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Treatment of flexor tendon injuries: Surgeons' perspective
Treatment of Flexor Tendon Injuries: Surgeons' Perspective John S. Taras, MD
Clini cal A ssistant Professor Division of Hand Surgery Department of Orthopaedic Surgery Thomas Jefferson University Philadelphia, Pennsylvania; The Philadelphia Hand Cent er Philadelphia, Penn sylvania
Marc
J. Lamb, MD
The Philadelphia Hand Center Philadelphia, Pennsylvania
estor ation of digital function following R flexor tendon injury continues to challenge the hand surgery and therapy communities. Stiff-
ness and scarring leading to functional impairment continue to frustrate the most experienced surgeons, therapists, and compliant patients. Despite efforts to improve the results of flexor tendon repairs, restrictive adhesions affixing the injured tendon to the flexor tendon sheath continue to compromise functional recovery more than any other problem. Joint contracture and repair rupture present additional obstacles to a successful outcome following repair of flexor tendons. The irreparable tendon and tendon sheath requiring reconstruction remain a troublesome clinical presentation. This paper reviews flexor tendon literature defining today's understanding of the flexor tendon system's response to injury and surgical reconstruction. New techniques will continue to evolve, each having the goal of promoting tendon gliding and limiting postoperative adhesions. As the new millennium approaches, we edge closer to the goal of predictably restoring normal hand function after flexor tendon injury.
This paper is followed, on p . 149, by a paper presenting a hand therapist's commentary on the same subject. Correspondence and reprint requests to John S. Taras, MD, The Philadelphia Hand Center, PC, 834 Chestnut Street, Suite G114, Philadelphia, PA 19107.
ABSTRACT: Medical researcher s continue to exp lore the flexor tendon's response to injury and repair. In recent years, hand surgery and therapy publications have focused on the biomechanics of suture techniques and the benefits of early postoperative motion on su rgically repaired flexor tendons. Lab oratory and clinical studies ha ve sh own that s tronger sutu re techniques can withstand the strain of immediate acti ve m oti on w ithout a significant risk of tendon rupture or gap forma tion . Newl y proposed therapy techniques and anatomic stud ies defining the effects of wrist and digital position on tendon excu rsion share the goals of achieving early motion and reducing restrictive adhesions. Clinical studies have evaluated th e va rious imaging modalities used to diagnose postoperative ad hesions. Other clinical surveys have detailed the use of pedicled autograft and allograft tendons in staged reconstruction. H istologic and immunologic researchers have concentrated on eellular activation patterns followin g tendon injury and the effects of pharmacologic agents, such as hyaluronan and aprotinin, on tendon healing and adhesion formation. J HAND THER 12:141-148, 1999.
HISTOLOGIC AND IMMUNOLOGIC FEATURES OF FLEXOR TENDON INJURY Histologic and immunologic studies have advanced the contemporary understanding of tendon healing and adhesion formation. Using monoclonal antibodies to localize specific inflammatory markers, Khan et al.' have determined that the synovial sheath and epitenon are more reactive than the endotenon in the early period after tendon injury. Using a rabbit model, these authors found that the synovial lining is a dominant factor in the scarring response to injury. Wiig et a1. 2 describe the differences in cellular activities between tendons and synovial sheaths during healing. In a separate study they also describe the effects of hyaluronan on cell proliferation and collagen synthesis.' Wiig et a1. demonstrate in vitro that hyaluronan does not affect the synthesis of matrix components necessary for tendon healing but does inhibit fibroblast proliferation, and a reduction in fibroblasts could reduce adhesion formation. Their subsequent in vivo study, however, reveals that low concentrations of hyaluronan exert no effect on tendon healing or ad hesion formation in a rabbit model. Apparently the hyaluronan gel diffuses too rapidly to have a clinically significant effect in reducing adhesions. A study by Komurcu et a1. 4 attempts to quantify the effect of aprotinin and sheath repair on adhesion formation in lacerated rabbit flexor tendons. April-June 1999
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Utilizing work-of-flexion values to measure adhesion formation, Komurcu et al. find that aprotinin decreases adhesion formation less than primary sheath repair does and much less than sheath repair and aprotinin application combined do. Greenough" finds that pulsed electromagnetic fields induce neither tendon healing nor adhesion formation. Abrahamsson" concludes that longer operative times and wider surgical exposures increase cell proliferation in the rabbit tendon, but irrigation can counteract the negative effects on exposed flexor tendons by preventing tissue desiccation. It is likely that at some time in the future the means will exist to chemically modify the tendon healing environment to limit adhesions and promote healing. The only method proved to decrease adhesion formation thus far is the encouragement of motion between the tendon and its sheath.
ACUTE INJURIES Active Mobilization Recent research indicates that active mobilization after primary tendon repair yields greater and more reliable tendon excursion than passive mobilization. Studies by Kleinert et al.." Strickland and Glogovac," and Chow et al." describe postoperative passive flexion which was usually combined with active extension therapy regimens following flexor tendon repair. These authors describe improved range of motion compared with the historically disappointing results achieved following immobilization, and attribute these findings to enhancement of tendon gliding. Variations of the passive flexion and active extension hand therapy regimen have become the treatment standard following primary flexor tendon repair in compliant patients, yet such protocols have not elicited uniformly favorable recovery of motion. Schenck and Lenhart" employed Chow's active extension and rubberband passive flexion regimen in their series of primary flexor tendon repairs. Their results contrast sharply with Chow's encouraging report, which cites 82% good and excellent results. Schenck and Lenhart report that only a minority (48%) of their patients achieved good or excellent results. The authors state that typical primary flexor tendon repairs may fall far short of reliably restoring normal function. Silfverskiold" evaluated the efficacy of passive flexion and active extension after primary flexor tendon repair. In this study, the author measures tendon excursion during the early mobilization period by tagging tendon repairs with metallic sutures. He concludes that passive flexion techniques can produce tendon excursion approaching that of active flexion, but the variation of excursion among individuals is great. He cautions that not all tendons glide to the same degree after primary repair, and restrictive adhesions are more likely to form in the absence of gliding. Silfverski6ld's study supports the belief that early active flexion should pro142
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duce greater tendon excursion than passive flexion alone.
Biomechanics and Physiology of Tendon Repairs The rationale promoting active mobilization of repaired flexor tendon lacerations developed from the biomechanics and physiology of the healing sutured tendon. A canine study by Urbaniak et al." provides evidence that repaired tendons lose nearly half their initial repair strength within one week of immobilization. After publication of this study, researchers believed the tensile strengths of common repair techniques were insufficient to support active tendon mobilization reliably. To assuage the fear of rupture, surgeons have increased the repair site's ability to withstand the forces transmitted from muscle to bone by devising repair techniques using more suture material. The most common of these applications increase the number of suture strands passed across the repair. A human cadaveric work-of-flexion study by Aoki et al.'? posits a relationship between the quantity of suture used in the repair and the resistance to gliding. According to these authors, the increased resistance to tendon gliding measures 4.8% in the two-strand modified Kessler repair, 6.5% in the lateral margin Becker repair, and 19.3% in the six-strand Savage repair. Bulkier experimental repair techniques-including the :internal tendon splint, external mesh sleeve, and dorsal tendon splint-oppose tendon gliding up to 44% more than the simpler constructs. This study does not consider elements such as tissue swelling and edema; however, work of flexion clearly increases in direct proportion to the amount of suture used to achieve the repair. The work of Kubota et al." elucidates the individual effects of motion and tension on partially transected and repaired chicken flexor tendons. Histologically, the alliance of motion and tension promotes the greatest increase in cellular activity, while the absence of both components generates the least activity. Independently, motion or tension does induce intermediate changes in cellular activity, but less than when the two are combined. Thus, the collaborative efforts of motion and tension appear to enhance the tendon's response to injury. Aoki et al." published a study of the biomechanical and histologic characteristics of canine flexor tendon repairs subject to early active motion. The weaker Kessler repairs rupture in 89% of his specimens; however, none of the Savage or dorsal tendon splint repairs rupture. Most significantly, successful tendon repairs stressed during the healing process appear to lose little initial repair strength when tested for gap formation and tensile strength five days after repair. Aoki et al. note that initial repair strength returns by ten days following repair, and tendons subject to tensile stress in an active-motion postoperative regimen maintain their strength much better than immobilized tendons.
Separate studies presented by Komanduri et al." and Soejima et al." examine core suture placement in cadaveric flexor tendons to determine whether dorsal or volar position influences repair strength. Soejima et al. harvested repaired tendons before stressing them to longitudinal tensile failure. In his survey, dorsally placed suture provides 26.5% greater strength prior to failure than volarly placed suture. Komaduri et al. repaired and tested specimens within their tendon beds, preserving in vivo angulation, loading, and frictional interference. In his curvilinear model, dorsal suture placement proves nearly twice as strong as volar placement. Following reports that epitendinous suture techniques augment repair strength significantly, Diao et al." investigated the depth of placement of running epitendinous suture. His findings indicate that deep suture placement is nearly 80% stronger than superficial placement when used to complement a Kessler core suture. The Diao technique, combining deep epitendinous suture and a Kessler core suture, can tolerate loads up to 40 newtons, but the authors do express concern that this technique may not provide adequate support for an active mobilization program. A study of core suture caliber by Taras et al." indicates that increasing suture gauge significantly augments repair strength. Suture rupture is the cause of failure of the Kessler, Bunnell, and doublegrasping repairs constructed with 4-0 braided polyester in this study. For these two-strand techniques, the core suture strength is independent of technique. As suture gauge increases, however, the technique's grasping characteristics become more significant. Taras et al. report that Kessler repairs pull out of the tendon ends more easily than do Bunnell or double-grasping sutures. In this study, the combination of a 3-0 double-grasping core suture and the cross-stitch epitendinous repair developed by Silverskiold withstands an average ultimate tensile strength of 72 newtons. Theoretic
models indicate that this construct does afford sufficient strength to support an active mobilization protocol. Evans and Thompson" developed a theoretic model determining force application at the repair site. Assuming a posture of 20° wrist extension, 83° metacarpophalangeal (MP) flexion, 75° proximal interphalangeal (PIP) flexion, and 40° dorsal interphalangeal flexion, an external load of 50 g exerts 41 g of tension on the flexor digitorum profundus (FDP) and 605 g of tension on the flexor digitorum superficialis (FDS). Increasing flexion angles to 85° MP (2° increase), 95° PIP (200 increase), and 750 DIP (350 increase) causes a sharp tension increase of 1,650 g on the FDP and 2,050 g on the FDS. Thus, even minimal deviation from the prescribed posture increases the load beyond the repair's tensile capacity. The authors caution against extreme joint positions during active motion rehabilitation exercises when the repair technique might not support these forces.
Clinical Series Recent clinical studies assessing flexor tendon repairs treated with active postoperative protocols and standard passive flexion-active extension protocols demonstrate more good and excellent outcomes than those utilizing passive tendon gliding alone. Baktir et al." prospectively compared the Kleinert rubberband passive flexion-active extension method with an early active mobilization method to treat zone 2 flexor tendon injuries. The percentage of good and excellent results was larger (85% compared to 78%) and the mean grip strength greater (90% versus 84%) in the active mobilization group. Of the 88 repairs cited in this study, two early ruptures occurred in each group. Elliott et al." applied a controlled active motion program to primary repair of flexor tendon lacerations. His repair technique combined a 3-0 or 4-0 Kessler monofilament core suture with a 6-0 run-
FIGURE 1. Left, The cross-stitch epitendinous technique developed by Silfoerskiold. Right, The Taras double-grasping core suture technique. (Reprint ed, with permission, from Taras IS , Skahen IR III, Raphael IS , et al. The double-grasping and crossstitch for acute flexor tendon repair: applications with active motion. In: Schneider LH, Taras IS , eds. Atlas of the Hand Clinics. 1996;1(1):13-28. Copyright 1996, W B Saunders Co.) April-June 1999
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FIGURE 2. The Strickland Indiana method of flexor tendon repair. (Reprinted, with permission, from Schneider LH, Taras IS, eds. Atlas of the Hand Clinics. 1996;1(1):77. Copyright 1996, W B Saunders Co.)
ning epitendinous nylon suture for FDP and flexor pollicis longus (FPL) lacerations. For FDS repairs, he used a 4-0 or 5-0 nylon mattress stitch. With this regimen 5.8% of the fingers and 16.6% of the thumbs had ruptures. Of the 63 fingers with zone 2 lacerations, 79.4% demonstrated good or excellent results. Compared with earlier series reporting passive flexion and active extension regimen results, this study's rupture rate is not appreciably higher in digits other than the thumb. Silfverskiold and May" have offered a new ep)
FIGURE 3. Top, The Sandow modified-Savage single-cross grasp six-strand flexor tenorrhaphy technique prior to knot tying. Bottom, The completed repair. (Reprinted, with permission, from Sandow MI, McMahon MM. Single-cross grasp six-strand repair for acute flexor tenorrhaphy. In: Schneider LH, Taras IS, eds. Atlas of the Hand Clinics. 1996;1(1):4164. Copyright 1996, W B Saunders Co.) 144
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The six-strand loop suture technique for flexor tendon repair, after Lim. (Reprinted, with permission, from Lim BH, Tsai T-M. The six-strand technique for flexor tendon repair. In: Schneider LH, Taras IS, eds. Atlas of the Hand Clinics. 1996; 1(1):65-76. Copyright 1996, W B Saunders Co.)
itendinal suture technique, the cross-stitch, in his study to repair 55 digits with zone 2 flexor tendon lacerations. The cross-stitch creates an external weave resembling a Chinese finger trap (Figure 1, left). The repair technique combines the cross-stitch epitendinal suture with a 4-0 braided Kessler core stitch. The postoperative regimen comprises active extension and passive and active flexion. Two repairs of the 55 (3.6%) ruptured. The mean active DIP and PIP joint motion six months after surgery measured 157° (71% excellent and 25.5% good). These results represent an improvement of 15° motion over results obtained at the same clinic with a passive flexion and active extension regimen. Taras et a1. 21 applied a program of active and passive flexion to 14 digits with flexor tendon laceration repaired using Silfverskiold's cross-stitch combined with a 3-0 braided polyester core suture incorporating an extra grasping throw at each corner of the stitch (Figure 1, right). This series reports an 87% recovery of motion with no ruptures. The therapy protocol starts with place-and-hold exercises on the day following surgery, progresses to active tendon-gliding exercises at three weeks, and initiates resistive exercises by six weeks. The Strickland four-strand suture technique pairs a modified Kessler core stitch of 3-0 braided synthetic suture with a horizontal mattress stitch and a 6-0 nylon epitendinous suture (Figure 2). Thirty-four patients with zone 1 and zone 2 injuries completed an active motion physiotherapy program. Of these patients, nine recovered more than 150° interphalangeal motion, 17 reclaimed 125° to 149° interphalangeal motion, 9 recovered 90° to 124° motion, and 2 recovered less than 90° motion when discharged from therapy. Active interphalangeal motion averaged 130°. Long-term follow-up of 19 digits in this series shows a 19° improvement of interphalangeal joint motion compared with inter-
phalangeal motion when discharged from formal hand therapy. This represents a significant improvement over the same authors' reports of results from a passive flexion and active extension regimen. Sandow and Mclvlahon" and Lim and Tsae3 presented clinical series of different six-strand core suture techniques. Sandow and McMahon modify the Savage technique by placing a single-cross grasp for fixation of each suture limb (Figure 3). They also describe use of a new tendon-holding device that simplifies this technically demanding suture technique. Twenty-three tendons in 18 patients with zone 2 repairs underwent a program of active mobilization. Seventy-eight percent received an excellent or good rating using the Strickland and Glogovac criteria. Mean active interphalangeal motion measured 135°. This series reported no ruptures. Lim and Tsai presented the results of a loop suture technique developed by Tsai to construct a six-strand repair (Figure 4). Thirty-two digits unApril-June 1999
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derwent a rehabilitation regimen employing controlled active and passive motion. One patient suffered a tendon rupture. When graded, 13 (40.5%) achieved more than 132° of active interphalangeal motion, 13 (40.5%) regained 88° to 13r active interphalangeal motion,S (16%) gained 48° to 87" active interphalangeal motion, and excluding the rupture no patients gained less than 47° active interphalangeal motion.
PARTIAL TENDON LACERATION AND RECONSTRUCTION Anatomic studies further defined the structure and dynamic interaction of the flexor tendons and pulley system. Grewal et al. 24 proposed a more accurate method of assessing partial tendon lacerations in zone 2 based on the percentage area of the radial and ulnar bundles of the profundus tendon. This new method factors the cross-sectional area of the profundus tendon and the intratendinous bundles at various levels in zone 2. This formula provides a patient-specific method by which clinicians can assess accurately and easily the size of a partial tendon laceration. Most of the current literature espouses surgical repair using a core suture for tendon lacerations through more than 60% of the flexor tendon. Lacerations of less than 30% do not warrant repair. The recommendation for management of tendon lacerations encompassing 30% to 60% of the tendon is less clear. Flap lacerations that result in triggering or impingement may require repair or debridement, regardless of their size. Preference surveys indicate that the majority of surgeons repair midrange partial lacerations; however, Bishop et a1. 26 and Cooney et a1. 27 report that suturing a partially lacerated tendon can be detrimental to tendon strength.
Diagnosis Adhesions are the most common tendon healing complication. The difficulty distinguishing restrictive adhesions from tendon rupture during the early postoperative period has compelled investigators to seek better methods of visualizing this perplexing clinical situation. Matloub et al.28 surveyed 16 tendons less than eight weeks after repair, each carrying a clinical diagnosis of rupture. In their study, clinical examination yields a 60% accuracy in diagnosis, while magnetic resonance imaging correctly distinguishes adhesions from ruptures in all cases. This study complements prior work by Calandruccio and Steichen" and Drape et a1.,3O who promote magnetic resonance imaging to evaluate adhesion formation, tendon rupture, and gap formation at repair sites. Bare-handed rock climbing has increased in popularity during recent years, and hazards of the sport, including rupture of the pulley system, are more widely encountered today. In this sport one 146
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or two fingers may bear the climber's total body weight. Le Viet et a1.31 reported seven cases of pulley rupture confirmed by computed tomography (CT). In each case, CT scanning visualizes the rupture and establishes a correct diagnosis. For pulley ruptures, CT scanning clearly illustrates the dynamic images of the digits straining against resistance and the resultant bowstringing. Compared with other clinical diagnostics, including standard radiography, ultrasound, and magnetic resonance imaging, CT scanning provides an accurate, easy, and cost-effective imaging procedure to diagnose digital pulley rupture.
The Pulley System Several recent dynamic human cadaveric studies assessed the efficiency of the flexor tendon pulley system.32-34 Evaluating tendon excursion, force, and work, Rispler et al. 34 report that the absence of an A4 pulley results in the largest loss of efficiency of the individually tested pulleys. They report that the loss of a single minor pulley (AI or AS) results in an insignificant loss of efficiency, whereas absence of a major pulley is detrimental to system efficiency as a whole. They report that absence of an A4 causes an 85% loss of work and excursion, and loss of an AZ results in an excursion difference of 94%. A mechanical analysis of the palmar aponeurosis pulley performed by Phillips and Mass" reveals that isolated sectioning of the palmar aponeurosis pulley alone does not significantly change any efficiency parameters. Absence of the palmar aponeurosis and loss of either or both proximal annular pulleys (AI, AZ), however, demonstrates a significant decrease in excursion efficiency. Phillips and Mass stress that the palmar aponeurosis pulley should be considered as important as the annular and cruciate flexor tendon pulleys. Hamman et aP2 examined the effects of digital pulley excision and loss of the profundus tendon on the efficiency of the superficialis tendon using a human cadaver model. They conclude that the A2 and A3 are the most important pulleys for superficialis function, and the profundus is necessary for optimal tendon excursion efficiency.
Tendon Grafts The indications and technique for primary and staged tendon grafting are well established. Infections, adhesions, concurrent neurovascular and osseous injuries, tendon rupture, and patient noncompliance can compromise the result of primary flexor tendon repair. Tendon grafting is the standard procedure for digits when direct repair is not feasible or has failed. The common donor tendons, including the palmaris, plantaris, and toe extensors are extrasynovial grafts. Alternative procedures have recently been introduced to ameliorate clinical situations where standard tendon grafting techniques are not practical.
Naam" reported the use of pedicled flexor digitorum superficialis tendon as a graft in the second stage of reconstruction in 33 digits. On follow-up 3.7 years after surgery, 64% of patients achieved good-to-excellent results, and three of the 33 patients required tenolysis. Patients older than 25 years who had significant soft tissue injuries or who were noncompliant with postoperative therapy demonstrated poorer results. Noguchi et al." explored the benefits of using an intrasynovial autograft such as the superficialis tendon with an adult canine model. They state that intrasynovial tendon grafts exhibit superior gliding function compared with extrasynovial grafts after six weeks of healing. Human composite flexor tendon allografting provides one alternative to salvage a multiple operated digit. Asencio et al." presented two cases followed for five years after composite flexor tendon allografts. Both patients achieved a real functional improvement without any complications; thus, the authors believe that allografting can restore good function without synovitis, infection, or secondary rupture. Issues regarding antigenicity and contagious disease transfer do warrant continued caution regarding the use of allograft tendon. Gabuzda et al." investigated the strength of end-weave repair and assessed the number of weaves on pull-out strength with a human cadaver model. In their survey, they compare the efficacy of the standard mattress suture with a multiple-pass technique doubling the amount of suture material used in the mattress technique. The authors reach two conclusions: First, the results demonstrate a clear relationship between pull-out strength and the number of weaves and suture material used in both methods. Second, the multiple-pass technique imparts stronger pull-out resistance per weave than does the mattress suture. Gabuzda et al. estimate the tensile strength of the multiple-pass end-wave repairs using three, four, or five weaves to be at least 40 to 50 newtons.
CONCLUSION Recent research investigating flexor tendon injuries, surgical repair techniques, and postoperative therapy protocols has refined the results of flexor tendon repair so that satisfactory outcomes can be routinely expected. Future clinical studies will likely show that suture techniques can withstand the forces generated by early active motion therapy protocols. The greater amount of tendon excursion performed with active motion therapy will decrease the significance of restrictive adhesions that currently compromise functional recovery. Basic science advances have enhanced today's understanding of the flexor tendon pulley system's dynamic anatomy. Comprehension of tendon healing will guide future therapy and splinting protocols and may lead to a pharmacologic agent that improves tendon gliding.
REFERENCES 1. Khan U, Edwards J, McGrouther D. Patterns of cellular activation after tendon injury. J Hand Surg. 1996;21B:813-20. 2. Wiig M, Abrahamson, Lundborg G. Effects of hyaluronan on cell proliferation and collagen synthesis: a study of rabbit flexor tendons in vitro. J Hand Surg. 1996;21A:599-604. 3. Wiig M, Abrahamsson S, Lundborg G. Tendon-repair cellular activities in rabbit deep flexor tendons and surrounding synovial sheaths and the effects of hyaluronan: an experimental study in vivo and in vitr o. J Hand Surg. 1997; 22A:818-25. 4. Komurcu M, Akkus 0, Basbozkurt M, et al. Reduction of restrictive adhesions by local aprotinin application and primary sheath repair in surgically traumatized flexor tendons of the rabbit. J Hand Surg. 1997;22A:826-32. 5. Greenough C. The effect of pulsed electromagnetic fields on flexor tendon healing in zone 2 of the hand: a quantitative assessment of the size of a laceration. J Hand Surg. 1996; 21A:978-83. 6. Abrahamsson S. Exposure to air during surgery inhibits cellular activity in flexor tendons. J Hand Surg. 1996;20B:299302. 7. Schenck R, Lenhart D. Results in zone 2 flexor tendon lacerations treated by the Washington regimen. J Hand Surg. 1996;21A:984-7. 8. Silfverskiold KL. Tendon excursion after flexor tendon repair in zone II: results with a new controlled motion program. J Hand Surg. 1993;18A:403-1O. 9. Urbaniak JR, Cahill JD, Mortenson RA. Tendon suturing methods: analysis of tensile strengths. In: American Academy of Orthopedic Surgeons: Symposium on Tendon Surgery in the Hand, 1975. Airlie, Va.: AAOS, 1975:70-80. 10. Aoki M, Manske P, Pruitt D, Larson BJ. Work of flexion after tendon repair with various suture methods. J Hand Surg. 1995;20B:310-3. 11. Kubota H, Manske P, Aoki M, Pruitt DL, Larson BJ. Effect of motion and tension on injured flexor tendons in chickens. J Hand Surg. 1996;21A:456-63. 12. Aoki M, Kubota H, Pruitt D, Manske PRo Biomechanical and histological characteristics of canine flexor tendon repair using early postoperative mobilization. J Hand Surg. 1997;22A:107 -14. 13. Komanduri M, Phillips C, Mass DP. Tensile strength of flexor tendon repairs in a dynamic cadaver model. J Hand Surg. 1996;21A:605 -11. 14. Soejima 0, Diao E, Lotz J, Hariharan JSL. Comparative mechanical analysis of dorsal versus palmar placement of core sutures for flexor tendon repair. J Hand Surg. 1995;20A:8017. 15. Diao E, Hariharan J, Soejima 0, Lotz J. Effect of peripheral suture depth on strength of tendon repairs. J Hand Surg. 1996;21A:234-9. 16. Taras JS, Raphael JS, Marczyk Sc, et al. Evaluation of suture caliber in flexor tendon repair: applications for active motion. Jefferson Orthop J. 1995;24:15-9. 17. Evans RB, Thompson DE. The application of force to the healing tendon. J Hand Ther. 1993;6:266-84. 18. Baktir A, Turk C, Kabak S, et al. Flexor tendon repair in zone 2 followed by early active mobilization. J Hand Surg. 1996;21B:624-8. 19. Elliot D, Moiemen NS, Flemming AFS, Harris SB, Foster AJ. The rupture rate of acute active flexor tendon repairs mobilized by the controlled active motion regimen. J Hand Surg. 1994;19B:5:607-12. 20. Silfverskiold KL, May EJ. Flexor tendon repair in zone II with a new suture technique and an early mobilization program combining passive and active motion. J Hand Surg. 1994;19A:53-60. 21. Taras JS, Skahen J, Raphael J, Marczyk S, Bauerle W. The double-grasping and cross-stich for acute flexor tendon repair. In: Taras JS, Schneider LH (eds). Atlas of the Hand Clinics. Philadelphia, Pa .: W B Saunders, 1996:13-27. 22. Sandow MJ, McMahon MM . Single-cross grasp six-strand repair for acute flexor tenorrhaphy. In: Tarras JS, Schneider LH (eds). Atlas of the Hand Clinics. Philadelphia, Pa .: W B
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Saunders, 1996:41-64. 23. Lim BH, Tsai T-M. The six-strand technique for flexor tendon repair. In: Taras JS, Schneider LH (eds). Atlas of the Hand Clinic. Philadelphia, Pa.: W B Saunders, 1996:65-77. 24. Grewal R, Sotereanos DG, Rao U, Herndon JH, Woo S1. 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. 1996;21(6):978-83. 25. Strickland JS. The Indiana method of flexor tendon repair. In: Taras JS, Schneider LH (eds). Atlas of the Hand Clinics. Philadelphia, Pa.: W B Saunders, 1996:77-103. 26. Bishop AT, Cooney WP, Wood MB. Treatment of partial flexor tendon lacerations: the effect of tenorrhaphy and early protected mobilization. J Trauma. 1986;26(4):301-12. 27. Cooney WP, Weidman K, Malo D, Wood MB. Management of acute flexor tendon injury in the hand. American Academy of Orthopedic Surgeons Instructional Course Lecture. 1985;34:373-81. 28. Matloub H, Dzwierzynski W, Erikson S, Sanger JR, Yousif NJ, Muoneke V. Magnetic resonance imaging scanning in the diagnosis of zone 2 flexor tendon rupture. J Hand Surg. 1996;21A:451-65. 29. Calandruccio J, Steichen J. Magnetic resonance imaging for diagnosis of digital flexor tendon rupture after primary repair. J Hand Surg. 1995;20B:289-90. 30. Drape J, Hoffman 0, Houvett P, et al. Complication of flexor tendon repair in the hand: MR imaging assessment. Radiology. 1996;198:214-24. 31. LeViet D, Rousselin B, Roulot E, Lantieri L, Godefroy DL. Diagnosis of digital pulley rupture by computed tomography. J Hand Surg. 1996;21A:245-8. 32. Hamman J, Ali A, Phillips C, et al. A biomechanical study
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of the flexor digitorum superficialis: effects of digital pulley excision and loss of the flexor digitorum profundus. J Hand Surg. 1997;22A:328-35. Phillips C, Mass D. Mechanical analysis of the palmar aponeurosis pulley in human cadavers. J Hand Surg. 1996; 21A:240-4. Rispler D, Greenwald D, Shumway S, Allan C, Mass D. Efficiency of the flexor tendon pulley system in human cadaver hands. J Hand Surg. 1996;21A:444-50. Naam NJ. Staged flexor tendon reconstruction using pedicled tendon graft from the flexor digitorum superficialis. J Hand Surg. 1997;22A:323-7. Noguchi M, Seiler JG, Boardman ND, Tramalgini MS, Gelberman RH, Woo L- Y. Tensile properties of canine intrasynovial and extrasynovial flexor tendon autografts. J Hand Surg. 1997;22A:457-63. Ascencio G, Abihaidar G, Leonardi C. Human composite flexor tendon allografts. J Hand Surg. 1996;21B:84-8. Gabuzda GM, Lovallo JL, Nowak MD. Tensile strength of the end-weave flexor tendon repair: an in vitro biomechanical study. J Hand Surg. 1994;19B:397-400. Kleinert HE, Kutz JER, Ashbell JS. Primary repair of lacerated flexor tendons in "no man's land." J Bone Joint Surg. 1967;49A:577. Strickland J, Glogovac Sv. Digital function following flexor tendon repair in zone II: comparison of immobilization and controlled passive motion techniques. J Hand Surg. 1980;5: 537-43. Chow JA, Thames LJ, Dovelle S, Milnor WH, Seyfer AE, Smith AC. A combined regimen of controlled motion following flexor tendon repair in "no man's land." Plast Reconstr Surg. 1987;79:447-53.
Clini cal A ssistant Professor Division of Hand Surgery Department of Orthopaedic Surgery Thomas Jefferson University Philadelphia, Pennsylvania; The Philadelphia Hand Cent er Philadelphia, Penn sylvania
Marc
J. Lamb, MD
The Philadelphia Hand Center Philadelphia, Pennsylvania
estor ation of digital function following R flexor tendon injury continues to challenge the hand surgery and therapy communities. Stiff-
ness and scarring leading to functional impairment continue to frustrate the most experienced surgeons, therapists, and compliant patients. Despite efforts to improve the results of flexor tendon repairs, restrictive adhesions affixing the injured tendon to the flexor tendon sheath continue to compromise functional recovery more than any other problem. Joint contracture and repair rupture present additional obstacles to a successful outcome following repair of flexor tendons. The irreparable tendon and tendon sheath requiring reconstruction remain a troublesome clinical presentation. This paper reviews flexor tendon literature defining today's understanding of the flexor tendon system's response to injury and surgical reconstruction. New techniques will continue to evolve, each having the goal of promoting tendon gliding and limiting postoperative adhesions. As the new millennium approaches, we edge closer to the goal of predictably restoring normal hand function after flexor tendon injury.
This paper is followed, on p . 149, by a paper presenting a hand therapist's commentary on the same subject. Correspondence and reprint requests to John S. Taras, MD, The Philadelphia Hand Center, PC, 834 Chestnut Street, Suite G114, Philadelphia, PA 19107.
ABSTRACT: Medical researcher s continue to exp lore the flexor tendon's response to injury and repair. In recent years, hand surgery and therapy publications have focused on the biomechanics of suture techniques and the benefits of early postoperative motion on su rgically repaired flexor tendons. Lab oratory and clinical studies ha ve sh own that s tronger sutu re techniques can withstand the strain of immediate acti ve m oti on w ithout a significant risk of tendon rupture or gap forma tion . Newl y proposed therapy techniques and anatomic stud ies defining the effects of wrist and digital position on tendon excu rsion share the goals of achieving early motion and reducing restrictive adhesions. Clinical studies have evaluated th e va rious imaging modalities used to diagnose postoperative ad hesions. Other clinical surveys have detailed the use of pedicled autograft and allograft tendons in staged reconstruction. H istologic and immunologic researchers have concentrated on eellular activation patterns followin g tendon injury and the effects of pharmacologic agents, such as hyaluronan and aprotinin, on tendon healing and adhesion formation. J HAND THER 12:141-148, 1999.
HISTOLOGIC AND IMMUNOLOGIC FEATURES OF FLEXOR TENDON INJURY Histologic and immunologic studies have advanced the contemporary understanding of tendon healing and adhesion formation. Using monoclonal antibodies to localize specific inflammatory markers, Khan et al.' have determined that the synovial sheath and epitenon are more reactive than the endotenon in the early period after tendon injury. Using a rabbit model, these authors found that the synovial lining is a dominant factor in the scarring response to injury. Wiig et a1. 2 describe the differences in cellular activities between tendons and synovial sheaths during healing. In a separate study they also describe the effects of hyaluronan on cell proliferation and collagen synthesis.' Wiig et a1. demonstrate in vitro that hyaluronan does not affect the synthesis of matrix components necessary for tendon healing but does inhibit fibroblast proliferation, and a reduction in fibroblasts could reduce adhesion formation. Their subsequent in vivo study, however, reveals that low concentrations of hyaluronan exert no effect on tendon healing or ad hesion formation in a rabbit model. Apparently the hyaluronan gel diffuses too rapidly to have a clinically significant effect in reducing adhesions. A study by Komurcu et a1. 4 attempts to quantify the effect of aprotinin and sheath repair on adhesion formation in lacerated rabbit flexor tendons. April-June 1999
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Utilizing work-of-flexion values to measure adhesion formation, Komurcu et al. find that aprotinin decreases adhesion formation less than primary sheath repair does and much less than sheath repair and aprotinin application combined do. Greenough" finds that pulsed electromagnetic fields induce neither tendon healing nor adhesion formation. Abrahamsson" concludes that longer operative times and wider surgical exposures increase cell proliferation in the rabbit tendon, but irrigation can counteract the negative effects on exposed flexor tendons by preventing tissue desiccation. It is likely that at some time in the future the means will exist to chemically modify the tendon healing environment to limit adhesions and promote healing. The only method proved to decrease adhesion formation thus far is the encouragement of motion between the tendon and its sheath.
ACUTE INJURIES Active Mobilization Recent research indicates that active mobilization after primary tendon repair yields greater and more reliable tendon excursion than passive mobilization. Studies by Kleinert et al.." Strickland and Glogovac," and Chow et al." describe postoperative passive flexion which was usually combined with active extension therapy regimens following flexor tendon repair. These authors describe improved range of motion compared with the historically disappointing results achieved following immobilization, and attribute these findings to enhancement of tendon gliding. Variations of the passive flexion and active extension hand therapy regimen have become the treatment standard following primary flexor tendon repair in compliant patients, yet such protocols have not elicited uniformly favorable recovery of motion. Schenck and Lenhart" employed Chow's active extension and rubberband passive flexion regimen in their series of primary flexor tendon repairs. Their results contrast sharply with Chow's encouraging report, which cites 82% good and excellent results. Schenck and Lenhart report that only a minority (48%) of their patients achieved good or excellent results. The authors state that typical primary flexor tendon repairs may fall far short of reliably restoring normal function. Silfverskiold" evaluated the efficacy of passive flexion and active extension after primary flexor tendon repair. In this study, the author measures tendon excursion during the early mobilization period by tagging tendon repairs with metallic sutures. He concludes that passive flexion techniques can produce tendon excursion approaching that of active flexion, but the variation of excursion among individuals is great. He cautions that not all tendons glide to the same degree after primary repair, and restrictive adhesions are more likely to form in the absence of gliding. Silfverski6ld's study supports the belief that early active flexion should pro142
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duce greater tendon excursion than passive flexion alone.
Biomechanics and Physiology of Tendon Repairs The rationale promoting active mobilization of repaired flexor tendon lacerations developed from the biomechanics and physiology of the healing sutured tendon. A canine study by Urbaniak et al." provides evidence that repaired tendons lose nearly half their initial repair strength within one week of immobilization. After publication of this study, researchers believed the tensile strengths of common repair techniques were insufficient to support active tendon mobilization reliably. To assuage the fear of rupture, surgeons have increased the repair site's ability to withstand the forces transmitted from muscle to bone by devising repair techniques using more suture material. The most common of these applications increase the number of suture strands passed across the repair. A human cadaveric work-of-flexion study by Aoki et al.'? posits a relationship between the quantity of suture used in the repair and the resistance to gliding. According to these authors, the increased resistance to tendon gliding measures 4.8% in the two-strand modified Kessler repair, 6.5% in the lateral margin Becker repair, and 19.3% in the six-strand Savage repair. Bulkier experimental repair techniques-including the :internal tendon splint, external mesh sleeve, and dorsal tendon splint-oppose tendon gliding up to 44% more than the simpler constructs. This study does not consider elements such as tissue swelling and edema; however, work of flexion clearly increases in direct proportion to the amount of suture used to achieve the repair. The work of Kubota et al." elucidates the individual effects of motion and tension on partially transected and repaired chicken flexor tendons. Histologically, the alliance of motion and tension promotes the greatest increase in cellular activity, while the absence of both components generates the least activity. Independently, motion or tension does induce intermediate changes in cellular activity, but less than when the two are combined. Thus, the collaborative efforts of motion and tension appear to enhance the tendon's response to injury. Aoki et al." published a study of the biomechanical and histologic characteristics of canine flexor tendon repairs subject to early active motion. The weaker Kessler repairs rupture in 89% of his specimens; however, none of the Savage or dorsal tendon splint repairs rupture. Most significantly, successful tendon repairs stressed during the healing process appear to lose little initial repair strength when tested for gap formation and tensile strength five days after repair. Aoki et al. note that initial repair strength returns by ten days following repair, and tendons subject to tensile stress in an active-motion postoperative regimen maintain their strength much better than immobilized tendons.
Separate studies presented by Komanduri et al." and Soejima et al." examine core suture placement in cadaveric flexor tendons to determine whether dorsal or volar position influences repair strength. Soejima et al. harvested repaired tendons before stressing them to longitudinal tensile failure. In his survey, dorsally placed suture provides 26.5% greater strength prior to failure than volarly placed suture. Komaduri et al. repaired and tested specimens within their tendon beds, preserving in vivo angulation, loading, and frictional interference. In his curvilinear model, dorsal suture placement proves nearly twice as strong as volar placement. Following reports that epitendinous suture techniques augment repair strength significantly, Diao et al." investigated the depth of placement of running epitendinous suture. His findings indicate that deep suture placement is nearly 80% stronger than superficial placement when used to complement a Kessler core suture. The Diao technique, combining deep epitendinous suture and a Kessler core suture, can tolerate loads up to 40 newtons, but the authors do express concern that this technique may not provide adequate support for an active mobilization program. A study of core suture caliber by Taras et al." indicates that increasing suture gauge significantly augments repair strength. Suture rupture is the cause of failure of the Kessler, Bunnell, and doublegrasping repairs constructed with 4-0 braided polyester in this study. For these two-strand techniques, the core suture strength is independent of technique. As suture gauge increases, however, the technique's grasping characteristics become more significant. Taras et al. report that Kessler repairs pull out of the tendon ends more easily than do Bunnell or double-grasping sutures. In this study, the combination of a 3-0 double-grasping core suture and the cross-stitch epitendinous repair developed by Silverskiold withstands an average ultimate tensile strength of 72 newtons. Theoretic
models indicate that this construct does afford sufficient strength to support an active mobilization protocol. Evans and Thompson" developed a theoretic model determining force application at the repair site. Assuming a posture of 20° wrist extension, 83° metacarpophalangeal (MP) flexion, 75° proximal interphalangeal (PIP) flexion, and 40° dorsal interphalangeal flexion, an external load of 50 g exerts 41 g of tension on the flexor digitorum profundus (FDP) and 605 g of tension on the flexor digitorum superficialis (FDS). Increasing flexion angles to 85° MP (2° increase), 95° PIP (200 increase), and 750 DIP (350 increase) causes a sharp tension increase of 1,650 g on the FDP and 2,050 g on the FDS. Thus, even minimal deviation from the prescribed posture increases the load beyond the repair's tensile capacity. The authors caution against extreme joint positions during active motion rehabilitation exercises when the repair technique might not support these forces.
Clinical Series Recent clinical studies assessing flexor tendon repairs treated with active postoperative protocols and standard passive flexion-active extension protocols demonstrate more good and excellent outcomes than those utilizing passive tendon gliding alone. Baktir et al." prospectively compared the Kleinert rubberband passive flexion-active extension method with an early active mobilization method to treat zone 2 flexor tendon injuries. The percentage of good and excellent results was larger (85% compared to 78%) and the mean grip strength greater (90% versus 84%) in the active mobilization group. Of the 88 repairs cited in this study, two early ruptures occurred in each group. Elliott et al." applied a controlled active motion program to primary repair of flexor tendon lacerations. His repair technique combined a 3-0 or 4-0 Kessler monofilament core suture with a 6-0 run-
FIGURE 1. Left, The cross-stitch epitendinous technique developed by Silfoerskiold. Right, The Taras double-grasping core suture technique. (Reprint ed, with permission, from Taras IS , Skahen IR III, Raphael IS , et al. The double-grasping and crossstitch for acute flexor tendon repair: applications with active motion. In: Schneider LH, Taras IS , eds. Atlas of the Hand Clinics. 1996;1(1):13-28. Copyright 1996, W B Saunders Co.) April-June 1999
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FIGURE 2. The Strickland Indiana method of flexor tendon repair. (Reprinted, with permission, from Schneider LH, Taras IS, eds. Atlas of the Hand Clinics. 1996;1(1):77. Copyright 1996, W B Saunders Co.)
ning epitendinous nylon suture for FDP and flexor pollicis longus (FPL) lacerations. For FDS repairs, he used a 4-0 or 5-0 nylon mattress stitch. With this regimen 5.8% of the fingers and 16.6% of the thumbs had ruptures. Of the 63 fingers with zone 2 lacerations, 79.4% demonstrated good or excellent results. Compared with earlier series reporting passive flexion and active extension regimen results, this study's rupture rate is not appreciably higher in digits other than the thumb. Silfverskiold and May" have offered a new ep)
FIGURE 3. Top, The Sandow modified-Savage single-cross grasp six-strand flexor tenorrhaphy technique prior to knot tying. Bottom, The completed repair. (Reprinted, with permission, from Sandow MI, McMahon MM. Single-cross grasp six-strand repair for acute flexor tenorrhaphy. In: Schneider LH, Taras IS, eds. Atlas of the Hand Clinics. 1996;1(1):4164. Copyright 1996, W B Saunders Co.) 144
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The six-strand loop suture technique for flexor tendon repair, after Lim. (Reprinted, with permission, from Lim BH, Tsai T-M. The six-strand technique for flexor tendon repair. In: Schneider LH, Taras IS, eds. Atlas of the Hand Clinics. 1996; 1(1):65-76. Copyright 1996, W B Saunders Co.)
itendinal suture technique, the cross-stitch, in his study to repair 55 digits with zone 2 flexor tendon lacerations. The cross-stitch creates an external weave resembling a Chinese finger trap (Figure 1, left). The repair technique combines the cross-stitch epitendinal suture with a 4-0 braided Kessler core stitch. The postoperative regimen comprises active extension and passive and active flexion. Two repairs of the 55 (3.6%) ruptured. The mean active DIP and PIP joint motion six months after surgery measured 157° (71% excellent and 25.5% good). These results represent an improvement of 15° motion over results obtained at the same clinic with a passive flexion and active extension regimen. Taras et a1. 21 applied a program of active and passive flexion to 14 digits with flexor tendon laceration repaired using Silfverskiold's cross-stitch combined with a 3-0 braided polyester core suture incorporating an extra grasping throw at each corner of the stitch (Figure 1, right). This series reports an 87% recovery of motion with no ruptures. The therapy protocol starts with place-and-hold exercises on the day following surgery, progresses to active tendon-gliding exercises at three weeks, and initiates resistive exercises by six weeks. The Strickland four-strand suture technique pairs a modified Kessler core stitch of 3-0 braided synthetic suture with a horizontal mattress stitch and a 6-0 nylon epitendinous suture (Figure 2). Thirty-four patients with zone 1 and zone 2 injuries completed an active motion physiotherapy program. Of these patients, nine recovered more than 150° interphalangeal motion, 17 reclaimed 125° to 149° interphalangeal motion, 9 recovered 90° to 124° motion, and 2 recovered less than 90° motion when discharged from therapy. Active interphalangeal motion averaged 130°. Long-term follow-up of 19 digits in this series shows a 19° improvement of interphalangeal joint motion compared with inter-
phalangeal motion when discharged from formal hand therapy. This represents a significant improvement over the same authors' reports of results from a passive flexion and active extension regimen. Sandow and Mclvlahon" and Lim and Tsae3 presented clinical series of different six-strand core suture techniques. Sandow and McMahon modify the Savage technique by placing a single-cross grasp for fixation of each suture limb (Figure 3). They also describe use of a new tendon-holding device that simplifies this technically demanding suture technique. Twenty-three tendons in 18 patients with zone 2 repairs underwent a program of active mobilization. Seventy-eight percent received an excellent or good rating using the Strickland and Glogovac criteria. Mean active interphalangeal motion measured 135°. This series reported no ruptures. Lim and Tsai presented the results of a loop suture technique developed by Tsai to construct a six-strand repair (Figure 4). Thirty-two digits unApril-June 1999
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derwent a rehabilitation regimen employing controlled active and passive motion. One patient suffered a tendon rupture. When graded, 13 (40.5%) achieved more than 132° of active interphalangeal motion, 13 (40.5%) regained 88° to 13r active interphalangeal motion,S (16%) gained 48° to 87" active interphalangeal motion, and excluding the rupture no patients gained less than 47° active interphalangeal motion.
PARTIAL TENDON LACERATION AND RECONSTRUCTION Anatomic studies further defined the structure and dynamic interaction of the flexor tendons and pulley system. Grewal et al. 24 proposed a more accurate method of assessing partial tendon lacerations in zone 2 based on the percentage area of the radial and ulnar bundles of the profundus tendon. This new method factors the cross-sectional area of the profundus tendon and the intratendinous bundles at various levels in zone 2. This formula provides a patient-specific method by which clinicians can assess accurately and easily the size of a partial tendon laceration. Most of the current literature espouses surgical repair using a core suture for tendon lacerations through more than 60% of the flexor tendon. Lacerations of less than 30% do not warrant repair. The recommendation for management of tendon lacerations encompassing 30% to 60% of the tendon is less clear. Flap lacerations that result in triggering or impingement may require repair or debridement, regardless of their size. Preference surveys indicate that the majority of surgeons repair midrange partial lacerations; however, Bishop et a1. 26 and Cooney et a1. 27 report that suturing a partially lacerated tendon can be detrimental to tendon strength.
Diagnosis Adhesions are the most common tendon healing complication. The difficulty distinguishing restrictive adhesions from tendon rupture during the early postoperative period has compelled investigators to seek better methods of visualizing this perplexing clinical situation. Matloub et al.28 surveyed 16 tendons less than eight weeks after repair, each carrying a clinical diagnosis of rupture. In their study, clinical examination yields a 60% accuracy in diagnosis, while magnetic resonance imaging correctly distinguishes adhesions from ruptures in all cases. This study complements prior work by Calandruccio and Steichen" and Drape et a1.,3O who promote magnetic resonance imaging to evaluate adhesion formation, tendon rupture, and gap formation at repair sites. Bare-handed rock climbing has increased in popularity during recent years, and hazards of the sport, including rupture of the pulley system, are more widely encountered today. In this sport one 146
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or two fingers may bear the climber's total body weight. Le Viet et a1.31 reported seven cases of pulley rupture confirmed by computed tomography (CT). In each case, CT scanning visualizes the rupture and establishes a correct diagnosis. For pulley ruptures, CT scanning clearly illustrates the dynamic images of the digits straining against resistance and the resultant bowstringing. Compared with other clinical diagnostics, including standard radiography, ultrasound, and magnetic resonance imaging, CT scanning provides an accurate, easy, and cost-effective imaging procedure to diagnose digital pulley rupture.
The Pulley System Several recent dynamic human cadaveric studies assessed the efficiency of the flexor tendon pulley system.32-34 Evaluating tendon excursion, force, and work, Rispler et al. 34 report that the absence of an A4 pulley results in the largest loss of efficiency of the individually tested pulleys. They report that the loss of a single minor pulley (AI or AS) results in an insignificant loss of efficiency, whereas absence of a major pulley is detrimental to system efficiency as a whole. They report that absence of an A4 causes an 85% loss of work and excursion, and loss of an AZ results in an excursion difference of 94%. A mechanical analysis of the palmar aponeurosis pulley performed by Phillips and Mass" reveals that isolated sectioning of the palmar aponeurosis pulley alone does not significantly change any efficiency parameters. Absence of the palmar aponeurosis and loss of either or both proximal annular pulleys (AI, AZ), however, demonstrates a significant decrease in excursion efficiency. Phillips and Mass stress that the palmar aponeurosis pulley should be considered as important as the annular and cruciate flexor tendon pulleys. Hamman et aP2 examined the effects of digital pulley excision and loss of the profundus tendon on the efficiency of the superficialis tendon using a human cadaver model. They conclude that the A2 and A3 are the most important pulleys for superficialis function, and the profundus is necessary for optimal tendon excursion efficiency.
Tendon Grafts The indications and technique for primary and staged tendon grafting are well established. Infections, adhesions, concurrent neurovascular and osseous injuries, tendon rupture, and patient noncompliance can compromise the result of primary flexor tendon repair. Tendon grafting is the standard procedure for digits when direct repair is not feasible or has failed. The common donor tendons, including the palmaris, plantaris, and toe extensors are extrasynovial grafts. Alternative procedures have recently been introduced to ameliorate clinical situations where standard tendon grafting techniques are not practical.
Naam" reported the use of pedicled flexor digitorum superficialis tendon as a graft in the second stage of reconstruction in 33 digits. On follow-up 3.7 years after surgery, 64% of patients achieved good-to-excellent results, and three of the 33 patients required tenolysis. Patients older than 25 years who had significant soft tissue injuries or who were noncompliant with postoperative therapy demonstrated poorer results. Noguchi et al." explored the benefits of using an intrasynovial autograft such as the superficialis tendon with an adult canine model. They state that intrasynovial tendon grafts exhibit superior gliding function compared with extrasynovial grafts after six weeks of healing. Human composite flexor tendon allografting provides one alternative to salvage a multiple operated digit. Asencio et al." presented two cases followed for five years after composite flexor tendon allografts. Both patients achieved a real functional improvement without any complications; thus, the authors believe that allografting can restore good function without synovitis, infection, or secondary rupture. Issues regarding antigenicity and contagious disease transfer do warrant continued caution regarding the use of allograft tendon. Gabuzda et al." investigated the strength of end-weave repair and assessed the number of weaves on pull-out strength with a human cadaver model. In their survey, they compare the efficacy of the standard mattress suture with a multiple-pass technique doubling the amount of suture material used in the mattress technique. The authors reach two conclusions: First, the results demonstrate a clear relationship between pull-out strength and the number of weaves and suture material used in both methods. Second, the multiple-pass technique imparts stronger pull-out resistance per weave than does the mattress suture. Gabuzda et al. estimate the tensile strength of the multiple-pass end-wave repairs using three, four, or five weaves to be at least 40 to 50 newtons.
CONCLUSION Recent research investigating flexor tendon injuries, surgical repair techniques, and postoperative therapy protocols has refined the results of flexor tendon repair so that satisfactory outcomes can be routinely expected. Future clinical studies will likely show that suture techniques can withstand the forces generated by early active motion therapy protocols. The greater amount of tendon excursion performed with active motion therapy will decrease the significance of restrictive adhesions that currently compromise functional recovery. Basic science advances have enhanced today's understanding of the flexor tendon pulley system's dynamic anatomy. Comprehension of tendon healing will guide future therapy and splinting protocols and may lead to a pharmacologic agent that improves tendon gliding.
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Saunders, 1996:41-64. 23. Lim BH, Tsai T-M. The six-strand technique for flexor tendon repair. In: Taras JS, Schneider LH (eds). Atlas of the Hand Clinic. Philadelphia, Pa.: W B Saunders, 1996:65-77. 24. Grewal R, Sotereanos DG, Rao U, Herndon JH, Woo S1. 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. 1996;21(6):978-83. 25. Strickland JS. The Indiana method of flexor tendon repair. In: Taras JS, Schneider LH (eds). Atlas of the Hand Clinics. Philadelphia, Pa.: W B Saunders, 1996:77-103. 26. Bishop AT, Cooney WP, Wood MB. Treatment of partial flexor tendon lacerations: the effect of tenorrhaphy and early protected mobilization. J Trauma. 1986;26(4):301-12. 27. Cooney WP, Weidman K, Malo D, Wood MB. Management of acute flexor tendon injury in the hand. American Academy of Orthopedic Surgeons Instructional Course Lecture. 1985;34:373-81. 28. Matloub H, Dzwierzynski W, Erikson S, Sanger JR, Yousif NJ, Muoneke V. Magnetic resonance imaging scanning in the diagnosis of zone 2 flexor tendon rupture. J Hand Surg. 1996;21A:451-65. 29. Calandruccio J, Steichen J. Magnetic resonance imaging for diagnosis of digital flexor tendon rupture after primary repair. J Hand Surg. 1995;20B:289-90. 30. Drape J, Hoffman 0, Houvett P, et al. Complication of flexor tendon repair in the hand: MR imaging assessment. Radiology. 1996;198:214-24. 31. LeViet D, Rousselin B, Roulot E, Lantieri L, Godefroy DL. Diagnosis of digital pulley rupture by computed tomography. J Hand Surg. 1996;21A:245-8. 32. Hamman J, Ali A, Phillips C, et al. A biomechanical study
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