Current Concepts In Tarsal Coalition Surgery

Given the challenges of treating tarsal coalitions, these authors detail helpful clues in the physical exam and diagnostic imaging. They also provide step-by-step pearls for calcaneonavicular bar resection and talocalcaneal coalition resection, and review pertinent keys to postoperative management.

   A tarsal coalition is a fibrous, cartilaginous or osseous union between two tarsal bones created due to failure of segmentation of primitive mesenchyme cells. In general, tarsal coalitions are relatively rare with a reported incidence of 1 to 5.6 percent in the general population.1-3

   Calcaneonavicular (CN) and talocalcaneal (TC) coalitions occur most commonly. They respectively comprise 44 percent and 48 percent of tarsal coalitions. Talonavicular and calcaneocuboid coalitions are each present approximately 1 percent of the time with the remaining 6 percent of coalitions comprised of variations within the tarsal bones.1,4 Researchers have identified coalitions bilaterally in 50 to 60 percent of the general population.5,6

   A tarsal coalition is a congenital abnormality that one may never identify unless it becomes symptomatic. Historically, the literature has described tarsal coalitions as becoming symptomatic in correlation with ossification dates and location.7

   Calcaneonavicular coalitions often present in patients between 8 and 12 years of age with talocalcaneal coalitions becoming symptomatic later in the teenage years or 20s.5 Patients usually present with stiffness and an inability to accommodate uneven surfaces. The mechanical stress on the periosteum creates pain correlating with the children’s vague symptoms and their complaint of the inability to keep up with other children during physical activities.6

   Researchers have attributed acute trauma to the area — consisting of a fall or sprain — to the creation of a painful coalition, especially within the adult population.5 The belief is that this occurs due to microfracturing and further remodeling at the coalition junction, which leads to degenerative changes. Free nerve endings within the periosteum and capsular structures surrounding the coalition become irritated and inflamed.3 There have been no documented cases of nerve endings within the coalition itself.5

   In 2006, Nilsson and Coetzee described the presence of a stress fracture within a calcaneonavicular coalition in a marathon runner.8 We have also had patients present after sustaining a fracture at the coalition site, which resulted in symptoms requiring surgical excision of the coalition to provide long-term relief.

Key Diagnostic Pointers

   Children and adolescents generally present with fatigue and globalized hindfoot pain. Parents often describe their children’s inability to perform certain physical activities or keep up with other children. Adults usually relate a history of subtle trauma with unresolving symptoms.

   Tarsal coalitions may present as a component of severe pes planus deformity. However, they have also been documented in cavovarus feet.9,10 Peroneal and posterior tibial tendon spasms have occurred with these conditions.10 The literature has attributed talonavicular coalitions to clinodactyly, clubfoot and symphalangism.4 In 2007, Strauss, et al., discovered that 2 percent of 160 patients presenting with chronic lateral ankle instability also had concomitant coalitions.11

   During the physical exam, the patient usually demonstrates stiffness within the tritarsal complex with limited frontal plane range of motion. The patient may present with additional medial column collapse, forefoot abduction or heel valgus. A double heel rise test can help determine the flexibility of hindfoot valgus. One can note this by the failure of the heel to resupinate as patients rise on their toes. Reconstitution of the longitudinal arch with dorsiflexion of the hallux is another test to evaluate for any fixed components of the deformity.

Essential Imaging Insights

   One should obtain weightbearing radiographs of the symptomatic foot and ankle. Associated ankle valgus or proximal deformities can be the cause of a severe pes planus foot without the presence of a tarsal coalition. A ball-in-socket ankle joint has also been related to talonavicular coalitions.4

   Physicians routinely take anteroposterior (AP), lateral, oblique and calcaneal axial views for initial evaluation of a suspected coalition. The AP films may demonstrate a broadened navicular (“reverse anteater sign”) or anterior process with relation to a calcaneonavicular bar.12,13 Lateur and colleagues note that lateral films may demonstrate a “C sign” associated with a flatfoot deformity and talocalcaneal coalitions.14

   When a coalition is present, one may also observe a dysmorphic sustentaculum tali (appearing enlarged and rounded), a blunted lateral talar process, a shortened talar neck, and talar beaking.12,13 Oblique views may demonstrate the “anteater sign” associated with a calcaneonavicular bar and bony overgrowth. One may see obliteration of the middle facet of the subtalar joint with an associated talocalcaneal coalition on the calcaneal axial view (also described as the Harris Beath view).

   When utilizing plain radiographs alone, Crim and Kjeldsberg demonstrated an 80 percent sensitivity and 88 percent specificity for talocalcaneal coalitions, and a 100 percent sensitivity and 98 percent specificity for calcaneonavicular coalitions.13 Nonetheless, advanced imaging is usually necessary to rule out occult coalitions, determine the size, and type (fibrous, cartilaginous or osseous) of coalition, and to evaluate periarticular areas for degenerative changes.

   Computed tomography (CT), magnetic resonance imaging (MRI) and technetium-99m bone scanning are all options for evaluation of tarsal coalitions.5 The CT scans help demonstrate the bony adaptations not only at the coalition site but at the adjacent tarsal joints. Researchers have also recommended three-dimensional CT scans to evaluate plantar talar beaking and possible anterior calcaneal facet involvement of a calcaneonavicular bar.15 Calcaneal fibular remodeling has been associated with middle facet talocalcaneal coalitions, which one can identify with a CT scan.16

   Magnetic resonance imaging involves evaluation of not only the bony structures and joints, but also the surrounding soft tissues. This can help identify the type of coalition involved and the presence of any adjacent joint degenerative changes. One can evaluate associated peroneal or posterior tibial tendon pathology at this time.

   In 2005, Rassi et al., described the use of technetium-99m bone scan for evaluation and diagnosis of arthrofibrosis of the middle facet of the talocalcaneal joint. While this condition is similar to a coalition, one cannot visualize it through plain radiographs or a CT scan. Surgical removal can provide long-term relief.17

   One of the key points during evaluation is the acknowledgment of concomitant deformities. Patients can present with an associated flatfoot, equinus or cavus deformity. Lower extremity realignment directly affects the outcome. Surgical treatment should address all symptomatic deformities that are present.18

Weighing The Treatment Options

   Various types of non-operative therapies are available. Short leg casts and activity modification are options for treatment of trauma or chronic pain with associated coalitions within the adolescent and adult population. Pediatric and adolescent patients may have symptomatic improvement with shoe modifications and custom-molded orthoses.1,5,19

   However, we have found that pediatric and adolescent patients sometimes continue to have progressive pain despite care and are unable to perform desired daily activities. Related flatfoot deformities may escalate this process.

   In 2003, Saxena and Erickson observed this phenomenon as only three of 14 patients were able to continue with sports activities after conservative treatment alone. After resection, only two patients were unable to return to desired activity levels.20

   When patients require surgical treatment, the literature notes options ranging from simple coalition resection to a triple arthrodesis.1,21,22 In 1991, Downey described a new surgical classification for tarsal coalitions based on age, articular involvement and associated secondary arthritic changes.22

   The literature has varied on the percentage of talocalcaneal joint involvement required for resection versus arthrodesis. Scranton chose 50 percent of subtalar joint involvement as an arbitrary value for selection of an arthrodesis.23 Subsequently, researchers have described percentages ranging from 33 percent to 50 percent involvement of only the posterior facet as markers for arthrodesis.5,24

   We take an individual approach with each patient to evaluate and develop the appropriate surgical plan carefully. We consider the type of coalition, the physical exam and patient expectations. Joint preservation is a goal in all patients, especially children and adolescents. Adjunctive procedures usually address residual deformities including a flatfoot or equinus. We discuss complications with each patient, including recurrence and the need for further surgery. Patients presenting with tritarsal degenerative joint disease, severe deformity, a high BMI or other demanding physical requirements may be candidates for isolated tarsal fusions or a triple arthrodesis.

A Guide To Resecting The Calcaneonavicular Bar

   When resecting the calcaneonavicular bar, patient positioning and anesthesia are key for surgical success. One would employ general anesthesia while the patient is lying in a supine position with a hip bump for internal rotation. Identify landmarks including the fifth metatarsal base, cuboid, distal fibula, talar head and the intermediate dorsal cutaneous nerve.

   When it comes to the incision, start near the anterior process of the calcaneus and extend it medially while remaining lateral to the intermediate dorsal cutaneous nerve. Perform dissection to expose the extensor digitorum brevis muscle belly. Reflect the muscle belly distally from its origin to expose the calcaneonavicular coalition. With this incision approach, one can identify the talar head, navicular, calcaneus and the cuboid.

   Use osteotomes for resection. Do not use power saws to avoid damage to surrounding articulations. Additionally, this rather small area provides virtually no room for saw blade excursion. The cuts for resection should be parallel to each other and perpendicular to the bony surface. Otherwise, one may resect a wedge rather than a block of bone.

   Additionally, the surgeon may inadvertently resect part of the talar head or sustentaculum tali. One can best visualize these angles by placing osteotomes within each osteotomy site concurrently. Complete the osteotomies by alternating cuts until they are through. The surgeon can remove the bony block by blunt dissection to release all plantar ligamentous attachments.

   It is important to remove enough of the coalition for adequate range of motion without bony abutment and to prevent recurrence. After completing the resection, one should be able to fit a thumb within the resected site. Intraoperative fluoroscopy can aid in proper osteotome placement as well as visualization and verification of adequate resection.

   Researchers have described multiple surgical techniques as adjunctive procedures for prevention of recurrence. Techniques range from simple resection to resection with cauterization, bone wax application or extensor digitorum brevis (EDB) muscle belly interposition.5,7,24

   The surgeon performs muscle belly interposition with use of a Keith needle and suture. Use this needle to thread the belly of the muscle. Then pass the needle through the defect and into the medial arch. Tie the suture percutaneously with a button or gauze.

   Take care to protect the arch from skin necrosis by ensuring adequate soft tissue protection.

   In 2007, Scott and Tuten described a technique for calcaneonavicular bar resection in eight symptomatic feet. At the final follow-up, radiographs demonstrated no signs of recurrence or degenerative changes, and all patients related an improvement in preoperative pain.7 Advocates for muscle interposition relate a decreased rate of recurrence. However, the literature has noted increased complication rates without any remarkable changes in surgical outcomes with relation to pain relief.7

   The surgeon usually closes the skin incision with an intracuticular stitch. Place the patient in a below knee cast. The patient remains immobilized until the soft tissues heal. Release the EDB interposition approximately two to three weeks following the procedure. Then have the patient initiate range of motion exercises and aggressive physical therapy depending on the adjunctive procedures. Physical therapy usually begins three to six weeks following surgery. At this time, the patient transitions back into a shoe.

Salient Pointers On Talocalcaneal Coalition Resection And Associated Procedures

   The surgical technique for resection of a middle facet TC coalition resection is similar to the aforementioned CN technique. The anesthesia and patient positioning are the same. However, the surgeon makes the incision medially over the sustentaculum tali.

   One can resect the coalition in the same manner with confirmation of adequate resection via fluoroscopy. Researchers have described interposition of the defect with adipose tissue, flexor hallucis longus tendon, fascia lata allograft and bone wax.5

   Follow the same realignment principles if a hindfoot arthrodesis is required. The surgeon must first perform coalition resection as well as preparation of the joint surfaces. A bone graft may be required for realignment purposes although this is not common.17, 25

   When it comes to adjunctive procedures one can perform with coalition resection, researchers have cited the Evans calcaneal osteotomy, posterior calcaneal displacement osteotomy, subtalar arthroereisis, medial column arthrodesis and posterior muscle group lengthening.24,26

   The literature is sparse regarding flatfoot reconstruction and tarsal coalition resection. The prevailing focus has been on techniques related to interposition and its correlation with prevention of recurrence.

   Kernbach et al., Wilde et al., and Luhmann et al., have recently addressed the theory of residual flatfoot deformities contributing to unsatisfactory results following coalition resection. Kernbach had promising results with three cases of middle facet resection and flatfoot reconstruction with an American Orthopaedic Foot and Ankle Society (AOFAS) overall score of excellent.24 Wilde and Luhmann noted poorer results with patients having residual hindfoot valgus of 16 and 21 degrees respectively.27,28

   We are proponents of flatfoot reconstruction for patients who have a symptomatic flatfoot with an associated coalition. Surgical treatment options include an Evans and/or posterior calcaneal displacement osteotomy if forefoot abduction and hindfoot valgus are present. Addressing the posterior muscle group equinus is essential for realignment.

   Complications can include wound dehiscence, infection, neuritis and recurrence. One should address these with the patient preoperatively. However, the surgeon can minimize these complications with appropriate surgical planning and technique.

Pertinent Pointers On Postoperative Management

   The goals of surgery include pain relief, realignment, increased range of motion and increased activity level with the ability to function with normal daily activities. Most patients admit sufficient pain relief and the ability to increase their activity level. When it comes to the postoperative physical exam, there is a noted increase in the range of motion of the hindfoot joints.

   Three individual studies evaluated the kinematics and muscle balance on patients following coalition resection. All three demonstrated decreased pain and increased open-chain range of motion. However, this was not consistent with the gait analysis.

   In 2007, Hetsroni et al., demonstrated better plantar pressure results during walking phase but no statistical difference in running patterns between patients with a coalition and two years after resection.29 In 2008, Hetsroni et al., related this same phenomenon in a kinematic analysis of the subtalar joint during walking in pre- and postoperative patients.30

   Lyon et al., had similar conclusions in 2005 and noted no kinematic normalization following surgery. They also noted continued abnormal activity with prolonged monophasic and biphasic activity on electromyelogram (EMG) studies within the peroneal, gastrocnemius and soleus muscles when they compared the operated foot to the non-operated, symptomatic side. These researchers considered flatfoot reconstruction as an adjunctive procedure for possible improvement of results.31

In Conclusion

   A tarsal coalition is a rare condition that sometimes fails to respond to non-operative management. A history, physical exam, radiographs and advanced imaging will guide appropriate surgical planning.

   Realignment, periarticular involvement and postoperative expectations are all part of the surgical workup that can help facilitate a successful outcome. While surgical techniques may vary, applying the basic surgical principles to any tarsal coalition can lead to a successful surgical result.

Dr. Murphy is a third-year resident and is Chief Resident of the Department of Foot and Ankle Surgery at the Western Pennsylvania Hospital in Pittsburgh.

Dr. Mendicino is an Attending Surgeon and Chair of the Department of Foot and Ankle Surgery at the Western Pennsylvania Hospital. He is a Fellow and Past President of the American College of Foot and Ankle Surgeons.

Dr. Catanzariti is an Attending Surgeon and the Director of Residency Training Program of the Department of Foot and Ankle Surgery at the Western Pennsylvania Hospital. He is a Fellow of the American College of Foot and Ankle Surgeons.

For further reading, see “How To Detect And Treat Tarsal Coalitions” in the November 2004 issue of Podiatry Today and “Tarsal Coalition And Pes Planus: What Is The Best Treatment Option?” in the May 2008 issue.

To access the archives or get reprint information, visit www.podiatrytoday.com.

References:

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