injuries to the 1 st , 2 nd , and 3 rd rays overall (weighted Kappa values of 0.49, 0.46, and 0.78). Amputations of the index, long, and ring finger were also strongly correlated (weighted Kappa values of 0.68, 0.43, and 0.74) as also a 2 nd metacarpal fracture with a 3 rd metacarpal fracture (weighted Kappa value = 0.60) and a similar dislocation of 2 nd and 3 rd MCP joints (weighted Kappa value = 0.49) [Table 4].
Table 4: McNemar's test results in blast injuries of the hand


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A multivariate analysis was important from a negative aspect with an inference that amputation at the level of the carpal joint on the radial side was unrelated to any other web space injury (B= -2.859, 95% C.I for exp B 0.011-0.299, P = 0.001) and a similar amputation of the thumb was unrelated with any other web space injury (B = -0.993, P = 0.007) [Table 5].
Table 5: Multivariate analysis carpal amputation (Radial) vs other web space injuries


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The most common injury in the patients examined comprised of a pattern of dorsal dislocation of the 1 st metacarpal [Figure 4] with a first web space split associated with varying degrees of injury to the thenar and intrinsic muscles, which was occasionally combined with injuries to the index and long fingers along with their metacarpals. Severe injuries resulted in amputations primarily directed to the radial aspect of the hand. This common pattern of hyperextension and hyperabduction of fingers with amputations in the radial digits has also been outlined by others. [5]
Figure 4: Shows the dorsal dislocation of the 1st metacarpal and disruption of the CMC joint

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In major blasts, there was autoamputation of the whole hand which was noted in 4 patients and 8 patients in total eventually proceeded with a terminalization operation either at the level of the wrist joint or proximal to it because of the extent of the injuries. The management of bony injuries and soft tissue injuries were carried out in a phased manner. In the acute phase, attention was placed to adequate wound excision which was carried out in all patients with serial debridement being carried out in 33 patients. When adequate debridement was possible, wounds could also be closed primarily as was noted in 12 cases with no complications in the postoperative phase [Figure 5]. Dislocation of the carpo-metacarpal (CMC) joint of the thumb was always addressed primarily with K-wire fixation in 38 cases but injuries of the metacarpals was delayed and addressed at the time of soft tissue coverage either using K-wires or with miniplates. A wide range of flaps were used for wound coverage with deepening of the first web space or finger resurfacing with the groin flap being the most common (17 cases) followed closely by the random pattern abdominal flap (8 cases). Other flaps used included the chest flap (4 cases), reverse radial flap (2 cases), and the Posterior Interosseous Artery (PIA) flap (2 cases). No microsurgical procedure was done for finger reconstruction essentially due to lack of education and motivation in our patients. All these patients were managed with intensive post-operative physiotherapy.
Figure 5: Primary repair of moderate type of blast injury after debridement. The dorsal dislocation of the 1st metacarpal has been fixed with a K-wire

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An analysis of the range of motion (ROM) of the fingers revealed that the ROM was closest to normal in patients with mild injuries with a graded deterioration of function as the injuries proceeded from moderate to severe. The length of hospital stay was the shortest in patients with mild injuries but was commonly more than 2 weeks in patients with moderate and severe injuries. Stiffness was especially marked when metacarpal fractures were encountered and was even resistant to intensive physiotherapy. Overall, patients with mild injuries readily regained nearly normal function of the hand while moderate impairment was most common at 3 months in patients with moderate injuries while patients with severe injuries had a propensity to development of severe impairment of hand function at 3 months. Patients with severe injuries could not return to normal occupation because most of them were manual workers while patients with mild injuries readily returned to work while patients with moderate injuries showed a mixed pattern in this regard. The interphalangeal (IP) joint of the thumb was important as amputations proximal to the joint led to a severe impairment of hand function in all patients. [Table 6]
Table 6: Outcome of Blast Injuries of the Hand


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The importance of literacy and adherence to an extensive physiotherapy program needs to be emphasized as patients who complied with an intensive physiotherapy program had a better gain of hand function compared with ignorant, mostly illiterate patients who dropped out from physiotherapy leading to severe impairment of hand function.


   Analysis and Discussion Top


The effects of a blast injury to the hand can be quite complex and has been outlined earlier. However, the possible pathomechanics of a blast injury has not been clearly addressed in the literature although descriptions of injury patterns have been made. [5],[6] Here, we attempt to outline the pathomechanics of a blast injury to the hand and also describe the management protocol as currently practiced in our unit.

The most common pattern of injury comprised of a first web space split with variable degrees of thenar muscle injury, dorsal dislocation of the CMC joint of the thumb, which was occasionally associated with 2 nd and 3 rd metacarpal injuries. In many patients, this was associated with amputations of portions of the 2 nd and 3 rd fingers.

The hand comprises of 4 discrete units of which the thumb is the most mobile owing solely to the mobility of the CMC joint which is bisaddle in nature. [7] The index finger is the next most mobile unit attached to the fixed unit of the hand comprised of the central metacarpals. The rest of the fingers and the metacarpals take part in power grip of the hand.

Our hypothesis regarding the pathomechanics of blast injury to the hand is as follows. For gripping an object like a bomb, the primary action is provided by the thumb and the index finger with a supportive part played by the ulnar fingers while the long finger stabilizes the grip. [8] Therefore, when an explosion occurs with the object being held in the hand or in close contact with the hand, there are several injury vectors acting in a centrifugal direction radiating from the major point of contact with the hand which is the thenar eminence. This is subject to the brunt of the damage by the injury vectors which leads to a first web split.

As the injury vector radiates outside, it next disrupts the loose fitting bisaddle joint of the thumb [9] causing a dorsal dislocation of the same since it has the lowest stability [Figure 6]. The centrifugal injury vectors go on to affect the fingers and also travel to the center of the hand. The MCP joints in the other fingers resist disruption to some extent because the proximally unattached volar plate in these joints permits some degree of hyperextension and shock absorption. [10] The IP joints have fixed volar plates and are therefore unyielding and usually disrupt from the injury leading to amputations of these fingers. The center of the hand comprises of 2 nd and 3 rd metacarpals fixed to the carpus in the hand and their shafts become the weakest target and are subject to fracture from the effect of the blast.
Figure 6: CMC disruption of thumb and dorsal dislocation of 1st metacarpal in a case of blast injury to the hand with fracture of the 3rd metacarpal

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Our hypothesis was reflected in the injury analysis which showed that the radial aspect of the hand was most commonly affected in a case of blast injury to the hand [Table 3]. The injury had the highest proportion in the thumb and the 1 st ray with the center of the hand being affected next and the values tapered off as one moved on to the ulnar side.

McNemar's test showed that there was no significant correlation between thenar muscle injury and 1 st web space injury with a 2 nd web injury, which reflected that the brunt of the injury occurred to the thenar muscles and 1 st web space muscles. MCP dislocations in the 2 nd , 3 rd , and 4 th digits were correlated in a fair number of cases while fractures of the 2 nd metacarpal were strongly correlated with those of the 3 rd metacarpal thereby proving that the injury progressed to the center of the hand in most patients. Injuries of the 1 st , 2 nd , and 3 rd rays were found to be correlated in a fair number of patients with a strong association between injuries to 2 nd and 3 rd rays, which primarily indicated that the thumb along with the center of the hand was affected most commonly from the centrifugal action of the injury vectors.

A multivariate analysis showed that amputations of the thumb and at the level of the carpal joints on the radial aspect of the hand were unrelated to any other web space injuries, which indicated that the major injury vector affects the thumb that may be primarily amputated without affecting the other web spaces in severe injuries.

Revascularization and replantation in the acute setting were not feasible options in our opinion because of the extensive nature of the injuries although it has been recommended. [11] There had been two attempts in our setup with eventual failures. Therefore, our management was based on terminalization operations in the primary and delayed primary settings with adequate wound care and closure. [12] Debridement was mostly carried out in a serial fashion followed by wound coverage. When adequate debridement and repair were possible, many wounds could be closed primarily in the acute setting with no eventual postoperative complications and a near normal range of motion of the involved fingers in the long run even though others feel that the role of primary repair is limited in blast injuries. [5] Joint dislocations were primarily managed with K-wire fixation in the acute setting but Open Reduction and Internal Fixation (ORIF) of bony injuries, primarily metacarpal fractures were delayed until adequate wound coverage was obtained. Fractures of the base of the metacarpals were treated with immobilization, which resulted in an increased degree of stiffness managed with intensive physiotherapy. Minor wounds were healed with secondary intention again with no resultant contractures and near normal range of motion of the affected digits after intensive physiotherapy. No patient in this injury category required any other surgical procedure for stiffness in the rehabilitation phase.

A variety of flaps were used for adequate wound coverage mainly in the delayed primary setting. The groin flap was the most favored in our series and there was good outcome eventually in these patients. The next most common was the random pattern abdominal flap and the chest flap. The posterior interosseous artery and the reverse radial flap were other flaps used in the reconstruction process. [13]

Thumb reconstruction by toe to thumb transfer has been widely recommended but it has not been achieved in the study period owing primarily to the lack of education and motivation in our patients. Of particular importance was the mindset of the patients denying sacrificing a toe for a finger fearing that it would severely impair walking.

Stiffness was marked in our patients in the post-operative phase in those with moderate and severe injuries, which was quite resistant to even intensive physiotherapy programs. The long-term effect of the blast injury on hand function remains to be seen.


   Conclusion Top


Blast injuries of the hand can have a spectrum of effects ranging from a mild injury to amputation of the whole hand. The key to management of blast injuries of the hand is attention towards early debridement and wound coverage with post-operative splinting in the functional position. Stiffness is common after blast injuries and can be countered by a properly instituted range of motion exercise program instituted as early as possible. This might not be possible in hands fixed with K-wires after the injury in whom the compliance of the patient to an intensive physiotherapy program in the post-operative period would ultimately decide the outcome of hand function.


   Acknowledgements Top


I would like to acknowledge the contributions of Prof. Ranabir Pal, Professor of Community Medicine, Sikkim Manipal Institute of Medical Sciences; Dr. Abhijit Hazra, Associate Professor, Department of Pharmacology, IPGMER, Kolkata; and Dr. Adwitiya Das, Post Graduate Trainee, Department of Community Medicine, Institute of Hygiene, Kolkata, in the statistical calculations mentioned in the paper, which has immensely helped me with my work.

 
   References Top

1.Jabaley ME, Peterson HD. Early treatment of war wounds of the hand and forearm in Vietnam. Ann Surg 1973;177:167-73.   Back to cited text no. 1
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2.US Naval Academy. Military explosives. In: Fundamentals of naval weapons systems. Federation of American Scientists website. Available from: http://www.fas.org/man/dod-101/navy/docs/fun/part12.htm. [Last accessed on 2011 Dec 13].  Back to cited text no. 2
    
3.SEC Classification (India). Available from: http://en.wikipedia.org/wiki/SEC_Classification_%28India%29 [Last accessed on 2011 Dec 13].  Back to cited text no. 3
    
4.Kleinert HE, Williams DJ. Blast injuries of the hand. J Trauma 1962;2:10-35.  Back to cited text no. 4
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5.Hazani R, Buntic RF, Brooks D. Patterns in blast injuries to the hand. Hand 2009;4:44-9.   Back to cited text no. 5
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6.Giessler GA, Leopold A, Germann G, Heitmann C. [Blast injuries of the hands. Patterns of trauma and plastic surgical treatment]. Unfallchirurg 2006;109:956-63.  Back to cited text no. 6
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7.Neumann DA, Bielefeld T. The carpometacarpal joint of the thumb: Stability, deformity, and therapeutic intervention. J Orthop Sports Phys Ther 2003;33:386-99.   Back to cited text no. 7
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8.Flatt AE. Grasp. Proc (Bayl Univ Med Cent) 2000;13:343-8.   Back to cited text no. 8
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9.Kauer JM. Functional anatomy of the carpometacarpal joint of the thumb. Clin Orthop Relat Res 1987;220:7-13.   Back to cited text no. 9
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10.Beasley RW. Beasley's Surgery of the Hand. 1 st ed. New York: Thieme; 2003. p. 5-8.   Back to cited text no. 10
    
11.Urbaniak JR. To replant or not to replant? That is not the question [editorial]. J Hand Surg 1983;8(5 Pt 1):507-8.  Back to cited text no. 11
    
12.Logan SE, Bunkis J, Walton RL. Optimum management of hand blast injuries. Int Surg 1990;75:109-14.  Back to cited text no. 12
[PUBMED]    
13.Zancolli EA, Angrigiani C. Posterior interosseous island forearm flap. J Hand Surg 1988;13:130-5.  Back to cited text no. 13
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Correspondence Address:
Souvik Adhikari
Department of Plastic and Reconstructive Surgery, Institute of Post Graduate Medical Education and Research, Kolkata
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/0974-2700.106322

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    Figures

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