coronal alignment - Semantic Scholar

CORONAL AFTER

ROBERT

ALIGNMENT

TOTAL

S. JEFFERY,

From

KNEE

REPLACEMENT

RICHARD

W. MORRIS,

Alexandra

Hospital,

Queen

ROBIN

A. DENHAM

Portsmouth

Maquet’s line passes from the centre of the femoral head to the cenfre of the body of the talus. The of this line from the centre of the knee on a long-leg radiograph provides the most accurate measure of coronal alignment. Malalignment causes abnormal forces which may lead to loosening after knee replacement. We report a series of 115 Denham knee replacements performed between 1976 and 1981 using the earliest design of components, inserted with intramedullary guide rods. Patients were assessed clinically and long-leg standing radiographs were taken before operation, soon after surgery and up to 12 years later. In two-thirds of the knees (68%) Maquet’s line passed through the middle third of the prosthesis on postoperative films and the incidence of subsequent loosening was 3%. When Maquet’s line was medial or lateral to this, an error of approximately ± 3#{176}, the incidence of loosening at a median period of eight years was 24%. This difference is highly significant (j = 0.001). Accurate coronal alignment appears to be an important factor in prevention of loosening. Means of improving the accuracy of alignment and of measuring it on long-leg radiographs are discussed. distance

On

an anteroposterior

the

centre

of the

long-leg femoral

head

radiograph, to the

centre

a line

from

of the

body

We

aligned between

of the talus normally passes through the middle third of the knee (Maquet 1972). If this is not the case after total

were

knee

alternate

side lead

replacement, and tensile to loosening

Bargren,

compression

forces

on the concave

forces on the convex side of the joint (Denham and Bishop 1978).

Blaha

and Freeman

(1983)

may

are subjected

total knee replacement, acceptable

to cyclical

eccentric

loading.

it is difficult

to obtain

consistently

tibiofemoral

tourniquet,

intramedullary

alignment by eye because drapes and subcutaneous fat. Externaijigs guide rods are required.

R. S. Jeffery, FRCS, Orthopaedic Registrar R. A. Denham, FRCS, Emeritus Consultant Department of Orthopaedics, Queen Alexandra Portsmouth, Hampshire P06 3LY, England.

Hospital,

At of the or

Cosham,

R. W. Morris, MSc, Lecturer in Medical Statistics Department of Public Health Medicine, United Medical and Dental Schools of Guy’s and St Thomas’ Hospitals, Guy’s Hospital, London Bridge, London SE1 9RT, England.

Correspondence

should

©

1991 British Editorial Society ofBone 0301-620X/91/5l85 $2.00 JBoneJoint Surg[Br] 1991 ; 73-8:709-14.

VOL.

73-B,

No. 5, SEPTEMBER

1991

and

Joint

before

years

median

Surgery

operation,

thereafter.

coronal

knee

replacements

follow-up

postoperatively

Maquet’s

alignment

on all these

films

to the incidence period

of eight

and

on

line was used and

to

the results

of loosening

after a

years.

PATIENTS

From 1976 to April 1981, a total of 139 Denham total knee replacements were performed at Queen Alexandra Hospital, Portsmouth under the care of the senior author using

(RAD)

standard

the

original

pattern

Of these, one patient emigrated and the radiographs have been lost. In 20 knees graphs were not taken before knees pre-operative the patients were

flexion

of components

and

a

technique.

of more

radiographs

infection

prospective Details are

than

or poor death

Excluding

with bilateral prostheses of one patient (2 knees) long-leg alignment radioor after operation. For 13

radiographs unable to

were

postoperative

be sent to Mr R. Jeffery.

1 15 Denham

.

taken

assess

studied

have been related

have demon-

strated in cadaver studies that eccentric loading of the tibial component caused failure at between a third and a half of the force required to produce failure by central loading, depending on the type of prosthesis and the position of the load. In the clinical situation, malaligned prostheses

have

with intramedullary guide rods, performed 1976 and 1981 Full-length standing radiographs

these

were not taken because stand or had fixed knee

20#{176}. No postoperative

made

of

general due

eight

condition.

to pulmonary

24 knees,

standing

knees

There

because

of

was

one

embolus.

the study

records for 102 patients with given in Table I. All patients

included

full

115 prostheses. were followed

709

R. S. JEFFERY,

710

up

until

revision,

death

or

a minimum

postoperatively. Forty-four patients unrelated to their knee replacement, patients

were

contacted

of eight died the

R. W. MORRIS,

R. A. DENHAM

years

from causes surviving 58

(68 knees).

METHODS

Operative technique. The Denham knee replacement uses intramedullary guide rods to achieve coronal alignment (Thacker and Fulford 1986). The femoral template has an 18 cm intramedullary stem and the femoral component has a similar intramedullary stem, tapering from a 30 mm x 10 mm oval to a 5 mm x 5 mm square section. The instruments used for include an intramedullary

preparation guide

has a central hole diameter intramedullary

which

when

set (Fig.

the cement

has

Table I. Details knee replacements

Female

of the tibial plateau rod : the tibial component

admits a full-length 6 mm guide rod, which is removed 1).

of the series

of 102 patients

: male

with

115

85:17

OA:RA

50:52

Age at operation Median

(years)

(range)

Interquartile

66 (21 to 85)

range

60 to 71 Fig. I

Previous

reconstructive

Knee

replacement

Tibial

osteotomy

5 4 3

Hiparthrodesis

I

femoral

Abnormal

Length

Follow-up.

also had a femoral

had pre-operatively,

years until All patients

in the

cement

Alignment weight extension,

or an increasing

and

osteotomy

been

assessed clinically and postoperatively and on

of the review to establish free, and whether function the same or had deterior-

of the tibial component there was pain associated

radiographs. equally

component.

they died or until the prosthesis was who were too old or frail to attend

were contacted at the time whether the knee was pain and movement had remained ated. Loosening occurring when

intra-

femoral

8 (0 to 12) 4 to 10

range

The patients

radiographically

a removable

(years)

(range)

one patient

with

rod, and two views ofthe

2

of follow-up

Interquartile

component

guide

2

fracture

Median

tibial

medullary

or tibial diaphyses

bowing

Previous

The

3

Benjamin osteotomy Hip replacement

Abnormal

alternate removed.

surgery

on both positioned

radiolucent

The patient feet,

was defined as with a fracture

with to face

line.

stands, the the

knees

trying to take in maximal

X-ray

tube

at

a

distance of 180 cm. A 100 mA, 0.05 second exposure is used at 100 to 115 kV, depending on leg thickness. The 105 cm X 35.5 cm Cronex film (DuPont) varies from

Fig. Measurements

THE

2

on an alignment

JOURNAL

OF BONE

radiograph.

AND

JOINT

SURGERY

CORONAL

High

Plus,

a single

knee

through will

exposure

and Each

Standard, produce

to High optimal

ALIGNMENT

AFTER

Definition so that images of the hip,

TOTAL

KNEE

and

the mid-medullary

are

drawn,

film

is displayed

on a large

viewing

screen

Alignment

end. Maquet’s femoral head

data

and Variation of tibiofemoral angle from 7#{176} valgus (degrees) Mean

Pre-operative

(n

=

1 1 5)

12.4

Postoperative

(n

=

1 1 5)

2.6

8-to

Distance

Maquet’s

of

the knee (mm)

Mean

(SD)

(8.9)

to

(2. 1)

are

the

9 (9)

E

line passes

within

Maquet’s

line passes

through

the knee.

Maquet’s

line passes

outside

the

PREOPERATIVE

Number

5045 4035 30 25 2015 10 5 0-

the

middle

third

alignment extension

of the knee.

Table III.

centre of the of the talus.

tibiofemoral

the

centre

2). The

of

angle the

image

wide, so Maquet’s of the knee when

angle, provided The combination

may introduce

to

confirm

Pre-operative

Pre-operative angle(degrees)

much

that

deformity

that the knee is ofrotation and

larger

errors.

the

alignment

film

related

to postoperative

25

5.6 valgus

(3.7)

18

4.9

(3.2)

22

7.7valgus

(3.1)

1 1 to 17 valgus

14

7.6 valgus

(3.4)

> 17 valgus

36

7.8

(2.9)

to 3 varus

l0valgus(normal)

analysis

In order

knees

angle from

-23 to -12

-11 to 0

0 to 11

12 to 23

24 to 35

36 to 46

47 to 58

59 to 70

71 to 81

82 to 155

TIBIAL

COMPONENT

Valgus

h_ Fig. Alignment

before

postoperatively,

73-B,

and

related

after

operation

to the width

No. 5, SEPTEMBER

1991

3 and

at a minimum

of the tibial

component.

of eight

years

of variance

p

=

on

valgus

0.005

to calculate angle

valgus

the error due to measurement different

films,

we

recorded

the

between the femoral mid-medullary line and a line the centre of the femoral head to the centre of the

This

rotation

D(mm) Varus

same

knee.

.1.

tiblofemoral

(SD)

of the

-35 to -24

was

angulation

Mean

( n 52)

8- 12 YEARS

-46 to -36

All leg

Number

one way

-81 -70-58 to to to -71 -59 -47

line the

tibiofemoral

> 3 varus

-161 to -82

tibia!

radiographic

Postoperative e (degrees)

Number

the

from each

(n115)

of knees

4to

VOL.

the body

of the

from (Fig.

bisect

films should therefore be taken in maxima! ; a lateral view was taken in this position in

each case, acceptable.

knee.

3 valgus

45 40 35 3025 2015 10 5 0-

line

2#{176} in the tibiofemoral fully extended (RWM).

11 (12)

Maquet’s

made

(D)

of the tibia

of its length

tibia! prosthesis is 70 mm through the middle third

knee flexion

U

then

distance

and which

line is drawn from the centre of the

to Maquet’s

of the passes

femur

points

distance D is 1 1 mm or less ; D is recorded as negative for varus angulation and positive for va!gus. An error of rotation of the limb of up to 20#{176} during radiography introduces a projectiona! error of less than

(SD)

42 (32)

3.3(3.4)

12yearfollowup(n52)

line

the centre

from

of

plateau

of

of the

through

of the bone at a quarter

Measurements Table II.

lines

passing

diameter

ankle. long

711

REPLACEMENT

should

of the femur

remain

constant

if the shape

and

is unchanged.

RESULTS

Before operation, through the middle third of the 1 15 radiographs. After operation, Alignment.

Maquet’s line passed knee in only 13% of the this was true of 68% of

the early radiographs and 65% of those taken at more than eight years after knee replacement (Table II and Figure 3). In these cases the corresponding tibiofemoral angle was from about 4#{176} to about 10#{176} valgus. The standard deviation for the measurement of the same angle on different films ofthe same patient was 0.8#{176}.

Table

III shows

that

failure

to achieve

accurate

R. S. JEFFERY,

712

R. W. MORRIS,

R. A. DENHAM

alignment in this early series occurred mostly in patients with pre-operative varus deformity. Twenty patients had

Table IV.

bowing

Maquet’s

or malunited

shaft

or

(Table outside in four

had

fractures

had

of the

previous

tibia!

or femoral

reconstructive

operations

middle Valgus

or varus

Total

Subsequent loosening. Eleven of the 1 15 knees (10%) had either been revised for loosening or showed definite clinical and radiological signs of loosening at follow-up. Only two of the 1 1 knees which loosened had been

p

(Fig.

4). between

Table

VI

and VII),

and

(p were

=

and

there

varus

or valgus

between

Within middle

third

Valgusorvarus

(Tables

osteoarthritis

Total p

and

0.001

=

(Fisher’s

Prostheses

which

loosened

Prostheses

which

did not

Maquet’s

line

(p = 0.05), significant.

but

The

78

2(3%)

37

9(24%) 11

exact

Varus

>35

Valgus Postoperative

I

TIBIAL

D (mm)

30

6

16

2

2

1

13

0

19

1

35

1

alignment

related

versus arthritis,

valgus, p = 0.05 ; osteoarthritis p = 0.09 (Fisher’s exact test).

postoperatively of

chi-squared

the

difference

loosening

when

with

9.43,

2 df;

corrected

and (RSJ).

not

postoperative p

for

deform0.01,


0.5). with 49 prostheses radiographically eight to 12 Scores for pain, function =

.

or the

present

alignment

and

the

although the two loose, unrevised prostheses and had the lowest marks (Fig. 5). A function

4

often

unsuccessful to subsequent

was

of pre-operative

=

reviewed clinically postoperatively

operative

_ Postoperative

arthritis

Loose

and the findings on examination were added to give the BASK score (Aichroth et a! 1978). We found no independent relationship between either the early post-

COMPONENT

Fig.

Rheumatoid

alignment, the effect of pre-operative significant (stratified chi-squared Clinical review. Forty-one patients were years

to diagnosis

Nwnber

Conversely,

VIII).

24 to 35

related

Loose

was independent

ity (stratified

12 to 3

test)

alignment

association

malalignment

0 to 11

to

Number

Loosening : varus versus rheumatoid

-11 to 0

related

Loosening

Osteoarthritls

loosen

Valgus

-23 to -12

alignment

loosening

Within middlethird

-35 to -24

test)

115

Varus

-

line

in five of the

Loose

loosening

0

: Maquet’s

of the prosthesis

postoperative

detect

0

alignment

third

Number

Loosening : varus versus valgus, p third, p=O.004; valgusversusmiddlethird, exact test)

in

713

Varus

Valgus

Table

REPLACEMENT

stems

with

valgus

in 87% of our pre-operative

Because of operative deformity components were

the

poor in some introduced.

justified

radiographs.

correction of severe preearly cases, modified tibia! These had a 1 5#{176} or 30#{176}

R. W. MORRIS,

R. S. JEFFERY,

714

polyethylene wedge on the undersurface to reduce the need for a wedge of cement on an eroded tibia! condyle. This wedge ofcement may fracture and lead to loosening. A 2#{176} or 4#{176} inclination

later added for severe intramedullary

of the surface

to these special prostheses pre-operative deformity. stem is now used

of the plateau

was

to overcompensate A permanent tibia! for cases with major

instability.

Who

needs

graphs

alignment

radiographs?

are expensive,

bulky

to measure,

but they are essential

assessment

of

prosthetic

these radiographs are deformity or a previous postoperative alignment and prognosis.

Alignment

to store

radio-

time-consuming

in the development

design. necessary operation. radiograph

and In

for

clinical

and practice,

patients with bony In all cases, a single is valuable for audit

CONCLUSIONS The

theoretical

the

middle

need third

for of

Maquet’s the

knee

line is

to pass

This

corresponds to an error of up to 3#{176} from the normal tibiofemoral angle of 7#{176} valgus. In practice, a much wider range of angles has been regarded as acceptable. there tibia! through

Our results is a highly

prosthesis difficult

for the Denham prosthesis confirm significant increase in loosening

that of the

component when Maquet’s line does not pass the middle third of the knee. Intramedullary guide rods are one of the best available methods of alignment, and enabled us to achieve this higher standard in over two-thirds of postoperative radiographs. Since the reported series, modifications to the

and

technique

cases.

have

Careful

study

improved

accuracy

of long-leg

of the lower

in

radiographs

the selective use of special components patients with previous injuries, operations

and

are necessary for or deformities

limb.

We thank Mr Wai Ng for his assistance with statistical presentation, Mrs L Blackwell and Mrs C McBride for clerical help, the photography and radiology departments at Queen Alexandra Hospital, Portsmouth and the medical illustration department at Southampton General

Hospital. One or for personal or indirectly been or will institution, the authors

more of the authors have received or will receive benefits or professional use from a commercial party related directly to the subject of this article. In addition benefits have also be directed to a research fund, foundation, educational or other non-profit institution with which one or more of is associated.

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