Achilles tendinopathy (AT) .. there are many factors that can contribute.
Have you considered leg length inequality? Generally speaking, People have a tendency to overpronate on the longer leg side and under prone only shorter leg side with strain on the medial and lateral aspects of the Achilles tendon respectively. It would make sense that this could be a contributing factor.
"The mean inequality in length of legs (ILL) was 5 +/- 4 mm. Among the 48 patients with ILL > or = 5 mm, the side affected with ruptured tendon was longer in 48% of cases and shorter in 52%. " (1)
Age and pathology can play a role with younger, healthy tendons having greater compliance, with compliance being considered a risk factor for AT.(2)
Proprioception is impaired on the affected side of folks with Achilles tendinopathy (3). This is a "chicken and the egg" scenario. Did impaired proprioception cause the tendinopathy or is the tendinopathy causing the impaired proprioception? Probably, a little bit of both.
All this and more to be discussed in one of the 3 cases we will discuss tomorrow evening, Wednesday, August 15th on onlinece.com: Biomechanics 320 5PST, 6 MST, 7 CST, 8 EST
Hope to see you there!
1. Leppilahti J, Korpelainen R, Karpakka J, Kvist M, Orava S. Ruptures of the Achilles tendon: relationship to inequality in length of legs and to patterns in the foot and ankle. Foot Ankle Int. 1998 Oct;19(10):683-7.
2. Intziegianni K, Cassel M, Rauf S, White S, Rector M, Kaplick H, Wahmkow G, Kratzenstein S, Mayer F. Influence of Age and Pathology on Achilles Tendon Properties During a Single-leg Jump. Int J Sports Med. 2016 Nov;37(12):973-978. Epub 2016 Aug 8.
3. Scholes M, Stadler S, Connell D, Barton C, Clarke RA, Bryant AL, Malliaras P. Men with unilateral Achilles tendinopathy have impaired balance on the symptomatic side. J Sci Med Sport. 2018 May;21(5):479-482. doi: 10.1016/j.jsams.2017.09.594. Epub 2017 Oct 6.