Keywords: Patellofemoral pain, footwear, insoles

In this blog we discuss the findings of our recent study published in BJSM that investigated the effect of biomechanical foot-based interventions on patellofemoral joint loads during gait in people with and without patellofemoral pain or osteoarthritis.

Why is this study important?

Patellofemoral pain, otherwise known as kneecap pain, is a highly prevalent condition affecting young people through to older adults (1). It is defined as pain at or around the patella during activities that load the patellofemoral joint, such as running (2, 3). It is postulated that treatment strategies that reduce patellofemoral joint load may be efficacious for patellofemoral pain. 

Footwear and insoles have been proposed as low-burden treatment approaches that may reduce patellofemoral joint loads and, therefore, improve symptoms (4). As such, clinicians commonly use these interventions, and international guidelines recommend insoles as best practice to treat patellofemoral pain (2,5). 

Despite the biomechanical rationale and widespread use of these interventions, no study has systematically reviewed research investigating the effects of biomechanical foot-based interventions on patellofemoral joint loads.

Therefore, this systematic review and meta-analysis aimed to evaluate the effect(s) of biomechanical foot-based interventions on patellofemoral loads during walking and/or running in adults with and without patellofemoral pain or osteoarthritis.

How did we go about this?

We searched five databases for studies that assessed the effects of biomechanical foot-based interventions (footwear, insoles, taping or bracing) on peak patellofemoral joint loads (quantified by patellofemoral joint pressure, reaction force, or knee flexion moment) during walking or running in people with patellofemoral pain or osteoarthritis. 

Where there were three or more studies that were sufficiently similar, meta-analysis was performed. We assessed the risk of bias using the Cochrane Risk of Bias 2 for randomised cross-over trials and the certainty of evidence from each meta-analysis with the GRADE approach. The GRADE approach considers a range of domains that may make the result of a meta-analysis more or less certain. The ratings and what they mean are in Table 1. 

 

Table 1. GRADE certainty ratings (6)
Certainty	What it means
Very low	The true effect is probably markedly different from the estimated effect
Low	The true effect might be markedly different from the estimated effect
Moderate	The true effect is probably closer to the estimated effect
High	The true effect is similar to the estimated effect

 

What did we find?

The results are summarised below.

Figure 1: Summary of results.  Reduction,   increase, and no difference in PFJ loads from meta-analysis;  Reduction, increase, and no difference in PFJ loads based on one or two individual studies; = no data available; very low (red), low (yellow), moderate (blue), and high (green) certainty evidence according to GRADE; White = GRADE not performed due to limited studies; PFP = patellofemoral pain; PFOA = patellofemoral osteoarthritis.

We identified 33 eligible studies. There were three eligible comparisons during walking and running combined: minimalist vs. conventional footwear, insoles with medial support vs. no insole, and rocker vs. non-rocker footwear. We sub-grouped each analysis by task (walking or running) and population (patellofemoral pain, healthy or patellofemoral osteoarthritis). However, some of these sub-groups were based on one or two studies and we could not draw firm conclusions.

Our analyses showed that minimalist footwear reduced peak patellofemoral joint loads compared to conventional footwear during walking and running combined, and during running only, with low certainty. This result may have clinical relevance considering the cumulative load reduction that would occur over numerous loading cycles during running. The average reduction in patellofemoral joint load during running in minimalist footwear equated to 9.5%. This is equivalent to 18.28*BW (1,462 kg for an 80kg person) less joint force in minimalist footwear compared to conventional footwear over one kilometer (based on a calculation of total force impulse [BW x stance time] x number of steps per kilometer) (7).

In contrast, analyses showed that medial support insoles did not alter patellofemoral joint loads during walking and/or running with low certainty. This suggests that the pain-reducing effects of insoles reported in previous research may be due to influences other than reductions in patellofemoral joint loading, such as contextual factors. Finally, the evidence regarding the effect of rocker-soled shoes during walking and running is very uncertain, largely due to limited studies. 

What are the key take-home points?

• Minimalist footwear may reduce patellofemoral joint loads slightly compared to conventional footwear in people with and without patellofemoral pain during running only. 
• Medial support insoles may not alter patellofemoral joint loads during walking or running in people with patellofemoral pain or osteoarthritis and the evidence is very uncertain about the effect of rocker-soled shoes during walking and running combined.

Authors: Mr Samual A. Kayll, Professor Rana S. Hinman, Associate Professor Adam L. Bryant, Professor Kim L. Bennell, Mr Patrick L. Rowe and Associate Professor Kade L. Paterson.

Reference list

1. Smith BE, Selfe J, Thacker D, et al. Incidence and prevalence of patellofemoral pain: A systematic review and meta-analysis. PLoS One 2018;13(1):e0190892-e92. doi: 10.1371/journal.pone.0190892
2. Willy RW, Hoglund LT, Barton CJ, et al. Patellofemoral pain. Journal of Orthopaedic & Sports Physical Therapy 2019;49(9):CPG1-CPG95. doi: 10.2519/jospt.2019.0302
3. Crossley KM, Stefanik JJ, Selfe J, et al. 2016 Patellofemoral pain consensus statement from the 4th International Patellofemoral Pain Research Retreat, Manchester. Part 1: Terminology, definitions, clinical examination, natural history, patellofemoral osteoarthritis and patient-reported outcome measures. British Journal of Sports Medicine 2016;50(14):839-43. doi: 10.1136/bjsports-2016-096384
4. Nguyen LY, Harris KD, Morelli KM, et al. Increased knee flexion and varus moments during gait with high-heeled shoes: A systematic review and meta-analysis. Gait & Posture 2021;85:117-25. doi: https://doi.org/10.1016/j.gaitpost.2021.01.017
5. Collins NJ, Barton CJ, van Middelkoop M, et al. 2018 Consensus statement on exercise therapy and physical interventions (orthoses, taping and manual therapy) to treat patellofemoral pain: recommendations from the 5th International Patellofemoral Pain Research Retreat, Gold Coast, Australia, 2017. British Journal of Sports Medicine 2018;52(18):1170. doi: 10.1136/bjsports-2018-099397
6. Siemieniuk RG, G. What is GRADE? 2023 [Available from: https://bestpractice.bmj.com/info/toolkit/learn-ebm/what-is-grade/ accessed 23 Mar. 2023.
7. Sinclair J, Richards J, Selfe J, et al. The Influence of Minimalist and Maximalist Footwear on Patellofemoral Kinetics During Running. Journal of Applied Biomechanics 2016;32(4):359-64. doi: 10.1123/jab.2015-0249 [published Online First: 2016/03/10]