Introduction

Tibialis posterior tendinopathy is a condition that may affect young active individuals as well as older individuals. It is the most common cause of an acquired flatfoot deformity, which can lead to severe joint deformity at its worst. Since it often remains undiagnosed in the early stages, people tend to develop structural deformities which can lead to activity limitations gradually. Establishing an accurate way of diagnosing this condition is important to avoid people going through this continuum of tendinopathy evolving to rupture with foot deformity. To diagnose this condition, up to now ultrasound examinations and clinical tests are widely used. Although often performed, the International Scientific Tendinopathy Symposium recommends against the use of ultrasound to diagnose tendinopathy. Clinical tests remain important and the reliability of these tests is critical for determining their utility in diagnosing tibialis posterior tendinopathy. Therefore, this study aimed to assess the reliability of common clinical diagnostics tibialis posterior tendinopathy tests and their association with grayscale ultrasonography in people with medial foot/ankle pain. 

Methods

This prospective cohort study included people with medial food and/or ankle pain who were between the ages of 18 and 70 years. Their pain rating was greater than 2/10 on a numeric scale and was present most days for a minimum of 3 months. They were free from any neurological disorder or known medical conditions.

They underwent a clinical assessment where the following tests were examined:

1. Pain on tendon palpation: The tibialis posterior tendon was palpated from the musculotendinous junction to the insertion on the navicular tuberosity as part of this test. If tenderness was detected upon palpation, the test was classified as positive.
2. Swelling surrounding the tendon: The tibialis posterior tendon’s path was examined to determine whether there was any palpable or obvious swelling present. If swelling was detected, the test was classified as positive.
3. Pain/weakness during tibialis posterior contraction: This test assessed pain or weakness during isometric contraction of ankle plantar flexion inversion in a neutral position. If pain or weakness were felt, the test was classified as positive.
4. Pain during or incapacity to do a single-leg heel rise (SLHR): The single-leg heel raise was tested. If the individual felt discomfort during the test or could not complete it, the test was scored positive.

Musculoskeletal ultrasound imaging was performed to assess the tibialis posterior tendon for grayscale changings, which are thought to represent structural tendon pathology. The ultrasound scan was performed by a research radiographer/sonographer with more than 20 years of expertise. The participants were placed with their ankles in a neutral position. The sonographer employed a standardized examination technique, taking longitudinal and transverse views of the tibialis posterior tendon.

This study aimed to compare the people who tested positive to those who did not on both the clinical tests and ultrasound. Also, the reliability of the tibialis posterior tendinopathy tests was examined and the association between the clinical tests and the ultrasound was explored. 

Results

Fifty-two participants with medial ankle and/or foot pain were included in the study. They were on average 46.2 years old and reported having had 6.5/10 pain at its worst over the past week.

Of the 52 participants, 22 had grayscale tendon changes and thus a “positive” ultrasound. Considering the tibialis posterior tendinopathy tests, the study found that:

• Those testing positive on the single-leg heel raise test had a more pronated foot as measured by the Foot Posture Index, had more mobile feet, and were on average 10kg heavier. It was speculated that this increase in midfoot mobility and higher BMI increases the demand on the tibialis posterior tendon since its action is to keep the foot rigid and provide a stable base of support for propulsion.
• Those with a positive test for visible and/or palpable swelling and tenderness on palpation had more pronation of the foot and those with swelling had a higher BMI than those with a positive test. 
• Those who tested positive or negative for pain or weakness on isometric contraction displayed no differences.
• The people with structural changes on ultrasound were on average 10 years older and had more pronated feet.

The examination of the reliability revealed that the Single-Leg Heel Raise test was the test with the highest inter-rater agreement, with a Kappa representing substantial agreement. In 87.5% of cases, the examiners agreed. 

When the ultrasound was compared against the tibialis posterior tendinopathy tests, no meaningful associations were found.

• Pain during the Single-Leg Heel Raise test or the inability to perform this test was the test with the highest association with ultrasound findings. The odds ratio was 5.8 but the confidence interval was imprecise as it ranged from 1.7 to 20.4. 
• The combination of palpation and loading was moderately associated with the ultrasound findings. Here also, the confidence interval was imprecise and ranged from 1.2 to 13.1)
• The ultrasound was positive in almost as many cases that had a positive or negative Single-Leg Heel Raise test result.

Questions and thoughts

This study leads us to conclude that: 

• The Single-Leg Heel Raise test was the most reliable in terms of the inter-examiner agreement. It had the highest association with structural changes on ultrasound. 
• This test was superior to the manually resisted isometric test of ankle plantar flexion and inversion from a neutral position. 
• Tenderness on palpation, on the other hand, was the least reliable test and had a poor association with the ultrasound findings. 
• Ultrasound examination on its own, had no place in diagnosing tibialis posterior tendinopathy since many had positive clinical test findings without structural abnormalities on the ultrasound scan and vice versa. 

Striking to me was that the authors indicated that ultrasound was not necessary to diagnose the condition, a finding confirmed by the International Scientific Tendinopathy Symposium consensus. Yet, they compared common tibialis posterior tendinopathy tests to ultrasound assessment of the tendon to determine the association between the two. They concluded that: “at the group level, a positive Single-Leg Heel Raise test is 6 times more likely to be associated with structural changes on ultrasound than a negative Single-Leg Heel Raise” and thus the best test to diagnose the condition. In the absence of a gold standard, I understand that this was the best way to conduct this study. On the other hand, it seems a bit odd.

In the absence of a gold standard, tibialis posterior tendinopathy remains a clinical diagnosis that can be confirmed by ultrasound, but ultrasound changes on its own cannot be used to diagnose tibialis posterior tendinopathy. The tibialis posterior tendinopathy tests that showed the best association with ultrasound changes were the pain and/or the inability to perform the Single-Leg Heel Raise test or the combination of a positive palpation plus a positive Single-Leg Heel Raise test or resisted plantar flexion inversion. Yet the confidence intervals were wide and thus this association lacked precision.

Talk nerdy to me

This sample had relatively high baseline pain levels and worst pain levels of 4.4/10 and 6.5/10 respectively. We however don’t know for how long they had medial foot or ankle pain. The sample also had a high BMI. You should consider this when comparing your patient to this sample.

The positive was that the authors selected the tests based on the evidence that emerged from their systematic review in 2017. This way they refrained from using all possible movements and tests but kept the analysis simple. 

On the other hand, they used the maximum height Single-Leg Heel Raise but this height was visually observed, which is less reliable. It is possible that some participants did not lift their heels all the way and that this led to less pain provocation and thus a negative test. It would have been better to ensure that the participants went all the way up with their heels and then rate the Single-Leg Heel Raise test as positive or negative.

Further, the authors stated that many people tested positive on palpation but negative on ultrasound. Then they concluded that many other structures in this region may be responsible for the positive pain provocation. Of course, pain on palpation in this region may mean a lot, but the whole point of conducting this study was to find a clinical test to diagnose the condition since we know ultrasound is not able to differentiate between someone with pain and someone without pain (Mills et al. 2020). This study found a poor association between the tibialis posterior tendinopathy tests and the ultrasound, but still seems to rely a lot on the ultrasound findings, which I find odd.

Take home messages

This study examined tibialis posterior tendinopathy tests and found the Single-Leg Heel Raise to be the most reliable and most closely associated with positive ultrasound findings in the tendon. Other tests such as palpation of the tendon, manually resisted contraction of plantar flexion inversion from neutral, and swelling of the tendon were poorly associated with the ultrasound findings and moderately reliable. Ultrasound on its own, can not be used as a diagnostic tool for tibialis posterior tendinopathy.

Reference

Ross MH, Smith MD, Mellor R, Durbridge G, Vicenzino B. Clinical Tests of Tibialis Posterior Tendinopathy: Are They Reliable, and How Well Are They Reflected in Structural Changes on Imaging? J Orthop Sports Phys Ther. 2021 May;51(5):253-260. doi: 10.2519/jospt.2021.9707. Epub 2021 Mar 28. PMID: 33779216. 

Additional reference

Mills FB 4th, Williams K, Chu CH, Bornemann P, Jackson JB 3rd. Prevalence of Abnormal Ultrasound Findings in Asymptomatic Posterior Tibial Tendons. Foot Ankle Int. 2020 Sep;41(9):1049-1055. doi: 10.1177/1071100720931085. Epub 2020 Jun 21. PMID: 32567358.