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Avulsion Fracture of the Extensor Carpi Radialis Brevis Insertion
AVULSION FRACTURE OF THE EXTENSOR CARPI RADIALIS BREVIS INSERTION E. TSIRIDIS, J. KOHLS-GATZOULIS and C. SCHIZAS From the Department of Orthopaedics, The Whittington Hospital, London, UK
Avulsion of the extensor carpi radialis brevis at wrist level is rare. We present a case of an avulsion fracture involving the extensor carpi radialis brevis insertion at the base of the middle finger metacarpal. Journal of Hand Surgery (British and European Volume, 2001) 26B: 6: 596–598 INTRODUCTION Avulsion fractures involving the insertions of the radial extensors at the bases of the index and middle metacarpals are rare injuries. Avulsion fractures at the site of insertion of extensor carpi radialis longus on the index metacarpal have been reported in eight patients (Boles and Durbin, 1999). Avulsion fractures involving the extensor carpi radialis brevis insertion on the base of the middle finger metacarpal have been reported in five cases, three in the English literature (Boles and Durbin, 1999; Cobbs et al., 1996; Rotman and Pruitt, 1993) and two in the German literature (Voigt, 1989; Hocker and Spitz, 2000). We report an avulsion fracture of the extensor carpi radialis brevis insertion, which was treated with open reduction and internal fixation of the avulsed bony fragment with simultaneous reattachment of the tendon using a suture anchor.
Fig 1 Lateral radiograph of hand and wrist showing a fracture of the base of the third metacarpal bone.
CASE REPORT A 32-year-old man injured his dominant right hand by striking the side of a vehicle while cycling. The patient recalled hitting his clenched fist on the vehicle with his elbow in full extension, his forearm in pronation and his wrist in flexion. He experienced immediate pain on the dorsum of his wrist where there was a visible hard lump. On clinical examination, there was no break in the skin and neurovascular examination was normal. Although the patient had some active extension of the wrist, this was painful, with the pain radiating to the common extensor origin. Palpation proximal to the bony prominence reproduced the symptoms on the dorsum of the forearm. The plain anteroposterior and lateral radiographs showed a displaced dorsal fragment, the origin of which was difficult to visualize (Fig. 1). A computed tomography scan showed that the fragment originated from the base of the middle finger metacarpal and was a major component of the carpometacarpal articulation (Fig. 2). The fracture was exposed through a dorsal longitudinal incision over the second web space. The extensor carpi radialis brevis tendon had been partially avulsed from the fragment which involved 50% of the articular surface. The fragment was reduced and fixed
Fig 2 Axial CT of wrist demonstrating the avulsion fracture of base of third metacarpal bone.
with a 2.0-mm lag screw and the extensor carpi radialis brevis tendon was reattached to the base of the third metacarpal with a 0 polyester suture anchor (Mitek, Johnson and Johnson) (Fig. 3). After surgery, the wrist was immobilized in a belowelbow cast with the wrist in slight extension for 6 weeks. 596
ECRB AVULSION
Fig 3 AP radiograph of hand and wrist taken 2 months postoperatively. The lag screw and suture anchor are seen.
Six months after surgery, the patient had regained almost-full grip strength and extension power.
DISCUSSION The rarity of Extensor carpi radialis brevis avulsion fractures lies partly in its mechanism of injury. In our patient this was a flexion moment at the wrist, combined with simultaneous contraction of the extensor carpi radialis brevis with the elbow in full extension and the fist clenched. This is similar to the mechanism proposed by other authors (Crichlow and Hoskinson, 1988; DeLee, 1979; Treble and Arif, 1987). The bony anatomy of the base of the third metacarpal bone may offer an explanation as to why extensor carpi radialis brevis avulsion fractures occur. Its short styloid process projecting proximally distinguishes the base of the third metacarpal, which articulates with the capitate by means of a facet which is concave in its dorsal portion, where it covers the styloid process. The radial aspect of the base articulates with the index metacarpal and the ulnar aspect articulates with the ring finger metacarpal. The palmar surface of the base receives a slip from the flexor carpi radialis tendon, while the extensor carpi radialis brevis tendon inserts onto the dorsal surface, immediately beyond the styloid process. The bases of the second, third, fourth and fifth metacarpal bones articulate with one another by small facets and are connected together by dorsal, palmar and interosseous ligaments. The bony architecture, with its ligamentous reinforcements, allows
597
virtually no movement at the middle finger carpometacarpal joint (Williams and Warwick, 1980). Furthermore, it has been suggested that the rigidity with which the base of the third metacarpal is held in place explains why an avulsion fracture occurs, rather than a carpometacarpal dislocation (Treble and Arif, 1987). The extensor carpi radialis brevis has greater involvement in wrist extension than extensor carpi radialis longus, and it stabilizes the wrist in extension during gripping. The extensor carpi radialis longus, on the other hand, is mainly involved in radial deviation of the wrist (Brand et al., 1981). The extensor carpi radialis brevis tendon’s role as a wrist stabilizer and extensor is the major argument for reattachment of the avulsed fragment (Rotman and Pruitt, 1993). Secondly, the reduction of the bony fragment restores the integrity of the joint surface (DeLee, 1979) and finally, reduction of the fragment prevents it from abrading the finger extensor tendons, which could lead to late rupture (Treble and Arif, 1987). In the three early case reports, the extensor carpi radialis brevis avulsion fractures were treated with tension-band wiring (Cobbs et al., 1996; Rotman and Pruitt, 1993; Voigt, 1989), whereas in the two recent reports screw fixation was employed (Boles and Durbin, 1999; Ho¨cker and Spitz, 2000). In the majority of these cases the extensor carpi radialis brevis tendon was avulsed with the bone and so internal fixation of the avulsion fragment sufficed. Our case is unusual in that there was avulsion of the extensor carpi radialis brevis tendon from the bony fragment as well, which has been described only once before (Boles and Durbin, 1999). Simple avulsion fractures, in which the tendon is still attached to the fragment, can be reduced by tension-band wiring or by screw fixation. However, when the tendon is also avulsed from the fragment, both injuries must be addressed. In our case this was accomplished by using a 2-mm screw to fix the bony fragment and a suture anchor to reattach the extensor carpi radialis brevis tendon. Due to its mechanism of injury and its bony anatomy, avulsion fractures of the extensor carpi radialis brevis are rare injuries. Open reduction and internal fixation restore the function of an important wrist extensor, reduce an intra-articular fracture and prevent late rupture of the long extensors.
References Boles SD, Durbin RA (1999). Simultaneous ipsilateral avulsion of the extensor carpi radialis longus and brevis tendon insertions: case report and review of the literature. Journal of Hand Surgery, 24A: 845–849. Brand PW, Beach RB, Thompson DE (1981). Relative tension and potential excursion of muscles in the forearm and hand. Journal of Hand Surgery, 6A: 209–219. Crichlow TPKR, Hoskinson J (1988). Avulsion fracture of the index metacarpal base: three case reports. Journal of Hand Surgery, 13B: 212–214.
598 Cobbs KF, Owens WS, Berg EE (1996). Extensor carpi radialis brevis avulsion fracture of the long finger metacarpal: a case report. Journal of Hand Surgery, 21A: 684–686. DeLee JC (1979). Avulsion fracture of the base of the second metacarpal by the extensor carpi radialis longus. a case report. Journal of Bone and Joint Surgery, 61A: 445–446. Ho¨cker K, Spitz H (2000). Osseous avulsion injury of the extensor carpi radialis brevis tendon from the base of the 3rd metacarpal bone. Handchirurgie Mikrochirurgie Plastische Chirurgie, 32: 112–114. Rotman MB, Pruitt DL (1993). Avulsion fracture of the extensor carpi radialis brevis insertion. Journal of Hand Surgery, 18A: 511–513. Treble N, Arif S (1987). Avulsion fracture of the index metacarpal. Journal of Hand Surgery, 12B: 38–39.
THE JOURNAL OF HAND SURGERY VOL. 24B No. 6 DECEMBER 1999 Voigt C (1989). Osseous rupture of the attachment of the tendon of the extensor carpi radialis brevis muscle. Handchirurgie Mikrochirurgie Plastische Chirurgie, 21: 331–333. Williams PL, Warwick R. Grays Anatomy, 36th edn. Edinburgh: ChurchillLivingston, 1980: 471. Received: 23 April 2001 Accepted after revision: 26 June 2001 Mr. C. Schizas, The Whittington Hospital, Department of Orthopaedics, Highgate Hill, London N19 5NF UK. Email:[email protected] # 2001 The British Society for Surgery of the Hand doi: 10.1054/jhsb.2001.0662, available online at http://www.idealibrary.com on
Avulsion of the extensor carpi radialis brevis at wrist level is rare. We present a case of an avulsion fracture involving the extensor carpi radialis brevis insertion at the base of the middle finger metacarpal. Journal of Hand Surgery (British and European Volume, 2001) 26B: 6: 596–598 INTRODUCTION Avulsion fractures involving the insertions of the radial extensors at the bases of the index and middle metacarpals are rare injuries. Avulsion fractures at the site of insertion of extensor carpi radialis longus on the index metacarpal have been reported in eight patients (Boles and Durbin, 1999). Avulsion fractures involving the extensor carpi radialis brevis insertion on the base of the middle finger metacarpal have been reported in five cases, three in the English literature (Boles and Durbin, 1999; Cobbs et al., 1996; Rotman and Pruitt, 1993) and two in the German literature (Voigt, 1989; Hocker and Spitz, 2000). We report an avulsion fracture of the extensor carpi radialis brevis insertion, which was treated with open reduction and internal fixation of the avulsed bony fragment with simultaneous reattachment of the tendon using a suture anchor.
Fig 1 Lateral radiograph of hand and wrist showing a fracture of the base of the third metacarpal bone.
CASE REPORT A 32-year-old man injured his dominant right hand by striking the side of a vehicle while cycling. The patient recalled hitting his clenched fist on the vehicle with his elbow in full extension, his forearm in pronation and his wrist in flexion. He experienced immediate pain on the dorsum of his wrist where there was a visible hard lump. On clinical examination, there was no break in the skin and neurovascular examination was normal. Although the patient had some active extension of the wrist, this was painful, with the pain radiating to the common extensor origin. Palpation proximal to the bony prominence reproduced the symptoms on the dorsum of the forearm. The plain anteroposterior and lateral radiographs showed a displaced dorsal fragment, the origin of which was difficult to visualize (Fig. 1). A computed tomography scan showed that the fragment originated from the base of the middle finger metacarpal and was a major component of the carpometacarpal articulation (Fig. 2). The fracture was exposed through a dorsal longitudinal incision over the second web space. The extensor carpi radialis brevis tendon had been partially avulsed from the fragment which involved 50% of the articular surface. The fragment was reduced and fixed
Fig 2 Axial CT of wrist demonstrating the avulsion fracture of base of third metacarpal bone.
with a 2.0-mm lag screw and the extensor carpi radialis brevis tendon was reattached to the base of the third metacarpal with a 0 polyester suture anchor (Mitek, Johnson and Johnson) (Fig. 3). After surgery, the wrist was immobilized in a belowelbow cast with the wrist in slight extension for 6 weeks. 596
ECRB AVULSION
Fig 3 AP radiograph of hand and wrist taken 2 months postoperatively. The lag screw and suture anchor are seen.
Six months after surgery, the patient had regained almost-full grip strength and extension power.
DISCUSSION The rarity of Extensor carpi radialis brevis avulsion fractures lies partly in its mechanism of injury. In our patient this was a flexion moment at the wrist, combined with simultaneous contraction of the extensor carpi radialis brevis with the elbow in full extension and the fist clenched. This is similar to the mechanism proposed by other authors (Crichlow and Hoskinson, 1988; DeLee, 1979; Treble and Arif, 1987). The bony anatomy of the base of the third metacarpal bone may offer an explanation as to why extensor carpi radialis brevis avulsion fractures occur. Its short styloid process projecting proximally distinguishes the base of the third metacarpal, which articulates with the capitate by means of a facet which is concave in its dorsal portion, where it covers the styloid process. The radial aspect of the base articulates with the index metacarpal and the ulnar aspect articulates with the ring finger metacarpal. The palmar surface of the base receives a slip from the flexor carpi radialis tendon, while the extensor carpi radialis brevis tendon inserts onto the dorsal surface, immediately beyond the styloid process. The bases of the second, third, fourth and fifth metacarpal bones articulate with one another by small facets and are connected together by dorsal, palmar and interosseous ligaments. The bony architecture, with its ligamentous reinforcements, allows
597
virtually no movement at the middle finger carpometacarpal joint (Williams and Warwick, 1980). Furthermore, it has been suggested that the rigidity with which the base of the third metacarpal is held in place explains why an avulsion fracture occurs, rather than a carpometacarpal dislocation (Treble and Arif, 1987). The extensor carpi radialis brevis has greater involvement in wrist extension than extensor carpi radialis longus, and it stabilizes the wrist in extension during gripping. The extensor carpi radialis longus, on the other hand, is mainly involved in radial deviation of the wrist (Brand et al., 1981). The extensor carpi radialis brevis tendon’s role as a wrist stabilizer and extensor is the major argument for reattachment of the avulsed fragment (Rotman and Pruitt, 1993). Secondly, the reduction of the bony fragment restores the integrity of the joint surface (DeLee, 1979) and finally, reduction of the fragment prevents it from abrading the finger extensor tendons, which could lead to late rupture (Treble and Arif, 1987). In the three early case reports, the extensor carpi radialis brevis avulsion fractures were treated with tension-band wiring (Cobbs et al., 1996; Rotman and Pruitt, 1993; Voigt, 1989), whereas in the two recent reports screw fixation was employed (Boles and Durbin, 1999; Ho¨cker and Spitz, 2000). In the majority of these cases the extensor carpi radialis brevis tendon was avulsed with the bone and so internal fixation of the avulsion fragment sufficed. Our case is unusual in that there was avulsion of the extensor carpi radialis brevis tendon from the bony fragment as well, which has been described only once before (Boles and Durbin, 1999). Simple avulsion fractures, in which the tendon is still attached to the fragment, can be reduced by tension-band wiring or by screw fixation. However, when the tendon is also avulsed from the fragment, both injuries must be addressed. In our case this was accomplished by using a 2-mm screw to fix the bony fragment and a suture anchor to reattach the extensor carpi radialis brevis tendon. Due to its mechanism of injury and its bony anatomy, avulsion fractures of the extensor carpi radialis brevis are rare injuries. Open reduction and internal fixation restore the function of an important wrist extensor, reduce an intra-articular fracture and prevent late rupture of the long extensors.
References Boles SD, Durbin RA (1999). Simultaneous ipsilateral avulsion of the extensor carpi radialis longus and brevis tendon insertions: case report and review of the literature. Journal of Hand Surgery, 24A: 845–849. Brand PW, Beach RB, Thompson DE (1981). Relative tension and potential excursion of muscles in the forearm and hand. Journal of Hand Surgery, 6A: 209–219. Crichlow TPKR, Hoskinson J (1988). Avulsion fracture of the index metacarpal base: three case reports. Journal of Hand Surgery, 13B: 212–214.
598 Cobbs KF, Owens WS, Berg EE (1996). Extensor carpi radialis brevis avulsion fracture of the long finger metacarpal: a case report. Journal of Hand Surgery, 21A: 684–686. DeLee JC (1979). Avulsion fracture of the base of the second metacarpal by the extensor carpi radialis longus. a case report. Journal of Bone and Joint Surgery, 61A: 445–446. Ho¨cker K, Spitz H (2000). Osseous avulsion injury of the extensor carpi radialis brevis tendon from the base of the 3rd metacarpal bone. Handchirurgie Mikrochirurgie Plastische Chirurgie, 32: 112–114. Rotman MB, Pruitt DL (1993). Avulsion fracture of the extensor carpi radialis brevis insertion. Journal of Hand Surgery, 18A: 511–513. Treble N, Arif S (1987). Avulsion fracture of the index metacarpal. Journal of Hand Surgery, 12B: 38–39.
THE JOURNAL OF HAND SURGERY VOL. 24B No. 6 DECEMBER 1999 Voigt C (1989). Osseous rupture of the attachment of the tendon of the extensor carpi radialis brevis muscle. Handchirurgie Mikrochirurgie Plastische Chirurgie, 21: 331–333. Williams PL, Warwick R. Grays Anatomy, 36th edn. Edinburgh: ChurchillLivingston, 1980: 471. Received: 23 April 2001 Accepted after revision: 26 June 2001 Mr. C. Schizas, The Whittington Hospital, Department of Orthopaedics, Highgate Hill, London N19 5NF UK. Email:[email protected] # 2001 The British Society for Surgery of the Hand doi: 10.1054/jhsb.2001.0662, available online at http://www.idealibrary.com on