Achilles Tendon Structure, Function Differs Depending on Pain or No Pain

Aimie Patience, PhD

Credit: ResearchGate

A recent study observed patients with psoriatic arthritis (PsA) who self-reported Achilles tendon pain showed significant Achilles functional impairment and lower PsA-related quality of life compared to PsA patients who did not self-report pain and healthy controls.¹

“This study presents and brings together novel findings around the pathology, structure, and function of the [Achilles tendon] in people with PsA with and without self-reported [Achilles tendon] pain,” wrote investigators, led by Aimie Patience, PhD, from the Musculoskeletal Health Research Group at Glasgow Caledonian University in the UK.

Enthesitis, a clinical feature of PsA with the insertion of the Achilles tendon, creates pain, swelling, and inflammation at the insertion sites. Enthesitis is managed through treatments such as NSAIDS, physiotherapy, corticosteroid injection, conventional disease-modifying anti-rheumatoid drugs (csDMARDs), and biologics (bDMARDs).

According to the Arthritis Foundation, enthesitis does not respond well to oral DMARDs.² A corticosteroid injection is recommended if a patient only has enthesitis in 1 location. If the symptoms persist or occur in several places, a biologic drug is recommended, with a TNF inhibitor as the first choice for most patients.

Although understanding the inflammatory and structural pathology of the Achilles tendon may help inform future treatment options, the pathology is not fully known. Investigators conducted a cross-sectional, observational study to assess the structure and function differences between PsA patients who self-reported Achilles tendon pain, PsA patients who did not, and healthy controls matched by age and sex.¹ Participants (aged ≥ 18 years) with PsA were recruited from the NHS Greater Glasgow and Clyde rheumatology outpatients from January 2020 to February 2022 and healthy controls were recruited from Glasgow Caledonian University.

The team assessed the Achilles tendon through clinical and ultrasound examination (B-mode and Power Doppler), performance-based evaluations (bilateral heel raise test and 100minute walk), and patient-reported outcomes measures such as the Victorian Institute of Sport-Assessment-Achilles (VISA-A).

The 3 groups had no significant differences in sex (P = .887), age (P = .347), or body mass index (BMI) (P = .164). When comparing only the 2 PsA groups, the 1 with self-reported Achilles tendon pain had a significantly greater disease duration than the group with no self-reported pain (P = .019). Age and BMI were also not significantly different between the 2 PsA groups (P = .193 and P = .152, respectively).

The self-reported pain PsA group had a variation in the duration of Achilles tendon symptoms, with a median of 2 years but ranging from 0.25 to 20 years. Three of the participants experienced symptoms before their PsA diagnosis, ranging from 2 to 6 years before.

Additionally, there were significant group differences regarding the presence of Achilles tendon involvement on LEI (P = .001), self-reported current Achilles tendon pain (P < .001), self-reported Achilles tendon morning stiffness (P < .001), pain on the passive dorsiflexion of the ankle (P = .011), and pain on the resisted plantarflexion of the ankle (P = .003).

Investigators saw the heel raise repetition rate was significantly different between PsA groups (P = .005) and between both PsA groups and healthy controls (P = .008).

Many PsA patients who self-reported Achilles tendon pain—but not all—had a greater prevalence of inflammatory features of enthesitis, such as hypoechogenicity, tendon thickening, and Power Doppler signal. VISA-A scores were significantly worse in PsA patients with self-reported pain compared to PsA patients with no self-reported pain and healthy controls (P < .0001).

Furthermore, PsA patients who self-reported pain demonstrated the greatest number of inflammatory characteristics of Achilles Tendon pathology when examined by a clinician (P < .001), including mid-portion Achilles tendon pathology.

“In this study, mid-portion [Achilles tendon] tendinopathic changes, intra-substance mid-portion tears, and retrocalcaneal bursitis were observed on [ultrasound] in both PsA groups,” investigators wrote. “This again highlights the potential clinical utility of using [ultrasound] to define the underlying pathology at the [Achilles tendon] and use this to tailor treatment accordingly.”

Tendon loading tests, examining pain on passive dorsiflexion and pain on resisted plantarflexion, showed this group had a greater number of positive results for Achilles tendon tendinopathy.

Investigators observed the PsA patients with self-reported pain had significant Achilles tendon function deficits. Despite experiencing pain, less than a third of this group received podiatry or physiotherapy care. One similarity between the 2 PsA groups was that they both had lower hormone replacement therapy repetition rates and walked slower compared to healthy controls.

The team noted the clinical examination only picked up on 2/7 (28.6%) cases of [ultrasound] “active” enthesitis features with the Doppler signal.

“This study adds to a body of evidence that suggests there is a poor correlation between clinical assessment for AT enthesitis (palpatory tenderness) and [ultrasound] findings,” investigators wrote.

References

1. ^{Patience A, Steultjens M, Siebert S, Hendry G. Significant functional impairment and disability in individuals with psoriatic arthritis and Achilles tendon pain: a cross-sectional observational study. Rheumatol Int. Published online June 8, 2024. doi:10.1007/s00296-024-05629-x}
2. ^{Gower, T. Enthesitis and PsA. Arthritis Foundation. https://www.arthritis.org/health-wellness/about-arthritis/related-conditions/physical-effects/enthesitis-and-psa. Accessed June 19, 2024.}