Stress Fracture of the Trapezoid in a Professional Tennis Player

Background: Repetitive microtrauma can lead to trapezoid and second metacarpal stress fractures in racket sport players. Nontraumatic trapezoid stress fractures are rare and difficult to diagnose. To our knowledge, only 3 cases had been reported as of May 2023. We report the fourth case of a nontraumatic sports-related trapezoid stress fracture and only the second case in a tennis player. Case Report: A 29-year-old professional and right hand–dominant male tennis player presented with right hand and wrist pain for 3 weeks. He complained of dorsal wrist tenderness proximal to the base of the second metacarpal that was exacerbated by extension of the index finger. Initial radiographs were normal, but magnetic resonance imaging of the wrist showed a stress fracture of the trapezoid bone and base of the second metacarpal. The patient was treated conservatively with a wrist brace, cessation of sports activities, and modification of his training routine. The patient was asymptomatic at 1-year follow-up. Conclusion: This case highlights the relationship between trapezoid and second metacarpal stress fractures in athletes. A high index of suspicion for trapezoid stress fractures should be maintained and included in every differential diagnosis for athletes, especially racket sport players presenting with wrist pain. To avoid future injuries, clinicians should not only treat the fracture but also address the risk factors predisposing to this injury.


INTRODUCTION
Trapezoid fracture is the least common carpal bone fracture, accounting for only 0.4% of total carpal bone fractures. 1The rarity of this fracture is because of the shape and position of the trapezoid within the wrist joint.2][3] The trapezoid has a wedge shape and is 2 times wider dorsally than it is volarly, making it a keystone for the carpal arch. 1 The mechanism of injury described in the literature usually involves a high-energy trauma or fall.In these situations, a considerable amount of axial force or bending stress is transmitted indirectly from the second metacarpal base to the trapezoid with or without wrist flexion or extension. 3,4Such traumatic injuries are usually accompanied by concomitant fractures of other carpal bones and metacarpals. 4,5On the other hand, nontraumatic trapezoid fractures are extremely rare, with, to our knowledge, only 3 cases reported as of May 2023.5][6] We report the fourth case of nontraumatic sports-related trapezoid stress fracture and the second case in a tennis player.
Because our patient also had a stress fracture of the base of the second metacarpal, we conducted a literature review of nontraumatic trapezoid and second metacarpal stress fractures with a focus on the characteristics of such fractures in racket sport athletes.

CASE REPORT
A 29-year-old professional right hand-dominant male tennis player presented to our facility complaining of right dorsal hand and wrist pain for the prior 3 weeks.The pain was localized at the region of the base of the second metacarpal and had progressively increased when the patient doubled the amount and intensity of his tennis training to 3 hours daily in preparation for a major tournament.The patient denied any history of trauma.He swung his racket using the western grip technique (Figures 1 and 2) and experienced pain principally during serving and forehand strokes.On physical examination, the patient had point tenderness over the dorsal aspect of the wrist proximal to the level of the base of the second metacarpal.He complained of pain only during extension of the index finger.Otherwise, he had full nonpainful active range of motion (ROM) of the wrist and fingers and had no swelling, masses, or deformities.Radiographs of the right wrist were normal (Figure 3).Tendonitis of the extensor tendons was suspected, and the patient was treated conservatively with nonsteroidal anti-inflammatory drugs (NSAIDs) without avoidance of sports.However, the pain persisted and worsened after 1 week.
Magnetic resonance imaging (MRI) showed bone marrow edema of the trapezoid and radial aspect of the base of the second metacarpal (Figure 4).The patient was diagnosed with a stress fracture of both the trapezoid bone and base of the second metacarpal and was treated with a wrist brace for 4 weeks along with avoidance of all sports.The patient was also advised to revert to his initial training routines without doubling the amount and intensity and to change his grip technique if possible.Our patient did not change his  grip technique, but he altered his stroke biomechanics and decreased his training intensity.He was symptom-free at 6-week and 1-year follow-ups.

DISCUSSION
Although metacarpal stress fractures are uncommon and account for only 1.4% of all fractures, 7,8 a carpal stress fracture percentage has not been reported.2][3] Identification of a trapezoid fracture is usually easier when concomitant fractures coexist in the same joint.Such injuries occur as a result of direct high-energy trauma, and imaging such as MRI or computed tomography (CT) scans are usually ordered at presentation for diagnosis. 9,10][6] A study by Anderson revealed that only 15% of initial radiographs are positive for upper extremity stress fractures, and the incidence increases to only 50% over time. 11In addition, because of the overlap of the carpal bones in the wrist joint, a trapezoid fracture can be easily missed with plain radiographs. 2,3,5,12ased on the case reports in the literature, clinical presentation seems to slightly differ among patients with traumatic trapezoid fractures.Sadowski and Montilla reported a patient with traumatic trapezoid fracture who presented with swelling, decreased ROM of the wrist, pain at the base of the second metacarpal, and snuffbox tenderness. 12Afifi and Lu reported similar symptoms after trauma but with the absence of snuffbox tenderness. 2 Nammour et al described 2 patients with traumatic trapezoid fractures. 35][6] A baseball player presented with swelling and tenderness over the trapezoid region, pain only with axial compression of the index finger, and normal ROM in the wrist. 6The shot putter presented with pain and tenderness at the proximal aspect of the first and second metacarpal that was exacerbated by thumb and index finger extension and abduction. 5The tennis player presented with wrist pain and point tenderness over the trapezoid, minimal tenderness over the scapholunate interval, and no wrist swelling or ROM restriction. 4ur patient presented with pain and tenderness over the region of the trapezoid that was exacerbated with index finger extension but no swelling or ROM restriction.
With such an unpredictable clinical presentation and the low incidence of fracture detection on plain radiographs at initial presentation, clinicians should have a high index of suspicion for these fractures.Depending on the clinical presentation, further investigation should be carried out either by CT scan, MRI, or bone scintigraphy. 5,6he second metacarpal bone is long, has the widest base compared to other metacarpals, and articulates with the trapezoid, trapezium, capitate, and third metacarpal.The base of the second metacarpal bone receives maximum tension when the hand grips a tool. 13Simultaneously, slight metacarpal bone flexion can cause an axial load force on the dorsal aspect of the trapezoid, and this force can ultimately cause the trapezoid to fracture or dorsally dislocate. 4,14Stirling and Oliver discussed 19 cases of metacarpal stress fractures in sports, and the second metacarpal was the most commonly injured bone (13 cases, 68%). 15ecause of the rarity of nontraumatic sports-related trapezoid fractures and the close relationship between the trapezoid and second metacarpal, we conducted a literature review targeting both bones and focusing on racket sport athletes with the goal of providing a guide for physicians to diagnose such fractures without delays.We summarize the clinical presentation of each patient and address the risk factors and clinical outcomes after management.
16][17][18][19][20][21][22] The data are summarized in Table 1.[20][21][22] This percentage of positive radiographs is higher than the 15% described by Anderson 11 ; the difference could be explained by the varying time of presentation for each case.Nevertheless, the incidence did not exceed 50%.5][6] Other imaging modalities reported were MRI (the most common at 20 cases), followed by bone scintigraphy (5 cases) and CT scan (3 cases).No consensus has been reached on what type of imaging should be used after an initial radiograph.While bone scintigraphy has been used, 5,6,17,20 MRI and CT scans are faster, are more readily available, and provide detailed information that can guide treatment. 3Blomquist et al showed that MRI has a higher sensitivity and specificity compared to CT scan in identifying trapezoid fractures and provides additional information regarding secondary injuries whether they are soft tissue or bone related. 421,22 Symptoms in only 1 patient worsened after her initial visit because she was treated with NSAIDs for 5 weeks without limiting her activity. 19he patient ultimately improved after cessation of sports.This result is somewhat similar to our case in which the patient's symptoms worsened after 1 week of treatment of NSAIDs without avoiding sports activities, thus highlighting the importance of sports cessation during the first few weeks of treatment to relieve the repetitive stress on the fractured bone.Our patient was then managed conservatively with a short arm wrist brace and avoidance of sport activities for 4 weeks.Our patient did not change his grip technique, but he decreased the intensity of his training and adjusted his stroke biomechanics.This management was consistent with several studies that support conservative management by limiting sport activities or immobilizing the extremity for nondisplaced fractures and limiting surgical intervention to those with displaced fractures or concomitant fractures. 3,6,13,20,23he most common type of sport associated with trapezoid and second metacarpal fractures was racket sports (21/26, 81%), including tennis, badminton, and soft tennis (16 vs 3 vs 2 cases respectively, Table 1).18][19][20]22 In this subgroup, only 1 case of trapezoid stress fracture was reported; 4 the remaining cases involved the second metacarpal, with the base and shaft almost equally affected (9 vs 8 cases respectively, Table 2).The dominant hand was injured in all patients, and they all complained of either wrist or hand pain with racket gripping, serving, or forehand stroking, similarly to our patient.On physical examination, point tenderness over the region of the second metacarpal and trapezoid was evident in multiple cases, 4,13,14,[16][17][18][19]22 and all patients except 2 had nonpainful full active ROM of the wrist and fingers. Of hese 2 patients, 1 reported pain with index finger extension and the other reported mild pain at the extremes of the ROM.4,19 Swelling or induration was reported in 38% of cases (8 cases) 14,18,20 and a hard mass in 1 case.14 These cases demonstrate the diversity in clinical presentation as described earlier.
Other factors that played an important role in these stress fractures were the duration and intensity of training and the athlete's grip technique.The cases reported in Table 2 show that most players either trained several hours daily 14,16,18,19 or had recently increased their training intensity, 13,14,17,18,20 and they used the western/semi-western grip technique 14,[17][18][19][20] rather than the eastern grip technique. 13,20Balius et al mainly focused on the change in training intensity, especially in forehand strokes, which they believed to be a more important factor in stress fractures than grip technique. 20][19] In tennis, the player's hand and wrist are subjected to immensely high pressure and force that are transmitted from the racket during every stroke. 13,16,17,20Repeated strokes with a poor grip technique cause repetitive microtrauma that can lead to second metacarpal and trapezoid bone fractures. 4,6,13,14,16,19,23As indicated by the cases reported in Table 2, the western grip technique seems to be associated with more injuries than the eastern grip technique.The main difference between the techniques is the position of the palm with respect to the racket handle (Figures 1 and 2).In the eastern grip, the palm is perpendicular to the racket surface, but the palm is parallel in the western grip, altering the biomechanics and increasing the weight on the second metacarpal, thus transferring all the tension to its base. 17,20he correlation between training intensity and technique explains why managing such injuries not only depends on rest and avoidance of sports but also on changing the grip technique or improving the biomechanics of the strokes to decrease the tension on the base of the second metacarpal.

CONCLUSION
This case highlights the relation between trapezoid and second metacarpal stress fractures in athletes and shows the importance of history and physical examination in diagnosing such rare fractures, especially because of their varying clinical presentations.Trapezoid stress fractures should be considered in every differential diagnosis for athletes, especially for racket sport players presenting with wrist pain.Clinicians should identify the mechanism of the injury as soon as possible and be able to address not only the fracture itself but also the extent of play time, the modification of training dynamics and intensity, and the grip technique for all racket sport athletes to help prevent future injuries.

Figure 1 .
Figure 1.Eastern and western grip techniques.

Figure 2 .
Figure 2. Racket handle bevel numbering for a right hander.Bevel 3: location of the palm side of the index finger knuckle in an eastern grip technique; Bevel 5: location of the palm side of the index finger knuckle in a western grip technique.

Figure 3 .
Figure 3. Unremarkable (A) posteroanterior and (B) lateral radiographs of the right wrist show no evidence of acute fracture.

Figure 4 .
Figure 4. Magnetic resonance imaging of the right wrist-(A and C) sagittal fat suppressed proton density (PD FS), (E and F) coronal PD FS, and (B and D) sagittal T1 images-showing bone marrow edema on opposing sides of the second carpometacarpal joint, predominantly involving the radial aspect of both trapezoid and base of the second metacarpal bones (yellow arrows).Imaging shows no evidence of periosteal reaction or low T1 fracture line (red arrows show only ill-defined edema), and findings are in keeping with a microtrabecular injury.

Table 1 . Reports of Nontraumatic Stress Fractures of the Trapezoid and Second Metacarpal Bones
Fracture

Table 2 . Reports of Nontraumatic Racket Sports-Related Stress Fractures of the Trapezoid and Second Metacarpal Bones Play Time
F, female; M, male; NA, not available; ROM, range of motion.