Abstract
Purpose
The aim of the study was to investigate the relationship between pain, function and quality of life with radiographic findings in patients with knee osteoarthritis (OA).
Methods
A total of 86 patients diagnosed with knee OA were included in the study. Demographic, physical, and pathological information was collected. Visual analog scale (VAS) was used to determine pain levels. The evaluation of radiographic findings was conducted by Kellgren-Lawrence (K&L) rating scale. The Turkish version of the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) questionnaire was used to evaluate the patient’s disability and functional status. The objective functional status was assessed using the commonly used physical performance test, the Timed up and Go Test (TUG). The Turkish version of the Short Form 36 (SF-36) questionnaire was used for quality of life assessment. The “Spearman rank correlation coefficient” was used to investigate the relationship between pain, function and quality of life with radiographic findings.
Results
The mean age of the participants was 61.08 ± 9.27 years. There was a strong correlation between VAS at activity and K&L (p < 0.05). There was a negative correlation between Physical Function (PF) (p < 0.05) and General Health (GH) (p < 0.05) subscore of the SF-36 with K&L. In addition, K&L and TUG were positively correlated (p < 0.05).
Conclusion
Radiographic findings were associated with pain in activity and functional status based on physical performance, but not with clinical results based on Patient Reported Outcome Measures (PROMs). As the patient’s radiographic findings worsened, the level of pain increased and functionality decreased.
Keywords: Knee, Osteoarthritis, Pain, Quality of life, Radiography
1. Introduction
Knee osteoarthritis (OA) is a degenerative joint disease characterized by functional impairment, pain and decreased quality of life.1 It is the most common joint disease in elderly individuals, affecting approximately 10% of the population over 60 years of age, and is particularly prevalent in women.2,3 With the increasing prevalence of aging and obesity, the number of individuals affected by OA is expected to reach 50% of the population within the next 20 years.4
The intraarticular and extraarticular structures are affected in knee OA. Joint cartilage, subchondral bone, ligaments, muscles around the joints, nerves, and synovial membrane are histopathologically changed.5 Along with all these emerging physiological signs, some frequent symptoms occur in patients. Clinically, it is known that functional loss, decrease in quality of life, pain, decreased range of motion, inadequacy in daily living activities are frequently seen in knee OA.6, 7, 8 In the evaluation of these clinical conditions in patients, both objective and subjective assessment methods and radiographic evaluations are performed, and different scores and ratings are used to determine the severity of the disease.9, 10, 11
In the staging of knee OA according to radiological status, radiographic knee OA classification systems such as Kellgren and Lawrence (K&L), Knee Society Radiographic Scoring System, and Ahlbäck radiographic classification focus on grading the severity of osteoarthritis by focusing on structural changes within the joint.12, 13, 14, 15 Besides, the results of radiographic evaluation results and clinical outcomes, especially in the final stage of knee OA, is essential to determine which results may be more critical when making a surgical decision.16,17 In the study conducted with knee OA cases, it was reported that almost 30% of the patients had rapid clinical and radiographic disease progression and symptom deterioration for the previous two years before TKA.18
Studies have been conducted in which different clinical and radiographic features of knee OA patients were compared, and their relationship was demonstrated at different levels of evidence. Parsons and collogues reported that the clinical symptoms was related with the severity of radiographic knee OA. However, the radiographic results of the tibiofemoral joint were more strongly correlated than the results of the patellofemoral joint in terms of specific clinical findings.19 In a similar cohort study, a moderate correlation was found between radiographic and clinical results of knee OA diagnosis.20 In another cohort, knee pain was strongly associated with a decrease in the joint cavity obtained from radiographic results, especially in men, while knee pain was reported in women without radiographic OA findings.21 In a 3-year prospective study that examined the relationship between clinical and radiographic findings in patients with knee osteoarthritis, the symptoms of knee OA patients were reported to be associated with narrowing of the joint cavity, but not with the presence of osteophytes protrusion.22 Cubukcu et al. reported that pain and stiffness affect the functional status and that clinical findings should be focused instead of radiographic evaluations.11
Both clinical and radiographic evaluation results are important for shaping the rehabilitation process in clinical decision making and patient follow-up. However, there is no definite consensus about the relationship between clinical and radiographic results and how they should be interpreted in the clinical decision-making process. The aim of this study was to investigate the relationship between pain, function and quality of life with radiographic findings in patients with knee osteoarthritis.
2. Methods
2.1. Study design and participants
A single-center prospective cross-sectional study was carried out with 86 patients diagnosed with knee OA according to ACR by an orthopaedic surgeon in the Orthopedics and Traumatology Clinic of “X” Hospital from 2016 to 2019. Inclusion criteria were; the diagnosis of knee OA and was to be Turkish literate. Elimination criteria; Intra-articular injection history in the last six months, history of knee trauma or surgery, inflammatory arthritis, history of metabolic bone disease, history of neoplasm, presence of other arthropathies. In the beginning, 108 patients were included in the study voluntarily, and 22 patients were excluded from the study. The data selection algorithm of the study was given in Fig. 1. The study protocol was approved by the ethics committee of “X” University. All assessments were made in accordance with the Helsinki Declaration. Written informed consent was obtained from all cases.
Fig. 1.
The data selection algorithm.
2.2. Sample size estimation
In order to reduce type 2 errors, sample size was determined by performing power analysis before data collection period. The required sample size was calculated using the G∗power 3.1 program based on an effect size of dz = 0.3, an error probability of 0.05, and statistical power of 0.80.23 Effect size was determined based upon a medium effect of 0.3, reported by similar studies.11,24 The sample should have been composed at least of 82 patients.
2.3. Data collection
The cases were evaluated on the same day of inclusion. Demographic, physical, and pathological information was collected. Visual analog scale (VAS) was used to determine pain levels. VAS is a simple, valid, and reliable scale. In order to determine the body pain, patients were asked to mark the severity of the pain on a 10 cm scale showing the numbers “0 (no pain)” and “10 (most severe pain)”. VAS was questioned both at rest and in activity, and the patient was asked to express “the most severe pain”.25
Antero-posterior and lateral sided radiographic images were recorded while the patient in standing. The evaluation of radiographic findings was conducted by Kellgren-Lawrence (K&L) staging by an experienced radiologist blinded to the patient’s clinical condition. The K&L rating scale is a widely used radiographic grading system, which is preferred in studies on knee OA, and also it has been accepted by the World Health Organization (WHO).26, 27, 28 In this system, the patient is classified between 0 and 4, with the increased severity of OA from the radiographic image. Grade 0 indicates the absence of OA and Grade 4 indicates severe OA.29 The cases were scored according to the worst knee degree in K&L for bilateral knee OA patients.
The Turkish version of the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) questionnaire was used to evaluate the patient’s disability and functional status. This questionnaire is a valid, reliable and highly sensitive index that clinically determines the change in health status of patients with osteoarthritis of the knee and hip OA.30
The objective functional status was assessed using the commonly used physical performance test, the Timed up and Go Test (TUG). In this test, the patients were asked to get up from the chair with the command starting from the sitting position and to walk as fast as they could to reach the predetermined distance of 3 m and to return to their seats.31 TUG was carried out three times. The time until they got out of the chair and sat down again was recorded. The Turkish version of the Short Form 36 (SF-36) questionnaire was used for quality of life assessment. SF 36 is a self-rating scale which consists of thirty-six items. These allow the measurement of eight dimensions of quality of life.32
2.4. Statistical analysis
All data analysis was performed with “The Statistical Product and Service Solutions version 25 (SPSS Inc, Chicago, IL)” computer program. Quantitative variables were presented as mean ± standard deviation (X ± SD), range (minimum-maximum) and qualitative variables percent (%). Results were considered statistically significant when p value < 0.05. The “Spearman rank correlation coefficient” was used to investigate the relationship between pain, function and quality of life with radiographic findings.
3. Results
A total of 86 patients (75 women (87.2%), 11 men (12.8%)) with a mean age of 61.08 ± 9.27 years (range, 38–81 years) were included in the study. The demographic, physical, and pathological characteristics of the patients are given in Table 1. The number of patients diagnosed with bilateral knee OA was 32 (37.2%). 77.9% of the patients had the habit of sitting by bending their knees. In 45.3% of the patients, morning stiffness lasted more than 15 min, 15.1% of the patients stated that they were not able to walk more than 200 m. 25.6% of the patients are at stage 4 according to the K&L. Radiographic image samples and their K&L scores are provided in Fig. 2, Fig. 3.
Table 1.
Demographic, physical and pathological characteristics of the patients.
| Total (n = 86) | |
|---|---|
| Age (years, mean ± SD) | 61.08 ± 9.27 |
| Height (m, mean ± SD) | 1.61 ± 0.06 |
| Weight (kg, mean ± SD) | 77.65 ± 16.08 |
| BMI (kg/cm2, mean ± SD) | 29.92 ± 6.23 |
| Affected knee | |
| Right (n, %) | 37 (43) |
| Left (n, %) | 17 (19.8) |
| Both (n, %) | 12 (37.2) |
| Residence | |
| Urban (n, %) | 47 (54.7) |
| Rural (n, %) | 39 (45.3) |
| K&L | |
| Stage 1 (n, %) | 8 (9.3) |
| Stage 2 (n, %) | 28 (32.6) |
| Stage 3 (n, %) | 28 (32.6) |
| Stage 4 (n, %) | 22 (25.6) |
SD: standard deviation, n: number of patients, %: percentage, K&L: The Kellgren-Lawrence Rating Scale.
Fig. 2.
Radiographic image samples (Grade 1 on the left, grade 2 on the right).
Fig. 3.
Radiographic image samples (Grade 3 on the left, grade 4 on the right).
The results of VAS, TUG WOMAC and SF-36 are given in Table 2. The relationship between the K&L with WOMAC, VAS, SF-36 and TUG are given in Table 3. There was a strong correlation between VAS at activity and K&L (p < 0.05, Table 3). There was a negative correlation between Physical Function (PF) and General Health (GH) subscore of the SF-36 with K&L (p < 0.05, Table 3). In addition, K&L and TUG were positively correlated (p < 0.05, Table 3).
Table 2.
Average values (standard deviation, min-max) for VAS, WOMAC and SF-36.
| n:86 | Mean ± SD | Range | |
|---|---|---|---|
| VAS | |||
| At rest | 8.40 ± 2.16 | (0–8.4) | |
| At activity | 4.78 ± 1.93 | (0.8–9.2) | |
| TUG | 11.39 ± 2.45 | (6.6–20.0) | |
| WOMAC | |||
| Pain | 9.09 ± 2.45 | (5–15) | |
| Stiffness | 2.40 ± 1.61 | (0–6) | |
| Physical Functions | 37.73 ± 9.29 | (20–58) | |
| Total | 49.23 ± 11.71 | (25–75) | |
| SF-36 | |||
| Physical function (PF) | 30.58 ± 27.46 | (0–100) | |
| Role limitations due to physical health (RP) | 22.09 ± 35.55 | (0–100) | |
| Bodily pain (BP) | 38.43 ± 15.72 | (0–77.5) | |
| General health (GH) | 45.53 ± 12.07 | (20–80) | |
| Energy/Vitality (VT) | 52.67 ± 8.49 | (35–85) | |
| Social function (SF) | 56.27 ± 16.59 | (25–87.5) | |
| Role limitations due to emotional problems (RH) | 69.76 ± 45.33 | (0–100) | |
| Emotional well-being (MH) | 53.22 ± 7.09 | (40–80) | |
SD: standard deviation, n: number of patients, VAS: Visual Analog Scale, WOMAC (Western Ontario and McMaster Universities Osteoarthritis Index), SF-36: Short Form 36 (SF-36), TUG: Timed up and Go Test.
Table 3.
Correlation between K&L with VAS, WOMAC, SF-36 and TUG.
| n:86 | K&L | |
|---|---|---|
| VAS | ||
| At rest | 0.164 | |
| At activity | 0.333∗∗ | |
| WOMAC | ||
| Pain | 0.045 | |
| Stiffness | 0.088 | |
| Physical Functions | 0.042 | |
| Total | 0.040 | |
| SF-36 | ||
| Physical function (PF) | −0.222∗ | |
| Role limitations due to physical health (RP) | −0.117 | |
| Bodily pain (BP) | −0.151 | |
| General health (GH) | −0.260∗ | |
| Energy/Vitality (VT) | 0.070 | |
| Social function (SF) | −0.171 | |
| Role limitations due to emotional problems (RH) | −0.129 | |
| Emotional well-being (MH) | −0.066 | |
| TUG | 0.236∗ | |
∗: p < 0.05, ∗∗: p < 0.01, K&L: The Kellgren-Lawrence Rating Scale, VAS: Visual Analog Scale, WOMAC (Western Ontario and McMaster Universities Osteoarthritis Index), SF-36: Short Form 36 (SF-36), TUG: Timed up and Go Test.
4. Discussion
The present study showed that radiographic findings of knee OA patients were associated with functional status based on the performance test “TUG” and pain at the activity. Radiographic status was not related to WOMAC, which is a reliable and valid questionnaire frequently used in the clinical evaluation of knee OA patients. Also, the severity of radiographic symptoms was related to only two subscores (PF and GH) of the SF-36 questionnaire which evaluates the quality of life of the patient. The results of our research are correlative to many other studies carried out for a similar purpose.
As stated in a comprehensive systematic review, there was no relationship between radiographic and clinical findings. It was stated that the results of the knee x-ray should not be used alone in patients with knee OA, because the results could vary depending on the x-ray image angle, the definition of pain and demographic factors.33 Nevertheless, according to the results obtained from many studies, there is a significant correlation between radiographic findings and clinical findings, especially for some parameters and conditions.
According to the results we obtained, the severity of radiological disease was not associated with resting pain, while it was associated with activity pain. In a study examining the relationship between radiographic findings and pain in detail, it was stated that radiographic findings with narrowing of the joint space, especially in men, are strongly associated with pain and women tend to have knee pain even without radiographic findings.21 Another study in which two separate cohort study results are given stated that pain and radiographic findings were related.34 Szebenyi and colleagues emphasized that the strongest relationship with pain was subchondral bone sclerosis in radiographic findings, and it was emphasized that the isolated examination of the patellar component was essential in order to make the results clearer.35
Another important result we have obtained was the increase in TUG time with the increase in the severity of the radiographic disease. In other words, as the radiographic stage of the patient increases, it is seen that the functional status based on physical performance decreases. One of the most important features that make our work unique is the assessment of functionality with both Patient Reported Outcome Measures (PROMs) and objective performance tests. TUG or other performance tests are not used in studies examining the relationship between radiographic findings and clinical findings in patients with knee OA.
No relationship was found between the radiographic findings and the PROMs. Only the SF-36’s two subscore (PF, GH) was found to be related. Cubukcu et al. and Mahran et al. obtained similar results with our study, showing that no sub-score of WOMAC was associated with radiographic findings.11,24 However, some studies have also indicated that WOMAC scores are related to radiographic findings.18,36 Another point emphasized in the studies is that while looking at this relationship, the tibiofemoral and patellofemoral components of the knee should be evaluated separately.19,35 Studies also have shown that quality of life (SF-36) and radiographic findings are related and not related.37,38
It should not be overlooked that our study has limitations. A significant limitation, which we have observed in the literature, is PROMs. Although WOMAC is a valid and reliable questionnaire, scoring is performed only by clinical symptom assessment.39 Using PROMs such as "The New Knee Society Scoring System", which includes the radiographic score and objective assessment, could provide more efficient results.40 Besides, one of the most emphasized issues in the literature is that the knee joint should be evaluated as components. The fact that it was not included in the statistical analysis of the findings such as osteophyte and subchondral sclerosis obtained from radiographic images, our finding with only K&L could be considered as an important limitation to provide information in terms of characteristic radiographic findings.
5. Conclusion
Radiographic findings were associated with pain in activity and functional status based on physical performance, but not with clinical results based on PROMs. As the patient’s radiographic findings worsened, the level of pain increased and functionality decreased. Only two parameters of quality of life were found to be related, but the remaining 6 parameters was not related to. Also, there were no relationship between radiographic status and any subscore of knee specific survey results. Conducting the study with a knee-specific questionnaire including radiographic evaluation score and handling the knee joint to separate components and also in terms of radiographic symptom indications will be important for making the results comprehensive.
Funding
This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.
Declaration of competing interest
None.
Acknowledgements
None.
Contributor Information
Fatih Özden, Email: fatihozden@mu.edu.tr.
Özgür Nadiye Karaman, Email: ozgurnadiye@gmail.com.
Nazan Tuğay, Email: ntugay@mu.edu.tr.
Cem Yalın Kilinç, Email: cykilinc@mu.edu.tr.
Rabia Mihriban Kilinç, Email: rabiakilinc@mu.edu.tr.
Baki Umut Tuğay, Email: umutt@mu.edu.tr.
References
- 1.Jones L.D., Bottomley N., Harris K., Jackson W., Price A.J., Beard D.J. The clinical symptom profile of early radiographic knee arthritis: a pain and function comparison with advanced disease. Knee Surg Sports Traumatol Arthrosc. 2016;24:161–168. doi: 10.1007/s00167-014-3356-z. [DOI] [PubMed] [Google Scholar]
- 2.Herman A., Chechik O., Segal G. The correlation between radiographic knee OA and clinical symptoms—do we know everything? Clin Rheumatol. 2015;34:1955–1960. doi: 10.1007/s10067-015-2871-8. [DOI] [PubMed] [Google Scholar]
- 3.Fibel K.H., Hillstrom H.J., Halpern B.C. State-of-the-Art management of knee osteoarthritis. World J. Clin. Case: WJCC. 2015;3:89. doi: 10.12998/wjcc.v3.i2.89. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 4.Hunter D.J., Schofield D., Callander E. The individual and socioeconomic impact of osteoarthritis. Nat Rev Rheumatol. 2014;10:437. doi: 10.1038/nrrheum.2014.44. [DOI] [PubMed] [Google Scholar]
- 5.Ertürk C., Altay M.A., Altay N., Kalender A.M., Öztürk İ.A. Will a single periarticular lidocaine–corticosteroid injection improve the clinical efficacy of intraarticular hyaluronic acid treatment of symptomatic knee osteoarthritis? Knee Surg Sports Traumatol Arthrosc. 2016;24:3653–3660. doi: 10.1007/s00167-014-3398-2. [DOI] [PubMed] [Google Scholar]
- 6.Øiestad B.E., White D.K., Booton R. Longitudinal course of physical function in people with symptomatic knee osteoarthritis: data from the multicenter osteoarthritis study and the osteoarthritis initiative. Arthritis Care Res. 2016;68:325–331. doi: 10.1002/acr.22674. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 7.Fukutani N., Iijima H., Aoyama T. Knee pain during activities of daily living and its relationship with physical activity in patients with early and severe knee osteoarthritis. Clin Rheumatol. 2016;35:2307–2316. doi: 10.1007/s10067-016-3251-8. [DOI] [PubMed] [Google Scholar]
- 8.Kiadaliri A.A., Lamm C.J., de Verdier M.G. Association of knee pain and different definitions of knee osteoarthritis with health-related quality of life: a population-based cohort study in southern Sweden. Health Qual Life Outcome. 2016;14:121. doi: 10.1186/s12955-016-0525-4. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 9.Collins N.J., Misra D., Felson D.T., Crossley K.M., Roos E.M. Measures of knee function: international knee documentation committee (IKDC) subjective knee evaluation Form, knee injury and osteoarthritis outcome score (KOOS), knee injury and osteoarthritis outcome score physical function Short Form (KOOS-PS), knee outcome survey activities of daily living scale (KOS-adl), lysholm knee scoring scale, oxford knee score (OKS), western Ontario and McMaster Universities osteoarthritis index (WOMAC), activity rating scale (ARS), and tegner activity score (TAS) Arthritis Care Res. 2011;63:S208–S228. doi: 10.1002/acr.20632. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 10.Lo G.H., McAlindon T.E., Hawker G.A. Symptom assessment in knee osteoarthritis needs to account for physical activity level. Arthritis Rheumatol. 2015;67:2897–2904. doi: 10.1002/art.39271. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 11.Cubukcu D., Sarsan A., Alkan H. Relationships between pain, function and radiographic findings in osteoarthritis of the knee: a cross-sectional study. Arthritis. 2012;2012 doi: 10.1155/2012/984060. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 12.Petersson I.F., Boegård T., Saxne T., Silman A.J., Svensson B. Radiographic osteoarthritis of the knee classified by the Ahlbäck and Kellgren & Lawrence systems for the tibiofemoral joint in people aged 35–54 years with chronic knee pain. Ann. Rheum. Dis. 1997;56:493–496. doi: 10.1136/ard.56.8.493. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 13.National C.G.C.U.K. 2014. Osteoarthritis: Care and Management in Adults. [PubMed] [Google Scholar]
- 14.Zhang W., Ma Doherty, Peat G. EULAR evidence-based recommendations for the diagnosis of knee osteoarthritis. Ann. Rheum. Dis. 2010;69:483–489. doi: 10.1136/ard.2009.113100. [DOI] [PubMed] [Google Scholar]
- 15.Altman R., Asch E., Bloch D. Development of criteria for the classification and reporting of osteoarthritis: classification of osteoarthritis of the knee. Arthritis Rheum: Off. J. Am. Coll. Rheumatol. 1986;29:1039–1049. doi: 10.1002/art.1780290816. [DOI] [PubMed] [Google Scholar]
- 16.Gademan M.G.J., Hofstede S.N., Vlieland T.P.M.V., Nelissen R.G.H.H., Marang-van de Mheen P.J. Indication criteria for total hip or knee arthroplasty in osteoarthritis: a state-of-the-science overview. BMC Muscoskel Disord. 2016;17:463. doi: 10.1186/s12891-016-1325-z. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 17.Hamel M.B., Toth M., Legedza A., Rosen M.P. Joint replacement surgery in elderly patients with severe osteoarthritis of the hip or knee: decision making, postoperative recovery, and clinical outcomes. Arch Intern Med. 2008;168:1430–1440. doi: 10.1001/archinte.168.13.1430. [DOI] [PubMed] [Google Scholar]
- 18.Riddle D.L., Jiranek W.A. Knee osteoarthritis radiographic progression and associations with pain and function prior to knee arthroplasty: a multicenter comparative cohort study. Osteoarthritis Cartilage. 2015;23:391–396. doi: 10.1016/j.joca.2014.12.013. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 19.Parsons C., Fuggle N.R., Edwards M.H. Concordance between clinical and radiographic evaluations of knee osteoarthritis. Aging Clin Exp Res. 2018;30:17–25. doi: 10.1007/s40520-017-0847-z. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 20.Parsons C., Clynes M., Syddall H. How well do radiographic, clinical and self-reported diagnoses of knee osteoarthritis agree? Findings from the Hertfordshire cohort study. SpringerPlus. 2015;4:177. doi: 10.1186/s40064-015-0949-z. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 21.Muraki S., Oka H., Akune T. Prevalence of radiographic knee osteoarthritis and its association with knee pain in the elderly of Japanese population-based cohorts: the ROAD study. Osteoarthritis Cartilage. 2009;17:1137–1143. doi: 10.1016/j.joca.2009.04.005. [DOI] [PubMed] [Google Scholar]
- 22.Fukui N., Yamane S., Ishida S. Relationship between radiographic changes and symptoms or physical examination findings in subjects with symptomatic medial knee osteoarthritis: a three-year prospective study. BMC Muscoskel Disord. 2010;11:269. doi: 10.1186/1471-2474-11-269. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 23.Faul F, Erdfelder E, Lang A-G, Buchner A. G∗ Power 3: A Flexible Statistical Power Analysis Program for the Social [DOI] [PubMed]
- 24.Mahran S.A., Elias A.Y., Janbi F.S., El-Deek B.S. Relationship between clinical and radiographic findings in osteoarthritis knee: a cross-sectional study. J King Abdulaziz Univ Med Sci. 2015;22:1–9. [Google Scholar]
- 25.Bijur P.E., Silver W., Gallagher E.J. Reliability of the visual analog scale for measurement of acute pain. Acad Emerg Med. 2001;8:1153–1157. doi: 10.1111/j.1553-2712.2001.tb01132.x. [DOI] [PubMed] [Google Scholar]
- 26.Holzer N., Salvo D., Marijnissen A.C.A. Radiographic evaluation of posttraumatic osteoarthritis of the ankle: the Kellgren–Lawrence scale is reliable and correlates with clinical symptoms. Osteoarthritis Cartilage. 2015;23:363–369. doi: 10.1016/j.joca.2014.11.010. [DOI] [PubMed] [Google Scholar]
- 27.Park H.-J., Kim S.S., Lee S.-Y. A practical MRI grading system for osteoarthritis of the knee: association with Kellgren–Lawrence radiographic scores. Eur J Radiol. 2013;82:112–117. doi: 10.1016/j.ejrad.2012.02.023. [DOI] [PubMed] [Google Scholar]
- 28.Kellgren J.H., Lawrence J.S. Radiological assessment of osteo-arthrosis. Ann. Rheum. Dis. 1957;16:494. doi: 10.1136/ard.16.4.494. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 29.Kohn M.D., Sassoon A.A., Fernando N.D. Springer; 2016. Classifications in Brief: Kellgren-Lawrence Classification of Osteoarthritis. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 30.Tüzün E.H., Eker L., Aytar A., Daşkapan A., Bayramoğlu M. Acceptability, reliability, validity and responsiveness of the Turkish version of WOMAC osteoarthritis index. Osteoarthritis Cartilage. 2005;13:28–33. doi: 10.1016/j.joca.2004.10.010. [DOI] [PubMed] [Google Scholar]
- 31.Alghadir A., Anwer S., Brismée J.-M. The reliability and minimal detectable change of Timed up and Go test in individuals with grade 1–3 knee osteoarthritis. BMC Muscoskel Disord. 2015;16:174. doi: 10.1186/s12891-015-0637-8. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 32.Koçyiğit H., Aydemir Ö., Fişek G., Ölmez N., Memiş A.K. Form-36 (KF-36)’nın Türkçe versiyonunun güvenilirliği ve geçerliliği. Ilaç ve tedavi dergisi. 1999;12:102–106. [Google Scholar]
- 33.Bedson J., Croft P.R. The discordance between clinical and radiographic knee osteoarthritis: a systematic search and summary of the literature. BMC Muscoskel Disord. 2008;9:116. doi: 10.1186/1471-2474-9-116. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 34.Neogi T., Felson D., Niu J. Association between radiographic features of knee osteoarthritis and pain: results from two cohort studies. BMJ. 2009;339:b2844. doi: 10.1136/bmj.b2844. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 35.Szebenyi B., Hollander A.P., Dieppe P. Associations between pain, function, and radiographic features in osteoarthritis of the knee. Arthritis Rheum: Off. J. Am. Coll. Rheumatol. 2006;54:230–235. doi: 10.1002/art.21534. [DOI] [PubMed] [Google Scholar]
- 36.Duncan R., Peat G., Thomas E., Hay E., McCall I., Croft P. Symptoms and radiographic osteoarthritis: not as discordant as they are made out to be? Ann. Rheum. Dis. 2007;66:86–91. doi: 10.1136/ard.2006.052548. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 37.Pereira D., Severo M., Santos R.A. Knee and hip radiographic osteoarthritis features: differences on pain, function and quality of life. Clin Rheumatol. 2016;35:1555–1564. doi: 10.1007/s10067-015-3087-7. [DOI] [PubMed] [Google Scholar]
- 38.Salaffi F., Carotti M., Stancati A., Grassi W. Health-related quality of life in older adults with symptomatic hip and knee osteoarthritis: a comparison with matched healthy controls. Aging Clin Exp Res. 2005;17:255–263. doi: 10.1007/BF03324607. [DOI] [PubMed] [Google Scholar]
- 39.Salaffi F., Leardini G., Canesi B. Reliability and validity of the western Ontario and McMaster Universities (WOMAC) osteoarthritis index in Italian patients with osteoarthritis of the knee. Osteoarthritis Cartilage. 2003;11:551–560. doi: 10.1016/s1063-4584(03)00089-x. [DOI] [PubMed] [Google Scholar]
- 40.Özden F., Tuğay N., Tuğay B.U., Kılınç C.Y. Psychometrical properties of the Turkish translation of the new knee society scoring system. Acta Orthop Traumatol Turcica. 2019;53:184–188. doi: 10.1016/j.aott.2019.03.003. [DOI] [PMC free article] [PubMed] [Google Scholar]