Stress fracture of the hamulus (hook of hamate) is extremely rare with only a few cases having been reported in literature ^[1,2,3,4]. We present a rare case of stress fracture of the hamulus in a right-handed, club cricket batsman. To the best of our knowledge, this is the first case report of a stress fracture of hamulus in cricketer players till date.

A 23-year-old club team cricketer, who was a right-handed batsman, presented to us with pain in the ulnar side of the left wrist and in the hypothenar area (nondominant hand) since 7 weeks; this was insidious in onset and gradually progressive in intensity. He had no definite history of any acute trauma to this region. Pain typically worsened during batting, and he had difficulty in gripping the bat, and could not execute powerful strokes. On clinical examination, he had deep point tenderness over the hook of the hamate region (Fig. 1). There was no swelling in the region; but grip strength was reduced compared to the opposite side. No symptoms of ulnar nerve compression were elicited. Plain radiographs revealed a sclerotic area in the hamate but were largely inconclusive (Fig. 2).

We asked the patient to bring the cricket bats he used to the clinic and his batting stance and handle grip was examined. We noted that the player used a cricket bat with an extra long handle, and the butt of the handle impinged against the ulnar side of the left wrist and the hypothenar area during batting, reproducing his symptoms (Fig. 3).

Magnetic resonance imaging demonstrated a stress fracture of the hook of the hamate; however, the fracture was not complete, and there was no evidence of any avascular necrosis of the hamate (Fig. 4). He was immobilized in a wrist brace for 4 weeks and put on a rehabilitation protocol; his bat handle and bat grip were modified to minimize pressure over the hamate region. He went back to playing the game within 12 weeks after the initiation of treatment and at 2 years follow-up, he is playing cricket at a club level without any symptoms.

Hamulus (hook of hamate) fractures comprise 2-4% of carpal fractures ^[5,6,7]. These fractures are usually seen in sportspersons. First described by Milch ^[8] in 1934, many subsequent articles in literature detail the incidence, diagnosis, management, and complications of this fracture in different sports (Table 1) ^{[9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25]}. Hamulus fractures are usually seen in sports such as baseball, golf, and tennis where a bat or racquet is used by the athlete ^[7]. The nondominant hand is reportedly injured by swinging a baseball bat or golf club, whereas the dominant hand tends to be more at risk in tennis and other racquet sports ^[26].

In the sport of cricket, only 1 article has reported hamulus fractures so far ^[11]. Belliappa and Barton ^[11] reported 2 hamulus fractures in a case series of 64 hand injuries in 55 cricketers; however, these hamulus fractures were secondary to acute trauma (i.e., the impact of the upper end of the bat handle on the hand) and were not stress injuries. The mechanism of injury leading to an acute hamulus fracture continues to be controversial. Most hamulus fractures are secondary to impact injuries either due to direct trauma (caused by abutment of the hook of hamate on an object or a fall on outstretched hands) or due to an indirect trauma (due to a shearing force applied by the flexor tendon of the small and ring fingers) ^{[9,10,13,16,17,18]}. Stress fractures, on the other hand, are caused by repetitive microtrauma, most often due to the caused by racquet/bat/club and not due to a single traumatic impact injury ^[1]. Guha and Marynissen ^[1] and Van Demark et al. ^[4] reported stress fractures in 2 tennis players secondary to repetitive stress injury caused by the leading edge of the tennis racquet in the dominant hand which were treated conservatively; both athletes responded well to nonoperative treatment and eventually returned to tennis. Scheufler et al. ^[2] reported 3 stress fractures in 2 golfers and 1 tennis player (both in the leading hand) in a series of 14 hamulus fractures. Bayer and Schweizer ^[3] reported a case in a rock climber who repeatedly attempted dynamic swing moves in high-intensity rock bouldering (Table 2). In the case presented above, there was no definite history of any traumatic event, and the pain was insidious in onset, gradually progressed in intensity and typically was aggravated during batting sessions. Furthermore, the fact that the pain responded to rest and alterations in bat grip are retrospectively supportive of a stress injury secondary to repetitive microtrauma due to the free edge of the long bat handle impinging on the hypothenar area while executing batting strokes. Stress fractures if picked up early and treated by immobilization usually heal well allowing early return to sport ^[1]. If the diagnosis is delayed, the results of nonoperative treatment deteriorate, and the patient is more likely to need surgical treatment (either excision or open reduction and internal fixation [ORIF]) ^[2].

Management of hamulus fractures
Hamulus fractures can be treated nonoperatively with cast immobilization or operatively by ORIF (with Kirschner wires or screws) or fragment excision ^[6].

A high, unidentified number of hamulus fractures remain asymptomatic and either do not require or seek treatment. However, nonoperative management may lead to secondary complications such as painful nonunion, flexor digitorum profundus or superficialis tenosynovitis, and tendon rupture and is also associated with a long period of immobilization. Milek et al. reported a 15% incidence of tendon ruptures (18/257 cases) in hamulus fracture cases treated nonoperatively ^[27].

Excision of the hamulus is currently the preferred surgery of choice for most hand surgeons as evidenced by our literature review (Table 1); however, it leads to a reported 11% decrease in the flexor tendon excursion due to geometric factors ^[28]. There are also chances of residual pain,impaired sensation, and weakening of grip strength ^[2]. Scheufer et al. reported no significant difference in the grip strength between patients who received ORIF and those who received hamulus excision, although the grip strength values are slightly higher in the ORIF group. They hypothesized that in the young, active population who work under strenuous conditions, ORIF with screws should be preferred over hamulus excision and also over ORIF with K-wires; the reasons being better grasp, anatomic restoration of the pulley mechanism for the 4th and 5th longflexor tendons and shorter immobilization time (around 2 weeks) in ORIF with screws group ^[2].

Ulnar-sided pain and tenderness in players of racquet sports or those using clubs/bats have to be carefully evaluated. The dominant hand in tennis or sports involving single hand grip, and the nondominant hand in double grip sports may be the site of ulnar-sided stress concentration, leading to a stress fracture. MRI should be used to evaluate the wrist in all such cases. Nonoperative treatment, change of grip and adequate rehabilitation give good outcomes in almost all cases.

Hamulus stress fractures can occur in the non-leading hand of a cricket batsman as in other sports with a double-hand grip. The stress fracture is usually secondary to a long bat handle which leads to repeated impingement on the hook of the hamulus. Plain radiographs are usually inconclusive; MRI or bone scan is necessary to clinch the diagnosis. Non-operative treatment along with a change in the bat grip usually leads to fracture union and a good functional outcome with return to active sport. Excision of the hamate or ORIF may be needed in chronic/recalcitrant cases.