Pes Planus (Flatfoot) Treatment & Management
- Author: Matthew Buchanan, MD; Chief Editor: Anthony E Johnson, MD more...
Posterior tibial tendon (PTT) insufficiency with different degrees of deformity at different joints in the foot is a challenge to manage. Indications for treatment of PTT dysfunction include the following:
Difficulty with ambulation
A painless deformity that can be accommodated by normal footwear and allows for normal gait does not require treatment.
Considerable controversy remains about the appropriate treatment of all stages of PTT dysfunction. Therapeutic options take many forms, ranging from conservative management with the use of medication and orthotics to various surgical procedures.[55, 56, 57] Comparative outcome trials are needed to provide better data for evaluation of the various options. To the authors' knowledge, such trials have not yet been completed.
Operative treatment may involve the following:
Soft-tissue procedures alone
Soft-tissue procedures with the addition of an osteotomy
Contraindications to surgical intervention in adult-acquired flatfoot deformity (AAFD) are similar to those for any other foot or ankle surgery and include the following:
Active or chronic infection
Inadequately perfused foot
Otherwise, specific contraindications depend on the stage of the disease and an appropriate preoperative diagnosis. For example, performing a stage 1 procedure (ie, synovectomy) on a patient with stage 2 disease would most likely result in long-term postoperative failure. The same holds true for the other stages.
A flexor digitorum longus (FDL) transfer and calcaneal osteotomy would be contraindicated in a patient with fixed deformities or severe arthrosis of the hindfoot. A triple arthrodesis (fusion of the subtalar, talonavicular, and calcaneocuboid joints) alone or any lesser procedure would also be contraindicated in a patient with stage 4 disease. Proper diagnosis of the etiology and staging of disease are critical in the prevention of postoperative failure.
Medical or nonoperative therapy for PTT dysfunction involves the following[58, 59] :
Nonsteroidal anti-inflammatory drugs (NSAIDs)
Such therapy is especially attractive for patients who are elderly, who place low demands on the tendon, and who may have underlying medical problems that preclude operative intervention.
During stage 1 PTT dysfunction, the predominant manifestation is pain, rather than deformity. Cast immobilization (with NSAIDs if warranted) is indicated for patients with acute tenosynovitis of the PTT or for those whose main presenting feature is chronic pain along the tendon sheath. A well-molded short leg walking cast or removable cast boot should be used for 6-8 weeks. Despite the need for prolonged below-knee immobilization, chemoprophylaxis for venous thromboembolism (VTE) typically is not necessary unless three or more VTE risk factors are present.
Weightbearing is permitted if the patient is able to ambulate without pain. If improvement is noted, the patient may be placed in custom full-length semirigid orthotics. He or she may then be referred to physical therapy for stretching of the Achilles tendon and strengthening of the PTT. Steroid injection into the PTT sheath is not recommended, because of the possibility of causing a tendon rupture.
In stage 2 dysfunction, a painful flexible deformity develops, and more control of hindfoot motion is required. In these cases, a rigid University of California at Berkeley (UCBL) orthosis or a short articulated ankle-foot orthosis (AFO) is indicated.
Once a rigid flatfoot deformity develops, as in stage 3 or 4 dysfunction, bracing is extended above the ankle with a molded AFO, a double upright brace, or a patellar tendon–bearing brace. (See the image below.) The goals of this treatment are as follows:
To accommodate the deformity
To prevent or slow further collapse
To improve walking ability by transferring load to the proximal leg away from the collapsed medial midfoot and heel
Because of the fixed deformity, these orthotics must be accommodative rather than corrective. Shoe modifications (eg, larger size or rocker sole) are often required. The chances of success in relieving pain despite these measures are relatively low.
In a study of nonoperative therapy for stage 2 and 3 PTT dysfunction, Chao et al used a rigid UCBL orthosis with a medial forefoot post in nonobese patients with flexible heel deformity correctible to neutral and less than 10° of forefoot varus and used a molded ankle foot orthosis in obese patients with fixed deformity and forefoot varus greater than 10°. Average length of orthotic use was 15 months. Nonoperative therapy yielded good-to-excellent results in 67% of patients. Four patients ultimately elected to have surgery. The authors concluded that orthotic management is successful in older low-demand patients and that surgical treatment can be reserved for those patients who fail nonoperative treatment.
Conservative treatments for AAFD may be summarized as follows:
Stage 1 - NSAIDs and short-leg walking cast or walker boot for 6-8 weeks; full-length semirigid custom molded orthosis, physical therapy
Stage 2 - UCBL orthosis or short articulated ankle orthosis
Stage 3 - Molded AFO, double-upright brace, or patellar tendon–bearing brace
Stage 4 - Molded AFO, double-upright brace, or patellar tendon–bearing brace
The overall medical condition of the patient, the patient's expectations, and the stage of the disease determine the recommended treatment. For example, if the patient has low physical demands or has serious underlying medical problems, he or she should be treated nonoperatively.
Although the four-stage classification cited earlier (see Workup, Staging) is not foolproof, it can be very useful in the discussion of management of AAFD. Regardless of the stage, however, operative management should only be considered after conservative management (see Medical Therapy) has proved unsuccessful. The surgical procedure chosen should address all the fixed and dynamic deformities for each patient.[63, 64]
Treatment of stage 1 PTT dysfunction is straightforward. The goal is to halt the progression of tenosynovitis through conservative or operative methods in order to prevent tendon rupture. The rigid deformities of stages 3 and 4 necessitate operative correction and fusion of the involved joints in order to produce a plantigrade balanced foot. The principle of fusing the fewest number of joints possible should be followed.
Surgical treatment of stage 2 PTT dysfunction generates the most controversy among foot and ankle surgeons. Many different surgical procedures have demonstrated good short-term relief of pain and improved function but have shown only limited ability to correct the deformity.
For example, a tendon transfer using FDL or flexor hallucis longus (FHL) tendon yields satisfactory short-term pain relief, but it does not achieve arch correction. The addition of a medial displacement calcaneal osteotomy improves heel valgus position, but it may not produce complete correction of the medial longitudinal arch. Lateral column lengthening (LCL) through the anterior calcaneus or through the calcaneocuboid joint achieves arch correction, but it requires an iliac crest tricortical graft and risks nonunion or overcorrection.
In large or obese patients, subtalar or talonavicular fusion may be needed to achieve long-term correction, though these procedures limit hindfoot motion significantly. The most biomechanically sound surgical treatments may be those that use tendon transfer to substitute for the deficient PTT, with LCL to restore alignment of the subtalar and talonavicular joints and medial fusion of the sagging naviculocuneiform joint or first metatarsocuneiform joint. These procedures require multiple steps, multiple incisions, and prolonged recovery time. Perhaps the most important unanswered question is whether arch correction is required to achieve a long-term satisfactory outcome.
Surgical treatments for AAFD may be summarized as follows:
Stage 1 - Tenosynovectomy, tendon debridement, and tendon repair of partial tears
Stage 2 (add Achilles tendon lengthening or gastrocnemius recession in cases of equinus contracture) - PTT repair; FDL or FHL transfer alone; FDL or FHL transfer and calcaneal osteotomy; FDL transfer and LCL; FDL transfer, LCL, and medial column fusion; FDL transfer, LCL, and calcaneal osteotomy; subtalar fusion; talonavicular fusion
Stage 3 - Subtalar fusion; triple arthrodesis
Stage 4 - Tibiotalocalcaneal fusion; pantalar fusion
Surgical Therapy for Stage 1 AAFD
By definition, patients with stage 1 pes planus do not demonstrate clinical deformity and are the group with the highest likelihood of responding to conservative management (see Medical Therapy). If the patient's condition does not improve with conservative management or if the patient's symptoms are sufficiently chronic in nature, then consideration can be given to surgical intervention. The exact nature of this intervention has been debated.
Traditionally, operative treatment of stage 1 disease has involved release of the PTT sheath, tenosynovectomy, debridement of the PTT with excision of flap tears, and repair of longitudinal tears. A short-leg walking cast is worn for 3 weeks postoperatively. Teasdall and Johnson reported complete relief of pain in 74% of 14 patients undergoing this treatment regimen for stage 1 disease. A retrospective review of young athletes with stage 1 disease who were treated with surgical debridement revealed an "excellent likelihood to return to the previous level of athletic activity."
Debridement should be reserved for patients who show no clinical deformity or weakness. It has been suggested that surgical debridement of tenosynovitis in early stages may prevent progression of disease to later stages of dysfunction.
Surgical Therapy for Stage 2 AAFD
Treatment of the flexible deformity of stage 2 PTT dysfunction is controversial. Many patients with stage 2 AAFD, like those with stage 1, can be effectively treated nonoperatively with orthoses (either a short articulated AFO or a foot orthosis) and structured exercises (see Medical Therapy). Alvarez et al studied nonoperative management of patients with stage 1 and 2 AAFD (without complete tendon rupture). At the conclusion of the treatment protocol, most patients had "minimal or no pain, could walk on tiptoes, were not limited by walking distance, and could perform a painless SSHR [single-sided heel rise]."
If appropriate conservative treatment fails for patients with stage 2 disease, surgical management may be considered. The exact surgical procedure chosen for stage 2 varies widely, and numerous bone and soft-tissue reconstructive surgeries have been described to treat the various presentations of stage 2 pathology. The multitude of surgical procedures proposed for stage 2 dysfunction is evidence of the difficulty of obtaining an excellent surgical result in this setting. Procedures that have been reported to yield satisfactory outcomes include the following:
Direct repair of the torn tendon
Tendon transfer or tenodesis using the FDL or the FHL
Medial displacement calcaneal osteotomy
Limited arthrodeses of the hindfoot or midfoot
Achilles tendon lengthening is recommended if ankle dorsiflexion is limited to 10° or less.
Typically, surgical management of stage 2 disease involves both a soft-tissue reconstruction (FDL transfer; see the image below) and a bony reconstruction (medializing calcaneal osteotomy) reconstruction.[68, 53] This procedure has yielded excellent results with minimal complications and a high satisfaction rate. Additionally, it yields significant and lasting improvement in radiographic parameters, including the lateral talometatarsal angle and the tibiocalcaneal angle.
The osteotomy (and subsequent medial shift) of the calcaneal tuberosity shifts the moment arm of the gastrocnemius-soleus complex medial to the subtalar axis. This then generates an inversion force that protects the medial soft-tissue reconstruction and corrects the hindfoot alignment. The transferred FDL muscle hypertrophies significantly as it compensates for the diseased PTT.
Stage 2 surgical intervention also typically involves a lengthening of the gastrocnemius-soleus complex. This can be achieved by means of either a percutaneous Achilles lengthening or a gastrocnemius recession. Prospective data reviewing the gastrocnemius recession have demonstrated no loss of plantarflexion strength at 1 year and, in fact, improved strength in comparison with the preoperative strength of the ipsilateral extremity.
More advanced stage 2 disease may be associated with medial column instability, severe forefoot abduction, or severe forefoot varus. In this clinical scenario, additional reconstructive techniques include both lateral and medial column bony procedures. The lateral column bony procedures include LCL through the anterior process of the calcaneus (joint-sparing) and calcaneocuboid distraction arthrodesis (non–joint-sparing).
LCL through the anterior process of the calcaneus can be successfully performed with autografts, allografts, or metallic implants. These techniques provide powerful corrective forces through medial and plantar translation of the navicular on the talar head, effectively restoring the longitudinal arch and correcting the forefoot abduction.[74, 75]
Medial column bony procedures are indicated when residual forefoot varus exists after lengthening of a lateral column. Residual forefoot varus prevents the creation of a plantigrade foot and results in symptomatic lateral column overload. To reduce this overload, which is associated with LCL, clinical and biomechanical research has supported the use of medial procedures to redistribute load to the medial column.[77, 78]
Such medial column bony procedures include plantarflexion opening wedge medial cuneiform osteotomies (joint-sparing) and plantarflexion arthrodesis of the first tarsometatarsal articulation (non–joint-sparing). Alternatively, medial soft-tissue reconstructive techniques have also proven useful for correcting associated forefoot supination deformities. The Cobb procedure involves use of a partial anterior tibial tendon graft that is rerouted through the first cuneiform to the proximal stump of the PTT.
An additional procedure that is designed to correct the pes planovalgus deformity is subtalar arthroereisis,[80, 81, 82] which involves placement of a plug or screw-type implant in an effort to correct the rotational malalignment of the subtalar joint. The long-term outcome of this procedure has been questioned; a significant number of patients develop persistent sinus tarsi pain that necessitates implant removal. The limited data on this procedure in adult patients are insufficient to permit a recommendation for or against this procedure.
Various procedures performed to treat stage 2 dysfunction are described in more detail below.
The torn tendon may be directly repaired by suturing the ends of an acute rupture. If the tendon is avulsed distally, it can be repaired to the navicular, or the portion of the tendon that is attenuated can be excised and the proximal and distal tendon stumps repaired end to end. Proximal Z-lengthening of the PTT may be needed to achieve direct repair. The distal half of the anterior tibial tendon can be detached proximally and left attached to its insertion into the base of the first metatarsal and used to reinforce the directly repaired tendon.
The PTT often has an irreparable gap or is attenuated and scarred to the tendon sheath. The posterior tibial muscle may function poorly, even if the tendon can be directly repaired. This has led several authors to recommend tendon transfer to substitute for the dysfunctional or irreparable PTT.
Jahss described side-to-side tenodesis of the proximal and distal stumps of the PTT to the intact FDL tendon in five patients, reporting short-term satisfactory results, though all patients had residual heel valgus. Transfer of the FDL tendon to the distal stump of the PTT or directly into the navicular tuberosity through a vertically oriented tunnel has been advocated by several authors ,with good short-term subjective results. The procedure uniformly failed to correct the flatfoot deformity but functioned well in relieving pain and improving inversion strength.
Some authors have emphasized the importance of spring-ligament (calcaneonavicular-ligament) repair or reconstruction in conjunction with FDL transfer. A retrospective study of spring-ligament repair/reconstruction and FDL transfer demonstrated excellent functional results in 14 of 18 patients, though arch correction on radiographs was inconsistent.
Goldner et al reported using the FHL for transfer into the distal stump of the PTT in two patients, of whom one had a previous laceration of the tendon and the other a chronic tear. The younger patient had a full and complete recovery, and the outcome in the other patient was not reported.
Procedural details: FHL tendon transfer
An 8-cm incision is made along the course of the PTT from a point just proximal and posterior to the medial malleolus to the navicular tuberosity. The PTT sheath is opened, and a tenosynovectomy is performed. Partial tears of the PTT are repaired with 2-0 nonabsorbable Dacron sutures. If the PTT is attenuated and irreparable, it is excised, leaving a 1-cm stump attached to the navicular tuberosity. If the spring ligament is torn or attenuated, it is repaired and imbricated with 2-0 nonabsorbable sutures.
The FDL tendon is identified in its sheath just deep to the PTT sheath. The FHL tendon is identified deep to the sustentaculum tali. The FHL tendon is sutured to the FDL tendon distally with 2-0 nonabsorbable sutures and then divided proximal to the anastomosis (see the image below).
A suture anchor is placed in the navicular tuberosity, and the transferred FHL tendon is sutured to the navicular and to the distal stump of the posterior tibial tendon with No. 2 nonabsorbable sutures (see the image below). Tension on the FHL tendon is adjusted with the foot in inversion and plantarflexion. The tendon sheath, subcutaneous tissue, and skin are closed in layers. Percutaneous triple-cut Achilles tendon lengthening or gastrocnemius recession is performed if the foot cannot be easily dorsiflexed past neutral.
After surgery, the foot is placed in a posterior splint in a position of equinus and inversion. A short-leg nonweightbearing cast is applied 3 days after surgery to maintain the position of equinus and inversion and is worn for 4 weeks. The foot then is placed in a short-leg walking cast in a neutral position, which is worn for an additional 2 weeks. A Cam walker boot is worn beginning 6 weeks postoperatively and is removed for range of motion and strengthening exercise. Immobilization is discontinued 10 weeks postoperatively.
Procedural details: FDL tendon transfer
A similar approach is used for the FDL tendon transfer. In this case, the distal FDL is sutured into the FHL, and the FDL is released just proximal to the suture to give adequate length to the tendon. A vertical hole then is drilled into the navicular bone. The surgeon should be careful to leave an adequate bridge of bone in place medially. The plantar hole is rounded smooth proximally to take any sharp edge away that may damage the tendon.
With the aid of a suture passer, the FDL tendon is routed from plantar to dorsal and sutured to itself (if enough tendon length is available) and to the surrounding tissue. The foot is held in an inverted position during this maneuver to place appropriate tension on the FDL tendon. Closure and postoperative care are similar to those for FHL transfer.
Follow-up examination of patients who have undergone FDL tenodesis or transfer alone has not shown consistent correction of deformity. Because of a concern of deteriorating clinical results over time with soft-tissue procedures alone, some surgeons added bony procedures to the soft-tissue reconstruction, theorizing that the restoration of arch height and heel position might produce more durable and improved clinical results. The ideal bony procedure to treat acquired pes planovalgus corrects the foot deformity, decreases strain on the spring and deltoid ligaments, and protects the soft-tissue reconstruction.
Gleich first described a medial and inferior displacement osteotomy of the posterior third of the calcaneus in 1893. Koutsogiannis first described the medial displacement calcaneal osteotomy as a treatment of valgus hindfoot deformity.
The addition of a medial displacement osteotomy through the posterior portion of the calcaneus moves the valgus heel under the weightbearing axis of the leg. The osteotomy also decreases the heel valgus–producing deforming force of the Achilles tendon by shifting the Achilles insertion medially. In vitro studies showed that a 1-cm medializing osteotomy of the calcaneal tuberosity decreases strain on the spring ligament and deltoid ligament. A 1-cm translational calcaneal osteotomy actually moves the center of pressure in the ankle joint 1.58 mm medially.
A retrospective study of 32 patients undergoing FDL transfer and calcaneal osteotomy with an average of 20 months follow-up showed 94% pain relief, improved function, and significant improvement in radiographic arch measurements. Sammarco and Hockenbury reported satisfactory results in 19 patients undergoing FHL transfer and medial displacement calcaneal osteotomy. Although the FHL is stronger than the FDL, postoperative radiographs did not show significant arch correction, indicating that a medial soft-tissue procedure in conjunction with calcaneal osteotomy may not result in arch correction.
Calcaneal osteotomy is employed in conjunction with FDL or FHL transfer and is performed before the tendon transfer. A 5-cm oblique incision is made along the lateral heel from posterosuperior to anteroinferior, running posterior to the peroneal tendon sheath and sural nerve (see the image below). Sharp dissection is used to proceed directly down to bone. Skin flaps are kept thick. The lateral wall of the calcaneus is exposed subperiosteally with a Key elevator. Small Hohmann retractors are placed over the superior aspect of the calcaneus anterior to the Achilles tendon and at the plantar aspect of the calcaneus anterior to the plantar fascial attachment.
A straight, wide power osteotome (Micro-Aire, Inc) or sagittal saw is used to make a cut across the calcaneus in line with the incision at a 45° angle to the plantar surface of the foot and perpendicular to the surface of the calcaneus. C-arm fluoroscopy is used to document proper osteotomy position before the bone cut is made. The medial aspect of the heel is palpated to gauge the depth of the osteotomy and to avoid overpenetration of the osteotome, which could cause injury to the tibial nerve and vessels. The depth of the osteotome cut also can be judged with a Freer elevator during completion of the cut.
After completion of the osteotomy, the medial soft tissues are spread by inserting a large Key elevator into the osteotomy site and levering the calcaneal tuberosity downward. A laminar spreader also can be placed into the osteotomy site and used to spread the medial soft tissues (see the image below).
If the medial soft tissues are adequately mobilized, the tuberosity should be easily translated medially 1 cm. It is important to ensure that the plantar surface of the osteotomy has been adequately mobilized. Otherwise, the posterior calcaneal fragment rotates internally rather than slides medially. The calcaneal tuberosity then is translated 1 cm medially, with care taken to avoid superior translation of the fragment. A surgical assistant then holds the osteotomy in a corrected position while it is fixated with two 4.0-mm diameter partially threaded cancellous screws placed perpendicular to the osteotomy cut (see the image below). Typically, no washers are used.
Placement of the screws into the subtalar joint should be avoided, and the screw heads should be kept off the weightbearing surface of the heel. Screws are placed in a parallel fashion. Because the tuberosity has been shifted medially, the screws should be aimed slightly laterally in order to hit the main calcaneal body; if this is not done, the screw(s) may miss the anterior calcaneus. Screw position is documented by means of intraoperative fluoroscopy (see the image below).
The wound is closed in layers. Postoperative care is the same as for FDL transfer, except that weightbearing is not allowed until radiographs indicate that the osteotomy has healed (usually 6-8 weeks postoperatively).
Lateral column lengthening
The Evans anterior calcaneal lengthening osteotomy lengthens the lateral column of the foot by inserting a 10- to 15-mm bone graft 10-15 mm proximal to the calcaneocuboid joint. This lateral column-lengthening procedure radiographically improves forefoot abduction and hindfoot valgus and restores the medial longitudinal arch.
Cadaveric studies show that LCL protects the calcaneonavicular (spring) ligament form overload during weight bearing. A retrospective study of 19 patients undergoing Evans calcaneal osteotomy in conjunction with posterior tibial tendon repair or shortening and deltoid ligament repair or reconstruction reported six excellent, 11 good, and two fair results. Significant radiographic arch correction was noted at 23-month follow-up.
A cadaver study of Evans calcaneal LCL in normal feet showed elevated calcaneocuboid joint pressures postoperatively, raising questions about potential long-term degenerative arthritis of the calcaneocuboid joint after the procedure. This concern has led to the recommendation of lengthening the lateral column through distraction arthrodesis of the calcaneocuboid joint. However, results of another cadaver study failed to confirm elevation of calcaneocuboid joint pressure after Evans calcaneal LCL in preexisting flatfeet and, in some cases, actually showed lowering of calcaneocuboid pressure after LCL.
A retrospective study of 41 feet undergoing LCL through distraction arthrodesis of the calcaneocuboid joint in conjunction with FDL transfer and selective medial midfoot arthrodesis found satisfactory outcomes in 85% of cases and a uniform radiographic correction of flatfoot, but a calcaneocuboid nonunion rate of 20% was found. Note that this series included several patients who also had fusions of the naviculocuneiform or first metatarsocuneiform joints and that distraction arthrodesis of the calcaneocuboid joint was not the only bony procedure performed.
Thomas et al reported on 25 patients who underwent FDL transfer to the navicular and lateral column lengthening with two different methods. Postoperative American Orthopedic Foot and Ankle Society (AOFAS) scores were 87.9 for the osteotomy group and 80.9 for the calcaneocuboid distraction arthrodesis group, but the difference was not statistically significant. Significant improvement in radiographic parameters was seen in both groups. Complication rates were high in both groups, with an especially high rate of nonunion and delayed union in the calcaneocuboid distraction group.
A combination of FDL transfer to medial cuneiform, medial displacement calcaneal osteotomy, and Evans LCL produced good short-term results in a retrospective study of 17 patients with stage 2 PTT dysfunction. Significant improvement in the AOFAS hindfoot score was seen, and radiographs showed significant improvement in arch measurements at 17.5-month follow-up.
Procedural details: LCL by distraction arthrodesis of calcaneocuboid joint
LCL by distraction arthrodesis of the calcaneocuboid joint is also performed in conjunction with FDL or FHL transfer. A 5-cm dorsolateral incision is made over the calcaneocuboid joint. The sural nerve and peroneal tendons are retracted plantarly. The joint is exposed, and the articular cartilage is removed with osteotomes and curettes.
The joint is distracted with a smooth laminar spreader. An alternative technique is to use a small joint external fixator to distract the lateral column, placing pins in the cuboid and calcaneus. Correction of the medial longitudinal arch and correction of heel valgus to neutral or slight valgus serve as the endpoint for distraction. The forefoot also should be rotated into neutral position before graft insertion.
A trapezoidal tricortical iliac crest graft then is fashioned to fit the distracted joint. The bone graft should be wider both dorsally and laterally, tapering toward the plantar and medial aspects, respectively. A graft width of 8-12 mm usually suffices. A cervical plate placed laterally with two screws in the calcaneus and two screws in the cuboid is used for fixation. (See the images below.) The remainder of the calcaneocuboid joint is filled with cancellous graft.
The postoperative course is the same as for the calcaneal osteotomy, except that weightbearing is delayed until fusion is confirmed radiographically.
The difficulty of achieving consistent and lasting correction of the flatfoot deformity with soft-tissue procedures, whether alone or in conjunction with osteotomies, has led some surgeons to recommend fusion as a treatment of stage 2 deformity. Some surgeons feel that soft-tissue procedures are less successful in patients who are obese and that obesity is an indication for joint fusion.
Kitaoka et al compared subtalar arthrodesis with FDL transfer in vitro and found a more consistent correction of deformity after subtalar arthrodesis. A retrospective study of 21 feet treated with subtalar arthrodesis for PTT dysfunction yielded good-to-excellent results in 16 of 21 feet and significant correction of flatfoot deformity according to radiographic measurements. Stephens et al emphasized the need for reducing the subtalar joint prior to fusion and for differentiating a subtalar repositional arthrodesis from a subtalar fusion in situ.
Another in-vitro study compared subtalar fusion alone, calcaneocuboid fusion alone, talonavicular fusion alone, double (talonavicular and calcaneocuboid) arthrodesis, and triple arthrodesis with respect to their abilities to correct an experimentally corrected flatfoot deformity. Talonavicular or double arthrodesis resulted in better correction of flatfoot deformity than did subtalar fusion alone. A retrospective study of 29 patients with PTT dysfunction treated with isolated talonavicular fusion found good-to-excellent results in 86% of patients at an average follow-up of 26 months.
Johnson et al used subtalar fusion, FDL transfer, and spring-ligament repair in 17 feet with stage 2 dysfunction. At an average follow-up of 27 months, they reported excellent radiographic correction of pes planus deformity and improvement in AOFAS hindfoot score.
Chi et al reported on 65 feet that underwent FDL transfer with LCL and/or medial column fusion. Lateral column fusion was performed for calcaneovalgus deformity with a flat calcaneal pitch angle. Naviculocuneiform or first metatarsocuneiform joints that showed sag on lateral radiographs were also fused. At 1- to 4-year follow-up, 88% of the feet that had LCL, 80% of those that had medial column stabilization, and 88% of those that had medial and lateral procedures were less painful or pain-free. Significant radiographic correction of the deformity was seen in all groups. The authors concluded that fusion of these unessential joints effectively corrected deformity and relieved pain.
Surgical Therapy for Stage 3 AAFD
Because fixed deformity is often associated with symptomatic arthrosis, an arthrodesis is often required for proper correction of stage 3 disease. The goals of surgery are to relieve pain and to restore proper alignment of the foot. The principle of fusing the smallest number of joints possible should be followed.
Isolated arthrodesis of the subtalar joint is indicated in patients with subtalar arthrosis or fixed hindfoot alignment with flexible forefoot deformity. Isolated talonavicular arthrodesis is indicated for management of an unstable talonavicular joint in the presence of a flexible subtalar joint in patients older than 50 years.
On the other hand, a double arthrodesis (fusion of the calcaneocuboid joint and the talonavicular joint without addressing the subtalar joint) is indicated in younger patients. A triple arthrodesis is indicated for cases of a rigid subtalar joint and fixed forefoot varus deformity. Long-term follow-up studies have shown that triple arthrodesis is associated with increased wear in the ankle joint and a higher rate of degenerative ankle arthrosis (ie, disease or degeneration of an adjacent joint or segment, as the forces normally seen in the fused joints or segments are transferred to the next adjacent joint or segment).[98, 99]
To the authors' knowledge, no comparative studies to date have demonstrated a lower rate of adjacent joint arthrosis with the aforementioned limited fusions in comparison with triple arthrodesis. For this reason, triple arthrodesis continues to be the criterion standard for treatment of stage 3 AAFD (see the image below).
Surgical Therapy for Stage 4 AAFD
Stage 4 disease is rare. The valgus ankle in stage 4 dysfunction develops because of deltoid ligament instability. The deltoid ligament is difficult to reconstruct with a tendon transfer. Arthritic valgus ankle deformities secondary to deltoid ligament insufficiency have not been treated successfully with a total ankle arthroplasty because of the inability to achieve ligamentous balance.
Treatment of a fixed subtalar deformity and degenerative ankle valgus requires tibiotalocalcaneal arthrodesis, which involves fusion of the ankle joint and the subtalar joint. If fixed forefoot varus is also present, pantalar arthrodesis may be necessary to realign the foot adequately; this procedure involves fusion of the ankle and the subtalar, talonavicular, calcaneocuboid, and tibiotalar joints.
Either tibiotalocalcaneal arthrodesis or pantalar arthrodesis results in a stiff foot, which results in an altered gait. Shoe modifications and bracing are often required after surgery. These operations are technically demanding and are considered salvage procedures.[102, 103]
Although some of the complications associated with AAFD treatment may be related to poor surgical planning and improper choice of procedure, others may be inherently related to the procedure itself. For example, a flatfoot deformity that is secondary to an arthritic Lisfranc joint may be wrongly diagnosed as a PTT-deficient foot and therefore be treated as such.
Other complications may be related to inadequate surgical intervention. For example, in a study by Michelson et al, tenodesis of the FDL to the diseased PTT proved to have a 50% failure rate after 2 years. Similar long-term failure rates were noted for FDL transfers to the navicular that were performed for stage 2 PTT dysfunctions.
Bony procedures such as a calcaneal osteotomy and various arthrodeses can also be associated with significant complications. Although nonunion of the calcaneal osteotomy is exceedingly rare, placement of hardware to stabilize these osteotomies can be associated with postoperative morbidity. Penetration of the subtalar joint or a prominent screw head may cause postoperative symptoms. Risks associated with a triple arthrodesis include higher rates of nonunion—in some cases, exceeding 20%—and also malposition, both in hindfoot alignment and in forefoot rotation. Longer-term complications involve arthrosis of adjacent joints.
The major concern with any foot reconstructive procedure is to achieve a painless plantigrade foot that fits into a shoe. Undercorrection or overcorrection of a deformity can easily occur. Soft-tissue procedures alone do not correct the pes planus deformity of PTT insufficiency. Caution must be exercised intraoperatively to ensure that the heel is in slight valgus and that the forefoot is plantigrade and not left in varus. An ankle equinus contracture should not be left untreated.
As with any medial midfoot procedure, care must be taken to avoid neurovascular injury during PTT debridement or FDL or FHL tendon transfer. Many surgical techniques involve suturing the distal stump of the transferred FDL tendon to the adjacent FHL tendon at the knot of Henry. The neurovascular bundle is at significant risk during this anastomosis because of its close proximity. Medial skin flaps should be kept thick to minimize the risk of wound dehiscence.
During medial displacement calcaneal osteotomy, the sural nerve is at risk if the lateral incision is made too far anteriorly. The calcaneal osteotomy is made at a 45° angle to the long axis of the calcaneus through the calcaneal tuberosity. If the osteotomy is made too far anteriorly, the posterior facet of the subtalar joint could be damaged. If the osteotomy is made too far posteriorly, the Achilles insertion could be disrupted. If the osteotome overpenetrates the medial calcaneal wall, the neurovascular bundle could be damaged.
Superior translation of the tuberosity during medial translation of the posterior calcaneal tuberosity must be avoided; if it occurs, the calcaneal pitch could be decreased and the arch flattened further. Two screws are recommended for fixation of the calcaneal osteotomy to prevent rotation of the calcaneal fragment and to enhance fixation, though single large cancellous screws have been used successfully. The screws should be inserted perpendicular to the osteotomy plane, and the subtalar joint should not be penetrated.
LCL achieves arch correction both clinically and radiographically. However, overlengthening of the lateral column is possible, with creation of painful lateral forefoot overload. The Evans calcaneal osteotomy places the sural nerve, peroneal tendons, and anterior and middle subtalar facets at risk. Ideally, the calcaneal osteotomy should be made 10 mm proximal to the calcaneocuboid joint so as to avoid damage to the anterior and middle facets. The high rate of calcaneocuboid joint nonunion during calcaneocuboid distraction arthrodesis also is a concern.
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