Differential Diagnosis of Tendinopathy
Tendinopathies can be notoriously difficult to treat. They are also challenging to diagnose. Tendons often present as pathological on imaging but are entirely asymptomatic. When considering the diagnosis of tendinopathy, the aim is not to determine if the tendon has pathology. But instead to determine whether or not the tendon is the source of pain. Many structures can be implicated when only one aspect is viewed in isolation. For example, anterior knee pain is a clinical finding in patella tendinopathy but, is also a key symptom in patellofemoral pain. By looking at the patient's entire clinical picture, the correct diagnosis can be made.
Tendon Load and Capacity
Tensile, compressive and shearing loads can play a role in the development of tendon pathology. Diagnosing which type of load caused the dysfunction can guide treatment.
Helpful Clues to Diagnose Tendon Related pain
- Pain is related to overload.
- Pain increases with loading and immediately lessens when the load is removed
- Pain is very localised to the tendon 
- Pain should increase when the load applied to the tendon increases (dose-dependent loading), e.g. a shallow squat would be less painful than a deep squat in patella tendinopathy.
- Pain should stay localised during loading activities (this may not be true in all tendinopathies eg gluteal tendinopathy can refer down the leg)
- Pain tends to improve during activity (warm-up phenomenon) but may be worse the day after high loading activities
- Isometric exercises often decrease pain originating from a tendon (if isometrics aggravate the pain possibly consider a different diagnosis)
- Area-specific signs such as morning stiffness for Achilles and sitting for hamstring tendons
Palpation of Tendons
Localised pain on tendon palpation can be an indicator of pathology within a tendon, but this cannot be used in isolation. Tendons can be painful on palpation but not be part of the patient's clinical picture. The absence of pain on palpation may be helpful to rule out tendinopathy.
The absence of tendon pathology can be helpful to rule out tendon pathology. However, the presence of tendon pathology on imaging does NOT implicate the tendon as the source of a patient's symptoms.
Ultrasound and MRI can be used in the diagnosis of tendinopathy. Imaging should be done with care and should be matched with a patient's clinical presentation. Tendons can be viewed very successfully on ultrasound, and it is significantly cheaper than an MRI. Interpretation of MRI results should be done with care. MRI is very detailed and can show pathology that has no relation to the patient's symptoms. Imaging results should be interpreted with caution. Tendons may still appear to be affected on imaging, but the patient ouldhhavesignificant improvements in pain and function. Communicating this to a patient may be helpful to decrease the threat value of findings on imaging.
- Cook J. Jill Cooks latest tendon nuggets clinical pearls Slides. Accessed 8 August 2019 https://sportsphysiotherapy.org.nz/sportsphysiotherapy.org.nz/documents/jill.pdf
- Malliaras P, Cook J, Purdam C, Rio E. Patellar tendinopathy: clinical diagnosis, load management, and advice for challenging case presentations. journal of orthopaedic & sports physical therapy. 2015 Nov;45(11):887-98.
- Rio E. Differential Diagnosis of Tendinopathys Video. Physioplus. 2019
- Kaux JF, Forthomme B, Le Goff C, Crielaard JM, Croisier JL. Current opinions on tendinopathy. Journal of sports science & medicine. 2011 Jun;10(2):238.