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Independent function in a split flexor carpi radialis transfer 1
Independent Function in a Split Flexor Carpi Radialis Transfer Aymeric YT Lim, MD, Amitabha Lahiri, MCh, Barry P. Pereira, MEng, V. Prem Kumar, MD, Lay-Lay Tan, BSc, Singapore
In a patient requiring tendon transfer after radial nerve palsy, the flexor carpi radialis, a bipennate muscle, was split longitudinally into 2 compartments along the length of the aponeurosis extending proximally from the distal tendon to provide independent finger and thumb extension. This case report shows that the 2 compartments of a bipennate muscle in the forearm may have separate innervation, allowing transfer for independent functions. (J Hand Surg 2004;29A:28 –31. Copyright © 2004 by the American Society for Surgery of the Hand.) Key words: Split tendon transfer, bipennate muscle, radial palsy.
The flexor carpi radialis (FCR) is a bipennate muscle with 2 neuromuscular compartments (Fig. 1). A previous anatomic study1 has established that this muscle is suitable for splitting with the aim of providing independent function in each muscle compartment. This case report describes a successful split FCR transfer in the context of a tendon transfer for radial nerve palsy.
Case Report A 49-year-old right-handed electrician was flung off his motorcycle and sustained a grade II open comminuted midshaft fracture of the left humerus associated with radial nerve palsy. The humeral fracture with radial nerve palsy had surgical exploration. Intraoperatively, we observed a 3-cm segmental loss of From the Department of Hand and Reconstructive Microsurgery, National University Hospital; Department of Orthopaedic Surgery, National University of Singapore; and Department of Rehabilitation, National University Hospital, Singapore. Received for publication April 29, 2003; accepted in revised form September 4, 2003. No benefits in any form have been received or will be received by a commercial party related directly or indirectly to the subject of this article. Reprint requests: Dr. Aymeric YT Lim, Consultant, Department of Hand & Reconstructive Microsurgery, National University Hospital, 5 Lower Kent Ridge Rd, Singapore 119074. Copyright © 2004 by the American Society for Surgery of the Hand 0363-5023/04/29A01-0005$30.00/0 doi:10.1016/jhsa.2003.09.011
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The Journal of Hand Surgery
the radial nerve. The fracture was fixed with a 7-hole broad dynamic compression plate and the continuity of the radial nerve was restored with a sural nerve graft. Six months later there was no recovery of the radial nerve, Tinel’s sign was static at the level of the midhumeral shaft, and there was no motor function in the muscles innervated by the radial nerve. In view of the patient’s age and the length of time after the original injury we decided to perform tendon transfers as described by Starr2 in 1922. After making a volar incision for tendon transfer we noted the palmaris longus muscle was noted to be atrophic. We proceeded to do a split FCR transfer. The insertion of the FCR tendon was divided and by applying tension to the cut end, the muscle was split into 2 compartments along the tendon and the aponeurosis all the way to its proximal fifth as described previously (Fig. 2).1 Care was taken not to divide the separate vascular and nerve pedicles entering each compartment. The smaller ulnar-sided tendon was passed radially and subcutaneously and woven into the extensor pollicis longus tendon while the radial tendon was passed dorsally and woven into the tendons of the extensor digitorum communis. The pronator teres was similarly sutured to the extensor carpi radialis brevis. Tensioning of the transfers was performed with the wrist and metacarpophalangeal joints in neutral and both heads of the FCR stretched.
Lim et al / Independent Function in a Split FCR Transfer
29
Figure 2. FCR is split into an ulnar compartment and a radial compartment before transfer, preserving the proximal fifth of the muscle.
A splint was applied to hold the wrist extended 45° distally to the maximum length, the metacarpophalangeal joints at 10° of flexion, and the interphalangeal joints were extended. Active movements were started 3 weeks after surgery. A rehabilitation program with emphasis on separating extensor pollicis longus and extensor digitorum communis function was instituted at the end of the 3-week period. At 6 months after surgery the patient was able to flex his thumb while extending his fingers and conversely extend his thumb while flexing his fingers (Fig. 3)
Discussion Muscle–tendon units can be split for a variety of reasons. In the lower limb, the tibialis posterior is Figure 1. Sketch showing the anatomy of human FCR based on the findings after Sihler’s staining of the FCR. (T) represents the tendon of FCR that extends to the proximal third of the muscle as an aponeurosis that divides the muscle into a radial compartment (R) and an ulnar compartment (U). The pronator teres (P) is retracted to show the median nerve (M). The median nerve gives out a muscular branch (Br) to the
4™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™ FCR, which enters the muscle in the proximally. As it enters it divides into branches (a), (b), and (c). Branch (a) supplies the radial compartment, whereas the branch (b) supplies the ulnar compartment. Branch (c) supplies fibers in the proximal third of the muscle.
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The Journal of Hand Surgery / Vol. 29A No. 1 January 2004
Figure 3. The function of the thumb and digits at 6 months after the split FCR transfer. (A) Active finger extension and thumb flexion showed the independent contraction of the radial compartment of the FCR to the extensor digitorum communis, with simultaneous relaxation of the ulnar compartment transferred to the extensor pollicis longus, and (B) active thumb extension and finger flexion showing the independent action of the ulnar compartment of the FCR to the extensor pollicis longus with simultaneous relaxation of the radial compartment transferred to the extensor digitorum communis.
often split to balance the foot in both equinovarus deformity and in cerebral palsy.3 In the upper limb the flexor digitorum superficialis tendons to the long and ring fingers have been used to restore extension of the thumb and the digits, respectively, in radial nerve palsy.2 Split abductor pollicis longus tendon and muscle have been used to restore the function of the thumb in cases of ruptured extensor pollicis longus.4 The flexor pollicis longus has been split to provide stability at the interphalangeal joint of the thumb in patients with tetraplegia.5 Most of the actions in the above transfers, however, are synergistic to the action of the muscle being split or act in conjunction with the other actions of the muscle to the digit that received the transfer. Manktelow and Zuker 6 observed that the gracilis has separately innervated motor territories that may contract independently. Parts of the gracilis were used for facial reanimation and Manktelow and Zuker also suggested splitting this muscle into functioning neuromuscular territories. We previously reported independent function in a split transfer of the flexor carpi ulnaris7,8 and have now applied the technique to the FCR muscle. A muscle that is ideal for splitting would have the
following characteristics. The tendon of insertion should have an aponeurosis that extends proximally within the muscle, which allows easy and accurate division in the intercompartmental plane up to the proximal limit, facilitating anatomic and functional separation of the compartments. It is also vital that the nerve and blood supplies to each compartment are independent. Bipennate muscles have this muscle form, and in the forearm, the flexor carpi ulnaris and FCR have been identified as good candidates for split muscle transfers.1,8 Another criterion for split-muscle transfer is that the compartments should also have an adequate physiologic cross-sectional area and fibers length to ensure that they function effectively after transfer.9,10,11 In the case of the FCR, previous work has shown a separate nerve branch from the median nerve to each compartment of the FCR and also an adequate vascular supply to each compartment.1 The muscle architecture has been previously reported to be adequate, with the physiologic crosssectional area and fiber length of the ulnar compartment of the FCR matching those of the extensor pollicis longus, and the physiologic cross-sectional
Lim et al / Independent Function in a Split FCR Transfer
area and fiber length of the radial compartment of the FCR matching those of the extensor digitorum communis.1,8 Splitting the FCR allowed us to perform the transfer in the absence of an adequately functioning palmaris longus. If present, the palmaris longus muscle may also be transferred to restore the function of the abductor pollicis longus for a more complete reconstruction of the thumb. Besides the reconstruction described here, a split FCR transfer may also be used in the group 5 tetraplegic patient.1 Leaving the radial compartment in situ to preserve wrist flexion, the split ulnar compartment of the FCR could be used as a transfer alone to restore thumb opposition. This would provide a quantum improvement in hand function in these severely disabled patients when combined with an extensor carpi radialis longus transfer to the long finger flexors.
References 1. Hua J, Kumar VP, Pereira BP, Lim AYT, Pho RWH, Liu J. Split flexor carpi radialis muscle. Plast Reconstr Surg 1999; 103:930 –934.
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2. Starr CL. Army experiences with tendon transference. J Bone Joint Surg Am 1922;3:3–21. 3. Kling TF Jr, Kaufer H, Hensinger RN. Split posterior tibialtendon transfers in children with cerebral spastic paralysis and equinovarus deformity. J Bone Joint Surg Am 1985;67: 186 –194. 4. Gelb RI. Tendon transfer for rupture of the extensor pollicis longus. Hand Clin 1995;11:411– 422. 5. Mohammed KD, Rothwell AG, Sinclair SW, Willems SM, Bean AR. Upper-limb surgery for tetraplegia. J Bone Joint Surg Br 1992;74:873– 879. 6. Manktelow RT, Zuker RM. Muscle transplantation by fascicular territory. Plast Reconstr Surg 1984;73:751–757. 7. Lim AYT, Kumar VP, Pereira BP, Hua J. Independent function in a tendon transfer of the split flexor carpi ulnaris. Plast Reconstr Surg 1999;104:1739 –1741. 8. Lim AYT, Kumar VP, Hua J, Pereira BP, Pho RWH. The neuromuscular compartments of the flexor carpi ulnaris. Plast Reconstr Surg 1999;103:1046 –1051. 9. Lieber RL, Jacobson MD, Fazeli BM, Abrams RA, Botte MJ. Architecture of selected muscles of the arm and forearm: anatomy and implications for tendon transfer. J Hand Surg 1992;17A:787–798. 10. Lieber RL, Fride´ n J. Clinical significance of skeletal muscle architecture. Clin Orthop 2001;383:140 –151. 11. Brand PW, Hollister A. Mechanics of individual muscles at individual joints. In: Brand PW, Hollister A, eds. Clinical mechanics of the hand. St Louis: Mosby Year Book, 1992: 254 –352.
In a patient requiring tendon transfer after radial nerve palsy, the flexor carpi radialis, a bipennate muscle, was split longitudinally into 2 compartments along the length of the aponeurosis extending proximally from the distal tendon to provide independent finger and thumb extension. This case report shows that the 2 compartments of a bipennate muscle in the forearm may have separate innervation, allowing transfer for independent functions. (J Hand Surg 2004;29A:28 –31. Copyright © 2004 by the American Society for Surgery of the Hand.) Key words: Split tendon transfer, bipennate muscle, radial palsy.
The flexor carpi radialis (FCR) is a bipennate muscle with 2 neuromuscular compartments (Fig. 1). A previous anatomic study1 has established that this muscle is suitable for splitting with the aim of providing independent function in each muscle compartment. This case report describes a successful split FCR transfer in the context of a tendon transfer for radial nerve palsy.
Case Report A 49-year-old right-handed electrician was flung off his motorcycle and sustained a grade II open comminuted midshaft fracture of the left humerus associated with radial nerve palsy. The humeral fracture with radial nerve palsy had surgical exploration. Intraoperatively, we observed a 3-cm segmental loss of From the Department of Hand and Reconstructive Microsurgery, National University Hospital; Department of Orthopaedic Surgery, National University of Singapore; and Department of Rehabilitation, National University Hospital, Singapore. Received for publication April 29, 2003; accepted in revised form September 4, 2003. No benefits in any form have been received or will be received by a commercial party related directly or indirectly to the subject of this article. Reprint requests: Dr. Aymeric YT Lim, Consultant, Department of Hand & Reconstructive Microsurgery, National University Hospital, 5 Lower Kent Ridge Rd, Singapore 119074. Copyright © 2004 by the American Society for Surgery of the Hand 0363-5023/04/29A01-0005$30.00/0 doi:10.1016/jhsa.2003.09.011
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The Journal of Hand Surgery
the radial nerve. The fracture was fixed with a 7-hole broad dynamic compression plate and the continuity of the radial nerve was restored with a sural nerve graft. Six months later there was no recovery of the radial nerve, Tinel’s sign was static at the level of the midhumeral shaft, and there was no motor function in the muscles innervated by the radial nerve. In view of the patient’s age and the length of time after the original injury we decided to perform tendon transfers as described by Starr2 in 1922. After making a volar incision for tendon transfer we noted the palmaris longus muscle was noted to be atrophic. We proceeded to do a split FCR transfer. The insertion of the FCR tendon was divided and by applying tension to the cut end, the muscle was split into 2 compartments along the tendon and the aponeurosis all the way to its proximal fifth as described previously (Fig. 2).1 Care was taken not to divide the separate vascular and nerve pedicles entering each compartment. The smaller ulnar-sided tendon was passed radially and subcutaneously and woven into the extensor pollicis longus tendon while the radial tendon was passed dorsally and woven into the tendons of the extensor digitorum communis. The pronator teres was similarly sutured to the extensor carpi radialis brevis. Tensioning of the transfers was performed with the wrist and metacarpophalangeal joints in neutral and both heads of the FCR stretched.
Lim et al / Independent Function in a Split FCR Transfer
29
Figure 2. FCR is split into an ulnar compartment and a radial compartment before transfer, preserving the proximal fifth of the muscle.
A splint was applied to hold the wrist extended 45° distally to the maximum length, the metacarpophalangeal joints at 10° of flexion, and the interphalangeal joints were extended. Active movements were started 3 weeks after surgery. A rehabilitation program with emphasis on separating extensor pollicis longus and extensor digitorum communis function was instituted at the end of the 3-week period. At 6 months after surgery the patient was able to flex his thumb while extending his fingers and conversely extend his thumb while flexing his fingers (Fig. 3)
Discussion Muscle–tendon units can be split for a variety of reasons. In the lower limb, the tibialis posterior is Figure 1. Sketch showing the anatomy of human FCR based on the findings after Sihler’s staining of the FCR. (T) represents the tendon of FCR that extends to the proximal third of the muscle as an aponeurosis that divides the muscle into a radial compartment (R) and an ulnar compartment (U). The pronator teres (P) is retracted to show the median nerve (M). The median nerve gives out a muscular branch (Br) to the
4™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™ FCR, which enters the muscle in the proximally. As it enters it divides into branches (a), (b), and (c). Branch (a) supplies the radial compartment, whereas the branch (b) supplies the ulnar compartment. Branch (c) supplies fibers in the proximal third of the muscle.
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The Journal of Hand Surgery / Vol. 29A No. 1 January 2004
Figure 3. The function of the thumb and digits at 6 months after the split FCR transfer. (A) Active finger extension and thumb flexion showed the independent contraction of the radial compartment of the FCR to the extensor digitorum communis, with simultaneous relaxation of the ulnar compartment transferred to the extensor pollicis longus, and (B) active thumb extension and finger flexion showing the independent action of the ulnar compartment of the FCR to the extensor pollicis longus with simultaneous relaxation of the radial compartment transferred to the extensor digitorum communis.
often split to balance the foot in both equinovarus deformity and in cerebral palsy.3 In the upper limb the flexor digitorum superficialis tendons to the long and ring fingers have been used to restore extension of the thumb and the digits, respectively, in radial nerve palsy.2 Split abductor pollicis longus tendon and muscle have been used to restore the function of the thumb in cases of ruptured extensor pollicis longus.4 The flexor pollicis longus has been split to provide stability at the interphalangeal joint of the thumb in patients with tetraplegia.5 Most of the actions in the above transfers, however, are synergistic to the action of the muscle being split or act in conjunction with the other actions of the muscle to the digit that received the transfer. Manktelow and Zuker 6 observed that the gracilis has separately innervated motor territories that may contract independently. Parts of the gracilis were used for facial reanimation and Manktelow and Zuker also suggested splitting this muscle into functioning neuromuscular territories. We previously reported independent function in a split transfer of the flexor carpi ulnaris7,8 and have now applied the technique to the FCR muscle. A muscle that is ideal for splitting would have the
following characteristics. The tendon of insertion should have an aponeurosis that extends proximally within the muscle, which allows easy and accurate division in the intercompartmental plane up to the proximal limit, facilitating anatomic and functional separation of the compartments. It is also vital that the nerve and blood supplies to each compartment are independent. Bipennate muscles have this muscle form, and in the forearm, the flexor carpi ulnaris and FCR have been identified as good candidates for split muscle transfers.1,8 Another criterion for split-muscle transfer is that the compartments should also have an adequate physiologic cross-sectional area and fibers length to ensure that they function effectively after transfer.9,10,11 In the case of the FCR, previous work has shown a separate nerve branch from the median nerve to each compartment of the FCR and also an adequate vascular supply to each compartment.1 The muscle architecture has been previously reported to be adequate, with the physiologic crosssectional area and fiber length of the ulnar compartment of the FCR matching those of the extensor pollicis longus, and the physiologic cross-sectional
Lim et al / Independent Function in a Split FCR Transfer
area and fiber length of the radial compartment of the FCR matching those of the extensor digitorum communis.1,8 Splitting the FCR allowed us to perform the transfer in the absence of an adequately functioning palmaris longus. If present, the palmaris longus muscle may also be transferred to restore the function of the abductor pollicis longus for a more complete reconstruction of the thumb. Besides the reconstruction described here, a split FCR transfer may also be used in the group 5 tetraplegic patient.1 Leaving the radial compartment in situ to preserve wrist flexion, the split ulnar compartment of the FCR could be used as a transfer alone to restore thumb opposition. This would provide a quantum improvement in hand function in these severely disabled patients when combined with an extensor carpi radialis longus transfer to the long finger flexors.
References 1. Hua J, Kumar VP, Pereira BP, Lim AYT, Pho RWH, Liu J. Split flexor carpi radialis muscle. Plast Reconstr Surg 1999; 103:930 –934.
31
2. Starr CL. Army experiences with tendon transference. J Bone Joint Surg Am 1922;3:3–21. 3. Kling TF Jr, Kaufer H, Hensinger RN. Split posterior tibialtendon transfers in children with cerebral spastic paralysis and equinovarus deformity. J Bone Joint Surg Am 1985;67: 186 –194. 4. Gelb RI. Tendon transfer for rupture of the extensor pollicis longus. Hand Clin 1995;11:411– 422. 5. Mohammed KD, Rothwell AG, Sinclair SW, Willems SM, Bean AR. Upper-limb surgery for tetraplegia. J Bone Joint Surg Br 1992;74:873– 879. 6. Manktelow RT, Zuker RM. Muscle transplantation by fascicular territory. Plast Reconstr Surg 1984;73:751–757. 7. Lim AYT, Kumar VP, Pereira BP, Hua J. Independent function in a tendon transfer of the split flexor carpi ulnaris. Plast Reconstr Surg 1999;104:1739 –1741. 8. Lim AYT, Kumar VP, Hua J, Pereira BP, Pho RWH. The neuromuscular compartments of the flexor carpi ulnaris. Plast Reconstr Surg 1999;103:1046 –1051. 9. Lieber RL, Jacobson MD, Fazeli BM, Abrams RA, Botte MJ. Architecture of selected muscles of the arm and forearm: anatomy and implications for tendon transfer. J Hand Surg 1992;17A:787–798. 10. Lieber RL, Fride´ n J. Clinical significance of skeletal muscle architecture. Clin Orthop 2001;383:140 –151. 11. Brand PW, Hollister A. Mechanics of individual muscles at individual joints. In: Brand PW, Hollister A, eds. Clinical mechanics of the hand. St Louis: Mosby Year Book, 1992: 254 –352.