Revisional surgical reconstruction of a failed flatfoot mandates a vigilant, global approach consisting of a thorough clinical and radiographic examination and advanced medical imaging. The goal of revisional flatfoot surgery should focus on anatomic and functional restoration in order to decrease pain and improve function. Basic sound principles are necessary to provide improvement. It is imperative to create an in-depth understanding of each specific anatomical fault consisting of the 3 cardinal anatomical planes to accurately identify and diagnose the pathological shortcoming of the previously failed reconstruction. The revision surgery typically will require undoing the isolated pathology or the construct of the index reconstructive surgery. This typically will consist of hardware removal, aggressive bone debridement/resection, possibly bone grafting, and balancing the soft tissues and osseous alignment of the foot and ankle. These techniques and principles are essential in order to revise the anatomical faults that result in balancing and stabilizing the foot and ankle.
One cannot attempt to approach the revisional flatfoot without truly understanding all aspects of the pes planovalgus deformity. The intricate nature of a previous failed flatfoot surgical reconstruction deformity creates a complex decision process for the foot and ankle surgeon with procedure selection. The procedure selection may result in additional potential complications of each distinct procedure or a combination of procedures, which may ultimately lead to failure of the reconstruction. Revision of the failed flatfoot reconstruction is a difficult problem for the patient and the surgeon; therefore, a diligent and detailed evaluation of the patient both clinically and radiographically is mandatory. A thorough physical examination will determine the specific anatomical location and the cause of the failure of the index failed flatfoot reconstruction. Residual and secondary deformity of the particular anatomical location or malformation is crucial to determine. Residual deformity may occur within the soft tissue and/or bony structures of the lower extremity. The deformities may be isolated or in combination in the lower extremity, ankle, hindfoot, midfoot, and/or the forefoot. In addition, residual deformity may be associated with undercorrection or overcorrection of the index attempted surgically corrected procedures resulting in medial or lateral column instability or stiffness. If there is no residual malalignment, symptoms are likely representative of the complications at the isolated site located where the prior procedures performed may have resulted in a nonunion/malunion.
Surgical correction of the failed flatfoot reconstruction is often required and typically will consist of a combination of osteotomies, arthrodesis, and soft tissue balancing procedures. The soft tissue procedures such as tendon transfers or tendon lengthening may be essential to balance the foot and/or ankle. Preoperative planning consists of a thorough clinical examination (consistent with weight-bearing and non-weight-bearing), a vascular examination, and radiographic and advanced medical imaging. This is paramount to achieve a good understanding of the pathology present. The goal is reconstruction of the deformities that results in good surgical outcomes that result in a well-balanced, durable, functional, and plantigrade foot and ankle.
The revision of a previous unsuccessful flatfoot deformity initially presents as an acquired deformity with unsuccessful surgical results. The most common etiology of the adult acquired flatfoot is attributed to the dysfunction of the posterior tibial tendon. The posterior tibial tendon acts as a pulley to assist in dynamically stabilizing the medial longitudinal arch, plantarflex the ankle, and supinate the foot. Through inversion of the subtalar joint, this locks the midfoot and subsequently prevents pronation throughout the oblique axis of the midtarsal joint. Dysfunction of this kinematic process tends to compensate with a mechanical overpull from the peroneus brevis tendon, which causes the hindfoot to enter a valgus position. Furthermore, posterior tibial tendon dysfunction can advance and cause the deltoid ligament complex to attenuate and allow the talus to adduct and plantarflex, which unlocks the midtarsal joint leading to more instability and deformity. Pes planovalgus can be characterized by the supination and abduction of the forefoot with a valgus heel and collapsed medial longitudinal arch.1
A common classification used to categorize the distinctive stages of posterior tibial tendon dysfunction was originally created by Johnson and Strom. Stage I includes tendonitis and/or synovitis with no osseous deformity.2 In this stage, the posterior tibial tendon functions normally and length is maintained. Stage II includes posterior tibial tendonitis but progresses with a flexible acquired flatfoot deformity. The American College of Foot and Ankle Surgeons further subdivided the second stage in IIA and IIB. Stage IIA is defined as having a flexible deformity with minimal hindfoot valgus and abduction of the forefoot with less than 50% talonavicular subluxation. Stage IIB is characterized as a flexible deformity with moderate to severe hindfoot valgus and talonavicular subluxation. Stage III is attained when the long-standing flatfoot deformity has transitioned into becoming more rigid and arthritis of the hind-foot may be noted. The final stage, stage IV, was later created by Myerson, which he defined as a rigid and valgus hindfoot deformity with a valgus talar tilt due to an ineffective deltoid ligament complex and spring ligament.3 Aside from posterior tibial tendon dysfunction, there are several other factors that attribute to the severity of pes planovalgus.
Hindfoot valgus is a main contributor to the adult acquired flatfoot. Correcting a valgus hindfoot by realigning it back into a rectus position allows for the insertion of the Achilles tendon to re-establish itself medially to the subtalar joint axis of motion, subsequently enhancing supination from the Achilles tendon. Insufficient correction of a hindfoot valgus inhibits this type of supination. However, overcorrecting the deformity can lead to excessive supination that can overload the lateral column.4–6
Midfoot abduction and forefoot supinatus are important components to consider when correcting pes planovalgus. In the midstance phase of gait, an unlocked midtarsal joint permits for the contraction of the Achilles tendon to plantarflex the hindfoot on the forefoot. The aforementioned forces of this process can cause an overload of the spring ligament, the posterior tibial tendon, and the plantar aponeurosis. The biomechanics of this can lead to lateral periarticular subluxation, which results in both midfoot abduction and forefoot supinatus. Forefoot supinatus can eventually evolve into a fixed varus deformity. Failure to identify the rigidity of the varus deformity can lead to improper procedure selection when correcting for pes planovalgus.4–6
Conti et al concluded that correcting the talonaviclar joint to a position of adduction for patients with a stage II adult acquired flatfoot deformity was correlated with decreased clinical outcomes in activities of daily living and quality of life when directly compared with an abducted position. The results imply that overcorrection to a position of midfoot adduction can lead to unfavorable outcomes for the reconstruction in patients with stage II adult acquired flatfoot.7
An equinus contracture can also dramatically enhance the deleterious effects of lateral peritalar subluxation; thus, it should be properly identified and corrected. Failure to correct for equinus may increase the likelihood of insufficient flatfoot correction.8 Thus, it is essential that the role of equinus be thoroughly evaluated and effectively treated with the indicated procedure, such as a gastrocnemius recession or tendo-Achilles lengthening.
Ankle valgus is a critical element in identifying the end stages of the pes planovalgus. It is essential that the surgeon always be aware of this specific aspect of the deformity. If not properly addressed during flatfoot reconstruction, ankle valgus will continue to result in malalignment and the progression of ankle arthrosis.6,8,9
Numerous elements can lead to failure of the initial primary correction of a pes planovalgus deformity. Nonunions can occur for a multitude of reasons, such as inadequate joint preparation, insufficient fixation, hardware failure, and lack of sufficient augmentation. Malunions of a flatfoot correction can be the result of undercorrecting or overcorrecting for the deformity, especially when correcting midfoot abduction and forefoot supinatus as previously stated. It is also imperative that the foot and ankle surgeon properly identify between a flexible and rigid deformity; otherwise, an improper surgical procedure may be selected that will probably fail to correct the underlying issues. Therefore, it is essential that when proceeding with a revisional correction for pes planovalgus the foot and ankle surgeon thoroughly considers all elements that are attributing to the deformity (Figure 16.1).
Pain secondary to malunion, nonunion, malalignment, or a combination are key indications for necessary revisional correction of a previously unsuccessful pes planovalgus. The most common indication for revisional surgery of the adult acquired flatfoot is undercorrection of hindfoot valgus.10,11 Frequently, a valgus malalignment can lead to the degeneration of the deltoid ligament complex of the ankle. Several studies suggest that realignment of the hindfoot will subsequently restore medial stability and drastically improve the function of both the deltoid ligament complex and the posterior tibial tendon.5,8,9
Nonunion is a risk with any osseous surgical procedure but can be avoided with effective joint debridement, utilization of bone graft, and stable rigid internal fixation. Therefore, revisional surgery is often indicated when inadequate joint debridement had occurred, the fixation is insufficient, and/or the hardware has failed. Finally, if the patient continues to have pain with residual deformity and no relief from nonoperative care, surgical revision may be the most optimal scenario for the patient (Figures 16.2–16.4).
Clinical case scenarios where surgical revision is contraindicated include patients with active infections, open wounds, and confirmed acute osteomyelitis. Surgery may need to be staged until the soft tissue and bone infection is controlled or in a better state for surgery.
Patients with inadequate vascular perfusion to their lower extremity should not undergo elective revision reconstructive surgery until vascular intervention is implemented. Blood flow should be effectively restored to the lower extremity prior to the reconstructive surgery. With inefficient perfusion to the lower extremity, this will create an increased risk to the surgical site and possibly cause the patient to be more susceptible to postoperative complications.
When facing a revision surgery, the main question the foot and ankle surgeon must answer when approaching the failed flatfoot is “why did it fail?” Many times, failure to recognize or address each aspect of the deformity can lead to unsuccessful revision surgery. The authors recommend working from proximal to distal or from a point of most stability to least stability when performing surgery.
Failure to recognize an isolated gastrocnemius equinus or a gastrocnemius-soleus contracture as an underlying cause of the deformity will lead to malreduction. The Silfverskiold test should be performed appropriately to determine which specific contracture is involved. Performing the Silfverskiold test appropriately will identify whether the patient is experiencing a bony block equinus, a gastrocnemius muscle or a gastrocnemius and soleus contracture. If there is an increase in the degree of dorsiflexion with the knee flexed versus extended then a gastrocnemius contracture is present.12 A posterior muscle group contracture due to a gastrocnemius contracture can be addressed by an endoscopic or open gastrocnemius recession. Gastrocnemius recession offers predictable results with a relatively low morbidity rate.13,14 Rush et al examined 126 patients who underwent an open gastrocnemius recession. Of 126 patients, 9 experienced postsurgical complications including painful scar formation, wound dehiscence, and superficial infection.15 Brandão and colleagues evaluated 697 ft in 627 patients who underwent endoscopic gastrocnemius recession. They had an overall complication rate of 7.5%, which included plantarflexion weakness (3.5%), sural nerve injury (3.0%), and wound complications. If a tight gastrocnemius-soleus complex is the cause of the contracture then a tendo-Achilles lengthening can be performed.16