Epidemiology and Impact of Hand and Wrist Injuries in Major and Minor League Baseball

Abstract

Background: Professional baseball players are at risk of acute and chronic injuries to their upper extremities. Methods: Major League Baseball’s Health and Injury Tracking System, a prospective injury surveillance system, was used to identify and characterize all hand and wrist injuries sustained by all Major League Baseball (MLB) and Minor League Baseball (MiLB) players during the pre-, regular, and postseason throughout 2011-2016. Injuries were included if they resulted in at least 1 day out of play and were sustained during standard baseball activities. Days missed were defined as the time between injury and the first time in which a player was cleared to return to play. Results: During the study period, there were 4478 hand and 1748 wrist injuries throughout MLB and MiLB, which resulted in a total of 105 246 days out of play. This was equivalent to the length of 575 individual MLB player seasons, and the mean days missed per injury was 17 days. Most injuries were traumatic in nature, with 43% (n = 2672) of players injured after being hit by a baseball that mainly occurred during batting (n = 2521; 40%). Injuries that most frequently required surgical intervention were hook of hamate fractures (72%) and scaphoid fractures (60%). Conclusions: Understanding the epidemiology and impact of hand and wrist injuries in MLB and MiLB players may lead to improved management of these injuries and reduce time away from play. Most importantly, preventive measures and/or enhanced protective gear may be developed to minimize these types of injuries in MLB and MiLB.

Introduction

Professional baseball players are at risk of acute and chronic injuries to their upper extremities, which can result in numerous days away from play.^1,2 Throughout 11 seasons of Major League Baseball (MLB), Conte et al ³ noted that more than 3282 players were placed on the disabled list (DL) for a duration of nearly 195 671 total DL days. More worrisome is the fact that they observed an increasing total number of newly designated DL players each year of their study period, with nearly 56% of cases attributed to an upper extremity injury. ³ Dahm et al ⁴ reported that among MLB and Minor League Baseball (MiLB) players, an injury to the upper extremity (from the clavicle to the fingertip) occurred in 34% of players during the 2011-2014 seasons. However, the characteristics of the upper extremity injuries were not reported.

Several sports injury surveillance systems have been developed to record injury trends and to hopefully guide injury prevention measures. ⁵ For example, the National Collegiate Athletic Association’s Injury Surveillance Program collects injury and athlete exposure data from a sample of collegiate institutions in various sports. ⁶ The information from this database was paramount in directing policy change in ice hockey and football to reduce injuries. ⁶ Major League Baseball formerly used the DL for surveillance purposes that inherently had many limitations, such as the need for greater than 14 days missed from play to be included on the DL, exclusion of MiLB players, and lack of specific diagnoses and treatment strategies. Furthermore, using only players who had an injury severity that warranted placement on the DL does not capture all injuries and is subject to nonmedical factors that are weighed into the decision to place a player onto the DL.^1-3,5,7 Nonetheless, information obtained from evaluating MLB’s DL can play a role in injury prevention. For example, in 2016, MLB and the MLB Players Association adopted a rule modification to reduce the number of intentional collisions while sliding into second base to break up a double play. ⁸

Due to a greater emphasis on injury surveillance and prevention, MLB developed and implemented the Health and Injury Tracking System (HITS) in 2011. ⁵ This centralized database contains de-identified medical data from the MLB electronic medical record (EMR) system and is linked to MLB’s electronic Baseball Information System, which is connected to all 30 Major League clubs including their Minor League affiliates. ⁵ Any player who sustains an injury that requires at least 1 day away from play is entered into the HITS database by the club’s athletic trainer (AT) to document all injuries sustained by MLB and MiLB players.

As of 2017, the HITS database has been used to report the epidemiology of knee and elbow injuries in MLB and MiLB players, yet none have focused on the hand and/or wrist.^4,9 The purpose of this study was to describe the characteristics and impact of hand and wrist injuries occurring in MLB and MiLB during the 2011-2016 seasons by using a comprehensive injury surveillance system developed by MLB.

Methods

After approval had been obtained from the institutional review board, MLB’s HITS was used to identify all MLB and MiLB players with hand and wrist injuries during the 2011-2016 seasons. Injuries were included if they occurred during the pre-, regular, or postseason; resulted in at least 1 day out of play; and were sustained during standard baseball activities such as training, conditioning, and practice or during live game play. All data were extracted and analyzed in an anonymous and de-identified fashion. A number of patient-specific variables were analyzed, including age, position, and level of play (MLB vs MiLB). Injury-specific variables that were analyzed included: injury date, days missed, activity that resulted in injury (batting, fielding, throwing, etc.), injury mechanism, body region (wrist vs hand), laterality, diagnosis, and need for surgery.

Days missed were defined as the time between injury and the first time in which a player was cleared to return to play. Trends in injury volume and days missed were analyzed over time. Comparisons were made between players based on level of play (MLB vs MiLB) and between injuries based on body region (wrist vs hand). Separate and distinct rank order lists were compiled for the most common hand injuries, wrist injuries, and surgical procedures performed.

Statistical Analysis

Descriptive statistics were used to report epidemiologic findings such as numbers, frequencies, means, standard deviations (SD), and medians. Pairwise comparisons between means of normally distributed variables were made using a Student t test. Differences in proportions (frequency of surgery for MLB vs MiLB players) were analyzed using Fisher exact test. Linear regression was used to assess the significance of trends over time, and these results are reported with their corresponding R² and P values. Only values of P < .05 were considered to represent statistical significance.

Results

During the 2011-2016 seasons, a total of 6226 hand and wrist injuries resulted in time out of play from professional baseball (Table 1). Of these, 902 (14%) occurred in MLB players, whereas 5324 (86%) occurred in MiLB players. These injuries resulted in a total of 105 246 days out of play, which is equivalent to the length of 575 individual MLB player seasons. Mean days missed per injury was 17, but the median was much lower at 5 days. Further analysis of these injuries by body region (hand vs wrist) is provided in Table 1.

Table 1.

Demographics of Hand and Wrist Injuries in Major and Minor League Baseball.

Major vs. Minor League Injuries	Major league	Minor league	Overall	P value
No. of injuries (%)	902 (14)	5324 (86)	6226 (100)
Total number of days missed a	17 788	87 458	105 246
Mean (median) number of days missed per injury a	20.0 (32.6)	16.9 (28.6)	17.3 (5)	.004
Frequency of surgery, %	9.2	6.7	7.1	.009
Hand/finger vs. Wrist Injuries	Hand/fingers	Wrist		P value
No. of injuries (%)	4478 (72)	1748 (28)
Total number of days missed a	67 036	38 210
Mean (median) number of days missed per injury a	15.2 (4)	22.8 (34.1)		.001
Frequency of surgery, %	4.5	13.7		< .001

Note. Significant P values (<.05) are in bold.

^aSeason-ending injuries not included in days missed.

When looking at trends over time, there was no significant change in the annual number of MLB (R² = 0.072; P = .608), MiLB (R² = .302; P = 0.258), or total injuries (R² = 0.193; P = 0.384) from 2011 to 2016 (Supplemental Figure 1). Similarly, the number of hand (R² = 0.281; P = .280) and wrist (R² = 0.024; P = .770) injuries remained steady during the study period (Supplemental Figure 2).

The most common injury mechanism was traumatic in nature, with 2672 players (43%) missing time after being hit by a baseball. The remaining injury mechanisms are detailed in Table 2. Most injuries occurred while the players were either batting (n = 2521; 40%) or fielding (n = 1839; 30%) (Table 2).

Table 2.

Most Common Injury Mechanisms and Activities.

	No. (%)
Injury mechanism
Contact with ball	2672 (43)
Noncontact	1376 (22)
Contact with ground	1051 (17)
Contact with person	391 (6)
Contact with bat	382 (6)
Contact with boundary/wall	68 (1)
Other/unknown	286 (5)
Injury activity
Batting	2521 (40)
Fielding	1839 (30)
Pitching	818 (13)
Sliding	706 (11)
Throwing	170 (3)
Base running	106 (2)
Other/unknown	61 (1)
Conditioning/weight training	3 (<1)
Coaching	2 (<1)

Infield was the most commonly injured position for both hand (32%) and wrist injuries (41%) (Figure 1).

Figure 1.

Distribution of injuries based on player position.

A detailed breakdown of injury types is provided in Figure 2. Looking specifically at hand injuries, contusions (n = 1898; 42.4%), blisters (n = 401; 9.0%), thumb ulnar collateral ligament (UCL) injuries (n = 332; 7.4%), metacarpal fractures (n = 212; 4.7%), and finger proximal interphalangeal joint sprains (n = 211; 4.7%) were the most common (Table 3). The hand injuries that most commonly required surgery were finger proximal phalanx fractures (34.8%), thumb phalangeal fractures (22.5%), and thumb UCL injury (17.5%). For the wrist, the most common injuries were wrist sprains (n = 589; 33.7%), wrist contusions (n = 443; 25.3%), hook of hamate fractures (n = 185; 10.6%), wrist extensor tendinopathy (n = 84; 4.8%), and triangular fibrocartilage complex (TFCC) tears (n = 56; 3.2%) (Table 4). Players diagnosed with a hook of hamate fracture required surgery in 72.4% of cases. The most common surgical procedures are listed in Table 5, with hook of hamate excision (38.2%) and thumb UCL repair (10%) being the most frequent.

Figure 2.

Distribution of injuries types based on anatomical location.

Table 3.

Most Common Diagnoses for Hand/Finger Injuries in Professional Baseball Players.

Hand/finger injury diagnosis	Overall		Total days missed a	Mean days missed a	Frequency of surgery,%
	No. (%)	Rank
Hand contusion	1898 (42.4)	1	14 997	8.0	1.3
Blister	401 (9.0)	2	2946	7.3	0.0
Other hand injury	399 (8.9)	3	5871	15.2	5.7
Thumb—ulnar collateral ligament sprain or rupture	332 (7.4)	4	8182	25.6	17.5
Metacarpal fracture	212 (4.7)	5	11 801	59.6	16.5
Finger proximal interphalangeal joint sprain	211 (4.7)	6	2383	11.6	2.4
Hand laceration	163 (3.6)	7	1445	8.9	0.6
Nail avulsion	130 (2.9)	8	665	5.1	0.0
Other metacarpophalangeal joint sprain	116 (2.6)	9	1599	14.0	1.7
Distal phalyngeal fracture of fingers	92 (2.1)	10	3069	33.7	6.5
Finger distal interphalangeal joint sprain	83 (1.9)	11	1147	14.0	0.0
Intrinsic muscle strain	83 (1.9)	12	1503	18.6	1.2
Thumb phalanx fracture	71 (1.6)	13	3018	43.7	22.5
Finger proximal interphalangeal joint dislocation	56 (1.3)	14	1066	19.7	7.1
Proximal phalangeal fracture of fingers	46 (1.0)	15	2704	61.5	34.8
Finger tenosynovitis	32 (0.7)	16	690	23.8	6.3
Subungal hematoma	31 (0.7)	17	455	14.7	3.2
Middle phalangeal fracture of fingers	27 (0.6)	18	1123	44.9	14.8
Finger distal interphalangeal joint dislocation	23 (0.5)	19	333	14.5	0.0
Hand abrasion	22 (0.5)	20	182	8.3	4.5
Thumb interphalangeal joint dislocation	19 (0.4)	21	607	31.9	5.3

Note. Only diagnoses with at least 10 occurrences are included in this analysis.

^aDays missed calculations do not include season-ending injuries.

Table 4.

Most Common Diagnoses for Wrist Injuries in Professional Baseball Players.

Wrist injury diagnosis	Overall		Total days missed a	Mean days missed a	Frequency of surgery, %
	No. (%)	Rank
Wrist sprain	589 (33.7)	1	9558	16.9	4.2
Wrist contusion	443 (25.3)	2	3751	8.7	1.6
Hook of hamate fracture	185 (10.6)	3	9365	51.5	72.4
Other wrist injury	171 (9.8)	4	4679	29.2	9.9
Wrist extensor tendinopathy	84 (4.8)	5	1962	24.8	9.5
Triangular fibrocartilage complex tear	56 (3.2)	6	2635	47.9	32.1
Wrist flexor tendinopathy	45 (2.6)	7	1072	24.4	8.9
Wrist extensor tenosynovitis	36 (2.1)	8	824	23.5	2.8
Wrist impingement	27 (1.5)	9	473	18.9	14.8
Pisiform fracture	16 (0.9)	10	743	49.5	12.5
Extensor carpi ulnaris subluxation	13 (0.7)	11	454	41.3	46.2
Scaphoid fracture	10 (0.6)	12	588	73.5	60.0
Scapholunate instability	10 (0.6)	13	290	32.2	20.0

Note. Only diagnoses with at least 10 occurrences are included in this analysis.

^aDays missed calculations do not include season-ending injuries.

Table 5.

Most Common Surgical Procedures Performed for Hand and Wrist Injuries.

Surgical procedures	Overall
	No. (%)	Rank
Hook of hamate excision	224 (32.8)	1
Thumb UCL repair	68 (10.0)	2
Finger metacarpal ORIF	40 (5.9)	3
TFCC repair	26 (3.8)	4
Finger metacarpal CRPP	24 (3.5)	5
Guyon’s canal release	23 (3.4)	6
Scaphoid ORIF	15 (2.2)	7
Thumb phalanx CRPP	14 (2.1)	t-8
Finger phalanx CRPP	14 (2.1)	t-8
Carpal tunnel release	12 (1.8)	t-10
Extensor carpi ulnaris stabilization	12 (1.8)	t-10
TFCC debridement	10 (1.5)	12
Finger phalanx ORIF	9 (1.3)	13
Dorsal compartment reconstruction	5 (0.7)	14
Finger felon irrigation and debridement	4 (0.6)	t-15
Thumb phalanx ORIF	4 (0.6)	t-15
Bennet fracture CRPP	4 (0.6)	t-15
Volar wrist ganglion cyst excision	4 (0.6)	t-15

Note. Only surgeries with at least 4 occurrences are included in this analysis. t = tied; UCL = ulnar collateral ligament; ORIF = open reduction internal fixation; TFCC = triangular fibrocartilage complex; CRPP = closed reduction percutaneous pinning.

Discussion

Based on MLB’s HITS, injuries to the hand and wrist are common in MLB and MiLB players and can result in prolonged time out of play. Ultimately, 4478 hand and 1748 wrist injuries were responsible for 105 246 missed days (the equivalent of 575 individual MLB player seasons). Most injuries were traumatic in nature, and the most common injury activity was batting. Surgery was required in 7.1% of cases, and the most common diagnoses requiring surgical interventions were hamate (72% surgical rate) and scaphoid (60% surgical rate) fractures.

Initially implemented in 2011 for injury surveillance, HITS has been used in multiple epidemiologic studies to focus on injuries to various focused musculoskeletal regions.^4,9 Dahm et al ⁴ reported on 2171 knee injuries in MLB and MiLB players during the 2011-2014 seasons, with a mean days missed due to injury of 16 days and 12% (n = 263) of players requiring surgery. During the same surveillance period, Ciccotti et al ⁹ observed 3185 elbow injuries in MLB and MiLB players, with a mean of 27 days missed per injury and 20% (n = 650) of players requiring surgery. At the end of the 2014 season, HITS noted a prevalence of 3409 (10%) hand, finger, or thumb injuries and 1384 (4.1%) wrist injuries out of 33 623 total injuries to various regions throughout the body since 2010 in MLB and MiLB players.^4,9

Injuries to the upper extremity, particularly the hand and wrist, are common in elite baseball players. McFarland and Wasik ¹⁰ performed a prospective study of a single Division 1 collegiate baseball program over 3 seasons to identify the number of injuries sustained during the study period. They noted that injuries to the upper extremity accounted for 51% of 277 orthopedic complaints, with 17% (n = 24) occurring in the wrist, hand, fingers, and thumb. Posner et al ² used MLB DL data from 2002 to 2008 and observed more injuries to the upper extremity (51%) compared with the lower extremity (31%). They reported that hand and wrist injuries accounted for 10% of all injuries per season, which resulted in a player being placed on the DL. Similarly, Li et al ¹ noted that during the 2008-2009 season of a single MLB organization, 45% of players were placed on the DL due to an upper extremity injury (n = 60), of which 28% (n = 17) were a result of an injury to the wrist.

Injuries to the hand and wrist can result in a prolonged period away from participation in MLB and MiLB players. Li et al ¹ reported that the mean days missed per wrist injury in 17 patients placed on the DL within a single MLB organization was 16 days. This is in contrast to a mean of 27.2 and 16.2 days missed per elbow or knee injury in all MLB and MiLB players, respectively.^4,9 In the current study, the mean days missed per injury, while excluding season-ending injuries, was 22.8 days for wrist injuries and 15.2 days for hand injuries in all MLB and MiLB players. The greater number of days away from participation for a wrist injury may be due to the fact that nearly 13.7% of wrist injuries required surgical intervention compared with 4.5% of hand injuries, the former resulting in prolonged postoperative immobilization and rehabilitation.

Contrary to other upper extremity injuries sustained in MLB and MiLB players that occur secondary to overuse, hand and wrist injuries are mostly due to contact-related traumatic mechanisms. Specifically within the elbow, Ciccotti et al ⁹ noted that 84.9% (786 of 905) of ligament injuries involved the UCL, 67.2% (92 of 137) of bone injuries were due to posteromedial impingement, and 46.3% (260 of 562) of tendon injuries involved the flexor-pronator mass in MLB and MiLB players. However, 40% of these injuries were in pitchers, and the most common mechanism was noncontact. In other words, in their series, elbow injuries are typically atraumatic in nature and secondary to overuse. The current study noted that 72% of hand and wrist injuries in MLB and MiLB players were secondary to contact with a ball (43%), ground (17%), person (6%), or bat (6%) that occurred most commonly while batting (40%) or fielding (30%), whereas only 22% of hand and wrist injuries were attributed to nontraumatic mechanisms.

In MLB and MiLB players, fractures to the hand can result in tremendous time away from participation and often require surgery.^11,12 The present study noted the greatest mean days away from play in players who sustained finger proximal phalanx (61.5), metacarpal (59.6), finger middle phalanx (44.9), thumb phalanges (43.7), and finger distal phalanx (33.7) fractures. The prolonged time away from participation due to hand fractures can be explained by the high frequency of operative intervention necessary for finger proximal phalanx (34.8%), thumb phalanx (22.5%), metacarpal (16.5%), and finger middle phalanx (14.8%) fractures. Camp et al ⁸ reported that 25.3% (413 of 1633) of injuries sustained while sliding, more commonly head-first, were to the hand, fingers, and thumb, which was supported in our study, where 11% of injuries were due to sliding. In addition to the fact that, in our series, contusions were the most common injuries to the hand (42.4%), the use of protective gloves while batting and running may decrease the total number of days missed from participation.

Similarly, fractures to the wrist can result in marked time away from participation and frequently require operative intervention in MLB and MiLB players. The current study noted that scaphoid fractures and hook of hamate fractures resulted in 73.5 and 51.5 mean days missed per injury, with 60% and 72.4% of these injuries requiring surgical management, respectively. Although the location, type, and chronicity of scaphoid fracture are unknown in our study, surgical treatment for nondisplaced and minimally displaced fractures likely shortened the time to union and permitted earlier return to play.^13-15 Similarly, the type of surgical procedure performed for hook of hamate fractures is unknown, yet hook of hamate excision was likely advised to decrease the time away from play.^16-18 Camp et al ⁸ reported that 9.6% (n = 156) of injuries sustained while sliding occurred in the wrist, mainly with feet-first (n = 113; 12.3%) over head-first (n = 43; 6.0%) slides. With this information, utilization of wrist braces may prevent sprains or fractures that may be sustained during feet-first slides.

The mechanics of batting may be a causative factor in noncontact-related injuries to the wrist. The wrist moves in rapid ulnar deviation with progressive, simultaneous supination and pronation in the lead and dominants hands, respectively, during the hitting and follow-through phases of batting with tremendous angular velocity through the elbow. ¹⁹ Loading of the ulnar side of the wrist with forearm rotation can result in acute or chronic injuries to the TFCC, ulnotriquetral ligament, or extensor carpi ulnaris (ECU) including its subsheath.^20-22 Although these injuries may be unavoidable even with preventive measures, a high index of suspicion for these etiologies of ulnar-sided wrist pain should be maintained in MLB and MiLB players because a delay in diagnosis may prolong recovery or the time to surgery. The current study noted that TFCC tears and ECU subluxation resulted in 47.9 and 41.3 mean days missed from play and required surgery in 32.1% and 46.2% of patients, respectively.

The limitations of this study included the use of a database that relies on accurate diagnosis and classification of the injuries, which is dependent on a variety of personnel involved in the player’s medical care. The foundation of MLB’s EMR system is each club’s AT, who initially reports all complaints and injuries that are subsequently captured by HITS. Although MLB and MiLB ATs are well trained, certain diagnoses could have been incorrectly inputted into the database or were unable to be classified to the various body regions. In addition, mechanisms may not have been accounted for in the HITS database. For example, a TFCC tear could have been entered as a “wrist sprain,” which may explain why the latter was the most common wrist injury. Nonetheless, this study provides comprehensive, epidemiologic information on hand and wrist injuries for all players, level of play, teams, and injuries that resulted in time out of play for professional baseball players.

Injuries to the hand and wrist are common in MLB and MiLB players. Most injuries to this region of the upper extremity are attributed to a contact-related mechanism of injury. Fractures to the hand and wrist can result in tremendous time away from play and often require surgery that can further prolong a player’s duration on the DL and out of play. A thorough understanding of the epidemiology of hand and wrist injuries sustained by professional baseball players may aid hand surgeons in evaluating, treating, and counseling baseball players of all levels on the expected time away from play with operative and nonoperative treatment. Ultimately, we hope that these findings will result in preventive measures that will decrease the prevalence of these injuries.