Treatment of unfavourable results of flexor tendon surgery: Ruptured repairs, tethered repairs and pulley incompetence.

As primary repair of divided flexor tendons becomes more common, secondary tendon surgery becomes largely that of the complications of primary repair, namely ruptured and adherent repairs. These occur with an incidence of each in most reported series world-wide of around 5%, with these problems having changed little in the last two decades, despite strengthening our suture repairs. Where the primary referral service is less well-developed, and as a more occasional occurrence where primary treatment is the routine, the surgeon faces different problems. Patients arrive at a hand unit variable, but longer, times after the primary insult, having had no, or bad, previous treatment. Sometimes the situation is the same, viz. an extended finger with no active flexion, but now no longer amenable to primary repair. Frequently, it is much more complex as a result of injuries to the other tissues of the digit and, also, as a result of the unaided healing process within the digit in the presence of an inactive flexor system. We present our experience in dealing with ruptured repairs, tethered repairs and pulley incompetence.

INTRODUCTION

As primary repair of divided flexor tendons becomes more common, secondary tendon surgery becomes largely that of the complications of primary repair, namely ruptured and adherent repairs. These occur with an incidence of each in most reported series world-wide of around 5%, with these problems having changed little in the last two decades, despite strengthening our suture repairs (Elliot and Giesen, 2013a).[1]

Failures of primary surgery can be simply unlucky but they include many who will do poorly with any surgery. These patients generally fall into two groups. The first have had ‘bad’ injuries, many of which might have led to finger amputation or never been considered for surgery in 1950, so would never have come to secondary flexor surgery. The second group are ‘bad’ patients. This is not a moral judgement but an observation of features held in common by many of this group, many of which are outwith the control of the individual patient. Some make more scar than the ‘normal’, some have low pain thresholds, some present late because they have not realised that their finger is not bending properly, some cannot attend for therapy or cannot comprehend what is being asked of them. Also, of course, there are those who will not attend for therapy and will not comply with instructions. If they proved poor candidates for primary flexor surgery, they are likely to do badly again with secondary surgery.

Where the primary referral service is less well-developed, and as a more occasional occurrence where primary treatment is the routine, the surgeon faces different problems. Patients arrive at a hand unit variable, but longer, times after the primary insult, having had no, or bad, previous treatment. Sometimes, the situation is the same, viz. an extended finger with no active flexion, but, now, no longer amenable to primary repair. Frequently, it is much more complex as a result of injuries to the other tissues of the digit and, also, as a result of the unaided healing process within the digit in the presence of an inactive flexor system.

EXTENSOR TENDON TETHERING

This problem, due to fibrin in the oedema following injury filling the loose areolar tissue superficial and deep to the extensor tendons and sticking the tendons to the skin and skeleton to prevent passive flexion of the fingers, was discussed in a previous article (Elliot and Giesen, 2013a).[1] As this complication is far the greatest cause of morbidity after all flexor tendon surgery, wherever and however it is done and whoever does the surgery, it is reiterated here. This will vary in degree, according to the magnitude of the injury, the individual patient's tendency to form oedema, and the rehabilitation efforts of the patient and the medical team to move the hand quickly and pump the glue out before it starts ‘setting’. It has always been said that the Caucasian hand is more liable to this problem than those of the Indian sub-continent and this is probably true. However, it does not mean this can be ignored in India. We have seen hands with extensor tendon tethering in India and, perhaps, its relative rarity makes the surgeon less likely to recognise that this factor, and not the primary pathology and/or operation, is hampering the recovery of the hand.

The hand functions mostly by flexion of the digits to allow them to power, pinch and span grip, with the extensors setting the digits back to zero, ready to flex again for the next gripping activity. Our hands can tolerate quite a restriction from full extension before this becomes a functional problem. There has to be considerable adherence of the extensor tendons before we see any significant loss of extension at all. This is only usually seen in very grossly swollen hands. The functional problem caused by extensor tethering is largely one of loss of digital flexion because the adherent extensor tendons cannot glide distally to allow finger flexion. Even the slightest extensor tethering will restrict flexion significantly. With the more moderate swelling normally seen after flexor tendon injury, this can be a problem requiring considerable therapy effort to prevent loss of flexion at some point in the recovery. By 3 to 4 months, the problem may have resolved. However, at this time and in cases without obvious swelling in the early post-operative period, extensor tethering will only be recognised if one is looking for it, first, in the complaints of the patient, and second, by examining for it. These patients will complain that they have pain along the dorsum of the digits and/or hand on tight or prolonged gripping and their grip remains weak. They may have reasonable, though usually not perfect free active flexion, but testing passive flexion of the involved fingers will identify the fine degrees of extensor tendon tethering causing these problems. The two tests we use for this are described in detail in a previous article (Kulkarni et al., 2006).[2] They are adapted to become diagnostic tests from the means whereby therapists treat this problem. Once identified, the tendon tethering should be addressed by further therapy. The problem will rarely go away untreated as, with time, the ‘glue’ sets as the fibrin converts to fibrosis. If severe, there is a need for surgical extensor tenolysis. When oedema is not obvious visually, this problem is often missed and the patient retains the same complaints and a permanent disability. It goes without saying that any secondary surgery to the flexors, whatever the problem, cannot be done if there is significant extensor tethering. The maximum active flexion which will be achieved by secondary flexor tendon surgery will also be that allowed by the limitation of flexion resulting from the extensor tethering and the tightening of the dorsal capsules of the joints.

FLEXOR TENDON RUPTURE AFTER PRIMARY REPAIR

Although concern about tendon rupture has been one of the major determinants in the evolution of the various techniques of tendon suture and early postoperative mobilization throughout the last 10 years of the 20th century, there was almost no information in the literature early in this century as to whether immediate re-repair of ruptures is successful. In 1982, Leddy stated that ‘the preferred treatment (of ruptures) is prompt re-exploration and repair’ (Leddy, 1982)[3] without proof that this was correct, although a number of earlier studies had suggested that immediate re-repair of a ruptured flexor tendon and a further full period of mobilisation is likely to achieve results almost as good as the original repair, whatever the flexor tendon injury and whatever the technique of mobilisation, when a patient presents within 72 h of rupture within the first five weeks following primary surgery. In 2006, we reviewed 44 rupture re-repairs of zone 1 and 2 primary flexor tendon repairs in our unit between 1989 and 2003, with the re-repairs done with the same two strand repair as we used for the primary repair, to assess the outcome of immediate re-repair, with a view to identifying whether this should be an invariable policy (Dowd et al., 2006).[4] This study found this general rule to be broadly true, although these cases only achieved good or excellent results in 51% of cases overall, with a re-rupture rate of 12.5%. In other words, the results of re-repair were not as good as primary repair but immediate re-repair was still worth consideration. With nearly 50% of patients rupturing the primary repair as a result of an act of stupidity and an action contrary to therapy advice (Harris et al., 1999),[5] perhaps this result is all one could expect. However, closer analysis of this data showed that re-repair in the index, middle and ring fingers achieved 66% good or excellent results and few re-ruptures. Re-repair in the little finger was the problem: In this finger, re-repair achieved only 31% good or excellent results, with four of the five ruptures after all of the re-repairs occurring in the little finger.

Certain pre-operative factors require consideration before undertaking immediate re-repair and may preclude this, viz. the general medical condition of the patient, advanced or very young age, an noncompliant patient, other hand pathologies such as gross multi-joint osteoarthritis, infection, wound dehiscence, a finger which is too swollen and stiff, a delay between rupture and presentation of more than 72 h to presentation, and rarely, rupture occurring five or more weeks after primary surgery when the finger is in the ‘wooden’ phase of intense healing. Patient reluctance is most likely where a profundus tendon ruptures and PIP flexion by an intact FDS tendon is adequate for his/her function. In excluding various patients pre-operatively from immediate re-repair, one is mostly moving them toward a flexor tendon graft. In these situations, one is usually in the same position as with a ‘stuck’ tendon of having to wait for the finger to recover and soften before undertaking surgery. The finger, which is often swollen and moving poorly, is mobilised by passive therapy for as long as necessary to regain its maximum mobility, usually three or more months. The patient buddy straps the finger to an adjacent finger during active use of the hand, which can be started immediately, to keep the finger from remaining extended and catching during hand activity. When the finger has recovered its mobility and pliability and the scars are soft, secondary flexor tendon reconstruction can be considered.

If one does re-operate after rupture, the patient needs to realise pre-operatively that it may prove impossible to carry out a re-repair for reasons which only become apparent during surgery and alternative options of treatment must be discussed pre-operatively. Under these circumstances, tendon grafting is likely to give the best result. However, the patient may not want this, or be unable to spare further time, so the alternatives of doing nothing further, except to close the finger, or carrying out a procedure — either distal tendon tenodesis or distal interphalangeal joint fusion — to prevent distal joint hyperextension should be discussed.

Re-repair is not always easy and it is best performed by an experienced surgeon. At surgery, the tendons may be too swollen or friable to hold sutures, or too adherent to their surrounds, or the proximal tendon end may have retracted too far. This list is more theoretical than a result of our own experience, as most of the ruptures we explore are re-repaired. The problem of swollen tendons which are unlikely to glide postoperatively within the confines of the tendon sheath if re-repaired conventionally can usually be overcome by excising the proximal part of the FDS tendon to make more room within the sheath for the repaired profundus tendon. The distal part of the FDS tendon is sutured to the sheath at the level of the proximal phalanx to avoid late swan-necking of the PIP joint. In Caucasian fingers with previous injury to this side of the digit, this is an unlikely complication, but this precaution should generally be taken in the Indian finger. Retraction of the proximal tendon end, most commonly a problem of the FPL tendon, can often be overcome by lengthening the proximal tendon.

We customarily tendon graft in two stages. It is often an appropriate saving of time to perform the first stage, inserting a rod, when it is realised at surgery that re-repair will not be possible. If one-stage tendon grafting is favoured or necessary, this is sometimes possible under these circumstances but more likely to achieve a good result in the fully healed and supple finger and nothing is lost by inserting a rod at this operation to make the later grafting procedure simpler.

We have previously discussed technical difficulties repairing the small tendons in the little finger (Elliot, 2002).[6] The small size of the digit also makes rehabilitation after primary repair more difficult and this experience was repeated in re-repairing ruptures of the primary repairs (Dowd et al., 2006).[4] In this study, the percentage of ruptures of primary repairs was very much greater in the little finger (46%) than in the other fingers. Re-repair had a 35% chance of creating a little finger which is a hindrance because of loss of sufficient extension and hooking and/or insufficient flexion ability to provide good grip function and prevent objects dropping out of the ulnar side of the hand. Re-repair also had a 20% chance of a second rupture. Unfortunately, four and six strand repairs are less easy to accommodate in the flexor tendons of this finger, especially under the circumstances of a re-repair. We would not re-repair a rupture of the profundus tendon with a strong intact FDS tendon. However, even when only the FDP tendon of the little finger has ruptured, doing nothing may not be an option as the FDS tendon may be absent, or too weak to provide sufficient PIP joint flexion for useful function. Regrettably, secondary surgery to the flexor tendons of this finger is no less difficult.

The little finger remains unsolved. We continue to re-repair in this finger in some cases, as the management, when successful, is simpler for the patient than the alternative of grafting. However, we are more inclined to move to tendon grafting than in the other fingers for indications already discussed, with insertion of a rod only at the first operation. We also acknowledge the problems of this finger from the start and increase therapy time for these patients after primary repair. If patient compliance, or other problems, has become apparent during primary rehabilitation, we feel that rupture of the little finger should be treated by two-stage secondary reconstruction, a rod being inserted into the finger as an alternative to re-repair. When evidence that stronger re-repairs give better results in the little finger is available, this policy may require modification.

THE ‘STUCK’ OR ADHERENT PRIMARY TENDON REPAIR

The other failure of primary flexor tendon surgery is tendon adherence with loss of full active finger flexion, extension or both. As sticking almost always occurs during the first 8 weeks after primary repair, the therapists cannot be more aggressive for fear of rupture. They can, however, increase the frequency of therapy, which can be useful. The patient has to be told that it is not advisable to re-open the finger until it has lost its redness and swelling and is soft again, which can take 3, 6 or more months. If operation is too early, it can be difficult to identify and separate the structures, or to suture them, and the hand often responds with a worse healing reaction and more tendon adherence. The skin scars, the swelling of the finger and its pliability are good indicators of the stage of healing inside. The extra time in therapy is useful. The losses of flexion and extension are rarely complete and sometimes improve with further time and therapy. Enough may be restored to be acceptable for the patient's needs. Even if not, some patients will decide to do nothing further as they find they can manage, or are not prepared to lose more work time on the problem.

There are actually two possible problems in these digits: Which is present only becomes obvious at surgery. The tendon may simply be stuck to the surrounding sheath and require freeing, or the repair may have gapped causing the tendon to move less and become secondarily adherent. The latter is a hidden rupture and has to be treated as a late presenting rupture. The latter possibility should be discussed with the patient pre-operatively, so that the possible need for procedures other than simply tenolysis is clearly understood. On discovering a gapped tendon at tenolysis, we would continue to free all of the scarred contracted tissues, as described immediately below, then either proceed to single stage tendon grafting or insert a tendon rod as the first stage of a two-stage grafting procedure, which is our usual preference.

Before contemplating exploration of stuck repairs, it is important to realise, and the patient should also know, that all of the tissues on the front of the finger can be scarred to a variable degree and each layer may require treatment. So the terms ‘tenolysis’ and ‘tendon grafting’, which appear routinely on operating schedules, are often a gross simplification for the surgery needed and the time and surgical skill involved. The degree of this scarring is often surprising in a hand or finger which appears to have achieved resolution of the initial thickening and stiffness from the injury and/or primary surgery. The skin itself is occasionally of poor quality and requires replacement but it is much more common to find a loss of skin pliability with longitudinal skin shortage as a result of scarring of the subcutaneous tissues. Our preference for opening these fingers using a mid-lateral incision which comes onto the palm as a ‘V’ (Moiemen and Elliot, 1994)[7] allows the skin and subcutaneous tissues to be moved distally as necessary, leaving a gap in the suture line which lies on the fat of the palm, well away from the tendon surgery, is discussed in a previous article (Elliot and Giesen, 2013b).[8]

The sheath anterior to the tendons is also often thickened by scar tissue, contributing to the loss of extension of the digit. We commonly excise all of the thickened sheath except the A2 and A4 pulleys to expose the tendons, thereby resolving this cause of shortening [Figure 1]. It is generally recognised that the A2 and A4 pulleys, or at least a good part of them, by which is probably meant over 50%, must be retained to allow the flexor system to function in bending the finger. For reasons discussed later, we also try to retain the A3 pulley during this sheath resection.

Figure 1

A finger undergoing ‘tenolysis’ after sheath excision with preservation of the A2, A3 and A4 pulleys (the latter is not shown). The thickness of the scarred sheath is illustrated

Most, but not all, will have adherent tendons, in which case freeing of the adhesions, or ‘tenolysis’, will be necessary. This short sentence belies the difficulty which can be encountered in trying to achieve a free running tendon. Some surgeons prefer Beaver blades for this procedure. The authors routinely use a standard 15 guage blade and Stilley scissors. Probably the most important asset to carrying out a tenolysis is sufficient time and patience. It is particularly difficult to free the tendons on their dorsal surfaces under the pulleys and even the slightest small strand of fibrous tissue linking the tendons to one of the pulleys will stop movement. Although rarely admitted, division of a pulley - usually the A4 - at this stage is probably the commonest cause of pulley loss. When the tendons are very swollen and tight under the A2 pulley and seem likely to stick again, we remove the FDS tendon.

The deepest problem and the most likely to give rise to a recurrence of loss of extension are the ligaments of the underlying joints which can be scarred to a thickness of several millimetres. The PIP joint may only require proximal release of the palmar plate but, more often, the accessory collateral ligaments also have to be released. If the scarring is more severe, releasing the true lateral ligaments may be necessary. Sometimes, we carry out complete excision of a very thick and scarred PIP palmar plate, using distal tenodesis of the FDS to replace the palmar plate if the excision makes the joint dorsally unstable. I have found anything short of complete excision of a contracted DIP palmar plate does not straighten the DIP or keep it straight in the long-term. This procedure is not done by us sufficiently frequently to recommend it over DIP joint fusion in the very difficult cases with flexion contracture of both interphalangeal joints and a true ‘hook’ finger.

In a small number of cases, the digit will still not extend, even after such extensive releases because of musculo-tendinous shortening. As the secondary tendon surgeon was often not the primary surgeon, or has no precise memory of the event, it is impossible to say whether this is due to true muscle shortening as a result of the digit having been in a flexed position for a long period of time before primary repair or is a result of tendon trimming at primary surgery. It is the author's impression, from cases treated entirely in our own unit that muscle shortening does occur, although it is not clear why this should occur in some patients and not others. This is a particular, and well recognised, problem for the long flexor of the thumb. When this does occur, it is often only by a small degree, which is amenable to lengthening of the tendon within the muscle, as described by Le Viet, in 1986 [Figure 2].[9] The intramuscular part of the tendon is cut across and the tenotomy gapes to separate the tendon ends by approximately one centimetre, with continuity being maintained by the muscle fibres alone. Should two to three such tendon divisions within the muscle give insufficient increase of tendon length, conventional step lengthening of the tendon is then carried out. We do this at the musculo-tendinous junction, instead of just proximal to the distal wrist crease in the free tendons, in order to allow the step procedures to be wrapped in the muscle to speed healing and improve gliding.

Figure 2

Le Viet's intramuscular tendon lengthening procedure

All of these cases are treated with antibiotics for 5 days post-operatively as infection will create so much more fibrin-oedema glue that the tendons are likely to adhere again. There is no repair to protect and much more aggressive active and passive rehabilitation can be started immediately. This is started the day after operation under a continuous local anaesthetic infusion through a percutaneous cannula onto the median or ulnar nerves, or their branches in the palm, proximal to the site of surgery, as an in-patient to achieve as much motion as possible as early as possible (Kulkarni and Elliot, 2003).[10] The economics of such a policy may be questioned. However, much hangs on this secondary operation. If it fails, the patient's money, or that of the State, has been dissipated and a considerable amount of surgical and therapy time entirely wasted. Most important of all, the patient is unlikely to be offered a repeat operation and is left with his/her original, occasionally a worse, deficit of hand function. This is usually the ‘last’ operation for this hand!

The ‘frayed tendon programme’ of rehabilitation was advocated by Strickland and his co-workers (Cannon and Strickland, 1985)[11] in cases with frayed, or thin, tendons and/or poor soft tissue cover of the palmar aspect of the digit. This involves passive full flexion of the digit, then active maintenance of the flexed position by the patient instead of active flexion through the full range of motion. While, theoretically, this may be safer in such cases, it places an onus on the therapists to carry out a regimen of treatment which is not their norm without rupturing poor tendons. Consequently, we prefer to replace such tendons by rods and carry out secondary grafting with routine therapy management later in the more severely damaged cases, so placing the onus of judgement as to whether these tendons will survive the post-operative period back in the operating theatre.

It is sometimes the case that tendons with severe scarring, or which are badly frayed, cannot be freed without irrevocable damage to the tendons or the vital pulleys. In these cases, tendon grafting and/or pulley reconstructions will be necessary after freeing the palmar side of the finger from the scarring in the other tissues and excising the tendons. Necessity, or preference, may determine that this may be done at the same operation. We believe that most such cases lend themselves to two-stage tendon reconstruction, firstly because the degree of scarring is severe and, often, also because a pulley reconstruction over a rod, which does not have to cope with the forces of tendon activity immediately, is much simpler to manage, as will be explained later.

THE OPTIONS OF TREATMENT IF PRIMARY REPAIR IS IMPOSSIBLE OR FAILS

Outwith the short period when the appropriate patient and appropriate conditions allow primary flexor tendon repair and with failures of salvage of rupture or tendon tethering after primary repairs, the options of treatment of the divided flexor tendon include doing no flexor tendon repair, delayed primary repair, and flexor tendon grafting in one or two stages. It is obviously important that there be full discussion with the patient of all of the treatment options where any secondary flexor tendon procedure is contemplated, as the length of time involved may have significant life and work implications. In particular, it should be understood that tendon grafting is a complicated treatment option with imperfect results which involves lengthy periods off work.

DOING NO FLEXOR TENDON REPAIR

Under most circumstances, when this decision is made at any time, the patient buddy straps the flail finger to the adjacent finger to stop it catching during activity, or, in the case of a thumb with no flexor function of the distal joint, allows the thumb to flex at the metacarpophalangeal joint only. The option of doing nothing is mostly used temporarily while waiting for digits to soften and become amenable to further surgery. It is used occasionally as a long-term solution, usually in the elderly. In others, delayed re-repair or grafting is likely to give the best result but, occasionally, the patient may not want, or be unable, to spare further time for further surgery. A decision to do nothing can be reversed after any length of delay until old age intervenes.

When only an FDS tendon has been divided, it is not usually necessary to repair the tendon, as the FDP tendon will fully flex the finger. However, some loss of power and dexterity is likely and consideration of these facts may necessitate repair for particular hand uses. Where only the FDP has been divided, the FDS may provide adequate finger flexion for some individuals, although only flexing the MP and PIP joints, but not for others. In a proportion of these patients, the DIP joint will hyperextend in fingers working without a FDP tendon, when pressure is applied to the fingertip. Tenodesis of the distal part of the FDP tendon by suture to the sheath at the level of the middle phalanx or actual fusion of the DIP joint, although providing no DIP joint flexion, will prevent this and is a simple alternative to tendon grafting in those patients content with MCP/PIP flexion only. Distal tenodesis of the FPL may also achieve the stability required for pinching in a thumb with a divided FPL flexing the thumb adequately by CMC and MCP flexion only. If the distal stump of the FDP or FPL is found to be inadequate for this purpose at the time of surgery, it can be reinforced by a length of palmaris tendon to permit this procedure. The alternative is a distal joint fusion.

The decision to tendon graft in cases with an intact and functioning FDS and divided FDP tendon has been greatly debated in the past and many surgeons will not contemplate it for fear of compromising FDS function. The author's experience has been that grafts running through an intact FDS tendon rarely adhere following two-stage tendon grafting followed by early mobilisation by good therapists in a well-motivated patient. Our therapists determine the motivation of the patients from previous encounters if the case is a failure of primary surgery and by arranging a period of pre-operative mobilisation of the digit passively if it is not.

DELAYED PRIMARY REPAIR

Where a patient presents for the first time after a considerable delay with a divided flexor tendon, it is sometimes possible to carry out a delayed primary repair. This has been discussed recently by us in detail in this journal (Elliot and Giesen, 2013a).[1] If the routine of the surgeon is to carry out one-stage tendon grafting, re-repair without tension would appear to have advantage over bridging the gap with a graft when possible.

TENDON GRAFTING

When both flexor tendons remain divided, there is usually no dilemma for discussion if reconstitution of a fully flexing finger is desired. On most occasions where no primary surgery has been carried out to the divided flexor tendon, the situation is similar to that of the ruptured primary tendon repair or the adherent tendon with gapping of the tendon after primary repair, with or without a need to deal with extensor tendon tethering and/or scar contracture of the other tissues of the palmar surface of the finger.

Tendon grafting may be done in a single stage or in two stages, with definite preferences by different surgeons for one or other technique. Which is preferable is a philosophical question to which we believe we do not have an answer. The results of secondary flexor tendon surgery are very much dependent on the starting state of scarring of the finger, the patient's intrinsic scarring tendency after further surgery, his/her psychological make-up and his/her ability to interact with the surgeons and/or therapists for a multitude of reasons post-operatively. While single stage tendon grafting has advantages for the patient in terms of a single period off work, it carries a risk of graft adherence, requiring further surgery and further time off work, as the new tendon is being placed in a bed of healing tissue from which the old tendon system has only just been removed. Although it seems to be ‘overkill’ when the sheath is not badly scarred, those who favour two-stage grafting would argue that it is impossible to tell either how much scarring there will be after the grafting surgery, or what effect even very small degrees of scarring will have on the ability of any particular patient to maintain movement of the digit post-operatively. No one has established how to identify the patient who will either scar badly or do no therapy!

Perhaps it is worth remembering that the two-stage graft was introduced because of dissatisfaction with the results of the one stage procedure. It is based on the premise of improving the bed into which the tendon graft is placed by the creation of a pseudo-sheath by inserting a flexible silicone rod into the hand at a first operation and delaying the actual grafting procedure for several months. Two stage grafting was pioneered in the 50s by Bassett and Carroll[12] (1963) and the present technique of two-stage tendon grafting was perfected by Hunter and his co-workers (Hunter, 1965).[13] The perceived advantage over single stage grafting is that mobilisation post-operatively is started with the graft moving in a smooth-walled pseudo-sheath and in a less traumatised, less painful and more supple hand. Despite a very small incidence of reaction to silicone rods and a small incidence of infection and/or extrusion of the rods, the two-stage procedure appears at least to reduce the influence on results of the ‘scarring’ factors, if not the other considerations beyond the surgery which affect outcome of tendon grafting.

Our own preference for two-stage surgery is partly based on these arguments and partly on surgical upbringing at a time and in a place where it was believed to give the best results, although published evidence for this is scarce. It may also be influenced by the fact that most cases of tendon grafting in our unit follow failure of primary surgery and these patients have already demonstrated one failure to maintain adequate mobilisation of a tendon repair, for whatever reasons. However, perhaps we should be considering a move back again to a single stage graft in more cases now our sutures are stronger and our rehabilitation more robust.

Under particularly adverse circumstances, those inclined to single-stage grafting might consider the two-stage procedure as more likely to provide near-normal finger function than one-stage grafting, then secondary tenolysis of the adherent graft. The total period off work is arguably less with two-stage grafting. Whenever inserted, the period of protecting the tendon graft is the same. Insertion of a rod requires 2 weeks, or less, off work of a sedentary kind and a little more for the manual labourer. Return to work in this time is unlikely after tenolysis.

When carried out as a single procedure, one, or both, tendons are removed from the digit through incisions in the tendon sheath intended to minimise the damage to the sheath and, at the very least, preserve the A2 and A4 pulleys. The FDS tendon is only removed if not intact or grossly swollen, and the distal part of this tendon must be retained or replaced to prevent future swan-necking of the PIP joint if this joint can be hyperextended at the time of surgery. Distal attachment of the FDP tendon and tensioning of the graft are done in a variety of ways (Wilson and Sammut, 2003).[14] We leave 0.5 cm of the FDP tendon attached to the distal phalanx after excising the remainder of the tendon. A tunnel is prepared behind this tendon remnant into which the distal end of the tendon graft will be ‘snugged’. A graft of the palmaris longus tendon from the same upper limb is harvested where possible for convenience and to minimise morbidity. If this is not present, the other palmaris tendon, one or other plantaris tendon, or other tendons (a long extensor of a second, third or fourth toe, the ipselateral extensor indicis or extensor digiti minimi) are recommended for use, with the donor sites usually being examined in the order given above until a suitable donor tendon is found. Our preference, where neither palmaris is present, is to use the extensor indicis tendon, as it is almost always present and rarely missed functionally. The discarded proximal FDS tendon of the injured finger can also be used as a free graft but may be swollen, causing problems when passed through the pulleys in the finger. The tendon graft is passed from the palm through the tendon sheath. Conventionally, it is sutured to the distal phalanx with a suture passed through the phalanx, through the nail and tied over a button on the nail. More commonly, we pass the sutures along the sides of the phalanx and through a hole in the tuft of the distal phalanx, to avoid the button (Sood and Elliot, 1996).[15] The tendon can be attached more proximally to the distal phalanx in a similar manner, or using a bone tag. The graft is sutured to the proximal part of either the FDP, or FDS, tendon (each has its advocates) with a Pulvertaft weave, either in the palm or at the wrist. The former is easier when using the palmaris longus tendon as it is not long enough to reach the wrist unless harvested more proximally in the forearm, then the proximal end ‘cleaned’ of attached muscle fibres. If the FDP tendon is used proximally as the motor of the graft, tendon junction at the wrist automatically avoids the possibility of the motor pulling through the lumbrical and extending the finger at the interphalangeal joints during activity, the so-called ‘intrinsic-plus phenomenon’. Some authors who use palmar proximal tendon junction detach the lumbrical from the FDP in the palm to avoid this problem, seemingly without functional disadvantage. We mostly use palmar tendon junction without lumbrical detachment, except when the lumbrical is badly scarred, and have only rarely seen the intrinsic plus phenomenon. When the lumbrical is badly scarred, we remove the muscular part in toto, again without causing functional problems. When performing the Pulvertaft weave, the graft is woven through the tendon of the proximal motor three or more times. Initially, it is set under tension with one or two horizontal mattress sutures of 3/0 or 4/0 strength, such that the finger-tip lies in the appropriate position in the cascade from little finger most flexed to index finger least flexed when the anaesthetised hand lies on the table with the wrist in the neutral position. This can be more difficult after severe finger injuries, or when the other fingers are only partially present, or do not lie in this cascade for other reasons. While preparing this first stage of the tendon weave, it is important to accommodate for the fact that the tendon weave is inevitably lifted slightly out of the palm while suturing, so the tendon length is always slightly greater when the weave is returned to the palm. Except when the wrist is fused, correct tendon length is confirmed by lifting the hand off the table and moving the wrist passively to move the fingers, by the wrist tenodesis effect, while watching to determine that the involved finger remains in the correct position in the cascade. If necessary, the sutures are removed to allow change of length at the weave. Achieving full extension and full flexion of a finger after tendon grafting is very difficult and it is common to lose one extreme or the other, indicating that the graft was slightly too tight, or slightly too slack. Many surgeons, accepting this, make the grafts slightly tighter in the ulnar two fingers and slightly less tight in the radial two fingers than will hold the finger-tip position in the cascade. After ensuring the correct tension of the proximal weave, it is completed, conventionally, by addition of a horizontal mattress suture for each tendon weave. The senior author prefers to use a continuous Prolene suture passed back and forth through the weaves from one end to the other then back to the starting end, to reduce the number of external suture knots to a single knot. Other surgeons find it more convenient to tension the tendon by performing the proximal weave first and tensioning the tendon distally, using one of the modifications of the distal attachment technique originally described by Pulvertaft (Pulvertaft, 1965;[16] Wilson and Sammut, 2003).[14] The above replacement of the whole of the tendons within the sheath is generally preferred to simply replacing any missing segment of tendon with a shorter graft, leaving one, or two, tendon repairs within the sheath, although there are those who use this approach.

After completion of the tendon graft suturing, the skin is closed and the repair protected in a dorsal plaster slab. Post-operative management is controversial, with grafts being treated conventionally for 3 to 4 weeks without movement. However, better results following mobilisation in Kleinert traction and by early active mobilisation, with or without rubber bands, have been reported (Tonkin et al., 1988;[17] Khan et al.,[18] 1997) and our experience of mobilisation by active extension — active flexion (controlled active motion) is similar. Mobilisation exactly as for primary repairs is a convenient unit policy.

When two-stage grafting is used, the old tendons are removed at the first operation. The proximal FDS or FDP motor tendon is held to physiological length by suturing it, with a non-absorbable 2/0 or 3/0 suture, to either the deep transverse ligament in the palm or the ligamentous structures of the flexor aspect of the wrist. Our own preference is for a proximal profundus-graft junction in the palm as this requires a shorter graft and we have only rarely seen the intrinsic plus phenomenon. We have only limited experience of the Paneva-Holevich technique of suturing the distal end of the proximal FDS to the distal end of the profundus tendon in the palm at the first operation and see no particular advantage to this technique. The proximal FDS is not our first choice as a graft as it can be slightly thickened and a little tight within the flexor sheath and most of the few cases in which the senior author has used this procedure have healed this tendon connection with considerable inflammatory swelling which required tenolysis (just where all of the flexor tendons enter the narrow carpal tunnel) with paring down of the bulk of the junction. A silicone rod of approximately the diameter of one of the patient's flexor tendons is placed between the proximal motor and the distal phalanx. These rods are manufactured in round and oval shape: Either works equally well. We use sizes 3 or 4 most commonly. The distal end of the rod is cut obliquely and passed behind the FDP stump distally, to maintain a pocket, then sutured to the FDP stump. It is passed proximally through the tendon sheath to the palm or the wrist. The free proximal end of the rod is not sutured and should reach slightly proximal to the sutured end of the motor tendon in the palm or wrist. The hand is closed and mobilised fully until completely supple, then the tendon grafting procedure is carried out. Usually between three and five months is an adequate delay. Impatience to complete the second stage in the surgeon or the patient is counterproductive as the final result is generally much better if the healing process of the first, and larger, operation is completely over. At the second operation, it is only necessary to expose the rod at its two ends to allow attachment of the graft distally and proximally as described above for one-stage grafting. The first stage of a staged tendon graft procedure requires no protection post-operatively and the patient usually returns to work within 2 to 3 weeks. After the second stage, the graft must be protected as for a primary repair or single-stage grafting. As the second stage can be carried out at any time after the hand has become supple, the patient has a wide choice of the timing of the second operation. This, and the fact that the second stage is inevitably being planned with a minimum of 3 to 4 months notice, is often convenient to the work situation. However, two-stage surgery can be unrealistic to the economic needs of many patients in many parts of the world and pragmatism in this respect is probably the major determinant of the preferences of different surgeons for single or two-stage grafting!

A major advantage of the two-stage management of the tendon is that all reconstitution of the skin and/or the pulleys can be carried out at the first stage when these will not be compromised by post-operative management considerations intended to protect a repaired flexor tendon system (see later).

BOW-STRINGING AND PULLEY RECONSTRUCTION

Except after surgical intervention, clinically obvious bow-stringing virtually only occurs in the proximal finger and thumb [Figure 3] and requires that the finger A2 pulley or the thumb A1 and oblique pulleys are not functional but at least one flexor tendon is intact. This is an unusual problem, probably because a lacerating injury which is longitudinal, or oblique enough, to cut these pulleys while leaving at least one flexor tendon intact is unusual. Occasionally, a severe crush injury of the finger with bursting lacerations of the skin, and usually a badly comminuted proximal phalanx, will include rupture of the A2 pulley. Occasionally, A2 division is a result of bad previous surgery [Figure 4]. Sometimes, the destruction of the A2 pulley in the initial injury may only become obvious during the process of freeing badly scarred flexor tendons at tenolysis. Sometimes, this process can result in inadvertent destruction of the pulley.

Figure 3

Clinical bow-stringing of the thumb as a result of the primary injury in a patient presenting for the first time for surgery

Figure 4

Absence of the A2 pulley in a patient referred with bow-stringing three years after primary flexor tendon surgery to this finger

Occasionally, when a patient has clinically obvious bow-stringing, he, or she, may not request reconstruction as objects being gripped in the hand will flatten the tendons back against the digit. The treatment of proximal bow-stringing in the presence of one, or two, intact flexors demands a pulley reconstruction which is strong, so that mobilisation can start immediately. Probably the commonest reconstruction used currently is that in which a strong tissue such as the extensor retinaculum (Lister, 1979),[19] or the palmaris tendon, is passed round the bone and sutured to itself [Figure 5]. Bearing in mind the problem of extensor tethering mentioned earlier, there must be some reservations on theoretical grounds about this technique. It may be preferable in this respect to suture the new pulley to the sides of the phalanx and avoid invading the extensor space. However, conventional suturing is not strong enough to take immediate loading by early mobilisation. Perhaps, mini bone tags may achieve this strength in such a pulley reconstruction, but we have not yet tried this.

Figure 5

Replacement of the A1 and oblique pulleys of the thumb of the patient illustrated in Fig 3 with a palmaris longus tendon wrapped around the skeleton of the thumb and passing under the extensor tendon

We, much more commonly, have a need for pulley reconstruction when we explore a flexor secondarily and come across severe scarring [Figure 6]. The A2 pulley may have been destroyed in the original injury, or is nonexistent by the end of the tenolysis, as freeing the tendon(s) under the intact pulleys is the most difficult part of this difficult procedure. Where the potential for bow-stringing arises after flexor tenolysis surgery, pulley reconstruction should be carried out. This has to be strong immediately, as for clinical bowstringing, if the tendons remain intact, or a policy decision is made to graft in a single stage. It is more simple to reconstruct a new pulley at the first stage of a two-stage tendon graft when the missing A2 pulley can be replaced without having to take the strain of the functioning tendons immediately. Fortunately, it is usually the case that A2 pulley reconstruction is being carried out in combination with tendon reconstruction, so it is possible to choose to reconstruct the tendon in two stages. A length of the tendons being removed from the finger, or, if these are too poor, the more proximal part of the one which will not be used later as the motor for the graft, can be used as material to reconstruct the pulleys at the first stage [Figure 7]. The tendon, split longitudinally and turned through ninety degrees, will provide enough material to make as many pulleys as required [Figure 8]. Because there will be no force on the reconstructed pulleys, they can simply be sutured to the remnant edges of the sheath, over a silicone rod. They will be strongly bound by the time they have to withstand a mobilising tendon in 3 to 6 months. It is possible to reconstruct a considerable length of the tendon sheath by this technique and we routinely replace as much of the A2, C1, A3, C2 and A4 pulleys as are badly scarred, flimsy or absent. This technique also avoids the use of extensor retinaculum to make pulleys, as harvesting this tissue leaves an obvious scar on the very visible dorsum of the wrist.

Figure 6

Severely scarred flexor tendons and sheath with considerable likelihood of tenolysis ending without an intact A2 pulley and with the tendons severely frayed or divided

Figure 7

After tenolysis, the flexor tendons have been replaced by a silicone rod. The redundant superficialis tendon proximal to the finger may be excised, split longitudinally and used for reconstruction of pulleys over the rod (see also Fig 8)

Figure 8

Reconstruction of multiple pulleys over a rod with material harvested from discarded flexor tendon as in the previous figure

Where isolated loss of the A4 pulley has occurred, for whatever reason, and most of the remainder of the sheath remains intact, function is unlikely to be affected. Bow-stringing at the distal joint in isolation is a clinical situation which the authors have never seen and the potential for this to occur on flexion of the joint, even when not gripping an object and forcing the tendon back against the skeleton, is small as the distal joint flexes too little and the length of free tendon is too short. For distal bowstringing to occur requires that the whole length of the sheath distal to the A2 pulley be missing [Figure 9], which happens most commonly because we start all secondary flexor surgery in the finger by opening the sheath through the A3 and C pulleys and usually destroying them in the process. Then, either an already disrupted A4 pulley is revealed or this pulley is disrupted during the dissection to free the tendon under it. The problem of distal bowstringing can largely be avoided by also preserving part of the A3 pulley [Figure 1] whenever possible at the start of dissection and, secondly, by replacing the A4 pulley when necessary. Where all of the sheath has been removed distal to the distal edge of the A2 pulley and distal bow-stringing is anticipated. It can often be replaced with local tissue from discarded tendon as described above. We would question the wisdom of the suggested technique of A4 pulley reconstruction by passing a segment of palmaris or plantar is tendon around the middle phalanx then superficial to the extensor tendon. The space around the extensor tendon over the middle phalanx is so small as to make extensor tethering with loss of DIP flexion almost inevitable. Over and above the space occupation by such a pulley reconstruction and the scarring, if it were sufficiently tight to function as a pulley it would be unlikely to allow movement of the extensor tendon. A tenodesis of this tendon, with loss of distal joint flexion, would seem inevitable. Fortunately, the need to carry out this reconstruction in isolation is more hypothetical than real.

Figure 9

Distal bow-stringing beyond the distal edge of the A2 pulley in the absence of the C1, A3, C2 and A4 pulleys

AVOIDING SECONDARY SURGERY

Although we can achieve flexor function by secondary surgical techniques, it is important to realise that, whatever problems we have after primary surgery and good therapy, the results are much better overall than those of secondary surgery. Secondary surgery of the flexor tendons remains difficult, with, often, poor results.

Although we have to do secondary procedures, sometimes we can avoid them. Probably the major determinant of whether more, or less, divided flexor tendons are repaired primarily in any location is the local medico-political situation. It is beholden on senior hand surgeons to involve themselves in the battle for more hand surgical availability — more surgeons, therapists and facilities — and for arrangement and education of the emergency services to allow these injuries to be relocated to appropriately trained surgeons and hand therapists. Extending delayed primary repair and re-repair of ruptured primary repairs, both discussed earlier, may avoid secondary surgery. Because the patient is a major risk factor in this process, he cannot be a passenger. He must understand the difficulties: A move from the top of the fence on which he is walking is a disaster waiting to happen. Too much movement and the repair snaps, too little and it sticks. If either happens, salvage surgery — which is what secondary flexor tendon surgery is in these circumstances — will mostly end up with a worse result.

Knowledge of technical tricks may also allow us to avoid secondary surgery. Le Viet intramuscular lengthening of the proximal tendon has been discussed and may avoid grafting a divided long flexor tendon of the thumb particularly. This technique can occasionally be useful to overcome the same problem of muscle retraction after late presentation of divisions or pull-off of the finger flexors. Secondary surgery can also, sometimes, be avoided using this technique in cases presenting with small segments of tendon missing. The advantage of repairing only the FDP tendon in certain severe injuries in Zone 2C and Zone 4 in order to avoid secondary surgery has also been discussed. Secondary surgery can be avoided in cases in which an FDP pull-off presents late with the FDP too swollen to pass under the A4 pulley, by halving the distal part of the FDP tendon and passing one-half of the tendon through the pulley to reattach it (Elliot et al, 2001).[20] The double-barrelled nature of the distal part of the FDP lends itself to this manoeuvre. As the palmaris tendon is routinely less than half the diameter of the FDP, half of the FDP should be stronger than a palmaris graft. It is also much easier to insert a Kessler suture into the half FDP than into the palmaris, or plantaris, tendon.

There are several situations when we should not carry out secondary surgery. One can categorise these cases broadly into unsuitable patients and unsuitable hands. Where cases presenting for secondary surgery are failures of primary surgery, our therapists know these patients and can tell us if the patient is unlikely to achieve anything from further surgery. Thus, unsuitable patients can be weeded out before embarking on something which is beyond their capabilities of co-operation. Occasionally, patients present with specific clinical situations which are unsuitable for secondary flexor tendon grafting. An example of this is the long-standing injury of the index finger which is being bypassed. Thumb pinching to the middle finger has been established at a cerebral level and there is little possibility of a secondary flexor tendon reconstruction achieving a pinching index finger, although the finger may contribute to power gripping after restoration of flexion activity.

SIMPLIFYING SECONDARY SURGERY

Where secondary surgery is necessary, many techniques which simplify the surgery have already been discussed, e.g. distal FDP tenodesis when the FDS is intact instead of trying to re-establish FDP function, attachment of the detached FDP and tendon grafts to the distal phalanx without a button, pulley reconstruction over a tendon rod at the first stage of a two-stage procedure and standardising rehabilitation when mobilising primary flexor repairs, flexor tendon grafts, tenolyses, flexor tendon transfers and replantations/revascularisations.

CONCLUSION

Primary flexor tendon surgery has advanced a long way in the last 50 years. By contrast, secondary surgery has changed little in this time and remains difficult technical surgery, after which it is difficult to achieve good results. As the number of patients having secondary surgery gets less, our expertise may also be diminishing. Perhaps, also, the fact that we are still using many of the same surgical techniques used in the 1950s to deal with these bad injuries and bad patients may be contributing to our results getting no better.

We would like to finish with a caveat. In this era, there can be few cases in which amputation, either within the finger or as a ray amputation, is justified for flexor tendon dysfunction. Apart from the cosmetic implication and the grip loss of even a single finger amputation, formation of a single end-neuroma of one of the divided digital nerves can render a hand which was a nuisance completely functionless and, sometimes, destroy the patient's life. This chapter has been a resumé of conventional secondary flexor tendon surgery. Over and above the considerable possibilities of such surgery, we should be looking for such new alternatives as the vascularised transfer of the flexor tendon with its gliding bed from the distal forearm to the digits which has been so beautifully demonstrated and performed clinically in many severely scarred cases by Jean-Claude Guimberteau of France to avoid amputation (Guimberteau, 2001).[21]