J Orthop Sci (2005) 10:457–465
DOI 10.1007/s00776-005-0936-2

Original article
Development and reliability of a standard rating system for outcome
measurement of foot and ankle disorders I: development ofstandard rating system
Hisateru Niki1, Haruhito Aoki1, Suguru Inokuchi2, Satoru Ozeki3, Mitsuo Kinoshita4, Hideji Kura5,
Yasuhito Tanaka6, Masahiko Noguchi7, Shigeharu Nomura8, Masahito Hatori9, and Shinobu Tatsunami101Department of Orthopaedic Surgery, St. Marianna University School of Medicine, 2-16-1 Sugao, Miyamae-ku, Kanagawa 216-8511, Japan
Department of Orthopaedic Surgery, Keio University, Tokyo, Japan3
Department of Orthopaedic Surgery, Koshigaya Hospital, Dokkyo University School of Medicine, Saitama, Japan
4
Department of Orthopaedic Surgery, Osaka Medical College, Osaka, Japan
5
Department of Orthopaedic Surgery, Sapporo Medical University, Hokkaido, Japan
6
Department of Orthopaedic Surgery, Nara Medical University, Nara, Japan
7
Department of Orthopaedic Surgery, Tokyo Women’s Medical University Medical Center East, Tokyo, Japan
8
Nomura Seikeigeka Ganka Clinic, Yamaguchi, Japan
9
Department of Orthopaedic Surgery, Tohoku University, Miyagi, Japan
10
Unit of Medical Statistics, Faculty of Education and Culture, St. Marianna University School of Medicine, Kanagawa, Japan
2

Abstract
Background. The aim of this study was to report the five scales
comprising the rating system that the Japanese Society for
Surgery of the Foot (JSSF) devised (JSSF standard rating
system) and the newly offered interpretations and criteria for
determinations of each assessment item.
Methods. We produced the new scales for the JSSF standard
system by modifying the clinical rating systems established by
the American Orthopaedic Foot and Ankle Society (AOFAS
scales) and the Japanese Orthopaedic Association’s foot rating scale (JOA scale). We also provided interpretations ofeach assessment item and the criteria of determinations in the
new standard system.
Results. We improved the ambiguous expressions and content
in the conventional standard rating systems so they would be
easily understood by Japanese people. The result was
five scales in total. Four were designed for use specificallyfor ankle-hindfoot, midfoot, hallux metatarsophalangealinterphalangeal,
andlessermetatarsophalangealineterphalangeal sites; and the fifth was for the foot and ankle
with rheumatoid arthritis. Furthermore, we described interpretations and criteria for determinations with regard toevaluation items in each scale.
Conclusions. Conventionally, the AOFAS scales or the JOA
scale have been separately applied depending on the sites ordisorders concerned, but it was often difficult to decide onscores during practical evaluations because of differing expressions in different languages and also because of ambiguityin the interpretation of each evaluation item and in scoring

Offprint requests to: H. Niki
Received: May 23, 2005 / Accepted: June 28, 2005

standards as well. JSSF improved these scales and added
definite interpretations of evaluation items as well as criteria
for the rating (to be reported here in part I). Because thesesteps were expected to improve the reliability of outcomes
assessed by each scale, we examined the reliability in scoresof the newly developed scales, which are reported in part II(in this issue).

Introduction
To provide a basis for evidence-based medicine (EBM)from estimating the therapeutic usefulness or efficacy inepidemiologic surveys and clinical studies, such estimates must be based on reliable evaluation criteria. In
Japan, the Japanese Orthopaedic Association’s footrating scale (JOA scale)1 developed in 1991 for thispurpose has been widely utilized in discussions of thetherapy of foot and ankle disorders. The JOA scaleassesses almost all foot disorders, including congenitalabnormalities, trauma, infection, paralysis, tumors, arthropathies, circulation disorders, and rheumatoid arthritis (RA). Sites assessed range from the toes to theentire foot, making it a convenient tool to assess a wide
area of the foot and ankle joints. Problems as to its
reliability have been pointed out, however, as some of
the items evaluated are unnecessary or unsatisfactoryfor particular disorders or sites.2
In 1994, the American Orthopaedic Foot andAnkle Society (AOFAS) developed rating scales for the458

H. Niki et al.: Development of JSSF scales

ankle-hindfoot, midfoot, hallux metatarsophalangealinterphalangeal, and lesser metatarsophalangealinterphalangeal sites, respectively.3 Unlike the JOA
scale, these scales categorized assessment sites into fourareas, and the evaluated items were classified into threemajor categories: pain, function, and alignment. Another distinctive point was that these scales included
items for both subjective and objective evaluation.
These scales are now widely used and have been established worldwide as benchmark standard rating scales
for the foot and ankle. However, during the evaluation
process examiners often waver when interpreting each
item or when deciding on scores because of ambiguity
within the instrument. Also, regrettably, they have notbeen inspected for validity and reliability; neither have
the JOA scales. Therefore, it has been pointed that they
could not be used as a basis for practicing EBM.4–7
The JOA, therefore, undertook strategies to establish
rating standards that use both doctors’ objective andpatients’ subjective rating scores with the hope that the
new standards would be appreciated internationally.
The Japanese Society for Surgery of the Foot (JSSF)
was also involved in this effort.
The purpose of Part I of this endeavor is to describe
novel rating standards for foot and ankle disorders, providing explanations of each evaluation item and detailed criteria for ratings.

JOA1 scale. Furthermore, we wrote interpretations andscoring criteria for each item in each scale to avoid
differing interpretations.
Our current four site-specific scales are a completely
novel and original Japanese version and are far from aduplicate of the AOFAS clinical rating system, as we
modified the expressions and content to suit Japanesepeople. We also added interpretation criteria for each
item and rating criteria, such as a pain scale, which werelacking in the AOFAS clinical rating system. This is why
the Committee on Rating Standards for Foot Disease of
the JSSF grouped together the five scales — comprisedof four site-specific scales and the RA foot and ankle
scale — and termed it the JSSF standard rating system.

Materials and methods

Ankle-hindfoot scale

The JOA launched the Preparatory Committee of Criteria for Diagnosis and Assessment in September 1999
and entrusted each of its member societies with suchtasks as improvement and revision of evaluation standards and inspection of their validity and reliability. JFFS
started the The Committee on Rating Standards forFoot Disease of the JSSF in June 2000, and the Committee subsequently had many discussions and meetings.
As a result, we translated into Japanese the four sitespecific criteria for evaluation3 of the AOFAS andrevised expressions and content to be more appropriate
for Japanese people. Modifying this system for use inJapan is justified. First, we considered it difficult to apply one criterion in an evaluation to cover the entire
foot and ankle. Second, site-specific evaluation criteria
were thought to be easy to use; and, lastly, we considered it difficult for the international community to appreciate evaluation criteria that differed greatly fromthose of the AOFAS clinical rating system,3 which areaccepted as the worldwide standard. However, because
it seemed more appropriate to assess the foot as a wholerather than in a site-specific way in patients with rheumatoid arthritis (RA) because of the features of thatdisease, we partially modified and supplemented theResults
The total score of each scale was set at 100 points. Eachobservation item was scored only from clinical findings
and included both subjective and objective evaluation
items. Each of the four scales (i.e., those for the anklehindfoot, midfoot, hallux, and lesser toes) were divided
into three major items, which were pain, function, andalignment. The scale for RA had five major items: pain,
deformity, motion, walking ability, and activities ofdaily living (ADL). In addition, interpretation and criteria for scoring accompanied each item.

Because inversion and eversion of the foot involve
the talocrural, talocalacaneal, talonavicular, and/or
calcaneocuboid joints, we evaluate the ankle andhindfoot as a complex; this scale deals with disorders ortrauma incurred in those areas. A total of 40 points are
assigned to pain, 50 to function, and 10 to alignment(Table 1).
1. Pain (criteria for scoring pain are shown in Table 2).
2. Function.
a. “Maximum continuous walking distance” is the
maximum distance a person can walk without abreak.
b. Gait abnormality is graded as follows: “none orslight,” “obvious” (walking possible but gait abnormality obvious), and “marked” (walking
difficult and gait abnormality obvious).
c. Sagittal motion score includes the total points forpassive flexion and passive extension in the sagittal plane. Motion is measured at the flexion position of the knee joint with the basic axis on thefibula and with the locomotion axis on the footsole. Grades are “normal or mild restriction”(range of ≥30°), “moderate restriction” (15°–29°),and “severe restriction” (<15°).

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459

Table 1. Ankle-hindfoot scale
Parameter

PointsPain (40 points)
None
Mild
Moderate
SevereFunction (50 points)
Activity limitations
None
Limitations on recreational activities
Some limitations on daily and recreational activities
Severe limitations on daily and recreational activities
Maximum continuous walking distance
600 m or more
400 m to less than 600 m
100 m to less than 400 m
Less than 100 m
Walking surfaces
No difficulty on any surface
Some difficulty on uneven terrain, stairs, inclines
Severe difficulty or inability to walk on uneven terrain, stairs, inclines
Gait abnormality
None or slight
Obvious (walking possible but gait abnormality obvious)
Marked (walking difficult and gait abnormality obvious)
Sagittal motion (flexion plus extension)
Normal or mild restriction (30° or more)
Moderate restriction (15°–29°)
Severe restriction (less than 15°)
Hindfoot motion (inversion plus eversion)
Normal or mild restriction (75%–100% normal)
Moderate restriction (25%–74% normal)
Severe restriction (less than 25% normal)
Ankle-hindfoot stability (anterior drawer, varus-valgus stress)
StableUnstable
Alignment (10 points)
Good, plantigrade foot, well aligned
Fair, plantigrade foot, mild to moderate degree of malalignment
Poor, nonplantigrade foot, severe malalignment

40
30
20
0
10
7
4
0
5
4
2
0
5
3
0
8
4
0
8
4
0
6
3
0
8
0
10
5
0

Table 2. Pain scale
Degree ofpain

Spontaneous or
during exercise

None
Mild

None
Sometimes while
in motion
Always while inmotionAlwaysModerate
SevereDuring daily life

Playing sports orwith heavy work

None
None

None
Mild pain

None
None

With every
movement
Can barely walkModerate

Sometimes required

Severe (infeasible)

Always requiredd. Hindfoot motion score is the total points for passive inversion and passive eversion. Motion ismeasured at the flexion position of the knee so thebasic axis is a vertical line toward the crus and thelocomotion axis is on the foot sole. “Normal or
mild restriction” denotes 75%–100%, “moderate

Measures against
pain (remarks)

restriction” 25%–74%, and “severe restriction”<25% of that on the normal side.
e. Ankle-hindfoot stability is evaluated by the presence or absence of instability at the anterior
drawer and under varus-valgus stress. “Stable”
indicates a firm endpoint at the anterior drawer

460

and under varus-valgus stress. “Unstable” indicates a soft endpoint.
3. Alignment. Plantigrade foot indicates that the footcan touch the ground with the sole when walking.
“Mild to moderate malalignment” is easily correctable, and “severe malalignment” is uncorrectable.
Midfoot scale
The midfoot scale is for disorders or trauma incurredin areas of the first to third cuneiform, second to third
cuneiform, and third cuneiform-cuboid, naviculocuneiform, naviculo-cuboid, or Lisfranc joints. A totalof 40 points are assigned to pain, 45 to function, and 15
to alignment (Table 3).
1. Pain (criteria for evaluation of pain are given in
Table 2).
2. Function.
a. Footwear. Designations are “can wear conventional (commercially available) shoes,” “comfort
footwear (limited selection of commercially available shoes) or shoe insert required,” and “modified shoes (specially ordered) or brace required.”

H. Niki et al.: Development of JSSF scalesb. “Maximum continuous walking distance” isdefined as the maximum distance a person canwalk without a break.
c. Gait abnormality is graded as “none or slight”
when there is no or minimal gait abnormality,“obvious” when the abnormality is evident
but walking is possible, and “marked” when
the abnormality is obvious and walking isdifficult.
3. Alignment. Plantigrade foot indicates that the footcan touch the ground by the sole when walking.
“Mild to moderate malalignment” indicates easily
correctable malalignment, and “severe malalignment” indicates uncorrectable malalignment.

Hallux metatarsophalangeal-interphalangeal scaleThehalluxmetatarsophalangeal-interphalangeal(MTP-IP) scale was devised for disorders or trauma
incurred in areas of the first metatarsal, proximal phalanx of the hallux, distal phalanx, and MTP and IP
joints. A total of 40 points are assigned to pain, 45 tofunction, and 15 to alignment (Table 4).

Table 3. Midfoot scale
Parameter
Pain (40 points)
None
Mild
Moderate
SevereFunction (45 points)
Activity limitations
None
Limitations on recreational activities
Some limitations on daily and recreational activities
Severe limitations on daily and recreational activities
Footwear requirements
Can wear conventional shoes
Comfort footwear and shoe insert required
Modified shoes or brace required
Maximum continuous walking distance
600 m or more
400 m to less than 600 m
100 m to less than 400 m
Less than 100 m
Walking surfaces
No difficulty on any surface
Some difficulty on uneven terrain, stairs, inclines
Severe difficulty or inability to walk on uneven terrain, stairs, inclines
Gait abnormality
None or slight
Obvious (walking possible but gait abnormality obvious)
Marked (walking difficult and gait abnormality obvious)
Alignment (15 points)
Good, plantigrade foot, well aligned
Fair, plantigrade foot, mild to moderate degree of malalignment
Poor, nonplantigrade foot, severe malalignment

Points
40
30
20
0
10
7
4
0
5
3
0
10
7
4
0
10
5
0
10
5
0
15
8
0

H. Niki et al.: Development of JSSF scales

461

Table 4. Hallux metatarsophalangeal-interphalangeal scale
Parameter
Pain (40 points)
None
Mild
Moderate
SevereFunction (45 points)
Activity limitations
None
Limitations on recreational activities
Some limitations on daily and recreational activities
Severe limitations on daily and recreational activities
Footwear requirements
Can wear conventional shoes
Comfort footwear and shoe insert required
Modified shoes or brace required
MTP joint motion (dorsiflexion plus plantarflexion)
Normal or mild restriction (75° or more)
Moderate restriction (30°–74°)
Severe restriction (less than 30°)
IP joint motion (plantarflexion)
No restriction
Severe restriction (less than 10°)
MTP-IP stability (all directions)
StableUnstable
Callus or clavus
No or asymptomatic callus or clavus
Painful callus or clavus
Alignment (15 points)
Good, well aligned
Fair, mild to moderate degree of malalignment
Poor, severe malalignment

Points
40
30
20
0
10
7
4
0
10
5
0
10
5
0
5
0
5
0
5
0
15
8
0

MTP, metatarsophalangeal; IP, interphalangeal

1. Pain (criteria for evaluation of pain are listed inTable 2).
2. Function.
a. Footwear. Designations are “can wear conventional (commercially available) shoes,” “comfort
footwear (limited selection of commercially available shoes) or shoe insert required,” and “modified shoes (specially ordered) or brace required.”b. MTP joint motion score is the total of points forpassive flexion and passive extension in the sagittal plane. Measurement is made so that the basic
axis is on the first metatarsus, and the locomotion
axis is on the first proximal phalanx. Designations
for restriction are “normal or mild” (range of≥75°), “moderate” (30°–74°), and “severe” (<30°).
c. IP joint motion is evaluated only by passive
flexion and is measured so the basic axis is on thefirst proximal phalanx, and the locomotion axis ison the first distal phalanx. With “no restriction”
flexion is possible at ≥11°, and with “severe restriction” flexion is possible only at £10°.
d. MTP-IP stability is observed from every direction.
“Unstable” indicates ease of dislocation.

e. Callus or clavus is assessed by the presence orabsence of pain. The whole foot sole and hallux
are evaluated.
3. Alignment. “Mild to moderate malalignment”
indicates easily correctable malalignment, and“severe malalignment” indicates uncorrectablemalalignment.

Lesser metatarsophalangeal-interphalangeal scale
The lesser MTP-IP scale is devised for disorders
or trauma incurred in areas of the second to fifth
metatarsus, proximal phalanx, middle phalanx, distal
phalanx, MTP, and PIP joints. A total of 40 points are
assigned to pain, 45 to function, and 15 to alignment(Table 5).
1. Pain (criteria for evaluation of pain are shown in
Table 2).
2. Function.
a. Footwear. Designations are “can wear conventional (commercially available) shoes,” “comfort
footwear (limited selection of commercially avail-462

H. Niki et al.: Development of JSSF scales

Table 5. Lesser metatarsophalangeal-interphalangeal scale
Parameter
Pain (40 points)
None
Mild
Moderate
SevereFunction (45 points)
Activity limitations
None
Limitations on recreational activities
Some limitations on daily and recreational activities
Severe limitations on daily and recreational activities
Footwear requirements
Can wear conventional shoes
Comfort footwear and shoe insert required
Modified shoes or brace required
MTP joint motion (dorsiflexion plus plantarflexion)
Normal or mild restriction (75° or more)
Moderate restriction (30°–74°)
Severe restriction (less than 30°)
IP joint motion (plantarflexion)
No restriction
Severe restriction (less than 10°)
MTP-IP stability (all directions)
StableUnstable
Callus or clavus
No or asymptomatic callus or clavus
Painful callus or clavus
Alignment (15 points)
Good, well aligned
Fair, mild to moderate degree of malalignment
Poor, severe malalignment

able shoes) or shoe insert required,” “modified
shoes (specially ordered) or brace required.”b. MTP joint motion score is the total points forpassive flexion and passive extension in the sagittal plane, with the measurement so the basic axis
is on the second to fifth metatarsi, and the locomotion axis is on the second to fifth proximal
phalanges. Ratings for restriction are “normal or
mild restriction” (≥75°), “moderate” (30°–74°),
and “severe” (<30°).
c. IP joint motion is evaluated only by passive
flexion, with measurements made so the basic axis
is on the second to fifth proximal phalanx, and thelocomotion axis is on the second to fifth middle
phalanx. “No restriction” indicates that flexion ispossible at ≥11°, and “severe restriction” indicatesthat flexion is possible only at £10°.
d. MTP-IP stability is observed from every direction.
“Unstable” indicates ease of dislocation.
e. Callus or clavus is assessed by the presence orabsence of pain on the whole foot and the hallux.
3. Alignment. “Mild to moderate malalignment” iseasily correctable, and “severe malalignment” isuncorrectable.

Points
40
30
30
0
10
7
4
0
10
5
0
10
5
0
5
0
5
0
5
0
15
8
0

Rheumatoid arthritis foot and ankle scale
All of the disorders and deformities caused by RA in
the forefoot, midfoot, and ankle-hindfoot regions are
objects of evaluation. Because the entire foot should be
evaluated in RA patients, the JOA scale1 formed thebasis for the evaluation in this system. We removed“muscle strength” and “sensory disturbance” and added
items related to ADL, resulting in five major items:
pain, deformity, motion, walking ability, and ADL. A
total of 30 points are assigned to pain, 25 to deformity,
15 to motion, 20 to walking ability, and 10 to ADL(Table 6).
1. Pain. “Continuous pain when walking” indicates persistent pain beginning at the initiation of ambulation
but the ability to walk continuously. “Unable to walkdue to pain” means the inability to walk because of
severe pain upon physical exercise but no pain atrest. “Severe pain at all times” means continuous
severe pain even upon rest.
2. Deformity.
a. Deformity is evaluated separately in theforefoot (hallux, lesser toes), midfoot, andhindfoot.

H. Niki et al.: Development of JSSF scales

463

Table 6. RA foot and ankle scale
General Pain (30 points)
None or mild
Mild, persistent pain when walking
Unable to walk because of pain
Severe at all times

30
20
10
0

Deformity (25 points)
Forefoot
None
SlightObviousMarkedHallux5310Lesser toes
5
3
1
0

Midfoot53
10

Hindfoot
10530Motion (15 points)
Hindfootb
10
50

Forefoot (MTP/IP joints)a5
30

NormalHalf or more of normalLess than half of normal

Walking ability (20 points)
No limitation
Able to walk outdoors, but only to stroll around home
Able to walk indoors, but unable to walk outdoors
Unable to walk

20
10
5
0

Activities of daily living (10 points)
Climbing or descending stairs
Sitting on heels
Standing on toes
FootwearJapanese-style toilet

Easy
2
2
2
2
2

Difficult
1
1
1
1
1

Unable00000RA, rheumatoid arthritisaForefoot (MTP/IP joints) is evaluated at a site that is limited in motion most severely among thehallux and lesser toesb
Hindfoot is evaluated for a motion that is most severely limited among such motions as
dorsiflexion/plantarflexion and inversion/eversion

b. Deformity of the MTP and IP joints of the hallux.
“Slight” means slight protrusion of the MTP joint
or a flexible (manually correctable) deformity.
“Obvious” denotes marked protrusion of the
MTP joint or a rigid (manually uncorrectable)
deformity of the IP joint. When the deformity istermed “marked,” the hallux overrides the second
toe or is a rigid deformity with a callus or ulcer on
the IP joint.
c. Deformity of the MTP, proximal IP (PIP), anddistal IP (DIP) joints of the lesser toes. “Slight”
designates a flexible (manually correctable) deformity; “obvious” is a rigid (manually uncorrectable) deformity; and “marked” is a rigid
deformity with ulceration.

d. Deformity of the hindfoot. “None” is the presence of only physiological calcaneus valgus. “Obvious” indicates an obvious calcaneus varus or
calcaneus valgus, although the entire surface ofthe foot sole touches the ground. “Marked” deformity means that the medial or lateral side of
the foot sole does not touch the ground.
3. Motiona. The forefoot (MTP/IP joints) is evaluated at thesite that is limited in motion most severely among
the hallux and lesser toes.
1) Hallux MTP joint score is a total of points forpassive extension and passive flexion in thesagittal plane and is measured with the basic
axis on the first metatarsal and the locomotion

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H. Niki et al.: Development of JSSF scales

Table 7. Scale for activities of daily living
Parameter
Climbing ordescending stairs
Sitting on heels
Standing on toes

Easy

Difficult

Placing one foot on stair
above/below the otherCan touch the entire dorsal
foot on groundCan stand on toes easily for 5 s
or more with one leg

Placing feet side byside at every step
Room between dorsal
foot and ground
Cannot stand on toes with one leg;can stand with bothlegs for 5 s or more
Shoes become misshapen becauseof foot deformity
Can bend knees fully, but heels are
not on the floor

Footwear

Can wear stylish shoes

Japanese-style toilet

Can bend knees fully withoutlifting heels

axis is on the first proximal phalanx. “Normal”
is ≥75°; “half or more of normal” is 30°–74°;
and “less than half” indicates <30°.
2) Hallux IP joint motion is evaluated only forpassive flexion. Upon measurement the basic
axis is on the first proximal phalanx, and thelocomotion axis is on the first distal phalanx.
“Normal”: plantar flexion is possible at ≥11°.
3) MTP motion among the hallux and lesser toes
is evaluated for passive flexion and passive extension in the sagittal plane, the scores ofwhich are totaled. Upon measurement, thebasic axis is on the second to fifth metatarsal,
and the locomotion axis is on the second to
fifth proximal phalanx. “Normal” is ≥75°; “halfor more of normal” is 30°–74°; and “less thanhalf” indicates <30°.
4) Second to fifth IP joint motion is evaluatedonly for passive flexion. Measurement of
motion is made so the basic axis is on the second to fifth proximal phalanx, and the locomotion axis is on the second to fifth middle
phalanx. “Normal”: plantar flexion is possibleat ≥11°.
b. Hindfoot is evaluated for a motion that is most
severely limited among such motions as dorsiflexion/plantarflexion and inversion/eversion.
1) Joint motion in the sagittal plane includes total
points for passive dorsiflexion and passiveplantarflexion. Motion is measured at theflexion position of the knee joint with the basic
axis on the fibula and with the locomotion axison the foot sole. “Normal” is ≥60°; “half ormore of normal” is 30°–59°; and “less thanhalf” is <30°.
2) Hindfoot motion score is the total points forpassive inversion and passive eversion. Measurement is made with the knee flexed so thebasic axis is a vertical line toward the crus, andUnableUnable without help
Unable to sit on heels
Unable to stand on
toes even with both legs
Can wear only modified shoes(orthopedic shoes)
Cannot squat down

the locomotion axis is on the foot sole. “Normal” is ≥60°; “half or more of normal” is 30°–59°; and “half or less than normal” is <30°.
4. Activities of daily living (the scale for ADL is shownin Table 7).

Discussion
The foot and ankle refer to a wide area from the distal
phalanx of the foot to the distal end of the leg. Eachportion consists of many bones, joints, ligaments,
ligamentous symphyses, and intrinsic and extrinsic muscles. In addition, disorders or trauma of the foot andankle are so varied that evaluation of a limited area is
not always adequate when the evaluated area represents only part of the expression of a systemic condition
such as paralytic disorders and RA. Thus, it is difficult
to evaluate such conditions appropriately using only
one scale.
The AOFAS clinical rating system3 consists of foursite-specific scales that enable a focus on target sites or
diseases. Observation items are relatively simple andhave been translated and interpreted by attending
medical staff (examiners) for wide use in Japan. However, some items are not sufficiently straightforward forinterpretation or rating in the AOFAS clinical rating
system. For instance, for the item pain, to which as
many as 40 of the full 100 points are assigned, criteria
for evaluation are so ambiguous as to produce a rating
bias among examiners that may greatly influence
results. For the item function, the maximum walking
distance is expressed in blocks, a term not familiar to
Japanese. Also, the definition of gait abnormality andstability is not clear. Description of shoes is also difficult
to understand in the Japanese translation. Additionally,
for the item of alignment, the expression is so confusing
as to cause difficulty with evaluation. To solve these
problems, in part I of the present study (describedH. Niki et al.: Development of JSSF scales

herein) we describe in detail the interpretation andevaluation criteria of each item to provide Japaneseexaminers more understandable standards and to minimize differences in results among examiners.
It is difficult to cover the entire disease spectrum bysite-specific rating systems of disorders for which theentire foot must be assessed, such as RA. In such a case,
the JOA scale1 is useful because it covers a disorder orsites over a wide range. This scale, however, includes somany items that the number of points assigned to each
item is small, making a comparison difficult between
treatments or between cases. Interpretation and criteria
for rating each item are indefinite, as with the AOFAS
clinical rating systems, leaving the final decision to thediscretion of the examiner. Therefore, in the RA footand ankle scale that we devised in this study, we removed the items “muscle strength” and “sensory disturbance,” which are usually not applicable to RA, andadopted five major items: pain, deformity, motion,
walking ability, and ADL as evaluation items. We increased the number of points for each item and provided details of interpretation and evaluation criteria.
This change is expected to improve the reliability ofoutcomes evaluated using each scale.
A rating standard must be reliable not only as a rating
scale but to perceive the target disease or therapy properly. Defining interpretations and rating criteria ofevaluation items cannot always guarantee an improvement in inter- and intraexaminer reliability. It is necessary to test reliability for a standard to be recognized as
evidence. Many tests have been conducted on the reliability of rating criteria in the field of orthopedic surgery.8–16 The Committee on Rating Standards for Foot
Disease of the JSSF tested five scales (JSSF standard
rating system) for intra- and interexaminer reliability ina multiinstitutional study. The results of this study arereported in part II (in this issue).

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