Emerging Concepts In Reconstructive Surgery For Stage 2 Flatfoot

Posterior tibial tendon dysfunction is a common condition that foot and ankle surgeons frequently encounter. It is a debilitating pathology, which results in degeneration of the posterior tibial tendon, hindfoot valgus and collapse of the longitudinal arch.  

When staging flatfoot, the most common classification system clinicians use is the Johnson and Strom system.¹ Clinical evaluation and proper imaging are essential in surgical planning. It is necessary to assess reducibility of the flatfoot deformity to help determine the appropriate procedures that one needs to perform.

In order to assess the integrity of the posterior tibial tendon, have the patient attempt a single and double heel raise. Performing a Hubscher maneuver will assess flexibility of the pes planus deformity. Visualization of heel valgus and the “too many toes” sign aids in assessing severity of the deformity. Often, there is pain with palpation along the course of the posterior tibial tendon starting posterior to the medial malleolus and extending to its insertion on the navicular tuberosity. Frequently, the patient will have pain to the sinus tarsi.

Proper imaging is necessary to help in surgical planning. One should obtain three standard weightbearing views of the foot to assess the plane of deformity. Surgeons should measure the talocalcaneal angle, calcaneal inclination angle, talar declination angle, Meary’s line, talonavicular angle, calcaneocuboid angle and the integrity of the cyma line both preoperatively and postoperatively.

Magnetic resonance imaging (MRI) can also be useful in assessing the integrity of the posterior tibial tendon, especially when there is a high index of suspicion for rupture of the posterior tibial tendon. However, an MRI is not always needed for surgical planning as a good clinical assessment with X-rays is usually sufficient. Having intraoperative fluoroscopy is necessary to evaluate alignment of the osteotomies, degree of correction and placement of fixation.

How To Address The Equinus Deformity

We focus on the use of extra-articular osteotomies for reconstruction of the stage 2 flatfoot. In 2018, Wadehra and Fallat performed a retrospective study on 43 patients diagnosed with stage 2 flatfoot.² All of the study patients had a gastrocnemius recession and a combination of medial displacement calcaneal osteotomy, Evans calcaneal osteotomy and Cotton osteotomy without the use of tendon transfer or arthrodesis. With an average follow-up of 60 weeks, all 43 patients held their flatfoot correction with complete resolution of pain.

Flatfoot correction begins with addressing the equinus deformity. If the equinus deformity is due to a gastrocnemius contracture, one would perform a gastrocnemius recession. While there are many techniques for this, we have found that a Strayer technique works well.

Roughly 15 cm proximal to where the Achilles tendon inserts, make a 3 cm incision slightly medial to the midline to avoid the sural nerve as well as the small saphenous vein and its tributaries. Using a hemostat, perform blunt dissection down to the level of the gastrocnemius aponeurosis. This prevents iatrogenic injury to the sural nerve. Then make a transverse incision overlying the aponeurosis while gently dorsiflexing the ankle joint. Upon incising the aponeurosis, one will feel the release and the equinus contracture should be resolved. If there is residual deformity, the surgeon will usually release the intermuscular septa with occasional release of the plantaris tendon.

Pertinent Pearls For The Medial Displacement Calcaneal Osteotomy

Then we perform a medial displacement calcaneal osteotomy. Koutsogiannis originally described this procedure in 1971 to correct the calcaneal pitch and talonavicular subluxation.³ We perform this procedure first to stabilize the rearfoot. The osteotomy realigns the calcaneus with the tibia, allowing for redirection on the vector pull of the Achilles tendon and medially taking strain off the posterior tibial tendon. We begin with a curvilinear incision on the lateral wall of the calcaneus. The surgeons can use a key elevator to remove underlying soft tissue for placement of the osteotomy. Place the osteotomy in an oblique fashion, starting distal to the Achilles tendon and extending just distal to the calcaneal tuberosity. We position the foot in a lateral position and place a K-wire against the calcaneus. With the help of fluoroscopy, we determine where to perform the osteotomy (see photo 1).

Use a sagittal saw to create the osteotomy. Upon approaching the medial wall of the calcaneus, use an osteotome to complete the osteotomy, taking care to protect the medial neurovascular structures. It is important to prevent toggling of the osteotome in the transverse plane because this can greenstick the osteotomy and leave a sharp spike on the medial cortex, which can irritate the tibial nerve. One would subsequently translate the posterior tuber medially no more than 1 cm. We prefer to fixate the osteotomy with two 6.5 headless compression screws. This fixation allows for adequate compression and stability across the osteotomy with prevention of rotation.

Essential Insights On The Evans Calcaneal Osteotomy

After performing the medial displacement calcaneal osteotomy, evaluate the alignment with simulated weightbearing AP and lateral views with use of fluoroscopy. We view alignment of the talonavicular joint and reduction of the talocalcaneal angle. If the talonavicular joint is not reduced, one can perform an Evans calcaneal osteotomy. In 1975, Evans described the lateral column lengthening procedure to offer multiplanar correction.⁴ However, the procedure is very effective for correcting the transverse plane deformity.

We begin with a modified oblique incision proximal to the calcaneocuboid joint, taking care to identify and retract the peroneal tendons and sural nerve. It is often easier to retract the peroneus brevis tendon in a superior approach and the longus tendon plantarly to gain access to the lateral calcaneus. Using assistance from fluoroscopy, place the foot in a lateral position and then place a K-wire against the lateral aspect of the anterior process 1.5 cm proximal to the calcaneocuboid joint (see photo 2).

Use a skin marker on the bone for placement of the osteotomy. The surgeon should ensure sectioning of the dorsal and plantar cortices. Do not make the osteotomy through the medial cortex of the calcaneus. One can utilize sizers from an allogenic bone graft set to wedge the osteotomy site open. Placing the foot for a simulated weightbearing AP view, place different sizers into the osteotomy site until the talonavicular joint is reduced and there is resolution of forefoot abduction.

Once the surgeon has placed the bone graft into the osteotomy, typically, no fixation is necessary as the bone graft usually fits snugly into the osteotomy site. It is common for the surgeon to have to modify the Evans graft to optimize the fit. Often, the graft is too long and the medial surface is blunt, making insertion of the graft difficult. Therefore, shortening the graft may be necessary for proper positioning. Also, it is important to keep the plantar ligaments intact because aggressive dissection can destabilize the calcaneocuboid joint, creating a very unstable Evans osteotomy and displacing the distal portion of the calcaneus.

Keys To Performing The Cotton Osteotomy

After lengthening of the lateral column, we assess the foot for forefoot varus or elevatus of the first metatarsal. If we see a deformity, we perform a Cotton osteotomy. Cotton described this plantarflexory wedge osteotomy in 1936 to correct elevatus of the first metatarsal.⁵

We have noticed adequate correction of Meary’s line with this procedure. We begin this procedure with a 3 cm linear incision over the medial cuneiform. One should take care to retract the extensor hallucis longus tendon laterally. With dissection, we visualize the first tarsometatarsal joint and the naviculocuneiform joint. Placing the foot in an AP and lateral position, center a K-wire over the first cuneiform and use fluoroscopy to confirm the location of the osteotomy (see photo 2).

One can employ a sagittal saw to create an osteotomy from dorsal to plantar, taking care to avoid penetrating the plantar cortex of the cuneiform. The surgeon must also avoid cutting into the intermediate cuneiform when creating the osteotomy. We perform this osteotomy with fluoroscopic guidance. The surgeon places an 0.062 K-wire from dorsal to plantar distal to the osteotomy site to joystick the osteotomy site open (see photo 3). Place sizers from the bone graft set in the osteotomy site until there is complete resolution of the forefoot varus or elevatus deformity. Once one has tamped the bone graft into the osteotomy, perform simulated weightbearing to appreciate resolution of the deformity. Fixation is usually not necessary but if there is instability, one may employ fixation. Once reconstruction is complete, obtain final intraoperative imaging (see photo 4).

A Quick Overview Of The Post-Op Protocol

We have the patients utilize a CAM walker, usually non-weightbearing, for four weeks. Subsequently, the patients transition to partial weightbearing for several weeks followed by full weightbearing in the CAM walker. One can have the patient initiate physical therapy when imaging confirms consolidation of the osteotomy sites.

Dr. Wadehra is a Chief Resident in the Podiatric Surgical Residency Program at Beaumont Hospital-Wayne in Wayne, Mich.

Dr. Fallat is the Director of the Podiatric Surgical Residency at Beaumont Hospital-Wayne in Wayne, Mich. He is a Fellow of the American College of Foot and Ankle Surgeons.

References

1. Johnson KA, Strom DE. Tibialis posterior tendon dysfunction. Clin Orthop. 1989;239:197–206.
2. Wadehra A, Fallat LM, Jarski R. Surgical management of stage 2 adult and pediatric acquired flatfoot without tendon transfer or arthrodesis: a retrospective review. J Foot Ank Surg. 2018;57(4):658-663.
3. Koutsogiannis E. Treatment of mobile flat foot by displacement osteotomy of the calcaneus. J Bone Joint Surg Br. 1971;53(1):96–100.
4. Evans D. Calcaneo-valgus deformity. J Bone Joint Surg Br. 1975;57(3):270–278.
5. Cotton FJ. Foot statistics and surgery. N Engl J Med. 1936;214:353–362.