- Email: [email protected]
Useful MRI assessment for bowstringing of the flexor tendon after trigger finger release
J Orthop Sci DOI 10.1007/s00776-012-0264-2
CASE REPORT
Useful MRI assessment for bowstringing of the flexor tendon after trigger finger release Naoki Kato • Takahiro Yoshizawa Hiroya Sakai
•
Received: 26 December 2011 / Accepted: 1 June 2012 Ó The Japanese Orthopaedic Association 2012
Introduction Bowstringing of the flexor tendon because of inadvertent disruption of the A2 pulley has been routinely described as a complication after the release of trigger fingers. In this report, we present two cases of bowstringing of the flexor tendon after release of trigger fingers. In both cases, magnetic resonance imaging (MRI) with the finger in flexion was useful for definitive diagnosis, and reconstruction of the A2 pulley by the double loop technique using the palmaris longus (PL) tendon resulted in satisfactory outcome.
Case 1 A 72-year-old right-hand-dominant male with no history of trauma or inflammatory arthritis presented with persistent pain and reduced active range of motion of his right middle finger 2 years after trigger finger release performed at another hospital. Although no joint contracture could be observed by passive range of motion, the active range of motion of the metacarpophalangeal (MCP), proximal interphalangeal (PIP), and distal interphalangeal (DIP) joints was -15° to 85°, 0° to 80°, and 0° to 60°, respectively. Triggering was absent and clinical examination showed that both flexor tendons were intact. Grip strength of his right hand was 17.1 kg and that of his left hand was 21.1 kg. Flexor tendon bowstringing was present on the
N. Kato (&) T. Yoshizawa H. Sakai Department of Orthopaedic Surgery, Saitama Medical Center, Saitama Medical University, 1981 Kamoda, Kawagoe, Saitama 350-8550, Japan e-mail: [email protected]
palmar aspect of his right middle finger and on the palm at the time of flexion (Fig. 1). For definitive diagnosis, MRI was performed with his fingers in full flexion. We asked him to grasp the hand touching the palm with pulp of his fingers and to maintain this finger position during the examination. In this case, it was impossible to touch his palm with his right middle finger due to reduced active range of motion, therefore we asked him to flex his fingers as much as possible. This MRI clearly revealed that the A2 pulley of his middle finger was compromised and the flexor tendon displaced in a palmar direction at the base of proximal phalanx (Fig. 2). A pulley reconstruction using palmaris longus (PL) tendon autograft was performed to restore mechanical efficiency under general anaesthesia. On exploration, only a small distal portion of the A2 pulley remained and mild adhesion between the flexor digitorum profundus (FDP) and superficialis (FDS) could be observed. Bowstringing of the flexor tendon was prominent when the flexor was towed proximally (Fig. 3). A looped 2-0 non-absorbable polyester suture was passed between the extensor mechanism and the dorsum of the proximal phalanx to aid PL tendon passage. The PL tendon was passed twice and then secured to itself and to the remaining lateral elements of the pulley by use of a 4-0 non-absorbable polyester suture with horizontal mattress stitches, just distal to the MCP joint. Finally, when the reconstructed pulley was tested by pulling on the flexor tendons in the proximal part of the wound, no bowstringing of the flexor tendon could be observed. The MCP joint of the middle finger was immobilized in full extension by use of a plaster splint and he was allowed to begin range of motion exercises without undue stress on the reconstructed pulley. The patient was instructed to wear this plaster splint at all times for 3 weeks. At 6 months after the operation, the active range of motion of the MCP, PIP, and DIP joints
123
N. Kato et al.
Fig. 1 Flexor tendon bowstringing was present on the palmar aspect of his right middle finger and on the palm at the time of flexion (arrow indicates bowstringing of the flexor tendon)
Fig. 4 The A2 pulley was compromised and the flexor tendon displaced in a palmar direction. In addition, fluid retention could be observed along the flexor tendon sheath (arrow indicates the flexor tendon, asterisk indicates the fluid retention)
was 0°–90°, 0°–100° and 0°–70°, respectively, with equal grip strength in both hands. He had returned to his activities without any problem.
Case 2
Fig. 2 A2 pulley of his middle finger was compromised and the flexor tendon displaced in a palmar direction (arrow indicates the flexor tendon)
Fig. 3 Bowstringing of the flexor tendon was prominent when the flexor was towed proximally (arrow indicates the flexor tendon)
123
A 58-year-old right-hand-dominant female with no history of trauma or inflammatory arthritis presented with persistent pain and swelling of her right middle finger 6 months after trigger finger release performed at another hospital. No joint contracture could be observed by passive range of motion, and the active range of motion of the MCP, PIP, and DIP joints was 0°–85°, 0°–85° and 0°–60°, respectively. A cord-like mass could be observed on her right palm along the flexor tendon of the middle finger and this became more obvious at the time of finger flexion. MRI performed with her fingers in full flexion revealed the A2 pulley was compromised and the flexor tendon displaced in a palmar direction. In addition, fluid retention could be observed along the flexor tendon sheath (Fig. 4). We diagnosed bowstringing of the flexor tendon but also suspected chronic infectious tenosynovitis of the tendon sheath. Therefore, at the beginning of the exploration, we performed rapid bacteriological examination but found no infection. During the operation, it became clear that A2 pulley was almost absent. In addition, severe tenosynovitis around the flexor tendon with adhesion between FDP and FDS could be observed. We performed synovectomy thoroughly and a double loop pulley reconstruction using the PL tendon was performed by the method described in case 1. The MCP joint of the middle finger was immobilized in full extension by use of a plaster splint for 3 weeks.
Bowstringing after trigger release
At 8 months after the operation, pain and swelling of her right middle finger had completely disappeared and the active range of motion of the MCP, PIP, and DIP joints was 0°–85°, 0°–90° and 0°–80°, respectively. She was extremely satisfied with the outcome and had returned to her activities as a professional nurse without any problem.
Discussion The flexor tendon pulley system is uniquely designed to efficiently transmit tendon excursion into angular range of motion of all three finger joints. This system is crucially important in keeping the flexor tendons closely applied to the volar aspect of the phalanges. Without their normal function, the tendons are displaced in a palmar direction and travel the shortest distance between adjacent remaining pulleys. It is well known that loss of all or part of the flexor tendon pulley system may have a significant effect on digital performance [1]. Doyle [2] studied 61 fingers anatomically and reported that a distinct separation between the A1 and A2 pulleys was found in 58 fingers (95 %) and that this separation ranged from 0.4 to 4.1 mm. Strauch and de Moura [3], in a recent study, concluded that in most cases (65 %) there was no separation between the A1 and A2 pulleys. We presume that these different configurations and segmental arrangement of the A1 pulley and the A2 pulley might be one of the reasons for advertent disruption of the A2 pulley during trigger release surgery. Although bowstringing of the flexor tendon is regarded as a rare complication of trigger finger release, prolonged bowstringing can lead to serious clinical problems including loss of grip power and the development of fixed flexion contracture. In this respect, early diagnosis to prevent the development of digit dysfunction is critical. Erickson et al. [4] state that visualization of the pulley by MRI is inconstant. In normal MRI with the fingers in extension, the pulley appears as a thin low-signal structure that surrounds the flexor tendon. We used MRI not to detect the A2 pulley itself, but to examine the mechanical effectiveness of the A2 pulley. For this purpose, MRI obtained with the fingers in flexion was helpful for definitive diagnosis. We confirmed bowstringing of the flexor tendon and severe tenosynovitis around the flexor as detected by MRI during the operation. Recently, high-resolution ultrasonography has gained a significant place in the clinical field because of its advantages (convenient, inexpensive, non-invasive). Although we have not applied this before, it would be also a valuable tool for detection of bowstringing of the flexor tendon. Previously, a variety of materials and surgical techniques have been used for the A2 pulley reconstruction. The site of the reconstructed pulley is of utmost importance
to its mechanical efficiency. It has been reported that the pulley should be reconstructed at the base of the proximal phalanx [5]. The different materials include remnants of the old pulley system, the scarred tendon, or material from a distance, for example free tendon graft or extensor retinaculum [6–8]. In respect of the surgical techniques, weaving a tendon graft through the lateral remnants of the original pulley [7], the volar plate method [6], and the loop method, as in our cases, have been reported [9]. A cadaver study revealed the volar plate method was the most mechanically effective and the encircling technique was the strongest [8], however, this technique can be used only in two-stage flexor tendon grafting, and is not applicable to preventing bowstringing of the flexor tendons after trigger release. Concerned with the biomechanics of pulley reconstruction methods, Lin et al. [10] reported that the strength of a pulley reconstructed by the triple-loop method was approximately equal to that of a normal pulley, and that the double-loop method could be regarded as strong enough for early active protected motion. Given that we confirmed an A2 pulley reconstructed by use of the double-loop method seemed to have adequate width for preventing bowstringing of the flexor tendon, and that wider reconstructions with the triple-loop technique might have the potential for tendon blood supply compromise [9], we applied the double-loop method considering that this method might be a reasonable compromise between pulley strength and tendon nutrition. Conflict of interest All the named authors hereby declare they have no conflicts of interest to disclose.
References 1. Boyes JH, Stark HH. Flexor tendon grafts in the finger and thumb: a study of factors influencing results in 1000 cases. J Bone Joint Surg. 1971;53A:1332–42. 2. Doyle JR. Anatomy of the finger flexor tendon sheath and pulley system. J Hand Surg. 1988;13A:473–84. 3. Strauch B, de Moura W. Digital flexor tendon sheath: an anatomic study. J Hand Surg. 1985;10A:785–9. 4. Erickson SJ, Kneeland B, Middleton WD, Jesmanowicz A, Hyde J, Lawson TL, et al. MR imaging of the finger: correlation with normal anatomic sections. Am J Roentgenol. 1989;152:1013–9. 5. Hume EL, Hutchinson DT, Jaeger SA, Hunter JM. Biomechanics of pulley reconstruction. J Hand Surg. 1991;16A:722–30. 6. Karev A, Stahl S, Taran A. The mechanical efficiency of the pulley system in normal digits compared with a reconstructed system using the ‘‘belt loop’’ technique. J Hand Surg. 1987;12A:596–601. 7. Kleinert HE, Bennett JB. Digital pulley reconstruction employing the always present rim of the previous pulley. J Hand Surg. 1978; 3A:297–8. 8. Widstrom CJ, Johnson G, Doyle JR, Manske PR, Inhofe P. A mechanical study of six digit pulley reconstruction techniques: part I. Mechanical effectiveness. J Hand Surg. 1989;14A:821–5.
123
N. Kato et al. 9. Okutsu I, Ninomiya S, Hiraki S, Inanami H, Kuroshima N. Threeloop technique for A2 pulley reconstruction. J Hand Surg. 1987; 12A:790–4.
123
10. Lin GT, Amadio PC, An KN, Cooney WP, Chao EY. Biomechanical analysis of finger flexor pulley reconstruction. J Hand Surg. 1989;14B:278–82.
CASE REPORT
Useful MRI assessment for bowstringing of the flexor tendon after trigger finger release Naoki Kato • Takahiro Yoshizawa Hiroya Sakai
•
Received: 26 December 2011 / Accepted: 1 June 2012 Ó The Japanese Orthopaedic Association 2012
Introduction Bowstringing of the flexor tendon because of inadvertent disruption of the A2 pulley has been routinely described as a complication after the release of trigger fingers. In this report, we present two cases of bowstringing of the flexor tendon after release of trigger fingers. In both cases, magnetic resonance imaging (MRI) with the finger in flexion was useful for definitive diagnosis, and reconstruction of the A2 pulley by the double loop technique using the palmaris longus (PL) tendon resulted in satisfactory outcome.
Case 1 A 72-year-old right-hand-dominant male with no history of trauma or inflammatory arthritis presented with persistent pain and reduced active range of motion of his right middle finger 2 years after trigger finger release performed at another hospital. Although no joint contracture could be observed by passive range of motion, the active range of motion of the metacarpophalangeal (MCP), proximal interphalangeal (PIP), and distal interphalangeal (DIP) joints was -15° to 85°, 0° to 80°, and 0° to 60°, respectively. Triggering was absent and clinical examination showed that both flexor tendons were intact. Grip strength of his right hand was 17.1 kg and that of his left hand was 21.1 kg. Flexor tendon bowstringing was present on the
N. Kato (&) T. Yoshizawa H. Sakai Department of Orthopaedic Surgery, Saitama Medical Center, Saitama Medical University, 1981 Kamoda, Kawagoe, Saitama 350-8550, Japan e-mail: [email protected]
palmar aspect of his right middle finger and on the palm at the time of flexion (Fig. 1). For definitive diagnosis, MRI was performed with his fingers in full flexion. We asked him to grasp the hand touching the palm with pulp of his fingers and to maintain this finger position during the examination. In this case, it was impossible to touch his palm with his right middle finger due to reduced active range of motion, therefore we asked him to flex his fingers as much as possible. This MRI clearly revealed that the A2 pulley of his middle finger was compromised and the flexor tendon displaced in a palmar direction at the base of proximal phalanx (Fig. 2). A pulley reconstruction using palmaris longus (PL) tendon autograft was performed to restore mechanical efficiency under general anaesthesia. On exploration, only a small distal portion of the A2 pulley remained and mild adhesion between the flexor digitorum profundus (FDP) and superficialis (FDS) could be observed. Bowstringing of the flexor tendon was prominent when the flexor was towed proximally (Fig. 3). A looped 2-0 non-absorbable polyester suture was passed between the extensor mechanism and the dorsum of the proximal phalanx to aid PL tendon passage. The PL tendon was passed twice and then secured to itself and to the remaining lateral elements of the pulley by use of a 4-0 non-absorbable polyester suture with horizontal mattress stitches, just distal to the MCP joint. Finally, when the reconstructed pulley was tested by pulling on the flexor tendons in the proximal part of the wound, no bowstringing of the flexor tendon could be observed. The MCP joint of the middle finger was immobilized in full extension by use of a plaster splint and he was allowed to begin range of motion exercises without undue stress on the reconstructed pulley. The patient was instructed to wear this plaster splint at all times for 3 weeks. At 6 months after the operation, the active range of motion of the MCP, PIP, and DIP joints
123
N. Kato et al.
Fig. 1 Flexor tendon bowstringing was present on the palmar aspect of his right middle finger and on the palm at the time of flexion (arrow indicates bowstringing of the flexor tendon)
Fig. 4 The A2 pulley was compromised and the flexor tendon displaced in a palmar direction. In addition, fluid retention could be observed along the flexor tendon sheath (arrow indicates the flexor tendon, asterisk indicates the fluid retention)
was 0°–90°, 0°–100° and 0°–70°, respectively, with equal grip strength in both hands. He had returned to his activities without any problem.
Case 2
Fig. 2 A2 pulley of his middle finger was compromised and the flexor tendon displaced in a palmar direction (arrow indicates the flexor tendon)
Fig. 3 Bowstringing of the flexor tendon was prominent when the flexor was towed proximally (arrow indicates the flexor tendon)
123
A 58-year-old right-hand-dominant female with no history of trauma or inflammatory arthritis presented with persistent pain and swelling of her right middle finger 6 months after trigger finger release performed at another hospital. No joint contracture could be observed by passive range of motion, and the active range of motion of the MCP, PIP, and DIP joints was 0°–85°, 0°–85° and 0°–60°, respectively. A cord-like mass could be observed on her right palm along the flexor tendon of the middle finger and this became more obvious at the time of finger flexion. MRI performed with her fingers in full flexion revealed the A2 pulley was compromised and the flexor tendon displaced in a palmar direction. In addition, fluid retention could be observed along the flexor tendon sheath (Fig. 4). We diagnosed bowstringing of the flexor tendon but also suspected chronic infectious tenosynovitis of the tendon sheath. Therefore, at the beginning of the exploration, we performed rapid bacteriological examination but found no infection. During the operation, it became clear that A2 pulley was almost absent. In addition, severe tenosynovitis around the flexor tendon with adhesion between FDP and FDS could be observed. We performed synovectomy thoroughly and a double loop pulley reconstruction using the PL tendon was performed by the method described in case 1. The MCP joint of the middle finger was immobilized in full extension by use of a plaster splint for 3 weeks.
Bowstringing after trigger release
At 8 months after the operation, pain and swelling of her right middle finger had completely disappeared and the active range of motion of the MCP, PIP, and DIP joints was 0°–85°, 0°–90° and 0°–80°, respectively. She was extremely satisfied with the outcome and had returned to her activities as a professional nurse without any problem.
Discussion The flexor tendon pulley system is uniquely designed to efficiently transmit tendon excursion into angular range of motion of all three finger joints. This system is crucially important in keeping the flexor tendons closely applied to the volar aspect of the phalanges. Without their normal function, the tendons are displaced in a palmar direction and travel the shortest distance between adjacent remaining pulleys. It is well known that loss of all or part of the flexor tendon pulley system may have a significant effect on digital performance [1]. Doyle [2] studied 61 fingers anatomically and reported that a distinct separation between the A1 and A2 pulleys was found in 58 fingers (95 %) and that this separation ranged from 0.4 to 4.1 mm. Strauch and de Moura [3], in a recent study, concluded that in most cases (65 %) there was no separation between the A1 and A2 pulleys. We presume that these different configurations and segmental arrangement of the A1 pulley and the A2 pulley might be one of the reasons for advertent disruption of the A2 pulley during trigger release surgery. Although bowstringing of the flexor tendon is regarded as a rare complication of trigger finger release, prolonged bowstringing can lead to serious clinical problems including loss of grip power and the development of fixed flexion contracture. In this respect, early diagnosis to prevent the development of digit dysfunction is critical. Erickson et al. [4] state that visualization of the pulley by MRI is inconstant. In normal MRI with the fingers in extension, the pulley appears as a thin low-signal structure that surrounds the flexor tendon. We used MRI not to detect the A2 pulley itself, but to examine the mechanical effectiveness of the A2 pulley. For this purpose, MRI obtained with the fingers in flexion was helpful for definitive diagnosis. We confirmed bowstringing of the flexor tendon and severe tenosynovitis around the flexor as detected by MRI during the operation. Recently, high-resolution ultrasonography has gained a significant place in the clinical field because of its advantages (convenient, inexpensive, non-invasive). Although we have not applied this before, it would be also a valuable tool for detection of bowstringing of the flexor tendon. Previously, a variety of materials and surgical techniques have been used for the A2 pulley reconstruction. The site of the reconstructed pulley is of utmost importance
to its mechanical efficiency. It has been reported that the pulley should be reconstructed at the base of the proximal phalanx [5]. The different materials include remnants of the old pulley system, the scarred tendon, or material from a distance, for example free tendon graft or extensor retinaculum [6–8]. In respect of the surgical techniques, weaving a tendon graft through the lateral remnants of the original pulley [7], the volar plate method [6], and the loop method, as in our cases, have been reported [9]. A cadaver study revealed the volar plate method was the most mechanically effective and the encircling technique was the strongest [8], however, this technique can be used only in two-stage flexor tendon grafting, and is not applicable to preventing bowstringing of the flexor tendons after trigger release. Concerned with the biomechanics of pulley reconstruction methods, Lin et al. [10] reported that the strength of a pulley reconstructed by the triple-loop method was approximately equal to that of a normal pulley, and that the double-loop method could be regarded as strong enough for early active protected motion. Given that we confirmed an A2 pulley reconstructed by use of the double-loop method seemed to have adequate width for preventing bowstringing of the flexor tendon, and that wider reconstructions with the triple-loop technique might have the potential for tendon blood supply compromise [9], we applied the double-loop method considering that this method might be a reasonable compromise between pulley strength and tendon nutrition. Conflict of interest All the named authors hereby declare they have no conflicts of interest to disclose.
References 1. Boyes JH, Stark HH. Flexor tendon grafts in the finger and thumb: a study of factors influencing results in 1000 cases. J Bone Joint Surg. 1971;53A:1332–42. 2. Doyle JR. Anatomy of the finger flexor tendon sheath and pulley system. J Hand Surg. 1988;13A:473–84. 3. Strauch B, de Moura W. Digital flexor tendon sheath: an anatomic study. J Hand Surg. 1985;10A:785–9. 4. Erickson SJ, Kneeland B, Middleton WD, Jesmanowicz A, Hyde J, Lawson TL, et al. MR imaging of the finger: correlation with normal anatomic sections. Am J Roentgenol. 1989;152:1013–9. 5. Hume EL, Hutchinson DT, Jaeger SA, Hunter JM. Biomechanics of pulley reconstruction. J Hand Surg. 1991;16A:722–30. 6. Karev A, Stahl S, Taran A. The mechanical efficiency of the pulley system in normal digits compared with a reconstructed system using the ‘‘belt loop’’ technique. J Hand Surg. 1987;12A:596–601. 7. Kleinert HE, Bennett JB. Digital pulley reconstruction employing the always present rim of the previous pulley. J Hand Surg. 1978; 3A:297–8. 8. Widstrom CJ, Johnson G, Doyle JR, Manske PR, Inhofe P. A mechanical study of six digit pulley reconstruction techniques: part I. Mechanical effectiveness. J Hand Surg. 1989;14A:821–5.
123
N. Kato et al. 9. Okutsu I, Ninomiya S, Hiraki S, Inanami H, Kuroshima N. Threeloop technique for A2 pulley reconstruction. J Hand Surg. 1987; 12A:790–4.
123
10. Lin GT, Amadio PC, An KN, Cooney WP, Chao EY. Biomechanical analysis of finger flexor pulley reconstruction. J Hand Surg. 1989;14B:278–82.