Zone 1 flexor tendon injuries: A review of the current treatment options for acute injuries

Zone 1 flexor tendon injuries: A review of the current treatment options for acute injuries

Journal of Plastic, Reconstructive & Aesthetic Surgery (2013) 66, 1023e1031 REVIEW Zone 1 flexor tendon injuries: A review of the current treatment ...

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Journal of Plastic, Reconstructive & Aesthetic Surgery (2013) 66, 1023e1031

REVIEW

Zone 1 flexor tendon injuries: A review of the current treatment options for acute injuries S. Huq*, S. George, D.E. Boyce Welsh Centre for Burns and Plastic Surgery, Morriston Hospital, Hoel Maes Eglwys, Morriston, Swansea, Wales SA6 6NL, United Kingdom Received 28 January 2013; accepted 6 April 2013

KEYWORDS Flexor tendon; Profundus; Avulsion; Repair techniques

Summary Zone 1 flexor tendon avulsion and laceration injuries are commonly managed by plastic surgeons. These injuries are traditionally repaired using the button pullout technique originally described by Bunnell in 1940. The morbidity related to this method is well documented and this has lead to the development of alternative repair methods. These include modifications of the pullout button technique, internal suture techniques and more recently techniques using bone anchors. However, at present no one technique has been shown to be superior to the others either in terms of outcome or low complication rates. This review examines the published techniques for dealing with these injuries with a view to providing the reader with the available outcome data for each repair type. ª 2013 British Association of Plastic, Reconstructive and Aesthetic Surgeons. Published by Elsevier Ltd. All rights reserved.

Anatomy and classification Zone 1 flexor tendon injuries affect the flexor digitorum profundus tendon (FDP) distal to the insertion of the superficialis tendon. They are a relatively common condition and occur predominantly in young adults. The mechanisms of injury are usually lacerations or closed avulsions, with the latter occurring as a result of a forced extension to the distal phalanx of a finger that is actively flexing.1 The * Corresponding author. E-mail address: [email protected] (S. Huq).

degree to which the proximal tendon retracts determines the classification and this in turn influences the management options. Other key factors include the presence of an associated distal phalanx fracture, the delay to treatment and the vascularity of the tendon.2,3 The avulsion injuries occur most commonly in the ring finger and a number of theories have been postulated to explain this. In a cadaveric study, Manske and Lester demonstrated the insertion of the ring FDP was significantly weaker than that of the middle finger.4 Bynum and Gilbert showed the ring finger was the most prominent digit during flexion and thus experienced the most force during pull-away testing.5

1748-6815/$ - see front matter ª 2013 British Association of Plastic, Reconstructive and Aesthetic Surgeons. Published by Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.bjps.2013.04.026

1024 The most widely used classification system for describing avulsion injuries is that of Leddy and Packer, which has been modified to incorporate specific injury subtypes.6 In type 1 injuries the proximal stump of the FDP retracts into the palm resulting in partial devascularisation of the tendon. The collapsed sheath fills with haematoma leading fibrosis and the muscle belly is prone to developing a myostatic contracture preventing tendon stump advancement1 (Figure 1). In type 2 avulsions the tendon retracts to the level of the proximal interphalangeal joint (PIPJ) with or without a small avulsion fracture. These are the most common type of avulsion injuries and repair can be attempted up to three months after the injury with good results.7e9 Type 3 injuries are characterized by a large bony avulsion fragment that prevents the tendon retracting beyond the distal edge of the A4 pulley.10 In type 4 injuries there is a simultaneous avulsion fracture along with an associated avulsion of the tendon from the bony fragment.11 Type 5 injuries are characterised by a distal phalanx fracture along with avulsion of the FDP.12 Moimen and Elliot have classified laceration injuries of zone 1 into 3 distinct subgroups. Group 1a represent lacerations distal to the A5 pulley where it is impossible to place a core suture. Zone 1b represent injuries between the distal edge of the A4 pulley and zone 1a. Lastly, those injuries beneath the A4 pulley are classes as zone1c.13 Thus, zones 1b and c can be repaired using conventional tendon repair techniques, whereas zone 1a is treated in the same manner as the avulsion injuries.7,14 Furthermore as with the avulsion injuries the management of the lacerated FDP can be complicated by an associated distal phalangeal fracture.

Treatment options The treatment of these injuries is challenging and the outcomes so far have not been as satisfactory as those of

S. Huq et al. other tendon injuries. In a recent paper by Moiemen et al. only 50% of patients achieved good or excellent outcomes following repair.13,15 The decision on whether to operate needs to take into account the chronicity of the injury, the size of the bone fragment, the type of avulsion and associated injures. Fortunately, in the majority of cases a direct repair can be attempted using a variety of techniques described in the literature. The ideal repair should be able to withstand the stresses encountered during the rehabilitation phase and leave the digit free from flexion contracture. At present, no one technique has been shown to be superior to the others in terms of outcome and complication rates. The aim of this review is to focus on the published techniques for dealing with Types 1 and 2 distal FDP injuries which form the majority of cases with a view to providing the reader with the available outcome data for each repair type. In cases where the tendon cannot be retrieved or there is greater than 1 cm tendon loss there are a number of treatment options. The patient can be offered joint fusion as an immediate or delayed procedure if the distal interphalangeal joint (DIPJ) becomes unstable. If the pulley system is intact there is the option of primary tendon graft or in the case of pulley disruption a two-stage reconstruction addressing both the tendon and pulley system.1,8 These injuries are difficult to treat and a comprehensive discussion with the patient on rehabilitation and likely outcomes should precede any treatment. Patients with zone 1 flexor tendon injuries can be treated using either internal or external fixation techniques. The external button pullout technique originally described by Bunnell in 1940 is still widely used.1 However, there has been an increasing trend in the literature towards internal fixation in order to avoid some of the complications associated with the external button technique. The various repair techniques are illustrated in Figures 2e4 with the outcomes summarized in Table 1.

External fixation techniques

Figure 1 Classification of zone 1 flexor digitorum profundus avulsion injuries.

The original Bunnell technique used a stainless steel suture that was tied over a thicker piece of wire externally. This was modified by Littler where the steel suture was tied over a button placed over the nail plate. Further modifications include replacing the steel suture with monofilament sutures and using different suture configurations.1,16 Since the suture is externalized and must be removed, these techniques rely on non-locking suture techniques (e.g. Bunnell or Kessler) that are biomechanically weaker compared to locking sutures and this is one disadvantage of the pullout technique.17,18 The suture type also plays a role in the strength of the repair with ethibond being shown to have significantly greater pullout strength (44.9 N vs 37.6 N) and less gapping (1.7 mm vs 6.8 mm) compared to the monofilament prolene sutures.19 Furthermore, Silva et al. attributed some of the gapping seen with the pullout technique to the increased length of suture between the tendon stump and the point of fixation externally.20 This phenomenon may in part explain why the outcomes in zone 1 repairs are often suboptimal, with some studies reporting good outcomes in only 50% of patients (Figure 2).13

Zone 1 flexor tendon injuries

1025

Figure 2

External fixation techniques.

The button pullout technique is associated with a number of well documented complications. Kang et al. has reported an infection rate of 22% and abnormal nail growth occurring in 35% of patients.18 The button can catch on clothing and can make hand hygiene difficult. Patients can experience pain from the button pressing down on the nail and if placed to proximally, necrosis of the nailfold skin can occur. This has prompted a search for alternative and better repair techniques. Mantero et al. in 1973 described a pullout technique that placed the button at the tip of the finger, thus avoiding placing pressure on the specialized nailbed tissues.21 The FDP stump is retrieved and sutured using a 2-0 or 30 monofilament suture using the Kirchmayer technique, with the distal ends passed through the tendon stump and then to the fingertip. The repair is re-enforced using a 6.0 epitendinous suture and thus is only suitable for distal lacerations and not avulsions. Using this technique, Schaller al. demonstrated good/excellent results in 54% of patients using Strickland’s criteria, with this decreasing to only 38% when assessing DIPJ motion only.15 Montanier et al. experienced an infection rate of 13% and 1 patient developed pulp dystrophy using this technique.21 Grant et al. in 2002 described a technique that used a percutaneous K-wire hoop to support an intratendinous Kessler suture (3-0 monofilament) that was tied over a rubber roll.22 The combination of the K-wire and rubber roll act to provide a continuous traction force to the FDP tendon whilst avoiding any pressure on the delicate nail matrix. In their series of 11 patients (4 tendon grafts) they did not encounter any infections or nail deformities, but 2 patients required adjustment of the bulky construct. Unfortunately, no outcome data is presented on the range of motion (ROM) and therefore a comparison with other techniques cannot be made. More recently, Zhang et al., have described a pullout wire traction technique for re-attaching the avulsed FDP.23

Their method used a 28-gauge steel wire suture that was passed through the distal portion of the tendon and then via drill holes onto the dorsal aspect of the finger. The suture was then secured to a K-wire that was bent in a manner to allow a constant traction force to be applied to the tendon. They believed this would lead to decreased tendon gapping and thus allow early active joint motion. They demonstrated excellent outcomes in 9/16 patients according to Strickland’s criteria, but the mean DIP flexion was only 32 . However, according to Evan’s, at least 40 of DIPJ motion is necessary for satisfactory function and using Moiemen’s criteria for assessing DIPJ ROM, 32 would be classed as a poor result.13,24 They did not encounter any infections despite the bulky construct, which the patients found cumbersome.

Internal fixation techniques To avoid the problems with the external constructs a number of alternative internal fixation methods have been developed. These can be broadly divided into suture techniques and those that use bone anchors.

Suture/wire techniques Sood and Elliot described their 2-strand interosseous technique in 1996.25 This required an additional fishmouth incision at the tip of the finger through which a transverse drill hole was made. The retrieved FDP was sutured using the Kirchmayr or Kessler technique with the suture then passed through longitudinal channels on the sides of the distal phalanx and then passed through the transverse tunnel in the tuft. In their series of 9 patients with avulsion injuries there were no documented complications despite the additional fishmouth incision. However, crucially since no outcome data was provided it is difficult to fully judge

1026

S. Huq et al.

Figure 4 Internal techniques.

Figure 3

Internal fixation techniques: suture only repairs.

the merits of this technique. Disadvantages of this technique are that the repair is limited to a 2-strand technique and the long distance between the tendon stump and point of fixation may lead to increased gapping (Figure 3).20 Schultz in 1999 described an internal technique that required an incision proximal to nailfold through which the transosseous suture was tied. The advantage of this method

fixation

techniques:

anchor

based

was the avoidance of any trauma to the nailbed tissues. Unfortunately, their paper did not discuss the outcomes of surgery or whether there were any complications and thus a full analysis of the technique is not possible.26 Teo et al. described an anatomical repair technique in which the retrieved tendon was sutured using a 3-0 Ethibond suture using a modified Kessler pattern.27 The suture ends were then passed obliquely through the distal phalanx exiting in the midlateral line (through drill holes) and then tied on the volar surface FDP. In their study with 9 primary repairs they achieved good/excellent results in 7 patients with a mean DIPJ ROM of 2 /53 . They did not document any complications in their series. Tripathi et al. also described a transverse intraosseous loop technique (TILT) technique using a 3-0 suture (prolene/ethibond).28 In this method the suture passes transversely through the entire width of the distal phalanx with the knot tied on the dorsal surface of the tendon in contrast to Teo et al.27 The key advantage of this technique is that no additional incisions are required. In their series of 12 patients they achieved a mean DIPJ ROM of 3 /62 with 2 patients developing fixed flexion contractures. They did not encounter any ruptures.

Summary of repair types with outcome data.

Technique

Author

Technical details

Patients

Follow up (months)

Strickland (% excellent/ good)

Moiemen (% Excellent/ good)

DIPJ ROM (degrees)

Ruptures (%)

Infection (%)

Nailbed deformity (%)

Pullout

Kang et al., 2008

23

3

n/a

n/a

n/a

0

22

35

Mantero

Schaller and Baer, 2010

65

40

54

38

0.6/53

0

n/a

0

Mantero

Montanier 2003

20

26

95

n/a

n/a

0

5

0

Grant

Grant et al., 2002

7

21

n/a

n/a

n/a

0

0

0

Zhang

Zhang et al., 2012

16

15

81

n/a

8/32

0

0

0

Sood

Sood and Elliot 1999

n/a

n/a

n/a

n/a

n/a

n/a

n/a

n/a

Schultz

Schultz et al., 1998

Variety of suture types (prolene, nylon, steel, Ticron). Suture removed at 6-8/52 3-0 prolene suture and Kichmayr technique with suture passing through distal tendon stump and exiting fingertip. Suture tied over a silicone disc and button and removed at 6/52. 2-0 Ethicrin and omega-shaped looped suture that is removed at 6/52. 3-0 Monofilament non-absorbable suture using modified Kessler method and tied over a rubber roll on a 1.25 mm K-wire inserted laterally into distal phalanx. Device removed at 6/52 2 X 3-0 Ethibond sutures in a Becker configuration hold a 28-gauge steel wire that is passed dorsally through the distal phalanx and then secured to an externalized K-wire construct. 4-0 Prolene Kessler/Kirchmayr suture passed longitudinally through the distal phalanx and then transversely through the tuft of the phalanx 3-0 Braided suture in a modified Kessler method in the tendon then passed through and tied on the dorsal surface of the distal phalanx

n/a

n/a

n/a

n/a

n/a

n/a

n/a

n/a

Zone 1 flexor tendon injuries

Table 1

(continued on next page)

1027

1028

Table 1 (continued ) Technique

Author

Technical details

Patients

Follow up (months)

Strickland (% excellent/ good)

Moiemen (% Excellent/ good)

DIPJ ROM (degrees)

Ruptures (%)

Infection (%)

Nailbed deformity (%)

Tripathi

Tripathi et al., 2009

20

11

n/a

n/a

3/62

0

0

0

Kapikis

Kapikis M, 2009

7

6

n/a

n/a

n/a

0

0

0b

Teo

Teo et al., 2008

10

8

n/a

78

2.2/55.5

0

0

0

Skoff

Skoff et al., 1995

2

24

n/a

n/a

a

/47

0

0

0

McCallister

McCallister et al., 2006

13 13

12 12

n/a n/a

n/a n/a

8/56 9/57

0 0

0 15

0 0

Lee

Lee et al., 2011

3-0 Prolene/ethibond passed in a Kessler manner through tendon and then transversely through the distal phalanx 3-0 Suture passed from dorsal incision through distal phalanx (DP) and secures tendon in a volar hole drilled into to the base of the DP. Bunnell core suture used. 3-0 Ethibond passed through tendon using modified Kessler technique and then through drill holes the sides of the distal phalanx with knot tied on volar surface of tendon. Acufex Bone Anchor with 3.0 Polyester suture using a Kessler locking suture 2 Micro bone anchors using 3-0 Ethibond and hemi-modified Kessler pattern. 2-0 Ethibond in modified Kessler pattern for pullout technique 2 Micro bone anchors with 3-0 FibreWire suture in a locking Krakow manner supplemented by 3-0 Mersiline suture also in a Krakow pattern tied over a button. Button removed at 6/52 but locked suture remains.

n/a

n/a

n/a

n/a

n/a

n/a

n/a

n/a

n/a Z Data not available. a No value given for flexion contracture. b 1 mallet deformity.

S. Huq et al.

Zone 1 flexor tendon injuries In 2009 Kapikis described another technique of tendon to bone fixation.29 In this method an incision was made proximal to the nailfold through which a 3-0 suture was passed through the distal phalanx. On the volar surface of the base of the distal phalanx a tunnel was created into which the tendon was introduced and secured using a Bunnell suture. In their study of 12 patients, of which 7 were avulsion injuries, they documented good results in 8 patients. However, they did not give the exact ROM or make reference to the criteria by which they classified their outcomes. Three patients developed flexion contractures and more importantly one developed a mallet deformity due to transection of the extensor insertion as a result of the dorsal incision.

Bone anchors The use of bone anchor sutures is well documented in shoulder and knee surgery and their use is becoming more widespread in hand surgery particularly with introduction of smaller micro bone anchors. This is an attractive option since it allows the use of multistrand locking sutures which are biomechanically stronger than the 2-strand pullout techniques and also do not require removal. There are two main types of anchors, the screw type design (e.g. Statak) and the non-screw type that deploy prongs once inserted into cancellous bone (Mitek products). The initial studies of anchors for FDP reattachment used larger anchors such as the Mitek mini anchor that measured 1.8 mm in diameter and 5.5 mm in length. Rehak et al., in 1994 demonstrated that in 6/66 of patients the mini-anchor penetrated the far cortex resulting in complications in 2 patients.30 However, in a recent study by McCallister in which Micro anchors were used (1.3 mm diameter and 3.7 mm length) there were no cases on far cortex penetration.14 Furthermore, if the anchors are inserted in a 45 retrograde fashion as advocated by Schreuder not only is the degree of gaping less but the oblique pathway of the anchor makes it even less likely to penetrate the far cortex (Figure 4).31 The strength of repair in the anchor techniques has been compared to the more common pullout method in a number of cadaveric studies. Brunstein compared the 2-strand pullout technique with 2 micro anchors in a 4-strand repair.32 They found a significantly higher force for failure in the anchor group (69 N vs 43 N) and with only one anchor dislodging from the bone. In a follow up study by Silva in 2008, the Fiber-Wire anchor group was found to have comparable force-to failure values to the pullout technique but significantly greater stiffness and less gapping (4.82 mm vs 9.34 m at failure).20 The forces experienced by the FDP during passive and active flexion have been shown to be 15 N and 28 N respectively in an in vivo study.33 Thus it is clear that both the pullout and the anchor groups have are sufficiently robust to withstand the forces generated during passive rehabilitation regimes. But the increased stiffness and reduced gap formation may favour anchor fixation with the active rehabilitation protocols.20,32 This may in part explain the mediocre outcomes seen with the pullout technique.13 McCallister et al. has performed the only study comparing distal FDP repairs using the micro anchor technique vs the standard pullout method.14 They found no

1029 differences in outcomes for the DIPJ ROM between the groups (57 for the pullout vs 56 for the anchor group). However, there was an infection rate of 13% in the pullout group (0% anchor group) and a quicker return to work for the anchor group. This study highlights the recognized risk of infection with the pullout technique, but overall functional outcomes are similar. Recently, there have been a number of case reports documenting the risk of osteomyelitis in patients treated with anchors. O’Sullivan reported a case in which the anchor migrated through the dorsal cortex exiting through the nail 6 years after anchor placement.34 In this case a Statak screw anchor was used which is of larger dimensions than the more commonly used Mitek micro anchors and this may therefore have been too large to place in the patients distal phalanx. The second report by Giannikas described a case of osteolysis presenting 14 months after FDP repair with Mitek micro anchor.35 In this case the anchor was successfully removed and the patient made an uneventful recovery. However, with the exception of these isolated cases there are no other published studies that point to a risk of osteomyelitis or long-term complications with the use of the anchors. Cadaveric studies have suggested that bone quality may impact on the strength of the bone anchor repair. In these studies the anchors were shown to fail by either suture rupture at the anchor attachment or by anchor pullout. However, in these studies the average ages of the specimens were greater than 70 years20,32 and would be expected to have decreased bone mineral density. Whereas, zone 1 injuries primarily tend to affect a younger co-hort and the potential problem of anchor pullout has not been borne out in the clinical setting.14 The main disadvantage of bone anchors vs the pullout or other internal fixation techniques is the cost of the device. A single Mitek MicroBone anchor costs in the region of £180 whereas the other techniques need only standard sutures (e.g. prolene) and/or K-wires. However, a recent cost analysis performed by Katolik et al. showed that despite the higher initial costs the bone anchors proved to be cheaper in the long term due to the reduced rate of complications. This study investigated acute repair of the ulnar collateral ligament, but the findings can be extrapolated to FDP repairs.36 More recently, Lee et al. has described a new technique that uses both a pullout suture and bone anchors.37 In this case, the FDP is secured to the distal phalanx using a locking Krakow suture that passes through 2 micro anchors with the suture tied on the dorsal surface of the tendon. The repair is augmented by a 3-0 mersiline suture also placed in a locking Krackow manner through the volar aspect of the tendon, which is then tied over a button. In the cadaveric studies this technique was shown to have significantly less gap formation than either the bone anchor or pullout techniques (0.02 mm vs 0.2 mm vs 1.1 mm). However, in their clinical experience they documented nailbed infections due to the retained mersiline suture and have not published ROM outcomes. Therefore, despite the variety of techniques available for the repair of acute distal zone 1-flexor tendon injuries, no one technique has emerged to be superior to the others. Furthermore, the lack of randomized studies or standardized outcome data in the published literature add to the

1030 difficulty in performing an accurate comparison of the techniques (Table 1). The data available from the published studies show that there is still considerable room for improvement in terms of outcomes. However, based on the available evidence decisions on selecting one technique over another can be made. External fixation methods suffer from a risk of infection due to the externalized suture/ wire16,21 and can be cumbersome,22,23 so patient selection is crucial. Repairs with 4 stands vs 2 strands have greater strength,17 and monofilament sutures are prone to gapping.18,19 Two micro bone anchors provide greater strength than a single anchor32 and retrograde placement of the anchors results in significantly less gap formation.31 Braided suture material and fiberwire have the greater strength and result in less gap formation31 but when used for the pullout technique can result in high rates of infection due to suture retention.37

Conclusions The repair of distal FDP tendon injuries remains a challenging task with a multitude of repair options available to the surgeon. The techniques differ in terms of cost and technical difficulty, which is relevant as a significant proportion of repairs will be performed by trainee surgeons. The pullout technique and modifications of it remain popular but there is a growing trend for using bone anchors. It is therefore imperative that the surgeon is aware of the differing techniques in order to select the appropriate repair method for each patient. No one technique has emerged to be superior to others. This is in part due to the lack of standardized outcome data for the repair types which has been highlighted by this review. Furthermore, the patient should be made aware from the outset that no one technique has been shown to consistently produce good or excellent outcomes.

Acknowledgements No conflicting interests, No funding required, No ethical approval required. All named authors hereby declare that they have no conflicts of interest to disclose

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S. Huq et al. 7. Murphy BA, Mass DP. Zone I flexor tendon injuries. Hand Clin 2005;21:167e71. 8. Ruchelsman DE, Christoforou D, Wasserman B, Lee SK, Rettig ME. Avulsion injuries of the flexor digitorum profundus tendon. J Am Acad Orthop Surg 2011;19:152e62. 9. Lubahn JD, Hood JM. Fractures of the distal interphalangeal joint. Clin Orthop Relat Res 1996;327:12e20. 10. Kang N, Pratt A, Burr N. Miniplate fixation for avulsion injuries of the flexor digitorum profundus insertion. J Hand Surg Br 2003;28:363e8. 11. Ehlert KJ, Gould JS, Black KP. A simultaneous distal phalanx avulsion fracture with profundus tendon avulsion. A case report and review of the literature. Clin Orthop Relat Res 1992;283:265e9. 12. Al-Qattan MM. Type 5 avulsion of the insertion of the flexor digitorum profundus tendon. J Hand Surg Br 2001;26:427e31. 13. Moiemen NS, Elliot D. Primary flexor tendon repair in zone 1. J Hand Surg Br 2000;25:78e84. 14. McCallister WR, Ambrose HC, Katolik LI, Trumble TE. Comparison of pullout button versus suture anchor for zone 1 flexor tendon repair. J Hand Surg 2006;31:246e51. 15. Schaller P, Baer W. Motion-stable flexor tendon repair with the Mantero technique in the distal part of the fingers. J Hand Surg Eur Vol 2010;35:51e5. 16. Kang N, Marsh D, Dewar D. The morbidity of the button-over-nail technique for zone 1 flexor tendon repairs. Should we still be using this technique? J Hand Surg Eur Vol 2008;33:566e70. 17. Choueka J, Heminger H, Mass DP. Cyclical testing of zone II flexor tendon repairs. J Hand Surg Am 2000;25:1127e34. 18. Silva MJ, Hollstien SB, Brodt MD, Boyer MI, Tetro AM, Gelberman RH. Flexor digitorum profundus tendon-to-bone repair: an ex vivo biomechanical analysis of 3 pullout suture techniques. J Hand Surg Am 1998;23:120e6. 19. Latendresse K, Dona E, Scougall PJ, Schreuder FB, Puchert E, Walsh WR. Cyclic testing of pullout sutures and micro-mitek suture anchors in flexor digitorum profundus tendon distal fixation. J Hand Surg Am 2005;30:471e8. 20. Matsuzaki H, Zaegel M, Gelberman R, Silva M. Effect of suture material and bone quality on the mechanical properties of zone 1 flexor tendon-bone reattachment with bone anchors. J Hand Surg Am 2008;33:709e17. 21. Guinard D, Montanier F, Thomas D, Corcella D, Moutet F. The Mantero flexor tendon repair in zone 1. J Hand Surg Br 1999; 24:148e51. 22. Grant I, Pandya A, Mahaffey PJ. The re-attachment of tendon and ligament avulsions. J Hand Surg Br 2002;27:337e41. 23. Zhang X, Shao X, Zhang K. Pull-out wire traction for the treatment of avulsion of the flexor digitorum profundus from its insertion. J Hand Surg Eur Vol 2012 Jul 3. 24. Evans RB. Zone I flexor tendon rehabilitation with limited extension and active flexion. J Hand Ther 2005;18:128e40. 25. Sood MK, Elliot D. A new technique of attachment of flexor tendons to the distal phalanx without a button tie-over. J Hand Surg Br 1996;21:629e32. 26. Schultz RO, Drake DB, Morgan RF. A new technique for the treatment of flexor digitorum profundus tendon avulsion. Ann Plast Surg 1999;42:46e8. 27. Teo TC, Dionyssiou D, Armenio A, Ng D, Skillman J. Anatomical repair of zone 1 flexor tendon injuries. Plast Reconstr Surg 2009;123:617e22. 28. Tripathi AK, Mee SN, Martin DL, Katsarma E. The “transverse intraosseous loop technique” (TILT) to re-insert flexor tendons in zone 1. J Hand Surg Eur Vol 2009;34:85e9. 29. Kapickis M. New “loop” suture for FDP zone I injuries. Tech Hand Up Extrem Surg 2009;13:141e4. 30. Rehak DC, Sotereanos DG, Bowman MW, Herndon JH. The Mitek bone anchor: application to the hand, wrist and elbow. J Hand Surg Am 1994;19:853e60.

Zone 1 flexor tendon injuries 31. Schreuder FB, Scougall PJ, Puchert E, Vizesi F, Walsh WR. The effect of mitek anchor insertion angle to attachment of FDP avulsion injuries. J Hand Surg Br 2006;31:292e5. 32. Brustein M, Pellegrini J, Choueka J, Heminger H, Mass D. Bone suture anchors versus the pullout button for repair of distal profundus tendon injuries: a comparison of strength in human cadaveric hands. J Hand Surg Am 2001;26:489e96. 33. Schuind F, Garcia-Elias M, Cooney WP, An KN. Flexor tendon forces: in vivo measurements. J Hand Surg Am 1992;17:291e8. 34. Tiong WH, O’Sullivan ST. Extrusion of bone anchor suture following flexor digitorum profundus tendon avulsion injury repair. J Plast Reconstr Aesthet Surg 2011;64:1242e4.

1031 35. Giannikas D, Athanaselis E, Matzaroglou C, Saridis A, Tyllianakis M. An unusual complication of Mitek suture anchor use in primary treatment of flexor digitorum profundus tendon laceration: a case report. Cases J 2009;2:9319. 36. Katolik LI, Friedrich J, Trumble TE. Repair of acute ulnar collateral ligament injuries of the thumb metacarpophalangeal joint: a retrospective comparison of pull-out sutures and bone anchor techniques. Plast Reconstr Surg 2008;122:1451e6. 37. Lee SK, Fajardo M, Kardashian G, Klein J, Tsai P, Christoforou D. Repair of flexor digitorum profundus to distal phalanx: a biomechanical evaluation of four techniques. J Hand Surg Am 2011;36:1604e9.