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Spontaneous Flexor Tendon Rupture of the Flexor Digitorum Profundus Secondary to an Anatomic Variant
Spontaneous Flexor Tendon Rupture of the Flexor Digitorum Profundus Secondary to an Anatomic Variant Fujioka Masaki, MD, Tasaki Isao, MD, Yakabe Aya, MD, Ichimura Ryuuji, MD, Matsuoka Yohjiroh, MD From the Department of Plastic and Reconstructive Surgery and the Department of Radiology, National Nagasaki Medical Center, Nagasaki, Japan.
We report a case of the flexor digitorum profundus tendon rupture of the little finger, which was predisposed by an anatomic variation of the tendon. Intraoperative findings and magnetic resonance imaging of the opposite hand suggested that the flexor digitorum profundus tendons of the ring and the little finger bifurcated. The patient had tendon reconstruction and regained function. We believe that reconstructing the tendon so that it resembles the normal anatomy prevents the recurrence of tendon rupture. (J Hand Surg 2007;32A:1195–1199. Copyright © 2007 by the American Society for Surgery of the Hand.) Key words: Flexor digitorum profundus, spontaneous flexor tendon rupture, variation of flexor tendons.
ost reported cases of closed flexor digitorum profundus (FDP) tendon rupture are associated with inflammatory arthritis disorders, such as rheumatoid arthritis and gout. Other cases of flexor tendon rupture in otherwise healthy persons are usually associated with bony abnormalities such as old fractures of carpal bones and the distal radius and Kienböck’s disease.1–5 Excluding such cases with clear causes, most flexor tendon ruptures are caused by avulsion of the FDP from its insertion in the ring finger when an athlete grasps an opponent’s clothing strongly.6 We report an unusual case of spontaneous flexor tendon rupture in the little finger predisposed by an anatomic variation in both hands, which was identified by the intraoperative finding and magnetic resonance imaging finding of the opposite hand.
M
Case Report A 26-year-old man noted the inability to flex his nondominant left little finger at the distal interphalangeal joint (Fig. 1). Two days earlier, he had firmly gripped an opponent’s clothing during a rugby game but sustained no open wound. He had no history of previous hand injury or disease, including inflammatory arthritis. A FDP rupture was diagnosed, and tendon suture was planned for 1 week after injury. Surgical exploration revealed that the distal tendon
Figure 1. Preoperative photograph showing loss of flexion of the left little finger distalinterphalangeal joint.
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Figure 2. (A) The flexor digitorum profundus (FDP) tendon had ruptured in the midpalm. The stump was oblique. (B) The proximal FDP tendon stump was not found, although the incision was extended to the forearm. FDPIV, flexor digitorum profundus tendon IV; FCU, flexor carpi ulnaris tendon.
stump of the ruptured FDP tendon was at the level of the midpalm (zone 3). The short distal end of the tendon stump was oblique as if it had been torn off, but it showed inflammatory degeneration (Fig. 2A). There was no bony prominence within the palm or carpal tunnel. The proximal FDP tendon stump was not found, although the incision was extended to the forearm (Fig. 2B). The ruptured tendon was reconstructed using a palmaris longus tendon graft. The distal stump suture to the grafted tendon was performed with the interlacing suture technique, and the proximal suture was performed with end-to-side suture of the graft into the FDP tendon of the ring finger. The proximal connection was placed in the forearm to avoid tendon adhesion in zone 2 and the carpal tunnel (Fig. 3). Active mobilization was started 2 weeks later, and the repair was protected by a splint for 6 weeks. Six months after surgery, the patient had active distal interphalangeal joint motion range of 0 to 65 degrees and regained a strong grip and excellent use of the hand (Fig. 4).
Magnetic resonance imaging (MRI) of the opposite hand was performed 1 week after surgery to investigate variations of the FDP tendons. The MRI scan revealed that the FDP tendon of the little finger was not isolated but branched from the FDP of the ring finger at midpalm (Fig. 5).
Discussion Most cases of flexor tendon rupture are associated with rheumatoid arthritis or traumatic or congenital bony abnormalities.1,3–5 Spontaneous flexor tendon rupture without these inflammatory and bony factors is rare. Several investigators have described cases of true spontaneous FDP and flexor pollicis longus tendon ruptures: McLain and Steyer reported 3 cases, Imbriglia and Goldstein reported 10 cases, Boyes et al reported 3 cases, and Folmar et al reported 2 cases.6 –9 The cause of these ruptures, however, remains unclear. It is curious that tendon ruptures occur in the intratendinous portion, because the insertion junction
Masaki et al / Spontaneous Flexor Tendon Rupture of the Flexor Digitorum Profundus
Figure 3. (A) Schematic representation of the FDP tendons. The FDP tendon of the little finger bifurcated from the tendon of the ring finger at midpalm and ruptured at this point. (B) The tendon was reattached to the FDP of the ring finger by interposing a palmaris longus tendon graft proximal to the carpal tunnel.
is the weakest point of the musculotendinous unit. When forceful extension loads the FDP, avulsion of the tendon should occur at its insertion portion. McLain and Steyer have suggested that these intratendinous ruptures result from tendon weakness due to repeated microtrauma or vascular compromise.7 Davis and Armstrong have reported two cases of spontaneous flexor tendon rupture due to tendon variations, which represents a new explanation for tendon rupture.10 Surgical exploration of their 2 cases revealed that the FDP tendon to the ring finger had sheared cleanly off at the level of the superficial palmar arch. We made an identical operative exploration in our case and found neither a proximal FDP tendon stump nor marks of tendon avulsion on the common FDP muscle. The FDP tendons usually arise from a common muscle, and the 2 ulnar FDP tendons tend to originate from the same muscle belly and separate in the forearm or carpal tunnel.11 The magnetic resonance image of the patient’s right hand showed a variant of the FDP little finger tendon in which the tendons of the little and ring finger appeared to be fused side-to-side at the midpalmar level. The tendons of the left hand might have had the same variation. When the pulling stress loaded the little finger, the tendon bifurcation, which was the weakest point against shearing forces, tore and ruptured. We believe that this anatomic anomaly predisposed to FDP tendon rupture. Suggested methods for surgical reconstruction include direct repair, tendon grafting, and tendon transfer. Results are believed to depend primarily on the
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time since rupture and the location of the injury. Naam reported surgical results of 13 patients with spontaneous FDP tendon rupture: 7 patients had direct repair, 5 had tendon grafting, and 1 had tendon transfer. He concluded that patients who had early direct repair had better functional results than those who were treated with tendon grafting or tendon transfer.12 McLain et al have also concluded that the results of direct repair within 1 week of rupture are superior to the results of late reconstruction.7 If both the distal and proximal fresh tendon stumps are recognized, direct tendon suture is recommended. Wray and Parlin have reported a case of spontaneous flexor tendon rupture in the palm in which a small interposition tendon graft restored normal motion.13 They performed tendon grafting because of the oblique shearing nature of the stump, scarring, and retraction. We also performed tendon grafting, but for a different reason. If the tendon of the little finger is attached at the same position as the torn bifurcation, the tendon bifurcation remains a potential weak point. To reconstruct the tendon to resemble normal anatomy, interposition tendon grafting should be performed with the proximal connection placed proximal to the carpal tunnel. We believe that restoring the normal anatomic configuration reduces shearing stress at the suture point and consequently prevents recurrent tendon rupture.
Figure 4. Postoperative active flexion of the left little finger.
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Figure 5. Cross-sectional magnetic resonance images of the uninjured right hand. (A) The isolated FDP tendon of the little finger (arrow) was recognized at the level of the metacarpophalangeal joint. (B) The FDP tendon of the little finger fused (arrow) at the midpalm. (C) The FDP tendon of the ring finger (arrow) was recognized, but the FDP tendon of the little finger could not be found at the level of the proximal metacarpal.
Received for publication March 2, 2007; accepted in revised form May 17, 2007. No benefits in any form have been received or will be received from a commercial party related directly or indirectly to the subject of this article. Corresponding author: Fujioka Masaki, MD, Department of Plastic and Reconstructive Surgery, National Nagasaki Medical Center, 1001-1 Kubara 2, Ohmura City 856-8562, Japan; e-mail: mfujioka@nmc. hosp.go.jp.
Copyright © 2007 by the American Society for Surgery of the Hand 0363-5023/07/32A08-0011$32.00/0 doi:10.1016/j.jhsa.2007.05.018
References 1. Wilson RL. Rheumatoid arthritis of the hand. Orthop Clin North Am 1986;17:313–343. 2. Hankin F, Mayhew D, Compman R, Snedden M, Schneider
Masaki et al / Spontaneous Flexor Tendon Rupture of the Flexor Digitorum Profundus
3.
4.
5.
6.
7.
LH. Gouty infiltration of a flexor tendon simulating rupture. Clin Orthop Relat Res 1985;194:172–175. Takami H, Takahashi S, Ando M. Attritional flexor tendon ruptures after a malunited intra-articular fracture of the distal radius. Arch Orthop Trauma Surg 1997;116:507–509. Takami H, Takahashi S, Ando M. Rupture of flexor tendon associated with previous fracture of the hook of the hamate. Hand 1983;15:73–76. Masada K, Kawabata H, Ono K. Pathologic rupture of flexor tendons due to longstanding Kienbock’s disease. J Hand Surg 1987;12A:22–25. Imbriglia JE, Goldstein SA. Intratendinous ruptures of the flexor digitorum profundus tendon of the small finger. J Hand Surg 1987;12A:985–991. McLain RF, Steyers C, Blair W. Spontaneous rupture of digital flexor tendons. Orthopedics 1994;17:292–296.
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8. Boyes JH,Wilson JN,Smith JW. Flexor-tendon ruptures in the forearm and hand. J Bone Joint Surg 1960;42A:637– 646. 9. Folmar RC, Nelson CL, Phalen GS. Ruptures of the flexor tendons in hands of non-rheumatoid patients. J Bone Joint Surg 1972;54A:579 –584. 10. Davis C, Armstrong J. Spontaneous flexor tendon rupture in the palm: the role of a variation of tendon anatomy. J Hand Surg 2003;28A:149 –152. 11. Yu HL, Chase RA, Strauch B, eds. Atlas of hand anatomy and clinical implications: extrinsic digital flexors. 1st ed. St. Louis: Mosby, 2004:284 –299. 12. Naam NH. Intratendinous rupture of the flexor digitorum profundus tendon in zones II and III. J Hand Surg 1995;20A: 478 – 483. 13. Wray RC Jr, Parlin LS. Spontaneous flexor tendon rupture in the palm. Ann Plast Surg 1989;23:352–353.
We report a case of the flexor digitorum profundus tendon rupture of the little finger, which was predisposed by an anatomic variation of the tendon. Intraoperative findings and magnetic resonance imaging of the opposite hand suggested that the flexor digitorum profundus tendons of the ring and the little finger bifurcated. The patient had tendon reconstruction and regained function. We believe that reconstructing the tendon so that it resembles the normal anatomy prevents the recurrence of tendon rupture. (J Hand Surg 2007;32A:1195–1199. Copyright © 2007 by the American Society for Surgery of the Hand.) Key words: Flexor digitorum profundus, spontaneous flexor tendon rupture, variation of flexor tendons.
ost reported cases of closed flexor digitorum profundus (FDP) tendon rupture are associated with inflammatory arthritis disorders, such as rheumatoid arthritis and gout. Other cases of flexor tendon rupture in otherwise healthy persons are usually associated with bony abnormalities such as old fractures of carpal bones and the distal radius and Kienböck’s disease.1–5 Excluding such cases with clear causes, most flexor tendon ruptures are caused by avulsion of the FDP from its insertion in the ring finger when an athlete grasps an opponent’s clothing strongly.6 We report an unusual case of spontaneous flexor tendon rupture in the little finger predisposed by an anatomic variation in both hands, which was identified by the intraoperative finding and magnetic resonance imaging finding of the opposite hand.
M
Case Report A 26-year-old man noted the inability to flex his nondominant left little finger at the distal interphalangeal joint (Fig. 1). Two days earlier, he had firmly gripped an opponent’s clothing during a rugby game but sustained no open wound. He had no history of previous hand injury or disease, including inflammatory arthritis. A FDP rupture was diagnosed, and tendon suture was planned for 1 week after injury. Surgical exploration revealed that the distal tendon
Figure 1. Preoperative photograph showing loss of flexion of the left little finger distalinterphalangeal joint.
The Journal of Hand Surgery
1195
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The Journal of Hand Surgery / Vol. 32A No. 8 October 2007
Figure 2. (A) The flexor digitorum profundus (FDP) tendon had ruptured in the midpalm. The stump was oblique. (B) The proximal FDP tendon stump was not found, although the incision was extended to the forearm. FDPIV, flexor digitorum profundus tendon IV; FCU, flexor carpi ulnaris tendon.
stump of the ruptured FDP tendon was at the level of the midpalm (zone 3). The short distal end of the tendon stump was oblique as if it had been torn off, but it showed inflammatory degeneration (Fig. 2A). There was no bony prominence within the palm or carpal tunnel. The proximal FDP tendon stump was not found, although the incision was extended to the forearm (Fig. 2B). The ruptured tendon was reconstructed using a palmaris longus tendon graft. The distal stump suture to the grafted tendon was performed with the interlacing suture technique, and the proximal suture was performed with end-to-side suture of the graft into the FDP tendon of the ring finger. The proximal connection was placed in the forearm to avoid tendon adhesion in zone 2 and the carpal tunnel (Fig. 3). Active mobilization was started 2 weeks later, and the repair was protected by a splint for 6 weeks. Six months after surgery, the patient had active distal interphalangeal joint motion range of 0 to 65 degrees and regained a strong grip and excellent use of the hand (Fig. 4).
Magnetic resonance imaging (MRI) of the opposite hand was performed 1 week after surgery to investigate variations of the FDP tendons. The MRI scan revealed that the FDP tendon of the little finger was not isolated but branched from the FDP of the ring finger at midpalm (Fig. 5).
Discussion Most cases of flexor tendon rupture are associated with rheumatoid arthritis or traumatic or congenital bony abnormalities.1,3–5 Spontaneous flexor tendon rupture without these inflammatory and bony factors is rare. Several investigators have described cases of true spontaneous FDP and flexor pollicis longus tendon ruptures: McLain and Steyer reported 3 cases, Imbriglia and Goldstein reported 10 cases, Boyes et al reported 3 cases, and Folmar et al reported 2 cases.6 –9 The cause of these ruptures, however, remains unclear. It is curious that tendon ruptures occur in the intratendinous portion, because the insertion junction
Masaki et al / Spontaneous Flexor Tendon Rupture of the Flexor Digitorum Profundus
Figure 3. (A) Schematic representation of the FDP tendons. The FDP tendon of the little finger bifurcated from the tendon of the ring finger at midpalm and ruptured at this point. (B) The tendon was reattached to the FDP of the ring finger by interposing a palmaris longus tendon graft proximal to the carpal tunnel.
is the weakest point of the musculotendinous unit. When forceful extension loads the FDP, avulsion of the tendon should occur at its insertion portion. McLain and Steyer have suggested that these intratendinous ruptures result from tendon weakness due to repeated microtrauma or vascular compromise.7 Davis and Armstrong have reported two cases of spontaneous flexor tendon rupture due to tendon variations, which represents a new explanation for tendon rupture.10 Surgical exploration of their 2 cases revealed that the FDP tendon to the ring finger had sheared cleanly off at the level of the superficial palmar arch. We made an identical operative exploration in our case and found neither a proximal FDP tendon stump nor marks of tendon avulsion on the common FDP muscle. The FDP tendons usually arise from a common muscle, and the 2 ulnar FDP tendons tend to originate from the same muscle belly and separate in the forearm or carpal tunnel.11 The magnetic resonance image of the patient’s right hand showed a variant of the FDP little finger tendon in which the tendons of the little and ring finger appeared to be fused side-to-side at the midpalmar level. The tendons of the left hand might have had the same variation. When the pulling stress loaded the little finger, the tendon bifurcation, which was the weakest point against shearing forces, tore and ruptured. We believe that this anatomic anomaly predisposed to FDP tendon rupture. Suggested methods for surgical reconstruction include direct repair, tendon grafting, and tendon transfer. Results are believed to depend primarily on the
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time since rupture and the location of the injury. Naam reported surgical results of 13 patients with spontaneous FDP tendon rupture: 7 patients had direct repair, 5 had tendon grafting, and 1 had tendon transfer. He concluded that patients who had early direct repair had better functional results than those who were treated with tendon grafting or tendon transfer.12 McLain et al have also concluded that the results of direct repair within 1 week of rupture are superior to the results of late reconstruction.7 If both the distal and proximal fresh tendon stumps are recognized, direct tendon suture is recommended. Wray and Parlin have reported a case of spontaneous flexor tendon rupture in the palm in which a small interposition tendon graft restored normal motion.13 They performed tendon grafting because of the oblique shearing nature of the stump, scarring, and retraction. We also performed tendon grafting, but for a different reason. If the tendon of the little finger is attached at the same position as the torn bifurcation, the tendon bifurcation remains a potential weak point. To reconstruct the tendon to resemble normal anatomy, interposition tendon grafting should be performed with the proximal connection placed proximal to the carpal tunnel. We believe that restoring the normal anatomic configuration reduces shearing stress at the suture point and consequently prevents recurrent tendon rupture.
Figure 4. Postoperative active flexion of the left little finger.
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Figure 5. Cross-sectional magnetic resonance images of the uninjured right hand. (A) The isolated FDP tendon of the little finger (arrow) was recognized at the level of the metacarpophalangeal joint. (B) The FDP tendon of the little finger fused (arrow) at the midpalm. (C) The FDP tendon of the ring finger (arrow) was recognized, but the FDP tendon of the little finger could not be found at the level of the proximal metacarpal.
Received for publication March 2, 2007; accepted in revised form May 17, 2007. No benefits in any form have been received or will be received from a commercial party related directly or indirectly to the subject of this article. Corresponding author: Fujioka Masaki, MD, Department of Plastic and Reconstructive Surgery, National Nagasaki Medical Center, 1001-1 Kubara 2, Ohmura City 856-8562, Japan; e-mail: mfujioka@nmc. hosp.go.jp.
Copyright © 2007 by the American Society for Surgery of the Hand 0363-5023/07/32A08-0011$32.00/0 doi:10.1016/j.jhsa.2007.05.018
References 1. Wilson RL. Rheumatoid arthritis of the hand. Orthop Clin North Am 1986;17:313–343. 2. Hankin F, Mayhew D, Compman R, Snedden M, Schneider
Masaki et al / Spontaneous Flexor Tendon Rupture of the Flexor Digitorum Profundus
3.
4.
5.
6.
7.
LH. Gouty infiltration of a flexor tendon simulating rupture. Clin Orthop Relat Res 1985;194:172–175. Takami H, Takahashi S, Ando M. Attritional flexor tendon ruptures after a malunited intra-articular fracture of the distal radius. Arch Orthop Trauma Surg 1997;116:507–509. Takami H, Takahashi S, Ando M. Rupture of flexor tendon associated with previous fracture of the hook of the hamate. Hand 1983;15:73–76. Masada K, Kawabata H, Ono K. Pathologic rupture of flexor tendons due to longstanding Kienbock’s disease. J Hand Surg 1987;12A:22–25. Imbriglia JE, Goldstein SA. Intratendinous ruptures of the flexor digitorum profundus tendon of the small finger. J Hand Surg 1987;12A:985–991. McLain RF, Steyers C, Blair W. Spontaneous rupture of digital flexor tendons. Orthopedics 1994;17:292–296.
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8. Boyes JH,Wilson JN,Smith JW. Flexor-tendon ruptures in the forearm and hand. J Bone Joint Surg 1960;42A:637– 646. 9. Folmar RC, Nelson CL, Phalen GS. Ruptures of the flexor tendons in hands of non-rheumatoid patients. J Bone Joint Surg 1972;54A:579 –584. 10. Davis C, Armstrong J. Spontaneous flexor tendon rupture in the palm: the role of a variation of tendon anatomy. J Hand Surg 2003;28A:149 –152. 11. Yu HL, Chase RA, Strauch B, eds. Atlas of hand anatomy and clinical implications: extrinsic digital flexors. 1st ed. St. Louis: Mosby, 2004:284 –299. 12. Naam NH. Intratendinous rupture of the flexor digitorum profundus tendon in zones II and III. J Hand Surg 1995;20A: 478 – 483. 13. Wray RC Jr, Parlin LS. Spontaneous flexor tendon rupture in the palm. Ann Plast Surg 1989;23:352–353.