Sensitivity and Tests for Evaluation of Plantar Fasciopathy

Condition(s) studied

Investigational drug(s) / intervention(s)

Gastroc Sign: Modified Version of the Royal London Hospital Test (Gastroc Sign) After identifying tenderness at the medial calcaneal tuberosity with the ankle in a neutral or slightly plantarflexed position, participants are asked to actively perform ankle dorsiflexion and plantarflexion with the knee extended. If the tenderness identified in the initial phase decreases or disappears during active dorsiflexion, the test is considered positive.

Tenderness at the Medial Calcaneal Tuberosity: Palpation is performed with the ankle in a neutral position or slight plantarflexion, gently pressing the medial aspect of the plantar heel region starting from the palpable medial calcaneal tuberosity. Participants are asked to report whether tenderness is present or absent.

Silfverskiöld Test: The Silfverskiöld test \[20\] is performed with the patient in the supine position. The examiner uses both hands: one stabilizes and locks the subtalar joint in a neutral position, while the other stabilizes the midtarsal joint and forefoot in supination, ensuring that movement is isolated to the tibiotalar joint. Tibiotalar dorsiflexion is measured under two conditions: * With the knee fully extended * With the knee flexed at 90 degrees Limited dorsiflexion in both positions indicates soleus tightness or a bony block as the cause of stiffness. Reduced dorsiflexion with the knee extended, accompanied by a soft and elastic end-feel, suggests isolated gastrocnemius contracture and is therefore interpreted as a positive Silfverskiöld test.

Study summary

Plantar fasciopathy (PF), one of the leading causes of foot pain, affects up to one in ten individuals in their lifetime. Characterized by pain and structural alterations at the proximal insertion of the plantar fascia on the calcaneus, the term "PF" has replaced "plantar fasciitis," as degenerative tissue changes predominate over inflammatory processes.

The pathogenesis of PF remains incompletely understood but appears to involve the gastrocnemius muscle, which is part of an integrated biomechanical unit including the calcaneus and the plantar fascia. Diagnosis is primarily based on clinical history and physical examination, while imaging modalities such as ultrasound and magnetic resonance imaging assist in excluding differential diagnoses. A simple clinical test to distinguish PF from other causes of heel pain, such as plantar fat pad syndrome or Baxter's nerve entrapment, could improve diagnostic efficiency.

Given the biomechanical relationship between the Achilles tendon and the plantar fascia, and their shared association with gastrocnemius tightness, a clinical test adapted from Achilles tendon assessment may be useful for diagnosing PF. In 2003, the Royal London Hospital proposed a diagnostic approach for Achilles tendinopathy based on pain reduction during active ankle dorsiflexion, which reduces tension in the tendon. The same concept could be applied, with appropriate modifications, to PF.

The present study aims to evaluate the sensitivity, specificity, reproducibility, and predictive value of localized tenderness at the medial calcaneal tuberosity and of a modified version of the Royal London Hospital Test in patients with PF. Secondarily, it will assess the reproducibility and prevalence of the Silfverskiöld test, supporting the concept of a biomechanical unit involving the triceps surae, calcaneus, and plantar fascia.

Aim of this study is to evaluate the sensitivity, specificity, reproducibility, and predictive value of tenderness at the medial calcaneal tuberosity and of a modified version of the Royal London Hospital Test in patients presenting with clinical signs of PF. The modified version of the Royal London Hospital Test for PF has not yet been formally validated in the literature. However, the study was designed following the methodology adopted by Prof. Maffulli for the validation of the original test. Therefore, this is an exploratory study aimed at collecting preliminary data on this new diagnostic test. The secondary objectives of this study is to evaluate the reproducibility and prevalence of the Silfverskiöld test in the study population.

Eligibility

Primary outcome measure(s)

• sensitivity — from the morning to the afternoon of Day 1 - baseline
  To evaluate the ability of tenderness at the medial calcaneal tuberosity and the modified Royal London Hospital Test to correctly identify patients with plantar fasciopathy (true positive rate). Sensitivity reflects the proportion of individuals with PF who are accurately detected by the test.
• Specificity — from the morning to the afternoon of Day 1 - baseline
  To assess the ability of the same clinical tests to correctly identify individuals without plantar fasciopathy (true negative rate). Specificity represents the proportion of non-PF subjects who are correctly classified as negative.
• Reproducibility (Reliability) — from the morning to the afternoon of Day 1 - baseline
  To determine the consistency of the test results when performed by different evaluators (inter-rater reliability) and when repeated by the same evaluator at different time points (intra-rater reliability). This will be quantified using statistical measures such as Cohen's kappa coefficient.
• Predictive Value — from the morning to the afternoon of Day 1 - baseline
  To evaluate the clinical usefulness of the tests in practice: Positive Predictive Value (PPV): the probability that a subject with a positive test result truly has PF. Negative Predictive Value (NPV): the probability that a subject with a negative test result truly does not have PF. These measures depend on disease prevalence and will be recalibrated accordingly.

Trial sites (1)

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