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Keys To Revising Failed Flatfoot Surgery
Given the la
ck of consensus on indications and procedures for flatfoot surgery, these authors offer their insights on revisional flatfoot surgery. In addition to discussing diagnostic keys and pearls on appropriate procedure selection, they share their clinical experience in revising both overcorrected and undercorrected flatfoot as well as correcting nonunions.
Researchers originally described flexible flatfoot or adult-acquired flatfoot deformity as a foot that is structurally stable and flattens with weightbearing stress.1 Prior work by Harris and Beath found that a flexible deformity is present 64 percent of the time in the adult flatfoot population.1 In their study, equinus/relative shortening of the Achilles tendon had a role in causing pain and disability in 27 percent of the study population.
Typically, a patient’s foot functions optimally through the gait cycle when the foot maintains appropriate muscle tendon balance coupled with the static structure of the foot. Based on electromyography findings, Basmajian and Stecko originally postulated alterations in the optimal position and function of the posterior tibial tendon as major factors in flatfoot deformity.2
Posterior tibial tendonitis dysfunction (PTTD) is a process that is usually on a continuum. Tenosynovitis progresses to further tendon degeneration, which leads to a change in tendon morphology and subsequently leads to further dysfunction. When the tendon becomes misshapen, the tendon becomes weaker. The midfoot/hindfoot joints collapse and eventually progress to a more rigid, fixed flatfoot deformity with ankle valgus in its most advanced stages. Only approximately 50 percent of individuals report a history of trauma.3 Patients can expect pain, fatigue, joint degeneration and associated deformities such as hallux valgus, hammertoes and metatarsalgia with long-term pathology.4
Currently, there are no universally accepted clinical or radiographic definitions of the average height or the normal range of heights of the longitudinal arch. Recent work by the senior author and colleagues has been able to establish normal radiographic values of the pedal architecture to aid the clinician in successful correction of pes planovalgus deformity. 
The goals of conservative management often entail the reduction of clinical symptoms and prevention of flatfoot progression with the use of non-steroidal anti-inflammatory medications (NSAIDs), ankle foot orthoses (AFOs), other devices such as the University of California Berkeley Labs (UCBL) orthosis, and conventional orthotics with associated hindfoot/forefoot accommodation as indicated. One may treat acute tenosynovitis with success utilizing a short walking cast or removable cast boot.5 Historically, gastrocnemius–soleus complex stretching exercises have been helpful with early stage posterior tibial tendonitis and the prevention of precipitating pes planovalgus deformity.6
Currently, there is little agreement on indications for surgery and which procedures surgeons should perform based on clinical findings. There are many classification systems to help guide the clinician with some objectivity. According to Johnson and Strom, in stage 1, the tendon length is normal with mild degeneration present and clinically medial foot pain is present.7 In stage 2, the most common stage, the tendon becomes functionally incompetent and the single heel raise test is positive with a “too many toes sign” visible. In stage 3, a fixed hindfoot deformity develops with possible abutment of the lateral subtalar joint. Finally, Myerson and Bluman popularized stage 4 with valgus tilt of the talus present within the ankle mortise.8
Essential Insights On Diagnostic Imaging
Radiographs. It is paramount to obtain the appropriate radiographs and perform an accurate clinical exam for successful initial and revisional surgical intervention. Key radiographic parameters include the anteroposterior (AP) and lateral talar first metatarsal angle (Meary’s), AP cuboid abduction angle, AP and lateral talocalcaneal angle, lateral metatarsal declination, AP talonavicular uncovering and the hindfoot axial alignment view of bilateral tibial calcaneal relationships. Researchers have shown the hindfoot axial alignment view (Saltzman) correlates well with clinical resting calcaneal stance position (RCSP).9 
In addition to pes planovalgus deformity assessment, one can evaluate degenerative joint changes and tarsal coalitions to assist in surgical decision making (i.e. anterior osteophyte resection for equinus deformity and coalition resection versus obtaining further advanced imaging respectively). Lastly, we recommend obtaining a static AP view of the entire lower extremity to establish if any proximal deformity is present. It is our experience that if the ankle/subtalar joint (hindfoot) complex is supple, then proximal deformity will influence pedal architecture. However, with longstanding deformity and associated rigid hindfoot deformity, the knee alignment will be affected by the pedal position.
Magnetic resonance imaging (MRI). Conti and colleagues developed a classification scheme for tears of the posterior tibial tendon based on MRI.10 The classification takes into account structural features and abnormal signals within the substance of the tendon. In a type 1 tear, the MRI shows one or two fine, longitudinal splits in the tendon. The T1 weighted images reveal a homogeneous black signal throughout the tendon. Type 2 tears are characterized by wider longitudinal tendon splits and intramural degeneration with gray areas on T1 weighted images within the tendon and bulbous sections visible. Type 3 tears are notable for more diffuse swelling and uniform degeneration of the tendon with scar tissue present. Finally, complete tendon rupture would be visible with this modality. 
In addition, our practice has found it quite useful to incorporate this imaging modality in the diagnosis of newly symptomatic fibrous coalitions, with or without precipitating trauma, as well as locating areas of symptomatic geographic subchondral cysts, particularly in cases of subfibular impingement. One can visualize further anatomic differentiation of soft tissue derangement including assessing the spring ligament complex as well as lateral ligamentous pathology. Generally, we will obtain MRI without contrast to evaluate musculoskeletal abnormalities. However, medial arch pain should also prompt a thorough evaluation for musculoskeletal or vascular tumors.
Computed tomography (CT). The role of CT scans of the lower extremity in assessing pes planovalgus deformity is rather limited with the exception of coalition identification, cortical detail of subchondral cyst formation and gaining greater detail of adjacent joint degenerative changes. With respect to revision surgery, CT has been instrumental in the evaluation of hardware failure and nonunion after arthrodesis and extra-articular osteotomies.
Pertinent Perspectives On Procedure Selection
Various procedures are available to correct pes planovalgus deformity. Options include medial soft tissue plication (to include the posterior tibial tendon, medial capsule and/or spring ligament), tendon transfers (posterior tibial tendon advancement, flexor digitorum longus transfer, tibialis anterior transposition), gastrocnemius recession, tendon Achilles lengthening and peroneus brevis lengthening. One can perform these procedures in isolation yet they are far more effective and provide greater longevity when one combines them with adjunctive structural interventions such as arthrodesis or extra-articular osteotomies. Researchers have demonstrated that osseous excision with interposition is a viable option if an osseous/fibrocartilaginous coalition is present.11,12
Typically, the finding of a stage 2 PTTD drives surgical decision-making. For mild cases, the classic recommendations are to debride the tendon/repair the tendon with advancement onto the navicular and depending on the degree of clinical attenuation, tenodese or transfer the flexor digitorum longus (FDL). Despite documented FDL hypertrophy in 27 percent of patients and posterior tibial tendon hypertrophy in 23 percent, frequently authors recommend a medial displacement calcaneal osteotomy.13 Studies support this protocol for the surgical management of PTTD/adult-acquired flatfoot with 97 percent significant pain relief and 92 percent entirely satisfied with the procedure in 129 patients at a mean follow-up of 5.2 years.13 
It is our belief that many cases of posterior tibial tendonitis are different and varying structural compromise exists across a population. Therefore, one should undertake a systematic approach with the correction of structural influences should they exist prior to soft tissue correction/augmentation. Commonly, a prominent os tibiale externum (accessory navicular) may be present. If this is symptomatic, it would be conceivable to excise and advance the tibialis posterior tendon. However, surgeons should exercise caution when performing this procedure in isolation as biomechanical instability could be present at the level of the calcaneus or midtarsal joint complex.
Commonly, the treatment for advanced adult-acquired flatfoot deformity has been the triple arthrodesis (originally described by Ryerson in 1923 for neuromuscular associated deformity) or double arthrodesis (excluding the calcaneocubioid joint).14 Arthrodesis of the talonavicular joint, STJ and/or calcaneocuboid joint often causes a loss of shock absorption and potential degenerative joint disease to adjacent joints such as the ankle and naviculocuneiform joint.
Astion and colleagues were able to demonstrate 91 percent restriction of the STJ and 75 percent restriction of posterior tibial tendon excursion/motion following simulated talonavicular joint arthrodesis in a cadaveric model. In contrast, STJ simulated arthrodesis restricted talonavicular joint motion by 74 percent with a 54 percent loss of posterior tibial tendon excursion.15 Interestingly, authors have shown ankle valgus to be precipitated approximately threefold with triple arthrodesis in comparison to double arthrodesis.16
In our practice, it has not been uncommon to detect lateral ankle instability intraoperatively secondary to longstanding ankle valgus deformity. In addition, subfibular impingement after triple arthrodesis may necessitate a posterior calcaneal realignment osteotomy. Classically, the patient will present to the office setting complaining of persistent lateral ankle pain, which one presumes the index procedure already addressed. 
Further, it is important to assess the center of rotation of angulation (CORA) of the deformity both preoperatively and intraoperatively in an effort to determine the precise location of deformity, such as in the case of forefoot supinatus or naviculocuneiform breach. One can accomplish this by evaluating the reference lines drawn according to radiograph normative values and analyzing where they intersect. Limited medial midtarsal fusions at the incorrect joint offer incomplete deformity correction and a higher likelihood of recurrence and compensatory adjacent degenerative joint disease.
Revising Overcorrected And Undercorrected Flatfoot
The Dwyer calcaneal wedge osteotomy is an effective procedure. With appropriate preoperative planning, one can use this procedure to correct hindfoot frontal plane resting calcaneal stance position through an extra-articular calcaneal osteotomy. In addition, in order to achieve 5 to 10 mm of lateral translation of the calcaneal tuber relative to the tibial anatomic bisection, surgeons can often combine this procedure with a posterior calcaneal slide/displacement osteotomy (Koutsogiannis procedure). In revision cases, these procedures have been useful in addressing overcorrected pes planovalgus reconstruction as well as malaligned triple arthrodesis.
In regard to the undercorrected flatfoot, lateral calcaneal lengthening, although it structurally corrects transverse plane deformity, may help restore the function of the STJ complex through its effects on adjacent soft tissue structures.18,19 These effects include utilization of the talonavicular joint as a fulcrum, tightening of the plantar fascia and effective shortening of the peroneus longus tendon.
Clinically, researchers have described long-term success of correction with the Evans calcaneal osteotomy and deemed it one of the most “powerful” procedures for symptomatic flat feet.18,19 Mild controversy exists regarding the amount of graft to use as this could cause increased calcaneocuboid joint pressures and an increase in lateral column overload with as little as a 2 mm incremental increase in graft size.20,21 However, we have yet to observe these changes clinically or radiographically. Authors have reported significant improvements in radiographic parameters, including improvements in the talo-first metatarsal angle from 21°±9.6° to 6.3°±7.4°, the calcaneocuboid angle from 28.3°±9.0° to 12.3°±6.1°, the calcaneal inclination angle from 13.8°±5.7° to 21.3°±7.7° and the tibial-calcaneal angle from 15.3°±8.2° to 2.2°±3.6°.22 The mean graft size was 12.2±1.3 mm and allowed for medialization of the calcaneal tuber of 0.8 mm.22 
Further, the use of autograft versus allograft has had debate as autograft harvest has been associated with significant postoperative morbidity.23 In a multicenter trial of 300 foot and ankle procedures with 126 calcaneal allografts, Mahan and Hillstrom demonstrated no significant differences in comparison to autograft for foot and ankle surgery.24 In their observational study of 49 patients (51 feet), Grier and colleagues demonstrated successful union rates of 70 percent in the autograft group in comparison with 94 percent of feet in the allograft group.25 We should note that Grier and colleagues used adjunctive platelet rich plasma injection (PRP) for the allograft procedures as this may have influenced their results.
The use of fixation with this type of osteotomy remains under debate with dorsal displacement of the anterior process being a common consequence of this procedure. Dunn and colleagues reviewed 50 procedures with a mean dorsal displacement of 1.21 mm at the six-week follow-up yet this reduced to a mean of 0.57 mm at a mean 30-week follow-up.26 Further, radiographic improvement remained with respect to decreased talar declination and increased calcaneal inclination. No patients required a return to the operating room nor did they experience any postoperative complications.
Addressing Nonunion Repair
Large graft sizes do theoretically increase the incorporation times and thus increase the chance of union or partial union. We will use larger graft sizes of 10 to 15 mm in order to completely correct the flatfoot osseous deformity. The goal is a vertical heel as measured by an axial calcaneal radiograph, which includes the tibia (hindfoot alignment view). Revision of a calcaneal Evans graft nonunion is rare but requires aggressive treatment once one has detected a nonunion with a CT scan. Treatment of calcaneal nonunions includes curettage/drilling, bone marrow aspirate augmentation, bone grafting, removal and replacement of graft, the utilization of an autograft, and the application of stable internal or external fixation.
Notable pearls with this procedure include assessing the hindfoot axial alignment prior to performing this intervention and establishing the role of the midtarsal pronation in an effort to prevent overcorrection. Other pearls include avoidance of the superficial peroneal nerve and sural nerve communicating branches; creating the osteotomy in a slight anterior orientation to avoid the middle facet of the talus; ensuring competence of the plantar fascia; creating a trapezoidal structural graft with placement against a rigid cortical substrate to prevent subsidence (dorsal lateral calcaneus); performing a stepwise inspection of the foot in all planes under fluoroscopic guidance; and performing adjunctive procedures when necessary. It is important to inspect hindfoot valgus, forefoot varus/supination and for the presence of equinus deformity.
Authors have also proposed a combination procedure in the form of a double calcaneal osteotomy (posterior calcaneal displacement osteotomy in conjunction with lateral column lengthening) as a means of correcting hindfoot valgus and lateral translation of the calcaneal tuber with restoration of tibial calcaneal alignment.27,28 A recent study by Basioni and colleagues evaluated 14 patients (17 feet) with improvement in the mean AOFAS score of 48.4±15.1 to 78.6±6.7 following single lateral incision double calcaneal osteotomy and adjunctive tendon Achilles lengthening (TAL) at a six-month follow-up.29 
In large flatfoot deformity cases, we feel that a double calcaneal osteotomy may be necessary to correct the hindfoot valgus. Surgeons should reserve this for the cases in which both an Evans and a medial soft tissue plication cannot fully correct the flatfoot.
Following hindfoot correction, when residual forefoot supination or varus is present (in the case of revision or adjunctive surgery), one may need to perform a medial column stabilization procedure.30,31 We employ two different corrections based on an osseous or soft tissue etiology of the forefoot deformity. When an osseous deformity is present, one can correct this with either a closing wedge based plantar or opening wedge based dorsal osteotomy at the apex/center of rotation of angulation, which typically corresponds to the medial cuneiform. When a soft tissue imbalance is present, one can perform a peroneus brevis tendon lengthening or a peroneus longus tendon shortening.
In Summary
Surgical reconstruction of flatfoot requires a careful systematic approach including the appropriate use of radiographs and correlation with the clinical exam. Revision surgery should focus on anatomic and functional restoration. We do not present algorithms but principles that provide acute reference points in order for surgeons to develop a sound plan. It is imperative to develop a thorough understanding of each individual patient’s problem in order to accurately diagnose the problem. The revision surgery may require undoing what already happened and then performing the corrective procedure(s).
Dr. Wynes is a staff foot and ankle surgeon in the Department of Orthopaedics at the University of Maryland Medical Center. He is an Associate of the American College of Foot and Ankle Surgeons.
Dr. Lamm is the Head of Foot and Ankle Surgery at the International Center for Limb Lengthening, and Director of the Foot and Ankle Deformity Correction Fellowship at the Rubin Institute for Advanced Orthopedics at the Sinai Hospital in Baltimore. He is the Rotation Director for the Podiatric Residency at Harvard Medical School. Dr. Lamm is a Fellow of the American College of Foot and Ankle Surgeons. He also is a section editor for the Journal of Foot and Ankle Surgery and serves on the PRESENT Podiatry Advisory Board.
References
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17. Lamm BM, Gesheff MG, Salton HL, Dupuis TW, Zeni F. Preoperative planning and intraoperative technique for accurate realignment of the Dwyer calcaneal osteotomy. J Foot Ankle Surg. 2012;51(6):743-8.
18. Phillips GE. A review of elongation of os calcis for flat feet. J Bone Joint Surg. 1983;65B:15-18.
19. Bolt PM, Coy S, Toolan BC. A comparison of lateral column lengthening and medial translational osteotomy of the calcaneus for the reconstruction of adult acquired flatfoot. Foot Ankle Int. 2007;28(11):1115-23.
20. Ellis SJ, Williams BR, Garg R, Campbell G, Pavlov H, Deland JT. Incidence of plantar lateral foot pain before and after the use of trial metal wedges in lateral column lengthening. Foot Ankle Int. 2011;32(7):665-73.
21. Oh I, Imhauser C, Choi D, Williams B, Ellis S, Deland J. Sensitivity of plantar pressure and talonavicular alignment to lateral column lengthening in flatfoot reconstruction. J Bone Joint Surg Am. 2013;95(12):1094-100.
22. Siddiqui NA, Lamm BM. Digital Planning for Foot and Ankle Deformity Correction: Evans Osteotomy. J Foot Ankle Surg. 2014, Epub ahead of print.
23. Pirris SM, Nottmeier EW, Kimes S, et al. A retrospective study of iliac crest bone grafting techniques with allograft reconstruction: do patients even know which iliac crest was harvested? J Neurosurg Spine. 2014; 11:1-6. [Epub ahead of print]
24. Mahan KT, Hillstrom HJ. Bone grafting in foot and ankle surgery. A review of 300 cases. J Am Podiatr Med Assoc. 1998;88(3):109-18.
25. Grier KM, Walling AK. The use of tricortical autograft versus allograft in lateral column lengthening for adult acquired flatfoot deformity: an analysis of union rates and complications. Foot Ankle Int. 2010;31(9):760-9.
26. Dunn SP, Meyer J. Displacement of the anterior process of the calcaneus after Evans calcaneal osteotomy. J Foot Ankle Surg. 2011;50(4):402-6.
27. Frankel JP, Turf RM, Kuzmicki LM. Double calcaneal osteotomy in the treatment of posterior tibial tendon dysfunction. J Foot Ankle Surg. 1995;34(3):254-61.
28. Catanzariti AR, Mendicino RW, King GL, Neerings B. Double calcaneal osteotomy: realignment considerations in eight patients. J Am Podiatr Med Assoc. 2005;95(1):53-9.
29. Basioni Y, El-Ganainy AR, El-Hawary A. Double calcaneal osteotomy and percutaneous tenoplasty for adequate arch restoration in adult flexible flat foot. Int Orthop. 2011;35(1):47-51.
30. Ling JS, Ross KA, Hannon CP, Egan C, Smyth NA, Hogan MV, Kennedy JG. A plantar closing wedge osteotomy of the medial cuneiform for residual forefoot supination in flatfoot reconstruction. Foot Ankle Int. 2013;34(9):1221-6.
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For further reading, see “Current Concepts In Surgery For Adult-Acquired Flatfoot” in the October 2012 issue of Podiatry Today.
