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Knee Injury and Osteoarthritis Outcome Score for Children

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Purpose

The Knee Injury and Osteoarthritis Outcome Score for Children (KOOS-Child) is a 48-item instrument designed to assess the patient’s opinion about their knee after a knee injury that can result in post-traumatic osteoarthritis. The KOOS-Child 2.1, updated in October of 2015, consists of 39 items.

Link to Instrument

Instrument Details

Acronym KOOS-Child

Area of Assessment

Activities of Daily Living
Pain
Quality of Life

Assessment Type

Patient Reported Outcomes

Administration Mode

Paper & Pencil

Cost

Free

CDE Status

Not a CDE -- last searched 10/2/2024

Populations

Pediatric Disorders

Key Descriptions

  • 39 items (KOOS-Child 2.1); 48 items (KOOS-Child 1.0)
  • 5 subscales: pain, symptoms, activities of daily living, function in sports and play, and knee-related quality of life
  • Each question gets a score of 0-4
  • A normalized score is calculated for each subscale: 0 indicating extreme symptoms and 100 indicating no symptoms
  • Maximum score = 100 per subscale

Number of Items

39 items (KOOS-Child 2.1); 48 items (KOOS-Child 1.0)

Equipment Required

  • Pen
  • Paper
  • Access to Questionnaire

Time to Administer

10-20 minutes

Required Training

No Training

Required Training Description

No training is required. The KOOS-Child is self-explanatory and can be administered in the waiting room or used as a mailed survey.

Age Ranges

Child

6 - 12

years

Adolescent

13 - 17

years

Instrument Reviewers

Alyssa Varsalona, SPT, CSCS

Le’Shaunda Jones, SPT

Kurtis Kepfer, SPT

Melisa Smith, PT, DPT

Jennifer Wiley, PT, DHS, DPT

Body Part

Lower Extremity

ICF Domain

Body Function
Activity

Measurement Domain

General Health

Professional Association Recommendation

None found -- last searched 10/2/2024

Considerations

  • The KOOS-Child is available in several languages. It has been validated in Danish, English, Finnish, Greek, Norwegian, Persion, Spanish, and Swedish. All versions are available on the KOOS Website ().
  • An adult version (KOOS) is also available

Pediatric Disorders

back to Populations

Standard Error of Measurement (SEM)

Children with Knee Disorders: (Ortqvist et al., 2014; n = 115; mean age = 13.0 (1.9) years)

  • SEM for pain subscale (n = 72): 5.69
  • SEM for symptoms subscale (n = 72): 8.14
  • SEM for ADL subscale (n = 72): 5.28
  • SEM for sports/play subscale (n = 70): 8.02
  • SEM for QoL subscale (n = 70): 7.59

 

Children with Stable Knee Conditions: (Van der Velden et al., 2019; n = 100; mean age = 15.0)

  • SEM for symptoms subscale (n = 59): 10.2
  • SEM for pain subscale (n = 59):  9.9
  • SEM for ADL subscale (n = 59):  8.9
  • SEM for sports/play subscale (n = 59):  16.9
  • SEM for QoL subscale: (n = 59): 10.5

Minimal Detectable Change (MDC)

Children with Knee Disorders: (Ortqvist et al., 2014)

  • MDC for individuals on pain subscale: 15.78
  • MDC for individuals on symptoms subscale: 22.56
  • MDC for individuals on ADL subscale: 14.64
  • MDC for individuals on sports/play subscale: 22.22
  • MDC for individuals on QOL subscale: 21.03
     
  • MDC for group on pain subscale: 1.86
  • MDC for group on symptoms subscale: 2.66
  • MDC for group on ADL subscale: 1.73
  • MDC for group on sports/play subscale: 2.66
  • MDC for group on QOL subscale: 2.51

 

Children with Stable Knee Conditions: (Van der Velden et al., 2019)

  • MDC for symptoms subscale: 28.4
  • MDC for pain subscale: 27.3
  • MDC for ADL subscale: 24.7
  • MDC for sport/play subscale: 46.9
  • MDC for QoL subscale: 29.2

Normative Data

Healthy Individuals Aged 8-17: (Baldwin, 2017; n = 166, male = 84)

Gender-specific Reference Data for KOOS-Child (8-17 years)

 

 

 

Mean

Standard Dev.

Median

Min;Max

n

Pain

 

Male

 

Female

 

 

95.7

 

92.2

 

 

10.7

 

14.0

 

 

100

 

100

 

 

44;100

 

28;100

 

 

84

 

82

Symptoms

 

Male

 

Female

 

 

 

95.8

 

93.1

 

 

8.3

 

11.4

 

 

100

 

100

 

 

57;100

 

43;100

 

 

84

 

82

ADL

 

Male

 

Female

 

 

99.1

 

96.4

 

 

3.4

 

7.6

 

 

100

 

100

 

 

75;100

 

52;100

 

 

84

 

82

Sport/play

 

Male

 

Female

 

 

97.8

 

93.2

 

 

5.8

 

13.7

 

 

100

 

100

 

 

71;100

 

43;100

 

 

84

 

82

QoL

 

Male

 

Female

 

 

97.3

 

94.4

 

 

7.2

 

13.7

 

 

100

 

100

 

 

54;100

 

13;100

 

 

84

 

82

Test/Retest Reliability

Children with Knee Disorders: (Ortqvist, 2014)

  • Excellent test-retest reliability for pain subscale (ICC = 0.87)
  • Excellent test-retest reliability for ADL subscale (ICC = 0.85)
  • Excellent test-retest reliability for sports/play subscale (ICC = 0.91)
  • Excellent test-retest reliability for QoL subscale (ICC = 0.85)
  • Adequate test-retest reliability for symptoms subscale (ICC = 0.78)

 

Children with Stable Knee Conditions: (Van der Velden, 2019)

  • Excellent test-retest reliability for symptoms subscale (ICC = 0.9)
  • Excellent test-retest reliability for pain subscale (ICC = 0.9)
  • Excellent test-retest reliability for ADL subscale (ICC = 0.9)
  • Excellent test-retest reliability for sports/play subscale (ICC = 0.8)
  • Excellent test-retest reliability for QoL subscale (ICC = 0.9)

Internal Consistency

 

Children with Knee Pathology: (Moutzouri et al, 2021; n = 59; male = 29; mean age: 11 (1.8) years; age range = 8-14; inclusion criteria: Greek as native language, able to understand/complete questionnaires, referred with confirmed knee pathology symptoms; Greek translation of KOOS-Child)

  • Excellent internal consistency for all KOOS-Child subscales (Cronbach’s alpha all > 0.8)

 

Internal consistency for KOOS-Child subscales (n = 59)

Subscale

Cronbach’s alpha

Pain

0.92

Symptoms

0.81

ADL

0.96

Sport-play

0.94

QoL

0.93

 

 

Patients with Knee Pain: (Rioux Trottier et al, 2018; n = 99 (21 in control group and 78 in knee injury group; inclusion criteria: age range = 8-16; French as native language; signed consent form; knee injury group: knee pathology diagnosed by an orthopedic surgeon; control group: no past or present lower extremity problems; French translation of KOOS-Child)

  • Poor to Excellent internal consistency (Cronbach’s alpha) by KOOS-Child subscale for Control and Knee Pain groups

 

Internal consistency for KOOS-Child subscales and total score for subject groups

Subscale

Cronbach’s alpha-Control (n = 21)

Cronbach’s alpha-Knee Pain (n = 78)

Symptoms

0.572; missing = 1

0.622; missing = 5

Pain

0.943; missing = 0

0.873; missing = 6

ADL

0.856; missing = 0

0.948; missing = 7

Sports

0.898; missing = 0

0.906; missing = 11

Quality of life

0.547; missing = 0

0.739; missing = 2

Total score

0.953; missing = 1

0.959; missing = 19

 

 

Construct Validity

Convergent validity:

Children with Knee Pathology: (Moutzouri et al, 2021; Greek translation of KOOS-Child)

  • Poor to Excellent convergent validity between KOOS-Child and KIDSCREEN subscales

Correlations between KOOS-Child and KIDSCREEN subscales

 

KIDSCREEN Subscales

KOOS-Child Subscales

Physical activities/health

General Feeling

Parents/Free Time

Friends

School

Pain

0.6

0.5

-

-

0.4

Symptoms

0.7

0.3

-

-

0.5

ADL

0.5

0.4

0.4

0.3

0.3

Sport-play

0.5

0.4

-

0.4

0.3

QoL

0.5

0.6

0.5

0.4

0.4

Note: p < 0.01 for all correlations

 

  • Poor to Excellent convergent validity between KOOS-Child and Kid-KINDL subscales

Correlations between KOOS-Child and Kid-KINDL subscales

 

Kid-KINDL Subscales

KOOS-Child Subscales

Physical Health

General Feeling

Self

Family

Friends

School

Hospital/Disease

Pain

0.5

0.5

-

-

-

-

0.3 (ns)

Symptoms

0.6

0.5

-

-

-

-

0.4*

ADL

0.6

0.5

-

-

-

-

-

Sport-play

0.6

0.4

-0.6 (ns)

-

-

-

-

QoL

0.6

0.6

0.1 (ns)

0.2 (ns)

0.6*

0.3

0.3 (ns)

Note: All correlations significant at p < 0.01 except where noted: ns = not significant (p>0.05) and * = significant at p < 0.05

 

Children with Stable Knee Conditions: (Van der Velden, 2019)

Adequate to Excellent convergent validity between KOOS-Child and other scales

 

KOOS Symptoms

KOOS Pain

KOOS ADL

KOOS Sport/play

KOOS QoL

Pedi-IKDC

0.69

0.84

0.83

0.80

0.76

Lysholm

0.70

0.71

0.66

0.56

0.57

NRS Pain

-0.44

-0.71

-0.62

-0.54

-0.52

EQ_5D

0.42

0.52

0.50

0.45

0.53

 

 

Patients with Knee Pain: (Rioux Trottier et al, 2018; French translation of KOOS-Child)

  • Poor correlation between KOOS-Child subscales and CHAQ grip subscales (pain = -0.023; symptom = 0.110; ADL = -0.102; sport/play = -0.091; QoL = 0.132)
  • Excellent correlation between KOOS-Child pain subscale and CHAQ pain subscale (-0.792)
  • Excellent correlation between KOOS-Child sport/play subscale and CHAQ run and play subscale (-0.809)
  • Excellent correlation between KOOS-Child ADL subscale and CHAQ walking subscale (-0.782)
  • Adequate correlation between KOOS-Child symptoms subscale and VAS (-0.507)
  • Excellent correlation between KOOS-Child pain, ADL, sport/play and QoL subscales and VAS (pain = -0.601; ADL = -0.646; sport/play = -0.604; QoL = -0.622)
  • Excellent correlation between KOOS-Child QoL subscale and EQ-5D-Y usual activities subscale (-0.788)

Content Validity

Children with Stable Knee Conditions: (Van der Velden, 2019)

Number of orthopedic surgeons and patients rating KOOS-Child subscales as relevant

Relevant items/total items (%)

Orthopedic surgeons

(n = 18)

Patients

(n = 18)

Symptoms

6/7 (86%)

7/7(100%)

Pain

7/8 (88%)

7/8 (88%)

ADL

7/11(64%)

9/11(82%)

Sport/play

7/7(100%)

7/7(100%)

QOL

5/6(83%)

6/6(100%)

 

“The KOOS-Child subscales were all found relevant by patients (all > 75%). The orthopedic surgeons rated the KOOS-Child subscales as relevant (all > 75%), except for the KOOS-Child ADL subscale (64%) (Van der Velden, et al., 2019, p. 4-5).”

 

Floor/Ceiling Effects

Patients with Knee Pain: (Rioux Trottier et al, 2018; French translation of KOOS-Child)

  • Excellent: no floor effects for KOOS-Child scales: Symptoms, Pain, and QoL
  • Adequate: floor effects of < 20% for ADL (1%) and Sport/Play (7.7%) scales
  • Adequate: ceiling effects of < 20% for KOOS-Child scales: Symptoms (13.4%), Pain (18.6%), and QoL (10.1%)
  • Poor: ceiling effects > 20% for ADL (21.2%) and Sport/Play (20.9%) scales

 

Children with Stable Knee Conditions: (Van der Velden, 2019)

  • Poor: ceiling effects were found for the KOOS-Child ADL, with 25% of the patients having the maximum score of > 95 (n = 53).
  • Adequate: ceiling effects of < 20% were found for the other KOOS-Child scales (n = 53): Symptoms (5%), Pain (5%), Sport/Play (2%), and QoL (1%)
  • Excellent: no floor effects found for KOOS-Child Symptoms, Pain, or ADL subscales
  • Adequate: floor effects of <20% for Sport/Play (18%) and QoL (1%) subscales 

 

Children with Knee Pathology: (Moutzouri et al, 2021; Greek translation of KOOS-Child)

  • Excellent: no floor effects for Symptoms, Pain, ADL, Sport/Play, or QoL subscales
  • Adequate: ceiling effects of < 25% for Pain (22.0%), Sport/Play (15.1%) and QoL (15.1%) subscales
  • Poor: ceiling effects of > 25% for Symptoms (27.4%) and ADL (39.8%) subscales

Responsiveness

Children with Knee Pathology: (Moutzouri et al, 2021; Greek translation of KOOS-Child)

  • Moderate effect size for pain, symptom, and QoL subscales at 2 weeks
  • Small effect size at 2 weeks for ADL and sport/play subscales

 

Moderate to Large Effect Sizes for KOOS-Child Subscales from Baseline to 3 Months

KOOS-Child Subscale

Effect Sizes (baseline to 3 months)

Pain

1.1

Symptoms

0.6

ADL

0.8

Sport/play

1.2

QoL

1.4

 

Children with Stable Knee Conditions: (Van der Velden et al., 2019)

Responsiveness of the KOOS-Child subscales (n =71)

Effect Size

Symptoms

Pain

ADL

Sport/Play

QoL

No Change (n =22)

0.29

0.27

0.13

0.28

-0.07

Improvement (n =42)

0.84

1.26

0.83

1.57

1.24

Worsening (n = 7)

-0.44

-0.43

-0.75

-1.23

-0.83

Bibliography

Baldwin, J. N., McKay, M. J., et al. (2017). Self-reported knee pain and disability among healthy individuals: Reference data and factors associated with the knee injury and osteoarthritis outcome score (KOOS) and KOOS-child. Osteoarthritis and Cartilage, 25(8), 1282-1290. 10.1016/j.joca.2017.03.007

Moutzouri, M., Tsoumpos, P., et al. (2021). “Greek KOOS-child: A valid, disease specific, diagnostically accurate and responsive PROM in children with knee-related pathology”. Knee Surgery, Sports Traumatology, Arthroscopy, 29(6), 1841-1849. 10.1007/s00167-020-06237-5

?rtqvist, M., Iversen, M. D., et al. (2014). Psychometric properties of the knee injury and osteoarthritis outcome score for children (KOOS-child) in children with knee disorders. British Journal of Sports Medicine, 48(19), 1437-1446. 10.1136/bjsports-2013-093164

Rioux Trottier, E., Beauséjour, M., et al. (2018). Validation of the French version of the KOOS-child questionnaire. Knee Surgery, Sports Traumatology, Arthroscopy : Official Journal of the ESSKA, 27(7), 2361-2367. 10.1007/s00167-018-5302-y

Van der Velden, C. A., van der Steen, M. C., et al. (2019). Pedi-IKDC or KOOS-child: Which questionnaire should be used in children with knee disorders? BMC Musculoskeletal Disorders, 20(1)

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