The most commonly ruptured tendon in the foot and ankle region is the Achilles tendon (AT) with tibialis anterior being the second most common sustaining complete ruptures. Although nonoperative management of AT ruptures can yield good results, acute end-to-end repairs are frequently performed. Failure of repair will require revision surgery, often using advanced reconstructive techniques. Tibialis anterior ruptures are uncommon, very often missed, and patients usually present with chronic ruptures. Thus, even primary surgery, when indicated, is rare and may be complex (eg, using tendon auto- or allografts) and revision surgery even less common and more challenging. The peroneal tendons are, probably, more frequently injured as a result of ankle inversion sprains; however, these injuries result in longitudinal tears, rather than complete ruptures. If tibialis posterior tendon is found completely ruptured, this is usually a result of chronic tendinopathy and/or degeneration, associated with pes planovalgus foot deformity. Thus, repair in the acute or chronic state is not indicated and management of the ruptured or reruptured tibialis posterior tendon is part of pes planovalgus foot reconstruction.
Finally, ruptures of flexor tendons in the foot (FHL, flexor hallucis longus; FDL, flexor digitorum longus) are rare, often iatrogenic, or a result of high-energy ankle and/or hindfoot fracture-dislocations. When identified, those are primarily repaired, and revision repair is usually not necessary. Furthermore, late FHL or FDL reconstructions are not indicated or recommended, as the potential benefits are not outweighed by the associated morbidity, considering that that FHL and FDL are often used as donor tendons in tendon transfers for other tendon pathologies.
In this chapter, we will present surgical techniques for repair and reconstruction of previous failed surgery for the AT since other tendinous pathology is covered in the text.
Achilles Tendon Ruptures
The reported incidence of AT injuries is 18 ruptures per 100,000 people.1,2 In recent years, nonoperative management of the primary rupture has gained in popularity. Studies have shown that, with an accelerated rehabilitation protocol (allowing early weight-bearing and functional rehabilitation), functional outcomes of nonoperative management are as good as those of surgical repair.3,4 However, it is debated that surgical primary repair may be indicated for young, more active, and athletic patients. Also, given that ruptures of the AT are often “missed” initially, and/or patients may seek medical assessment several days to weeks after the injury, surgery may be the only way forward for these patients, to approximate tendon stumps and restore length and tension of the ruptured tendon. Usually end-to-end repair, even by means of less invasive surgery, is possible even at 4 weeks after the injury.5
The most common complications following operative management include rerupture, wound breakdown, and deep infection.6 Rerupture rates after surgical primary repair range between 2% and 8%.7–10 In a large cohort of 409 patients undergoing primary repair of a ruptured Achilles the incidence of deep infection was 2.2%,9 whereas wound healing problems after open primary repair have been reported to be as high as 20%.1 These can lead to devastating problems, and reconstruction is essential to allow patients to return to normal daily life activities and their jobs, as well as to resume sports activities. Following these complications, the treating surgeon has to consider reconstruction options that are a lot more invasive and technically demanding compared with primary repair.
In the presence of infection following primary repair, extensive debridement to healthy tissue is required, and this often generates a large gap between proximal and distal stumps of the AT.9 One has to take into consideration the condition of the skin that also requires debridement, leaving a skin defect requiring coverage. In such cases, plastic surgeon’s intervention is necessary as local or free tissue transfer may be required. Rerupture, without infection, is also a devastating complication, difficult to manage. The tendon will be elongated, with scar tissue formation bridging the stumps, and debridement will lead to a gap that needs bridging. Thus, it is unlikely that secondary end-to-end repair can be possible or recommended. Furthermore, the vascularity of the region, especially after open primary repair will be suboptimal and turns revision repair into a higher risk procedure regarding failure (delayed healing, possible tendon elongation, rerupture, or infection). This could lead to an unsatisfactory clinical outcome.7
Other surgical reconstruction options include V-Y tendon flap; augmentation and tendon transfers using peroneus longus, peroneus brevis, FDL, FHL, hamstrings tendons, plantaris, and fascia lata; allografts; and synthetic grafts.2,7,11
Tendon transfers are obviously associated with added morbidity, related to donor tendon harvesting. Furthermore, sacrificing the transferred tendon can affect foot and ankle biomechanics. At the same time, one has to bear in mind the naturally low blood supply of the AT that results to a reduced healing potential.12 This is important when considering avascular grafts (eg, synthetic and allografts and also free tendon transfers from other parts of the extremity, like the hamstrings). Although use of allografts and synthetic grafts does not cause any morbidity associated with harvesting, it is questionable whether their use is appropriate in the unfavorable environment, regarding vascularity, around the AT, especially in the presence of previous failed surgery and scar tissue formation. Their use is definitely not recommended in the presence of infection.
In order to maximize the effect/strength of the tendon transfer, the donor tendon should, ideally, function in phase with the ruptured tendon.13 FHL tendon is the one fulfilling this requirement as has been extensively used and, according to many surgeons, it can be considered the current “gold standard.” It is a strong plantarflexor, its muscle belly extends into the avascular zone of the AT (providing new blood supply to the repaired AT), and its use does not seem to affect the muscle balance around the ankle.2 However, its harvesting is associated with dynamic reduction in big toe plantarflexion power, which is essential for higher-impact physical exercise.15
Therefore, other options have also been sought and several recent reports exist that discuss the potential benefit of using a semitendinosus autograft, in isolation, to reconstruct chronic AT ruptures14 or acute insertional ruptures,15 while other options include the use of both semitendinosus and gracilis16 or peroneal tendons as autografts.15
The ability to perform a direct end-to-end repair in revision surgery of AT is very challenging owing to the large gap that is generated after scar tissue debridement and proximal stump retraction. Direct repair is only advocated in the presence of gaps less than 2 cm after thorough debridement. This, however, is very uncommon. Another option to bridging gaps between 2 to 5 cm is to perform a less aggressive debridement of the interposed scar tissue and use this tissue to help with tendon stump apposition.17,18 Few studies have shown good functional results with this technique, but there are reservations that the interposed scar tissue is of inadequate strength, while elongation of the myotendinous unit after continuous loading of the repaired tendon occurs.
V-Y Achilles Tendon Advancement
This technique can be used to treat defects less than 5 cm.19 The V-Y lengthening is performed at the level of the proximal fascia, thus avoiding a cut into the muscle belly. Disadvantages of the technique are a large surgical scar due to the exposure and the potential weakness with plantarflexion secondary to lengthening of the myotendinous unit. This is the reason why most surgeons use FHL augmentation at the same time.20
Turn-Down Flap (Bosworth Procedure)
There are several, surgeon-dependent modifications of this technique. After debridement of the scar and/or infected tissue (Figure 17.1A-C), the gap is bridged using the central part of the healthy proximal tendon stump aponeurosis, which is rotated distally and sutured to the distal stump (Figure 17.1D and E). The proximal remnants of the aponeurosis can be repaired (Figure 17.1F).
In order to address the extra morbidity caused by autografts and the risk of disease transmission caused by allografts, synthetics were used to bridge gaps in AT repair. In the literature there have been studies that used different types of synthetic materials.24–26 Although most of them represent small case series and demonstrate satisfactory results, surgeons should consider that these materials have an increased risk of causing infection, wound problems, and an inflammatory response in an area with already reduced vascularity.27
Several soft tissue autografts have been used for AT reconstructions, usually following neglected ruptures, advanced tendinopathy, or failed previous surgeries. Fascia lata autograft has been used to reconstruct the AT defect in chronic ruptures. However, the literature consists mainly of very small case series or case reports.28 More recent studies have shown good results with the use of an anterolateral thigh free flap with vascularized fascia lata to reconstruct tendon defects when there is a concomitant skin defect.29 Hamstring tendons, gracilis, and/or semitendinosus have been used to autograft the repair.30,31 Gaps up to 9 cm were repaired with good functional outcomes in these studies. In the authors’ experience it is adequate and preferable to use only one of the tendons (gracilis or semitendinosus), to reduce donor site morbidity and preserve strength of the extremity.
Use of “local” donor tendons (peroneus brevis, FDL, or FHL) has the advantage of not adding morbidity to other parts of the extremity, while it also offers a vascularized tendon graft to perform the reruptured AT reconstruction. Considering that patients would have had previous surgery that has already disrupted the (relatively poor) peri-AT blood supply, use of a vascularized tendon graft may be biologically superior to other methods, enhancing healing potential and reducing infection risk.
The use of peroneus brevis as a transfer has been reported in various studies with good results.32–34 The characteristics that it shares with the AT are the plantarflexion and being in phase with it during gait cycle. It is, however, 18 times weaker than the AT. There are concerns for its use regarding reduced eversion of the ankle and the fact that anatomically it lies within a different muscle compartment.35 The proprioceptive role of peroneus brevis, contributing to dynamic ankle stability, might be another drawback in this technique.
Flexor Digitorum Longus
That FDL shares similar characteristics to peroneus brevis, like acting as plantarflexor and being in phase with the AT during gait, makes it a suitable tendon transfer. It has been used in recent studies with good results.36 However, it is even weaker than peroneus brevis and provides 27 times less power than the AT. Harvesting FDL can be associated with nerve or artery injury.37 In addition, there is a possibility of developing lesser toe deformities, as a result of imbalance between toes flexion and extension.
Flexor Hallucis Longus
FHL is often used as donor tendon when tendon transfers for AT problems are required.13 The main advantages include its proximity and the fact that it is “in phase” with the AT, the potential for hypertrophy, and the new blood supply that the FHL muscle belly offers to the relatively avascular area of the previous failed repair. FHL provides, thus, a vascularized graft, to bridge the gap and enhance the healing potential of the diseased AT. According to some authors, its muscle belly is much smaller than that of the gastrocnemius-soleus complex and 13 times weaker, and if used on its own (without attaching it to the proximal AT stump), the ultimate power patients can get will be reduced.13 In order for this to be avoided a “long FHL graft” is needed. This is possible if FHL is harvested distally in the plantar midfoot region and retracted proximally. However, this may increase morbidity (more invasive surgery, requiring dissection through deep layers of the foot and close to neurovascular structures), while harvesting of FHL can result in reduced hallux plantarflexion power, resulting in weakening of the “push-off” phase of gait. This may be a significant deficit for young athletic patients. This “side effect” could be diminished by harvesting a shorter FHL tendon graft, thus leaving the connections between the FHL and FDL tendons at the “knot of Henry” region intact.13