Stress Fracture of the Trapezoid in a Professional Tennis Player

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. Furthermore, trapezoid fractures are even rarer because of the position and shape of the trapezoid in the wrist joint as described previously.^1-3 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 On the other hand, the mechanism of injury for nontraumatic trapezoid stress fractures is repetitive impact loading, principally on the dorsal aspect of the trapezoid bone in the dominant wrist and thus seen primarily in racket sport athletes.^4-6 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.¹¹ In addition, because of the overlap of the carpal bones in the wrist joint, a trapezoid fracture can be easily missed with plain radiographs.^2,3,5,12

Based 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.¹² Afifi 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.³ One patient presented with swelling, limited ROM of the wrist, and tenderness at the radial aspect of the wrist, while the other patient complained of dull pain at the snuffbox with scaphoid tenderness but no swelling or restricted ROM.³

For nontraumatic sports-related stress fractures, clinical features also varied among the 3 patients reported in the literature and differed from the traumatic cases as well.^4-6 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.⁶ The 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.⁵ The 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.⁴ Our 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.^5,6

The 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.¹³ Simultaneously, 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.^4,14 Stirling and Oliver discussed 19 cases of metacarpal stress fractures in sports, and the second metacarpal was the most commonly injured bone (13 cases, 68%).¹⁵

Because 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.

In our literature review, we found 26 sports-related stress fractures, with 3 cases involving the trapezoid and 23 cases involving only the second metacarpal.^{4-6,13,14,16-22} The data are summarized in Table 1. The time from the onset of symptoms to the clinical presentation ranged from as early as 7 days to 2 years, with the majority of patients seeking consultation within 1 month.^{4,6,13,14,16-19,21,22} All patients received initial radiographs, and they were positive in 9 cases (35%).^16-18,20-22 This percentage of positive radiographs is higher than the 15% described by Anderson¹¹; the difference could be explained by the varying time of presentation for each case. Nevertheless, the incidence did not exceed 50%. Initial radiographs for the trapezoid fractures were negative in all 3 patients.^4-6 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.³ Blomquist 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.⁴

Except for 1 patient who underwent surgery,⁶ all other patients were treated conservatively by either immobilization with splinting/casting or avoiding sports for 4 to 8 weeks.^{4,5,13,14,16-22} Some patients also underwent physical therapy and changed their grip technique, especially in racket sports.^{13,14,16-18,21,22} Symptoms in only 1 patient worsened after her initial visit because she was treated with NSAIDs for 5 weeks without limiting her activity.¹⁹ The 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.^3,6,13,20,23

The 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). Table 2 summarizes the clinical presentations and sports characteristics of the racket sport athletes who were diagnosed with either a trapezoid or second metacarpal fracture.^{4,13,14,16-20,22} 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,^{4,13,14,16-19,22} and all patients except 2 had nonpainful full active ROM of the wrist and fingers. Of these 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^14,16,18,19or had recently increased their training intensity,^{13,14,17,18,20} and they used the western/semi-western grip technique^14,17-20 rather than the eastern grip technique.^13,20 Balius 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 Nevertheless, other cases showed that the western grip played a more significant role than increased training intensity in such fractures.^14,17-19

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.^13,16,17,20 Repeated strokes with a poor grip technique cause repetitive microtrauma that can lead to second metacarpal and trapezoid bone fractures.^{4,6,13,14,16,19,23} As 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.^17,20

The 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.