Dear all

Hope the year has started well

Looking forward to our first biomechanics and tendinopathy courses for 2014 – both coming up over the next couple weeks

Some interesting tendon research and debate in the tendinopathy world this month – full details below

Best wishes



Mishra et al. 2013 published an RCT comparing PRP and steroid for lateral elbow tendinopathy/tennis elbow – it was included in the August 2013 tendinopathy blog. Three individuals/groups (wow!) have written letters challenging the validity of the conclusions (PRP was superior at 24 months) based on several factors – incorrect data analysis, large drop out rate, no definition of the primary outcome, changing the outcome period from 12 to 24 weeks (allegedly because they found no effect) – some major limitations. A good read, particular to brush on up your research quality assessment skills.


Alfredson and Isaksson 2014 report the outcome of 24 consecutive operative cases for recalcitrant insertional Achilles tendinopathy. The usual story for a case series, most are satisfied (83%) and had returned to ‘tendon loading activities’. What is unclear is did they return to previous level of activity? In my experience many don’t, unless they are committed to prolonged and thorough rehab.


Ramirez et al. report ultrasound features in greater trochanteric pain syndrome in 34 patients with spondyloarthropathy and 48 patients with ‘non-inflammatory’ symptoms. They report no difference in ultrasound pathology featured – tendinosis, erosions, calcifications, bursitis. Suggests that regardless of driver (LOAD vs SYSTEMIC), the biological cascade and subsequent disease are similar.


Great study by Janssen et al. showing that men jump higher, have less dynamic valgus, and generate greater knee extensor moments in lateral stop jump landing (volleyball). When men and women were matched for jump height, patellar tendon load was similar – suggests being able to jump high rather than gender relates to PT load and injury risk. Did females who jumped higher have less knee dynamic valgus on landing?


Ying et al 2014 show that patellar tendon stiffness and oxygen saturation increase concurrently immediately following leg extension eccentric knee loading. Maybe build up of aggrecan in early tendon pathology dampens reduced stiffness with loading, and this may effect blood flow? Or maybe these factors are simply correlated.


Review by Kjaer and Heinemeier on acute and chronic effects of eccentric exercise on normal and abnormal tendon. In normal tendon they argue that acute biochemical response in animal models is similar for different contraction types/load. Also argue that clinically, eccentrics and eccentric-concentric protocols may improve symptoms. It is good to highlight that clinical and tendon effects of eccentrics may be similar to other loading, but there is clear evidence that strain (a product of load intensity and time under tension) is associated with tendon adaptation (Arampatzis et al. 2007). Isolated eccentrics is one way to achieve greater strain by maximizing external load. The question is are there other unique effects/outcomes of eccentrics that we can harness for some patient groups, eg force fluctuations, motor control, placebo, etc

Arampatzis A, Karamanidis K, Albracht K: Adaptational responses of the human Achilles tendon by modulation of the applied cyclic strain magnitude. Journal of Experimental Biology. 2007, 210:2743-2753.


Marqueti et al. show that, as expected, anabolic steroids inhibited the positive effects of exercise on tendon adaptation in a rat model.


Interesting study by Mersmann et al showing that adolescent athletes had similar muscle strength and CSA but lower tendon CSA and greater tendon stress than older athletes. May have implications for tendon and even apophysis injuries in adolescent athletes. Fits in with tendon response to load being slow and sluggish compared to muscle.


Monto argues the case for PRP in plantar fasciitis. Abstract is interesting – argues that conventional treatments have limited evidence base, and PRP has recently been shown to be effective in treating recalcitrant tendinpathies (what??!! – please read the letters in the first blog link if you are wondering what my shock is about). The author discusses several case series and non randomized studies, and an RCT that is not published in full form. Blog readers would know that I am not a fan of PRP, but I would consider it for many tendons at the right time, EXCEPT plantar fascia – a nightmare in my experience, but I’m biased by seeing lots and lots of the failures that may get lost to follow-up in studies.


Nice paper from Pearson et al. reigniting the debate regarding stress shielding in the patellar tendon. They show significantly greater strain during isometric knee extension in the anterior compared with posterior and middle layers. Almekinders et al. 2002 also found less strain in the posterior patellar tendon fibres, whereas Basso et al. found the opposite (greater strain in the posterior fibres) – Basso measured strain over the length of the tendon that may not reflect what is happening at the insertion, where the pathology usually is. Basso also reported compression of the patellar tendon at the deep inferior patella pole, which contradicts a finite element model by Lavignino 2008, which showed primarily tensile, not compressive loads at the inferior pole patellar tendon insertion. So there is debate about loads at the inferior pole. What is clear is that tendon stress is increased with knee flexion and this is the important clinical point.

Almekinders LC, Vellema JH, Weinhold PS: Strain patterns in the patellar tendon and the implications for patellar tendinopathy. Knee Surgery, Sports Traumatology, Arthroscopy. 2002, 10:2-5.

Basso O, Amis AA, Race A, Johnson DP: Patellar tendon fiber strains: their differential responses to quadriceps tension. Clinical orthopaedics and related research. 2002, 400:246-253.

Lavagnino M, Arnoczky SP, Elvin N, Dodds J: Patellar Tendon Strain Is Increased at the Site of the Jumper’s Knee Lesion During Knee Flexion and Tendon Loading Results and Cadaveric Testing of a Computational Model. The American Journal of Sports Medicine. 2008, 36:2110-2118.


Thorpe et al. and co workers have previously shown that fascicles are arranged in helical sub-structures in energy storage tendons that facilitate stretch and recoil. In this study they show a significant decrease in ‘unwinding’ of these helical sub-structures with fatigue loading of tendon fascicles – may be involved in pathology mechanisms