In cavovarus foot deformity, the relatively strong peroneus longus and tibialis posterior muscles cause a hindfoot varus and forefoot valgus pronated position.. Etiology Neurologic The h
Trang 1Cavovarus foot deformity, which often results from an imbalance
of muscle forces, is commonly caused by hereditary motor sensory neuropathies Other causes are cerebral palsy, cerebral injury (stroke), anterior horn cell disease (spinal root injury), talar neck injury, and residual clubfoot In cavovarus foot deformity, the relatively strong peroneus longus and tibialis posterior muscles cause a hindfoot varus and forefoot valgus (pronated) position Hindfoot varus causes overload of the lateral border of the foot, resulting in ankle instability, peroneal tendinitis, and stress fracture Degenerative arthritic changes can develop in overloaded joints Gait examination allows appropriate planning of tendon transfers to correct stance and swing-phase deficits Inspection of the forefoot and hindfoot positions determines the need for soft-tissue release and osteotomy The Coleman block test is invaluable for assessing the cause of hindfoot varus Prolonged use of orthoses
or supportive footwear can result in muscle imbalance, causing increasing deformity and irreversible damage to tendons and joints Rebalancing tendons is an early priority to prevent unsalvageable deterioration of the foot Muscle imbalance can be corrected by tendon transfer, corrective osteotomy, and fusion Fixed bony deformity can be addressed by fusion and osteotomy
Cavovarus foot can present in childhood or adulthood as ei-ther progressive or fixed, depending
on the underlying cause and its se-verity Cavovarus foot deformities are categorized by etiology The four main causes of the adult cavovarus foot are neurologic, traumatic, the result of residual clubfoot, and idio-pathic (Table 1)
Etiology Neurologic
The hereditary motor and
senso-ry neuropathies (HMSNs) that cause cavus foot deformity are mostly mo-tor, rather than congenital or pro-gressive.1Muscle imbalance usually predominates in agonist-antagonist
pairs, such as a weak anterior tibial muscle with a strong peroneus lon-gus, or a weak peroneus brevis with
a strong tibialis posterior muscle Subgroups of the HMSNs have in-cluded Charcot-Marie-Tooth (CMT) disease and Dejerine-Sottas disease; however, gene analysis is rapidly changing the classification and un-derstanding of HMSNs For example,
17 variants of CMT disease have been determined with gene map-ping Subgroups now include demyelinating and axonal patholo-gies subdivided into autosomal-dominant, autosomal-recessive, and X-linked transmission groups Be-cause there is no definitive diagnos-tic technique for patients with an HMSN, the diagnosis is made based
Alastair S E Younger, MB, ChB,
MSc, ChM, FRCSC, and
Sigvard T Hansen, Jr, MD
Dr Younger is Director, Foot and Ankle
Program, Providence Health Care, and
Clinical Associate Professor, The
Division of Lower Limb Reconstruction
and Oncology, Department of
Orthopaedics, University of British
Columbia, Vancouver, BC, Canada.
Dr Hansen is Chief, Foot and Ankle
Service, and Professor and Chairman
Emeritus, Department of Orthopaedics,
University of Washington, Harborview
Medical Center, Seattle, WA.
None of the following authors or the
departments with which they are
affiliated has received anything of value
from or owns stock in a commercial
company or institution related directly or
indirectly to the subject of this article:
Dr Younger and Dr Hansen.
Reprint requests: Dr Younger,
Univer-sity of British Columbia, 401-1160
Burrard Street, Vancouver, BC V6Z 2E8
Canada.
J Am Acad Orthop Surg
2005;13:302-315
Copyright 2005 by the American
Academy of Orthopaedic Surgeons.
Trang 2on the appearance of the foot and a
positive family history
Peripheral neuropathy usually
causes weakness of the intrinsic
muscles, followed by more proximal
involvement The long flexor and
ex-tensor tendons overpower the
lum-brical and interosseus muscles,
caus-ing flexion at the interphalangeal
joints and hyperextension at the
metatarsophalangeal joints
Sublux-ation followed by dislocSublux-ation at the
metatarsophalangeal joint causes
the plantar pad to migrate distal to
the metatarsal head, bringing the
thinner, more proximal skin under
the weight-bearing metatarsal head
Proximal weakness may affect
pero-neal and tibial nerve distribution.2
Relative weakness of the anterior
tibialis and the peroneus longus
muscles causes plantar flexion of the
first ray relative to the lesser
meta-tarsal heads In time, these
deformi-ties become fixed
The combination of the
relative-ly strong tibialis posterior and
pero-neus longus muscles with the weak
peroneus brevis and tibialis anterior
muscles results in a hindfoot varus
and forefoot valgus (pronated)
posi-tion In patients with CMT disease,
the peroneus longus is
hypertro-phied with normal muscle
architec-ture, creating imbalance in relation
to the tibialis anterior muscle.3
Re-cruitment of the extensor hallucis in
the absence of a functional tibialis
anterior further drives down the first
metatarsal head via the windlass
mechanism on the medial plantar
fascia Patients also often present
with forefoot adduction and plantar
flexion of the first ray When a
sec-ondary equinus deformity develops
at the ankle, the patient with
ad-vanced involvement walks with a
high-stepping drop-foot gait with
hy-perextension of the knee Other
neu-rologic and congenital causes of
cavovarus foot include conditions
with more profound proximal
in-volvement (eg, amyotrophic lateral
sclerosis [Lou Gehrig’s disease],
Huntington’s chorea, Friedreich’s
ataxia) that often make addressing foot deformity a lower priority
Depending on the area of the mo-tor cortex involved and the resultant weakness and spasticity, patients with cerebral palsy may have a planovalgus (66%) or cavovarus de-formity (34%) (23 of 35 and 12 of 35 patients, respectively).4Mulier et al5
reported on 17 patients with tendon transfer for equinovarus Foot in-volvement in cerebral palsy varies in nature and presentation Equinus is rarely seen alone, and a varus or val-gus component is almost always as-sociated with a tight heel cord The deformity varies between the swing and stance phases of gait, particularly
in patients with a flexible deformity
Adult patients with intracerebral bleeding or closed head injury may develop subsequent equinus and equinovarus deformities The suc-cess of treatment depends on the de-gree and severity of central involve-ment Patients with poor cognition
or with extensive stroke-related motor, proprioceptive, or sensory deficits are poor candidates for re-constructive surgery In some wheelchair-bound patients, tendon releases may be indicated to assist in shoe wear or transferring or to re-solve pressure sores A delay of 18 to
24 months between cerebral injury and reconstructive surgery is advis-able because of the possibility of var-ious degrees of functional recovery
Poliomyelitis affects the anterior horn cells in the spinal cord and causes a lower motor neuron paraly-sis that affects specific spinal roots
The level of root involvement deter-mines whether patients develop a cavovarus, planovalgus, or calcaneus gait pattern Depending on the ex-tent and pattern of deformity, pa-tients with poliomyelitis may bene-fit from limited foot fusions or osteotomies as well as in-phase and out-of-phase muscle transfers
Congenital multiple arthrogrypo-sis is usually obvious by its other manifestations, resulting in a stiff fixed equinovarus foot deformity
Amyotrophic lateral sclerosis and spinal muscular atrophy also can re-sult in progressive cavovarus foot position A unilateral progressive cavovarus foot may be caused by an instrinsic spinal cord lesion In a re-view of 43 patients with diastema-tomyelia, 11 had a cavus foot and 4 had a clubfoot.6Progression of cavus foot is an indication for tethered cord release.7 Pes cavus associated with scoliosis suggests a neurologic origin for both conditions.7
Traumatic
The muscle contractures created
by deep posterior compartment syn-drome cause the tibialis posterior and the flexor digitorum longus muscles to pull the foot into an equi-nus and cavovarus position Severe scarring after burns, crush injuries,
or venous stasis may pull the foot into the cavovarus position A talar neck fracture malunion can leave the distal portion of the talar neck in
a shortened, dorsally and medially translated position, resulting in a fixed varus position of the subtalar, talonavicular, and calcaneocuboid joints.8
Four Primary Causes of Adult Cavovarus Foot
Neurologic Hereditary motor and sensory neuropathies
Cerebral palsy Aftereffects of cerebral injury (stroke)
Anterior horn cell disease (spinal root injury)
Spinal cord lesions Traumatic
Compartment syndrome Talar neck malunion Peroneal nerve injury Knee dislocation (neurovascular injury)
Residual clubfoot Idiopathic
Table 1
Trang 3Injury to the deep branch of the
peroneal nerve or to the L5 nerve
root resulting in peroneal muscle
weakness leaves the action of the
tibialis posterior and long toe flexor
muscles unopposed, causing
hind-foot and forehind-foot varus For example,
knee dislocation with permanent
in-jury to the peroneal nerve may lead
to an equinocavovarus position of
the ankle or foot, requiring multiple
tendon transfers early in treatment
Heel varus may subject the peroneus
brevis tendon to repetitive injury,
re-sulting in a degenerative tear and
possible rupture Loss of the
pero-neus brevis tendon can progress to a
significant cavovarus foot
Residual Clubfoot
The untreated or partially treated
clubfoot can result in a persisting
cavovarus and equinus position in
adults, with the foot fixed in a
char-acteristic hindfoot and forefoot
varus position Other residual
prob-lems may include an overlengthened
heel cord, causing a calcaneus gait or
restricted ankle motion secondary to
a flat-topped talus.9
Idiopathic
In some patients, an underlying
cause is not found The genetic
pat-terns of some HMSNs are still
un-known, offering promise that many
of the presently idiopathic causes
will be better understood in the
fu-ture Idiopathic peripheral
neuropa-thy is the most distressing cause of a
cavus foot, often presenting early
with neuropathic ulcers and sensory
imbalance as well as motor
involve-ment In all cases, early muscle
re-balancing by transfers and
osteoto-mies is required, as are ongoing
physiotherapy and shoe
modifica-tions
Clinical Presentation
Patients often present with pain
caused by increased stress on one
part of the foot Overload of the
cuboid region occurs with the
hind-foot and forehind-foot varus position seen
in patients with clubfoot Patients with CMT disease may overload the lateral border of the foot, the first metatarsal head,10 or the lateral metatarsal heads This increased load can cause stress fractures, most commonly in the fifth metatarsal In runners, the cavus foot position causes increased load on the meta-tarsal heads and on the calcaneus.11
The varus position of the hind-foot also may result in lateral ankle instability, with the lateral
collater-al ligaments being continuously overloaded by the medially displaced moment arm of the Achilles ten-don Symptomatic metatarsalgia is caused by distal migration of the fat pad underneath the metatarsal heads
in association with claw toe defor-mity
Prolonged weight bearing in the cavus position may cause overload
of the ankle and of the joints of the so-called triple-joint complex (ie, the subtalar, talonavicular, and calca-neocuboid joints) Secondary degen-erative change occurs in the over-loaded medial aspect of the ankle joint, often associated with varus tilt
of the talus and concomitant lateral ligament laxity
A family history of similar defor-mity indicates a hereditary cause
Spontaneous occurrence of a unilat-eral clubfoot, especially when ac-companied by other neurologic symptoms, suggests a spinal cord le-sion, necessitating additional work-up
Physical Examination
Patients should be examined while walking and standing, and limb alignment and the weight-bearing posture of the foot should be as-sessed The presence of foot drop, hyperextension of the great or lesser toes, and varus or valgus positioning
of the forefoot and hindfoot may be appreciated during the swing phase
of gait Stance phase is analyzed from heel strike to toe-off The
posi-tion of calluses should reinforce the observations of gait The range of motion of all surrounding joints should be measured The heel cord is tested for tightness with the knee both flexed and extended Lack of change in equinus deformity be-tween the two positions may indi-cate a mechanical block to ankle dorsiflexion from a tight posterior capsule or anterior osteophytes Oc-casionally, an isolated contracture of the soleus causes restriction of ankle dorsiflexion with the knee in both flexion and extension Equinus with the knee straight, and increased dor-siflexion with the knee flexed, indi-cate a tight gastrocnemius muscle Function and strength of all mus-cles and nerve roots in the region should be mapped at least twice The power or strength of each muscle is tested against active resistance ap-plied by the examiner, and the re-sults are graded using the Medical Research Council scale The grading
of muscular response in this scale ranges from 0 to 5: grade 0, no con-traction; grade 1, flicker or trace of contraction; grade 2, active move-ment with gravity eliminated; grade
3, active movement against gravity; grade 4, active movement against gravity and resistance; and grade 5, normal power Tendons are palpated
to determine whether they are a source of pain Tendon imbalance may cause dynamic deformity (eg, the peroneus longus may be
recruit-ed to compensate for a weak pero-neus brevis) The dynamic
deformi-ty causes a plantarflexed position of the first ray and an increased cavus deformity Complete neurologic examination also should include reflexes, sensation, and vibratory response
A Coleman block test should be performed to separate forefoot-driven hindfoot varus from an intrin-sic or tibialis posterior muscle– driven hindfoot varus A flexible hindfoot with a fixed plantarflexed first ray will correct with the Cole-man block test, indicating that
Trang 4cor-rection of the forefoot position
should correct the hindfoot varus
(Fig 1) Failure of the hindfoot varus
to correct indicates a fixed hindfoot
deformity that may require both a
hindfoot procedure to correct the
varus (eg, calcaneal osteotomy or
subtalar fusion) and a dorsiflexion
osteotomy of the first ray.10The
re-sults of the Coleman block test must
be interpreted in the context of the
remainder of the physical
examina-tion because a patient with fixed
hindfoot varus and a valgus position
of the forefoot still requires
correc-tion of the forefoot posicorrec-tion When
in doubt, a lateralizing calcaneal
os-teotomy should be performed
be-cause the varus deformity of the
hindfoot remains undercorrected in
all but the mildest cases
Radiographic
Evaluation
Weight-bearing anteroposterior and
lateral views of the foot and ankle
are required, along with a calcaneal
axial view Oblique views of the foot
are occasionally helpful to visualize
changes at the tarsometatarsal joint
level Patients with a cavus foot
po-sition often have a degenerative spur
in the posterior aspect of the
subta-lar joint A lateral radiograph of the
patient performing a Coleman block
test will indicate the degree of
cor-rection obtainable with a first ray
os-teotomy A modified Cobey view
may be a better guide for hindfoot
alignment than a calcaneal axial
view.12 A Canale view of the talar
neck is best for finding talar neck
fracture and malalignment.13
Com-puted tomography (CT) scans also
may be of value in assessing
hind-foot position, but they provide only
a simulated weight-bearing view.14A
CT scan of the foot allows more
ac-curate assessment of degenerative
changes within the foot
Techne-tium 99m bone scanning can assist
in identifying involved joints
Anes-thetic blocks of symptomatic joints
can be identified fluoroscopically
and can assist in determining the source of pain
Nonsurgical Treatment Orthoses
An orthotic device may be fash-ioned to broaden the weight-bearing area in the foot Because custom orthoses are expensive and the high-arched foot is hard to fit, patients initially may wish to modify an off-the-shelf insert Commercially available metatarsal pads may be added to a foam rubber insert Pa-tients with first metatarsal head overload may need a cutout for the first metatarsal head Carpet felt also can be added to the shoe, with a cut-out for the first metatarsal head
If the modified shoe insert works,
a custom-made tridensity or
semi-rigid orthosis can be fashioned using the prefabricated insert as a tem-plate A metatarsal pad can be added
to the semirigid or tridensity ortho-sis, with a metatarsal head cutout Hard orthoses are often poorly toler-ated by patients with rigid cavus feet A high-arched orthosis actually may increase ankle instability and may need to be modified A high boot or an off-the-shelf ankle brace may be used Braces that lace up are easier to fit inside a shoe or boot and offer stabilization similar to that of plastic upright ankle braces Patients with muscle weakness often benefit from a full-length cus-tom ankle-foot orthosis (AFO) to prevent foot drop Orthotic modifi-cations can be integrated into the AFO, providing more control over ankle instability than would a brace
Figure 1
The Coleman block test A, On initial examination, the hindfoot is in varus B, The
patient stands with a book or block under the lateral side of the forefoot, and the hindfoot is reexamined Heel varus correction indicates that the hindfoot deformity
is flexible and that the varus position is secondary to the plantarflexed first ray, or valgus position of the forefoot
Trang 5alone Patients with an equinus
de-formity may require a brace to
pre-vent its progression A splint should
be worn every night when the
equi-nus contracture is progressing
Brac-ing also is important for maintainBrac-ing
correction after heel cord
lengthen-ing Often a full clamshell brace or
bivalved cast is required because the
deformity will overcome the
correc-tion obtainable with a posterior
brace and anterior straps
Shoe Wear
The high-arched foot may be
dif-ficult to fit inside a shoe,
particular-ly a slip-on style of shoe Initialparticular-ly, an
off-the-shelf lace-up shoe with an
extra-deep toe box will
accommo-date the foot A lace-up boot has the
added benefit of allowing more room
for the arch and providing some
de-gree of ankle stability Extra depth
and custom shoes may be required
to fit insertable orthoses, AFOs, and
very-high-arched-foot or claw toe
de-formities
Surgical Treatment
Surgical goals, expectations, and
re-covery times should be clearly
out-lined to the patient All normal
joints should be preserved when
pos-sible In patients with muscle imbal-ance, well-planned osteotomies and tendon transfers provide more reli-able outcomes than does triple ar-throdesis Symptomatic degenera-tive joints should be fused and contracted soft tissues released
Contracted tendons also should be released or transferred, or the muscle-tendon junction fractionally lengthened Osteotomies, tendon transfers, or releases can correct muscle imbalance in most patients with a neurogenic cavovarus foot
Although some surgeons recom-mend initial treatment with orthoses and bracing, others believe that, in some cases, surgical inter-vention is indicated as soon as the diagnosis is made A cavovarus clawfoot is a progressive deformity
in the presence of muscle imbalance
Therefore, the muscle imbalance must be corrected to stop the pro-gression before fixed deformity and unsalvageable secondary joint de-generation occur Correction of mus-cle imbalance requires transfer of the two most deforming muscles—
the long peroneal and tibialis poste-rior tendons Consideration should
be given to a lateralizing calcaneal osteotomy and dorsiflexion
osteoto-my of the first ray
Soft-Tissue Release and Tendon Lengthening
In the equinovarus foot, contrac-tures affect the struccontrac-tures of the plantar and medial aspects Depend-ing on the position and extent of the contracture, a posteromedial release will be required A tight heel cord can be addressed with either a gas-trocnemius recession (slide) or heel cord lengthening (Table 2) These procedures are performed for hind-foot equinus deformities, which only are diagnosed by reviewing lat-eral weight-bearing radiographs Forefoot equinus is measured using the talo-first metatarsal angle (nor-mal, 0° to 3°) Hindfoot equinus is measured by a decreasing calcaneal pitch angle as the ankle
plantarflex-es For the patient with a unilateral cavus foot, comparison with a weight-bearing lateral radiograph of the normal side is helpful
When the gastrocnemius compo-nent alone is tight, a gastrocnemius recession can be performed The range of passive ankle dorsiflexion is examined with the knee in both flexion and extension If the range does not change and if the palpated Achilles tendon does not feel tight, then a mechanical block to dorsi-flexion is likely present, caused by a tight posterior capsule, anterior os-teophytes, or a tight soleus compo-nent A weight-bearing lateral radio-graph of the ankle may illustrate impinging anterior osteophytes For open heel cord lengthening, the incision is made just posterior and medial to the ankle joint The Achil-les tendon is identified through this incision by deep dissection The neu-rovascular bundle is identified when
an extensive release is planned.15A percutaneous heel cord lengthening also can be performed, although over-lengthening may result in a calcaneus gait and weakness in plantar flexion
A split tibialis posterior tendon trans-fer should be performed at the same time if the hindfoot is in varus dur-ing the stance phase of gait.16The flexor digitorum longus is lengthened
Soft-Tissue Release and Tendon-Lengthening Procedures
Range of Forced
Ankle Dorsiflexion
(degrees) With the
Knee in Flexion
Range of Forced Ankle Dorsiflexion (degrees) With the Knee Extended Procedure
>10 <5 Gastrocnemius recession
0 to 10 5 (dorsiflexion) to
20 (plantar flexion)
Gastrocnemius recession and/or open heel cord lengthening
<0 20 (plantar flexion) Open heel cord lengthening or
percutaneous Achilles tendon lengthening
<0 Does not change
with knee flexion;
heel cord not tight
Ankle joint débridement and posterior release
<0 Does not change
with knee flexion;
heel cord tight
Percutaneous Achilles tendon lengthening and posterior release if the foot does not correct
Table 2
Trang 6or transferred if the toes are flexed
with the foot in a neutral position
The flexor hallucis longus tendon
may be released at the knot of Henry,
transferred, or fractionally lengthened
at any level at which it can be safely
exposed.17Transfer into a very weak
or paralyzed peroneus brevis can be
very effective
An isolated gastrocnemius
reces-sion is performed using a midcalf
medial incision over the palpable
junction of the gastrocnemius with
the heel cord The tissue plane
be-tween the sural nerve, the fascia, and
the tendon is developed The
isolat-ed gastrocnemius tendon is sec-tioned, and adequate ankle dorsi-flexion with the knee extended is confirmed after the release
Soft-tissue contractures may pre-vent the ankle joint from correcting after tendon release (Fig 2) In this situation, the deltoid ligament can
be released at the posterior aspect of the medial malleolus The ankle and subtalar joint capsule also may need
to be released After isolating the neurovascular bundle, the capsule is identified anterior and posterior to
the tibialis posterior tendon As with
a clubfoot, it may help to divide the posterior aspect of the syndesmosis between the tibia and fibula to allow the talus to rotate posteriorly in the ankle mortise The fat and fascia sur-rounding the superficial and deep compartments also can be scarred or contracted and may need to be re-leased (Fig 2)
The midfoot may be held in the equinovarus position Release of the plantar fascia will allow correction and can be performed by multiple small incisions, excision, or
exten-Figure 2
A,Weight-bearing lateral radiograph of a 44-year-old man with a cavovarus foot deformity associated with severe equinus
secondary to multiple sclerosis B, Weight-bearing lateral radiograph of the normal contralateral foot confirmed that most of the deformity was at the level of the ankle joint, with only a small portion secondary to midfoot cavus C, Weight-bearing lateral
radiograph of the foot in panel A taken 6 months postoperatively A posteromedial release was performed Single-stage
correction was achieved with a cast change under anesthetic at 2 weeks Claw toe deformities were treated by interphalangeal fusions, and residual forefoot valgus deformity was corrected by a dorsiflexion osteotomy of the first ray Calcaneal osteotomy was not required because the foot corrected beyond neutral Eight months postoperatively, the patient ambulated for 1 hour with
a single cane, which was used more for balance than to relieve pain
Trang 7sile release from the calcaneus.18
Midfoot cavus deformities should be
addressed by a plantar fascia release,
with releases of the deep muscles
and their tendon sheaths as
neces-sary.19 An extensive release of the
talonavicular joint capsule also may
be required If the soft-tissue
releas-es fail to correct the foot position,
then osteotomies or fusions will be
required to correct the foot to
neu-tral
After trauma and a compartment
syndrome, correction may require
tendon releases, resection of
infarct-ed tissue within the muscle, and
ad-vancement of muscle tendon units
as well as tendon transfers or
correc-tive osteotomies and fusions.20,21In
Volkmann’s ischemic contracture, a
significant length of the necrotic and
scarred tendon and muscle may need
to be removed to ensure a
perma-nent release This extensive surgical
procedure requires exacting
preoper-ative knowledge of the
neurovascu-lar anatomy of the extremity
Tendon Transfer
Out-of-phase transfers (eg, tibialis posterior to tibialis anterior ten-don transfer) are recommended for younger patients with lower motor neuron pathology The anterior transfer of the flexor digitorum lon-gus and flexor hallucis lonlon-gus ten-dons has been used as an out-of-phase transfer for stroke patients.22
Specific requirements must be met
(1) The transferred muscle should both be strong enough and have an appropriate excursion to perform the function of the substituted mus-cle.18A grade of power will be lost af-ter the transfer (2) The transferred tendon should be inserted close to the substituted tendon and routed in
a comparatively direct line (3) The transferred tendon should be routed
in a tendon sheath, either its own or the sheath of the substituted tendon,
or within tissues that will allow it to glide (4) The nerve and blood supply
of the transferred tendon should not
be damaged (5) The joints on which
the tendon is to act must be func-tional (ie, have a reasonable range of motion, be stable, and have minimal deformity) (6) The tendon should be attached directly to bone, or indi-rectly by another tendon using a ten-don weave, and it should be in slight
to moderate tension For example, the tibialis posterior tendon can be transferred through the interosseous membrane and inserted into the me-dial cuneiform via a weave into the tibialis anterior Agonists are prefer-able to antagonists.18Tendon trans-fers can be categorized according to whether they affect gait in either the swing phase or stance phase5,23,24 (Ta-bles 3 and 4)
Debate exists as to the donor morbidity of the transferred tibialis posterior tendon In the cavus foot position, the released tendon does not cause a subsequent planovalgus deformity because the bones and lig-aments of the foot apparently are able to maintain the medial arch In contrast, the tibialis posterior
ten-In-Phase Tendon Transfers for Swing Phase and Stance Phase
Phase Donor Recipient Indication Concomitant Procedure Swing Extensor
hallucis longus
Tibialis anterior Clawed first ray;
weak dorsiflexion
First ray IP fusion;
MTP joint release Extensor
hallucis longus
Peroneus tertius (complete or split)
Weak dorsiflexion with inversion on swing phase
First ray IP fusion;
MTP joint release Extensor
digitorum brevis
Extensor digitorum longus stump
Clawtoes IP fusions or excisions;
MTP joint releases Extensor
digitorum longus
Peroneus tertius Clawed lesser toes;
weak dorsiflexion
IP fusions or excisions; MTP joint releases Tibialis anterior
(complete or split) Peroneus tertius Excessive forefoot inversionduring swing phase —
Stance Flexor hallucis longus Peroneus brevis Weak ankle eversion Calcaneal osteotomy
Flexor hallucis longus Peroneus longus Flexible forefoot varus Midfoot fusion
Peroneus longus Peroneus brevis Weak ankle eversion Calcaneal osteotomy Peroneus brevis Peroneus longus Weak ankle eversion and
flexible forefoot varus
Calcaneal osteotomy
Tibialis posterior
(complete or split)
Peroneus brevis Weak ankle eversion Calcaneal osteotomy
Tibialis posterior
(complete or split)
Peroneus longus Forefoot varus and
weak ankle eversion
Calcaneal osteotomy
IP = interphalangeal, MTP = metatarsophalangeal
Table 3
Trang 8don is an essential part of the
medi-al column in a flexible planovmedi-algus
foot
For stroke patients, a heel cord
lengthening on its own is rarely
suf-ficient because the tight tibialis
pos-terior tendon will cause a varus heel
position once the foot is
correct-ed.16 Therefore, a tibialis posterior
tendon lengthening or transfer will
be required at the same time
Exces-sive lengthening of the heel cord
should be avoided because increased
cavus deformity or a calcaneus gait
may develop.25 An overlengthened
heel cord also will result in
weak-ness in plantar flexion, poor gait
pro-gression at toe-off, and, in some
cas-es, anterior impingement in the
ankle joint Additionally, increased
energy may be required for gait
be-cause the quadriceps muscle is
re-cruited to prevent the patient from
falling forward Failure to release
tight long toe flexors may result in a
poorer outcome and require a second
release.26 Appropriate releases or
tendon transfers allow the foot to be
brought into the neutral position
and improve or prevent bracing
Walking ability is related to the age
at surgery and the degree of
paraly-sis.22 In patients with hemiplegia,
anterior transfer of the flexor
digi-torum longus and flexor hallucis
longus may assist dorsiflexion
pow-er.27
Osteotomy
The lateralizing calcaneal osteot-omy can effectively reduce the varus moment arm of the Achilles tendon
at the ankle during stance phase;
this osteotomy also can reduce the additive contribution of the Achilles tendon toward the tibialis posterior
in favor of the peroneus brevis dur-ing toe-off The patient with an in-ternally rotated distal tibia also tends to have a varus moment of the Achilles tendon at the ankle The de-gree of tibial rotation can be assessed
by CT.28
An osteotomy is indicated for a mild to moderate fixed deformity that persists after appropriate tendon releases in a patient without
arthrit-ic change in the surrounding joints
Osteotomy also may be indicated in combination with fusion when the foot position cannot be corrected by fusion alone For example, after an ankle fusion, the hindfoot may cor-rect completely, but the forefoot may be left with plantar flexion of the first ray Thus, a dorsiflexion os-teotomy through the first tarsometa-tarsal joint or in the proximal me-taphysis would be indicated
Distal tibial osteotomy may be of value in a patient with forefoot varus, hindfoot varus, and varus alignment at the ankle joint A su-pramalleolar osteotomy with a
later-al closing wedge will bring the foot
flat to the ground and redistribute the force within the ankle joint Supramalleolar derotational os-teotomy also may be beneficial Ro-tating the distal tibia changes the di-rection of the moment arm of the Achilles tendon External rotation osteotomy of the distal tibia in-creases the valgus moment at the subtalar joint and unlocks the subta-lar joint McNicol et al29 reported successful outcomes in patients with polio and other neurologic etiologies who were treated with rotational os-teotomy to externally rotate the foot
In most cases of cavovarus foot, the foot is correctly aligned on the tibia after the talonavicular joint has been released
Calcaneal Osteotomy
When the hindfoot does not pas-sively correct to neutral, a lateraliz-ing calcaneal osteotomy must be performed, with or without a subta-lar fusion Because hindfoot varus is difficult to assess, calcaneal
osteoto-my should be done when there is any residual hindfoot varus The cal-caneal osteotomy will correct the foot during heel strike and at rest and, more important, will lateralize the moment arm of the Achilles ten-don during toe-off In a patient with
a mobile midfoot and hindfoot, a lat-eralizing calcaneal osteotomy in-creases the load on the medial border
Out-of-Phase Tendon Transfers for Swing-Phase Deficit
Donor Recipient Indication Concomitant Procedure Tibialis posterior Tibialis anterior and/or
peroneus tertius
Weak dorsiflexion caused by lower motor neuron pathology, or nerve or muscle injury
Heel cord lengthening
Peroneus longus Peroneus tertius Weak dorsiflexion Tibialis posterior transfer; heel
cord lengthening Flexor hallucis longus
and digitorum
longus
Fourth metatarsal through interosseous membrane
Weak dorsiflexion caused by stroke
Short flexor release;
lengthening of heel cord or tibialis posterior
Flexor digitorum
longus
Extensor hood Intrinsic deformity of toes Interphalangeal joint fusion or
excision
Table 4
Trang 9of the foot during toe-off A
dorsi-flexion osteotomy of the first ray or
a dorsiflexion fusion of the first
tar-sometatarsal joint should be
per-formed at the same time if the first
ray is plantarflexed, as is common in CMT disease
In many patients with a cavo-varus foot requiring a lateralizing calcaneal osteotomy, a posterior and
medial osteophyte is present in the subtalar joint If this is the only ev-idence of degenerative change and is mildly symptomatic, the osteophyte can be excised medially by dissect-ing just anterior to the flexor digi-torum longus
The Dwyer closing wedge osteot-omy weakens the moment arm of the Achilles tendon and often can-not achieve full correction.30A slid-ing calcaneal osteotomy without ex-cision is usually preferable17(Fig 3)
In this procedure, a posterior lateral incision is made The calcaneal cut
is made transverse to the long axis of the foot to prevent shortening or lengthening of the osteotomy The medial cut should not penetrate close to the sustentaculum tali be-cause of the proximity of the neu-rovascular bundle to this groove A skin mark can be made medially halfway between the neurovascular bundle and the tuberosity of the cal-caneus A finger of the surgeon’s nondominant hand is placed on the mark, and the saw is directed to this point After mobilizing both the tu-berosity fragment and the deep investing fascia surrounding the Achilles tendon, lateral translation is performed The osteotomy is held with two screws Anteroposterior, lateral, and calcaneal axial views of the ankle should be taken intraoper-atively The lateral aspect of the tu-berosity fragment is trimmed and can be used for bone graft elsewhere Posterior calcaneal osteotomy with plantar release has been used to correct hindfoot cavus associated with a weak gastrocnemius-soleus complex By sliding the tuberosity of the calcaneus posteriorly and superi-orly using an oblique osteotomy, the position of the calcaneus is
correct-ed and the lever arm of the weak tri-ceps surae muscle is augmented31
(Fig 4) Posterior calcaneal
osteoto-my should not be performed in the presence of anterior ankle joint im-pingement
In this procedure, a lateral inci-sion is made using a portion of the
L-Figure 3
Lateralizing sliding calcaneal osteotomy A, A posterior lateral incision is made.
B,Once the soft tissues have been retracted, the calcaneus is cut with a saw
C, The medial cut should not penetrate close to the sustentaculum tali D and
E,The osteotomy is held with two proximal-distal transcalcaneal screws
F and G, Alternative screw positions (Adapted with permission from Hansen ST Jr
[ed]: Functional Reconstruction of the Foot and Ankle Philadelphia, PA: Lippincott
Williams and Wilkins, 2000, p 369.)
Trang 10or J-shaped calcaneal fracture
inci-sion This incision can be combined
with a sinus tarsi incision if
correc-tion of varus is incomplete after a
subtalar fusion The osteotomy
be-gins anterior to the Achilles tendon
insertion and the insertion of the
plantar fascia An osteotomy
poste-rior to the plantar fascia will
destabi-lize the osteotomy The osteotomy
should be transverse An oblique
os-teotomy lengthens or shortens the
tuberosity of the calcaneus, and
lengthening the calcaneus may
re-strict the correction of varus because
the soft-tissue envelope may become
too tight An oblique osteotomy
ex-iting anteriorly on the medial wall
may damage the neurovascular
bun-dle
The osteotomy site is released
from the medial soft tissues using a
periosteal elevator or curved curet
The Achilles tendon sheath is
re-leased to improve displacement of
the tuberosity fragment; the
invest-ing fascia will prevent translation of
the Achilles tendon The tuberosity
fragment is held by two screws
Af-ter placing the distal screw, the
supe-rior aspect of the postesupe-rior fragment
of the osteotomy is then rotated
me-dially and transfixed with a second
screw Radiographic views (eg,
later-al ankle and Broden views) are
ob-tained to ensure that the screws do
not penetrate the subtalar joint
Lateral Column Shortening
Because lateral column
shorten-ing corrects hindfoot varus, forefoot
varus, and forefoot abduction, it is
ideally suited to correct the position
of a residual clubfoot Lateral
col-umn shortening can be performed
through the cuboid, the lateral
as-pect of the calcaneus, or the
calca-neocuboid joint.18This procedure is
indicated when the foot fails to
cor-rect after medial talonavicular
re-lease
Talar Neck Osteotomy
A malreduced talar neck fracture
can result in dorsal and medial
trans-lation of the distal portion of the ta-lar neck as well as shortening of it
This results in a cavovarus position
of the foot The malunion locks the triple-joint complex, causing a pain-ful rigid foot with overload of the lat-eral border Components of rotation and translation also coexist within the subtalar and midtarsal joints as well as at the malunion, causing overload of the triple-joint complex (subtalar, talonavicular, and calca-neocuboid joints).8
A talar neck osteotomy may be performed when the surrounding joints are well preserved A preoper-ative CT scan is needed to assess the amount of correction required If necessary, intact blood supply to the body is confirmed with magnetic resonance imaging The risks of this procedure include failure to correct all components of the deformity, nonunion of the distraction graft, and osteonecrosis of the talar body.32
Dorsiflexion Osteotomy of the First Ray
Dorsiflexion osteotomy of the first ray is indicated for a symptom-atic plantarflexed first ray with pain
in the forefoot secondary to overload
of the first metatarsal head It is also indicated for a symptomatic plantar-flexed first ray with pain over the lateral border of the foot resulting from supination caused by forefoot-driven hindfoot varus Clawing of the first ray with a dorsal contrac-ture of the metatarsophalangeal joint and a tight extensor tendon are often seen in conjunction Dorsiflex-ion osteotomy or fusDorsiflex-ion of the first tarsometatarsal joint also is
indicat-ed if the hindfoot corrects to neutral when a Coleman block test indicates
a forefoot-driven hindfoot varus
Dorsiflexion fusion of the first tarsometatarsal joint should be con-sidered when the tarsometatarsal joint is hypermobile and a strong peroneus longus plantarflexes the first ray Care should be taken not to over-shorten or over-elevate the first
ray Excessive correction can result
in hallux rigidus and transfer meta-tarsalgia.23 A plantar fascia release may be required at the same time to allow elevation of the first ray The proximal cut of the tar-sometatarsal fusion is almost paral-lel to the joint and is perpendicular
to an imaginary line running through the talus and the navicular
Figure 4
Posterior calcaneal osteotomy for
hindfoot cavus A, Normal relationship
of the hindfoot bones B, Position of the
hindfoot secondary to a weak triceps surae The osteotomy is made from the
lateral aspect C, The posterior
tuberosity fragment is displaced in a dorsal and posterior direction to restore length, reduce the arch, and improve the moment arm of the weak triceps surae muscle The screws are placed in parallel across the osteotomy site (Adapted with permission from
Hansen ST Jr [ed]: Functional Reconstruction of the Foot and Ankle.
Philadelphia, PA: Lippincott Williams and Wilkins, 2000, p 373.)