There are a number of structures that can cause Achilles pain. It's important to differentiate between these causes, as management will differ for each of these.
In this blog we cover some of the main causes of Achilles tendon pain which includes:
Insertional tendinopathy
Mid portion tendinopathy
Fascia cruris tear
Plantaris tendon
Paratenon
Sural nerve
Insertional versus mid-portion tendinopathy
Mid-portion AT represents 55% to 65% of AT injuries. (Maffulli, N., et al. 2015)
Insertional AT accounts for approx 20% to 25% of AT injuries. (Maffulli, N., et al. 2015)
Location of pain: mid-portion tendinopathy is painful a few inches up from the heel (A on the image right), whereas insertional tendinopathy will be painful lower down at the heel (B on image right)
Insertional worse on high ranges of dorsiflexion
Insertional tendinopathy tends to be more difficult to manage
4cm heel lift often needed for insertional tendinopathy
Fascia cruris tear
Fascia cruris is the layer of connective tissue that encloses all posterior structures of calf down to ankle joint & connects to Achilles paratenon
May play role in paratenon issues due to attachment
Clinically: rapid onset swelling & tenderness over medial or lateral border of mid to upper portion of Achilles, often preceded weeks/days by tightness in calves (Webborn et al 2015)
U/S confirm diagnosis
Management as per soft tissue strain
Partial tears of the Achilles tendon
Partial tear
8% incidence in those with Achilles pain (Chan et al 2017)
Intratendinous tear
5% incidence in those with Achilles pain (Chan et al 2017)
Clinically: can frequently jog without discomfort but unable to push off at speed
Imaging to diagnose U/S or MRI: questions on accuracy
Plantaris involvement
Present in 80% to 100% (Pollock, Dijkstra et al. 2016).
Matter of whether it is invaginated with AT.
End range dorsiflexion & rearfoot valgus can create compression of AT & PT (Stephen, Marsland et al. 2017)
Bend sprinters are particularly affected, predominantly the right leg, suggests mechanical interaction between the PT and AT (Pollock, Dijkstra et al. 2016)
Pain medially, & often more proximal to mid portion vs mid portion tendon they tend to pinch
Palpate tendon: start at muscle tendon junction, feel medially. Normal thickness few mm thick (piano wire thickness), when pathological increase to 8mm
Crepitus (audible with stethoscope) as PT & AT friction against each other.
Dorsiflexion tends to compress PT: behaves more like insertional AT.
Pain on initiation of calf raise when on a decline board.
Differentiate b/w PT and insertional AT by location of the pain
Feel worse when barefoot due to greater dorsiflexion
Manage plantaris like insertional AT: AVOID high dorsiflexion ROM
Heel raise >12mm & shorten stride to limit compression
Research on treatment with surgery, but it can be helped conservatively
Paratenon
Often worse with SLOWER movement (calf raise) vs energy storage-release (hopping)
Treatment: Half voltaren gel, half hirudoid cream. Slather on. Wrap in glad wrap at night for 7 nights in a row
Sural nerve involvement
Pain LATERAL to the tendon
Palpate the nerve, normal nerve will not be painful
Tinel's sign not reliable
Neurodynamic signs ie. slump test
May be linked to presence of third head of gastrocs (found in 1.9%) (Koplas, M. C., et al. 2009)