PARTIAL FLEXOR DIGITORUM PROFUNDUS LACERATIONS MARSHALL L. BALK, MD and DEAN G. SOTEREANOS, MD
The management of partially lacerated flexor tendons remains controversial. Some have advocated repair of a partially severed tendon to restore gliding function, whereas others have recommended foregoing tenorrhaphy because of the negative impact of repair on the tensile strength of the tendon. Studies in several laboratories have suggested that tendons with up to 60% cross-sectional area involvement may be strong enough to withstand an early active mobilization regimen without rupturel In addition, tenorrhaphy does not significantly improve gliding function in tendons with up to 70% laceration. For these reasons, we recommend tenorrhaphy only for those tendons with greater than 60% laceration of cross-sectional area or those that trigger. Meticulous surgical technique and early protected mobilization provide the best chance for an optimal result. KEY WORDS: tenorrhaphy, partial laceration, flexor tendon, gliding function
Much controversy has historically surrounded the management of partially lacerated digital flexor tendons. When compared with the study of complete lacerations, there is a relative paucity of experimental data regarding the appropriate management of partially lacerated tendons. As such, clinical decisions have often been extrapolated either from studies on completely lacerated tendons or from anecdotal evidence. Some have advocated repair of a partially severed tendon to restore gliding function, 1 whereas others have recommended foregoing tenorrhaphy because of the negative impact of repair on the tensile strength of the tendon. 2-4 Complications such as triggering, rupture, and entrapment are considered by some investigators to be reduced after tenorrhaphy 1,5-8 whereas others suggest that tenorrhaphy, in particular, enhances the risk of rupture. 3,9 With this disparity in opinions, the management of partially lacerated flexor tendons remains controversial. We have shown that tenorrhaphy does not significantly improve gliding function in tendons with up to 70% laceration 1° and that tendons with up to 60% involvement may be able to tolerate an early active mobilization program. 11For these reasons, we recommend tenorrhaphy only for those tendons with greater than 60% laceration of cross-sectional area or those that trigger.
BASIC SCIENCE The results of tenorrhaphy for completely transected tendons have been studied extensively. The influences of sheath repair, suturing methods, tendon grafting, and various mobilization regimens have been examined in detail for this type of injury.12-20In addition, mechanisms of From the Department of Orthopaedic Surgery, University of Pittsburgh, Pittsburgh, PA. Address reprint requests to Dean G. Sotereanos, MD, University Orthopaedics, 3471 Fifth Ave, Suite 1010, Kaufmann Bldg, Pittsburgh, PA 15213. Copyright © 1998 by W.B. Saunders Company 1048-6666/98/0802-0002508.00/0
Operative Techniques in Orthopaedics, Vol 8, No 2 (April), 1998: pp 67-72
tendon nutrition have been elucidated, which have enhanced our understanding of the tendon healing process.2T M UnfortunatelN there is a relative lack of experimental data detailing the physiology behind tenorrhaphy of partially lacerated tendons. Reynolds et aP studied the tensile strength of partially severed tendons in a chicken model and showed that the mean tensile strength of nonsutured tendons was significantly higher than those that had been repaired. They recommended that tenorrhaphy not be undertaken in partially lacerated tendons. 3 Kleinert1postulated that tenorrhaphy of partial lacerations is undertaken to improve gliding function rather than tensile strength, that unrepaired tendons are vulnerable to bulbous scar formation, thereby allowing triggering or incomplete excursion of the tendon through the fibro-osseous pulleys. Bishop evaluated the effects of immobilization, early protected mobilization, tenorrhaphy, and no repair of partial flexor tendon lacerations of 60% of cross-sectional area in a canine model. They showed significant adverse effects on breaking strength, stiffness, and energy absorption with tenorrhaphy. In addition, early passive range of motion improved excursion and stiffness significantly. They concluded that partially lacerated tendons of 60% cross-sectional area are optimally treated without tenorrhaphy and with early mobilization. 2 Early experiments in our laboratory studied the effect of varying degrees of partial laceration on the structural properties of the canme flexor digitorum profundus tendon. Lacerations up to 90% of the tendon cross-sectional area were created surgically in the sagittal plane. Structural properties of the tendon were noted to be adversely affected as laceration size increased (Fig 1). 22 Correlating this information to the in vivo forces in the intrasynovial tendon 25 is difficult though. Bright and Urbaniak 26 quantitated the tension in human flexor tendons during active and passive motion. During flexion and extension, flexor tendons are constantly subjected to variable tensions ranging from 500 to 2,500 g.26 Cooney et a127 reported that 67
600
....
500 1
i
Index/Middle (r2=0"60)
BRIEF DESCRIPTION OF OTHER TECHNIQUES
30O
~200
-,
100 ~Ring/Little
N
""
, "b,," 0
20 40 60 80 100 Degree of Laceration (%)
Fig 1. Diagram illustrates strengths of tendon versus degree of laceration. (Reprinted with permission, 11) human flexor tendon force during active flexion with mild resistance (2 to 3 N) was 9 to 10 N. Weightman and Amis 2s reported that loads up to 250 N could be applied to the tendons during active use of the digits. Based on these estimates of in vivo forces, even tendons with up to 60% cross-sectional area involvement may be strong enough to withstand an ,early active mobilization regimen without rupture. Additional studies evaluated the impact of tenorrhaphy on the gliding: function and tensile properties of canine flexor tendons with tendons involving either 30% or 70% of their cross-sectional area. Tendons were either repaired with a modified Kessler technique or left unrepaired. Assessment of tendon excursion and joint rotation after 6 weeks of postoperative controlled passive mobilization failed to show any statistically significant benefit from tenorrhaphy on gliding function. In fact, tenorrhaphy on tendons with :30% lacerations showed a significant negative effect with regard to gliding function. Moreover, no significant differences between the structural properties or integrity of the repaired and nonrepaired tendons could be shown. This study suggests that digital function of partially lacerated tendons of up to 70% of the cross-sectional area may be preserved without primary repair. 1°
INDICATIONS A survey was taken of 1,000 members of the American Society for Surgery of the Hand to determine the methods by which clinicians treat partial lacerations of flexor tendons. Results from 591 respondents showed that 30% repair all partial lacerations whereas 45% repair only those lacerations greater than 50%. Nearly two thirds of respondents approach transverse and oblique lacerations in the same manner. Most respondents use a modified Kessler suture technique and begin protected mobilization within the first 48 h o u r s . 29 Our practice is to explore the wound and assess for evidence of trJiggering. The cross-sectional involvement is assessed under loupe magnification. Only those tendons that trigger or have greater than 60% involvement undergo formal tenorrhaphy. Bevelled lacerations with less than 68
60% involvement undergo debridement given the propensity for triggering or tendon entrapment with increasingly oblique lacerations.
Schlenker et al 8 recommend tenorrhaphy for tendon lacerations greater than 25% of the cross-sectional area. For tendons lacerated less than 50%, a running suture of number 6-0 braided synthetic is placed in the epitenon. This suture should be placed only around the lacerated portion of the circumference of the tendon to provide a smooth gliding surface (Fig 2A). For a 50% or greater laceration of the tendor~, a modified Kessler-Mason-Allen suture of number 4-0 or 5-0 is used. The repair is completed by placing a running suture around the periphery of the cut tendon (Fig 2B).8 Weeks 3° described his method of managing partial flexor tendon lacerations based on the level of injury. If the tendon laceration is proximal to the A1 pulley, the tendon is debrided (if bevelled) followed bv dorsal splinting. If the laceration is within the digital sheath, Weeks recommends repair of the sheath followed by clinical examination. If triggering occurs, primary repair is indicated. Otherwise, the partially cut tendon is not sutured, and early motion is allowed to the point of discomfort. 3°
TECHNIQUE Incision Partial tendon lacerations commorfly occur from penetrating trauma to the digit, If the wound is oblique, we incorporate the laceration into Bruner's palmar zigzag incision. Other wounds can be extended via a midlateral approach to the digit. 3~ Approach If intact, the flexor tendon sheath is opened with an L-shaped incision in cruciate windows. If irreparable, part of the sheath surrounding the injury site must be excised to prevent catching or triggering. Care is taken to preserve all annular pulleys. Tendon Preparation The partially lacerated tendon is examined under loupe magnification. Knowledge of the ulnar and radial bundle patterns in each digit is helpful for accurate estimation of cross-sectional area of the laceration (Fig 3). In the index and small fingers, the ulnar bundle has a mean crosssectional area greater than 50% of total tendon area. In the middle finger, the mean areas of both bundles are close to 50% of total tendon area, but the radial bundle is reduced at the level of the proximal interphalangeal joint and distally. In the ring finger, both bundles are close to 50% of total tendon area at all levels. 32 BALK AND SOTEREANOS
Fig 3. A histological section showing the ulnar and radial bundles of the flexor digitorum profundus in zone II,
Minimal debridement of the tendon is required, but bevelled edges are squared with a No. 15 blade to allow smooth gliding and ease of repair. Debridement is performed through a cruciate window. Lacerations in the coronal and sagittal planes are treated in the same fashion, although, in our experience, coronal lacerations are quite rare. Final Repair
Tendons with less than 60% cross-sectional involvement are debrided to ensure smooth gliding function. The finger is then placed through a range of motion. If there is any evidence of triggering or entrapment, the tendon undergoes formal repair. Tendons with greater than 60% laceration are likewise debrided to enable apposition of tendon edges. Under loupe magnification, the severed tendon is repaired with a 4-0 braided synthetic core stitch using a modified Kessler technique (Fig 4). When possible, the edges of the tendon are carefully repaired with a running, locking 7-0 epitendinous suture. The sheath is not routinely repaired. Pitfalls
Fig 2. (A) For a less than 50% laceration of the tendon, a running suture of No. 6-0 braided synthetic suture is placed in the epitenon around the periphery of the lacerated portion of the tendon. (B) For a 50% or greater laceration of the tendon, a modified Kessler-Mason-Allen suture of No. 4-0 is placed followed by a running peripheral suture. PARTIAL FLEXOR DIGITORUM PROFUNDUSLACERATIONS
Only the cut ends of the tendon should be handled because injury to the epitenon can induce adhesion formation. Repair of the tendon must ensure approximation of tendon edges, as "bunching" of the tendon at the suture line may inhibit smooth gliding function. The 7-0 epitendinous suture is helpful in ensuring this. For smaller tendons, a 5-0 braided nylon suture is sometimes used as a core stitch. The core stitch should be placed into the volar 50% of the tendon to minimize injury to the blood supply from the vincula entering the dorsal surface. The digit must be placed through a complete range of motion intraoperatively. If there is any evidence of triggering or incomplete excursion of the tendon, either the tendon or the sheath requires further debridement. If triggering persists after debridement, formal tenorrhaphy is recommended. 69
Fig 4. The modified Kessler stitch consists of a single 4,0 Ethibond su. ture whose holding arms are longitudinal, parallel t o t h e tension with the tendon. It i s a quadrilat. eral suture with small loops at each corner, The suture ends up at the lac. erated end of the tendon, placing the knot within the repairi This suture is placed in the volar half of the tendon to minimize damage tothe blood supply from the vincula entering the dorsal surface.
POSTOPEFIATIVE CARE To limit the formation of peritendinous adhesions, we use a modified Kleinert therapy for the first 4 weeks if tendon repair is necessary. If no repair was performed, we allow immediate protected active motion. If tenorrhaphy is undertaken, the wrist and hand are immobilized with a dorsal plaster splint with the wrist in 30 ° of flexion, the metacarpophalangeal joints in 45 ° of flexion, and the interphalangeal joints in minimal flexion. Kleinert traction involves the use of rubber bands to allow active extension and passive flexion of the digits. 33 After placing the patient in a dorsal blocking splint, rubber bands are attached to the fingernails of all digits (excluding the thumb) irrespective of how many tendons were lacerated. The rubber bands are attached to the volar portion of the dressing. During the first 4 postoperative weeks, the patient is instructed to flex passively the digit to the distal palmar crease 25 times each hour. We also have used Duran therapy in the treatment of partial flexor tendon injuries. If this protocol is chosen, the patient is placed into a dorsal blocking splint with the metacarpophalangeai joints flexed to 70 ° and the interphalangeal joints at neutral. Duran therapy involves controlled passive digital[ mobilization within a specific range, which allows 3 to 5 m m of: tendon excursion. 34 Patients perform these passive exercises immediately and continue them daily for four sets of 10 repetitions of each tendon within the dorsal blocking splint. 70
Splinting is discontinued at 4 weeks and active digital flexion and extension are permitted.
RESULTS In the first clinical study of partially lacerated flexor tendons, Wray et al9 treated 17 of 20 partial tendon lacerations (25% to 95% of cross-sectional area) without repair and with early active motion. Sixteen of these patients obtained excellent results and reported no episodes of triggering, rupture, or entrapment. 9 In a follow-up report, 26 patients with partial tendon lacerations (median cross-sectional lacerated area of 60%) were treated with nonsuturing of the tendons followed by early mobilization of the digit. Twenty-three of 26 patients obtained excellent function, one patient obtained good to excellent function, and one patient achieved a fair functional result. One patient did experience triggering, which spontaneously resolved. 35 Schienker et al9 described three patients with complications of untreated partial flexor tendon lacerations, entrapment, rupture, and triggering. They recommended tenorrhaphy for lacerations of greater than 25% to prevent this morbidity. 8 McGeorge and Stilwel136 followed up with a clinical study of tenorrhaphy versus non_repair in tendons of various degrees of laceration. The nonrepair group consisted of 12 patients with an average tendon division of BALK AND SOTEREANOS
54% (range 20% to 60%). The repair group consisted of six patients with an average tendon division of 36% (range 20% to 70%). In the nonrepair group, all oblique and uneven lacerations were trimmed to prevent entrapment and ensure smooth gliding. In both groups, the sheath was closed and an early mobilization program was followed postoperatively. They showed t h a t all patients in the nonrepair group achieved excellent range of motion and that tenorrhaphy significantly reduces pinch grip. They concluded that tenorrhaphy should not be performed in flexor tendon injuries involving 60% or less of their crosss e c t i o n a l area. 36 B a s e d o n o u r l a b o r a t o r y d a t a a n d clinical e x p e r i e n c e , w e d o n o t r e p a i r l a c e r a t i o n s w i t h less t h a n 60% c r o s s - s e c t i o n a l i n v o l v e m e n t u n l e s s t r i g g e r i n g or e n t r a p m e n t occurs. We b e l i e v e these t e n d o n s are c a p a b l e of w i t h s t a n d i n g e a r l ~ n o n s t r e n u o u s active r a n g e of m o t i o n . T e n d o n l a c e r a t i o n s w i t h less t h a n 60% c r o s s - s e c t i o n a l i n v o l v e m e n t are r o u t i n e l y r e p a i r e d a n d r e h a b i l i t a t e d i n a s i m i l a r f a s h i o n as complete t e n d o n lacerations.
COMPLICATIONS AND MANAGEMENT Complications of the management of partial flexor tendon lacerations include triggering, entrapment, bowstringing, rupture, infection, and stiffness. Triggering and entrapment require reexploration to determine the offending cause. Further debridement of tendon edges or sheath excision may be indicated. Debridement requires careful attention to preserving all annular pulleys to avoid bowstringing and loss of motion. All work should be performed in cruciate windows. Rupture of partial tendon lacerations is rare provided that a protected postoperative regimen is strictly followed. Complete ruptures of partial flexor tendon tears must undergo formal tenorrhaphy followed by protected early mobilization. Infection likewise is rare, but requires irrigation and debridement of the tendon sheath and all peritendinous tissues followed by a course of antibiotics. Stiffness, typically restriction of extension, is treated with dynamic splinting. If this is unsuccessful tenolysis may be indicated.
CONCLUSIONS The management of partial flexor tendon lacerations remains controversial. Although some clinicians recommend no suturing of any partial laceration, 9,35others recommend tenorrhaphy even for lacerations of only 25% of crosssectional area. 8 This disparity of opinions, likewise, has manifested itself in the varied treatment of these injuries by hand surgeons recently s u r v e y e d . 29 Recent studies show that tendons with up to 60% involvement may be able to tolerate an early active mobilization program. 11In addition, tenorrhaphy does not significantly improve gliding function in tendons with up to 70% laceration. 1° For those reasons, we recommend tenorrhaphy only for those tendons with greater than 60% l a c e r a t i o n of c r o s s - s e c t i o n a l area or t h o s e t h a t trigger. Meticulous surgical technique and early protected mobiliz a t i o n p r o v i d e the b e s t c h a n c e for a n o p t i m a l result. PARTIAL FLEXOR DIGITORUM PROFUNDUS LACERATIONS
REFERENCES 1. Kleinert HE: Should an incompletely severed tendon be sutured? The voice of polite dissent. Plas Reconstr Surg 57:236, 1976 (letter) 2. Bishop AT, Cooney WP, Wood MB: Treatment of partial flexor tendon lacerations: The effect of tenorrhaphy and early protected mobilization. J Trauma 26:301-12, 1986 3. Reynolds B, Wray RC, Weeks PM: Should an incompletely severed tendon be sutured? Plas Reconstr Surg 57:236-238, 1976 4. Wray RC, Ollinger H, Weeks PM: Effects of mobilization on tensile strength of partial tendon lacerations. Surg Forum 26:557-558, 1975 5. Al-Qattan MM, Posnick JC, Lin KY: Triggering after partial tendon laceration. J Hand Surg [Br] 18:241-246,1993 6. Frewin PR, Scheker LR: Triggering secondary to an untreated partially cut flexor tendon. J Hand Surg [Br] 14:419-421,1989 7. Janecki CJ: Triggering of the finger caused by flexor tendon laceration. J Bone Joint Surg Am 58:1174-1175,1976 8. Schlenker JD, Lister GD, Kleinert HE: Three complications of untreated partial tendon laceration of flexor tendon--Entrapment, rupture, and triggering. J Hand Surg [Am] 6:392-396,1981 9. Wray RC, Holtmann B, Weeks PM: Clinical treatment of partial tendon lacerations without suturing and with early motion. Plas Reconstr Surg 59:231-234, 1977 10. Boardman III ND, Morifusa S, Chan SS, et al: Effects of tenorrhaphy on the gliding function and tensile properties of partially lacerated canine digital flexor tendons. J Hand Surg, 1997 (Submitted for publication) 11. McCarthy DM, Tramaglini DM, Chan SS, et al: Effects of partial laceration on the structural properties of the canine FDP tendon: An in vitro study. J Hand Surg [Am] 20:795-800, 1995 12. Seiler III JG, Gelberman RH, Williams CS, et al: Autogenous flexortendon grafts. J Bone Joint Surg Am 75:1004-1014, 1993 13. Gelberman RH, Woo SL-Y,Amiel D, et ah Influences of flexor sheath continuity and early motion on tendon healing in dogs. J Hand Surg [Am] 15:69-77,1990 14. Matthews P, Richards H: Factors in the adherence of flexor tendons after repair. J Bone Joint Surg Br 58:230-236, 1976 15. McDowell CL, Snyder DM: Tendon healing: An experimental model in the dog. J Hand Surg [Am] 2:122-126, 1977 16. Noguchi M, Seiler III JG, Gelberman RH, et ah In vitro biomechanical analysis of suture methods for flexor tendon repair. J Orthop Res 11:603-611, 1993 17. Peterson WW, Manske PR, Dunlap J, et ah Effect of various methods of restoring flexor sheath integrity on the formation of adhesions after tendon injury. J Hand Surg [Am] 15:48-56,1990 18. Wade PJF, Muir IFK, Hutcheon LL: Primary flexor tendon repair: The mechanical limitations of the modified Kessler technique, J Hand Surg [Br] 11:71-6,1986 19. Wade PJF, Wetherell RG, Amis AA: Flexor tendon repair: Significant gain in strength from the Halstead peripheral suture technique. J Hand Surg [Br] 14:232-235,1989 20. Wray RC, Ollinger H, Weeks PM: Effects of mobilization on tensile strength of partial tendon lacerations. Surg Forum 26:557-558, 1975 21. Lundborg G: Experimental flexor tendon healing without adhesion formation--New concept of tendon nutrition and intrinsic healing mechanisms. The Hand 8:235-238, 1976 22. Manske PR, Whiteside LA, Lesker PA: Nutrient pathways to flexor tendons using hydrogen washout technique. J Hand Surg [Am] 3:32-36, 1978 23. Manske PR, Whiteside LA, Lesker PA: Nutrient pathways to flexor tendons of chickens using tritiated proline. J Hand Surg [Am] 3:352-357, 1978 24. Manske PR, Gelberman Rid, Vandelberg JS, et al: Intrinsic flexortendon repair. J Bone Joint Surg Am 66:385-396, 1984 25. Schuind F et ah Flexor tendon forces: In vivo measurements. J Hand Surg [Am] 17:291-298,1992 26. Bright DS, Urbaniak JR: Direct measurements of digital flexor tendon tension: application to flexor tendon surgery. Orthop Trans 1:4-5, 1977 27. Cooney WP, An KN, Chao EYS, et ah Direct measurement of tendon forces in the hand, in 32nd annual meeting of the Orthopaedic Research Society. New Orleans, LA, Adept Printing, 1986
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28. Weightman B and Amis AA: Finger joint force predictions related to design of joint replacements. J Biomed Eng 4:19%205, 1982 29. McCarthy DM, Boardman III ND, Tramaglini DM, et aI: Clinical management of partially lacerated digital flexor tendons: A survey of hand surgeons. J Hand Surg [Am] 20:273-275, 1995 30. Weeks PM: Invited comment. J Hand Surg 6:396-397, 1981 31. Bruner JM: The zig-zag volar digital incision for flexor tendon surgery. Plas Reconstr Surg 40:571-574, 1967 32. Grewal R, Sotereanos DG, Rao U, et al: Bundle pattern of the flexor digitorum profundus tendon in Zone II of the hand: A quantitative assessment of the size of a laceration. J Hand Surg [Am] 21:978~983, 1996
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33. Lister GD, Kleinert HE, Kutz JE, et al: Primary flexor tendon repair followed by immediate controlled mobilization J Hand Surg EAm] 2:441-451. 1977 34. Duran RJ, Coleman CR, Nappi JF, et ah Management of flexor tendon lacerations in zone 2 using controlled passive motion postoperatively, in Hunter J, Schneider L. Mackin E, et al (eds): Rehabilitation of the Hand, ed 3 St Louis. MO, Mosby~Yearbook, 1990, pp 410-413 35. Wray RC and Weeks PM: Treatment of partial tendon lacerations. The Hand 12:163-166, 1980 36. McGeorge DD, Stilwell JH: Partial flexor tendon injuries: To repair or not, J Hand Surg [Br] 17:176-177, 1992
BALK AND SOTEREANOS