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Flexor pollicis longus lacerations
FLEXOR POLLICIS LONGUS LACERATIONS PAUL A. COOK, MD and JAMES F. NAPPI, MD
The flexor pollicis longus muscle tendon unit produces thumb interphalangeal joint flexion. This function is necessary for stable precision tip-to-tip pinch. The mechanism and associated injuries, the location of injury, the interval until reconstruction, and patient requirements are important factors in selecting the method of reconstruction. A systematic approach is presented to aid in selecting a method of reconstruction based on the requirements of the patient. KEY WORDS: flexor pollicis Iongus, lacerations, reconstruction, injury
Contraction of the flexor pollicis longus (FPL) muscle produces thumb interphalangeal (IP) joint flexion. Although this motion is not essential for thumb function, 1it is necessary for normal grasp and precision tip-to-tip pinch. Thus, most investigators advocate surgical reconstruction. Before 1970, most investigators recommended either primary repair or delayed tendon grafting for flexor tendon injuries. 2-6 Dissatisfaction with the functional results after primary repair 2,3 resulted in studies comparing this technique with delayed tendon grafting. 5,6 In one studN primary repair and tendon grafting produced nearly equivalent function results, s In 1967, Kleinert et al 7 published a landmark study that established primary repair as the method of reconstructing the lacerated flexor tendon. We present a systematic approach for selecting a method of reconstructing the damaged FPL.
ANATOMY The FPL is the solitary extrinsic flexor tendon of the thumb. The tendon passes through two annular pulleys and one oblique pulley (Fig 1) and produces independent IP flexion, except in the presence of the Linburg connections (index flexor digitorum profundus connection to the FPL). Similar to the digital flexors, the vascularity of the tendon is based upon a vinculae brevis and longus. However, the vinculum longus is inconsistently present. 1,9-11 Division of the flexor of the thumb into five zones aids in selecting the method of surgical reconstruction (Fig 1). The IP joint and distal (the FPL insertion) comprise zone L The IP joint to the metacarpophalangeal (MP) joint or retinacular system (A1, oblique, and A2 pulleys) constitutes zone II. Deep to the thenar muscles is zone III, which overlaps zone IV or the carpal tunnel. Proximal to the transverse carpal ligament and under the volar forearm fascia is zone V.
METHODS OF SURGICAL RECONSTRUCTION The interval between injury and surgical intervention is important in determining the method of reconstruction. A direct tendon repair performed within 24 hours of injury defines an immediate primary repair. Repairs performed within 21 days of injury are delaved primary repairs. All repairs performed after this period of time are secondary repairs. Despite a delay to reconstruction, direct end-toend coaptation is usually possible and optimal. Severe contamination, soft-tissue loss, and inadequate facilities result in a delayed primary repair (within 21 days of injury) or secondary repair. However, a direct repair may still be possible if the FPL muscle is viable (passive tendon excursion of 1.5 to 2 cm). Tendon loss, tendon sheath scarring, joint contracture, skeletal injury, and a nonviable FPL muscle are factors that necessitate alternate reconstructive solutions. In general a Bruner incision 12,13provides wide exposure of the FPL and surrounding neurovascular structures. This incision is extensile and preferred in zones L II, and III. Alternatively in zones I and II, a midlateral incision avoids the pulp and adequately exposes the flexor sheath. However, this incision provides limited exposure of the contralateral neurovascular bundle. Division of the transverse carpal ligament is necessary for exposure of zone IV Isolated lacerations of the FPL in zone V are exposed through a linear incision between the flexor carpal radialis (FCR) and radial artery. Combined injuries require an extensile carpal tunnel exposure. Direct Repair
Clean, sharp lacerations of the FPL require minimal to no preparation. A 4-0 ethibond suture is the core stitch. We prefer to use the Tajima stitch configuration. 14 A running (or running, locking) epitenon stitch, using 6-0 protene, reduces friction and increases the strength of the repair. 1s-16
From the Hand and Microsurgery Associates, Columbus, OH. Address reprint requests to Paul A. Cook, MD, Hand and Microsurgery Associates,3400 Olentangy River Rd, Columbus, OH 43202. Copyright © 1998 by W.B. Saunders Company 1048-6666/98/t:)802-0005508.00/0
Zone I. The vinculum brevis overlies the volar plate of the IP joint and prevents retraction of the proximal tendon, indirectly maintaining continuity of the FPL. Weak IP joint flexion may be present with lacerations of the FPL in zone I. Lacerations penetrating the volar plate are repaired
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Operative Techniquesin Orthopaedics,Vol 8, No 2 (April), 1998: pp 86-91
guide delivers the tendon into the distal wound, permitting completion of the core stitch. Alternatively, the epitenon stitch can be used to approximate the dorsal surface of the FPL. The Tajima stitch is tied and then the epitenon stitch completed. Repair of the A1 or oblique pulley with 6-0 nylon or prolene prevents tendon bowstringing. Zone IV. Lacerations in zone IV are the most difficult to directly repair. Exposure of the lacerated ends of the FPL requires division of the transverse carpal ligament. After direct repair of the tendon, the transverse carpal ligament is reapproximated. Zone V. The FPL proximal to the transverse carpal ligament is deep to the FCR, ulnar to the radial artery, and dorsal to the median nerve. Similar to zone IV, penetrating trauma in this region usually produces combined injuries. Exposure of the region is through a linear incision ulnar to the palmaris longus. The median nerve is identified and retracted, exposing the lacerated ends of the FPL. Isolated injuries to the FPL are repaired through the interval between the FCR and radial artery. Tendon Advancement
Fig 1. The five zones of the FPL.
using a nonreactive suture such as 6-0 nylon or prolene and then the FPL tendon is repaired. Zones II and III. Lacerations in zones II and III usually result in retraction of the proximal tendon because of the inconsistent presence of the vinculum longus. This repair requires a separate incision at the wrist to expose the retracted tendon (Figs 2A and 2B). The radial artery and FCR tendon are used as surface landmarks. A linear incision placed between the radial artery and FCR is the interval of dissection. Within this interval, the FPL is located dorsal to the FCR in the flexor tenosynovium. The FPL is the most radial digital flexor. Traction on the lacerated FPL delivers the proximal stump into the wrist incision. The Tajima stitch technique is placed in the proximal tendon stump. 14 Through the distal surgical wound, a Hunter rod or pediatric feeding tube is passed retrograde through the fibro-osseous tunnel. This tube serves as a guide for the tendon (Fig 2B). Traction on the
Lacerations within 1 cm of the FPL insertion I or less than a cm of tendon loss are indications for distal advancement of the proximal tendon. However, a patient must be wary because advancement of greater than 5 mm may produce an IP joint flexion contracture. In zone I, the proximal tendon can be advanced and reinserted into bone. Preparation to reinsert the proximal tendon stump into bone requires elevation of a distally based flap of periosteum and tendon, sparing the volar plate. Roughening the volar cortex of the distal phalanx prepares the bone for distal tendon insertion. Using a 2-0 polydioxanone suture, a modified Kessler stitch secures the proximal tendon stump. The two arms of the stitch are passed through two holes around or through the distal phalanx. The sutures exit the fingernail distal to the sterile matrix and then are tied over a bolster. The suture is removed at 6 weeks. Alternatively, a suture anchor may be used to secure the tendon to the distal phalanx. Tendon A d v a n c e m e n t With Lengthening
Surgical management of greater than I cm of tendon loss in zones II and III is distal tendon advancement with proximal Zqengthening (Fig 3)° The FPL is devoid of muscle for 4 cm 1 proximal to the transverse carpal ligament, permitting 2 to 3 cm of Z-lengthening. The segment of FPL tendon traversing zone IV then functions as an in situ vascularized
TABLE 1. Acute FPL Reconstruction Zone
I
II
III
IV
V
Direct
Direct Direct Direct No tendon loss Direct Tendon loss Advance distally Advance distally Advance distally Advancedistally Lessthan 1 cm tendon Advance distally loss Tendon graft if normal Tendon transfer Advance distally and Advance distally and Greater than 1 cm, less Advance distally and muscle and pulleys Creation Linburg proximal Z-lengthening proximal Z-lengthening than 3 cm proximal Z-lengthening Tendon transfer if abnormal muscle
FLEXOR POLLICIS LONGUS LACERATIONS
87
TABLE 2. Chronic FPL Reconstruction Zone NO tendon loss
I Viable FPL muscle Direct Nonviable FPL Tendon transfer muscle
II
Ill
IV
V
Direct Tendon transfer
Direct Tendon transfer
Direct Tendon transfer
Direct Tendon transfer
Tendon loss Less than 1 cm
Viable FPL muscle Advance distally Advance distally Advance distally Advance dista!ly Nonviable FPL Tendon transfer, FPL Tendon transfer, FPL Tendon transfer, FPL Tendon transfer, FPL muscle tenodesis, or IP tenodesis, or IP tenodesis, Or IP tenodesis, or IP fusion for instafusion for instafusion for instafusion for instability bility bility bility Greater than 1 cm, Viable FPL muscle Advance distally and Advance distally and Advance distally and Tendon graft if less than 3 cm proximal Z-lengthproximal Z-lengthproximal Z-lengthnormal muscle ening ening ening and pulleys Tendon transfer if abnormal muscle Greater than 1 cm, Nonviable FPL Tendon transfer, FPL Tendon transfer, FPL Tendon transfer, FPL Tendon transfer, FPL less than 3 cm muscle tenodesis, or IP tenodesis, or IP tenodesis,or IP tenodesis, or IP fusion for instafusion for instafusion for insta, fusion for insta, bility bility bility bility
graft. This technique has the added advantages of the same caliber tendon for direct repair, exact tendon balancing (the amount lengthened equals the amount advanced), and ability to use a Pulvertaft weave at the proximal junction. Deficits in excess of 3 cm or a Linburg connection (common tendon between the FPL and index flexor digitorum profundus [FDP] in zone IV) may require an alternative form of reconstruction. Tendon Grafting
Tendon loss in excess of 3 cm and an inability to perform a direct repair require tendon grafting to restore active IP flexion. Single-stage tendon grafting is indicated when the fibro-osseous tunnel has limited damage. In the presence of a complex w o u n d or damaged fibro-osseous tunnel, two-stage tendon grafting is necessary. Tendon Transfer
Loss of the FPL muscle function caused by direct damage, anterior interosseous nerve injury, or vascular compromise are indications for tendon transfer. The ring finger flexor digitorum superificialis (FDS) transfer reliably restores thumb IP joint flexionY, 18 The ring finger FDS tendon is divided at the proximal finger flexion crease and delivered into a separate incision at the wrist. The distal end of the ring finger FDS tendon is inserted into the distal phalanx similar to a h~ee tendon graft or distal tendon advancement. Tenodesis
Stability of the IP joint of the thumb is necessary for pulp-to-pulp ]?inch and activities requiring power pinch. FPL tenodesis is static and provides IP stability. This technique requires a 1.5 to 3 cm distally based tendon stump. After positioning the IP joint of the thumb in 10 ° to 20 ° of flexion, the proximal end of the distal FPL tendon is sutured to the A1 pulley or volar plate with a nonabsorbable suture material. IP arthrodesis is necessary with instability and an inadequate distal tendon stump. 88
TECHNIQUE
Advance distally Tendon transfer, FPL tenodesis, or IP fusion for insta L bility Tendon transfer
Tendon transfer, FPL ten0desis,or IP fusion for instability
SELECTION
A c u t e F l e x o r Pollicis L o n g u s L a c e r a t i o n s
Immediate direct repair of the lacerated FPL is optimal m all flexor tendon zones with clean wounds (Table 1). When the mechanism of injury or surgical debridement of the w o u n d results in tendon loss, distal advancement of the proximal tendon end permits direct repair. Advancement of the proximal tendon beyond 1 cm produces an IP joint flexion contracture (this often develops after 5 mm of distal advancement). Loss of passive IP extension with the wrist flexed warrants proximal Z-lengthening. The selection of the method of FPL reconstruction with 1 to 3 cm of tendon loss is dependent upon the zone of injury. In zones L II and IIL the proximal tendon end is advanced and directly repaired. This necessitates a separate incision at the wrist to perform Z-lengtherfing of the FPL. In zone IV, the method of reconstruction is dependent upon the integrity of the pulley system and the FPL muscle. We reconstruct tendon loss with a minimally damaged pulley system and a functioning FPL muscle with an acute tendon graft. We prefer to weave the graft proximally at the wrist and insert the distal end into the base of the distal phalanx, avoiding a bridge graft. Damaged A1 and oblique pulleys require two-stage tendon grafting and potentially pulley reconstruction. Excessive tendon loss (>3 era) a n d / o r a nonviable FPL muscle require a tendon transfer to restore active IP flexion. Tendon loss in zone IV can be reconstructed with either tendon transfer (ring finger FDS) or creation of a Linburg connection (tenodesis between the FPL and the index FDP). C h r o n i c F l e x o r Pollicis L o n g u s R e p a i r
Reconstruction of chronic FPL lacerations is dependent upon full passive IP and MCP joint motion, a stable wound, intact pulley system, and a functioning FPL muscle. Direct repair is possible in all zones when passive excursion of the FPL is 1.5 to 2 cm. Muscle damage or loss of passive excursion requires a tendon transfer (active) or FPL COOK AND NAPPI
Fig 2. (A) Bruner incision exposes the FPL and pulley system. (B) A red rubber catheter (pediatric foley) or a Hunter rod passed retrograde through the pulleys serves as a guide for the proximal tendon end. The proximal tendon stump of the FPL is sutured to the catheter and pulled into the distal wound.
FLEXOR POLLICIS LONGUS LACERATIONS
89
Fig 3. Injuries to the FPL that result in less than I cm of tendon are distally advanced. Management of tendon loss greater than 1 cm requires distal tendon advancement and proximal Z-lengthening of the FPL at the wrist, creating an in situ tendon graft.
tenodesis or IP arthrodesis (passive) to reestablish IP joint stability (Table: 2). In zones I, II, and III, tendon loss associated with a viable FPL muscle requires distal tendon advancement with or without proximal Z-lengthening. Inadequate muscle excursion associated with tendon loss are indications for tendon transfer, FPL l:enodesis, or IP arthrodesis. The method of reconstructing zone IV tendon injuries with a viable FPL muscle is the.. same as acute injuries. Similar to acute reconstructive methods, tendon loss in zone V is reconstructed with either tendon transfer (ring finger FDS) or creation of a Linburg connection. Postoperative C a r e
Initially, a splint with 30 ° of wrist and 10° to 20 ° of thumb MP joint flexion (extending past the IP joint) protects the FPL repair. Rubber band traction directed toward the base of the hypothenar eminence is another method that protects the repair, is Traction permits early active thumb extension withian the confines of the splint. Within the first 3 days, passive flexion and active extension or the Duran program 19is ilNtiated. Supervised active flexion (place and hold) is initiated within the first week. In the third to fourth week, gradual splint modification to a wrist neutral position increases tendon gliding. Additionally, full wrist and thumb extension complete mobilization of the repaired FPL tendon. Unrestricted range of motion is permitted 6 weeks after the repair. Strengthening begins 8 to 12 weeks after repair. Loss of IP extension is common after FPL repair. Inability to place the IP joint passively neutrally requires night splinting and extension exercises (active and passive). 90
However, a balance between aggressive attempts at achieving IP extension and protecting the repair site must be considered. Resu Its
Few studies specifically address the techniques and results of FPL reconstruction. ~,2°,21 Historicall}~ most investigators 5,6,22reconstructed both acute and chronic flexor tendon injuries with delayed tendon grafting. In 1973, Urbaniak and Goldner ~ published a study comparing direct repair, delayed repair with or without advancement, and tendon grafting for FPL lacerations. Also, this study defined the technique of reconstruction based on the flexor zone of laceration. Sixty degrees of IP motion and pinch strength equal to the contra]ateral hand defined an excellent result and between 30 ° to 45 ° of IP motion and 50% to 75% pinch strength a good to fair result. Direct repair (7/9) or distal advancement with or without Z-lengthening (16/18) produced 78% and 89% excellent or good results, respectively. Tendon grafting produced 83% (15/18) good or fair results. Concurring with previous literature,C6 Urbaniak and Goldnet t also showed that at least 30 ° of IP flexion was necessary for restoring greater than 75% of pinch strength. Recently, a review of 38 consecutive direct FPL repairs used a standard mobilization program. 21 Immediate direct repairs resulted in a 35 ° average arc of motion and pinch strength of 81% of the contralateral hand. Delayed repairs also provided a stable IP joint but resulted in less motion (averaged 26°). However, no patient achieved normal thumb extension. Repair of lacerations in zones III and IV produced the best results. Most lacerations occurred in zone II (74%) and had associated neurovascular trauma (82%). COOK AND NAPPI
COMPLICATIONS AND MANAGEMENT
ACKNOWLEDGMENT
Crush or avulsing t r a u m a often results in excessive scar formation in and a r o u n d the FPL repair site. In an attempt to p r e v e n t adhesions and joint stiffness (the most c o m m o n problem), active mobilization m a y be initiated the d a y after surgery. This m e t h o d of rehabilitation places additional strain on the repair site, potentially increasing the risk of rupture. However, each t h e r a p y protocol is individualized based u p o n the m a g n i t u d e of scar formation (ie, dense scar formation requires aggressive mobilization). Weeks 4 through 6 are the most c o m m o n period in which ruptures occur. Patients usually report a history of resistive gripping and a p o p p i n g sensation. We p e r f o r m i m m e d i a t e re-repair of the r u p t u r e d tendon. However, observation, two-stage t e n d o n grafting, t e n d o n transfer, tenodesis, or IP arthrodesis are additional reconstructive options. Despite early mobilization protocols, flexor t e n d o n adhesions occur. N o r m a l joint m o t i o n and w o u n d equilibrium are necessary before r e c o m m e n d i n g flexor tenolysis. The interval period of rehabilitation varies b e t w e e n 3 and 12 months. Excessive scarring m a y w a r r a n t two-stage t e n d o n grafting to restore FPL function. A nonviable FPL muscle requires a t e n d o n transfer to restore IP flexion. Weak or inadequate IP flexion, or an IP flexion contracture m a y be secondary to bowstringing of the FPL tendon. This is caused b y an increased m o m e n t arm affecting the IP or MP joint. To achieve normal joint m o t i o n with an inadequate pulley system, a longer t e n d o n excursion is required, which usually exceeds the contractile properties of the FPL muscle. Thus, maximal contraction of the muscle produces w e a k or ineffective pinch. To diagnose bowstringing, digital pressure over the FPL in zone II near the MP joint d u r i n g active flexion improves t e n d o n excursion and joint flexion. Bowstringing typically occurs over joints. Thus, the metaphyseal flares of the phalanges are the optimal location for pulley reconstruction. 23
The authors thank Janet Bailey OT CHT, Nicole Bickhart OT CHT, and L o u a n n Gulick OT C H T for assisting in the preparation of this manuscript.
CONCLUSIONS Flexion of the IP joint of the t h u m b is necessary for precision tip-to-tip pinch and normal grasp. We prefer immediate repair in all acutely lacerated FPL tendons. The inherent advantages of p r i m a r y repair are less m o r b i d i t y (no n e e d for d o n o r tendon), a single-stage reconstruction, and shorter interval necessary for rehabilitation. A l t h o u g h direct repair is optimal, this m e t h o d of reconstruction is not always possible. For instance, a long delay b e t w e e n injury and reconstruction, a complex w o u n d , and t e n d o n loss often require alternative reconstructive solutions to restore IP motion, such as t e n d o n a d v a n c e m e n t with or w i t h o u t lengthening, t e n d o n grafting, t e n d o n transfer, tenodesis, or IP arthrodesis.
FLEXOR POLLICIS LONGUS LACERATIONS
REFERENCES 1. Urbaniak JR, Goldner JL: Laceration of the flexor poUicis longus tendon: Delayed repair by advancement, free graft or direct suture. J Bone Joint Surg Am 55:1123-1148,1973 2. Jemlings ER, Mansberger AR, Smith EP, et al: A new technique in primary tendon repair. Surg Gynecol Obstet 95:597-600,1952 3. Fly~mJE: Problems with trauma to the hand. J Bone Joint Surg Am 35:132-140, 1953 4. Pulvertaft RG: Tendon grafts for flexor tendon injuries in the fingers and thumb, j BoneJoint Surg Br 38:175-194,1956 5. Van't HofA, Kingsbury GH: Flexor-tendon injuries of the fingers and thumb. J BoneJoint Surg Am 40:256-262, 1958 6. Boyes JH, Stark HH: Flexor-tendon grafts in the fingers and thumb. J Bone Joint Surg Am 53:1332-1342,1971 7. Kleinert HE, Kutz JE, Ashbell TS, et al: Primary tendon repair of lacerated flexor tendon in "no-mans land." J Bone Joint Surg Am 49:577, 1967 (abstr) 8. Linburg RM, Comstock BE: Anomalous tendon slips from the flexor pollicis longus to the flexor digitorum profundus. J Hand Surg [Am] 4:79-83, 1979 9. Hergenoeder PT, Gelberman RH, Akeson WH: The vascularity of the flexor pollicis longus tendon. Clin Orthop 162:298-303,1982 10. Azar CA, Culver JE, Fleegler EJ: Blood supply of the flexor pollicis longus tendon. J Hand Surg [Am] 8:471-475,1983 11. Armenta E, Fisher J: Anatomy of flexor pollicis longus vinculum system. J Hand Surg [Am] 9:210-212,1984 12. Bruner JM: Surgical exposure of the flexor pollicis longus tendon. Hand 7:241-245,1975 13. Bruner JM: The zig-zag palmar-digital incision for flexor-tendon surgery. Plast Reconstr Surg 40:571-574,1967 14. Tajima T: Histor~ current status, and aspects of hand surgery in Japan. Clin Orthop 184:41-49,1984 15. Lister GD, Kleinert HE, Kutz JE, et ah Primary flexor tendon repair followed by immediate controlled mobilization. J Hand Surg [Am] 2:441-451, 1977 16. Lin G-T,An K-N, Amadio PC, et ah Biomechanicalstudies of running suture for flexor tendon repair in dogs. J Hand Surg [Am] 13:553-558, 1988 17. Posner MA: Flexor superficialis tendon transfers to the thumb-An alternative to the free tendon graft for treatment of chronic injuries within the digital sheath. J Hand Surg [Am] 8:876-881,1983 18. Schneider LH, Wiltshire D: Restoration of flexor pollicis longus function by flexor digitorum superficialis transfer. J Hand Surg [Am] 8:98-101, 1983 19. Duran RJ, Houser RG, Stover MG: Management of flexor tendon laceations in zone II using controlled passive motion postoperatively, in Hunter JM, Schneider LH, Macklin EJ, et al (eds): Rehabilitation of the Hand. St. Louis, MO, Mosb~ 1978,chap 18 20. Murphy FG: Repair of lacerations of the flexor pollicis longus tendon. J Bone Joint Surg Am 19:1121-1123,1937 21. Nunley JA, Levin LS, Devito D, et ah Direct end-to-end repair of flexor pollicis longus tendon lacerations. J Hand Surg [Am] 17:118-121,1992 22. KellyAP: Primary tendon repairs: A study of 789 consecutive tendon severences.J BoneJoint Surg Am 41:581-598,1959 23. Hume EL, Hutchinson DT, Jaeger SA, et al: Biomechanicsof pulley reconstruction. J Hand Surg [Am] 16:722-730,1991
91
The flexor pollicis longus muscle tendon unit produces thumb interphalangeal joint flexion. This function is necessary for stable precision tip-to-tip pinch. The mechanism and associated injuries, the location of injury, the interval until reconstruction, and patient requirements are important factors in selecting the method of reconstruction. A systematic approach is presented to aid in selecting a method of reconstruction based on the requirements of the patient. KEY WORDS: flexor pollicis Iongus, lacerations, reconstruction, injury
Contraction of the flexor pollicis longus (FPL) muscle produces thumb interphalangeal (IP) joint flexion. Although this motion is not essential for thumb function, 1it is necessary for normal grasp and precision tip-to-tip pinch. Thus, most investigators advocate surgical reconstruction. Before 1970, most investigators recommended either primary repair or delayed tendon grafting for flexor tendon injuries. 2-6 Dissatisfaction with the functional results after primary repair 2,3 resulted in studies comparing this technique with delayed tendon grafting. 5,6 In one studN primary repair and tendon grafting produced nearly equivalent function results, s In 1967, Kleinert et al 7 published a landmark study that established primary repair as the method of reconstructing the lacerated flexor tendon. We present a systematic approach for selecting a method of reconstructing the damaged FPL.
ANATOMY The FPL is the solitary extrinsic flexor tendon of the thumb. The tendon passes through two annular pulleys and one oblique pulley (Fig 1) and produces independent IP flexion, except in the presence of the Linburg connections (index flexor digitorum profundus connection to the FPL). Similar to the digital flexors, the vascularity of the tendon is based upon a vinculae brevis and longus. However, the vinculum longus is inconsistently present. 1,9-11 Division of the flexor of the thumb into five zones aids in selecting the method of surgical reconstruction (Fig 1). The IP joint and distal (the FPL insertion) comprise zone L The IP joint to the metacarpophalangeal (MP) joint or retinacular system (A1, oblique, and A2 pulleys) constitutes zone II. Deep to the thenar muscles is zone III, which overlaps zone IV or the carpal tunnel. Proximal to the transverse carpal ligament and under the volar forearm fascia is zone V.
METHODS OF SURGICAL RECONSTRUCTION The interval between injury and surgical intervention is important in determining the method of reconstruction. A direct tendon repair performed within 24 hours of injury defines an immediate primary repair. Repairs performed within 21 days of injury are delaved primary repairs. All repairs performed after this period of time are secondary repairs. Despite a delay to reconstruction, direct end-toend coaptation is usually possible and optimal. Severe contamination, soft-tissue loss, and inadequate facilities result in a delayed primary repair (within 21 days of injury) or secondary repair. However, a direct repair may still be possible if the FPL muscle is viable (passive tendon excursion of 1.5 to 2 cm). Tendon loss, tendon sheath scarring, joint contracture, skeletal injury, and a nonviable FPL muscle are factors that necessitate alternate reconstructive solutions. In general a Bruner incision 12,13provides wide exposure of the FPL and surrounding neurovascular structures. This incision is extensile and preferred in zones L II, and III. Alternatively in zones I and II, a midlateral incision avoids the pulp and adequately exposes the flexor sheath. However, this incision provides limited exposure of the contralateral neurovascular bundle. Division of the transverse carpal ligament is necessary for exposure of zone IV Isolated lacerations of the FPL in zone V are exposed through a linear incision between the flexor carpal radialis (FCR) and radial artery. Combined injuries require an extensile carpal tunnel exposure. Direct Repair
Clean, sharp lacerations of the FPL require minimal to no preparation. A 4-0 ethibond suture is the core stitch. We prefer to use the Tajima stitch configuration. 14 A running (or running, locking) epitenon stitch, using 6-0 protene, reduces friction and increases the strength of the repair. 1s-16
From the Hand and Microsurgery Associates, Columbus, OH. Address reprint requests to Paul A. Cook, MD, Hand and Microsurgery Associates,3400 Olentangy River Rd, Columbus, OH 43202. Copyright © 1998 by W.B. Saunders Company 1048-6666/98/t:)802-0005508.00/0
Zone I. The vinculum brevis overlies the volar plate of the IP joint and prevents retraction of the proximal tendon, indirectly maintaining continuity of the FPL. Weak IP joint flexion may be present with lacerations of the FPL in zone I. Lacerations penetrating the volar plate are repaired
86
Operative Techniquesin Orthopaedics,Vol 8, No 2 (April), 1998: pp 86-91
guide delivers the tendon into the distal wound, permitting completion of the core stitch. Alternatively, the epitenon stitch can be used to approximate the dorsal surface of the FPL. The Tajima stitch is tied and then the epitenon stitch completed. Repair of the A1 or oblique pulley with 6-0 nylon or prolene prevents tendon bowstringing. Zone IV. Lacerations in zone IV are the most difficult to directly repair. Exposure of the lacerated ends of the FPL requires division of the transverse carpal ligament. After direct repair of the tendon, the transverse carpal ligament is reapproximated. Zone V. The FPL proximal to the transverse carpal ligament is deep to the FCR, ulnar to the radial artery, and dorsal to the median nerve. Similar to zone IV, penetrating trauma in this region usually produces combined injuries. Exposure of the region is through a linear incision ulnar to the palmaris longus. The median nerve is identified and retracted, exposing the lacerated ends of the FPL. Isolated injuries to the FPL are repaired through the interval between the FCR and radial artery. Tendon Advancement
Fig 1. The five zones of the FPL.
using a nonreactive suture such as 6-0 nylon or prolene and then the FPL tendon is repaired. Zones II and III. Lacerations in zones II and III usually result in retraction of the proximal tendon because of the inconsistent presence of the vinculum longus. This repair requires a separate incision at the wrist to expose the retracted tendon (Figs 2A and 2B). The radial artery and FCR tendon are used as surface landmarks. A linear incision placed between the radial artery and FCR is the interval of dissection. Within this interval, the FPL is located dorsal to the FCR in the flexor tenosynovium. The FPL is the most radial digital flexor. Traction on the lacerated FPL delivers the proximal stump into the wrist incision. The Tajima stitch technique is placed in the proximal tendon stump. 14 Through the distal surgical wound, a Hunter rod or pediatric feeding tube is passed retrograde through the fibro-osseous tunnel. This tube serves as a guide for the tendon (Fig 2B). Traction on the
Lacerations within 1 cm of the FPL insertion I or less than a cm of tendon loss are indications for distal advancement of the proximal tendon. However, a patient must be wary because advancement of greater than 5 mm may produce an IP joint flexion contracture. In zone I, the proximal tendon can be advanced and reinserted into bone. Preparation to reinsert the proximal tendon stump into bone requires elevation of a distally based flap of periosteum and tendon, sparing the volar plate. Roughening the volar cortex of the distal phalanx prepares the bone for distal tendon insertion. Using a 2-0 polydioxanone suture, a modified Kessler stitch secures the proximal tendon stump. The two arms of the stitch are passed through two holes around or through the distal phalanx. The sutures exit the fingernail distal to the sterile matrix and then are tied over a bolster. The suture is removed at 6 weeks. Alternatively, a suture anchor may be used to secure the tendon to the distal phalanx. Tendon A d v a n c e m e n t With Lengthening
Surgical management of greater than I cm of tendon loss in zones II and III is distal tendon advancement with proximal Zqengthening (Fig 3)° The FPL is devoid of muscle for 4 cm 1 proximal to the transverse carpal ligament, permitting 2 to 3 cm of Z-lengthening. The segment of FPL tendon traversing zone IV then functions as an in situ vascularized
TABLE 1. Acute FPL Reconstruction Zone
I
II
III
IV
V
Direct
Direct Direct Direct No tendon loss Direct Tendon loss Advance distally Advance distally Advance distally Advancedistally Lessthan 1 cm tendon Advance distally loss Tendon graft if normal Tendon transfer Advance distally and Advance distally and Greater than 1 cm, less Advance distally and muscle and pulleys Creation Linburg proximal Z-lengthening proximal Z-lengthening than 3 cm proximal Z-lengthening Tendon transfer if abnormal muscle
FLEXOR POLLICIS LONGUS LACERATIONS
87
TABLE 2. Chronic FPL Reconstruction Zone NO tendon loss
I Viable FPL muscle Direct Nonviable FPL Tendon transfer muscle
II
Ill
IV
V
Direct Tendon transfer
Direct Tendon transfer
Direct Tendon transfer
Direct Tendon transfer
Tendon loss Less than 1 cm
Viable FPL muscle Advance distally Advance distally Advance distally Advance dista!ly Nonviable FPL Tendon transfer, FPL Tendon transfer, FPL Tendon transfer, FPL Tendon transfer, FPL muscle tenodesis, or IP tenodesis, or IP tenodesis, Or IP tenodesis, or IP fusion for instafusion for instafusion for instafusion for instability bility bility bility Greater than 1 cm, Viable FPL muscle Advance distally and Advance distally and Advance distally and Tendon graft if less than 3 cm proximal Z-lengthproximal Z-lengthproximal Z-lengthnormal muscle ening ening ening and pulleys Tendon transfer if abnormal muscle Greater than 1 cm, Nonviable FPL Tendon transfer, FPL Tendon transfer, FPL Tendon transfer, FPL Tendon transfer, FPL less than 3 cm muscle tenodesis, or IP tenodesis, or IP tenodesis,or IP tenodesis, or IP fusion for instafusion for instafusion for insta, fusion for insta, bility bility bility bility
graft. This technique has the added advantages of the same caliber tendon for direct repair, exact tendon balancing (the amount lengthened equals the amount advanced), and ability to use a Pulvertaft weave at the proximal junction. Deficits in excess of 3 cm or a Linburg connection (common tendon between the FPL and index flexor digitorum profundus [FDP] in zone IV) may require an alternative form of reconstruction. Tendon Grafting
Tendon loss in excess of 3 cm and an inability to perform a direct repair require tendon grafting to restore active IP flexion. Single-stage tendon grafting is indicated when the fibro-osseous tunnel has limited damage. In the presence of a complex w o u n d or damaged fibro-osseous tunnel, two-stage tendon grafting is necessary. Tendon Transfer
Loss of the FPL muscle function caused by direct damage, anterior interosseous nerve injury, or vascular compromise are indications for tendon transfer. The ring finger flexor digitorum superificialis (FDS) transfer reliably restores thumb IP joint flexionY, 18 The ring finger FDS tendon is divided at the proximal finger flexion crease and delivered into a separate incision at the wrist. The distal end of the ring finger FDS tendon is inserted into the distal phalanx similar to a h~ee tendon graft or distal tendon advancement. Tenodesis
Stability of the IP joint of the thumb is necessary for pulp-to-pulp ]?inch and activities requiring power pinch. FPL tenodesis is static and provides IP stability. This technique requires a 1.5 to 3 cm distally based tendon stump. After positioning the IP joint of the thumb in 10 ° to 20 ° of flexion, the proximal end of the distal FPL tendon is sutured to the A1 pulley or volar plate with a nonabsorbable suture material. IP arthrodesis is necessary with instability and an inadequate distal tendon stump. 88
TECHNIQUE
Advance distally Tendon transfer, FPL tenodesis, or IP fusion for insta L bility Tendon transfer
Tendon transfer, FPL ten0desis,or IP fusion for instability
SELECTION
A c u t e F l e x o r Pollicis L o n g u s L a c e r a t i o n s
Immediate direct repair of the lacerated FPL is optimal m all flexor tendon zones with clean wounds (Table 1). When the mechanism of injury or surgical debridement of the w o u n d results in tendon loss, distal advancement of the proximal tendon end permits direct repair. Advancement of the proximal tendon beyond 1 cm produces an IP joint flexion contracture (this often develops after 5 mm of distal advancement). Loss of passive IP extension with the wrist flexed warrants proximal Z-lengthening. The selection of the method of FPL reconstruction with 1 to 3 cm of tendon loss is dependent upon the zone of injury. In zones L II and IIL the proximal tendon end is advanced and directly repaired. This necessitates a separate incision at the wrist to perform Z-lengtherfing of the FPL. In zone IV, the method of reconstruction is dependent upon the integrity of the pulley system and the FPL muscle. We reconstruct tendon loss with a minimally damaged pulley system and a functioning FPL muscle with an acute tendon graft. We prefer to weave the graft proximally at the wrist and insert the distal end into the base of the distal phalanx, avoiding a bridge graft. Damaged A1 and oblique pulleys require two-stage tendon grafting and potentially pulley reconstruction. Excessive tendon loss (>3 era) a n d / o r a nonviable FPL muscle require a tendon transfer to restore active IP flexion. Tendon loss in zone IV can be reconstructed with either tendon transfer (ring finger FDS) or creation of a Linburg connection (tenodesis between the FPL and the index FDP). C h r o n i c F l e x o r Pollicis L o n g u s R e p a i r
Reconstruction of chronic FPL lacerations is dependent upon full passive IP and MCP joint motion, a stable wound, intact pulley system, and a functioning FPL muscle. Direct repair is possible in all zones when passive excursion of the FPL is 1.5 to 2 cm. Muscle damage or loss of passive excursion requires a tendon transfer (active) or FPL COOK AND NAPPI
Fig 2. (A) Bruner incision exposes the FPL and pulley system. (B) A red rubber catheter (pediatric foley) or a Hunter rod passed retrograde through the pulleys serves as a guide for the proximal tendon end. The proximal tendon stump of the FPL is sutured to the catheter and pulled into the distal wound.
FLEXOR POLLICIS LONGUS LACERATIONS
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Fig 3. Injuries to the FPL that result in less than I cm of tendon are distally advanced. Management of tendon loss greater than 1 cm requires distal tendon advancement and proximal Z-lengthening of the FPL at the wrist, creating an in situ tendon graft.
tenodesis or IP arthrodesis (passive) to reestablish IP joint stability (Table: 2). In zones I, II, and III, tendon loss associated with a viable FPL muscle requires distal tendon advancement with or without proximal Z-lengthening. Inadequate muscle excursion associated with tendon loss are indications for tendon transfer, FPL l:enodesis, or IP arthrodesis. The method of reconstructing zone IV tendon injuries with a viable FPL muscle is the.. same as acute injuries. Similar to acute reconstructive methods, tendon loss in zone V is reconstructed with either tendon transfer (ring finger FDS) or creation of a Linburg connection. Postoperative C a r e
Initially, a splint with 30 ° of wrist and 10° to 20 ° of thumb MP joint flexion (extending past the IP joint) protects the FPL repair. Rubber band traction directed toward the base of the hypothenar eminence is another method that protects the repair, is Traction permits early active thumb extension withian the confines of the splint. Within the first 3 days, passive flexion and active extension or the Duran program 19is ilNtiated. Supervised active flexion (place and hold) is initiated within the first week. In the third to fourth week, gradual splint modification to a wrist neutral position increases tendon gliding. Additionally, full wrist and thumb extension complete mobilization of the repaired FPL tendon. Unrestricted range of motion is permitted 6 weeks after the repair. Strengthening begins 8 to 12 weeks after repair. Loss of IP extension is common after FPL repair. Inability to place the IP joint passively neutrally requires night splinting and extension exercises (active and passive). 90
However, a balance between aggressive attempts at achieving IP extension and protecting the repair site must be considered. Resu Its
Few studies specifically address the techniques and results of FPL reconstruction. ~,2°,21 Historicall}~ most investigators 5,6,22reconstructed both acute and chronic flexor tendon injuries with delayed tendon grafting. In 1973, Urbaniak and Goldner ~ published a study comparing direct repair, delayed repair with or without advancement, and tendon grafting for FPL lacerations. Also, this study defined the technique of reconstruction based on the flexor zone of laceration. Sixty degrees of IP motion and pinch strength equal to the contra]ateral hand defined an excellent result and between 30 ° to 45 ° of IP motion and 50% to 75% pinch strength a good to fair result. Direct repair (7/9) or distal advancement with or without Z-lengthening (16/18) produced 78% and 89% excellent or good results, respectively. Tendon grafting produced 83% (15/18) good or fair results. Concurring with previous literature,C6 Urbaniak and Goldnet t also showed that at least 30 ° of IP flexion was necessary for restoring greater than 75% of pinch strength. Recently, a review of 38 consecutive direct FPL repairs used a standard mobilization program. 21 Immediate direct repairs resulted in a 35 ° average arc of motion and pinch strength of 81% of the contralateral hand. Delayed repairs also provided a stable IP joint but resulted in less motion (averaged 26°). However, no patient achieved normal thumb extension. Repair of lacerations in zones III and IV produced the best results. Most lacerations occurred in zone II (74%) and had associated neurovascular trauma (82%). COOK AND NAPPI
COMPLICATIONS AND MANAGEMENT
ACKNOWLEDGMENT
Crush or avulsing t r a u m a often results in excessive scar formation in and a r o u n d the FPL repair site. In an attempt to p r e v e n t adhesions and joint stiffness (the most c o m m o n problem), active mobilization m a y be initiated the d a y after surgery. This m e t h o d of rehabilitation places additional strain on the repair site, potentially increasing the risk of rupture. However, each t h e r a p y protocol is individualized based u p o n the m a g n i t u d e of scar formation (ie, dense scar formation requires aggressive mobilization). Weeks 4 through 6 are the most c o m m o n period in which ruptures occur. Patients usually report a history of resistive gripping and a p o p p i n g sensation. We p e r f o r m i m m e d i a t e re-repair of the r u p t u r e d tendon. However, observation, two-stage t e n d o n grafting, t e n d o n transfer, tenodesis, or IP arthrodesis are additional reconstructive options. Despite early mobilization protocols, flexor t e n d o n adhesions occur. N o r m a l joint m o t i o n and w o u n d equilibrium are necessary before r e c o m m e n d i n g flexor tenolysis. The interval period of rehabilitation varies b e t w e e n 3 and 12 months. Excessive scarring m a y w a r r a n t two-stage t e n d o n grafting to restore FPL function. A nonviable FPL muscle requires a t e n d o n transfer to restore IP flexion. Weak or inadequate IP flexion, or an IP flexion contracture m a y be secondary to bowstringing of the FPL tendon. This is caused b y an increased m o m e n t arm affecting the IP or MP joint. To achieve normal joint m o t i o n with an inadequate pulley system, a longer t e n d o n excursion is required, which usually exceeds the contractile properties of the FPL muscle. Thus, maximal contraction of the muscle produces w e a k or ineffective pinch. To diagnose bowstringing, digital pressure over the FPL in zone II near the MP joint d u r i n g active flexion improves t e n d o n excursion and joint flexion. Bowstringing typically occurs over joints. Thus, the metaphyseal flares of the phalanges are the optimal location for pulley reconstruction. 23
The authors thank Janet Bailey OT CHT, Nicole Bickhart OT CHT, and L o u a n n Gulick OT C H T for assisting in the preparation of this manuscript.
CONCLUSIONS Flexion of the IP joint of the t h u m b is necessary for precision tip-to-tip pinch and normal grasp. We prefer immediate repair in all acutely lacerated FPL tendons. The inherent advantages of p r i m a r y repair are less m o r b i d i t y (no n e e d for d o n o r tendon), a single-stage reconstruction, and shorter interval necessary for rehabilitation. A l t h o u g h direct repair is optimal, this m e t h o d of reconstruction is not always possible. For instance, a long delay b e t w e e n injury and reconstruction, a complex w o u n d , and t e n d o n loss often require alternative reconstructive solutions to restore IP motion, such as t e n d o n a d v a n c e m e n t with or w i t h o u t lengthening, t e n d o n grafting, t e n d o n transfer, tenodesis, or IP arthrodesis.
FLEXOR POLLICIS LONGUS LACERATIONS
REFERENCES 1. Urbaniak JR, Goldner JL: Laceration of the flexor poUicis longus tendon: Delayed repair by advancement, free graft or direct suture. J Bone Joint Surg Am 55:1123-1148,1973 2. Jemlings ER, Mansberger AR, Smith EP, et al: A new technique in primary tendon repair. Surg Gynecol Obstet 95:597-600,1952 3. Fly~mJE: Problems with trauma to the hand. J Bone Joint Surg Am 35:132-140, 1953 4. Pulvertaft RG: Tendon grafts for flexor tendon injuries in the fingers and thumb, j BoneJoint Surg Br 38:175-194,1956 5. Van't HofA, Kingsbury GH: Flexor-tendon injuries of the fingers and thumb. J BoneJoint Surg Am 40:256-262, 1958 6. Boyes JH, Stark HH: Flexor-tendon grafts in the fingers and thumb. J Bone Joint Surg Am 53:1332-1342,1971 7. Kleinert HE, Kutz JE, Ashbell TS, et al: Primary tendon repair of lacerated flexor tendon in "no-mans land." J Bone Joint Surg Am 49:577, 1967 (abstr) 8. Linburg RM, Comstock BE: Anomalous tendon slips from the flexor pollicis longus to the flexor digitorum profundus. J Hand Surg [Am] 4:79-83, 1979 9. Hergenoeder PT, Gelberman RH, Akeson WH: The vascularity of the flexor pollicis longus tendon. Clin Orthop 162:298-303,1982 10. Azar CA, Culver JE, Fleegler EJ: Blood supply of the flexor pollicis longus tendon. J Hand Surg [Am] 8:471-475,1983 11. Armenta E, Fisher J: Anatomy of flexor pollicis longus vinculum system. J Hand Surg [Am] 9:210-212,1984 12. Bruner JM: Surgical exposure of the flexor pollicis longus tendon. Hand 7:241-245,1975 13. Bruner JM: The zig-zag palmar-digital incision for flexor-tendon surgery. Plast Reconstr Surg 40:571-574,1967 14. Tajima T: Histor~ current status, and aspects of hand surgery in Japan. Clin Orthop 184:41-49,1984 15. Lister GD, Kleinert HE, Kutz JE, et ah Primary flexor tendon repair followed by immediate controlled mobilization. J Hand Surg [Am] 2:441-451, 1977 16. Lin G-T,An K-N, Amadio PC, et ah Biomechanicalstudies of running suture for flexor tendon repair in dogs. J Hand Surg [Am] 13:553-558, 1988 17. Posner MA: Flexor superficialis tendon transfers to the thumb-An alternative to the free tendon graft for treatment of chronic injuries within the digital sheath. J Hand Surg [Am] 8:876-881,1983 18. Schneider LH, Wiltshire D: Restoration of flexor pollicis longus function by flexor digitorum superficialis transfer. J Hand Surg [Am] 8:98-101, 1983 19. Duran RJ, Houser RG, Stover MG: Management of flexor tendon laceations in zone II using controlled passive motion postoperatively, in Hunter JM, Schneider LH, Macklin EJ, et al (eds): Rehabilitation of the Hand. St. Louis, MO, Mosb~ 1978,chap 18 20. Murphy FG: Repair of lacerations of the flexor pollicis longus tendon. J Bone Joint Surg Am 19:1121-1123,1937 21. Nunley JA, Levin LS, Devito D, et ah Direct end-to-end repair of flexor pollicis longus tendon lacerations. J Hand Surg [Am] 17:118-121,1992 22. KellyAP: Primary tendon repairs: A study of 789 consecutive tendon severences.J BoneJoint Surg Am 41:581-598,1959 23. Hume EL, Hutchinson DT, Jaeger SA, et al: Biomechanicsof pulley reconstruction. J Hand Surg [Am] 16:722-730,1991
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