Highlights
- •It is not clear if exercises improve knee biomechanics in osteoarthritis patients.
- •Exercises not patient-specific may improve outcomes but not biomechanical markers.
- •Targeted exercises from a knee kinesiography exam can improve markers and outcomes.
- •Patients with such approach are 2.5 times more likely to improve their markers.
Abstract
Background
Methods
Results
Conclusions
Keywords
1. Introduction
- Bennell K.L.
- Dobson F.
- Roos E.M.
- Skou S.T.
- Hodges P.
- Wrigley T.V.
- et al.
2. Materials and methods
2.1 Study design
2.2 Ethics
2.3 Procedure
2.4 Biomechanical markers
Biomechanical markers / Status | Absent | Moderate | Severe |
---|---|---|---|
Sagittal plane | |||
Knee flexion at heel strike 13 , 24 | Angle ≤ 10° at 1% GC | NA | >10° |
Knee extension at heel strike [25] | Angle ≥ 2° at 1% GC | NA | <2° |
Limited flexion excursion during loading 26 , 27 | Amplitude ≥ 14° at 1–20% GC | [8°; 14°] | <8° |
Fixed flexion during stance 26 , 27 | Amplitude ≥ 17° at 1–70% GC | [0°; 17°] | <0° |
Decrease of maximum flexion during swing 26 , 28 | Maximum ≥ 47° at 1–100% GC | NA | <47° |
Decrease of sagittal plane range of motion [26] | Amplitude ≥ 58° at 1–100% GC | [50°; 58°] | <50° |
Frontal plane | |||
Knee varus at heel strike [29] | Angle ≤ 2° at 1% GC | NA | >2° |
Knee valgus at heel strike [29] | Angle ≥ -2° at 1% G | NA | <-2° |
Varus thrust during loading 30 , 31 | Amplitude ≤ 2.5° at 1–20% GC | [2.5°; 7°] | >7° |
Valgus thrust during loading 30 , 31 | Amplitude ≥ −2.5° at 1–20% GC | [-7°; -2.5°] | <-7° |
Knee varus during stance 29 , 32 | Amplitude ≤ 2° at 20–54% GC | [2°; 5°] | >5° |
Knee valgus during stance 29 , 32 | Amplitude ≥ -2° at 20–54% GC | [-5°; -2°] | <-5° |
Transverse plane | |||
External tibia rotation at heel strike [33] | Angle ≤ 4.5° at 1% GC | [4.5°; 7.5°] | >7.5° |
Internal rotation of the tibia with regard to the femur during loading [33] | Amplitude ≥ 1° at 1–20% GC | NA | <-1° |
2.5 Targeted exercises
2.6 Sample size
2.7 Outcomes
2.7.1 Primary outcome
2.7.2 Secondary outcomes
2.8 Statistical analyses
Cut-off categorizations / GER levels | (a) Deteriorated | (b) Stabilized | (c) Improved |
---|---|---|---|
GER_Cat1 (Inclusive): Less or more improved than deteriorated BMs | GER < 1 | GER = 1 | GER > 1 |
GER_Cat2 (Reasonable): 2-times less or more improved than deteriorated BMs | GER ≤ 0.5 | 0.5 < GER < 2 | GER ≥ 2 |
GER_Cat3 (Restrictive): 3-times less or more improved than deteriorated BMs | GER ≤ 0.33 | 0.33 < GER < 3 | GER ≥ 3 |
- Bennell K.L.
- Dobson F.
- Roos E.M.
- Skou S.T.
- Hodges P.
- Wrigley T.V.
- et al.
3. Results
3.1 Participants’ characteristics

Group 1 (Control) n = 71 | Group 2 (Exercise) n = 33 | Group 3 (Exercise&Education) n = 59 | ANOVA or Chi-squared test | |
---|---|---|---|---|
Patients’ characteristics | Mean (95% CI) or n (%) | Mean (95% CI) or n (%) | Mean (95% CI) or n (%) | P |
Age | 62.3 (60.1;64.5) | 63.3 (61.1;65.5) | 63.3 (61.1;65.6) | 0.75 |
BMI | 29.5 (28.3;30.8) | 30.4 (28.5;32.2) | 29.6 (28.4;30.7) | 0.71 |
Sex (women) | 48 (67.6%) | 22 (66.7%) | 35 (59.3%) | 0.62 |
Severity KL grade | 0.71 | |||
Grade 2 | 25 (35.2%) | 9 (27.3%) | 15 (25.4%) | |
Grade 3 | 27 (38.0%) | 13 (39.4%) | 22 (37.3%) | |
Grade 4 | 19 (26.8%) | 11 (33.3%) | 22 (37.3%) | |
Biomechanical markers | ||||
Total number of BMs with ‘Moderate’or ‘Severe’ status | 5.3 (4.9;5.6) | 6.0 (5.6;6.4) | 6.0 (5.6; 6.4) | 0.02* |
Sagittal plane | Mean, ° (95% CI) | Mean, ° (95% CI) | Mean, ° (95% CI) | |
Flexion/extension angle at heel strike | 12.28 (10.78;13.77) | 11.24 (9.29;13.20) | 12.90 (11.26;14.54) | 0.50 |
Flexion excursion amplitude during loading | 5.95 (5.06;6.83) | 5.68 (4.36;7.01) | 6.71 (5.63;7.79) | 0.42 |
Flexion/extension amplitude during stance | 13.66 (12.21;15.10) | 11.57 (9.71;13.43) | 12.39 (10.73;14.06) | 0.25 |
Maximum flexion angle during swing | 59.80 (58.47;61.14) | 57.91 (55.46;60.36) | 60.29 (58.95;61.64) | 0.18 |
Sagittal plane range of motion | 55.40 (53.77;57.03) | 53.18 (50.33;56.04) | 53.38 (51.28;55.47) | 0.25 |
Frontal plane | ||||
Varus/valgus angle at heel strike | 4.65 (3.48;5.81) | 4.39 (2.70;6.07) | 4.33 (2.91;5.74) | 0.94 |
Varus thrust during loading | 1.52 (1.27;1.78) | 2.23 (1.66;2.80) | 1.91 (1.58;2.24) | 0.03* |
Valgus thrust during loading | 0.53 (0.34;0.72) | 0.34 (0.16;0.53) | 0.36 (0.22;0.50) | 0.27 |
Varus/valgus amplitude during stance | 3.74 (2.49;5.00) | 4.44 (2.51;6.37) | 4.03 (2.51;5.55) | 0.85 |
Transverse plane | ||||
External/internal tibia rotation angle at heel strike | 2.94 (2.14;3.74) | 2.42 (1.14;3.71) | 2.97 (2.06;3.88) | 0.75 |
External/internal rotation of the tibia in regards of the femur during loading | −0.17 (−0.78;0.45) | −0.01 (−1.15;1.14) | −0.15 (−0.92;0.62) | 0.97 |
3.2 Primary outcome
3.2.1 Descriptive statistics

3.2.2 Ordinal logistic regressions
Odds ratio | 95% CI | P | |
---|---|---|---|
GER_Cat1 (Inclusive) | |||
Age * | 1.02 | 0.99 ; 1.06 | 0.20 * |
BMI | 1.00 | 0.94 ; 1.06 | 0.96 |
KOOS pain * | (−) 0.99 | 0.97 ; 1.01 | 0.20 * |
Sex | 1.40 | 0.77 ; 2.53 | 0.29 |
KL grade | 1.21 | 0.85 ; 1.74 | 0.31 |
GER_Cat2 (Reasonable) | |||
Age * | 1.03 | 0.99 ; 1.06 | 0.14 * |
BMI | (−) 1.00 | 0.96 ; 1.06 | 0.99 |
KOOS pain * | (−) 0.99 | 0.97 ; 1.01 | 0.22 * |
Sex | 1.28 | 0.71 ; 2.30 | 0.44 |
KL grade | 1.20 | 0.83 ; 1.71 | 0.35 |
GER_Cat3 (Restrictive) | |||
Age | 1.02 | 0.98 ; 1.05 | 0.31 |
BMI | (−) 0.98 | 0.92 ; 1.04 | 0.49 |
KOOS pain | (−) 0.99 | 0.98 ; 1.01 | 0.55 |
Sex | 1.10 | 0.60 ; 2.03 | 0.76 |
KL grade * | 1.43 | 0.98 ; 2.08 | 0.08 * |
Odds ratio | 95% CI | P | |
---|---|---|---|
GER_Cat1 (Inclusive) | |||
Age | 1.02 | 0.99 ; 1.06 | 0.21 |
KOOS pain | (−) 0.99 | 0.97 ; 1.01 | 0.19 |
Group 1 (Control) (reference) | NA | NA | NA |
Group 2 (Exercise) | 1.86 | 0.85 ; 4.03 | 0.14 |
Group 3 (Exercise&Education) ** | 2.46 | 1.28 ; 4.74 | 0.01 ** |
GER_Cat2 (Reasonable) | |||
Age | 1.03 | 0.99 ; 1.06 | 0.14 |
KOOS pain | (−) 0.99 | 0.97 ; 1.01 | 0.19 |
Group 1 (Control) (reference) | NA | NA | NA |
Group 2 (Exercise) | 1.79 | 0.82 ; 3.88 | 0.16 |
Group 3 (Exercise&Education) ** | 2.51 | 1.30 ; 4.83 | 0.008 ** |
GER_Cat3 (Restrictive) | |||
KL Grade | 1.38 | 0.95 ; 2.02 | 0.11 |
Group 1 (Control) (reference) | NA | NA | NA |
Group 2 (Exercise) | 1.26 | 0.57 ; 2.77 | 0.59 |
Group 3 (Exercise&Education) | 1.64 | 0.84 ; 3.19 | 0.16 |
3.3 Secondary outcomes
Group 1 (Control) n = 71 | Group 2 (Exercise) n = 33 | Group 3 (Exercise&Education) N = 59 | Time*group interaction | Main effects time/group | |
---|---|---|---|---|---|
KOOS (6-month minus baseline) | Mean difference (95% CI) | Mean difference (95% CI) | Mean difference (95% CI) | P | P |
Symptoms | 1.9 (−1.5;5.2) | 7.6 (1.9;13.2) | 6.3 (3.6;9.0) | 0.08 | <0.001**/0.90 |
Pain | 1.4 (−2.2;5.0) | 7.5 (3.7;11.2) | 7.4 (4.2;10.7) | 0.03* | Post-hoc |
Activities of daily living | 0.5 (−3.0;3.9) | 6.5 (2.8;10.2) | 6.4 (2.7;10.1) | 0.03* | Post-hoc |
Sports and recreation | 6.1 (1.1;11.1) | 2.9 (−4.2;9.9) | 6.5 (1.5;11.6) | 0.70 | <0.001**/0.91 |
Quality of life | 4.2 (0.2;8.3) | 9.7 (2.5;16.8) | 10.8 (6.2;15.4) | 0.11 | 0.001**/0.39 |
Post-hoc: Time – simple main effect | Mean difference (P) | Mean difference (P) | Mean difference (P) | ||
Pain | 1.4 (P = 1.0) | 7.5 (P < 0.005)** | 7.4 (P < 0.001)** | ||
Activities of daily living | 0.5 (P = 1.0) | 6.5 (P = 0.01)* | 6.4 (P = 0.01)* |

4. Discussion
4.1 Significance of the results
- Kigozi J.
- Jowett S.
- Nicholls E.
- Tooth S.
- Hay E.M.
- Foster N.E.
- et al.
Chapple CM. Physiotherapy for Osteoarthritis of the Knee: Predictors of Outcome at One Year (Thesis, Doctor of Philosophy). University of Otago; 2012. Retrieved from http://hdl.handle.net/10523/2194.
4.2 Study limitations
5. Conclusions
Funding
Declaration of Competing Interest
Acknowledgments
Appendix A. Supplementary material
- Supplementary data 1
References
- OARSI guidelines for the non-surgical management of knee, hip, and polyarticular osteoarthritis.Osteoarthr Cartil. 2019; 27: 1578-1589
Royal Australian College of General Practitioners. Guidelines for the Management of Knee and Hip Osteoarthritis. 2nd ed. East Melbourne, Vic: RACGP; 2018. p.1–82.
- 2019 American College of Rheumatology/Arthritis Foundation Guideline for the Management of Osteoarthritis of the Hand, Hip, and Knee.Arthritis Rheumatol. 2020; 72: 220-233
- Exercise for osteoarthritis of the knee: A Cochrane systematic review.Br J Sports Med. 2015 Dec; 49: 1554-1557https://doi.org/10.1136/bjsports-2015-095424
- Pain and functional trajectories in symptomatic knee osteoarthritis over up to 12 weeks of exercise exposure.Osteoarthr Cartil. 2018; 26: 501-512
- Comparing the efficacy of aquatic exercises and land-based exercises for patients with knee osteoarthritis.J Clin Nurs. 2011; 20: 2609-2622https://doi.org/10.1111/j.1365-2702.2010.03675.x
- Efficacy of a biomechanically-based yoga exercise program in knee osteoarthritis: A randomized controlled trial.PLoS ONE. 2018 Apr 17; 13: e0195653https://doi.org/10.1371/journal.pone.0195653
- No effects of functional exercise therapy on walking biomechanics in patients with knee osteoarthritis: exploratory outcome analyses from a randomised trial.BMJ Open Sport Exerc Med. 2017 Mar 27; 2: e000230https://doi.org/10.1136/bmjsem-2017-000230
- Exercise alters gait pattern but not knee load in patients with knee osteoarthritis.Biomed Res Int. 2016; 2016: 1-12
- Effect of exercise and gait retraining on knee adduction moment in people with knee osteoarthritis.Proc Inst Mech Eng H. 2014 Feb; 228: 190-199https://doi.org/10.1177/0954411914521155
- Neuromuscular versus quadriceps strengthening exercise in patients with medial knee osteoarthritis and varus malalignment: A randomized controlled trial.Arthritis Rheumatol. 2014; 66: 950-959
- Varus thrust and incident and progressive knee osteoarthritis.Arthritis Rheumatol. 2017; 69: 2136-2143
- Applied biomechanics of the patella.Clin Orthop Relat Res. 2001 Aug; 389: 9-14https://doi.org/10.1097/00003086-200108000-00003
- Association of mechanical factors with medial knee osteoarthritis: A cross-sectional study from Matsudai Knee Osteoarthritis Survey.J Orthop Sci. 2016 Jul; 21: 463-468https://doi.org/10.1016/j.jos.2016.03.006
- OARSI-FDA initiative: defining the disease state of osteoarthritis.Osteoarthr Cartil. 2011; 19: 478-482
- Influence of biomechanical characteristics on pain and function outcomes from exercise in medial knee osteoarthritis and varus malalignment: Exploratory analyses from a randomized controlled trial.Arthritis Care Res (Hoboken). 2015; 67: 1281-1288
- Gait analysis of patients with knee osteoarthritis highlights a pathological mechanical pathway and provides a basis for therapeutic interventions.EFORT Open Rev. 2017 Mar 13; 1: 368-374https://doi.org/10.1302/2058-5241.1.000051
- A biomechanical perspective on physical therapy management of knee osteoarthritis.J Orthop Sports Phys Ther. 2013 Sep; 43: 600-619https://doi.org/10.2519/jospt.2013.4121
- Good Life with osteoArthritis in Denmark (GLA:D™): Evidence-based education and supervised neuromuscular exercise delivered by certified physiotherapists nationwide.BMC Musculoskelet Disord. 2017 Feb 7; 18: 72https://doi.org/10.1186/s12891-017-1439-y
- Effect of home exercise program in patients with knee osteoarthritis: A systematic review and meta-analysis.J Geriatr Phys Ther. 2016; 39: 38-48
- A multi-arm cluster randomized clinical trial of the use of knee kinesiography in the management of osteoarthritis patients in a primary care setting.Postgrad Med. 2020; 132: 91-101
- Radiological assessment of osteo-arthrosis.Ann Rheum Dis. 1957; 16: 494-502
- The KneeKG system: A review of the literature.Knee Surg Sports Traumatol Arthrosc. 2012 Apr; 20: 633-638https://doi.org/10.1007/s00167-011-1867-4
- Focusing osteoarthritis management on modifiable risk factors and future therapeutic prospects.Ther Adv Musculoskelet Dis. 2009; 1: 35-47https://doi.org/10.1177/1759720x09342132
- Secondary gait changes in patients with medial compartment knee osteoarthritis: increased load at the ankle, knee, and hip during walking.Arthritis Rheum. 2005; 52: 2835-2844
- Biomechanical changes at the hip, knee, and ankle joints during gait are associated with knee osteoarthritis severity.J Orthop Res. 2008; 26: 332-341
- Influences on knee movement strategies during walking in persons with medial knee osteoarthritis.Arthritis Rheum. 2007; 57: 1018-1026https://doi.org/10.1002/art.22889
- Kinetic and kinematic characteristics of gait in patients with medial knee arthrosis.Acta Orthop Scand. 2002; 73: 647-652https://doi.org/10.1080/000164702321039606
- Varus–valgus alignment: Reduced risk of subsequent cartilage loss in the less loaded compartment.Arthritis Rheum. 2011; 63: 1002-1009
Boivin K. Développement d'une approche d'évaluation clinique de la cinématique tridimensionnelle du genou durant la marche pour des patients gonarthrosiques. Ph.D. Thesis. École Polytechnique de Montréal, Montréal, Canada; 2010.
- A quantitative assessment of varus thrust in patients with medial knee osteoarthritis.Knee. 2012; 19: 130-134
- The role of knee alignment in disease progression and functional decline in knee osteoarthritis.JAMA. 2001; 286: 188-195
- Rotational changes at the knee after ACL injury cause cartilage thinning.Clin Orthop Relat Res. 2006; 442: 39-44
- The Knee injury and Osteoarthritis Outcome Score (KOOS): From joint injury to osteoarthritis.Health Qual Life Outcomes. 2003 Nov; 3: 64https://doi.org/10.1186/1477-7525-1-64
- A tutorial on sensitivity analyses in clinical trials: The what, why, when and how.BMC Med Res Method. 2013; 13: 92
Katz MH. Multivariable Analysis – A Practical Guide for Clinicians and Public Health Researchers. Third Edition. Cambridge University Press; 2011. doi: 10.1017/CBO9780511974175.
- Frontal plane biomechanics in males and females with and without patellofemoral pain.Med Sci Sports Exerc. 2012 Sep; 44: 1747-1755https://doi.org/10.1249/MSS.0b013e318256903a
- The relationship of self-reported pain and functional impairment to gait mechanics in overweight and obese persons with knee osteoarthritis.Arch Phys Med Rehabil. 2009; 90: 1874-1879
- Some aspects of the design and analysis of cluster randomization trials.J R Stat Soc: Ser C: Appl Stat. 1998; 47: 95-113
- Analysis of cluster randomized trials in primary care: a practical approach.Fam Pract. 2000; 17: 192-196https://doi.org/10.1093/fampra/17.2.192
- Cluster randomized trials in general (family) practice research.Stat Methods Med Res. 2000; 9: 81-94
- Is there an effective way to prescribe a home-based exercise program in patients with knee osteoarthritis? A randomized controlled study.Turkiye Fiziksel Tip ve Rehabilitasyon Dergisi. 2013; 59: 1-6https://doi.org/10.4274/tftr.70894
- A randomised controlled trial of a self-management education program for osteoarthritis of the knee delivered by health care professionals.Arthritis Res Ther. 2012 Jan 27; 14: R21https://doi.org/10.1186/ar3703
- Effects of a tailor-made exercise program on exercise adherence and health outcomes in patients with knee osteoarthritis: A mixed-methods pilot study.Clin Interv Aging. 2016 Oct; 5: 1391-1402https://doi.org/10.2147/CIA.S111002
- Cost-utility analysis of interventions to improve effectiveness of exercise therapy for adults with knee osteoarthritis: The BEEP trial.Rheumatol Adv Pract. 2018;2(2):rky018; https://doi.org/10.1093/rap/rky018
- Cost-effectiveness of nonpharmacologic, nonsurgical interventions for hip and/or knee osteoarthritis: systematic review.Value Health. 2012 Jan; 15: 1-12https://doi.org/10.1016/j.jval.2011.09.003
- Cost-effectiveness of 12 weeks of supervised treatment compared to written advice in patients with knee osteoarthritis: A secondary analysis of the 2-year outcome from a randomized trial.Osteoarthr Cartil. 2020 Jul; 28: 907-916https://doi.org/10.1016/j.joca.2020.03.009
- Do comorbidities predict pain and function in knee osteoarthritis following an exercise intervention, and do they moderate the effect of exercise? Analyses of data from three randomized controlled trials.Musculoskeletal Care. 2020 Mar; 18: 3-11https://doi.org/10.1002/msc.1425
Chapple CM. Physiotherapy for Osteoarthritis of the Knee: Predictors of Outcome at One Year (Thesis, Doctor of Philosophy). University of Otago; 2012. Retrieved from http://hdl.handle.net/10523/2194.
- 3D kinematics and decision trees to predict the impact of a physical exercise program on knee osteoarthritis patients.Appl Sci. 2021; 11: 834