Trunk biomechanics, hip and knee kinematics in patellofemoral pain

Hot on the heels of posts on:

  • This modelling on core muscle activation and knee loads.
  • This study that showed that more of a forward lean of the trunk at the hips resulted in less knee loads, greater hip loads and no effect on ankle loads compared to a forward lean at the ankle results in less knee loads, greater ankle loads and no effect at the knee
  • A lot of other studies on patellofemoral pain and biomechanics.
  • and a number of recent whinges about many of the studies on loads being in asymptomatic people and not people with symptoms.

….comes this study:

Trunk biomechanics and its association with hip and knee kinematics in patients with and without patellofemoral pain
Theresa Helissa Nakagawa, Carlos Dias Maciel, Fábio Viadanna Serrão
Manual Therapy; in press
Patellofemoral pain (PFP) is a common lower extremity condition observed in sports clinics. Recently, it has been suggested that trunk motion could affect hip and knee biomechanics in the frontal plane. Thus, the purpose of the study was compare trunk kinematics, strength and muscle activation between people with PFP and healthy participants. In addition, the associations among trunk biomechanics, hip and knee kinematics were analysed. Thirty people with PFP and thirty pain-free individuals participated. The peak ipsilateral trunk lean, hip adduction, and knee abduction were evaluated with an electromagnetic tracking system, and the surface electromyographic signals of the iliocostalis and external oblique muscle were recorded during single-leg squats. Trunk extension and trunk flexion with rotation isometric strength and side bridge tests were quantified using a handheld dynamometer. Compared with the control group, the PFP group demonstrated increased ipsilateral trunk lean, hip adduction and knee abduction (p = 0.02 – 0.04) during single-leg squat accompanied with decreased trunk isometric strength (p = < 0.001 – 0.009). There was no between-group difference in trunk muscle activation. Only in the control group, ipsilateral trunk lean was significantly correlated with hip adduction (r = -0.66) and knee abduction (r = 0.49); also, the side bridge test correlated with knee abduction (r = -0.51). Differences in trunk, hip and knee biomechanics were found in people with PFP. No relationship among trunk, hip and knee biomechanics was found in the PFP group, suggesting that people with PFP show different movement patterns compared to the control group.

This study looked at both a symptomatic and asymptomatic group and the main findings were:

  • Those with patellofemoral pain had lower trunk isometric strength
  • No difference in trunk muscle activation between the groups
  • Those with patellofemoral pain had greater peak ipsilateral trunk lean, hip adduction and knee abduction during a single-leg squat.
  • Greater ipsilateral trunk lean was correlated with lower hip adduction and greater knee abduction in the control group, but not the patellofemoral pain group
  • The greater lateral trunk strength was associated with lower knee abduction in the pain-free control group
  • There were no relationships among trunk kinematics, muscle strength and activation, and hip and knee kinematics were found in the patellofemoral pain group.

All of this suggests a couple of things to me:

  • the patellofemoral pain group shows different movement patterns compared to the control group
  • chicken or egg?; did the movement pattern predispose to the patellofemoral pain or did the patellofemoral pain alter the movement pattern

I have reviewed several studies on patellofemoral pain syndrome (see this tag) and some of them were on asymptomatic individuals and looked at knee loads and different strategies like foot strike pattern and their effects on knee loads. If those with patellofemoral pain have a different movement pattern are these studies on knee loads in healthy asymptomatic runners applicable to the symptomatic population?

As always, I go where the evidence takes me until convinced otherwise ….and we have to be cautious extrapolating from lab studies on asymptomatic runners to symptomatic ones. I probably have not been as cautious in the past as I should have been.

Nakagawa, T., Maciel, C., & Serrão, F. (2014). Trunk biomechanics and its association with hip and knee kinematics in patients with and without patellofemoral pain Manual Therapy DOI: 10.1016/j.math.2014.08.013

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