Kinematic Comparison Movement

MR Imaging ofPassive Techniques’

ofthe Patellofemoral Positioning and Active

the steady

Frank G. Shellock, PhD Jerrold H. Mink, MD Andrew L. Deutsch, MD Thomas K. F. Foo, PhD

quence

state

(GE

kee)

has been

cient

temporal

kinematic patients underwent magnetic resonance (MR) imaging of the patellofemoral joint in an evaluation of passive positioning and active movement

Thirteen

kinematic

MR

imaging

techniques.

Six-

teen joints were symptomatic, and 10 were not. Delineation of normal and abnormal patellar alignment and tracking was similar with the two techniques, but kinematic MR imaging performed with active movement allowed a substantial reduction in examination time while permitting evaluation of the contribution

of associated

activated

muscles and soft-tissue structures patellofemoral joint function. Index Knee,

terms: Knee, MR. 453.1214 cine study

(MR),

Radiology

1992;

abnormalities, Magnetic

184:574-577

of the patellofemoral joint related to incongruency between the patella and femoral trochlear groove are the frequent cause of patellar subluxation, patellar dislocation, chondromalacia, and arthrosis (1-5). magnetic

imaging

resonance

is a sensitive

(MR)

method

(6-14).

spoiled

Recently,

an ultrafast,

gradient-recalled

acquisition

in

passive achieved

positioning with the

Tower

bly.

Received

January

quested

March

accepted

March

F.G.S. C

574

RSNA,

1992

#{149} Radiology

described Medical transmit

and

Study

that

with

of the

msec, patients

a provisional

clinical

patellar

alignment

abnormal

were

evaluated.

increments

of

and

time

time

onds.

The

of joint

total

image

was approximately was

26 years). Patelhad been per-

three

different

entire

acquisition

flexion,

locations

excursion

of the

to evaluate

lateral retinacular releases, i = 4). Positioning device-A nonfenromag-

kinematic

active

imaging this

studies

device

restrict joints was positioning

(6-8,10,14).

is crucial

give

to displace

the

an erroneous

The

patient

lower

was placed

extremity

tamed

(ie, the

patient

was

between

the

on the

main-

observed

position

and

patient’s

the

feet

procedure

was

was

performed

receive

coil

quadra-

of a i.5-T

spoiled

64-MHz

Systems)

GRASS

previously

described

imaging

6.5/2.1; averages,

of view,

flip

parameters

38 cm; section

movements

of the lower

instructed to initiate active of the joints approximately after hearing the gradient

Systems,

RSNA 21, 1992;

5; revision 27. Address

Milwaukee scientific revision

received reprint

assemreMarch 16; requests to

occur

during

ral joints

flexion

(7,8,10),

because

excessive

rotation

may

abnormal

which internal

be partially

patellar

extremities

of the

alignment

to

patellofemo-

is important

then

or external

responsible and

movement with the

extended

rotational

for track-

thickness,

7

to perform this type of MR imaging with a fast low-angle shot pulse sequence (eg, turboFLASH; Siemens, Iselin, NJ). For kinematic MR imaging with the

scheme

allows

were

mm; acquisition time, 8 seconds for six images at a single section location (14). Alternatively, it would also be possible

positioning

Los Angeles

4X

angle, 30#{176}; number of one; matrix, 160 x 128;

90048 (F.G.S., J.H.M.,

Vicen-

GE

is required for MR imaging.)

Medicine,

444 5 San

an

sequence.

[14],

and software spoiled GRASS

MR

and

pulse

active began

Center,

(ie,

and

(GE Medical

hardware ultrafast

field

care to so that

was

imager

used: signal

of patel-

alignment

body

The following

unpub-

prone

groove Total examipositioning,

imaging

the transmit

tune

(As or

and

with special extremities

in an upright

of

may occur position is

appearance

device the lower

use

patella

with

ultrafast

anterior

lar subluxation (Shellock FG, lished observations, 1987). positioning position

MR

The

because

lateral direct pressure that with the patient in a prone sufficient

technique-MR

would

kinematic

imaging

the

in rela-

patient positioning, patient instructions, etc) was approximately 15 minutes. Kinematic MR imaging: active movement

device with a cut-out uninhibited movement or forces acting on the

movement

MR

it

in

patel!a

tion to the femoral trochlear during joint flexion (6-10). nation time for the passive

patellofemoral joints that motion) of the patellofemoral used for both the passive

time

and

sections

formed in five of the 16 symptomatic patellofemoral joints (medial transposition of the extensor mechanism, n = 1;

netic positioning area to permit (ie, no pressure

34 sec-

acquisition

to obtain

half;

38 cm;

4 minutes,

necessary

(500/

one

of view,

5 mm;

per degree

500

20 msec

averages,

x 128; field

thickness,

time

flexion,

(TR),

(TE),

of signal

256

section

five

eight women (26 patellofemo16 with symptoms of pateldisorders), and the age range (mean, surgeries

number

matrix,

track-

were

echo

spin-echo, performed at of joint

repetition

and

20);

diagnosis

There

as previously

coil was used. Ti-weighted, axial plane imaging was

Methods

subjects-Thirteen

of the

(6-8,10). A i.5-T 64-MHz (GE Systems) MR imager with a and receive quadrature body

as follows:

Materials

kinematics

maintained along with the relative amount of internal or external rotation of the lower extremities). This patient

Imaging

te Blvd. Los Angeles, CA A.L.D.); UCLA School of (F.G.S.); and GE Medical (T.K.F.F.). From the 1991

method versus active movement

the

at 5#{176} increments,

flexion

each

distance From

evalu-

technique.

while

I

of

to compare

of the patterns of patellar alignand tracking achieved with the

and

of evalu-

ating patellar alignment and tracking, as well as the anatomy of the patellofemoral joint (6-16). Examination of the patellofemoral joint with kinematic MR imaging is typically conducted by using a special device to passively position the joint in 5#{176} increments from extension to 30#{176} of flexion while Ti-weighted, spin-echo images are obtained at each of these positions

ation ment

patel-

The purpose

was

Also,

ing technique-The positioning device was used to passively move the pate!lofemoral joints from extension to 30#{176} of

performed

of the

(1,3,4).

patellofemoral joint are the same with prone and supine positioning (10). Kinematic MR imaging: passive position-

has suffi-

to be

(10,14).

was 14-37 years lar realignment

BNORMALITIES

Kinematic

imaging

joint

ing

to permit

movement

investigation

men and ral joints, lofemoral

453.421 resonance

#{149}

this

seMilwau-

that

resolution

active

lofemoral

pulse

Systems,

developed

MR

during

ing

to

(GRASS)

Medical

Joint:

technique, patellofemoral

positions.

to simultaneously

the

The patient

patient joints in

was

movement 1 second noise and

flex both

pate!-

lofemoral joints until the bottoms of their feet touched the top of the inside of the MR imaging system, and to leave

August

1992

b.

e.

f.

C.

Figure

were

1.

Axial

kinematic

obtained

MR

at the same

the patellae that trochlear grooves in a and b).

images

section

(500/20)

location

improves (ie, the patelbae are shallow, and a slight

them

in this

noise ticed

stopped (14). The patient practhis maneuver two or three times

without

imaging

movement tion ager

position

to ensure

was

was even operator

until

constant)

evenly

at

spaced

move into redundancy

the

(ie, that

mo-

to the

im-

through

the

described six images

that range

were of mo-

tion achievable within the bore of the magnet, and this procedure was repeated for three different section locations length joints

(14). Depending of the patient, could be flexed

within

the confines

system

(14).

The total image the aforementioned Volume

184

on the lower leg the patellofemoral up to 40#{176} or 45#{176}

of the MR imaging acquisition time with MR imaging pa-

Number

#{149}

2

joints

more centralized of the lateral

rameters

in a 23-year-old

was

positions) retinacula

approximately

and

woman,

Total

examination

during is evident

for the

ac-

tive movement kinematic MR imaging procedure, including time allotted for patient positioning, patient instructions, and practice runs, was approximately 7 minutes. Display, evaluation, and comparison of the kinematic MR imaging studies.-Images obtained during kinematic MR imaging with the passive positioning and active

movement

uated

as single-frame,

techniques

static

were

images

with

There

eval-

and

also were displayed as a cine loop (68,14,15). Compared with individual static images, evaluation of patellofemo-

ral joint

passive

is bilateral

the higher increments at the early increments

40 seconds

time

obtained

(f) 30#{176} of flexion.

(ie, one series to obtain images at six section locations during extension and three series to obtain six images at three section locations for thorough eva!uation of patellar alignment and tracking) (i4).

the previously rate of movement provided at a given section location Imaging

patellofemoral

at (a) 5#{176}, (b) 10#{176}, (c) 15#{176}, (d) 20#{176}, (e) 25,

gradient

that

acceptable and (14).

the

of the

positioning.

lateral

of joint flexion. of joint flexion

congruency

Images

subluxation

with

of

The femoral (arrowheads

the cine-loop

display is considered to provide the best qualitative information concerning the various patterns of patellar alignment and tracking (6-8,14,15). In addition, the cine-loop display of the images allows the determination of whether patellofemoral joint incongruency (ie, the position or positions of the relative to the femoral trochlear groove) identified during these studies improved, worsened, or remained the abnormal

patella

same during information

mine

joint flexion is considered

the severity

(6-8,14). to help

This

deter-

of the abnormality

(2,13).

Previously

ria and normal

were joints

described

qualitative

crite-

descriptions of normal and abpatellar alignment and tracking used to assess the patellofemoral (6-8).

Briefly,

normal

patellar

Radiology

575

#{149}

b.

e.

f.

C.

Figure

2.

the same of joint

Axial

MR

section flexion

images

of the

location is evident,

patellofemoral

and

in the same

and

the

joints,

patient

patterns

of the patellofemoral transverse

or lateral This

facets

ion,

causes

“centered”

the

relative

ral trochlear groove. of the patella occurs the patella is laterally

the lateral

facet

laps

the

aspect

lateral

trochlear eral

groove

pressure

acterized functional dominant

With ELPS, subluxation 576

to

femo-

groove femoral of the

(6,7,10).

10).

(ELPS)

lateralization, lateral patellar

groove

femoral

of the patella

is char-

with a

a small amount of lateral may occur during joint flex-

#{149} Radiology

movement

as increasing

taut

tracking

are

similar

tension

from

soft-tissue

displaces

kinematic

of the bilateral to those

one

or

structures

the

patella.

of the patellar

ridge

groove femora!

Lateral-to-medial

relative or the trochlea

subluxation

or centermost

part

Me-

to the center(6,7, is

In addition of patellofemoral qualitative tween the

and

tracking

medially of joint

to the above classification joint abnormalities,

comparison was made bepatterns of patel!ar alignment

shown

with

the passive

technique

(6.5/2.1;

lateral

subluxation

depicted

in Figure

positioning

flip

during

angle,

30#{176}) and

higher

at

increments

1.

method

versus

with

the

ac-

tive movement technique. This comparison was not performed in a “blinded fashion”; the viewing of the images from these two different studies, however, was performed randomly (ie, the evaluation of the images obtained with the passive positioning technique was not selectively performed before evaluation of images obtained with the active movement technique, or vice versa).

Results

of the femo-

ral trochlea and then displaces during the higher increments flexion (6,7,10).

lat-

usually onto facet (6,7,10).

and

overly

active

improvement

displayed when there is a slight-to-moderate lateral subluxation of the patella during the early increments of joint flexion; as flexion continues, the patella moves across the femoral trochlear

over-

Excessive

alignment

femoral trochlear most part of the

or the trochlea

of the patella

syndrome

by tilting

ment

medial

patella

1. The

the

dial subluxation of the patella, or patella adentro, is shown by medial displace-

(6,7,10,16). to the

with

progressively

Lateral subluxation when the ridge of displaced relative

to the femoral trochlear centermost part of the

and

more

without of the

of the patella

orientation

appear

joint,

displacement

as in Figure

of patellar

alignment and tracking is displayed with the ridge of the patella positioned in the femoral trochlear groove as it travels in a vertical plane during flexion

obtained

Technically

acceptable

images

were

obtained in all patients examined investigation. Ten patellofemoral were normal, and these were the 10 joints

that

were

asymptomatic.

in this joints same Of

the pate!lofemoral joints that were symptomatic, six had lateral subluxation of the had

pate!la, medial

two subluxation

had

ELPS,

and

of the

eight

patel!a.

August

1992

None of the patellofemoraljoints lateral-to-medial subluxation

tella.

showed of the pa-

Of the five patellofemoraljoints

which

a surgical

realignment

ments,

in procedure

including

should

had previously been performed, one had lateral subluxation of the patella and four had medial subluxation of the patella. Delineation of each of the forms of patellar alignment and tracking patterns with the passive positioning technique (Fig 1) was comparable with that achieved with active movement kinematic MR imaging (Fig 2), such that norma! patellar alignment and tracking, lateral subluxation of the patella, ELPS, and media! subluxation of the patella were similarly shown with each method for each patellofemoral joint.

be noted

tative

criteria

passive

Abnormal

conditions

of

ment and tracking begin liest portion of the range this joint, as the patella ulates with the femoral (2,7,i3,i6,i7).

creases,

As

the

enters and antictrochlear groove

flexion

patella

patel!ar alignduring the earof motion of

of the

moves

joint

deeper

into

(2,6,7,10,13-15,17). alignment and

shown technique

with the paswere similar

to those shown with the active movement kinematic MR imaging method. The image quality of the kinematic studies

performed

with

the

ultrafast

spoiled GRASS pulse sequence was adequate to show the anatomy of the bone, as

well

as

the

soft-tissue

structures

asso-

dated with the function of the pate!lofemoral joint (14). Previous radiographic studies comparing passive positioning techniques with dynamic imaging methods for assessment

have

of the

been

patellofemoral

performed

son of ultrafast static skyline

show good quantitative

(12,15).

joint

Compari-

CT views with single, views has been reported

correlation between certain patellofemoral measure-

methods relationships

2

and in this

tracking

to compare

to

the

none

of the

matic

MR imaging

with

studies

were

3.

4.

patellofemoral to be completely

observed

passive

with

5.

system

The results of kinematic

(GE

Medical

showed that MR imaging

respect

to the

6.

active-

Systems).

patel-

Acta Orthop

Scand

in the rabbit.

1989; 60:188-191. Shellock FG, Mink

1941; 12:319-

F, Frich LH. by patellar sub-

Acta Orthop

JH, Deutsch

of patellar

Scand

A, Fox JM.

tracking

abnormali-

ties using kinematic MR imaging: clinical experience in 130 patients. Radiology 1989; 172:799-804.

7.

8.

Shellock FG, Mandelbaum B. Kinematic MRI of the joints. In: MinkJH, Deutsch AL, eds. MRI of the musculoskeletal teaching file. New York: Raven, Shellock FG, Mink JH, Deutsch

Ferkel

RD.

system. A 1990. AL, Fox JM,

of patients with after lateral retinacutar release by kinematic magnetic resonance imaging of the patellofemoral joint. persistent

assess-

pate!-

joint during active movement by using ultrafast CT, Hyperscan MR imaging, or ultrafast MR imaging is considered to be advantageous, because the contribution of activated muscles and other soft-tissue structures to patellar alignment and tracking may be evaluated (i2,14,i5,i7). This results in a more physiologic examination of the patellofemora! joint. With respect to the specific use of ultrafast spoiled GRASS MR imaging to study the patellofemora!joint, the main advantages include a substantial reduction in overall examination time (compared with duration in the previously described method) (6), as well as the fact that there is no need for a sophisticated positioning device for passive flexion of the joint. Because the examination time for performance of kinematic MR imaging of the patellofemoral joint during active movement is relatively short, it is feasible to include this procedure along with routine MR imaging examination of the knee, since both procedures can be cornpleted within an acceptab!e time in the clinical setting. This would provide a more thorough, overall examination of the knee, which would be useful in cases of combined abnormalities (1-4) and in cases of suspected patellofernoral incongruency with signs and symptoms that mimic other types of internal derangernents of the knee. U

in recurrent

410. Moller NB, Moller-Larsen Chondromalacia induced

Evaluation

the two forms were similar

qualitative

relationships

M, NeliPatel-

lar dislocation. J Bone Joint Surg [Br] 1989; 71:788-792. Ficat RP, Hungerford DS. Disorders of the patello-femoral joint. Baltimore: Wilhams & Wilkins, 1977. Wiberg G. Roentgenographic and anatomic studies on the femoropatellar joint, with special reference to chondromalacia

luxation

movement kinematic MR imaging studies performed with a Hyperscan MR imaging

tTM, Osterman K, Kormano 0, Hurme M, Taimela S.

patellae.

kine-

with

compared

Kujala markka

lofemoral

active moveCT study, the

that

patterns

2.

quanti-

(i5). Furthermore, it was conthat the cine loop of the ultrafast CT views of patellar movement provided the best qualitative assessment of patellofemora! relationships (15). In a prior study performed by our group (12), the patellar alignment and

9.

Arthroscopy 1990; 6:226-234. Shellock FG, MinkJH, Fox J, Ferkel Friedman M, Molnar T. Kinematic imaging evaluation of symptomatic tients following two or more patellar

alignment 10.

surgeries

1:175. Shellock

JMRI

MR pare1991;

JH, Deutsch A, PressMRI of the joints: techniques and clinical applications. Magn Reson 1991; 7:104-135. Shellock FG, Mink JH, Deutsch AL, Meeks T, Fox J, Molnar T. Axial loaded stress views and kinematic M evaluation of

patellar

12.

(abstr).

R,

FG, Mink

man BD.

11.

Evaluation

symptoms

Kinematic

alignment

and tracking:

results

98 patellofemoral joints (abstr). 1990; 177(P):263. Shellock FG, Cohen MS, Brady

Pfaff JM. and

Evaluation

tracking:

matic MR imaging perscan

T, MinkJH,

of patellar

comparison

alignment

between

and “true”

MR imaging

(abstr).

in

Radiology

kine-

dynamic JMRI

hy-

1991;

1:148-149. 13.

14.

Kujala

UM,

Osterman

K, Kormano

M,

Komu M, Schlenzka D. Patellar motion analyzed by magnetic resonance imaging. Acta Orthop Scand 1989; 60:13-16. Shellock FG, Foo TKF, Deutsch A, MinkJH. Patellofemoral joint: evaluation during acfive

flexion

with

ultrafast

spoiled

GRASS

MR imaging. 15.

16.

Radiology 1991; 180:581-585. W, Phelan J, Kathol MH, et al.

Stanford Patellofemoral joint motion: evaluation by ultrafast computed tomography. Skeletal Radiol 1988; 17:487-492. Nordin M, Frankel VH. Basic biomechanics of the musculoskeletal system. 2nd ed.

Philadelphia: 17.

Lea & Febiger,

1989.

MinkoffJ, Fein L. The role of radiography in the evaluation and treatment of com-

mon anarthrotic lofemoraljoint. 8:203-260.

disorders Clin

of the patel-

Sports

Med

1989;

References Kummel 1980;

#{149} Number

used

of quantitating appears

BM.

lofemoral

184

although

pa-

and It

reliable cluded

1.

Volume

offset,

ment of the normal and abnormal lofemora!joint findings (12). Examination of the patellofemoral

this portion of the range of motion are best suited for identification of instabi!ity of the patellofemora!joint (2-4,6, 7,iO,i3-i5,i7). These imaging techniques include conventional computed tomography (CT), ultrafast CT, and ki-

tracking patterns sive positioning

were

ment techniques authors recognized

with

in-

the femora! trochlear groove. At that point, patellar displacement is less likely to occur, because the femora! trochlear groove functions to buttress and stabilize the patella (3,4,iO,i5,i6). Since patellofemoral incongruency is most likely to exist during the iitia! degrees of flexion of the patellofemoral joint, imaging techniques that show the patella and femoral troch!ear groove during

nematic MR imaging In this study, patellar

tangent

that,

positioning

positioning

Discussion

the

tellar tilt angle, congruence angle, lateral patellofemoral angles (i5).

The

diagnosis

derangements.

of patelPrimary Care

7:199-216.

Radiology

#{149} 577