For patients with unilateral plantar heel pain (PHP), a regression analysis found that demographic, clinical, psychological, and neurophysiological characteristics had important interactions with function and pain intensity. These findings were published in Pain Medicine.

Between 2020 and 2021, patients with unilateral PHP (N=54) were recruited at a tertiary physical therapy clinic in Spain. Patients were assessed for pain using the 11-point numerical point rate scale (NPRS) and function using the Foot Function Index (FFI). These pain features were related with demographic and clinical characteristics, depression level, and the neuro-physiological variables pressure pain thresholds (PPT) and trigger points.

Patients were aged mean 41±13.5 years, 48% were women, body mass index (BMI) was 28.1±16.0 kg/m2, they had been experiencing pain for 23.9±28.1 months, and NPRS was 5.8±2.0 points. Stratified by gender, women reported higher NPRS pain (P <.001), pain scale (P <.001), and disability scale (P <.001) scores.


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Pain intensity was positively correlated with gender (r, 0.577; P <.01), time in standing position (r, 0.402; P <.01), and number of trigger points (r, 0.240; P <.05) and negatively correlated with calcaneus PPT (r, -0.471; P <.01) and months with pain (r, -0.301; P <.05).

FFI total score was positively correlated with gender (r, 0.507; P <.01), Beck Depression Inventory (BDI-II) score (r, 0.314; P <.05), and age (r, 0.233; P <.05) and negatively correlated with EuroQol-5D score (r, -0.425; P <.01), calcaneus PPT (r, -0.358; P <.01), flexor digitorum brevis muscle belly PPT (r, -0.350; P <.01), and abductor hallucis muscle belly PPT (r, -0.347; P <.01).

In the full model, predictors for mean intensity of foot pain were gender (β, 2.719; P <.001), calcaneus PPT (β, -0.429; P =.001), time in standing position (β, 0.210; P =.007), and FFI total score (β, 0.025; P =.028). Together, these variables explained 60.8% of the variance.

The predictors for FFI total score were gender (β, 13.109; P <.001), EuroQol-5D score (β, -55.574; P <.001), age (β, 0.437; P =.002), BDI-II (β, 0.682; P =.002), and calcaneus PPT (β, -1.892; P =.046), explaining 52.4% of the variance.

This study may have been limited by not including physical variables, such as thickness of the plantar fascia.

The study authors concluded that pain intensity and foot function were partially explained by demographic, clinical, psychological, and neuro-physiological variables. Additional longitudinal study is needed to assess whether any of these variables may be intervention targets for patients with unilateral PHP.

Reference

Alburquerque-Sendín F, Ríos-Léon M, Valera-Calero JA, et al. Clinical, psychological and neuro-physiological outcomes associated with pain and function in individuals with unilateral plantar heel pain. Pain Med. 2022;pnac018. doi:10.1093/pm/pnac018