Arthrodesis is indicated for the management of an acquired adult flatfoot
disorder with a fixed deformity or degenerative joint disease. In general,
limited fusions of the hindfoot and midfoot preserve more motion than do
extensive fusion procedures such as triple arthrodesis. However, full
correction of the deformity is important for a durable outcome, and this may
require a more extensive fusion procedure or the inclusion of adjunctive
procedures.
Triple arthrodesis provides the most reliable and predictable correction of
a fixed deformity. Careful preoperative and intraoperative physical
examination and radiographic evaluation are critical to developing an
operative plan that will address all of the components of this complex
deformity and to minimizing the chance of its recurrence.
Posterior tibial tendon dysfunction is the most common etiology of adult
acquired flatfoot deformity. The pathological process by which this
dysfunction occurs varies and may be inflammatory, degenerative, or traumatic
in nature. Acquired adult flatfoot deformity can occur in younger patients
(thirty to forty years old) with inflammatory arthropathy, but it is more
common in older women (fifty to sixty years old) with degenerative
tears1. Posterior
tibial tendon dysfunction with loss of the dynamic stabilizer of the medial
aspect of the hindfoot can lead to a progressive valgus deformity of the
hindfoot. Once the posterior tibial tendon ruptures or becomes elongated, the
dynamic forces of weight-bearing contribute to attritional rupture or laxity
of the static hindfoot stabilizers and collapse of the medial longitudinal
arch. There is sagging of the medial column of the foot with eversion and
external rotation of the calcaneus in relation to the talus. With
longer-standing deformity, compensatory forefoot varus often develops
(Figs. 1-A and 1-B).
Johnson and
Strom2 described
three clinical stages of posterior tibial tendon dysfunction (Stages I, II,
and III). This staging system was subsequently modified to include Stage IV,
or the so-called tilted-ankle deformity, which indicates valgus tilt of the
talus in the ankle
mortise1.
Surgical intervention is indicated following failure of nonoperative
treatment. The surgical management of a flexible flatfoot without degenerative
changes has been reviewed in detail
elsewhere1,3-6.
Every attempt should be made to fully correct the deformity with hindfoot
osteotomies, midfoot osteotomies, soft-tissue balancing, and tendon transfers
in order to fuse as few joints as possible; however, full correction of the
deformity may necessitate fusion of one or more joints. Although there is
controversy about whether full correction of the deformity is absolutely
necessary for a good
outcome7, residual
hindfoot valgus deformity following hindfoot fusion with only partial
correction will lead to substantially increased valgus stresses at the ankle
and may result in late valgus deformity of the tibiotalar joint. Stage-II
disease with degenerative changes, Stage-III disease, and Stage-IV disease
generally require an arthrodesis of some type. The management of a Stage-IV
foot deformity is similar to that of a Stage-II or III deformity, depending on
the degree of arthritis and the flexibility of the hindfoot. The valgus ankle
component of a Stage-IV disorder has been managed with a variety of
techniques, including reconstruction of the deltoid ligament, ankle fusion,
total ankle replacement, and bracing. Management of this component is not the
focus of this paper.
Painful joints with modest-to-severe degenerative changes must be treated
with arthrodesis in order to minimize residual postoperative pain. Arthrodesis
can be avoided when painful joints have minimal degenerative changes since
such joints often become painless after repositional osteotomies and tendon
transfers alone. Arthrodeses for acquired adult flatfoot deformity include
subtalar, double, triple, tibiotalocalcaneal, and pantalar procedures. Limited
arthrodesis, involving the talonavicular and calcaneocuboid joints, or
isolated subtalar fusion allows more residual motion than does triple
arthrodesis8.
Severe, fixed deformities of the hindfoot and forefoot (Stage III) require
triple arthrodesis. Occasionally, triple arthrodesis alone may not fully
correct the deformity; adjunctive procedures may be necessary to correct
residual forefoot varus, forefoot abduction, or hindfoot valgus deformities
after the repositional triple arthrodesis. Adjunctive procedures include
medial displacement calcaneal osteotomy to address residual hindfoot valgus;
medial column procedures such as a plantar flexion osteotomy of the medial
cuneiform, fusion of the first tarsometatarsal joint, or naviculocuneiform
fusion to address residual forefoot varus deformity; and lateral column
lengthening to address forefoot abduction. These procedures are best performed
simultaneously with the triple arthrodesis, but they may be utilized later to
correct a malunited or incompletely corrected planovalgus foot.
In general, the proper selection of surgical procedures depends on the
severity and flexibility of the deformity as well as the presence and location
of degenerative changes about the foot and ankle. Activity level, age, body
habitus, and medical comorbidities need to be considered as well. Surgical
goals include relief of pain, establishment of a stable plantigrade foot
without the need for bracing, and maintenance of the integrity of adjacent
unfused joints, especially the ankle joint. This review will focus on the
indications, surgical techniques, and complications of the various arthrodesis
procedures used for the management of Stage-II disease with degenerative
changes and Stage-III disease.
In Stage-II disease, the deformity is flexible, and hindfoot osteotomies
are usually performed because they spare the important hindfoot joints and are
a powerful means with which to correct a wide range of deformities. Limited
arthrodesis may be indicated, especially when there is a moderate deformity
that cannot be fully corrected with reconstruction of the posterior tibial
tendon and joint-sparing osteotomy alone. Limited fusions are especially
useful when the deformity is flexible and there is evidence of arthrosis in
the hindfoot. According to Mann and Beaman, talonavicular arthrodesis is
indicated for management of an unstable talonavicular joint associated with a
flexible subtalar joint in patients who are older than fifty years of age,
whereas double arthrodesis is preferred for an unstable talonavicular joint
associated with a flexible subtalar joint in a younger
patient9. Isolated
arthrodesis of the subtalar joint is indicated for a fixed deformity of the
subtalar joint associated with a flexible forefoot as well as for a flexible
hindfoot deformity in the presence of degenerative changes in the subtalar
joint. Subtalar fusion is also indicated for salvage of a failed
reconstruction of a foot with acquired adult flatfoot deformity when there is
residual subluxation, degenerative changes, or pain at the subtalar joint. The
addition of a flexor digitorum longus tendon transfer to the navicular or the
first cuneiform has been advocated to improve function and stabilize the
talonavicular joint even when an isolated subtalar joint fusion is being
performed10.
Patients with Stage-III disease require a more extensive repositional
arthrodesis in order to fully correct the fixed deformity. Triple arthrodesis
is indicated for a rigid subtalar joint and a fixed varus deformity of the
forefoot. It may be necessary to include adjunctive procedures to fully
correct all components of the deformity. The decision to utilize these
adjunctive procedures is highly dependent on the degree of deformity and the
intraoperative assessment of the correction obtained with the initial
realignment. After reducing the subtalar, calcaneocuboid, and talonavicular
joints, the surgeon should determine whether the foot will be plantigrade. The
heel should be evaluated for excessive residual hindfoot valgus, which, if
present, may require additional correction with a medial displacement
calcaneal osteotomy. The position of the forefoot relative to the hindfoot
should be evaluated as well. Additional surgery, such as a lateral column
lengthening with a bone block placed in the calcaneocuboid joint, may be
indicated to fully correct the abducted forefoot to a neutral position. Any
residual varus deformity of the forefoot needs to be corrected
(Figs. 2-A and 2-B). This may
require an osteotomy of the medial column, such as a plantar flexion osteotomy
of the medial cuneiform, or an extended arthrodesis of the medial column.
At our institution, most of these procedures are performed with the patient
under general anesthesia and with preemptive ankle block regional anesthesia.
Antibiotic prophylaxis, a pneumatic tourniquet, and fluoroscopy are used
routinely. Patients are initially cared for in the hospital and then are
discharged on the day following the surgery. Splints and sutures are removed
and a cast is applied in the clinic at approximately two weeks
postoperatively.
Medial Column Arthrodesis
Loss of the medial longitudinal arch may be due to pathological changes in
the talonavicular, naviculocuneiform, and/or metatarsocuneiform joints.
Instability or hypermobility, degenerative changes, or residual forefoot varus
at these joints are the primary indications for medial column
fusion11. Isolated
arthrodesis of the talonavicular joint essentially eliminates motion in the
rest of the
hindfoot8. A patient
with a flexible hindfoot deformity who has no arthrosis in adjacent joints may
be a candidate for isolated talonavicular arthrodesis; however, the specific
indications remain controversial, and nonunion rates are higher than those
following other hindfoot
fusions12. Patients
with residual hindfoot valgus, instability at multiple midfoot joints, or
ankle arthrosis may require additional procedures such as a calcaneal
osteotomy, midfoot fusions, ankle fusion, or ankle
arthroplasty13.
Arthrodesis of the naviculocuneiform joint is usually performed in conjunction
with other procedures to correct hindfoot deformity and is done when there is
residual forefoot varus secondary to severe instability or arthritis at this
joint.
Surgical Technique for Talonavicular Arthrodesis A dorsomedial
longitudinal incision is made over the talonavicular joint, along the lateral
edge of the anterior tibial tendon to the tibialis anterior tendon. The
talonavicular joint capsule is identified and is incised longitudinally.
Subperiosteal dissection exposes the remainder of the talonavicular joint. A
small lamina spreader can help distract and expose the joint. The
talonavicular articular surfaces are then débrided. The forefoot is
then reduced to the talus by adducting, plantar flexing, and pronating it.
Lateral counter pressure is applied to the medial aspect of the talar head.
Provisional fixation can be obtained with use of Kirschner wires or the guide
pins for the cannulated screw system. The hindfoot should be in 5° to
10° of valgus. It is imperative that the hindfoot not be fused in varus
and that the forefoot not be left in varus relative to the hindfoot. The
reduction should be confirmed fluoroscopically as well as clinically. Once the
reduction is deemed to be satisfactory, two 4.5-mm cannulated screws are
placed across the talonavicular joint in a retrograde fashion. Occasionally, a
third cannulated screw can be placed percutaneously from the lateral aspect of
the navicular into the talus or a staple may be placed across the dorsal joint
line. In severely sclerotic bone, a tricortical iliac bone allograft or
autograft can be placed as a slot graft across the joint to augment the
fusion. A saw is used to cut a rectangular trough perpendicular to the joint
line. The slot graft is then impacted into the trough, spanning the joint
line. The wound is closed in the usual manner. It is important to assess the
foot for excessive heel valgus, forefoot varus, or heel-cord contracture
preoperatively. The presence of these problems signifies the need for
additional or different surgery to address them.
Postoperatively, a bulky compressive Robert Jones dressing and splint are
applied. Sutures are removed at two weeks. A short leg non-weight-bearing cast
is applied and worn for four weeks. The patient then wears a short leg
weight-bearing cast for another four to six weeks.
Outcomes and Complications
The outcomes of isolated talonavicular arthrodeses have varied in studies
reported in the literature. Harper reported that twenty-four of twenty-seven
patients treated with talonavicular arthrodesis to correct acquired adult
flatfoot deformity had a good or excellent result with no pain or pain only
with strenuous
activity14. The
correction was maintained in all patients at an average of twenty-seven months
postoperatively. Progressive arthrosis was noted in one ankle, one
calcaneocuboid joint, and three naviculocuneiform joints. In four of these
joints, the arthrosis had been present preoperatively and had progressed after
the talonavicular arthrodesis. There was one nonunion requiring revision and
one major wound problem.
Below and McCluskey reported the outcomes for fifteen of twenty-one
patients who had undergone isolated talonavicular arthrodesis for the
treatment of acquired adult flatfoot
deformity15. Twelve
patients had Stage-II posterior tibial tendon dysfunction, and nine patients
had Stage-III disease with talonavicular degenerative joint disease. Most of
the patients experienced daily pain postoperatively. Radiographic evidence of
subtalar arthrosis developed in eight patients, and twelve patients had pain
at the subtalar joint on examination. Six patients had a nonunion.
Complications of talonavicular arthrodesis include residual lateral midfoot
pain, malunion, nonunion, and the development of arthrosis at adjacent joints.
For these reasons, talonavicular fusion alone is not commonly performed for
Stage-II acquired adult flatfoot deformity.
Lateral Column Lengthening
Calcaneocuboid distraction arthrodesis or lateral column lengthening
arthrodesis has been advocated for the treatment of Stage-II posterior tibial
tendon dysfunction with dorsolateral peritalar
subluxation16.
Lengthening of the lateral column has been shown to restore the medial arch
and correct hindfoot valgus and forefoot
abduction17,18.
The decision whether to perform a lengthening osteotomy through the distal
part of the calcaneus or with distraction arthrodesis of the calcaneocuboid
joint is
controversial7,19.
Proponents of distraction arthrodesis of the calcaneocuboid joint cite the
potential for the development of degenerative changes at the calcaneocuboid
joint following osteotomy of the calcaneus as a result of increased contact
pressures at the calcaneocuboid
joint4,16-21;
however, the nonunion rate following distraction arthrodesis of the
calcaneocuboid joint is approximately 20%. Typically, if lateral column
lengthening is required as a component of the correction of a flexible
Stage-II acquired adult flatfoot deformity, a lengthening osteotomy of the
calcaneal neck with interposition of bone graft is performed. When lateral
column lengthening is needed for a Stage-III acquired adult flatfoot
deformity, distraction arthrodesis of the calcaneocuboid joint is performed
with interposition of bone graft as part of a triple arthrodesis.
Surgical Technique
A lateral longitudinal incision is made over the anterolateral aspect of
the calcaneus from just anterior to the tip of the fibula toward the base of
the fourth metatarsal. Dissection through the soft tissues is performed to
expose the extensor digitorum brevis, with care taken to avoid injury to the
anterior branch of the sural nerve. Other cutaneous nerves, such as the
intermediate branch of the superficial peroneal nerve, can occasionally enter
the surgical field, and they need to be protected. The peroneal tendons and
sural nerve are retracted inferiorly. The extensor digitorum brevis is
retracted superiorly; the extensor digitorum brevis origin and the plantar
aspect of the muscle may be elevated to facilitate exposure of the
calcaneocuboid joint.
The articular surfaces of the calcaneocuboid joint are then
débrided. A lamina spreader without teeth is used to distract the
joint.
Care must be taken to avoid over-correcting the heel into varus or pushing
the forefoot into varus. A tricortical iliac crest bone allograft or autograft
is then fashioned to fit into the distracted calcaneocuboid joint. This graft
usually measures between 8 and 12 mm in
width16. Fixation
is obtained with a 4.0 or 4.5-mm cannulated screw inserted in a retrograde
direction. However, an isolated distraction arthrodesis of the calcaneocuboid
joint usually requires additional fixation to help prevent a nonunion, and a
lateral plate is often added. The extensor digitorum brevis is reapproximated,
and the skin is closed in the usual manner. Postoperative care is similar to
that described above.
Outcomes and Complications
Complications of calcaneocuboid arthrodesis include cutaneous neuroma of
the sural or superficial peroneal nerve, residual lateral midfoot pain,
malunion, nonunion, and the development of arthrosis at adjacent joints.
Symptomatic nonunion is treated with bone-grafting and plate, screw, or staple
fixation. Chi et al. reported that eight of forty-one attempted distraction
arthrodeses of the calcaneocuboid joint in thirty-six patients did not result
in healing18.
Distraction arthrodesis of the calcaneocuboid joint causes some loss of motion
in the foot, but less than is seen after subtalar or talonavicular
arthrodesis21.
Isolated Subtalar Arthrodesis with Flexor Digitorum Longus
Transfer
There is support in the literature for the use of isolated subtalar
arthrodesis to treat acquired adult flatfoot deformity when the patient has a
fixed deformity of the subtalar joint and a flexible
forefoot22,23.
Mann et al. stated that 10° to 15° of forefoot varus or joint
hypermobility is a contraindication to isolated subtalar joint
fusion10. In such a
situation, isolated subtalar joint arthrodesis will overload the lateral
border during gait as a result of the fixed forefoot varus. Other indications
for isolated subtalar joint arthrodesis include degenerative changes in the
subtalar joint and salvage of a failed hindfoot reconstruction. The procedure
allows residual motion at the talonavicular and calcaneocuboid joints (26% and
56% residual motion,
respectively8). This
may have a protective effect on the development of ankle arthritis when
compared with triple
arthrodesis23.
However, the authors of an in vitro biomechanical study concluded that
isolated subtalar or calcaneocuboid fusion cannot achieve full correction of a
moderate flatfoot deformity with substantial transverse tarsal joint laxity;
in contrast, a talonavicular, double, or triple arthrodesis completely
corrected the
deformity24. We
believe that, when an isolated subtalar fusion is performed to treat acquired
adult flatfoot deformity, the addition of a flexor digitorum longus transfer
helps to support the talonavicular joint and balances the pull of the peroneus
brevis22.
Surgical Technique
An oblique longitudinal skin incision is made from the tip of the lateral
malleolus toward the base of the fourth metatarsal, centered over the sinus
tarsi. Alternatively, an oblique Ollier-type incision can be used, but this
may limit the placement of a calcaneal osteotomy incision if one is needed
during the procedure. Care is taken to preserve full-thickness skin flaps as
well as the sural nerve at the inferior and distal aspect of the incision.
The origin of the extensor digitorum brevis muscle and the peroneal tendon
sheath are identified. The origin of the extensor digitorum brevis is split in
line with the muscle fibers and is retracted superiorly. The fat in the sinus
tarsi is either excised or reflected to improve exposure. The calcaneocuboid
joint capsule is not violated. The peroneal tendons are retracted posteriorly
to expose the posterior facet of the subtalar joint. A small lamina spreader
can be inserted into the sinus tarsi to distract the subtalar joint and
improve visualization. Any obvious osteophytes should be resected, and any
removed bone should be morcellized for bone graft. The talocalcaneal
interosseous ligament is resected to allow greater distraction of the joint.
The medial aspect of the subtalar joint capsule may be excised carefully with
a rongeur if necessary to improve hindfoot mobility in order to allow
reduction.
The articular surfaces of the subtalar joint are débrided. Care
should be taken to preserve the subchondral contour of the joint surfaces in
order to maximize the surface area of bone contact. The calcaneocuboid
articulation, talonavicular articulation, and tibiotalar capsules should be
preserved.
The posterior tibial tendon is then exposed through a medial incision and
is débrided as needed. The flexor digitorum longus tendon is dissected
distal to the knot of Henry and is divided just proximal to its decussation
with the flexor hallucis longus tendon. A 4.5-mm drill hole is placed in the
navicular tuberosity, and the flexor digitorum longus tendon is pulled up from
plantar to dorsal through the drill hole with use of a grasping suture placed
in the end of the tendon. Tensioning of the flexor digitorum longus is delayed
until the subtalar joint is fused.
The subtalar joint is then reduced; this usually requires internal rotation
and inversion of the calcaneus back under the talus
(Fig. 3) as well as elevation
of the lateral column and depression of the medial column of the forefoot. The
reduction can be aided by placing a lamina spreader between the lateral
process of the talus and the anterior process of the calcaneus as described by
Hansen25 (Figs.
4 and
5). After reduction, the heel
should be in no more than 5° to 10° of valgus. Bone apposition is
confirmed, and the need for bone graft is assessed.
A small stab wound is made in the heel. Guide wires for one or two 6.5-mm
cannulated screws are introduced through the stab wound and then advanced
through the calcaneus and into the talar body under fluoroscopic control.
Proper pin placement must be confirmed on all three intraoperative
views—i.e., the lateral and anteroposterior views of the ankle and the
axial view of the heel. The cannulated screws are then inserted in the usual
manner. Stability of the construct is verified, and bone graft, if needed, is
placed after thorough irrigation of the wound with saline solution. The
addition of a flexor digitorum longus tendon transfer to the navicular or the
first cuneiform has been advocated to improve function and stabilize the
talonavicular joint even when an isolated subtalar joint fusion is being
performed10. The
flexor digitorum longus tendon is pulled up through the hole in the navicular
under moderate tension and is secured back on itself or to the surrounding
periosteum with nonabsorbable sutures. Any tears in the spring ligament
complex are also repaired.
Prior to wound closure, the extensor digitorum brevis is reapproximated
with 2-0 Vicryl sutures. Postoperative care is as described above.
Outcomes and Complications
Outcomes of subtalar joint arthrodesis for the treatment of acquired adult
flatfoot deformity have been described in the literature. Johnson et al.
reported on seventeen feet treated with subtalar joint arthrodesis,
reconstruction of the flexor digitorum longus, and repair of the spring
ligament22. At two
years postoperatively, the results compared favorably with those of medial
displacement calcaneal osteotomy and lateral column lengthening. Kitaoka and
Patzer reported sixteen good or excellent results at three years following
subtalar joint realignment and arthrodesis in twenty-one
feet23.
Complications included symptomatic arthrosis of adjacent joints, malunion, and
nonunion. Others have recommended the addition of a flexor digitorum longus
transfer to the navicular in order to help stabilize the talonavicular joint
when isolated subtalar arthrodesis is performed for Stage-II
disease22. The
addition of the flexor digitorum longus transfer in the treatment of Stage-II
disease may also help to prevent the progressive development of valgus tilt of
the ankle after triple arthrodesis, but it has not been widely utilized in
that setting.
Double Arthrodesis (Calcaneocuboid and Talonavicular Joints)
A double arthrodesis involves fusion of the calcaneocuboid and
talonavicular joints. It is indicated for a flexible moderate hindfoot
deformity with a forefoot varus deformity. It has been stated that a double
arthrodesis is indicated for a younger patient with a flexible hindfoot
deformity and excessive forefoot varus, whereas an isolated talonavicular
fusion is indicated for an older patient with that
condition26. Given
that the range of motion of the subtalar joint is essentially eliminated
following double arthrodesis, a triple arthrodesis should be performed if
there is tenderness or degenerative changes in the subtalar
joint8.
Surgical Technique
The approach to the talonavicular joint is performed as described above.
The calcaneocuboid joint is approached in a fashion similar to that described
for a calcaneocuboid distraction arthrodesis. In order to correct a major
forefoot varus deformity, care must be taken to débride enough of the
talonavicular and calcaneocuboid joints to allow derotation of the forefoot
and correction of forefoot varus. Because the talonavicular joint is at the
apex of the deformity, most surgeons reduce and stabilize it first. Guide pins
for the 4.5-mm cannulated screws can be used for provisional fixation. It is
then verified that the talonavicular joint and the calcaneocuboid joint have
been reduced simultaneously, and these joints are provisionally stabilized
with either Steinmann pins or guide pins for the cannulated screws. The
alignment of the foot and the position of the hardware are confirmed both
clinically and fluoroscopically. The talonavicular joint is then fixed with
two 4.5-mm cannulated screws; the calcaneocuboid joint is also fixed
internally, either with a screw or staples. The skin is closed in the usual
manner. Postoperative care is similar to that described above.
Outcomes and Complications
Clain and Baxter reported four excellent, eight good, and four fair results
at an average of eighty-three months after double arthrodeses performed on
sixteen feet with a variety of hindfoot
disorders24. There
was one nonunion of the talonavicular joint, which remained asymptomatic.
Progressive degenerative changes developed in the ankle of six patients and in
the naviculocuneiform joints of seven. The authors concluded that double
arthrodesis was better than isolated talonavicular fusion and a viable
alternative to triple arthrodesis.
Mann and Beaman reported the outcomes of twenty-four double arthrodeses at
an average of fifty-six
months9. Sixteen of
the double arthrodeses were performed for acquired adult flatfoot deformity
due to posterior tibial tendon insufficiency, and eight were done for other
diagnoses. Similar outcomes were observed in the two groups of patients, with
eighteen patients having a good or excellent result overall. Complications
were more frequent in the patients who had flatfoot deformity. Talonavicular
nonunion was the most frequent complication, occurring in four patients, three
of whom required revision arthrodesis. The development of arthrosis in the
surrounding joints was common but asymptomatic. For this reason, triple
arthrodesis may be preferred for most patients.
Triple Arthrodesis
Triple arthrodesis is indicated for the treatment of acquired adult
flatfoot deformity when the subtalar joint or transverse tarsal joint is not
passively correctable, when there are degenerative changes at the subtalar
joint or transverse tarsal joint, and for the salvage of a failed hindfoot
reconstruction. The radiographic criteria for triple arthrodesis are
controversial and are of limited
value27. Myerson
recommended triple arthrodesis for a fixed hindfoot deformity with subfibular
impingement1. Others
have stated that medial foot pain associated with dorsal peritalar subluxation
should be corrected with triple
arthrodesis28. The
goal of triple arthrodesis is to fuse the subtalar, talonavicular, and
calcaneocuboid joints with the hindfoot in 5° of valgus and to correct
midfoot and forefoot deformities to neutral through repositional arthrodesis.
A single extensile lateral or extensile medial incision could be used if
needed for access to the joint in a triple arthrodesis, but a two-incision
technique provides better exposure and allows easier correction of the
deformity.
Surgical Technique
Two incisions are utilized for this procedure. The lateral incision is made
obliquely from the tip of the distal part of the fibula to the base of the
fourth metatarsal. Occasionally, branches of the intermediate branch of the
superficial peroneal nerve may cross the surgical field near the anterior
aspect of the calcaneus. If they do, these branches are identified and are
retracted cephalad. The subcutaneous exposure involves creation of
full-thickness flaps with meticulous soft-tissue handling. Care should be
taken to identify and protect the sural nerve and any branches of the
superficial peroneal nerve.
The peroneal tendons are identified and retracted. The extensor digitorum
brevis is incised along its muscle fibers and is sharply raised from the
calcaneal insertion. The subtalar joint is exposed as described above. The
lateral talonavicular, calcaneocuboid, and naviculocuboid articulations are
identified. A useful landmark for localizing the talonavicular joint is the
insertion of the bifurcate ligament (ligament of Chopart). The bifurcate
ligament consists of the lateral calcaneonavicular and medial calcaneocuboid
ligaments and inserts into the calcaneonaviculocuboid region. The lateral
aspect of the calcaneus is followed distally to the calcaneocuboid joint. The
calcaneocuboid joint capsule is incised sharply both laterally and dorsally.
The lateral aspect of the talonavicular joint may then be partially exposed
and débrided through the lateral incision. The naviculocuboid
articulation is débrided in a similar manner. Exposure of the
calcaneocuboid joint can be facilitated by use of a small lamina spreader. The
articular surfaces of the calcaneocuboid joint are then débrided. The
articular surfaces of the subtalar joint are prepared as described above.
The dorsomedial approach, as described above, is used to expose the
remainder of the talonavicular joint and allow complete débridement of
the talonavicular joint. The foot is placed into a plantigrade position. After
the hindfoot is corrected to the "anatomic neutral" position, the
necessity for adjunctive procedures should be assessed. A tendo Achillis
lengthening is almost always required and is usually performed at the outset
of the procedure before the surgeon tries to reposition the foot. If there is
residual heel valgus of >5° to 10° after subtalar joint alignment
has been re-established, a medial displacement calcaneal osteotomy may be
needed. Next, the position of the forefoot relative to the hindfoot needs to
be considered since residual forefoot varus promotes a valgus thrust on the
hindfoot with gait and may contribute to a poor outcome and late valgus
deformity at the ankle secondary to insufficiency of the deltoid ligament. If
the forefoot is abducted, distraction arthrodesis of the calcaneocuboid joint
may be required. The medial column is evaluated for instability or any
residual supination deformity that might require fusion of the first
tarsometatarsal joint, plantar flexion cuneiform osteotomy, or
naviculocuneiform fusion.
Intraoperatively, the decision to begin with reduction of the subtalar
joint or the talonavicular joint is
controversial7.
Proponents of primary subtalar joint fusion cite the ability and importance of
placing the hindfoot in slight valgus with subsequent reduction of the
forefoot by lateral column lengthening or medial column
arthrodesis25.
Primary fixation of the talonavicular joint is favored by those who believe a
multiplanar correction of the talonavicular joint will reduce the rest of the
deformity24. We
prefer correcting the deformity in a proximal-to-distal progression, beginning
with the subtalar joint. Once the heel is in neutral, the midfoot is reduced
at the talonavicular and calcaneocuboid joints.
After the subtalar joint is reduced in a position of 5° to 10° of
valgus, inspection should confirm that the heel was not placed in varus.
Several maneuvers to assist reduction have been described. A lamina spreader
placed in the sinus tarsi between the calcaneus and the lateral talar process,
or neck, can be used to push the forefoot out of abduction and effectively
lengthen the lateral column, rather than distract the subtalar
joint25 (Figs.
4 and
5). Alternatively, primary
talonavicular reduction can be achieved by pushing the head of the talus
laterally while adducting and pronating the
forefoot29.
Kirschner-wire joysticks placed transversely across the midfoot may be helpful
for elevating the lateral aspect of the forefoot and depressing the medial
aspect of the forefoot during reduction of forefoot varus.
The reduction is confirmed fluoroscopically. Internal fixation with screws
is utilized routinely at the subtalar, talonavicular, and calcaneocuboid
joints. The guide pins for the cannulated screws can be used to provide
provisional fixation. Staple fixation with or without a screw is commonly
utilized at the calcaneocuboid joint.
A 6.5-mm cannulated screw can be inserted in either a retrograde fashion
(as described above) or an antegrade fashion (from the dorsal aspect of the
talar neck into the calcaneus) across the subtalar joint. This screw is
countersunk and is usually placed from the calcaneus to the talus in order to
avoid the neurovascular bundle. The talonavicular joint is internally fixed
with two cannulated 4.5-mm screws, approximately 40 to 50 mm long, from the
navicular tuberosity into the head and neck of the talus. Technically, it is
important to countersink the head of the screw in the navicular to minimize
hardware prominence. The calcaneocuboid articulation is internally fixed with
two 30 to 40-mm-long 4.5-mm cannulated screws or a staple device.
Postoperative care is similar to that following any arthrodesis of the
hindfoot. Initially, a bulky compressive Robert Jones dressing and splint are
applied. At two weeks, the foot is placed in a cast, which is worn for an
additional four weeks. Protected weight-bearing in a cast is begun at six
weeks. At ten weeks, a removable walker boot is applied, and the patient
gradually resumes shoe wear at twelve to fourteen weeks.
Outcomes and Complications
Outcomes after triple arthrodesis have been well
described27,29-36.
Graves et al. reported on a series of eighteen feet in seventeen patients who
had undergone triple
arthrodesis30. At
an average of 3.5 years, pain was decreased in all patients, although eleven
feet were the source of residual discomfort. A substantial prevalence of
degenerative changes in the ankle and foot was noted. The authors concluded
that triple arthrodesis is a satisfactory salvage operation but is technically
difficult an.d is associated with a relatively high complication rate. Fortin
and Walling29 and
Haddad et al.36
both noted effective pain relief and improved function at four to six years
following triple arthrodesis for deformity correction. Both concluded that
triple arthrodesis was an acceptable treatment for late-stage disease and
noted a propensity for secondary degenerative changes to develop at the ankle
joint. Similarly, in a report on the results twenty-five and forty-four years
after triple arthrodesis, Saltzman et al. reported that sixty-four of
sixty-seven feet had a satisfactory
result37. Twenty
feet had degenerative changes at the ankle at twenty-five years, and all had
degenerative changes at forty-four years. Interestingly, the radiographic
appearance of the ankle did not correlate with symptoms.
Adjunctive procedures may be necessary to fully correct a severe fixed
flatfoot deformity. The need to perform these procedures is determined by
careful preoperative and intraoperative assessment of the hindfoot alignment
and the degree of fixed varus deformity of the forefoot. Tendo Achillis
lengthening or gastrocnemius-soleus lengthening is almost always necessary to
correct the equinus contracture seen with acquired adult flatfoot deformity.
These procedures are indicated when the patient lacks 10° of ankle
dorsiflexion with the knee extended. Tendo Achillis lengthening can be
performed percutaneously or with an open technique, and gastrocnemius-soleus
lengthening is performed in the midcalf through a small medial or midline
incision. We prefer an open Z-lengthening of both the gastrocnemius and the
soleus muscle at the myotendinous junction, as this allows a more controlled
release of the gastrocnemius muscle either alone or in combination with the
soleus, depending on which is tight. However, excellent results can be
obtained with either method.
Medial displacement calcaneal osteotomy is useful for correcting residual
hindfoot valgus after initial realignment of the heel. Medial displacement
calcaneal osteotomy helps to remove the deforming force of the Achilles tendon
on the valgus heel by displacing its insertion medially. It may be used in
conjunction with a lateral column lengthening by means of calcaneocuboid
distraction arthrodesis if there is excessive residual hindfoot valgus along
with excessive forefoot abduction. The need for a medial displacement
calcaneal osteotomy can be assessed intraoperatively after provisional
reduction and fixation of the calcaneus under the talus. The surgeon can then
assess the hindfoot for any residual valgus deformity. If excessive hindfoot
valgus is noted, either repeat repositioning of the subtalar joint can be
performed if full correction was not obtained or a medial displacement
calcaneal osteotomy can be utilized to correct the residual valgus.
A plantar flexion osteotomy through the medial cuneiform is useful for
reducing residual varus forefoot deformity and restoring the weight-bearing
tripod of the foot. The osteotomy is oriented in the coronal plane through the
midportion of the medial cuneiform at the level of the second tarsometatarsal
joint (Fig. 6). The first ray
is then plantar flexed through this osteotomy site by gently levering the site
open with a small osteotome. The resulting gap in the cuneiform is measured
once the first ray is plantar flexed to a neutral position. A wedge-shaped
tricortical allograft bone block is then cut to this width. It is usually
between 4 and 7 mm thick. The graft is impacted into the osteotomy site. The
osteotomy site is secured with internal fixation with a 4.0-mm screw or a
percutaneous 0.062-inch (1.575-mm) Kirschner wire. If the forefoot varus is
secondary to instability, subluxation, or degenerative arthritis at the first
tarsometatarsal joint, reduction and fusion of this joint is performed.