Donald R. Bohay and John G. Anderson
DEFINITION
Posterior tibial tendon insufficiency is a common diagnosis in the foot and ankle surgeon's practice, and the most common cause of unilateral acquired flatfoot deformity.
The constellation of presenting findings typically include painful flatfoot deformity, dorsolateral peritalar subluxation, and hindfoot valgus.
The degree of hindfoot deformity and stiffness is variable and may be classified along the continuum described by Johnson and Strom (and Myerson) from stage I (mild posterior tibial tendinopathy without hindfoot deformity) to stage IV (severe posterior tibial tendon insufficiency, severe hindfoot deformity, and valgus talar tilt).
Optimal treatment continues to be debated.
Lateral column lengthening, either used in isolation or in combination with other procedures, is our preferred technique for the treatment of the posterior tibial tendon insufficient foot with supple deformity.5
ANATOMY
The lateral column can be defined as the sum of the fourth and fifth tarsometatarsal joints, cuboid, calcaneocuboid joint, and calcaneus.
The peroneus brevis inserts on the base of the fifth metatarsal and is the natural antagonist to the posterior tibial tendon.
The calcaneocuboid joint is the primary motion segment of the lateral column.
Fusion of the calcaneocuboid joint has no impact on subtalar joint motion and decreases talonavicular joint motion by one third.1
PATHOGENESIS
As the posterior tibial tendon and secondary support structures (plantar medial ligaments, including the spring ligament) fail, the midfoot displaces laterally on the hindfoot.
The contracted Achilles tendon and gastrocnemius muscles plantarflex the calcaneus.
The navicular and medial cuneiform are displaced dorsal to the talus.
The forefoot loses its ability to supinate.
With this progressive deformity, the posterior heel shifts lateral to the axis of rotation through the talus, causing the contracted Achilles tendon or gastrocnemius muscles to function as strong hindfoot evertors, thereby worsening the alignment.
The deformity increases as the lateral column is functionally shortened and the lateral talus creates impingement in the sinus tarsi,3 and eventually on the anterior process of the calcaneus.
We characterize this progressive deformity as dorsolateral peritalar subluxation.
NATURAL HISTORY
A functionally shortened lateral column occurs in the patient with the supple deformity described in stage II of Johnson and Strom's classification system.
As the deformity approaches its maximum, the static restraints of the medial column fail and it is effectively lengthened through collapse of the naviculocuneiform or first metatarsal–cuneiform joint.
The sinus tarsi will close and lateral impingement will become a significant clinical finding.
The peroneus brevis may become contracted and the Achilles and gastrocnemius contracture worsens.
Over time a supple or flexible deformity may become rigid and irreducible.
Generally, no radiographic evidence of calcaneocuboid joint arthritis is noted.
A structurally shortened lateral column occurs as noted by virtue of calcaneocuboid joint arthritis.
As the transition from stage II to stage III occurs, the deformity becomes rigid and the ability of the surgeon to correct the deformity with joint-sparing procedures and without arthrodesis of essential joints becomes limited and eventually impossible.
PATIENT HISTORY AND PHYSICAL FINDINGS
As the patient moves through the clinical stages of posterior tibial tendon insufficiency, the complaints will vary from vague discomfort behind the medial malleolus and swelling to increasing deformity, lack of propulsion power, inability to single toe raise, and finally lateral-sided “ankle” pain.
This lateral-sided “ankle” pain usually represents sinus tarsi impingement as the lateral shoulder of the talus impinges on the sinus tarsi.
The deformity will continue to be supple in the early stages.
Eventually the deformity will increase and become rigid, with the complaints ranging from a tired, weak foot with medial arch pain and lateral-sided “ankle” pain to increasing ankle deformity and joint pain and potentially ipsilateral knee and hip pain.
IMAGING AND OTHER DIAGNOSTIC STUDIES
Plain radiographs should be obtained with weight bearing to adequately describe the alignment of the foot. The talo–first metatarsal angle describes the sag of the arch when drawn on the lateral view and the abduction of the forefoot when drawn on the AP view.
Plain foot radiographs should also be examined for the presence of hindfoot arthritis, midfoot arthritis or instability, and the presence of an accessory navicular.
A standing ankle mortise view should be obtained to rule out the possibility of deltoid laxity (stage IV disease).
MRI is not routinely necessary and may underestimate the severity of disease, but it may be useful in ruling out other pathologies. Findings of posterior tibial tendon deformity typically include fluid in the sheath, dramatic thickening of the tendon, and a heterogeneous signal within the tendon substance, indicating the presence of interstitial tears.
DIFFERENTIAL DIAGNOSIS
Midfoot arthritis resulting in pes planus through tarsometatarsal joint collapse
Medial ankle arthritis
Medial osteochondral lesion of the talus
Neurogenic failure of the posterior tibialis through spinal or central pathology
NONOPERATIVE MANAGEMENT
The resultant flatfoot after posterior tibial tendon failure is irreversible, but symptoms may be controllable in many patients by nonoperative means.
A simple in-shoe semirigid or rigid foot orthotic may provide sufficient arch support to reduce symptoms in some patients.
The gold standard for nonoperative management is the use of a cross-ankle brace. This allows direct control of the tendency of the calcaneus to fall into valgus. The most commonly used and best tolerated is a leather ankle lacer with an incorporated custom-molded plastic stirrup, often referred to as an Arizona brace after a common brand name.2 Other options that may be suitable for higher-demand situations or patients with edema control problems include a hinged molded ankle–foot orthosis (MAFO) or a conventional double-metal upright AFO with a leg strap.
Steroid injections into the posterior tibial tendon sheath are contraindicated as they may directly or indirectly precipitate frank rupture and further collapse.
No brace, physical therapy regimen, or medication has been shown to modify the course of the disease or the ultimate outcome for the tendon. These are all best thought of as modalities to control the symptoms.
SURGICAL MANAGEMENT
Preoperative Planning
The surgeon should obtain and review appropriate bilateral weight-bearing foot and ankle radiographs (FIG 1), assess comorbidities, and consider whether adjunctive procedures are needed.
The surgeon should decide whether to use allograft or autograft.2
The surgeon should note the presence or absence of calcaneocuboid joint arthritis. In our hands, symptomatic calcaneocuboid joint arthritis is an indication to perform the lateral column lengthening through the calcaneocuboid joint and not through the anterior process of the calcaneus.
FIG 1 • Preoperative views of the foot: AP (A), oblique (B), lateral (C). D. Preoperative AP view of the ankle.
Positioning
We position the patient supine with a sandbag bump under the ipsilateral hip (FIGS 2 AND 3).
We routinely use a thigh tourniquet.
We judiciously use fluoroscopy.
Approach
While an Ollier incision may be used, we typically access the lateral column through a longitudinal lateral approach (FIG 4) or occasionally an extensile lateral approach.
FIG 2 • Supine position with popliteal nerve catheter and thigh tourniquet.
FIG 3 • Sandbag under ipsilateral hip.
FIG 4 • Landmarks for lateral approach to the lateral column.
TECHNIQUES
LATERAL COLUMN LENGTHENING VIA ANTERIOR CALCANEUS (EVANS)
Approach
Our standard lateral incision is centered over the calcaneocuboid joint and extended proximally to the sinus tarsi (TECH FIG 1A).
Make the incision about 6 to 8 cm long, parallel to the plantar foot, and perpendicular to the calcaneocuboid joint.
Identify the sural nerve and peroneal tendons and carefully retract them plantarward (TECH FIG 1B).
Elevate the extensor digitorum brevis muscle from the anterior process of the calcaneus to expose the superior corner of the calcaneocuboid joint and the sinus tarsi at the angle of Gissane (TECH FIG 1C).
Place small Hohmann retractors, one in the sinus tarsi and the other plantar to the anterior calcaneus, after subperiosteal dissection enhances the exposure to the lateral column.
TECH FIG 1 • A. Incision site for the lateral approach. B. Lateral incision showing exposure of the peroneal tendons. C. Elevation of the extensor digitorum brevis and retraction of the peroneal tendons with small Hohmann retractors.
Osteotomy
With a Bovie electrocautery or a marking pen, mark a point on the lateral calcaneus 1.5 to 2.0 cm proximal to the superior corner of the calcaneocuboid joint (TECH FIG 2A).
We perform the anterior calcaneal osteotomy with a small oscillating saw and routinely use irrigation to avoid thermal damage to the bone.
Be sure to keep the saw blade perpendicular to the plantar foot.
Take care to avoid injury to the peroneal tendons with the saw (TECH FIG 2B).
Finish the osteotomy with an osteotome, leaving the medial hinge intact (TECH FIG 2C). You may need to obtain an intraoperative fluoroscopy image to confirm that the osteotome is approaching (but not violating) the medial bony hinge; AP and oblique fluoroscopy images typically demonstrate this best.
Place a small lamina spreader in the osteotomy (TECH FIG 2D) and gently spread until the desired correction is achieved.
An intraoperative AP fluoroscopy image of the foot with the lamina spreader in place is useful in determining the amount of correction by appreciating the restoration of talar head coverage by the navicular. The lateral radiograph confirms the lengthening of the lateral column.
By removing the lamina spreader without changing the amount of “spread” on the lamina, the lamina spreader can be used as a caliper to measure the size of the graft (TECH FIG 2E).
The distance between the teeth of the lamina determines the graft size (TECH FIG 2F).
TECH FIG 2 • A. Measuring 1.5 to 2.0 cm proximal from the calcaneocuboid joint. B. Osteotomy of the anterior os calcis using a small oscillating saw. C. Completion of the osteotomy using an osteotome. D. Small lamina spreader is used to distract the osteotomy appropriately. E. Note the open lamina spreader on the back table, to be used as a caliper to measure the bone graft size. F. Measuring the distance between the teeth of the lamina spreader for bone graft size.
When using allograft, use at least a 15-mm-wide iliac crest wedge or patellar wedge. Mark the wedge size from the measurement obtained above and then carefully cut the block in a “pie” or wedge shape, with the cortical side widest (TECH FIG 3A,B).
When using autograft, use a standard approach to the iliac crest, avoiding the superficial branch of the femoral nerve, and make an incision about 6 cm long. Expose the anterior iliac crest using subperiosteal dissection and Taylor retractors. Mark the size of the graft from the measurement previously obtained and score the margins with a curved osteotome. Cut the block as a “pie” or wedge in situ, or remove a standard block and trim it to a “pie” or wedge on the back table.
Place the block into the lateral column osteotomy and tamp it in securely with a bone tamp and mallet. The graft should be flush with the margins of the osteotomy (TECH FIG 3C–E).
Use caution to avoid fracturing the graft. We use a small lamina spreader without teeth and place it in the far dorsal lip of the osteotomy and distract. The allograft comes in just plantar to that and usually can be tamped in with a few taps of the mallet. Avoid striking the allograft central but, rather, on the hard cortical edges.
Avoid subluxation of the calcaneocuboid joint. Occasionally, we temporarily fix the calcaneocuboid joint in its anatomic position with a 0.062 Kirschner wire before implanting the graft.
TECH FIG 3 • A. Marking the bone graft to the appropriate size. B. Bone graft wedge ready for implantation. C. Placing the bone graft into the osteotomy site. D. Tamping the bone graft into place. E.Impacted iliac crest wedge. F–I. Securing the graft with a single 3.5-mm screw from the anterosuperior corner of the calcaneocuboid joint through the graft and into the os calcis. J. AP C-arm image after procedure to confirm graft and screw position. K. Lateral C-arm image.
We secure the graft with a single 3.5-mm screw from the anterosuperior corner of the calcaneocuboid joint across the graft into the proximal calcaneus (TECH FIG 3F–I).
In our opinion, a fully threaded positional screw is ideal and there is no need to apply compression since the graft is already under compression in the distracted osteotomy. In fact, lag technique may lead to crushing the graft.
Supplement the lateral column osteotomy with remaining cancellous bone.
Check clinical alignment.
Use AP and lateral fluoroscopy images to confirm position and restoration of lateral column height, the talo–first metatarsal angle, and correction of dorsolateral peritalar subluxation (TECH FIG 3J,K).
Undercorrection to residual deformity or overcorrection to an adductus deformity can be avoided by checking for desired alignment with the lamina spreader in place, before sizing and inserting the graft.
We routinely close the deeper layers with 3-0 Maxon and the skin using 3-0 nylon.
LATERAL COLUMN LENGTHENING VIA CALCANEOCUBOID JOINT DISTRACTION ARTHRODESIS
Approach
Approach the calcaneocuboid joint through a standard lateral approach centered over the calcaneocuboid joint and extending a total length of 6 to 8 cm, slightly more distal than the approach for lateral column lengthening via the anterior process of the calcaneus.
Identify the peroneal tendons and sural nerve and retract them plantarward, and elevate the extensor digitorum brevis muscle dorsally.
Distract the calcaneocuboid joint with a small lamina spreader and remove the articular cartilage from both sides of the joint.
Drill the subchondral bone with a 2.0-mm drill or a 0.062 Kirschner wire to provide vascular channels.
Distract the calcaneocuboid joint using the small lamina spreader until the desired correction is obtained.
Check AP and lateral fluoroscopy images with the lamina spreader in place. The AP image confirms that the navicular is reduced on the talar head and the lateral view confirms that subluxation of the calcaneocuboid joint is avoided.
Remove the lamina spreader without changing the amount of “spread” on the lamina so it can be used as a caliper to measure the size of the graft.
The distance between the teeth of the lamina determines the graft size.
When using allograft, use at least a 15-mm-wide iliac crest wedge or patellar wedge. Mark the wedge size from the measurement obtained above and then carefully cut the block in a “pie” or wedge shape, with the cortical side widest.
When using autograft, use a standard approach to the iliac crest, avoiding the superficial branch of the femoral nerve, and make an incision about 6 cm long. Expose the anterior iliac crest using subperiosteal dissection and Taylor retractors. Mark the size of the graft from the measurement previously obtained and score the margins with a curved osteotome. Cut the block as a “pie” or wedge in situ, or remove a standard block and trim it to a “pie” or wedge on the back table.
Insert the graft in the calcaneocuboid joint, as flush as possible with the lateral column of the foot, and confirm correction clinically and fluoroscopically.
Maintain congruent alignment of the cuboid and calcaneus during graft insertion.
Secure the arthrodesis with a small H-plate, cervical plate, or semitubular plate (TECH FIG 4).
Avoid overcompression and shortening of the lateral column.
Augment the fusion with further bone graft.
Check overall clinical correction.
AP and lateral fluoroscopy images serve to confirm restoration of lateral column height, talo–first metatarsal angle, and dorsolateral peritalar subluxation.
By checking realignment with the lamina spreader before contouring or inserting the graft, overcorrection to adductus deformity and undercorrection with residual abduction is avoided.
We routinely close the wound with 3-0 Maxon and 3-0 nylon.
TECH FIG 4 • Preoperative AP (A) and lateral (B) radiographs. Postoperative AP (C) and lateral (D) radiographs after lateral column lengthening through the calcaneocuboid joint. (A–D: by permission from Bruce Sangeorzan, MD).
FIG 6 • Immobilization in a bulky Jones dressing and posterior splint dressing postoperatively.
POSTOPERATIVE CARE
We typically immobilize our patients in a postoperative splint (FIG 6).
At 2 weeks, we remove sutures, obtain simulated weightbearing radiographs (AP, lateral, oblique) and the Harris view, and allow touch-down weight bearing in a short-leg cast.
At 6 weeks the patient is transitioned from the cast into a fracture boot and from touch-down to partial weight bearing, with gradual progression to full weight bearing over the next 4 weeks.
Our patients participate in a simple physical therapy protocol to assist with safe mobilization, modalities, and a protocol to strengthen the posterior tibial tendon reconstruction.
In general patients can return to wearing shoes at 10 weeks postoperatively.
OUTCOMES
The selection of autograft versus allograft for lateral column lengthening in the adult does not alter the capacity of the osteotomy to heal.
A prospective, randomized study of 33 patients randomized to allograft versus autograft showed no difference in the union rate.2
Calcaneocuboid joint arthritis has been proposed as a consequence of lateral column lengthening through the anterior process of the calcaneus.
Mosier-LaClair et al4 showed that 14% of their patients had evidence of calcaneocuboid joint arthritis at 5 years of follow-up; however, 50% had calcaneocuboid joint arthritis preoperatively.
Lateral column overload may be more likely with a calcaneocuboid distraction arthrodesis than an Evans-type osteotomy (FIG 7).6
FIG 7 • A–C. Preoperative standing AP foot, lateral foot, and AP ankles. D–F. Postoperative standing AP foot, lateral foot, and Harris view of the os calcis. G. Clinical photograph of the patient viewed from the front, comparing the unoperated side with posterior tibial tendon insufficiency and the corrected side. Note the corrected longitudinal height and forefoot abduction. H. Clinical photograph of the patient viewed from behind, comparing the unoperated side with posterior tibial tendon insufficiency and the corrected side. Note the corrected hindfoot valgus and the absence of a “too many toes” sign.
FIG 8 • A. Radiograph of late graft nonunion and hardware failure. B. Radiograph showing healed revision with plate fixation.
COMPLICATIONS
Nonunion (FIG 8)
Malunion
Graft fracture
Painful hardware
Overcorrection
Peroneal tendon irritation or injury
Sural nerve irritation or injury
REFERENCES
· Astion DJ, Deland JT, Otis JC, et al. Motion of the hindfoot after simulated arthrodesis. J Bone Joint Surg Am 1997;79A:241–246.
· Dolan C, Henning J, Endres T, et al. Randomized prospective study comparing tri-cortical iliac crest autograft to allograft in the lateral column lengthening component for surgical correction of the adult acquired flatfoot deformity. Presented at the 73rd Annual Meeting of the American Academy of Orthopaedic Surgeons, Chicago, March 2006.
· Hansen ST Jr., ed. Functional Reconstruction of the Foot and Ankle. Philadelphia: Lippincott Williams & Wilkins, 2000:198.
· Mosier-LaClair S, Pomeroy G, Manoli A II. Intermediate follow-up on the double osteotomy and tendon transfer procedure for stage 2 posterior tibial tendon insufficiency. Foot Ankle Intl 2001;22: 283–291.
· Mosier-LaClair S, Pomeroy G, Manoli A II. The difficult stage 2 adult acquired flatfoot deformity. Foot Ankle Clin 2001;6:95–119.
· Tien TR, Parks BG, Guyton GP. Plantar pressures in the forefoot after lateral column lengthening: a cadaveric study comparing the Evans osteotomy and calcaneocuboid fusion. Foot Ankle Intl 2005; 26:520–525.