Amputations II – 2

AMPUTATIONS 2

BELOW-KNEE AMPUTATION

The most proximal level at which near-normal function is available.

INDICATIONS (Haimovici, 1996)
� Gangrene of several toes, extending to or beyond the adjacent metatarsal lesion and showing no tendency to demarcate.
� Spreading gangrene of the foot, with or without associated gangrene of the heel or ankle.
� Spreading gangrene of the toes, associated with uncontrollable infection of the foot.
� Failure of a transmetatarsal or Syme amputation.
� Trauma
� Neoplasia

CONTRAINDICATIONS
� Inadequate circulation for healing!
� Extensive gangrene and infection of the leg with absence of femoral pulses
� Gangrene of the foot associated with irreducible flexion contracture of the knee joint.
� Recent acute occlusion of the femoral or iliac artery with inadequate collateral supply at the below-knee level. (Need a 2-3 month interval for the development of collateral circulation.)
� The nonambulatory patient with a dysvascular limb and flexion contracture of the knee – will be better off with a knee dysarticulation. (McCollough et al., 1981)

TECHNICAL OPTIONS

Long Posterior Myocutaneous Flap
� Most common. Takes advantage of the vascularity of the posterior musculature.
� Moore et al. (1972, Am. J. Surg): superior healing rate (89% vs 72%) after changing from equal AP flaps.

Equal Anterior and Posterior Myocutaneous Flaps
� Still popular in some centres, though falling out of favor.

Equal Medial and Lateral (Sagittal) Myocutaneous Flaps
� Reduces the amount of poorly vascularized anterior skin, utilizes wide-based, short flaps, may provide better bony coverage and wound drainage, and is useful if necrotic skin is present posteriorly.
� Persson, (1974, J. Bone Joint Surg): superior healing rate (74% vs 41%) in 58 pt compared to 40 with equal AP flaps.
� Termansen, (1977, Acta Orthop. Scand): equal healing rate (58% vs 59%) in 41 pt compared to 47 with long posterior flap.

Suffice to say, that in certain situations (trauma in particular), the flap configuration may be dictated by the pattern of tissue loss, so it is important to be aware that there are more than one way to perform the operation.

TECHNICAL OPTIONS (cont�)

Osteomyoplasty
� Requires raising two one-inch osteoperiosteal flaps from the anteromedial and lateral tibia. The tibia and fibula are divided at the level of the osteoperiosteal flap hinge (the fibula 5mm shorter). The flaps are then swung over and attached to the fibula. An osseous bridge then develops between the tibia and fibula, which is believed to stabilize the fibula and improve the end-bearing characteristics of the stump.
� Questionable role in vascular disease – requires the sacrifice of 7.5 cm of stump length, and significantly increased operative time.
� May be indicated in young patients to provide a stronger stump, or in revisions of traumatic supramalleolar amputation. (McCollogough, 1981)

POSTOPERATIVE STUMP MANAGEMENT

Drain vs No Drain?

� A hematoma is a major complication, predisposing to infection which may delay wound healing or sabotage it completely. Revision surgery or more proximal amputation have been known to be caused hematoma formation.
� Kacy et al. (1982, Surg. Gynecol. Obstet.) 113 BKA’s in 100 patients. Wound complications in 55% of drained patients, 16% in those not drained (Penrose drains)
� Tripses and Pollak (1981, Am. J. Surg.) 64 BKA patients. 46% infection rate in drained patients, 20% in undrained.

Conclusion: Meticulous hemostasis is critical. Open drainage is hazardous. Closed drainage may be useful if the patient is oozing a great deal at the conclusion of the case.

Amputations II – 1

AMPUTATIONS 1
AMPUTATIONS

“Amputation is a mutilation attended by not only physical and functional loss but often severe psychological trauma with the body image altered and distorted. Whether by accident or design, the more proximal the loss is, the more there is a progressive reduction in the ability to move, work, and play and even, in some circumstances, to survive. Our first responsibility must be to avoid amputation; all possible alternatives must be explored, evaluated, and rejected only when the evidence points to amputation as the best solution for the patient’s plight.”

G. Murdoch, General Principles of Amputation, in Amputation,
Surgical Practice and Patient Management, 1996

HISTORY

Oldest known artificial limb is a copper and wood leg found in Capri Italy in 1858, supposedly made in 300 BC.

484 BC – Herodotus reports on a Persian soldier, Hegesistratus who escaped from stocks by cutting off his foot and replacing it with a wooden one.

Ambroise Pare, 1529 – the “founder of modern principles of amputation”. Used ligatures to control bleeding, allowing for fashioning of stumps for prosthesis. (survival improved from the old practice of crushing the stump or immersing it in boiling oil to control bleeding).

Morel, 1674 – introduces the tourniquet, making bleeding control much easier. Amputations become more common in Europe for the treatment of open fractures, limbs with vascular injury, and severe joint injury.

James Syme, 1843 – disarticulation of the ankle; developed from his recognition of the fact that Chopart amputations (midtarsal disarticulations) were less likely to get “hospital disease” (infection).

Lister, 1867 – antiseptic technique; a true milestone in amputation surgery.

Civil War

World War I Throughout history, war remains the most significant
impetus to the advancement of amputation surgery.
World War II

Radcliffe and Foort, 1961 – developed the rationale and techniques of fabrication for the patellar-tendon-bearing prosthesis

Weiss, 1963 – myoplasty technique revisited.

International Society for Prosthetics and Orthotics – Denmark, 1970
GENERAL PRINCIPLES

In general, there are two goals of amputation surgery:
1. Ablation: Remove all that is necessary to eliminate the pathologic
state and provide primary or secondary wound healing.
2. Reconstruction: Create the optimum motor and sensory end-organ
for prosthetic substitution and restoration of function.

LEVEL
� The most distal level of amputation consistent with the disease state and a well-healed, non-tender, physiological residual limb – ie. a balance between limb length and wound healing.

SKIN
� Gentle handling and eventual tension-less (but not redundant) closure is critical.
� Broad-based skin flaps with minimal elevation to avoid compromising blood supply.
� Split and full-thickness skin grafts are permissible with modern prosthetic fitting and technology – resistance to shear and pressure is comparable to normal skin over time

MUSCLE
� Functioning muscle provides the limb with strength, size, shape, circulation, metabolic exchange, and proprioception.
� Distal muscle stabilization allows resistance to contraction; lessens weakness and atrophy
� When anatomical circumstances permit, distal attachment of tendons and aponeuroses to the periosteum and/or bone (myodesis) should be performed, ideally under physiological tension.

NERVE
� Neuroma formation is inevitable.
� The nerve should be gently pulled down, ligated, divided cleanly, and allowed to retract proximally into healthy muscle. (Dellon et al., 1984). This allows the neuroma to lie well away from incision scar, cushioned by muscle from traction or pressure from the prosthesis wall. Excess traction when cutting should be avoided.

BONE
� Sectioning of bone should be at a length consistent with soft-tissue coverage and closure.
� Bone edges must be smoothly contoured.
� Power saws cause thermal necrosis and should be cooled with saline.
� If possible, close periosteum over the end of cut diaphysis; otherwise, resect it circumferentially. WOUND CLOSURE
� Physiologic tension is ideal.
� Avoid running sutures. Some authors close only the skin with a combination of interrupted sutures and steri-stips.
� Closed suction drainage, if necessary, is preferable to Penrose drains (infection).

Amputations I – 5

Amputations 5
Hip Disarticulation Few hip disarticulation amputees will become
functional walkers due to the high energy cost of prosthetic ambulation.
Posttrauma or tumor patients will occasionally use a prosthesis for limited
activity. These patients sit in their prostheses and must use their torsos
to achieve momentum to throw the limb forward and advance the limb.

Prosthetic fitting for growing children is challenging because
frequent adjustments are needed. Prosthetic fitting should be initiated to
closely coincide with normal skill development. In the upper limb, this
development begins at the time of sitting balance, usually 4 to 6 months of
age. Initially, a passive rubberized terminal device with blunt rounded
edges is used. Active cable control and a voluntary opening terminal device
are added when the child exhibits initiative in placing objects in the
terminal device, usually in the second or third year of life. Myoelectric
prostheses are not usually prescribed until the child has mastered
body-powered componentry.

In the lower limb, prosthetic fitting usually coincides with crawling
and pulling to stand at 8 to 12 months of age. Knee control at the
transfemoral level cannot be expected until the child demonstrates
proficiency in walking with a locked knee. Children will have unusual gait
patterns, and formal gait training should be delayed until age 5 to 6
years.

Amputations I – 4

Amputations 4
Hindfoot Amputation Whereas some authors have reported reasonable
functional outcomes with hindfoot amputation, ie, Chopart’s or Boyd’s,
especially in children, the functional outcome is generally poor at these
levels. Most patients with hindfoot amputation retain an inadequate lever
arm, and are prone to develop significant equinus. In addition, they lack
push-off at terminal stance.

Ankle Disarticulation (Through-Ankle, Syme’s) This is a durable
amputation level that allows direct load transfer and is rarely complicated
by late residual limb ulcers or tissue breakdown in young traumatic
amputees. It provides a stable gait pattern that rarely requires
postoperative gait training. Previously, it had been suggested that a
Syme’s amputation be done in two stages. However, recent data suggest that
it can be performed in one stage, even in ischemic limbs with insensate
heel pads. The malleoli and metaphyseal flares should be removed from the
tibia and fibula, but the remaining tibial articular surface should be
retained to provide a resilient residual limb. The heel pad should be
secured to the tibia via drill holes, either anteriorly or posteriorly.

Transtibial (Below-Knee) The long posterior myocutaneous flap is
preferred to sagittal flaps in transtibial amputation. Optimal bone length
is 12 to 15 cm below the knee joint, or longer if adequate gastrocnemius or
soleus can be used to construct a functional soft-tissue envelope
comprising a mobile muscle mass and full-thickness skin. Posterior muscle
should be secured to the beveled anterior tibia by myoplasty or myodesis.
Rigid dressings should be used during the early postoperative period, and
weightbearing should be initiated between 5 and 21 days following surgery
if the residual limb is capable of transferring load. Young active
transtibial amputees have the greatest benefit from the new technology,
including flexible sockets, silicone liner suction, suspension, and dynamic
response feet.

Knee Disarticulation (Through-Knee) Knee disarticulation is
performed using sagittal skin flaps and covering the end of the femur with
gastrocnemius to act as a soft-tissue envelope end pad. This level is
generally performed in the nonambulator who can support wound healing at
the transtibial, or distal level. This level is muscle-balanced, and it
provides an excellent weightbearing platform and lever arm for transfer.
When performed in a potential walker, it provides a direct load transfer
residual limb that can take advantage of the intrinsically stable
polycentric four-bar linkage prosthetic knee joint.

Transfemoral (Above-Knee) This level provides significant problems
in energy cost for walking. Transfemoral amputees who have peripheral
vascular disease are unlikely to be prosthetic ambulators. Salvaging the
limb at the knee disarticulation, or transtibial level is essential to
allow potential prosthetic ambulation in geriatric, dysvascular amputees.
The optimal transfemoral bone length is 12 cm above the knee joint to
accommodate the prosthetic knee. Adductor myodesis maintains normal femoral
adduction during stance phase, allowing optimum prosthetic function.

Ischial containment sockets improve comfort and suspension, but waist
belts of various types are frequently necessary. Although suction
suspension remains the primary mode of suspension, silicone liners, much
like those used in transtibial amputation, may be used.

Amputations I – 3

Amputations 3
Krukenberg’s Amputation This kineplastic operation transforms the
transradial residual limb into radial and ulnar pincers capable of strong
prehension and excellent manipulative ability due to the retention of
sensation. Due to psychologic considerations, it is generally restricted to
blind bilateral amputees who cannot use visual cues to operate their
prostheses (Fig. 2).

Elbow Disarticulation/Transhumeral Amputation Functionally, both
levels require two acts to develop prehension, making these amputations
significantly less functional and making the prosthesis heavier than the
prosthesis for amputation at the transradial level. The length and shape of
elbow disarticulation provides improved suspension and lever arm capacity
compared to the transhumeral amputation. The drawback is cosmetic, because
the elbow will be too far distal and the forearm shank too short for the
limbs to be of equal length. Prosthetically, the best function with the
least weight at the lowest cost is provided by hybrid prosthetic systems
combining myoelectric, traditional body-powered, and body-driven switch
componentry for elbow disarticulation or transhumeral amputation.

Patients with a complete unreconstructable brachial plexus injury can
achieve function by amputation of the insensate dead-weight arm, leaving a
sensate residual limb which can be fitted with a prosthesis. If no
voluntary shoulder motion remains, shoulder fusion allows scapulothoracic
motion to drive the prosthesis.

Shoulder Disarticulation/Forequarter Amputation These levels of
amputation provide minimal function, because the patient must sequentially
control two joints and a terminal device. Limited function can be achieved
with a manual universal shoulder joint positioned by the opposite hand,
combined with a lightweight hybrid prosthetic components.

Lower Limb

Two major recent advances in lower limb prosthetics are socket design
and fabrication, and dynamic-response feet. New plastics allow sockets to
be lighter and more flexible, and therefore, more comfortable.
Computer-assisted design and fabrication allow more efficient fabrication
with the newer materials. The standard quadrilateral prosthetic socket for
transfemoral amputees is gradually being replaced by the newer ischial
containment socket designs, which more efficiently transfer load by total
contact. Silicone sleeves, used primarily in transtibial levels, improve
comfort and suspension. Dynamic response feet now provide spring and
push-off to the amputee’s gait, probably lessening the energy demands for
walking or running.

Toes The great toe, primarily, and the lesser toes act as
stabilizers during stance phase. Ischemic patients generally ambulate with
an apropulsive gait pattern, so they suffer little disability from toe
amputation. Traumatic amputees will lose some late stance-phase stability
with toe amputation. When amputation of the great toe is necessary, an
attempt should be made to salvage the proximal aspect of the proximal
phalanx with the insertion of the flexor hallucis brevis in order to
maintain some stabilizing function. Isolated second toe amputation should
be amputated just distal to the proximal phalanx metaphyseal flare to act
as a buttress that prevents late hallux valgus.

Ray Resection Single outer (first or fifth) ray resection functions
well in standard shoes. Resection of more than one ray leaves a narrow
forefoot that is difficult to fit in shoes. Central ray resections are
complicated by prolonged wound healing, and rarely outperform midfoot
amputation.

Midfoot Amputation There is little functional difference between
transmetatarsal and tarsal-metatarsal (Lisfranc) amputation. The long
plantar flap used in these amputations acts as a myocutaneous flap and is
preferred to fish-mouth dorsal-plantar flaps. Transmetatarsal amputation
should be performed in the distal shaft to retain lever arm length, or
through the proximal metaphyses to prevent late plantar pressure ulcers
under the residual bone ends. A percutaneous Achilles tendon lengthening
should be performed with the Lisfranc amputation to balance the foot to
prevent the late development of equinus or equinovarus. Late dynamic varus
occurring during stance phase of gait can be corrected with lateral
transfer of the tibialis anterior tendon. Midfoot amputees rarely require
the stability of high-topped shoes, generally being sufficiently stable
with standard tie shoes.

Amputations I – 2

Amputations 2
AMPUTATION LEVELS AND PROSTHETIC PRINCIPLES

Upper Limb

The shoulder provides the center of the radius of the functional
sphere of the upper limb. The elbow acts as the caliper to position the
hand at a workable distance from that center to perform tasks. People
normally perform multiple joint segment tasks simultaneously. Upper limb
prostheses perform these same tasks sequentially; thus, limb length and
joint salvage are directly correlated with functional outcome. Motion at
the retained joints is essential to maximize that function. Residual limb
length is valuable for both prosthetic socket suspension and providing the
lever arm necessary to drive the prosthesis through space.

Limb salvage is more critical in the upper limb than the lower limb,
because sensation is critical to upper extremity function. An insensate
prosthesis provides less function than a partially sensate, partially
functional salvaged limb. This fact is in contradistinction to the retained
lower limb in which function is not as dependent on sensation.

When upper limb amputation is necessary, prosthetic fitting should be
initiated as soon as possible, even before the wound is healed. Outcomes of
prosthetic limb usage vary from 70% to 85% when prosthetic fitting is
initiated within 30 days of amputation, as opposed to less than 50% when
prosthetic fitting occurs late.

Myoelectric prostheses are promising, but are slow to perform tasks.
Increased speed and power requires increased weight for the motor and
battery pack. These prostheses appear to be most successful in the
midlength transradial amputee, in whom only the terminal device needs to be
controlled.

Hand Amputation Surgical reconstruction to obtain prehension can be
accomplished with pollicization, ray transposition, central ray resection,
or toe-to-hand transfer. Functional static partial hand prostheses can
provide a stable post for opposition from remaining digits or the palm.
Cosmetic partial hand prostheses may be psychologically beneficial because
they retain body image.

Wrist Disarticulation Wrist disarticulation has two advantages over
transradial amputation: (1) preservation of more forearm rotation due to
preservation of the distal radioulnar joint, and (2) improved prosthetic
suspension due to the flare of the distal radius. However, wrist
disarticulation provides challenges to the prosthetist that may outweigh
its benefits. Cosmetically, the prosthetic limb will be longer than the
contralateral remaining limb, and, if myoelectric componentry is used, the
motor and battery cannot be hidden within the prosthetic shank.

Transradial Amputation High levels of function can be obtained at
this level of amputation (Fig. 1). Forearm rotation and strength are
directly related to the length of the residual limb, with the optimum
length being at the junction of the middle and distal thirds of the
forearm. At this level, the soft-tissue envelope can be constructed with
adequate muscle myoplasty or myodesis, and the components of a myoelectric
prosthesis can be hidden within the prosthetic shank. Because function at
this level is accomplished prosthetically only by opening and closing the
terminal device, elbow joint function is essential. When the residual
forearm is so short as to preclude an adequate lever arm for driving the
prosthesis through space, supracondylar suspension (the Munster socket) and
step-up hinges can be used to augment function.

Amputations I – 1

Amputations 1
Amputations

COMPLICATIONS

Pain

Phantom limb sensation, the feeling that all or part of an amputated
limb is present, occurs in virtually all adults following an amputation. It
usually diminishes with time. Phantom pain is a burning, painful sensation
in the distribution of the amputated part. It is present in less than 10%
of adults with acquired amputations. Noninvasive treatments, such as
increased prosthetic limb use, physical therapy modalities, intermittent
compression, and transcutaneous electrical nerve stimulation, often will
decrease symptoms.

A more common cause of residual limb pain is a condition that is
similar to reflex sympathetic dystrophy. In this condition, the pain is
within the residual limb. The pain is described as burning, tearing,
throbbing, or piercing. These patients frequently underwent amputation
following a crush injury and, therefore, have symptoms much like those of a
major causalgia. The personality traits of these patients often mirror
those of the reflex sympathetic dystrophy population.

Localized residual limb pain is often related to an incompetent
soft-tissue envelope, prominent underlying bony projection, or scarred deep
structures. An etiology of pain not directly related to the amputation
should be considered. Ischemia of the residual limb is an occasional
etiology of pain in the patient with peripheral vascular disease. Nerve
entrapment, disk herniation, proximal arthritis, or visceral etiologies
occasionally cause pain in the residual limb.

Edema

Postoperative residual limb edema is common following amputation. It
is uncomfortable for the patient, and it may impede wound healing by
increasing tissue and venous pressures. Rigid dressings help reduce this
problem. If soft dressings are used, they should be combined with
compression stump wrapping. Compression stump wrappings, if too tight
proximally, can produce bulbous distal swelling and a residual limb that is
difficult to encase within a prosthetic socket. Compression wraps in
transfemoral residual limbs fall off if not suspended about the waist.

Late residual limb swelling can be produced by proximal constriction
of the prosthetic socket, thus causing congestion in the stump. In its most
severe form, verrucous hyperplasia develops in transtibial amputations when
distal total contact is not achieved. This condition is characterized by a
wart-like overgrowth of skin combined with darkened pigmentation,
fissuring, and a serous discharge, which often becomes secondarily
infected. The cellulitis is treated with broad spectrum antibiotics and
avoidance of socket wear. The prosthetic socket needs to be altered on an
ongoing basis to provide total contact, until a volume stable residual limb
with a healthy soft-tissue envelope is achieved.

Joint Contractures

Joint contractures usually occur between amputation surgery and
prosthetic fitting. They are best avoided by early prosthetic fitting and
weightbearing, combined with an aggressive physical therapy program. Hip
flexion contractures in transfemoral amputation can be produced at the time
of surgery by performing myodesis or myoplasty with the retained muscles
tensioned with the hip in a flexed position.

Preoperative, static joint contractures need to be corrected at the
time of surgery, because they rarely can be corrected postoperatively. The
transfemoral amputee should be encouraged to lie prone after surgery to
prevent hip flexion contracture. The transtibial amputee should not sit for
long periods with the residual tibia unsupported in a flexed knee position.

Wound Failure

Wound failure following amputation is not uncommon, especially in
diabetic and ischemic limbs. Open wound care can be used for small wounds.
Even larger wounds can be managed with total contact plaster or plastic
sockets and continued weightbearing, as long as the bone is not exposed.
When localized wound failure is larger, or the bone is exposed, or the
soft-tissue envelope is tight (as long as the vascular inflow remains
adequate), the residual limb can be revised by shortening the bone,
resection of a wedge of soft tissue, and nontensioned wound closure.

Dermatologic Problems

Many skin problems can be prevented by good hygiene, which includes
keeping both the residual limb and socket clean, dry, and free of any
residual soap. Epidermoid cysts can occur at the socket brim. They are best
managed by modification of the socket to relieve localized pressure.
Contact dermatitis can be confused with infection. It is often caused by
retained detergents or soaps. Treatment involves good hygiene practices and
topical steroid creams. Folliculitis or acneform hidradenitis is common.
Meticulous hygiene, sweat-absorbing stump socks made from natural fibers,
and occasional courses of oral tetracycline therapy can usually control
this problem.

Amputation Versus Limb Salvage

Amputation versus Limb Salvage

Reference: Tornetta Paul, Olson Steve, Instructional Course Lectures, 1997, Chapter 50

Main Message

It is difficult to calculate the different factors that contribute to limb salvage-ability in a meaningful way in order to predict who needs an amputation and who should have limb salvage.

Points of Interest

Consider amputation for severe IIIB and IIIC open injuries.
Factors that affect salvage include: vascular injury, degree of soft-tissue damage (influenced by the type of trauma – blunt vs penetrating), and others – age, injury score, comorbidities, other injuries

Scoring systems
Mangled extremity severity index – MESI
Mangled extremity severity score – MESS
Predictive salvage index – PSI
Limb salvage index – LSI
Nerve injury, ischemia, soft-tissue contamination, skeletal, shock, age – NISSA

Things that are considered in these scores:

ISS
Nature of skin injury
Vascular injury
Bony injury
Age
Pre-existing disease
Time to OR
Venous injury

None have been all that good at predicting outcome. The scoring systems are all affected by the subjective nature of the determination of the degree of soft-tissue injury, as well as the extent of ischemia and the severity of the venous injury.

Bonnani – Journal of Trauma, 1993: evaluated MESI, MESS, PSI, LSI and found that none were very successful in predicting the outcomes. Entitled “The Futility of Predictive Scoring of Mangled Lower Extremities”

Thoughts….

Just remember, they may be better off with amputation immediately.

Fractures And Dislocations Of The Foot 2

Fractures and dislocations of the foot 2
base of the second metatarsal. Note that there lacks such strong reinforcement between the first and second metatarsal bases, making this an area of instability.
– the key radiographic landmarks are: congruity from the medial border of the 2nd metatarsal and the medial border of the middle cuneiform; and congruity from the medial border of the 4th metatarsal and the medial border of the cuboid.

Classification (Quenu, Kuss)
Homolateral – all five metatarsals going in one direction
Isolated – one or two metatarsals
Divergent – usually between the first and second metatarsals

– needs careful clinical examination: these dislocations may reduce and look okay on xray, so you may overlook the severity of the injury
– look for pain on passive supination/pronation of the foot.
– on xray, fractures of the navicular, cuboid, cuneiforms, or of the metatarsal bases (particularly the second metatarsal) should make your suspicion increase.

Treatment
– some authors have recommended cast treatment if the joint is reduced. Others suggest that the reduction can be lost when the swelling subsides and recommend fixing them
– it would appear that the most reliable way to treat these is to fix them; certainly, any displacement warrants reduction and stabilization
– Myerson’s guidelines – ORIF if >2mm displacement or a talometatarsal angle of > 15o.
– ORIF can be done through a dorsal longitudinal incision over the 1st/2nd interspace – this gives access to the 2nd metatarsal head which is usually the tough one to get reduced. Be aware that an entrapped anterior tibial tendon can block the reduction of the 2nd metatarsal.
– Fixation either with stout K-wires (0.062) or interfrag screw

Fractures And Dislocations Of The Foot – Midfoot Injuries

Fractures and Dislocations of the Foot – Midfoot Injuries

Reference: Heckmann, James, in Rockwood and Green, 1996, Chapter 32

Main Message

These are often overlooked injuries that require a keen index of suspicion.

Points of Interest

Chopart’s Joint

Biomechanically designed to allow for flexibility of the midfoot on heelstrike, then rigidity on toe-off; when the subtalar joint is everted (on heelstrike) the talonavicular and calcaneocuboid joints are parallel, allowing some motion at the midtarsal joint. When the foot rolls into toe-off, the subtalar joint inverts and the talonavicular and calcaneocuboid joints diverge, locking the midtarsal joint and creating a rigid lever upon which to push off.fs

5 mechanisms of injury (Main and Jowett, JBJS 57B, 1975)
– Medial stress injury (most common) – severe inversion of the foot
– Longitudinal stress injury – severe force applied longitudinally from distal to proximal to the metatarsal heads with the foot plantarflexed – pushes up the rays into the navicular and cuneiform, which fracture. The navicular tends to fracture in line with the cuneiforms.
– Lateral stress injury – eversion injury, with a crush to the cuboid or anterior calcaneus as the forefoot is driven laterally (nutcracker fracture of the cuboid), with possible avulsion off the navicular.
– Plantar stress injury – plantarly directed force pushes the navicular and cuboid down, often avulsing the dorsal lip.
– Crush injury – for all those other unclassified injuries.

Treatment

– needs diagnosis first! These are often missed!
– if undisplaced – cast x 6 weeks
– if displaced, frequently need ORIF with K-wires or screw fixation.
– arthrodesis down the road for residual disability; some favor primary arthrodesis, but most would recommend trying to fix as best as possible first.

Navicular Fractures

– Cortical Avulsion
– Tuberosity
– Body

Cortical Avulsion
– avulsion of the talonavicular capsule and anterior fibers of teh deltoid ligament with eversion
– treat with splinting, then walking cast 4-6 weeks; If large, fix them to restore congruity of the talonavicular joint.

Tuberosity Fragment
– avulsion of the tib post tendon by acute eversion of the foot.
– make sure it is not an accessory navicular
– treat nondisplaced with walking cast, 4-6 weeks. If significant proximal displacement occurs, fix them immediately to restore length of the tib post tendon. If nonunion and pain persist, then excise them.

Body Fractures
– can be in the coronal plane, or in a sagital plane with displacement of the foot in a medial or lateral direction
– undisplaced fractures get casting, the rest should be reduced and fixed.
– the key is to recognize the whole injury to the foot, of which the navicular fracture may be just one manifestation of (ie – midtarsal dislocation, Lisfranc injury, etc..)

Stress Fracture
– look out in large, heavy basketball players
– treat with non-weightbearing cast for 6-8 weeks; may take 6 months to heal!

Cuboid Injuries
– most commonly, a “nutcracker” fracture from being forced between the anterior process of the calcaneus and the 5th metatarsal.
– when undisplaced, short leg walking cast x 6 weeks
– if severe shortening of the lateral column, may need to bone graft, +/- arthrodesis of the calcaneocuboid joint.

* when looking at fractures in the navicular, cuboid, or cuneiforms, look at the foot as a whole – how did the fracture occur? What were the forces? Is there a more extensive ligamentous injury from a subluxation or dislocation of the midtarsal or Lisfranc joint?

Lisfranc Injuries (Tarsometatarsal)

– intrinsic stability is provided primarily by the bony architecture – the second metatarsal locks into the space between the medial and lateral cuneiforms.
– transverse metatarsal ligaments holds the heads together, and the 4 lateral bases are similarly held together; “Lisfranc’s ligament” is an especially strong structure extending from the medial cuneiform to the