Phẫu thuật đầu gối docx

Finally, val-gus alignment may represent a post-traumatic deformity and be the result of a tibial malunion, physeal arrest, or tibial plateau fracture.14 Despite the well-known associati

Most surgeons agree that the

ar-thritic knee with valgus deformity

presents a unique set of problems

that must be addressed at the time

of total knee arthroplasty (TKA)

Correction of the deformity and

restoration of anatomic alignment

should be achieved to maximize the

longevity of the replaced

compo-nents Although several authors

have suggested TKA as a potential

treatment for the knee with severe

valgus deformity,1-9 none has

com-prehensively reviewed the extensive

kinematic and anatomic variables

that need to be understood in

at-tempting to balance the TKA in a

patient with a valgus deformity

The valgus knee may have any

combination of primary or

sec-ondary bone and soft-tissue

abnor-malities These include contracted

lateral capsular and ligamentous

structures, lax medial structures,

and acquired or preexisting bony

anatomic deficiencies This

constel-lation of pathology makes attaining

soft-tissue balance when the knee is

returned to physiologic alignment

extremely difficult The recent liter-ature10,11has underscored the im-portance of ligament balancing and

of assessing this balance throughout

a range of motion during the trial reduction of the total knee compo-nents In the 1970s, Freeman et al12

and Insall13were among the first to emphasize this basic principle with the introduction of a tensor instru-ment and laminar spreader to assess the symmetry of the flexion and extension gaps The development and more frequent use of both con-strained posterior stabilizing/poste-rior cruciate substituting prostheses and total stabilizing prostheses, as well as the introduction of “mea-sured resection” instrumentation, might suggest that less attention can

be paid to this basic principle of bal-ancing the knee However, if

prop-er ligament balancing techniques are used and proper ligament bal-ance is attained, the knee may not require the use of a more con-strained component

A thorough understanding of the pathologic anatomy and a

meticulous preoperative evaluation

to demonstrate fully the individual patient’s anatomic deficiencies are critical to effective surgical man-agement

Etiology

Valgus deformity in adults com-monly is associated with inflamma-tory arthritis as well as with primary osteoarthritis, posttraumatic arthritis,

or even overcorrection from a high tibial osteotomy for a preexisting varus deformity Likely a significant percentage of adult patients with lat-eral compartment osteoarthritis and associated valgus deformity repre-sent unresolved physiologic valgus deformity Occasionally, persis-tence of genu valgum from child-hood may exist secondary to meta-bolic disorders, such as rickets and

Dr Favorito is Orthopaedic Surgeon, Welling-ton Orthopaedics and Sports Medicine, Cincinnati, Oh Dr Mihalko is Associate Pro-fessor, Department of Orthopaedic Surgery, State University of New York at Buffalo, Buffalo, NY Dr Krackow is Chief of Ortho-paedics, Kaleida Health System, The Buffalo General Hospital, and Professor of Orthopae-dics, State University of New York at Buffalo, Buffalo.

Reprint requests: Dr Krackow, The Buffalo General Hospital, 100 High Street, Suite B2, Buffalo, NY 14203.

Copyright 2002 by the American Academy of Orthopaedic Surgeons.

Abstract

The valgus knee presents a unique set of problems that must be addressed

dur-ing total knee arthroplasty Both bone and soft-tissue deformities complicate

restoration of proper alignment, positioning of components, and attainment of

joint stability The variables that may need to be addressed include lateral

femoral condyle or tibial plateau deficiencies secondary to developmental

abnor-malities, and/or wear; primary or acquired contracture of the lateral capsular

and ligamentous structures; and, occasionally, laxity of the medial collateral

ligament Understanding the specific pathologic anatomy associated with the

valgus knee is a prerequisite to selecting the proper surgical method to optimize

component position and restore soft-tissue balance.

J Am Acad Orthop Surg 2002;10:16-24

Paul J Favorito, MD, William M Mihalko, MD, PhD, and Kenneth A Krackow, MD

renal osteodystrophy Finally,

val-gus alignment may represent a

post-traumatic deformity and be the

result of a tibial malunion, physeal

arrest, or tibial plateau fracture.14

Despite the well-known associations

of valgus deformity of the knee with

rheumatoid arthritis, rickets, and

renal osteodystrophy, these patients

make up a small proportion of those

requiring TKA In four of the five

clinical series that utilized TKA in

patients with valgus deformity of

the knee, primary osteoarthritis was

overwhelmingly the most common

etiology, with a smaller number of

patients having rheumatoid arthritis

and posttraumatic arthritis.5-9 Even

less common etiologies included

other inflammatory disorders and

osteonecrosis

Alignment

The normal mechanical axis of the

knee is defined as a line that passes

from the center of the hip to the

cen-ter of the ankle (Fig 1, A) Normal

alignment is defined by the fact that

the line passes through the center of

the knee In the knee with valgus

deformity, the center of the joint lies

medial to the mechanical axis (Fig

1, B) The anatomic axes of the

femur and tibia are represented by

lines down the center of their

re-spective shafts The anatomic

fem-oral axis is commonly 5 to 6 degrees

lateral to or “offset” from the

fem-oral mechanical axis, while the

mechanical and tibial shaft axes are

coincident The 5- to 6-degree

ana-tomic axis of the femur may be

decreased by the pressures of coxa

valgum or in patients who have

undergone total hip arthroplasties

When normal knee alignment

exists, the angle between the

me-chanical axes of the femur and the

tibia is zero The radiographic

de-formity can be defined as the angle

drawn between the mechanical axis

of the femur (i.e., the middle of the

femoral head to the middle of the femoral surface of the knee, not of the entire lower extremity) and the shaft axis of the tibia Alterna-tively, one can define deformity using the tibiofemoral angle, or the angle created between the anatomic axes of the femur and tibia It is therefore very important to pro-vide the specifics of the orientation measurement system to avoid con-fusion In this article, we use the term “tibiofemoral angle” to de-scribe the “anatomic tibiofemoral angle” to emphasize that we are considering the position of the ana-tomic shaft axes

Although various measurements have been reported,1-9a valgus knee generally is defined as a tibio-femoral angle >10 degrees Clearly,

a tibiofemoral angle of 7 to 9 de-grees is larger than normal, but patients with smaller deformities have typically not been included in study cohorts evaluating treatment

of valgus knees

The definition of the deformity based solely on the position of bony landmarks on radiographs does not provide complete information re-garding the nature of the deformity, especially of the involvement of periarticular soft tissues A major component of the surgeon’s task in managing deformity is the direct result of the coexisting asymmetry and/or contractures of the soft tis-sues, not just the abnormalities of bony alignment relative to the initial weight-bearing radiograph For ex-ample, in a patient with acute frac-ture and collapse of the lateral tibial plateau (assuming no preexisting deformity and no secondary con-tracture of soft tissues since frac-ture), placement of a distracting device into the knee joint will “jack”

open the lateral compartment so that a space defect is apparent, while the overall alignment of the tibia and femur is normal This emphasizes the importance of assessing deformity in terms of the

“asymmetry” of the soft-tissue sleeve To assess that asymmetry intraoperatively, a tensor instru-ment as originally introduced by Freeman et al12 or spacer blocks as described by Insall13may be used

Intraoperative Considerations Incision and Exposure

A median parapatellar approach is most commonly used during sur-gery even though most of the pathology is on the lateral side of the valgus-deformed line Patellar eversion is relatively easy because

of the combination of the valgus deformity and the relative lateral-ization of the tibial tubercle The

Figure 1 A, The mechanical axis of the

knee without deformity B, The

mechani-cal axis of the knee with valgus deformity.

knee is then gently flexed and the

joint can be exposed Although most

of the required soft-tissue releases

are of the lateral structures and

rather distant from the anteromedial

arthrotomy, the valgus deformity

sufficiently facilitates general

expo-sure so that access to the

posterolat-eral corner of the knee joint is not

difficult, even in patients with

ex-treme obesity

Keblish15has developed and

re-ported on the use of a lateral

reti-nacular approach for the valgus

knee The potential advantage of

this exposure is the direct access to

the lateral retinacular and capsular

ligamentous tissues for release In

addition, there is no disruption of

the medial blood supply to the

pa-tella, thus presumably lessening

the chances of patellar

devascular-ization from sacrifice of the lateral

geniculate vessels during

aggres-sive lateral retinacular release

This lateral exposure has gained

some proponents but has not

achieved universal acceptance

There are two main considerations

with this approach The first is that

the normal position of the tibial

tubercle is lateral to the midline,

and this position is accentuated by

valgus deformity A lateral

para-patellar exposure therefore does not

offer as wide a view of the central

and medial aspects of the knee To

overcome this, it is typically

neces-sary to perform a modified “wafer”

osteotomy of the tibial tubercle,

which must carry the inherent risks

of postoperative patellar tendon

failure and nonunion

The second issue relates to

suffi-cient tissue for wound closure

After the lateral side of the knee

has had the appropriate releases to

achieve balance, there may be only

skin and subcutaneous tissue

avail-able for closure Techniques have

been developed to address this

problem; these include a Z-cut

cap-sulotomy or advancing the fat pad

over the anterolateral joint line to

provide closure elements Neverthe-less, these two potential causes of morbidity must be weighed against the more direct access to the con-tracted tissues

Bony Architecture

Lateral bone deficiency is a common component of the valgus knee de-formity and may involve both the lateral femoral condyle and/or the posterior aspect of the lateral tibial plateau (Fig 2) Proper femoral component placement for TKA is achieved by referencing the cutting jig system on the posterior femoral condyles or epicondylar axis How-ever, the epicondylar axis may be difficult to determine intraopera-tively.16 Therefore, if the lateral femoral condyle is deficient and the posterior femoral condylar axis is used, an inappropriately large amount of bone will be resected from the posterior aspect of the lat-eral condyle Improper resection may result in internal rotation of the femoral component and obligate medial placement of the patellar groove Malpositioning of the femoral condyles has the effect of internally rotating the entire extrem-ity Furthermore, the relationship with the contracted lateral liga-ments creates an abnormal patello-femoral alignment The end result

is an increased Q-angle and abnor-mal patellar tracking

Alternatively, proper femoral component rotation may be best achieved by using the anteropos-terior (AP) axis, as described by Arima et al.16 The AP axis is de-fined by a line parallel to and bi-secting the intercondylar notch (a line through the deepest part of the patellar groove anteriorly and the center of the intercondylar notch posteriorly) (Fig 2, B) This line is also approximately perpendicular to the epicondylar axis In a study by Whiteside and Arima17 reviewing

107 patients in whom the AP axis was used for TKA in the valgus

knee, only one patient required a tibial tubercle transfer for patellar malalignment

Gap Kinematics

The relationship of the proximal tibia to the distal femur, as repre-sented by the gap created by bone deficiency, and how it changes while performing ligament balanc-ing, may be referred to as gap kine-matics Proper balancing of the joint gaps must be achieved so that once the gaps are filled with suit-ably articulating knee components, the static tension of the surrounding soft-tissue sleeve will allow for a stable construct If asymmetry and inequality exist in the soft-tissue sleeve, properly articulating compo-nents may have no primary support

to keep them stable under antago-nistic dynamic forces (Fig 3) There-fore, it is mandatory to create an essentially stable joint gap through-out the entire range of flexion and extension

The valgus knee is approached by first determining if the deformity is passively correctable during the ini-tial clinical examination under anes-thesia, and then again intraopera-tively once all osteophytes have been removed If, after the preliminary bone cuts have been performed, the deformity is corrected and the joint

Figure 2 Bony and rotational deformity of

the distal femur of the valgus knee in full

extension (A) and flexion (B).

Epicondylar

Posterior condylar axis

gaps are equal in both flexion and

extension, no further lateral stabilizer

releases are necessary However, if

there is even a modest residual

val-gus deformity or instability, then

some lateral release may be required

There is no consensus regarding

the sequence in which the

struc-tures about the knee should be

re-leased.12,13,18-20 Those structures

most commonly addressed for

re-lease include the iliotibial band,

pos-terolateral capsule, lateral collateral

ligament (LCL), popliteal tendon,

and the lateral head of the

gastroc-nemius muscle

Krackow and Mihalko21 and

Krackow et al22 developed a

kine-matic analysis model of the

com-monly released lateral structures in

a cadaveric model After release of

the LCL, popliteus, lateral

gastroc-nemius, and iliotibial band, <5

degrees of correction could be

achieved in full extension if the

pos-terior cruciate ligament (PCL) was

retained If the release of the four

lateral structures was combined

with PCL sacrifice, a 9-degree

cor-rection could be achieved Releasing

the LCL first allowed for a more

gradual correction, with about 4

degrees obtained after initial LCL release and a gradual increase to about 9 degrees with release of suc-cessive secondary structures Be-cause the LCL is the primary stabi-lizer of the lateral side of the joint, release of the secondary stabilizers (iliotibial band, popliteal tendon, posterolateral capsule) before the LCL may result in insufficient cor-rection Subsequent release of the LCL may then result in overcorrec-tion and instability

However, some surgeons think that releasing the LCL first is inap-propriate They may be correct, de-pending on when in the range of motion the joint remains tight If the lateral side of the joint is tight in both extension and flexion, then subsequent release of the LCL must

be performed to balance the joint gap properly throughout a range of motion.19 If the joint gap is tight lat-erally only in extension, then release

of the iliotibial band or possibly the popliteus may correct the balance in extension Conversely, if the lateral joint gap is tight only in flexion, that deformity may be corrected by releasing the posterolateral capsule and popliteofibular ligament to equalize the flexion gap All of these releases are typically done after PCL sacrifice

Another method of progressively releasing the lateral side involves using multiple small incisions with

a scalpel blade through the taut pos-terolateral capsule with the knee in full extension.23 This technique may place the common peroneal nerve at risk The effectiveness of this method for achieving release has been eval-uated in both the preclinical and clinical settings With the lateral side of the knee joint and LCL pro-tected, the posterolateral capsule was incised, and effective correction occurred only after the LCL was divided and essentially released

This same technique was then ana-lyzed in the laboratory using cadav-eric kinematic analysis It was

evi-dent that <4 degrees of correction could be obtained if only the pos-terolateral capsule were released without the LCL.23 In addition, the common peroneal nerve was found

to be between 7 to 9 mm from the posterolateral capsule in full exten-sion These measurements were made, however, in cadaveric knees without deformity and therefore without contracted lateral anatomic structures The distance from the peroneal nerve to the posterolateral capsule may be even smaller

If release of the lateral structures does not sufficiently stabilize flexion and extension gaps, then the medial side of the joint should be addressed Several techniques have been de-scribed for successfully and safely

“tightening” the incompetent medial collateral ligament (MCL) Krackow

et al5described MCL advancement off the tibial side, and Krackow24

described MCL midsubstance divi-sion and imbrication, to equalize the joint gaps (Fig 4) Healy et al2 de-scribed recessing the origin of the MCL with a bone block from the femoral epicondyle Although these procedures are technically demand-ing and may affect ligament strength and isometricity, they may be neces-sary to equalize joint gaps to achieve

a stable and durable result

Component Selection

Another important consideration in the management of valgus defor-mity is prosthesis selection with regard to the degree of component constraint Ideally, if proper soft-tissue balance is restored, a mini-mally constrained component then can be implanted Although most surgeons agree that a more con-strained posteriorly stabilized com-ponent should be used if signifi-cant deformity necessitates PCL sacrifice for soft-tissue balancing, it

is not universally accepted Such a prosthesis provides some degree of posterior stabilization as well as protection against posteromedial,

Figure 3 Improper soft-tissue balancing

with a lax medial soft-tissue sleeve (A) that

allows opening of the joint in distraction

(B) or under a valgus-directed force.

posterolateral, straight medial, or

straight lateral translation, but it

will not protect against residual

medial laxity, which is one of the

major considerations in achieving

proper balance

The surgeon should resist the

temptation, when possible, to move

to a more highly constrained

pros-thesis, such as a totally stabilized

prosthesis, to compensate for

short-comings in achievable soft-tissue

balancing Although highly

con-strained components may be

neces-sary in difficult revision cases, they

are infrequently necessary for

pri-mary TKA The patient with severe

valgus knee deformity also may

have a stretched or elongated PCL

because of the more medial position

of the PCL Therefore, even if the

PCL is retained in a severely valgus

knee, it may be nonfunctional and

require either an ultracongruent or

posteriorly stabilized component

Component selection for the

val-gus knee with an extremely

defi-cient lateral femoral condyle may require the use of component aug-mentation if the femoral component

is being cemented The lateral fem-oral condyle may have had little or

no distal femoral bone resected or, similarly, little to no bone resected from the chamfer and posterior cuts, as well These cuts may require component augmentation However,

if the femoral component is being press-fit, then as long as native bone

is resting on one of the chamfer cuts (as is usually the case for the poste-rior bevel or chamfer cut), then the remaining defect can be filled with autograft bone taken from other cuts during the procedure.8

Surgical Technique

After surgical exposure of the joint and débridement of osteophytes, a tension-stress examination is per-formed with the knee in full exten-sion and the tibia distracted from the femur Small-arc varus and val-gus forces are applied to assess

when the medial and lateral aspects

of the soft-tissue sleeve are equally taut With the tibia held steadily at this point, an approximate assess-ment of the overall alignassess-ment and existing tibiofemoral angle can be made In this way, it is possible to make an initial estimate of the de-gree of soft-tissue sleeve asymme-try, which will need to be managed

by “balancing.” Next, the general shape of the distal femur is assessed Both the AP axis of Whiteside and the epicondylar axis are used In some cases of valgus deformity, the lateral epicondyle is not prominent, and defining a distinct lateral point for the axis may be imprecise With these axes in view, the amount of posterior femoral condylar

deformi-ty is estimated

The knee is then extended and the presence of any flexion contracture or recurvatum can be assessed The se-verity or degree of these two features may affect the relative proximal-distal positioning of the proximal-distal fem-oral cut With most modern cutting jigs positioned to guide the distal cut, one expects the jig to encounter the more prominent distal medial condyle and thus to stand posi-tioned more distally, away from the lateral condyle This examination allows a rough estimate of wear or deformity of the lateral femoral condyle distally The knee is then fully extended, and the cut is refer-enced from the more distal (usually medial) condyle In the presence of

a flexion contracture not completely addressed by capsular release, a somewhat more proximal cut may

be made In the valgus knee with such asymmetric presentation, the decision whether the distal cut should be referenced from the prom-inent condyle, the deficient condyle,

or somewhere in between is made based on the situation of the knee at its maximum extension When the knee comes to full extension, the cut

is referenced from the more distal (usually medial) condyle In the

Figure 4 A, The epicondylar origin in this lax MCL is represented by the cross-hatched

circle B, The MCL is removed from the epicondyle and is advanced to remove the laxity.

C, A running locking nonabsorbable suture is then used to secure the ligament in its new

position, and a surgical staple is placed at the epicondylar origin (Adapted with

permis-sion from Krackow KA: Management of medial collateral ligament loss: Repair and

aug-mentation, in Lotke PA, Garino JP (eds): Revision Total Knee Arthroplasty Philadelphia, Pa:

Lippincott-Raven, 1999, pp 227-250.)

presence of a flexion contracture not

likely to be completely addressed

by capsular and/or osteophyte

re-lease, a somewhat more proximal

cut may be made In the rare case of

initial recurvatum, an even more

distal cut may be necessary

Alter-natively, a smaller component can

be selected in an attempt to increase

the flexion gap to match the larger

than normal extension gap that

allows recurvatum to occur

The distal femoral cut is oriented

so that it is perpendicular to the

mechanical axis of the femur, i.e.,

the center of femoral head to the

center of the distal femur Usually,

the anterior and posterior femoral

cuts are made first; however, it is

acceptable to perform the tibial cut

first and then proceed with most or

all of the soft-tissue release The

amount of valgus alignment in the

distal femoral cut is determined

from preoperative, long-standing

radiographs (Fig 5, A) by

measur-ing the angle between a line along the femoral diaphysis through the center of the knee, and one from the center of the knee to the center of the femoral head (Fig 1, A)

After the tibial cut and soft-tissue release, one may assess the rotational position of the femur as it is dis-tracted away from the tibia with the knee in flexion Although the final determination of the anterior and posterior femoral cuts can be based entirely from the tibia, attempting to make a perfectly rectangular 90-degree flexion space can be danger-ous Within limits, it may be possi-ble to achieve greater symmetry of the flexion space by some minor ro-tational alterations in accordance with the relative orientation of the cut tibial surface The amount of tib-ial resection is usually first gauged from the more prominent side (usu-ally medial), ignoring an erosive de-fect if one is present If the eroded lateral tibial compartment does not allow rim contact, then one can in-crease the size of the cement man-tle or increase the amount of resec-tion until adequate support results

This usually does not require any significant amount of added resec-tion

Generally, we position the fem-oral instrumentation first to select component size and then perform the anterior and posterior femoral cuts Many jigs utilize “skids,”

which contact the posterior femoral condyles, and then use some scheme for off-setting the rotational axis

After assessing the component rota-tion as determined by the instru-mentation, we recheck and confirm that orientation with the Whiteside axis and, if reliably visible, with the epicondylar axis Any single refer-encing technique or combination of techniques would then be selected and the remaining femoral cuts made

Deciding when to begin and com-plete soft-tissue balancing is influ-enced by surgeon preference and

the degree of deformity If a sub-stantial release is necessary, it may

be more appropriate to perform this earlier in the procedure Repeat evaluation of joint gaps and balance

is of paramount importance after each individual structure is divided The first step is to assess the lateral and posterolateral corner of the knee

to determine tension in the iliotibial band Occasionally, but rarely, the iliotibial band may appear to be the tightest structure; it would therefore require release first More commonly, the LCL is the tightest structure and is released initially The LCL is sharply elevated from the lateral epicondyle until it is completely released During the LCL release, the popliteal tendon should be iden-tified and protected to avoid inad-vertent division The effect of the LCL release is then assessed by a tension-stress examination in full extension, partial flexion, and 90 de-grees of flexion It is helpful to place

a tagging suture on the stump of the LCL for future identification

The next release is that of the popliteal tendon, either at or near the joint line Any bridging connections between the popliteus and the LCL

or tibia are separated At this point, there will be definite opening of the lateral aspect of the knee, more pro-nounced in flexion than extension Other structures that may require release include the posterolateral capsule and femoral origin of the gastrocnemius muscle complex, especially in the setting of flexion contracture Finally, the iliotibial band can be considered Release of the biceps femoris tendon and/or exposure of the peroneal nerve gen-erally is not recommended

If both the LCL and the popliteal tendon have been released, they are

“repaired” to one another with a locking-loop ligament suture for maximum strength The purpose of this repair is to provide support in flexion to avoid excessive lateral gapping Release of both the LCL

Figure 5 A, Thirty-six-inch long-standing

preoperative radiograph of valgus

defor-mity B, Postoperative thirty-six-inch

long-standing radiograph after TKA, showing

restoration of proper mechanical

align-ment.

and popliteus from the lateral

fem-oral epicondyle, as described by

Insall,13has been successful without

secondary lateral flexion instability

Even the patient who undergoes a

release of all lateral structures to

balance the knee does not need

ad-ditional care postoperatively beyond

that of a routine TKA, except for the

addition of a knee brace

If initially there was felt to be

stretching of the medial capsular

ligamentous complex, it may be

impossible to balance the knee by

addressing only the lateral side In

this situation, utilization of a

tech-nique to tighten the ligamentous

structures of the medial side and/

or the use of a more highly

con-strained intercondylar prosthesis

(nonhinged) may be appropriate

Advancement of the MCL, as

previously described5 (Fig 4), or

division and imbrication of the

MCL24(Fig 6), can be done in

con-junction with use of a constrained

intercondylar prosthesis to protect

against gravity distraction of the

leg and dissociation of the

intercon-necting peg This is a very simple

technique, which together with the

constraint of the prosthesis requires

no alteration of patient aftercare

Complications

Results of past clinical studies,2,3,5-9,25

clearly indicate that several compli-cations have been reported more fre-quently in this subset of patients

The most commonly reported com-plications in patients with valgus deformities who undergo TKA are tibiofemoral instability (2% to 70%), recurrent valgus deformity (4% to 38%), postoperative motion deficits requiring manipulation (1% to 20%), wound problems (4% to 13%), patel-lar stress fracture or osteonecrosis (1% to 12%), patellar tracking prob-lems (2% to 10%), and peroneal nerve palsy (3% to 4%).2,3,5-9,25

Idusuyi and Morrey25 reported 32 postoperative peroneal nerve palsies

in more than ten thousand consecu-tive TKAs Of the 32 palsies, 10 knees had 12 degrees of preopera-tive valgus deformity or more This problem presumably is caused by lengthening the lateral aspect of the knee during lateral stabilizer release and subsequent traction to the pero-neal nerve It is generally recom-mended that patients be evaluated carefully for symptoms postopera-tively If peroneal nerve palsy–type symptoms are discovered, the knee

should be flexed to relax the tension that is effectively being placed on the nerve There are no objective guidelines or data to support the efficacy of any immediate surgical intervention

Clinical Results

Krackow et al5retrospectively re-viewed 99 arthroplasties for valgus knees in 88 patients and compared them to a control group with mini-mal deformity They identified three types of valgus knees: type I had a valgus deformity secondary to bone loss in the lateral compartment with medial soft-tissue contracture; type

II had obvious attenuation and in-competence of the medial compart-ment; and type III was the result of

an overcorrected proximal tibial os-teotomy for varus deformity All arthroplasties were performed with

a minimally constrained PCL-sparing prosthesis Type I patients were treated with lateral soft-tissue re-lease only, and type II patients were treated with lateral soft-tissue re-lease and MCL advancement No type III patients were treated Post-operative rating scores for

align-Figure 6 Imbrication of the MCL can also be used to equalize the joint gap A, Two running locking sutures are placed with the amount

of ligament to be imbricated represented by the distance between the two suture ends B, The MCL is then transected between the two running locking sutures C, The respective suture ends are tied together to complete the imbrication (Adapted with permission from

Krackow KA: Management of medial collateral ligament loss: Repair and augmentation, in Lotke PA, Garino JP (eds): Revision Total Knee Arthroplasty Philadelphia, Pa: Lippincott-Raven, 1999, pp 227-250.)

ment and function were equivalent

for both type I and II patients There

were more fair (7%) and poor (2%)

results in the study group compared

with the control group The authors

stated that ligament reconstruction

was effective and was important in

knee stability even when more

con-strained prostheses are used

Stern et al7reviewed 134

arthro-plasties in 98 patients with valgus

deformity of >10 degrees

Eighty-seven percent of patients were

treated with a posteriorly stabilized

prosthesis Ligamentous balancing

was done with sequential releases

from the lateral side of the femur

only and did not include medial

ligament reconstruction The knees

were stratified into subgroups

based on the severity of

preopera-tive deformity The postoperapreopera-tive

alignment goal was 5 to 9 degrees

of valgus At an average follow-up

of 4.5 years, 91% of patients had

good or excellent results The

authors recognized the difficulty of

achieving proper femoral

compo-nent rotation because of the

defi-cient lateral femoral condyle and

concluded that a constrained

femoral component is necessary for

the severe valgus knee

Laurencin et al6retrospectively

reviewed 25 arthroplasties in knees

with an average preoperative valgus

deformity of 25 degrees In all

pa-tients, a lateral retinacular release

was performed The remaining

lat-eral structures were released as

needed to achieve proper soft-tissue

balancing Twenty-one of 25

pa-tients had an unconstrained

PCL-retaining prosthesis Twenty-four of

25 patients had postoperative

ana-tomic valgus alignment of 0 to 10

degrees Postoperative flexion

aver-aged 110 degrees, and average

flex-ion contracture measured 2 degrees

(range, 0 to 12 degrees) There were

significant complications in nine

knees, including patellar fractures

secondary to osteonecrosis (three

knees), patellar instability (one),

per-oneal nerve palsy (one), and recur-rence of deformity (one) The au-thors underscored the importance of soft-tissue balancing and preserving the superior lateral geniculate artery when performing a lateral release in conjunction with a medial parapatel-lar approach

Whiteside8 reviewed 135 knees with valgus deformity treated with

a minimally constrained prosthesis

Seventy-one percent of patients with <25 degrees of preoperative valgus had a lateral ligamentous release In 11 knees with >25 de-grees of deformity, the deficient lat-eral condyle was used as a point of reference, resulting in overresection

of the medial distal surface Six of the

11 patients required medial ligament advancement to achieve stability in extension Mean postoperative val-gus was 7 degrees compared with

16 degrees preoperatively There was no deterioration of alignment postoperatively Knees with >25 degrees of preoperative valgus de-formity had an increased incidence

of posterior laxity Accurate bone resection, correct alignment, and bone graft to fill femoral and tibial defects were thought to be impor-tant factors in achieving good re-sults

Karachalios et al3performed a prospective case-control study com-paring severely deformed knees (defined as >20 degrees of varus or valgus malalignment) with

minimal-ly deformed knees All patients were treated with a minimally constrained PCL-retaining prosthesis The pa-tients demonstrated no significant difference in function postoperatively comparing the group with severe varus to that with valgus deformities

The authors did note a higher inci-dence of postoperative residual val-gus deformity and patellofemoral malalignment in the valgus group

They concluded that failure to obtain full correction of valgus deformity may lead to residual patellar tracking problems

Miyasaka et al9 reviewed 108 knees in 83 patients with an average follow-up of 14 years All patients were treated with a standardized sequence of soft-tissue releases from the lateral side, starting with the ilio-tibial band and lateral retinaculum, followed by the LCL and popliteal tendon when necessary Soft-tissue releases were performed before bone cuts were made Ninety-eight val-gus knees were reviewed, with 10 patients requiring a highly con-strained component because of excessive instability Postoperative results were deemed acceptable by the authors despite a 24% rate of knee instability As a result, a dif-ferent approach was subsequently developed, performing bony cuts first, followed by soft-tissue balanc-ing and pie-crustbalanc-ing of the iliotibial band

Healy et al2reviewed eight pa-tients with type II valgus deformi-ties (lateral soft-tissue contractures with lax medial soft-tissue stabiliz-ers) managed with MCL advance-ment Seven of eight patients had condylar, nonconstrained PCL-retaining components, and one had

a PCL-substituting implant Lateral structure releases included resection

of femoral or tibial osteophytes, division of the iliotibial band and popliteal tendon, and release of the arcuate ligament The MCL with a bone plug and incorporated liga-ment stitch was advanced proximally and laterally and tied over a button

or bony bridge on the lateral cortex Recession of the bone plug was thought to allow bone-to-bone heal-ing while isometrically tightenheal-ing the MCL At an average follow-up

of 5.8 years, all patients were satis-fied with the procedure, as demon-strated by decreased pain and by improved function Radiographic tibiofemoral alignment ranged from

3 to 7 degrees of valgus The authors consider this to be a simple and re-producible technique for eliminating MCL laxity during arthroplasty

The valgus knee presents a

chal-lenge to the joint replacement

sur-geon The principles of TKA must

be applied while taking into account

preexisting anatomic deformities

Understanding the femoral anatomy and using the AP axis for femoral component placement may help prevent postoperative patellofem-oral maltracking and instability

Recognizing the soft-tissue asym-metry and using the tension-stress

examination to evaluate this allows

a structured approach to proper bal-ancing As a result, the surgeon may more confidently achieve soft-tissue balancing, resulting in better load distribution and enhancing component stability and longevity

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