The experimental components that influence repair strength are suture material, suture gauge, the number of core strands, suture configuration, suture purchase, and the addition of an epitendinous suture.1 The uniform spread of load through a tendon repair tends to offer the best biomechanical strength and thus the configurations of the Lin modified Kessler and Adelaide repair perform well in ex vivo testing. (See Video, Supplemental Digital Content 4, which displays biomechanical evaluation of six popular tendon repairs. This video is available in the “Related Videos” section of the full-text article on PRSJournal.com or at http://links.lww.com/PRS/B926.) Despite laboratory findings, the clinical evidence to support multistrand repair is less clear.
Several systematic reviews comparing outcomes of two-strand versus multistrand repairs do not support the perceived value of multistrand repairs. The improvements in rupture rates in the past two decades of hand surgery appear to be attributable to improved quality of care and not to an increase in core strands.50 The International Federation of Societies for Surgery of the Hand committee reported a trend for later ruptures with multistrand repairs.51 Early ruptures observed in two strands (average, 18 days) are likely to relate to suture failure, whereas six-strand repairs failed on average 47 days later but are probably related to a disruption of tendon healing. This discrepancy with experimental findings and clinical observations points to other biological factors at play that warrant further research.
In vivo studies have shown that the suture repair of tendon does lead to a gradual weakening of the tendon.52 We have shown that there is a significant and persistent recruitment of inflammatory cells around a sutured tendon and the formation of acellular zones within the grasping component of the repair.53 (See Video, Supplemental Digital Content 5, which displays the effect of suturing tendon. This video is available in the “Related Videos” section of the full-text article on PRSJournal.com or at http://links.lww.com/PRS/B927.) The complex biology of suturing tendon in the context of clinical observations may, in part, explain why ruptures still occur.
It is a matter of debate whether the surgeon’s experience affects outcomes. Moriya et al. found that five of their six ruptures were performed by less experienced surgeons.54 It has been suggested that careful documentation of seniority of the surgeon is required to reflect the competency of the repair.55 Several studies relating to flexor tendon surgery did not find seniority of the surgeon to be a factor in determining outcomes or rupture rates.56,57 However, the simpler the repair, the greater the economy of movement, and less surgical trauma should be the primary repair aspiration.
Division of the flexor digitorum profundus at zone I with the distal stump greater than 1 cm is usually amenable to primary repair (zone 1b and 1c). A short distal stump length (<1 cm in zone 1a) may require tendon repair to or through the bone to ensure adequate repair strength. Many different techniques, which include external fixation, internal fixation with sutures or wires, and bone anchors, have been described (reviewed by Huq et al.58). Where anchorage to the bone is necessary, there are no clinical studies that demonstrate clear superiority of one technique to another. Clinical outcomes of suture anchors are comparable to pullout button techniques but do have a quicker return-to-work time.59
The technical challenges are performing a repair that has sufficient distal and proximal tendon purchase while preserving the A4 pulley and achieving good tendon glide. Often, the window of repair is very small because of the distal interphalangeal joint being flexed, and the repair may impinge on the A4 pulley. This zone Ic/II region historically has been associated with poor outcomes because of repairs impinging on the pulleys or two tendons healing within a narrow sheath space where space is limited and inelastic because of fibro-osseous pulleys. It is also important to realize that within zones I and II, the vincula are prone to injury, and in cases where a tourniquet is used, occult bleeding into the sheath may contribute to adhesion formation (Fig. 5, right). Biomechanical and clinical research has seen perceptions change, from A2 and A4 pulley being critical,60 to seeing any pulley being partially vented in preference of adequate excursion and glide.61 There is Level IV evidence that this is the acceptable practice.62 It is almost impossible to repair a vented pulley without impinging on glide; thus, careful consideration has to be made to which part of the pulley to vent.
In zone II, the decision to repair one or two strands or no strands of flexor digitorum superficialis depends largely on gliding function on the table. We advocate venting enough pulley to allow adequate excursion without resistance. Even slight resistance can give rise to a stuck repair and subsequent rupture, especially at the A4 pulley in the days immediately after surgery. In zones III, IV, and V, tendons move in a more spacious environment without the confines of the fibro-osseous sheath and generally have better outcomes.
Operating in zone III comes with its own challenges, as often injuries to the tendon have associated injuries to the nerves and the palmar arch that require repair (Fig. 5, below). Not infrequently, zone III injuries can result in hidden retracted tendon ends in the carpal tunnel that require exploration and retrieval. In Al-Qattan’s series, 80 percent of zone III tendon injuries required decompression of the carpal tunnel to retrieve tendon ends.63
Zone IV injuries are rare because of protection by the carpal tunnel. Operating in zone V can be a complicated task because of retraction of the tendons into the muscle bellies and the challenge of matching up the correct tendon ends to each other when multiple tendons are divided.64 The close proximity of divided tendons in the zone V region often gives rise to dramatic tendon adhesion. Thus, after repair, early protected active mobilization is critical to maintaining differential glide.65 The aim of any repair performed in any zone would be a strong repair, avoidance of gapping, intraoperative stress testing, appropriate management of the pulleys to ensure glide, and protection of the repair with an appropriate splint that avoids overstressing the repair with active motion.
There remains much controversy on how best to functionally splint the hand following injury, although it is generally accepted that some form of protection is required. Follow-up for hand therapy and splint compliance is often a problem, with one study showing two-thirds of patients removing their splints when they were still at risk of rupture.66
There has been no direct comparison between a Kleinert dynamic traction splint and the newer short splints to clearly identify which is superior, but the simplicity offered by the short splint seems to be attractive to therapists and patients (Fig. 6). The Manchester short splint was introduced to liberate the wrist, increase patient freedom, and improve compliance with splinting.67 The new short splint extends from the dorsal proximal wrist crease to the fingertips. When compared with the traditional dorsal splint, early results at 12 weeks show improved distal interphalangeal joint motion without affecting rupture rates.67
This is now combined with instructions in the safe light use of the hand excluding the injured digit, which helps prevent inappropriate activity and makes the patient aware of how to protect the repair.65 This illustrates the importance of patient education in the safe use of the hand and enhances patient compliance.
The exception to the use of a shorter splint is in less compliant patients, where a traditional long splint with a cage can be used as an alternative. This works especially well in children, who are unable to follow strict instructions to protect the hand, and simultaneously allows sufficient room for unrestricted movement.9,68 In general, children fair better after flexor tendon injury, where good or excellent outcomes can be expected in 80 to 100 percent of patients, whether they have two- or four-core repairs.69–73
Over the years, the change from clinician- to hand therapist–delivered rehabilitation regimens has probably been the single most influential factor on improving results in hand surgery.74 The importance of the dedicated hand therapist, independent of any particular regimen, is essential to achieving any positive outcomes from a tendon repair. To prevent adhesions from forming, it is essential that sufficient “excursion” can be achieved and that, when tendons are in close proximity, they can obtain “differential glide.” It is critical that the repair must move freely through a full range of normal active motion that can then be maintained by one’s favored rehabilitation regimens. Rehabilitation has evolved from passive motion protocols,75 to active extension and passive flexion,76,77 to a combination of these regimens, to early active motion.78 The evolution of these regimens simply relates to active mobilization providing more excursion and differential glide with controlled joint isolation than passive regimens. The move away from the Kleinert dynamic splint to the dorsal blocking splint is attributable largely to simplifying rehabilitation for the patient and its risk of developing flexion contractures in non-compliant patients. A careful balance of active motion78–80 against the tendon repair strength is offered by modern multistrand repairs.81
Two recent meta-analyses generally acknowledge that early active mobilization regimens give better functional outcomes with the trade-off for slightly increased rupture rates.50,82 A randomized controlled study comparing early active mobilization and passive mobilization supports early active mobilization regimens, although universal adoption remains patchy.83
The timing of when best to start rehabilitation remains debatable. Wide-awake local anesthesia without tourniquet surgery commences early active mobilization at the time of surgery and ensures the repair moves freely. Full movement and force should be avoided, as high strain across the repair is unlikely to be helpful for healing.84 Results from in vivo experiments suggest that between 3 and 7 days is the optimal time to commence early active mobilization, when the postoperative swelling has subsided and fibrosis has yet to set in.85 Simple elevation of the operated hand is essential to achieve this.
An 8-year retrospective analysis of 5229 patients revealed a reoperation rate of 6 percent. Of these reoperations, 58 percent constituted tenolysis alone, 38 percent required repeated repair alone, and the remaining 4 percent required tenolysis and repeated repair.8 These cases are relatively rare; thus, evidence for best practice in reoperations is limited. One would expect primary ruptures to fare worse after repeated repair, but reported outcomes suggest that appropriate surgery can achieve acceptable results.86
Tenolysis requires the surgeon to have a good strategy to liberate the tendon from the surrounding scarred tissue, which can often be difficult to assess. Once again, the wide-awake local anesthesia without tourniquet technique is particularly good for this procedure, as it allows one to assess for any mechanical obstacles before closure of the wound. (See Video, Supplemental Digital Content 6, which displays tenolysis and Bunnell A2 pulley reconstruction with the flexor digitorum superficialis under wide-awake anesthesia. This video is available in the “Related Videos” section of the full-text article on PRSJournal.com or at http://links.lww.com/PRS/B928.)
A recent study of 40 patients who underwent tenolysis saw marginal gains from 128 degrees to 192 degrees at 3 months, with a rupture rate of 17.5 percent.87 Strategies to reduce the rupture rate in this cohort would be particularly valuable.
Tendon reconstruction may take the form of a primary graft approach or a more classic two-stage approach using a silicone rod.88 Other methods to reconstruct the flexor tendon include the Paneva-Holevich technique or vascularized tendon transfers (reviewed by Wong et al.89).
In conjunction with these secondary procedures, pulley reconstruction is sometimes required, and many different methods have been described (Fig. 7). Evidence of the superiority of any one method is lacking, but small cases series do report favorable results.90
It is truly remarkable how much experimental and clinical research has been devoted to the area of flexor tendon repair and rehabilitation. Our evolving views of how tendons heal informed by basic science and better clinical data collection are allowing us to develop less invasive and more innovative ways to conduct our flexor tendon management. The levels of evidence in flexor tendon surgery remain poor. Future research should focus on answering key questions with well-designed clinical studies to advance the field. The combination of fundamentals of good surgical approach and meticulous surgery coordinated with up-to-date physiotherapy regimens, patient education, and patient ownership remains the cornerstone of obtaining good outcomes.
The authors thank Alison Roe for help with hand assessment and Andrea Fotticchia for help with the biomechanics video. Richard Wong, B.Sc., Ph.D., and Jason K. F. Wong, M.B.Ch.B., Ph.D., would also like to thank the Medical Research Council for previous and continuing support (G1000788 and MR/M007642/1) on tendon research.
1. Wong JK, Peck F. Improving results of flexor tendon repair and rehabilitation. Plast Reconstr Surg. 2014;134:913e–925e.
2. de Jong JP, Nguyen JT, Sonnema AJ, Nguyen EC, Amadio PC, Moran SL. The incidence of acute traumatic tendon injuries in the hand and wrist: A 10-year population-based study. Clin Orthop Surg. 2014;6:196–202.
3. Tang JB, Amadio P, Guimberteau JC, Chang J. Tang JB, Amadio P, Guimberteau JC, Chang J. Clinical primary flexor tendon repair and rehabilitation. In: Tendon Surgery of the Hand. 2012:Vol. 1, 1st ed. Philadelphia: Elsevier Saunders; 116–170.
4. Gupta A, Gupta AK, Uppal SK, Mittal RK, Garg R, Aggarwal N. Demographic profile of hand injuries in an industrial town of north India: A review of 436 patients. Indian J Surg. 2013;75:454–461.
5. Lees VC, Warwick D, Gillespie P, et al. A multicentre, randomized, double-blind trial of the safety and efficacy of mannose-6-phosphate in patients having zone II flexor tendon repairs. J Hand Surg Eur Vol. 2015;40:682–694.
6. Wiig ME, Dahlin LB, Fridén J, et al. PXL01 in sodium hyaluronate for improvement of hand recovery after flexor tendon repair surgery: Randomized controlled trial. PLoS One 2014;9:e110735.
7. Starnes T, Saunders RJ, Means KR Jr. Clinical outcomes of zone II flexor tendon repair depending on mechanism of injury. J Hand Surg Am. 2012;37:2532–2540.
8. Dy CJ, Daluiski A, Do HT, Hernandez-Soria A, Marx R, Lyman S. The epidemiology of reoperation after flexor tendon repair. J Hand Surg Am. 2012;37:919–924.
9. Cooper L, Khor W, Burr N, Sivakumar B. Flexor tendon repairs in children: Outcomes from a specialist tertiary centre. J Plast Reconstr Aesthet Surg. 2015;68:717–723.
10. Navali AM, Rouhani A. Zone 2 flexor tendon repair in young children: A comparative study of four-strand versus two-strand repair. J Hand Surg Eur Vol. 2008;33:424–429.
11. Jamali AA, Afshar P, Abrams RA, Lieber RL. Skeletal muscle response to tenotomy. Muscle Nerve 2000;23:851–862.
12. Nassab R, Kok K, Constantinides J, Rajaratnam V. The diagnostic accuracy of clinical examination in hand lacerations. Int J Surg. 2007;5:105–108.
13. Dehghani M, Shemshaki H, Eshaghi MA, Teimouri M. Diagnostic accuracy of preoperative clinical examination in upper limb injuries. J Emerg Trauma Shock 2011;4:461–464.
14. McCartney CJ, Brull R, Chan VW, et al. Early but no long-term benefit of regional compared with general anesthesia for ambulatory hand surgery. Anesthesiology 2004;101:461–467.
15. Hadzic A, Arliss J, Kerimoglu B, et al. A comparison of infraclavicular nerve block versus general anesthesia for hand and wrist day-case surgeries. Anesthesiology 2004;101:127–132.
16. Perris TM, Watt JM. The road to success: A review of 1000 axillary brachial plexus blocks. Anaesthesia 2003;58:1220–1224.
17. Lalonde DH. Wide-awake flexor tendon repair. Plast Reconstr Surg. 2009;123:623–625.
18. Lalonde D, Martin A. Tumescent local anesthesia for hand surgery: Improved results, cost effectiveness, and wide-awake patient satisfaction. Arch Plast Surg. 2014;41:312–316.
19. Higgins A, Lalonde DH, Bell M, McKee D, Lalonde JF. Avoiding flexor tendon repair rupture with intraoperative total active movement examination. Plast Reconstr Surg. 2010;126:941–945.
20. Chatterjee A, McCarthy JE, Montagne SA, Leong K, Kerrigan CL. A cost, profit, and efficiency analysis of performing carpal tunnel surgery in the operating room versus the clinic setting in the United States. Ann Plast Surg. 2011;66:245–248.
21. Bismil M, Bismil Q, Harding D, Harris P, Lamyman E, Sansby L. Transition to total one-stop wide-awake hand surgery service-audit: A retrospective review. JRSM Short Rep. 2012;3:23.
22. Leblanc MR, Lalonde J, Lalonde DH. A detailed cost and efficiency analysis of performing carpal tunnel surgery in the main operating room versus the ambulatory setting in Canada. Hand (N Y) 2007;2:173–178.
23. Bruner JM. The zig-zag volar-digital incision for flexor-tendon surgery. Plast Reconstr Surg. 1967;40:571–574.
24. Boyes JH. Incisions in the hand. Am J Orthop. 1962;4:308–311.
25. Dancey A, Titley OG. A modification of the Bruner incision for the hand and review of the literature. J Plast Reconstr Aesthet Surg. 2008;61:1130–1131.
26. Wong J, McGrouther DA. Minimizing trauma over ‘no man’s land’ with flexor tendon retrieval. J Hand Surg Eur Vol. 2014;39:1004–1006.
27. Kleinert H, Kutz JE, Cohen M. Primary repair of zone two flexor tendon lacerations. In: AAOS Symposium on Tendon Surgery in the Hand. 1975:St. Louis: Mosby; 91–104.
28. Pennington DG. Atraumatic retrieval of the proximal end of a severed digital flexor tendon. Plast Reconstr Surg. 1977;60:468–469.
29. Goshgarian GG. Retrieving the proximal end of a severed flexor tendon. Plast Reconstr Surg. 1978;62:108.
30. Sourmelis SG, McGrouther DA. Retrieval of the retracted flexor tendon. J Hand Surg Br. 1987;12:109–111.
31. Sandow MJ. A further tendon retrieval trick. J Hand Surg Br. 1997;22:125–127.
32. Kilgore ES Jr, Adams DR, Newmeyer WL, Graham WP. Atraumatic flexor tendon retrieval. Am J Surg. 1971;122:430–431.
33. Shah SS, Agarwal R, Haywood R. Atraumatic flexor tendon retrieval: The use of a slip knot. J Hand Surg Br. 2006;31:580–581.
34. Kilgore ES Jr, Adams DR, Newmeyer WL, Graham WP. Atraumatic flexor tendon retrieval. Am J Surg. 1971;122:430–431.
35. Wharton EM, Rawlins JM, Stanley PR. Flexor tendon retrieval: Another way. J Hand Surg Eur Vol. 2007;32:518–520.
36. Adeniran A, Babar AZ. A relatively atraumatic method of retrieving retracted digital flexor tendons. J Hand Surg Br. 1997;22:122–124.
37. Ahed K, Moujtahid M, Nechad M. Retrieval of the retracted flexor tendons for long fingers: New tip. Chir Main 2014;33:247–250.
38. Aksu I, Oktem F, Tellioğlu AT. Retrieval of the retracted flexor tendon: A new trick. J Plast Reconstr Aesthet Surg. 2009;62:135–136.
39. Karbalaeikhani A, Yavari M. Flexor tendon retrieval in zone I and II: A new modified technique. Tech Hand Up Extrem Surg. 2012;16:45–47.
40. Measuria HD, McBride TJ, Talwalkar SC. Flexor tendon retrieval: A modified technique. J Hand Surg Eur Vol. 2014;39:671–672.
41. Titley OG. A modification of the catheter method for retrieval of divided flexor tendons. J Hand Surg Br. 1996;21:391–392.
42. Foo TL, Mak DS. Wire loop technique to retrieve flexor tendon. J Hand Surg Am. 2011;36:1115.
43. Iwuagwu FC, Gupta A. A simple tendon retrieval method. J Hand Surg Br. 2004;29:191–193.
44. Kamath BJ, Bhardwaj P. A simple, semirigid, and surgeon-friendly tendon retriever and flexor sheath dilator. J Hand Surg Am. 2007;32:269–273.
45. King IC, Nikkhah D. Re: Wong J. McGrouther D. A. Minimizing trauma over ‘no man’s land’ for flexor tendon retrieval. J Hand Surg Eur. 2014, 39: 1004–6. J Hand Surg Eur Vol. 2015;40:428–430.
46. Li K, Banducci DR, Kahler SH, Hauck RM, Mackay DR, Manders EK. Endoscopic retrieval of severed flexor tendons. J Hand Surg Am. 1995;20:278–279.
47. Morris RJ, Martin DL. The use of skin hooks and hypodermic needles in tendon surgery. J Hand Surg Br. 1993;18:33–34.
48. Thornton DJ, Miller JG. Flexor tendon retrieval: A new twist from a helping hand. J Plast Reconstr Aesthet Surg. 2008;61:1264–1266.
50. Starr HM, Snoddy M, Hammond KE, Seiler JG III. Flexor tendon repair rehabilitation protocols: A systematic review. J Hand Surg Am. 2013;38:1712–7.e1.
52. McDowell CL, Marqueen TJ, Yager D, Owen J, Wayne JS. Characterization of the tensile properties and histologic/biochemical changes in normal chicken tendon at the site of suture insertion. J Hand Surg Am. 2002;27:605–614.
53. Wong JK, Alyouha S, Kadler KE, Ferguson MW, McGrouther DA. The cell biology of suturing tendons. Matrix Biol. 2010;29:525–536.
54. Moriya K, Yoshizu T, Maki Y, Tsubokawa N, Narisawa H, Endo N. Clinical outcomes of early active mobilization following flexor tendon repair using the six-strand technique: Short- and long-term evaluations. J Hand Surg Eur Vol. 2015;40:250–258.
55. Tang JB. Re: Levels of experience of surgeons in clinical studies. J Hand Surg Eur Vol. 2009;34:137–138.
56. Caulfield RH, Maleki-Tabrizi A, Patel H, Coldham F, Mee S, Nanchahal J. Comparison of zones 1 to 4 flexor tendon repairs using absorbable and unabsorbable four-strand core sutures. J Hand Surg Eur Vol. 2008;33:412–417.
57. Frueh FS, Kunz VS, Gravestock IJ, et al. Primary flexor tendon repair in zones 1 and 2: Early passive mobilization versus controlled active motion. J Hand Surg Am. 2014;39:1344–1350.
58. Huq S, George S, Boyce DE. Zone 1 flexor tendon injuries: A review of the current treatment options for acute injuries. J Plast Reconstr Aesthet Surg. 2013;66:1023–1031.
59. McCallister WV, Ambrose HC, Katolik LI, Trumble TE. Comparison of pullout button versus suture anchor for zone I flexor tendon repair. J Hand Surg Am. 2006;31:246–251.
60. Peterson WW, Manske PR, Bollinger BA, Lesker PA, McCarthy JA. Effect of pulley excision on flexor tendon biomechanics. J Orthop Res. 1986;4:96–101.
61. Tang JB. Release of the A4 pulley to facilitate zone II flexor tendon repair. J Hand Surg Am. 2014;39:2300–2307.
62. Kwai Ben I, Elliot D. “Venting” or partial lateral release of the A2 and A4 pulleys after repair of zone 2 flexor tendon injuries. J Hand Surg Br. 1998;23:649–654.
63. Al-Qattan MM. Flexor tendon repair in zone III. J Hand Surg Eur Vol. 2011;36:48–52.
64. Mehdi Nasab SA, Sarrafan N, Saeidian SR, Emami H. Functional outcome of flexor tendon repair of the hand at zone 5 and post operative early mobilization of the fingers. Pak J Med Sci. 2013;29:43–46.
65. Wilhelmi BJ, Kang RH, Wages DJ, Lee WP, May JW Jr. Optimizing independent finger flexion with zone V flexor repairs using the Massachusetts General Hospital flexor tenorrhaphy and early protected active motion. J Hand Surg Am. 2005;30:230–236.
66. Sandford F, Barlow N, Lewis J. A study to examine patient adherence to wearing 24-hour forearm thermoplastic splints after tendon repairs. J Hand Ther. 2008;21:44–52; quiz 53.
67. Peck FH, Roe AE, Ng CY, Duff C, McGrouther DA, Lees VC. The Manchester short splint: A change to splinting practice in the rehabilitation of zone II flexor tendon repairs. Hand Ther. 2014;19:47–53.
68. Ashall G, Foster A. The “cage” splint: An added protection for flexor tendon repair. J Hand Surg Br. 1989;14:128.
69. Grobbelaar AO, Hudson DA. Flexor tendon injuries in children. J Hand Surg Br. 1994;19:696–698.
70. Kato H, Minami A, Suenaga N, Iwasaki N, Kimura T. Long-term results after primary repairs of zone 2 flexor tendon lacerations in children younger than age 6 years. J Pediatr Orthop. 2002;22:732–735.
71. Navali AM, Rouhani A. Zone 2 flexor tendon repair in young children: A comparative study of four-strand versus two-strand repair. J Hand Surg Eur Vol. 2008;33:424–429.
72. O’Connell SJ, Moore MM, Strickland JW, Frazier GT, Dell PC. Results of zone I and zone II flexor tendon repairs in children. J Hand Surg Am. 1994;19:48–52.
73. Nietosvaara Y, Lindfors NC, Palmu S, Rautakorpi S, Ristaniemi N. Flexor tendon injuries in pediatric patients. J Hand Surg Am. 2007;32:1549–1557.
74. Peck FH, Kennedy SM, Watson JS, Lees VC. An evaluation of the influence of practitioner-led hand clinics on rupture rates following primary tendon repair in the hand. Br J Plast Surg. 2004;57:45–49.
75. Duran RJ, Houser RG, Coleman CR, Postlewaite DS. A preliminary report in the use of controlled passive motion following flexor tendon repair in zones II and III. J Hand Surg. 1976;1:79.
76. Lister GD, Kleinert HE, Kutz JE, Atasoy E. Primary flexor tendon repair followed by immediate controlled mobilization. J Hand Surg Am. 1977;2:441–451.
77. Kleinert HE, Kutz JE, Atasoy E, Stormo A. Primary repair of flexor tendons. Orthop Clin North Am. 1973;4:865–876.
78. Small JO, Brennen MD, Colville J. Early active mobilisation following flexor tendon repair in zone 2. J Hand Surg Br. 1989;14:383–391.
79. Iwuagwu FC, McGrouther DA. Early cellular response in tendon injury: The effect of loading. Plast Reconstr Surg. 1998;102:2064–2071.
80. Kubota H, Manske PR, Aoki M, Pruitt DL, Larson BJ. Effect of motion and tension on injured flexor tendons in chickens. J Hand Surg Am. 1996;21:456–463.
81. Wu YF, Tang JB. Recent developments in flexor tendon repair techniques and factors influencing strength of the tendon repair. J Hand Surg Eur Vol. 2014;39:6–19.
82. Chesney A, Chauhan A, Kattan A, Farrokhyar F, Thoma A. Systematic review of flexor tendon rehabilitation protocols in zone II of the hand. Plast Reconstr Surg. 2011;127:1583–1592.
83. Trumble TE, Vedder NB, Seiler JG III, Hanel DP, Diao E, Pettrone S. Zone-II flexor tendon repair: A randomized prospective trial of active place-and-hold therapy compared with passive motion therapy. J Bone Joint Surg Am. 2010;92:1381–1389.
84. Rawson SD, Margetts L, Wong JK, Cartmell SH. Sutured tendon repair; a multi-scale finite element model. Biomech Model Mechanobiol. 2015;14:123–133.
85. Cao Y, Chen CH, Wu YF, Xu XF, Xie RG, Tang JB. Digital oedema, adhesion formation and resistance to digital motion after primary flexor tendon repair. J Hand Surg Eur Vol. 2008;33:745–752.
86. Dowd MB, Figus A, Harris SB, Southgate CM, Foster AJ, Elliot D. The results of immediate re-repair of zone 1 and 2 primary flexor tendon repairs which rupture. J Hand Surg Br. 2006;31:507–513.
87. Breton A, Jager T, Dap F, Dautel G. Effectiveness of flexor tenolysis in zone II: A retrospective series of 40 patients at 3 months postoperatively. Chir Main 2015;34:126–133.
88. Hunter JM. Staged flexor tendon reconstruction. J Hand Surg Am. 1983;8:789–793.
89. Wong R, Alam N, McGrouther AD, Wong JK. Tendon grafts: Their natural history, biology and future development. J Hand Surg Eur Vol. 2015;40:669–681.
90. Bunata RE. Primary pulley enlargement in zone 2 by incision and repair with an extensor retinaculum graft. J Hand Surg Am. 2010;35:785–790.