620186 research-article2015
JHS0010.1177/1753193415620186Journal of Hand Surgery (European Volume)Alexander et al.
JHS(E)
Full length article
Motorcyclist’s thumb: carpometacarpal injuries of the thumb sustained in motorcycle crashes
The Journal of Hand Surgery (European Volume) XXE(X) 1–3 © The Author(s) 2015 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav DOI: 10.1177/1753193415620186 jhs.sagepub.com
C. Alexander1, J. M. Abzug1, A. J. Johnson1, R. A. Pensy1, W. A. Eglseder1 and E. Paryavi1,2 Abstract The purpose of this study was to investigate motorcycle crash thumb injury patterns. We hypothesized that ulnar collateral ligament injuries at the thumb metacarpophalangeal joint would be most common and there would be a side predilection due to the clutch and brake positions. Motorcyclist admissions following injury between 2002 and 2013 were reviewed, and phalangeal and metacarpal injuries treated acutely identified. Demographics, injury, and treatment characteristics were recorded. Association between laterality and injury type was assessed. Of 128 patients, 59 underwent acute treatment for thumb injuries. Eleven patients sustained thumb ulnar collateral ligament injuries; 27 sustained thumb carpometacarpal injuries. Most carpometacarpal injuries were fracture-dislocations (19/27). Thumb carpometacarpal injuries had no overall side predilection; ulnar collateral ligament injuries occurred more on the right. Carpometacarpal fractures and dislocations are the most frequent motorcycle crash thumb injury, probably due to the mechanics of gripping handlebars and the high-energy force directed into the palm and against the metacarpal base. Level of evidence: Level IV Keywords Thumb carpometacarpal, motorcycle crashes, ulnar collateral ligament Date received: 5th March 2015; revised: 29th September 2015; accepted: 30th September 2015
Introduction According to the National Highway Traffic Safety Administration, in 2012, motorcyclists were five times more likely to be injured in a crash than passenger car occupants (National Highway Traffic Safety Administration, 2014). The Government Accountability Office estimated that in 2010, motorcycle crashes cost the nation 16 billion USdollars in direct costs (US Government Accountability Office, 2012). A total of 18% of those were medical costs, approximately 2.9 billion USdollars (US Government Accountability Office, 2012). Injuries to the hand are common in motorcycle crashes (Schaller and Geldmacher, 1994). However, the incidence and characteristics of traumatic thumb injuries in motorcyclists are not well described. We had observed that ulnar collateral ligament (UCL) tears of the thumb were seen frequently in victims of motorcycle crashes. We hypothesized that UCL injuries at the thumb metacarpophalangeal (MCP) joint would be the most common injury. We also hypothesized that there would be a side predilection for
thumb injuries, favouring the right thumb, due to the clutch and brake position on the left and right handlebars, respectively. The purpose of this study was to investigate the pattern of thumb injuries sustained by motorcyclists and describe the epidemiology and treatment characteristics in our patients.
Methods We performed a retrospective epidemiological study of all thumb injuries following motorcycle crashes that presented to our level I trauma centre
1Department
of Orthopaedics, University of Maryland School of Medicine, Baltimore, MD, USA 2The Curtis National Hand Center, MedStar Union Memorial Hospital, Baltimore, MD, USA Corresponding author: E. Paryavi, c/o Anne Mattson, The Curtis National Hand Center, MedStar Union Memorial Hospital, 3333 North Calvert Street, Mezzanine, Baltimore, MD 21218, USA. Email: [email protected]
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2
The Journal of Hand Surgery (Eur)
between 2002 and 2013. Current procedural terminology (CPT) codes used for billing purposes were searched to identify and categorize these injuries. Institutional Review Board (IRB) approval was obtained and a retrospective review of the medical records for these patients allowed us to record demographic variables, the type and extent of the injury, and the treatment that was employed. Only operatively treated fractures were included as this was the limitation of our database. The coding was performed by the attending surgeon in each case for billing purposes. The records including all hand radiographs for included subjects were reviewed by the first author. Exclusion criteria were any patients who did not sustain a fracture or dislocation of the thumb from the carpometacarpal joint to the distal phalanx. Analysis of our data was mainly exploratory and descriptive, calculating and reporting of median and interquartile ranges for continuous variables and frequencies for categorical variables. We then examined side predilection for carpometacarpal (CMC) and UCL injuries compared with all other injuries using a Fisher’s exact test. Alpha for significance was set to 0.05 and all P-values were calculated in a two-tailed fashion.
Results A total of 128 out of 2152 motorcyclists underwent operative treatment of an injury to the digits of the hand following a motorcycle crash in the time period between 2002 and 2013. Of those, 59 (46%) had an injury to the thumb. Of the thumb injuries, the most common location was the thumb CMC joint in 27 patients (46%). By contrast, only 12 patients (20%) sustained a thumb UCL injury. Other digital injuries consisted of phalangeal fractures (14%), interphalangeal dislocations (3.4%) and metacarpal fractures (49%). Open injuries were seen in 11 patients (19%). The mean age of patients sustaining a thumb injury was 38 years (range 28–48) (Table 1). Several patients sustained more than one injury, accounting for the larger number of injuries compared with patients. Thumb CMC joint injuries sustained were mostly fracture-dislocations (19/27). Pure ligamentous injury was less common (8/27). Of the 19 CMC fracture-dislocations, 18 were fractures to the metacarpal base, whereas fracture of the trapezium was found in only one patient. Open reduction was performed in 21 of 27 CMC injuries, 19 of which included a dorsal approach. Repair of the dorsoradial ligament and associated dorsal ligamentous structures was performed in six patients and reconstruction was performed in three patients. Acute repair of the palmar oblique ligament was performed in one patient; three patients underwent
Table 1. Demographics all injuries. %
n = 59 Age (IQR) Side Right Left Open Injury Gamekeeper’s CMC dislocation CMC fracture/dislocation Phalangeal fracture IP fracture MC fracture Stener lesion among gamekeepers Distal UCL avulsion
38 (28–48) 31 28 11 12 8 19 8 2 29 9 12
53 48 19 20 14 32 14 3.4 49
CMC: carpometacarpal; IP: interphalangeal; IQR: interquartile range; MC: metacarpal; UCL: ulnar collateral ligament.
Table 2. Side predilection for CMC and gamekeeper’s injuries.
Side Side
n = Right Left n = Right Left
CMC
Other
P =
27 13 14 Gamekeeper’s 12 10 2
32 18 14 Other 47 21 26
0.61 P = 0.023
CMC: carpometacarpal.
reconstruction. These three patients also had dorsoradial ligament reconstruction. There was no side predilection in these patients, as 13 patients sustained CMC injury to the right thumb and 14 to the left thumb (P = 0.61) (Table 2). All 12 thumb MCP joint UCL injuries occurred as distal UCL avulsion injuries from the base of the proximal phalanx. There was a Stener lesion in nine patients. Unlike CMC joint injuries, there was an observed side predilection of UCL injuries in our patient population, with 10 (83%) occurring on the right and only two occurring on the left (Table 2). A UCL injury was associated with an ipsilateral CMC joint dislocation in one patient. Only one patient sustained an open UCL injury presenting as an MCP joint dislocation.
Discussion Injuries to the thumb accounted for 46% of all injuries to digits undergoing acute treatment in this study of patients who suffered a motorcycle crash. The exposure
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3
Alexander et al. of the hand in motorcycle crashes and the thumb’s position of opposition in a grip on the handlebars make it uniquely predisposed to injury. We hypothesized that UCL injuries would be the most common based on an anecdotal observation that these injuries were occurring frequently in this population. However, our results showed that CMC injuries are, in fact, the most frequently sustained. We believe that the high-energy force vectors, directed into the first webspace from the handlebars at the time of the crash, are responsible for the large percentage of CMC joint injuries as compared with UCL injuries that are caused from angular forces to the MCP joint. Although this mechanism was proposed by Johnson et al. (1987) to explain dislocations of the CMC joint, we found that fracture-dislocations of the thumb metacarpal base were far more common than pure ligamentous injury. Although thumb UCL injuries were not the most frequent injury, there was a side predilection in these patients favouring the right side. Because the brake is located on the right side of the handlebars, this may represent the instinct to grasp the brake hard with the right hand immediately before and during the crash. This difference was seen in UCL injuries but not CMC joint injuries, which may represent a different force vector responsible for these injuries. In higher energy collisions, the rider may instinctively grasp both handlebars with equal force resulting in injury by the direct blow to the thenar eminence or at the base of the thumb metacarpal from the handlebars. Conversely, slower speed crashes may result in forceful abduction of the thumb at the MCP joint, accentuated by a preferential hard grasp on the brake alone, thereby causing a classic UCL injury. The UCL injuries sustained in our series had features consistent with the descriptions in prior literature (Gerber et al., 1981; Harding and McKeag, 1995). Stener lesions were found in the majority of these injuries. All injuries occurred at the distal portion of the UCL, either in the ligamentous portion just proximal to the insertion or as a distal avulsion fracture from the base of the proximal phalanx. Whether all of these injuries would have been treated surgically by all surgeons is also open to debate (Giddins, 2015). There are several limitations to the present study. As an observational, retrospective epidemiological study, there were no outcomes measured. Our decision and techniques for operative treatment are based on the personal experience of the senior surgeons, which may vary from practices at other institutions. This study may also have lacked power to detect a true difference in the sidedness of CMC injuries and a real difference may still exist. Our data
were collected using current procedural terminology codes from an institutional billing system and other data were obtained from a trauma registry. This may overestimate the frequency of more severe injuries, like CMC fracture dislocations requiring treatment, and underestimate purely ligamentous injuries, like CMC dislocations, which may not present initially because of lack of radiographic findings and distracting injuries in motorcycle crash victims who often have multiple injuries. Because many of these injuries are missed due to distracting injuries and subtle examination findings, some of these patients may have presented to hand specialists outside of our trauma centre where they received their initial care. Carpometacarpal fractures and dislocations are the most frequent motorcycle crash thumb injury, probably due to the mechanics of gripping handlebars and the high-energy force directed into the palm and against the metacarpal base. Declaration of conflicting interests The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
Ethical approval The research protocol for this study was approved by the University of Maryland School of Medicine Institutional Review Board.
Funding The authors received no financial support for the research, authorship, and/or publication of this article. Anne Mattson, an employee of The Curtis National Hand Center, provided editorial assistance.
References Gerber C, Senn E, Matter P. Skier’s thumb. Surgical treatment of recent injuries to the ulnar collateral ligament of the thumb’s metacarpophalangeal joint. Am J Sports Med. 1981, 9: 171–7. Giddins GE. The non-operative management of hand fractures. J Hand Surg Eur. 2015, 40: 33–41. Harding P, McKeag L. Skier’s thumb: a literature review. Aust J Physiother. 1995, 41: 29–33. Johnson SR, Jones DG, Hoddinott HC. Missed carpometacarpal dislocation of the thumb in motorcyclists. Injury. 1987, 18: 415–6. National Highway Traffic Safety Administration, US Department of Transportation. Traffic Safety Facts 2012 Data. DOT HS 812 035, 1–8. 2014. Washington DC, NHTSA’s National Center for Statistics and Analysis. Schaller P, Geldmacher J. [Hand injury in polytrauma. A retrospective study of 782 cases]. Handchir Mikrochir Plast Chir. 1994, 26: 307–12. US Government Accountability Office. Motorcycle Safety: Increasing Federal Funding Flexibility and Indentifying Research Priorities Would Help Support States’ Safety Efforts. GAO-13–42, 1–61. 2012. Washington DC.
Downloaded from jhs.sagepub.com at UNIV CALIFORNIA SAN DIEGO on February 8, 2016
JHS0010.1177/1753193415620186Journal of Hand Surgery (European Volume)Alexander et al.
JHS(E)
Full length article
Motorcyclist’s thumb: carpometacarpal injuries of the thumb sustained in motorcycle crashes
The Journal of Hand Surgery (European Volume) XXE(X) 1–3 © The Author(s) 2015 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav DOI: 10.1177/1753193415620186 jhs.sagepub.com
C. Alexander1, J. M. Abzug1, A. J. Johnson1, R. A. Pensy1, W. A. Eglseder1 and E. Paryavi1,2 Abstract The purpose of this study was to investigate motorcycle crash thumb injury patterns. We hypothesized that ulnar collateral ligament injuries at the thumb metacarpophalangeal joint would be most common and there would be a side predilection due to the clutch and brake positions. Motorcyclist admissions following injury between 2002 and 2013 were reviewed, and phalangeal and metacarpal injuries treated acutely identified. Demographics, injury, and treatment characteristics were recorded. Association between laterality and injury type was assessed. Of 128 patients, 59 underwent acute treatment for thumb injuries. Eleven patients sustained thumb ulnar collateral ligament injuries; 27 sustained thumb carpometacarpal injuries. Most carpometacarpal injuries were fracture-dislocations (19/27). Thumb carpometacarpal injuries had no overall side predilection; ulnar collateral ligament injuries occurred more on the right. Carpometacarpal fractures and dislocations are the most frequent motorcycle crash thumb injury, probably due to the mechanics of gripping handlebars and the high-energy force directed into the palm and against the metacarpal base. Level of evidence: Level IV Keywords Thumb carpometacarpal, motorcycle crashes, ulnar collateral ligament Date received: 5th March 2015; revised: 29th September 2015; accepted: 30th September 2015
Introduction According to the National Highway Traffic Safety Administration, in 2012, motorcyclists were five times more likely to be injured in a crash than passenger car occupants (National Highway Traffic Safety Administration, 2014). The Government Accountability Office estimated that in 2010, motorcycle crashes cost the nation 16 billion USdollars in direct costs (US Government Accountability Office, 2012). A total of 18% of those were medical costs, approximately 2.9 billion USdollars (US Government Accountability Office, 2012). Injuries to the hand are common in motorcycle crashes (Schaller and Geldmacher, 1994). However, the incidence and characteristics of traumatic thumb injuries in motorcyclists are not well described. We had observed that ulnar collateral ligament (UCL) tears of the thumb were seen frequently in victims of motorcycle crashes. We hypothesized that UCL injuries at the thumb metacarpophalangeal (MCP) joint would be the most common injury. We also hypothesized that there would be a side predilection for
thumb injuries, favouring the right thumb, due to the clutch and brake position on the left and right handlebars, respectively. The purpose of this study was to investigate the pattern of thumb injuries sustained by motorcyclists and describe the epidemiology and treatment characteristics in our patients.
Methods We performed a retrospective epidemiological study of all thumb injuries following motorcycle crashes that presented to our level I trauma centre
1Department
of Orthopaedics, University of Maryland School of Medicine, Baltimore, MD, USA 2The Curtis National Hand Center, MedStar Union Memorial Hospital, Baltimore, MD, USA Corresponding author: E. Paryavi, c/o Anne Mattson, The Curtis National Hand Center, MedStar Union Memorial Hospital, 3333 North Calvert Street, Mezzanine, Baltimore, MD 21218, USA. Email: [email protected]
Downloaded from jhs.sagepub.com at UNIV CALIFORNIA SAN DIEGO on February 8, 2016
2
The Journal of Hand Surgery (Eur)
between 2002 and 2013. Current procedural terminology (CPT) codes used for billing purposes were searched to identify and categorize these injuries. Institutional Review Board (IRB) approval was obtained and a retrospective review of the medical records for these patients allowed us to record demographic variables, the type and extent of the injury, and the treatment that was employed. Only operatively treated fractures were included as this was the limitation of our database. The coding was performed by the attending surgeon in each case for billing purposes. The records including all hand radiographs for included subjects were reviewed by the first author. Exclusion criteria were any patients who did not sustain a fracture or dislocation of the thumb from the carpometacarpal joint to the distal phalanx. Analysis of our data was mainly exploratory and descriptive, calculating and reporting of median and interquartile ranges for continuous variables and frequencies for categorical variables. We then examined side predilection for carpometacarpal (CMC) and UCL injuries compared with all other injuries using a Fisher’s exact test. Alpha for significance was set to 0.05 and all P-values were calculated in a two-tailed fashion.
Results A total of 128 out of 2152 motorcyclists underwent operative treatment of an injury to the digits of the hand following a motorcycle crash in the time period between 2002 and 2013. Of those, 59 (46%) had an injury to the thumb. Of the thumb injuries, the most common location was the thumb CMC joint in 27 patients (46%). By contrast, only 12 patients (20%) sustained a thumb UCL injury. Other digital injuries consisted of phalangeal fractures (14%), interphalangeal dislocations (3.4%) and metacarpal fractures (49%). Open injuries were seen in 11 patients (19%). The mean age of patients sustaining a thumb injury was 38 years (range 28–48) (Table 1). Several patients sustained more than one injury, accounting for the larger number of injuries compared with patients. Thumb CMC joint injuries sustained were mostly fracture-dislocations (19/27). Pure ligamentous injury was less common (8/27). Of the 19 CMC fracture-dislocations, 18 were fractures to the metacarpal base, whereas fracture of the trapezium was found in only one patient. Open reduction was performed in 21 of 27 CMC injuries, 19 of which included a dorsal approach. Repair of the dorsoradial ligament and associated dorsal ligamentous structures was performed in six patients and reconstruction was performed in three patients. Acute repair of the palmar oblique ligament was performed in one patient; three patients underwent
Table 1. Demographics all injuries. %
n = 59 Age (IQR) Side Right Left Open Injury Gamekeeper’s CMC dislocation CMC fracture/dislocation Phalangeal fracture IP fracture MC fracture Stener lesion among gamekeepers Distal UCL avulsion
38 (28–48) 31 28 11 12 8 19 8 2 29 9 12
53 48 19 20 14 32 14 3.4 49
CMC: carpometacarpal; IP: interphalangeal; IQR: interquartile range; MC: metacarpal; UCL: ulnar collateral ligament.
Table 2. Side predilection for CMC and gamekeeper’s injuries.
Side Side
n = Right Left n = Right Left
CMC
Other
P =
27 13 14 Gamekeeper’s 12 10 2
32 18 14 Other 47 21 26
0.61 P = 0.023
CMC: carpometacarpal.
reconstruction. These three patients also had dorsoradial ligament reconstruction. There was no side predilection in these patients, as 13 patients sustained CMC injury to the right thumb and 14 to the left thumb (P = 0.61) (Table 2). All 12 thumb MCP joint UCL injuries occurred as distal UCL avulsion injuries from the base of the proximal phalanx. There was a Stener lesion in nine patients. Unlike CMC joint injuries, there was an observed side predilection of UCL injuries in our patient population, with 10 (83%) occurring on the right and only two occurring on the left (Table 2). A UCL injury was associated with an ipsilateral CMC joint dislocation in one patient. Only one patient sustained an open UCL injury presenting as an MCP joint dislocation.
Discussion Injuries to the thumb accounted for 46% of all injuries to digits undergoing acute treatment in this study of patients who suffered a motorcycle crash. The exposure
Downloaded from jhs.sagepub.com at UNIV CALIFORNIA SAN DIEGO on February 8, 2016
3
Alexander et al. of the hand in motorcycle crashes and the thumb’s position of opposition in a grip on the handlebars make it uniquely predisposed to injury. We hypothesized that UCL injuries would be the most common based on an anecdotal observation that these injuries were occurring frequently in this population. However, our results showed that CMC injuries are, in fact, the most frequently sustained. We believe that the high-energy force vectors, directed into the first webspace from the handlebars at the time of the crash, are responsible for the large percentage of CMC joint injuries as compared with UCL injuries that are caused from angular forces to the MCP joint. Although this mechanism was proposed by Johnson et al. (1987) to explain dislocations of the CMC joint, we found that fracture-dislocations of the thumb metacarpal base were far more common than pure ligamentous injury. Although thumb UCL injuries were not the most frequent injury, there was a side predilection in these patients favouring the right side. Because the brake is located on the right side of the handlebars, this may represent the instinct to grasp the brake hard with the right hand immediately before and during the crash. This difference was seen in UCL injuries but not CMC joint injuries, which may represent a different force vector responsible for these injuries. In higher energy collisions, the rider may instinctively grasp both handlebars with equal force resulting in injury by the direct blow to the thenar eminence or at the base of the thumb metacarpal from the handlebars. Conversely, slower speed crashes may result in forceful abduction of the thumb at the MCP joint, accentuated by a preferential hard grasp on the brake alone, thereby causing a classic UCL injury. The UCL injuries sustained in our series had features consistent with the descriptions in prior literature (Gerber et al., 1981; Harding and McKeag, 1995). Stener lesions were found in the majority of these injuries. All injuries occurred at the distal portion of the UCL, either in the ligamentous portion just proximal to the insertion or as a distal avulsion fracture from the base of the proximal phalanx. Whether all of these injuries would have been treated surgically by all surgeons is also open to debate (Giddins, 2015). There are several limitations to the present study. As an observational, retrospective epidemiological study, there were no outcomes measured. Our decision and techniques for operative treatment are based on the personal experience of the senior surgeons, which may vary from practices at other institutions. This study may also have lacked power to detect a true difference in the sidedness of CMC injuries and a real difference may still exist. Our data
were collected using current procedural terminology codes from an institutional billing system and other data were obtained from a trauma registry. This may overestimate the frequency of more severe injuries, like CMC fracture dislocations requiring treatment, and underestimate purely ligamentous injuries, like CMC dislocations, which may not present initially because of lack of radiographic findings and distracting injuries in motorcycle crash victims who often have multiple injuries. Because many of these injuries are missed due to distracting injuries and subtle examination findings, some of these patients may have presented to hand specialists outside of our trauma centre where they received their initial care. Carpometacarpal fractures and dislocations are the most frequent motorcycle crash thumb injury, probably due to the mechanics of gripping handlebars and the high-energy force directed into the palm and against the metacarpal base. Declaration of conflicting interests The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
Ethical approval The research protocol for this study was approved by the University of Maryland School of Medicine Institutional Review Board.
Funding The authors received no financial support for the research, authorship, and/or publication of this article. Anne Mattson, an employee of The Curtis National Hand Center, provided editorial assistance.
References Gerber C, Senn E, Matter P. Skier’s thumb. Surgical treatment of recent injuries to the ulnar collateral ligament of the thumb’s metacarpophalangeal joint. Am J Sports Med. 1981, 9: 171–7. Giddins GE. The non-operative management of hand fractures. J Hand Surg Eur. 2015, 40: 33–41. Harding P, McKeag L. Skier’s thumb: a literature review. Aust J Physiother. 1995, 41: 29–33. Johnson SR, Jones DG, Hoddinott HC. Missed carpometacarpal dislocation of the thumb in motorcyclists. Injury. 1987, 18: 415–6. National Highway Traffic Safety Administration, US Department of Transportation. Traffic Safety Facts 2012 Data. DOT HS 812 035, 1–8. 2014. Washington DC, NHTSA’s National Center for Statistics and Analysis. Schaller P, Geldmacher J. [Hand injury in polytrauma. A retrospective study of 782 cases]. Handchir Mikrochir Plast Chir. 1994, 26: 307–12. US Government Accountability Office. Motorcycle Safety: Increasing Federal Funding Flexibility and Indentifying Research Priorities Would Help Support States’ Safety Efforts. GAO-13–42, 1–61. 2012. Washington DC.
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