DEFINITION

The posterior tibial tendon undergoes tearing and degeneration, and as it fails, the foot falls into a planovalgus configuration. Posterior tibial tendon dysfunction (PTTD) is the most common cause of an adult acquired flatfoot deformity.

Most cases occur spontaneously without known antecedent trauma. Women are much more commonly affected than men, with a typical age range older than 50 years.

With time, a rigid deformity develops. The degree and flexibility of the deformity play a key role in determining treatment.

 

 

ANATOMY

 

The posterior tibialis typically degenerates in an area underneath the medial malleolus and distally to its insertion. The process is not inflammatory but is rather characterized by replacement of the normal collagen

fibers with amorphous scar and mucinous degeneration.6

 

As the arch falls, the hindfoot will fall into valgus relative to the leg, whereas the forefoot will abduct through the talonavicular joint. Uncovering of the talar head results as the forefoot pivots laterally.

 

The sag of the arch and the abduction of the forefoot can be described in terms of the loss of alignment of the first metatarsal and the talus. The long axes of these bones should normally be colinear. A sag of the arch is seen by an angulation in this line on the standing lateral radiograph, whereas abduction of the forefoot is seen by lateral angulation of this line on the anteroposterior (AP) view.

 

PATHOGENESIS

 

In most cases, the cause of PTTD is unknown and is not associated with a clear antecedent trauma.

 

The collapse of the arch is the result of a tendon imbalance. The antagonists to the posterior tibialis are the peroneals and they must be functional for the deformity to develop.

 

A single study has suggested a correlation of PTTD with the human leukocyte antigen (HLA) B27 genotype, typically associated with seronegative arthropathies.7

 

Cumulative mechanical factors likely play a role in the development of the disorder; a preexisting planovalgus deformity presumably places extra stress on the tendon and is thought to be a risk factor for degeneration.

 

The presence of an accessory navicular ossicle within the tendon substance at its insertion into the medial pole of the navicular is also a risk factor for tendon degeneration, likely from local mechanical stress (FIG 1).

 

NATURAL HISTORY

 

Dysfunction of the posterior tibialis is thought to be the initiating event in the collapse of the arch.2

 

Early in the course of the disease, pain along the course of the posterior tibialis or weakness of its function will be present without any arch collapse. This is called stage I disease.

 

With time, a planovalgus foot deformity develops. Initially, this deformity is flexible and is called stage II disease.

 

A fixed deformity eventually results; this is called stage III disease. The first component of the deformity to become fixed is usually an elevation of the first ray relative to the fifth ray. This is the result of a compensation of the forefoot for the hindfoot valgus and is called a fixed forefoot varus. Later, the valgus alignment of the calcaneus through the subtalar joint becomes contracted and irreducible.

 

Rarely, a secondary failure of the deltoid ligament along the medial aspect of the hindfoot develops as the mechanical stresses placed on it by the flattened arch increase. This is called a stage IV deformity.

 

Achilles tendon contracture is commonly seen in association with PTTD. As the planovalgus deformity develops, the foot collapses through the arch and the Achilles is no longer stretched to its normal length in a standing or walking posture.

 

Table 1 details the PTTD stages.

 

PATIENT HISTORY AND PHYSICAL FINDINGS

 

Most, but not all, patients present with pain along the medial arch.

 

In some cases, lateral impingement develops as the valgus posture of the hindfoot becomes extreme. The calcaneus

 

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impinges against the inferior border of the fibula. This is usually a late finding and is often intractable to conservative management.

 

 

 

FIG 1 • The accessory navicular (arrows) may be subtle and can usually be seen on the lateral or AP radiographs. To better visualize the accessory navicular and external oblique, radiograph should be obtained.

 

 

Table 1 Stages of Posterior Tibial Tendon Dysfunction

Stage Description

I

Tenosynovitis and tear without arch collapse

II

Tenosynovitis and tear with flexible deformity

III

Fixed deformity present

IV

Additional deltoid ligament insufficiency with tibiotalar tilt

 

 

The most painful phase of PTTD is usually as the tendon is actively degenerating. Some patients will note a history of intense pain that diminishes once the tendon finally ruptures completely. They may present with deformity or lateral pain as their primary complaint.

 

 

Other deformities may coexist, most significantly hallux valgus or midfoot arthritis. Methods for examining the foot for PTTD include the following:

 

The single-leg toe rise. The examiner should note the ability to perform the maneuver, the presence of inversion, and the presence or absence of pain. This is a critical and sensitive screening test. Action of the posterior tibialis is required to invert and lock the hindfoot, allowing the foot to act as a rigid lever through which the Achilles powers the ankle into plantarflexion.

 

The “too many toes” sign. The examiner observes the standing patient from behind. The more abducted forefoot will show more toes visible on the lateral side of the leg. The examiner also notes the presence of forefoot abduction. Abduction of the forefoot occurs as the posterior tibialis fails and must be corrected in treatment.

 

Power of the posterior tibialis. The examiner isolates the tendon by resisted inversion past the midline with the foot held in plantarflexion. Typical muscle strength grading is used. The result can be normal early in the disease. The patient may attempt to substitute the anterior tibialis; it is also an invertor but will dorsiflex the ankle as well.

 

Fixed forefoot varus. The examiner holds the calcaneus in a neutral position (out of valgus) and notes any fixed elevation of the first ray relative to the fifth. The severity of deformity is noted in degrees. Fixed forefoot varus must be accounted for in any treatment algorithm and is usually the first component of the deformity to become rigid.

 

Achilles contracture. The examiner holds the calcaneus in a neutral position and notes dorsiflexion of the ankle, with the knee both flexed and extended (the Silfverskiöld test). The result is measured in degrees of ankle dorsiflexion. A significant Achilles contracture limits the degree of correction possible with bracing and may require surgical correction.

 

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 an accessory navicular.

 

A standing ankle mortise view should be obtained to rule out deltoid laxity (stage IV disease).

 

Magnetic resonance imaging (MRI) is not routinely necessary and may underestimate the severity of disease, but it may be useful in ruling out other pathologies. Findings of PTTD 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 (FIG 2).

 

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 flatfoot that results from 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.1

 

 

Other options that may be suitable for higher demand situations or patients with edema control problems include a hinged molded ankle-foot orthosis or a conventional double metal upright ankle-foot orthosis 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

 

Surgery is indicated when the symptoms cannot be controlled by a nonoperative means acceptable to the patient. An active patient in his or her 50s, for instance, may find the use of an Arizona brace for the remainder of his or her life to be intolerable and may choose to pursue a surgical remedy.

 

Preoperative Planning

 

The patient's size must be considered before any motionsparing tendon reconstruction in the hindfoot is considered. Although not rigorously proven in the literature, the morbidly obese patient with an acquired pes planus deformity is at greater risk to break down the repair and may be better served by a triple arthrodesis.

 

 

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FIG 2 • The talo-first metatarsal angle is drawn down the long axis of the talus and the first metatarsal on both

lateral (A) and AP (B) radiographs. Any break from a straight line demonstrates both sag and abduction of the arch. C. MRI findings may demonstrate posterior tibial tendon edema and enlargement (arrow). Physiologic, non-edematous tendon appearance is demonstrated by the homogenous black signal of the FDL and FHL tendons immediately posterior to the diseased posterior tibial tendon.

 

 

The presence of hindfoot arthritis similarly requires a fusion rather than an osteotomy and tendon reconstruction.

 

A fixed forefoot varus should be addressed, either as part of the procedure through a medial column osteotomy or by a triple arthrodesis if severe.

 

Tightness of the gastrocnemius should also be assessed to determine if a fractional lengthening of the gastrocnemius (Strayer procedure) will be required.

 

Positioning

 

The patient is positioned supine with a bolster under the ipsilateral hip. This internally rotates the leg to allow access to the lateral aspect of the calcaneus, which is addressed first. The bolster may then be removed to allow the leg to externally rotate and allow access to the medial aspect of the foot.

 

A tourniquet is applied to the thigh.

 

Approach

 

The posterior tibial tendon is débrided directly and augmented or replaced by transferring the flexor digitorum longus (FDL) to the navicular. This procedure alone was first described in the 1980s and proved quite effective at pain control in most cases, although static correction of the arch was minimal.2,5

 

A medial displacement calcaneal osteotomy is then used to provide a measure of arch correction, directly addressing the hindfoot valgus. Indirectly, this raises the sag along the medial column of the foot as well and helps correct the talofirst metatarsal angle. Correcting the mechanics of the arch is thought to confer an

element of protection to the FDL transfer.3,8,9,11

 

If necessary, up to about 20 degrees of forefoot varus may be corrected by a plantarflexion osteotomy of the medial column through the medial cuneiform (the Cotton procedure). This allows the indications for a motionsparing procedure to be expanded to a wider patient population, and the need for this step is assessed after

the other components of the correction are complete.4

 

Once the arch is corrected, a final check of the tightness of the gastrocsoleus complex is made to ensure that a lengthening is not required.

 

 

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TECHNIQUES

• Medial Displacement Calcaneal Osteotomy

Make a 4-cm oblique incision over the lateral aspect of the calcaneal tuberosity behind the peroneal sheath (TECH FIG 1A).

Carefully avoid the sural nerve during dissection down to the periosteum (TECH FIG 1B).

Pass a small elevator above and below the calcaneal tuberosity. Ensure that inferiorly the cut will be anterior to the origin of the plantar fascia.

Place small retractors superiorly and inferiorly, and place a lowprofile self-retainer in the center of the

 

wound.

 

Use a narrow microsagittal saw to cut the tuberosity from lateral to medial. Using a narrow handheld blade provides greater tactile feedback to avoid overpenetration on the medial side (TECH FIG 1C).

 

 

 

TECH FIG 1 • A. Oblique incision for the calcaneal osteotomy. B. Careful dissection to the periosteum is made, avoiding the sural nerve. C. Dorsal and plantar retractors are placed and a microsagittal saw is used to make the cut. D. A Cobb elevator is used to free up the osteotomy. E. A lamina spreader is placed to provide further stress relaxation of the tissues. F. After displacement, retrograde screws are used to provide fixation. (continued)

 

 

Lever the osteotomy free with a large osteotome or elevator.

 

Place a lamina spreader in the osteotomy and leave it for about 1 minute to allow for stress relaxation of the tissues on the medial side. If necessary, a Cobb elevator can be used to gently strip the area (TECH FIG 1D,E).

 

Displace the tuberosity fragment medially, usually by about 1 cm. Fix it with one or two 5.0- to 6.5-mm screws placed percutaneously from the posterior tuberosity (TECH FIG 1F).

 

Obtain lateral and axial calcaneal fluoroscopy shots to confirm displacement of the tuberosity and confinement of the screws within bone.

 

With a rongeur, smooth any sharp step-off on the lateral side of the osteotomy (TECH FIG 1G,H).

 

 

00

 

 

 

TECH FIG 1 • (continued) G. The sharp margin of the osteotomy is impacted to form a smooth contour. H.

Radiographic appearance after fixation with two 5.0 screws.

• Posterior Tibial Tendon Débridement and Flexor Digitorum Longus Transfer

   

  Make a longitudinal incision down the medial column of the foot, beginning behind the medial malleolus, passing over the navicular tuberosity, and following the inferior border of the first metatarsal (TECH FIG 2A).

   

  Open the posterior tibialis sheath and débride the tendon. Complete tendon resection is appropriate in the vast majority of cases, as any remaining diseased tendon is a potential source of pain. Leave roughly a 1-cm stump of tendon attached to the navicular tuberosity to facilitate reconstruction (TECH FIG 2B).

   

   

   

  TECH FIG 2 • A. A longitudinal incision is made along the posterior tibialis sheath and medial midfoot. B.

  The posterior tibialis is found to be completely deficient and is débrided. C. The FDL sheath is opened proximally behind the posterior tibialis sheath. (continued)

   

   

  Identify the FDL sheath and open it just below the medial malleolus. It is located inferior to the posterior tibialis sheath and lies superficial to the sustentaculum tali (TECH FIG 2C).

   

  Trace the FDL sheath distally to about 2 to 3 cm distal to the navicular tuberosity. To achieve this, develop the plane between the abductor hallucis and the first metatarsal periosteum and take down a portion of the tendinous origin of the flexor hallucis brevis. This reveals the decussation of the flexor hallucis longus (FHL) and FDL, also called the knot of Henry (TECH FIG 2D).

   

  01

   

   

   

  TECH FIG 2 • (continued) D. The FDL is followed and exposed to the knot of Henry. E. A distal tenodesis of the FDL and FHL is made; the FDL is then cut. F. A dorsal to plantar drill hole is made in the navicular tuberosity. G. Placing a sucker tip to suck the sutures through the drill hole allows for easy passage. H. The FDL is passed through the navicular from plantar to dorsal. I. The FDL is turned back on itself and sutured in place, and the spring ligament is repaired.

   

  The FDL is optionally tenodesed to the FHL at the distal aspect of the incision and any evident juncturae between the two tendons are resected. Although small toe function is theoretically aided by this tenodesis, there appears to be little clinically recognizable effect from its omission (TECH FIG 2E).

   

  Drill a 4- to 5-mm hole through the navicular tuberosity and apply a lead stitch to the FDL tendon. Pass it through the hole from plantar to dorsal and suture it into the deep periosteum at both entrance and exit. If possible, pass it back upon itself. Hold the foot in about 20 degrees of equinus and 20 degrees of inversion during this maneuver (TECH FIG 2F-I).

   

  Any evident defects or redundancy in the plantar talonavicular ligament (spring ligament) can be imbricated at this time.

• Plantarflexion Osteotomy of the Medial Cuneiform (Cotton Procedure)

 

Make a 4-cm incision centered over the medial cuneiform. This should be a separate incision from that used for the posterior tibialis reconstruction, and usually, a 3- to 4-cm skin bridge can be achieved (TECH FIG 3A).

 

Identify the central portion of the medial cuneiform, essentially even with the base of the second metatarsal. Drive a Kirschner wire in to template the desired location of the osteotomy (TECH FIG 3B,C).

 

Use a microsagittal saw to create a transverse osteotomy through the medial cuneiform only, taking care to avoid penetrating the plantar cortex (TECH FIG 3D).

 

02

 

Hinge open the osteotomy with a small osteotome. Kirschner wires drilled on either side of the osteotomy spread with a lamina spreader can facilitate access (TECH FIG 3E,F).

 

Insert a tapered piece of graft into the osteotomy to complete the correction. A piece from the calcar of a femoral head allograft or iliac crest allograft may be used. Proximal tibial autograft is also suitable. The piece is sized depending on the degree of correction required; typically, a wedge measuring 5 to 7 mm at its base is used (TECH FIG 3G,H).

 

 

 

TECH FIG 3 • A. Residual forefoot varus is noted after the other components of the reconstruction are done. B,C. A longitudinal incision is made over the medial cuneiform and a Kirschner wire is placed to mark the center of the bone. The position is then checked fluoroscopically. D. A microsagittal saw is used to create the osteotomy, leaving the plantar cortex intact as a hinge. E. Temporary Kirschner wires are placed on either side of the osteotomy. F. A lamina spreader is used against them to lever the osteotomy open, dropping the medial column. G. A femoral head allograft is used to provide a wedge of bone, (continued)

 

 

Fixation is not usually necessary. If the graft is not felt to be stable, a dorsal three-hole 2.0- or 2.4-mm plate can be contoured to fit (TECH FIG 3I,J).

 

03

 

TECH FIG 3 • (continued) which (H) typically measures 5 to 7 mm at its base. I,J. After impaction of the allograft, the medial column has been plantarflexed and the forefoot varus has been corrected.

 

 

 

PEARLS AND PITFALLS

Indications

• Excessive forefoot varus (>30 degrees) cannot be accommodated.

• Hindfoot arthritis must be carefully ruled out using weight-bearing films.

Medial

displacement calcaneal osteotomy

• The sural nerve must be carefully protected; sural neuritis is a common

  issue postoperatively.

• Avoid placing the osteotomy cut too far posteriorly into the origin of the plantar fascia.

• Adequate displacement is achievable, only if the tuberosity can be adequately distracted before attempting the medial shift.

• Confirm screw placement with an axial fluoroscopic image.

Posterior tibial

tendon reconstruction

• Have a low threshold for complete resection of the posterior tibial tendon.

• Be prepared for vascular perforators overlying the approach to the knot of Henry.

• Suture anchors may provide a salvage if the FDL is harvested too short or if tunnel problems occur.

Cotton osteotomy

• Be sure the osteotomy will be parallel to the first tarsometatarsal joint by

  checking the templating Kirschner wire position on the lateral fluoroscopic image.

• Slight overcorrection is usually well tolerated.

 

 

POSTOPERATIVE CARE

 

A bulky postoperative splint is initially applied.

The patient is transferred to a removable boot at 10 to 14 days and allowed gentle active foot motion only.

Weight bearing may commence at 1 month for the calcaneal osteotomy alone, 6 weeks if a cuneiform osteotomy has been performed.

Physical therapy for hindfoot motion and posterior tibialis strengthening commences with weight bearing and is continued for at least 6 weeks. Thera-Band exercises are particularly useful.

Regular shoe wear is initiated at 2.5 to 3 months depending on swelling. Postoperative compression stockings may be useful in some patients.

Patients should be warned that the full effect of surgery may take up to 1 year to occur. This time is required for the small cross-sectional area of the transferred FDL tendon to hypertrophy into its new expanded role.

 

OUTCOMES

Initial reports of FDL transfer with posterior tibialis débridement alone demonstrated excellent pain relief but little lasting correction of the arch.2,5

The FDL transfer in combination with a calcaneal osteotomy has demonstrated lasting radiographic arch correction and the functional ability to perform a single-leg toe rise. Three-year to 5-year follow-up studies have shown success rates of 90% or greater.3,8,9,11

Long-term follow-up of the medial cuneiform osteotomy in this setting is not yet available. One short-term study detailing its use in a variety of foot deformity corrections in adults demonstrated no nonunions in 16 feet.4

Dramatic hypertrophy of the FDL muscle occurs over the first year after transfer.10 No clinical difference in ultimate strength has been noted between patients in whom the diseased posterior tibialis was excised versus débrided and retained.

 

 

04

 

COMPLICATIONS

Sural nerve injury

Navicular tunnel failure or early FDL pullout

Hardware tenderness from the posterior calcaneal screws Nonunion

Deep venous thrombosis

 

 

REFERENCES

1. Augustin JF, Lin SS, Berbarian WS, et al. Nonoperative treatment of adult acquired flat foot with the Arizona brace. Foot Ankle Clin 2003;8:491-523.

    

2. Funk DA, Cass JR, Johnson KA. Acquired adult flat foot secondary to posterior tibial tendon pathology. J Bone Joint Surg Am 1986;68(1):95-102.

    

3. Guyton GP, Jeng C, Krieger LE, et al. Flexor digitorum longus transfer and medial displacement calcaneal osteotomy for posterior tibial tendon dysfunction: a middle-term clinical follow-up. Foot Ankle Int 2001;22:627-632.

    

    

4. Hirose CE, Johnson JE. Plantarflexion opening wedge medial cuneiform osteotomy for correction of fixed forefoot varus associated with flatfoot deformity. Foot Ankle Int 2004;25:568-574.

    

    

5. Mann RA, Thompson FM. Rupture of the posterior tibial tendon causing flatfoot: surgical treatment. J Bone Joint Surg Am 1985;67(4): 556-561.

    

    

6. Mosier SM, Pomeroy G, Manoli A II. Pathoanatomy and etiology of posterior tibial tendon dysfunction. Clin Orthop Relat Res 1999;365:12-22.

    

    

7. Myerson M, Solomon G, Shereff M. Posterior tibial tendon dysfunction: its association with seronegative inflammatory disease. Foot Ankle 1989;9:219-225.

    

    

8. Myerson MS, Badekas A, Schon LC. Treatment of stage II posterior tibial tendon deficiency with flexor digitorum longus tendon transfer and calcaneal osteotomy. Foot Ankle Int 2004;25:445-450.

    

    

9. Myerson MS, Corrigan J. Treatment of posterior tibial tendon dysfunction with flexor digitorum longus tendon transfer and calcaneal osteotomy. Orthopedics 1996;19:383-388.

    

    

10. Rosenfeld PF, Dick J, Saxby TS. The response of the flexor digitorum longus and posterior tibial muscles to tendon transfer and calcaneal osteotomy for stage II posterior tibial tendon dysfunction. Foot Ankle Int 2005;26:671-674.

     

     

11. Wacker JT, Hennessy MS, Saxby TS. Calcaneal osteotomy and transfer of the tendon of flexor digitorum longus for stage-II dysfunction of tibialis posterior: three- to five-year results. J Bone Joint Surg Br 2002;84(1):54-58.