THE ASSOCIATION BETWEEN GASTROCNEMIUS ENDURANCE AND THE PRESENCE OF PATELLOFEMORAL PAIN IN ADULTS

A. Vaswani^1,2, J. Lane¹, E. Atkins^1,3

¹Queen Margaret University, Health Sciences, Edinburgh, United Kingdom, ²Haute Ecole de Santé Vaud, Physiotherapy, Lausanne, Switzerland, ³Society of Musculoskeletal Medicine, Liverpool, United Kingdom

Background: Patellofemoral pain (PFP) is characterised by pain around the patella increased by activities such as stair climbing, squatting, running or jumping. It affects young and active individuals and impacts quality of life.
PFP has a complex and multifactorial aetiology. It is associated with abnormal loading of the patellofemoral joint, resulting from local and remote mechanisms. Being part of the lower limb kinetic chain, gastrocnemius contributes to absorption of ground reaction forces and is active during activities that elicit pain in subjects with PFP.

Purpose: The main aim of the study was to evaluate gastrocnemius endurance in adults with PFP and compare it to healthy controls. A secondary aim was to measure the association between gastrocnemius endurance, function, pain and duration of symptoms in adults with PFP.

Methods: This monocentric cross-sectional study was conducted in Switzerland. Ethical approval was granted by the relevant ethics committees. Participants were adults between 20 and 40 years either with a diagnosis of PFP or healthy controls recruited from the local community. Informed consent was obtained prior to participating.
Collected data included demographic information, evaluation of knee function (Anterior Knee Pain Scale) and measurement of gastrocnemius endurance (unilateral heel-rise test) on both sides allowing to calculate the limb symmetry index (LSI). An unrelated t test was used to compare the LSI between groups and the Pearson correlation coefficient was used to analyse the correlation between endurance, function, pain and symptom duration within the PFP group.

Results: The study included 17 females (7 in the PFP group and 10 in the control group). It was a sample of convenience. The 2 groups had similar demographics but differed significantly in terms of exercise time per week (p < 0.001) and knee function (p < 0.001). The mean LSI was 82.9% in the PFP group and 90.3% in the control group. The between-group difference was statistically significant (t(15) = -2.801, p = 0.013), and the effect size was very large (Cohen’s d= 1.29). There was no statistically significant correlation between the LSI and knee function (r = 0.486 ; p = 0.269) or pain (r = -0.327 ; p = 0.474). There was a strong and statistically significant negative correlation between the LSI and duration of symptoms (r = -0.889 ; p = 0.007).

Conclusions: The study found that females with PFP displayed reduced gastrocnemius endurance symmetry compared to controls. Additional analysis within the PFP group showed that a longer duration of symptom correlated with greater gastrocnemius endurance asymmetry. However, these results should be considered as trends for women between 20 and 40 years of age as the sample size was small.

Implications: Findings from this study highlight the need for an in-depth assessment of the whole kinetic chain in PFP as impairments may extend remotely. It is especially important in patients with a longer duration of symptoms as more extended impairments may contribute to increased knee joint load and symptom persistence. Evaluating gastrocnemius endurance with the unilateral heel-rise test is relevant.

Funding acknowledgements: This was not a funded study.

Keywords:
patellofemoral pain
gastrocnemius endurance
physiotherapy assessment

Topics:
Musculoskeletal: lower limb
Musculoskeletal: peripheral
Sport & sports injuries

Did this work require ethics approval? Yes

Institution: Queen Margaret University (Edinburgh, United Kingdom)

Committee: Ethics Committee Vaud (Lausanne, Switzerland)

Ethics number: 2021-01077