Michael Barnett, Arthur Manoli, Bruce J. Sangeorzan, Gregory C. Pomeroy, and Brian C. Toolan
SURGICAL MANAGEMENT
Preoperative Planning
Imaging studies are reviewed.
Physical examination should be done to test for rigidity or flexibility of the foot.
Plain radiographs should be examined for arthritic changes, with triple arthrodesis reserved for severe, rigid deformity.6
CT scanning can aid in determining arthritis when plain radiographs are unclear but suspicion is high.
A tight Achilles tendon should be addressed during the same procedure (gastrocnemius recession, percutaneous, or open Achilles lengthening).
Coleman block testing confirms forefoot-driven hindfoot varus or primary hindfoot varus.
Concurrent problems, such as lateral ankle instability, should be addressed during the same procedure.
Positioning
The patient is positioned supine on the table with the heel resting at the end of the bed (FIG 1).
Thigh tourniquets are used and well padded.
FIG 1 • Positioning for cavovarus reconstruction. The patient is supine with a bump under the ipsilateral hip. The foot is placed perpendicular to the floor to facilitate medial and lateral foot access.
A bump is placed beneath the ipsilateral hip until the foot is perpendicular to the table to facilitate medial and lateral exposures if needed.
The leg is prepared to the knee.
Approach
Achilles tendon pathology is addressed first so this will minimize the deforming force on the heel when shifted.
Either a lateral displacement or Dwyer-type osteotomy is performed, depending on the surgeon's preference, if rigid heel varus is present.
The lateral displacement osteotomy is used for most adult cases, as the Dwyer weakens the moment arm of the Achilles and often cannot achieve the desired correction.7
Through the same incision, a peroneus longus to brevis transfer is done if appropriate.
Attention is then turned toward the first metatarsal, where a dorsiflexion osteotomy of the first ray is performed until the first ray is out of plantarflexion.
This is the most common location needing osteotomy in our practice.
For more severe cases, multiple metatarsal dorsiflexion osteotomies may be required in a similar fashion.5
More advanced cases with extensive cavus through the midfoot and forefoot may require dorsal wedge osteotomies at more proximal levels, as described by multiple authors.2,3
Adequate preoperative planning should alert the surgeon to the need for these more advanced procedures.
A plantar fascia release is useful as an adjunct when midfoot flexion is severe and prevents adequate reduction of the forefoot after osteotomy.
This can also be done first in deformities associated with increased calcaneal pitch, where a proximal slide of the calcaneus is being done to lower the arch.
A Jones procedure can be used to correct residual claw hallux with Girdlestone and Taylor hammer toe procedures for the lesser toes if required.
Transfer of the tibialis posterior to the lateral cuneiform is a useful adjunct in cases of Charcot-Marie-Tooth associated with dorsiflexion weakness of the ankle.4
TECHNIQUES
GASTROCNEMIUS RECESSION
Isolate the gastrocnemius fascia through a longitudinal incision just distal to the musculotendinous junction of the gastrocnemius on the medial side of the leg (TECH FIG 1).
Identify the deep fascia of the leg and incise it in line with the incision, revealing the muscle and tendon structures beneath.
The plantaris tendon will be visible along the medial border of the tendons and may be cut.
Using blunt dissection, the separation of the deep soleus and the more superficial gastrocnemius can be recognized.
The gastrocnemius fascia is easily isolated using a pediatric vaginal speculum, but various retraction techniques may be employed.
Retraction helps protect the sural nerve, which lies adjacent to the gastrocnemius at this level near the midline.
Once isolated, cut the entire fascia transversely using tenotomy scissors.
Fifteen to 20 degrees of increased ankle dorsiflexion with the knee extended can usually be obtained.
Reapproximate the deep fascia using 3-0 absorbable sutures.
TECH FIG 1 • A. Location of incision along medial leg. B. Deep fascia has been incised, revealing division of gastrocnemius and soleus fascias. C. Gastrocnemius fascia is isolated and cut from medial to lateral using tenotomy scissors. This protects the overlying sural nerve and saphenous vein.
LATERAL DISPLACEMENT CALCANEAL OSTEOTOMY AND PERONEUS LONGUS TO BREVIS TRANSFER
The incision to accomplish both of these procedures is made inferior to but parallel to the peroneus longus tendon (TECH FIG 2).
Deepen the dissection from the original incision until the peroneal tendons are identified.
Enter the sheaths for the length of the incision, making sure to preserve the superior peroneal retinaculum (SPR).
The SPR may be taken down directly off the posterior fibula and reattached with a suture anchor if tendon pathology exists such as tears or instability, such as in our example.
Otherwise, the tendons can be sutured together, preserving this structure.
Remove a section of the peroneus longus with a knife.
Reapproximate the longus and brevis tendons proximally and hold them together with figure 8-0 nonabsorbable suture, making sure the knot does not impinge below the SPR.
Carry dissection inferior to the sural nerve, taking care to identify and protect it.
Once the calcaneus is reached, carry the subperiosteal dissection inferior.
Place small Hohmann retractors superior and anterior to the calcaneal tuberosity, protecting the insertion of the Achilles tendon and the origin of the plantar fascia, respectively.
With soft tissues protected, use a sagittal saw to make the osteotomy perpendicular to the axis of the calcaneus.
Shift the free tuberosity piece lateral until a physiologic valgus position of 5 degrees is obtained (usually 8 to 10 mm).
Make a midline longitudinal incision just off the posterior plantar heel pad.
Carry dissection straight through subcutaneous fat to bone.
An assistant or Kirschner wire holds the heel shift in the corrected position while two 6.5-mm partially threaded cancellous screws are placed in lag fashion.
The screws should be off the posterior weight-bearing surface of the heel and should not penetrate the subtalar joint.
Use a rasp to smooth down the prominent lateral bone after the heel shift.
TECH FIG 2 • Lateral displacement calcaneal osteotomy and peroneus longus to brevis transfer. A. Lateral incision over hindfoot just posterior to peroneal tendons. B. Dissection carried down to the peroneal tendons, with the superior peroneal retinaculum still intact. C. With the superior peroneal retinaculum flap taken posterior, a section of the peroneus longus is removed. D. The peroneus longus has been sutured to the brevis, making sure the knot does not impinge under the superior peroneal retinaculum through range of motion of the tendon. E. Sural nerve is identified as dissection is carried inferior. F. A saw is used to cut across the calcaneus, perpendicular to its long axis, protecting the Achilles and plantar fascia. G. An assistant holds the lateral shift while two 6.5-mm partially threaded cancellous screws are placed across the osteotomy. H. Final screw positioning as seen from lateral and superior views.
DWYER LATERAL CLOSING-WEDGE CALCANEAL OSTEOTOMY
Use the approach outlined above for the lateral sliding calcaneal osteotomy.
Instead of a transverse cut with a shift, remove a wedge of bone, based laterally, using a sagittal saw (TECH FIG 3).
The size of the wedge depends on the desired correction but should bring the heel to a physiologic valgus position.
Once the bone is removed, dorsiflex the foot to close the wedge and proceed with fixation as described previously.1
TECH FIG 3 • Dwyer calcaneal osteotomy. Instead of a straight cut through bone, a lateral-based wedge is removed.
FIRST METATARSAL DORSIFLEXION OSTEOTOMY
Make a dorsal incision over the proximal first metatarsal and carry dissection down to the extensor tendons (TECH FIG 4).
Retract them lateral so dissection can be carried down to bone.
Subperiosteal dissection allows exposure of the proximal metatarsal to the first tarsometatarsal joint.
Mark a line transversely on the bone 1 cm from the joint for the bone cut.
Place small Hohmann retractors around the bone to protect the soft tissues, and perform a dorsal closing-wedge osteotomy using a sagittal saw.
The first cut is through 90% of the bone and perpendicular to the diaphysis.
The second cut is 2 to 3 mm distal and angled back toward the plantar endpoint of the first cut.
Complete the first cut and remove the bone wedge. Take enough bone to restore anatomic alignment of the talus and first metatarsal on the lateral radiograph (about 0 degrees).
TECH FIG 4 • First metatarsal dorsiflexion osteotomy. A. Plantarflexed first ray. B. Incision over first metatarsal. C. Measuring 1 cm from first tarsometatarsal joint. D. A small dorsally based wedge is removed. E. The wedge is closed and held with a screw recessed in the first metatarsal. F. Final first ray position.
Use a small burr to make a shallow hole in the dorsal bone to recess the screw head.
Reduce the first metatarsal and place a 3.5-mm lag screw from the burr hole across the osteotomy, taking care not to enter the first tarsometatarsal joint.
PARTIAL PLANTAR FASCIOTOMY
Make an incision just distal and parallel to the plantar heel pad (TECH FIG 5).
Dissection through subcutaneous fat exposes the plantar fascia.
When the medial and lateral borders of the fascia are identified, partial or complete release may be undertaken.
Begin transection 1 cm from the origin on the calcaneus and proceed medial to lateral.
More severe deformities may require more of a release.
TECH FIG 5 • Partial plantar fasciotomy. Incision is made over medial hindfoot, off weight-bearing surface, making sure not to disturb nerves. The plantar fascia is cut transversely until desired correction is achieved.
JONES PROCEDURE
The interphalangeal (IP) fusion of the great toe begins with a transverse incision over the IP joint dorsally (TECH FIG 6).
Cut the extensor hallucis and make an arthrotomy in the joint, freeing up the collateral ligaments.
Use curettes to remove the articular cartilage and use a 2-mm drill bit to fenestrate both sides of the joint.
Place a Kirschner wire from proximal to distal through the distal phalanx and out the tip of the toe just under the nail, leaving minimal wire within the joint.
Place the wire retrograde across the IP joint while holding it reduced.
Make a transverse incision at the toe tip to allow drilling over the wire.
Measure the length of screw so it does not penetrate the metatarsophalangeal joint.
Place a 4.0-mm partially threaded cannulated screw over the wire for compression.
Confirm the position on fluoroscopy and remove the wire.
Center a dorsal midline incision over the first metatarsal neck.
Identify the extensor hallucis longus and bring its distal end into the wound.
Make 4.0-mm drill holes on the medial and lateral aspects of the metatarsal neck and connect them using a curette.
Pass the tendon from lateral to medial through the hole and suture it back on to itself using nonabsorbable suture while holding the ankle in a neutral to slightly dorsiflexed position.
TECH FIG 6 • Jones procedure of first toe. A. Incision is made transversely over the interphalangeal joint to remove cartilage and harvest extensor hallucis longus tendon. B. Incision is made longitudinally over the first metatarsal, transferring the tendon to the neck, and a screw is placed across the interphalangeal joint in lag mode.
POSTOPERATIVE CARE
Posterior sugar-tong splinting is used immediately postoperatively with the ankle in neutral dorsiflexion.
Skin staples are removed at 2 weeks.
Patients are kept immobilized and non–weight-bearing for a total of 8 weeks, and weight bearing is begun when bony healing has occurred.
OUTCOMES
Long-term studies of cavovarus correction in adults are lacking, likely given the varied presentation and multiple modes of treatment for the disorder.
Early treatment while feet are flexible is advised to prevent more extensive procedures required for rigid deformities and complications from progressive arthrosis.
COMPLICATIONS
Painful hardware
Infection
Recurrence of deformity
Wound dehiscence
Nonunion
REFERENCES
· Dwyer FC. The present status of the problem of pes cavus. Clin Orthop Relat Res 1975;106:254–275.
· Jahss MH. Tarsometatarsal truncated-wedge arthrodesis for pes cavus and equinovarus deformity of the fore part of the foot. J Bone Joint Surg Am 1980;62A:713–722.
· Japas LM. Surgical treatment of pes cavus by tarsal V-osteotomy: preliminary report. J Bone Joint Surg Am 1968;50AL927–944.
· McCluskey WP, Lovell WW, Cummings RJ. The cavovarus foot deformity: etiology and management. Clin Orthop Relat Res 1989; 247:27–37.
· Sammarco GJ, Taylor R. Cavovarus foot treated with combined calcaneus and metatarsal osteotomies. Foot Ankle Int 2001;22:19–30.
· Wetmore RS, Drennan JC. Long-term results of triple arthrodesis in Charcot-Marie-Tooth disease. J Bone Joint Surg Am 1989;71A: 417–422.
· Younger AE, Hansen ST. Adult cavovarus foot. J Am Acad Orthop Surg 2005;13:302–315.