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This case is of a zone 2 flexor tendon repair for flexor tendon injury in a little finger. The attending surgeon presents a repair with a 4-0 Ethibond suture with a modified Kessler stitch which resulted in an 8-core strand repair. The procedure was done under wide awake local anesthesia no tourniquet (WALANT) protocol, which among other strengths allows the surgeon to test the repair and set postrehabilitation expectations for the patient. The procedure starts with a Brunner incision and is closed with 5-0 chromic suture in a horizontal mattress fashion. After closure, a dorsal extension block plaster splint was applied. The indication for this surgery was to restore little finger flexion at the distal interphalangeal (DIP) joint. Finger flexor tendons include the flexor digitorum superficialis (FDS) and flexor digitorum profundis (FDP). Common causes of zone 2 flexor tendon injuries include superficial and deep lacerations to the volar aspect of the hand, crush injuries, and saw blade cuts. Early surgical repair is the definitive treatment for greater than 60% rupture of tendon. Postoperatively, patients undergo active extension – passive flexion to achieve functional gliding of the tendon. Patients can expect to return to light activities after 6–8 weeks and resume heavy activities around 10–12 weeks.
Flexor tendon injuries include trauma to the flexor digitorum superficialis (FDS), flexor digitorum profundis (FDP), or flexor pollicis longus (FPL) tendons. Injuries to these tendons are considered rare, with an incidence of 4.83 per 100,000 persons in 2018.1 Flexor tendon injuries are primarily described by injury location first outlined by Kleinert and Verdan in five specific zones.1, 2
Zone 1: Region from FDS insertion to the FDP tendon.
Zone 2: The proximal aspect of the A1 pulley to the FDS insertion.
Zone 3: Distal transverse aspect of the carpal ligament to the A1 pulley.
Zone 4: The carpal tunnel.
Zone 5: Proximal border of the transverse carpal ligament to the musculotendinous junction in the proximal forearm.
Flexor tendon injuries frequently lead to the inability to flex the fingers in the hand, necessitating a surgical repair, preferably within ten days of injury.3
Patients often present with a loss of active flexion of the distal interphalangeal (DIP) or proximal interphalangeal (PIP) joint in the involved digit with complete tears. Knowing the mechanism or injury (clean or dirty knife) can help make decisions that impact peri and postoperative care.4
Patient’s right little finger rests in extension. This patient presents with an altered cascade and an inability to flex DIP with intact PIP flexion. Passive ROM intact. A 2-cm laceration present at volar base of the metacarpophalangeal (MCP) joint that was closed with suture. Neurovascularly intact in all fingers and the hand and wrist.
Radiographs may be obtained to rule out an associated fracture. An ultrasound may be used to assess suspected lacerations.
Without prompt surgical intervention to repair a flexor tendon rupture, healing by primary tendon repair may no longer be possible due to proximal tendon end swelling, tendon contraction, and muscle fibrosis. If no intervention is performed, the patient can experience a decrease in finger flexion strength and ROM due to the development of scar tissue and retraction of the tendon proximally.5 This is especially true with zone 2 injuries where the presence of multiple pulleys and intervening tendons impair the free motion of the tendon.6
Treatment options vary significantly when addressing partial versus complete tendon ruptures. A survey completed in 1995 found that 75% of surveyed hand surgeons would repair partial tendon lacerations greater than 50% of the tendon.7 More recent studies show that cutoff has risen to 60%.4 However, the standard of care for complete tendon rupture—as in this case—is surgical repair. The timeline for repair is debated; however, there is a consensus that the sooner the repair, the better the outcome. Postoperative rehabilitation includes active extension – passive flexion to achieve function and gliding, while avoiding rupture of the tendons.8
There exists a multitude of techniques for surgeons to repair the tendon; however, tendon repair is a companion of core and peripheral sutures, both contributing to the strength of the repair. Studies have shown that strength of tendon repair is proportional to the number of sutures that cross the repair site.9, 10 The choice of suture material for tendon repair is highly variable and dependent on the surgeon’s preference and individual experience.11 Recent studies are also shedding light on the concept that in the setting of a strong core suture, a lack of peripheral sutures produced no postsurgical rupture of the tendon repair.12
Surgical tendon repair was done in this case to establish flexor function across the DIP joint. Repair was accomplished with a 4-0 Ethibond suture with a modified Kessler stitch which resulted in a 2-core strand repair. Ideally a 4- or 6-stand repair is used; therefore, additional sutures are placed to augment the repair site resulting in an 8-core strand repair with an epitendinous stitch placed as well.
Primary repair of the tendon is contraindicated in cases of severe multiple tissue injuries to the fingers, when the wounds are dirty or contaminated, or when there has been skin loss overlying the flexor system.13
This case presents a zone 2 tendon injury repair involving the reattachment of the FDP tendon after a complete rupture. Outcomes for tendon injury repair vary significantly based on the mechanism of injury. Outcomes are worse with concomitant fractures, nerve injuries, contaminated wounds, crush injuries, and injuries that occur with tearing mechanisms such as a saw or lathe.13-16 Patients can expect to return to light activities after 6–8 weeks and resume heavy activities around 10–12 weeks. Successful rehabilitation includes active extension – passive flexion exercises to promote strong and successful healing. Early rehabilitation can start at 3 days post-op if adequate repair was able to be performed.
Typical surgical time for this procedure is around 30–60 minutes, and it can be performed under sedation or wide awake with local anesthetic (WALANT). Benefits of the WALANT technique include increased safety and convenience, decreased cost, the ability to test strength and complications of repair, and to show the patient the expected functional goals with proper postoperative rehabilitation. Complications of tendon repair include adhesion formation, joint contractures, tendon rerupture, triggering, bowstringing, quadriga, and other common complications after surgical interventions.17 Risk of complications are lowered with proper surgical technique and rehabilitation course.
The best technique for use in zone 2 tendon repairs remains unclear to date. There exists significant variation among the type of sutures, the number of strands, use of core and peripheral strands, and the type of suture stitching technique. Due to force restraints of the need for early active motion of the finger, it is generally believed that a four-strand core suture (with a 4-0 or 3-0 non-absorbable suture) is a minimum requirement.18 Many surgeons use six, eight, or more stranded sutures for increased strength of repair. Care should be taken to avoid bulky and twisted sutures, which can interfere with smooth gliding of the tendon. Tang (2013) outlined that partial venting of the A2 pulley can be effective in allowing greater degree of tendon motion if the other annular pulleys are intact and release is less than 2 cm.18 One notable change in outcomes is the decrease in rate of rupture for zone 2 flexor tendon repairs. A review of the rates of rupture ranges from 0–5% over the past decade and a half.18 Further research is currently being conducted as to the optimal use of all these factors based on clinical in vivo human studies.
No special equipment is needed.
Nothing to disclose.
The patient referred to in this video article has given their informed consent to be filmed and is aware that information and images will be published online.
The authors would like to thank the operating room staff for their help in making this video.
- Klifto CS, Capo JT, Sapienza A, Yang SS, Paksima N. Flexor tendon injuries. J Am Acad Orthop Surg. 2018;26(2):e26-e35. doi:10.5435/JAAOS-D-16-00316.
- Wolfe SW, Pederson WC, Hotchkiss RN, Kozin SH, Cohen MS. Green’s Operative Hand Surgery. 6th ed. Elsevier; 2011.
- Brotzman SB, Novotny SR. Clinical Orthopaedic Rehabilitation: a Team Approach. 4th ed. Elsevier; 2018.
- Griffin M, Hindocha S, Jordan D, Saleh M, Khan W. An overview of the management of flexor tendon injuries. Open Orthop J. 2012;6:28-35. doi:10.2174/1874325001206010028.
- Ruchelsman DE, Christoforou D, Wasserman B, Lee SK, Rettig ME. Avulsion injuries of the flexor digitorum profundus tendon. J Am Acad Orthop Surg. 2011;19(3):152-162. doi:10.5435/00124635-201103000-00004.
- Kotwal PP, Ansari MT. Zone 2 flexor tendon injuries: venturing into the no man's land. Indian J Orthop. 2012;46(6):608-615. doi:10.4103/0019-5413.104183.
- McCarthy DM, Boardman ND III, Tramaglini DM, Sotereanos DG, Herndon JH. Clinical management of partially lacerated digital flexor tendons: a survey [corrected] of hand surgeons. J Hand Surg Am. 1995;20:273-275. doi:10.1016/s0363-5023(05)80023-1.
- Boyer MI, Strickland JW, Engles DR, Sachar K, Leversedge FJ. Flexor tendon repair and rehabilitation: state of the art in 2002. J Bone Joint Surg Am. 2002;84(9):1684-706.
- Barrie KA, Tomak SL, Cholewicki J, Wolfe SW. The role of multiple strands and locking sutures on gap formation of flexor tendon repairs during cyclical loading. J Hand Surg Am. 2000;25:714-20. doi:10.1053/jhsu.2000.9414.
- Sanders DW, Milne AD, Johnson JA, Dunning CE, Richards RS, King GJ. The effect of flexor tendon repair bulk on tendon gliding during simulated active motion: an in vitro comparison of two-strand and six-strand techniques. J Hand Surg Am. 2001;26:833-40. doi:10.1053/jhsu.2001.24959.
- Wu YF, Tang JB. Recent developments in flexor tendon repair techniques and factors influencing strength of the tendon repair. J Hand Surg Eur. 2014 Jan;39(1):6-19. doi:10.1177/1753193413492914.
- Giesen T, Sirotakova M, Copsey AJ, Elliot D. Flexor pollicis longus primary repair: further experience with the tang technique and controlled active mobilization. J Hand Surg Eur. 2009;34:758-61. doi:10.1177/1753193408096025.
- Strickland JW. Flexor tendon repair. Hand Clin. 1985 Feb;1(1):55-68.
- 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 Dec 1;37(12):2532-40. doi:10.1016/j.jhsa.2012.09.021.
- Bell Krotoski JA. Flexor tendon and peripheral nerve repair. Hand Surg. 2002 Jul;7(1):83-100. doi:10.1142/s021881040200087x.
- Kleinert HE, Kutz JE, Atasoy E, Stormo A. Primary repair of flexor tendons. Orthop Clin North Am. 1973 Oct 1;4(4):865-76.
- Lilly SI, Messer TM. Complications After Treatment of Flexor Tendon Injuries. J Am Acad Orthop Surg. 2006 July;14(7):387-396. doi:10.5435/00124635-200607000-00001.
- Tang JB. New developments are improving flexor tendon repair. Plast Reconstr Surg. 2018 June;141(6):1427-37. doi:10.1097/PRS.0000000000004416.
Cite this articleChaim Miller, Asif M. Ilyas, MD, FACS. Flexor tendon repair for a zone 2 fdp tendon laceration. J Med Insight. 2022;2022(329). https://doi.org/10.24296/jomi/329
Table of Contents
- Injection of Local Anesthesia
- Mark Incision
- Examination of Tendon Sheath and Digital Nerves
- Retrieval of Proximal FDP Tendon Stump
- Retrieval of Distal FDP Tendon Stump
- Pass Proximal Stump Through Pulley
- Approximation of Tendon Ends
- Testing of Core Sutures
- Post-op Remarks
This is a case of a zone 2 flexor tendon laceration of the right small finger. The patient experienced this laceration with a kitchen knife. He presented to the office with an altered cascade and inability to fully flex his small finger as can be seen here. PIP motion is intact, but DIP motion is lacking, indicating likely FDP tendon laceration. The procedure is being performed in an operating room using a traditional WALANT technique. The patient is awake and alert. He has already been injected preoperatively in the holding area with 9 cc of 1% lidocaine mixed with 1 cc of bicarbonate.
5 cc were injected at the level of the A1 pulley, 2 cc over the proximal phalanx, another 2 cc over the middle phalanx, and 1 cc over the pulp. Those sites are being re-injected here just to make sure that we have a good block and to augment the initial injection.
The laceration site is already marked. Now the skin incision is being marked by incorporating the laceration using Bruner incisions. Alternatively, a mid-axial incision could also be utilized as readily.
Once anesthetized and marked out, the incisions are placed. It's worth noting for a moment why the WALANT technique is being utilized here. Obviously, WALANT provides a number of advantages including safety, convenience, and decreased cost. But in the setting of a flexor tendon repair procedure, there's also the significant advantage of being able to test one's repair to make sure that adequate repair strength has been achieved, that there's no catching or triggering or bunching of the repair site over any of the pulleys, to make sure full composite flexion is achieved, and to show the patient what they can achieve postoperatively with rehabilitation. This is a significant advantage over traditional techniques where the patient is asleep where the repair cannot be challenged intraoperatively.
Once the incisions have been placed, tenotomy scissors are then used to elevate the flaps. Skin hooks are then used to retract the flaps. Once elevated, the flaps can be tagged with silk sutures to help mobilize them and aid in exposure during the case.
With the flexor sheath fully exposed, the sheath is examined and also the digital nerves are examined. Anytime you have a flexor tendon injury, there's a high likelihood of an associated digital nerve injury as well. In this case, both nerves were confirmed to be intact based on direct visualization. Next, the flexor tendons are examined in the sheath. Here, the laceration in the sheath is quite evident, and an intact FDS, or flexor digitorum sublimis, tendon is confirmed, but no FDP, or flexor digitorum profundus, tendon is present.
Therefore, the proximal end of the FDP tendon is sought. Oftentimes it is retracted to the level of the A1 pulley. Here, the A1 pulley is being exposed, and a small opening in the sheath over the A1 pulley is placed in order to retrieve the FDP tendon. Once retrieved, the proximal FDP tendon stump is tagged with the suture. Here, I'm using a 4-0 Ethibond, which is a non-absorbable, braided suture, using a standard modified Kessler technique as shown here. There are a number of ways to repair flexor tendons, and this is one of just many of those techniques. Careful atraumatic tendon handling should be implemented throughout. Here, you'll see that I'm holding the tendon only one time with my Adson's pickup, centrally. I'm avoiding multiple times of grabbing and letting go of the tendon. I'm also trying to minimize the number of times my suture has to run through the tendon. All of these things will aid in hopefully minimizing scarring and adhesions at the repair site.
Next, as was done proximally, the distal stump of the FDP tendon is identified. In this case, the tendon is sitting at the level of the A4 pulley. That pulley is partially taken down in order to expose the tendon for tagging with the similar suture as proximally. Again, atraumatic technique is being emphasized during suture placement in the distal tendon stump as was done proximally. And again, a modified Kessler stitch is also being placed distally as was placed proximally as well. It should also be noted that the pulleys are preserved whenever possible. In this case, a limited opening in the A1 and A4 pulleys were made, but the A2 pulley was completely preserved.
Once tagged, the proximal stump is then brought distally by running it through the remaining pulleys as shown here and making sure that the orientation of the tendon is appropriate relative to the intact FDS tendon. Here, the proximal tendon can be confirmed delivered into the repair site. It is under the FDS tendon proximally, through the chiasm, and now sitting at the level of the laceration site for repair.
The needle is placed through the tendon and the pulley proximally to hold the tendon in position, and the repair is undertaken with the assistant sitting across as shown here. Care must be taken to put the sutures down without excessive tension or bunching. The goal is just for the tendon ends to touch. All of these results in a 2-core strand suture repair. Ideally a minimum of 4, if not up to 6- to 8-core strand repair is preferable. Therefore, additional sutures are placed in either a box stitch or a modified Kessler technique to help augment the repair site as shown here. In this case, an 8-strand core suture repair was ultimately achieved and then reinforced with an epitendinous repair.
However, prior to the epitendinous repair of the suture, the core suture repair is tested with active motion by the patient. Here, the needle in the tendon is removed. The hand is freed. And the patient is asked to actively flex all his fingers, including his small finger to confirm that composite flexion is achieved. And there's no catching or triggering of the tendon in any plane as confirmed here. Again, the patient is awake and therefore able to do this actively. In addition, I typically will show the patient their ability to actively flex the finger as demonstrated here so they can also appreciate that the tendon has been repaired.
[Background] Let's do it. Do me a favor. Roughly make a fist. Keep going, going, going, going, going - relax. Wiggle both your fingers as best you can. Good, now make a fist again. Good, and relax, good. I'm going to just gently… I'll show you as well, so just take all this, all right?
Once satisfied with the repair strength of the core sutures and the excursion achieved, the final repair sutures are placed. In this case, the epitendinous repair is being achieved with a 6-0 monofilament suture in a running fashion circumferentially around the repair site. This helps minimize the bunching of the repair site while also increasing the strength at the repair site. The epitendinous repair is placed in a running, baseball-stitch fashion or locking-stitch fashion circumferentially, starting from the superficial side running deep and then repairing back to itself at the end.
Once satisfied, the wound is washed and closure is initiated. Any various skin closure techniques can be utilized. I typically utilize a 5-0 chromic suture closure in a simple or a horizontal mattress fashion as demonstrated here.
And here is the wound closed. Once closed, a dorsal extension block splint is applied with plaster in the operating room. Here, you can see the wound is dressed sterilely and then covered in Webril prior to application of the plaster.
The splint will be utilized until the patient begins formal hand therapy under the supervision of a hand therapist. At that point, the plaster dorsal extension block splint can be changed to a removable version either with plaster or OrthoBlast, and flexor tendon rehab per protocol will be undertaken utilizing either a modified Duran protocol or an early active motion protocol. The first 6 weeks of both protocols involves protecting the repair site with a dorsal extension block splint for the first 4 to 6 weeks prior to advancing to full composite flexion and extension. Strengthening typically is initiated at 6 to 8 weeks postoperatively. Thank you.