Reduced knee flexion is a possible cause of increased loading rates in individuals with patellofemoral pain


      • Individuals with patellofemoral pain presented reduced knee flexion during stair climbing.
      • Individuals with patellofemoral pain presented increased loading rates during stair climbing.
      • Reduced knee flexion as a mechanism of protection could generate increased loading rates.
      • Our findings suggest a focus on knee flexion compensations during functional movement tasks.



      Stair ascent is an activity that exacerbates symptoms of individuals with patellofemoral pain. The discomfort associated with this activity usually results in gait modification such as reduced knee flexion in an attempt to reduce pain. Although such compensatory strategy is a logical approach to decrease pain, it also reduces the normal active shock absorption increasing loading rates and may lead to deleterious and degenerative changes of the knee joint. Thus, the aims of this study were (i) to investigate whether there is reduced knee flexion in adults with PFP compared to healthy controls; and (ii) to analyze loading rates in these subjects, during stair climbing.


      Twenty-nine individuals with patellofemoral pain and twenty-five control individuals (18–30 years) participated in this study. Each subject underwent three-dimensional kinematic and kinetic analyses during stair climbing on two separate days. Between-groups analyses of variance were performed to identify differences in peak knee flexion and loading rates. Intraclass correlation coefficient was performed to verify the reliability of the variables.


      On both days, the patellofemoral pain group demonstrated significantly reduced peak knee flexion and increased loading rates. In addition, the two variables obtained high to very high reliability.


      Reduced knee flexion during stair climbing as a strategy to avoid anterior knee pain does not seem to be healthy for lower limb mechanical distributions. Repeated loading at higher loading rates may be damaging to lower limb joints.


      To read this article in full you will need to make a payment
      Subscribe to Clinical Biomechanics
      Already a print subscriber? Claim online access
      Already an online subscriber? Sign in
      Institutional Access: Sign in to ScienceDirect


        • Briani R.V.
        • De Oliveira Silva D.
        • Pazzinatto M.F.
        • De Albuquerque C.E.
        • Ferrari D.
        • Aragão F.A.
        • et al.
        Comparison of frequency and time domain electromyography parameters in women with patellofemoral pain.
        Clin. Biomech. 2015; 30: 302-307
        • Buckwalter J.A.
        • Anderson D.D.
        • Brown T.D.
        • Tochigi Y.
        • Martin J.A.
        The roles of mechanical stresses in the pathogenesis of osteoarthritis: Implications for treatment of joint injuries.
        Cartilage. 2013; 4: 286-294
        • Cook T.M.
        • Farrell K.P.
        • Carey I.
        • Gibbs J.M.
        • Wiger G.E.
        Effects of restricted knee flexion and walking speed on the vertical ground reaction force during gait.
        J. Orthop. Sports Phys. Ther. 1997; 25: 236-244
        • Crossley K.
        Is patellofemoral osteoarthritis a common sequela of patellofemoral pain?.
        Br. J. Sports Med. 2014; 48: 409-410
        • Crossley K.M.
        • Cowan S.M.
        • Bennell K.L.
        • McConnell J.
        Knee flexion during stair ambulation is altered in individuals with patellofemoral pain.
        J. Orthop. Res. 2004; 22: 267-274
        • De Oliveira Silva D.
        • Briani R.V.
        • Pazzinatto M.F.
        • Ferrari D.
        • Aragão F.A.
        • Albuquerque C.E.
        • et al.
        Reliability and differentiation capability of dynamic and static kinematic measurements of rearfoot eversion in patellofemoral pain.
        Clin. Biomech. 2015; 30: 144-148
        • Farrokhi S.
        • O’Connell M.
        • Fitzgerald G.K.
        Altered gait biomechanics and increased knee-specific impairments in patients with coexisting tibiofemoral and patellofemoral osteoarthritis.
        Gait Posture. 2015; 41: 81-85
        • Ferrari D.
        • Kuriki H.U.
        • Silva C.R.
        • Alves N.
        • Mícolis de Azevedo F.
        Diagnostic accuracy of the electromyography parameters associated with anterior knee pain in the diagnosis of patellofemoral pain syndrome.
        Arch. Phys. Med. Rehabil. 2014; 95: 1521-1526
        • Grenholm A.
        • Stensdotter A.K.
        • Häger-Ross C.
        Kinematic analyses during stair descent in young women with patellofemoral pain.
        Clin. Biomech. 2009; 24: 88-94
        • Hamel K. a
        • Okita N.
        • Bus S. a
        • Cavanagh P.R.
        A comparison of foot/ground interaction during stair negotiation and level walking in young and older women.
        Ergonomics. 2005; 48: 1047-1056
        • Kadaba M.P.
        • Ramakrishnan H.K.
        • Wootten M.E.
        Measurement of lower extremity kinematics during level walking.
        J. Orthop. Res. 1990; 8: 383-392
        • Lankhorst N.E.
        • Bierma-Zeinstra S.M. a
        • van Middelkoop M.
        Factors associated with patellofemoral pain syndrome: A systematic review.
        Br. J. Sports Med. 2013; 47: 193-206
        • Liao T.
        • Yang N.
        • Ho K.
        • Farrokhi S.
        • Powers C.M.
        • Perry J.
        • et al.
        Femur rotation increases patella cartilage stress in females with patellofemoral pain.
        Med. Sci. Sports Exerc. 2015; (Epub ahead of print)
        • Liikavainio T.
        • Isolehto J.
        • Helminen H.J.
        • Perttunen J.
        • Lepola V.
        • Kiviranta I.
        • et al.
        Loading and gait symmetry during level and stair walking in asymptomatic subjects with knee osteoarthritis: Importance of quadriceps femoris in reducing impact force during heel strike?.
        Knee. 2007; 14: 231-238
        • Liikavainio T.
        • Bragge T.
        • Hakkarainen M.
        • Karjalainen P.a.
        • Arokoshi J.P.
        Gait and muscle activation changes in men with knee osteoarthritis.
        Knee. 2010; 17: 69-76
        • Loy D.J.
        • Voloshin A.S.
        Biomechanics of stair walking and jumping.
        J. Sports Sci. 1991; 9: 137-149
        • Maquet P.G.
        Biomechanics of the Knee. 2nd ed. Springer, New York1984
        • McNitt-Gray J.L.
        • Yokoi T.
        • Millward C.
        Landing strategies used by gymnasts on different surfaces.
        J. Appl. Biomech. 1994; 10: 237-252
        • Mündermann A.
        • Dyrby C.O.
        • Andriacchi T.P.
        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
        • Powers C.M.
        • Heino J.G.
        • Rao S.
        • Perry J.
        The influence of patellofemoral pain on lower limb loading during gait.
        Clin. Biomech. 1999; 14: 722-728
        • Radin E.L.
        • Eyre D.
        • Kelman J.L.
        • Schiller a L
        Effect of prolonged walking on the joints of sheep.
        J. Biomech. 1982; 15: 487-492
        • Radin E.L.
        • Whittle M.W.
        • Yang K.H.
        • Jefferson R.J.
        • Rodgers M.M.
        • Kish V.L.
        The heel strike transient, its relationship with the angular velocity of the shank, and the effect of quadriceps paralysis.
        in: Advances in Bioengineering, first edition. 1986: 121-123 (New York)
        • Radin E.L.
        • Yang K.H.
        • Riegger C.
        • Kish V.L.
        • O’Connor J.J.
        Relationship between lower limb dynamics and knee joint pain.
        J. Orthop. Res. 1991; 9: 398-405
        • Rathleff M.S.
        • Roos E.M.
        • Olesen J.L.
        • Rasmussen S.
        • Arendt-Nielsen L.
        Lower mechanical pressure pain thresholds in female adolescents with patellofemoral pain syndrome.
        J. Orthop. Sports Phys. Ther. 2013; 43: 414-421
        • Salsich G.B.
        • Brechter J.H.
        • Powers C.M.
        Lower extremity kinetics during stair ambulation in patients with and without patellofemoral pain.
        Clin. Biomech. 2001; 16: 906-912
        • Stacoff A.
        • Diezi C.
        • Luder G.
        • Stüssi E.
        • Kramers-De Quervain I. a
        Ground reaction forces on stairs: Effects of stair inclination and age.
        Gait Posture. 2005; 21: 24-38
        • Utting M.R.
        • Davies G.
        • Newman J.H.
        Is anterior knee pain a predisposing factor to patellofemoral osteoarthritis?.
        Knee. 2005; 12: 362-365
        • Winter D.
        Biomechanics and Motor Control of Human Movement. 4th ed. 2009 (New York)