Is Postural Control Affected in People with Patellofemoral Pain and Should it be Part of Rehabilitation? A Systematic Review with Meta-analysis

(2022) 8:144 Nunes et al. Sports Medicine - Open https://doi.org/10.1186/s40798-022-00538-4 SYSTEMATIC REVIEW Open Access Is Postural Control Affected in People with Patellofemoral Pain and Should it be Part of Rehabilitation? A Systematic Review with Meta‑analysis Guilherme S. Nunes1* , Diênifer Zilmer Rodrigues1, Luiza Hörbe1, Izabela Prates1, Bruna M. Tessarin2, Fábio V. Serrão2 and Marcos de Noronha3 Abstract Background: Growing evidence supports that exercise therapy is effective for patellofemoral pain (PFP) rehabilitation. Nevertheless, the improvements have been reported not to be sustained in the long term, suggesting that the current protocols may not comprehend all required functional factors to provide a consistent recovery. A potential neglected factor in treatment protocols for PFP is postural control. However, it is unclear whether this population presents balance impairments or the influence of postural control on pain and function during rehabilitation programmes. Objective: To investigate whether (Q1) balance is impaired in people with PFP compared to controls, (Q2) conservative interventions are effective to improve balance in people with PFP, and (Q3) balance exercises are effective to improve pain and function in people with PFP. Data sources: Medline, Embase, CINAHL, SPORTDiscus, Web of Science and Cochrane Library, supplemented by hand searching of reference lists, citations and relevant systematic reviews in the field. Methods: A systematic review with meta-analysis was conducted according to the Cochrane recommendations and reported according to the PRISMA statement recommendations. We included cross-sectional studies comparing balance between people with and without PFP; and randomised controlled trials verifying the effect of conservative intervention on balance and the effect of balance intervention on pain and function in people with PFP. The risk of bias was assessed using the Epidemiological Appraisal Instrument for cross-sectional studies and the Physiotherapy Evidence Database scale for randomised controlled trials. Results: From 15,436 records, 57 studies (Q1 = 28, Q2 = 23, Q3 = 14) met the eligibility criteria. Meta-analyses indicated that people with PFP have worse anteroposterior (very low grade evidence, standardised mean difference [SMD] = 1.03, 95% CI 0.40–1.66) and mediolateral (moderate grade evidence, SMD = 0.87, 95% CI 0.31–1.42) balance compared to controls. Moderate grade evidence indicated that overall balance is not affected in people with PFP (SMD = 0.38, 95% CI − 0.05–0.82). Low to very low grade evidence indicates that interventions are ineffective for mediolateral (SMD = 0.01, 95% CI − 0.51–0.53) and overall (SMD = 0.49, 95% CI − 0.14–1.11) balance improvements, *Correspondence: 1 Department of Physiotherapy and Rehabilitation, Federal University of Santa Maria, Av. Roraima, 1000, Santa Maria, RS CEP 97105‑900, Brazil Full list of author information is available at the end of the article © The Author(s) 2022. Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/. Nunes et al. Sports Medicine - Open (2022) 8:144 Page 2 of 20 and low grade evidence indicates that interventions are effective to improve anteroposterior balance (SMD = 0.64, 95% CI 0.04–1.23). Moderate to low grade evidence indicated that balance interventions are effective to reduce pain (SMD = 0.82, 95% CI 0.26–1.38) and improve function (SMD = 0.44, 95% CI 0.09–0.80) when measured using questionnaires; and very low grade evidence indicated no efficacy for function measured via functional tests (SMD = 0.73, 95% CI − 0.16–1.61). Conclusion: People with PFP likely present balance deficits compared to asymptomatic people. There was insufficient evidence to support the efficacy of interventions to improve or modify balance in people with PFP. Also, there was insufficient evidence to support the efficacy of balance exercises to improve pain and function in people with PFP. Trial Registration The present systematic review was registered in PROSPERO (CRD42018091717). Keywords: Anterior knee pain, Knee, Balance, Exercise, Treatment Key Points • Balance is likely impaired in people with patellofemoral pain compared to asymptomatic people. • It is uncertain whether conservative interventions are effective in improving balance in people with patellofemoral pain. • The efficacy of exercise programmes that included balance exercise to address pain or function in people with patellofemoral pain is arguable. Introduction Patellofemoral pain (PFP) is a frequent disorder in the general population, with an annual prevalence of up to 23% [1]. In the USA, more than two million people were diagnosed with PFP between 2007 and 2011 [2]. This condition has no spontaneous recovery [3, 4] and, therefore, requires treatment [5]. Growing evidence supports that exercise therapy protocols are effective rehabilitation for people with PFP [5–8]. However, pain and function improvements have been reported not to be sustained in the long term [6, 9, 10]. This indicates that the current protocols may not comprehend all required functional factors to provide a full and consistent recovery for that population. A potential neglected factor in treatment protocols for PFP is postural control [5, 11–14]. Postural control involves a complex integration of visual, vestibular and somatosensory systems based on reflex actions occurring to maintain balance [15–17]. Considering people with PFP have impaired H-reflex [18, 19], it is reasonable to expect that people with PFP will have alterations in other neuromuscular reflexes which may impact balance. Additionally, the presence of pain in people with PFP may also lead to impairments in postural control [20, 21]. The nociceptive information potentially impairs information from mechanoreceptors [20, 21], and consequently, may delay reflexes and actions required to maintain balance [20–22]. Some studies have evaluated balance in people with PFP; however, the respective results are conflicting [23–27]. For example, Saad et al. [27] reported that females with PFP have a greater centre of pressure (CoP) displacement during a stair ascent task compared to asymptoma (...truncated)