Has been a busy month – been teaching tendinipathy courses in Spain and the UK, consulting to athletes in the UK, and presenting at a Muscle and Tendon conference hosted by FC Barcelona (a real highlight, had to pinch myself a couple of times)
Some great tendon research this month – enjoy
Attia et al. show a correlation between ground substance content and VISA scores (pain and function) in the patellar tendon. More aggrecan = more pain and dysfunction. Is aggrecan involved in pain or a marker of cell activity or other processes?
Backman et al. show that cultured tenocytes express receptors for TNFa and that TNFa activates apoptotic pathway. Adding substance P can prevent these apoptotic effects. Argue apoptosis important for homeostasis in over-stimulated tendon. Apoptosis counterproductive in end stage pathology?
Boesen et al. show that administering growth hormone in young healthy adults can prevent the normal decline in tendon stiffness with immobilization, and results in increased stiffness and CSA during rehabilitation. Brings up lots of questions about the potential use of GH in management
Nielsen et al. show that manipulation of growth hormone–insulin like growth hormone axis influences tendon morphology and signaling in animal model
Burssens et al. show fibrocartilage differentiation and aggrecan in midportion Achilles. Question is why? Authors suggest that there may be shear and compressive stress on cells in midportion from the known 90 degree rotation of the Achilles or stress gradients. My guess would be increased fluid flow out of the midportion from repetitive SSC load (which makes the tendon more efficient and elastic) exposes tenocytes to compressive overuse and the less permeable aggrecan protects against this.
de Oliveira et al. rat induced diabetes Mellitus model adding to evidence associated metabolic changed may contribute to tendinopathy. A reminder to identify and manage systemic factors associated with tendinopathy in our patients.
Excellent review by Dean et al. generally showing deterioration in histological (eg collagen necrosis), molecular (eg decreased collagen synthesis) and mechanical (eg failure stress) factors following tendon steroid injection. May still have a role for reducing pain in the short term but we need to move away from multiple injections and particularly intratendinous injection – in any tendon!
Dean et al. have written a narrative review of potential shoulder pain mechanisms, discussing primary and secondary hyperalgesia, and central sensitization. Reinforces message to identify and manage signs of central involvement (e.g. diffuse (‘punctate’) hyperalgesia to light touch). Orthopaedic tests often not useful in presence of central pain mechanisms.
Dunkman et al. show that biglycan-null, decorin-null mice have impaired healing. Confirms importance of ground substance-matrix interaction in homeostasis. How healing model relates to tendinopathy unclear.
Great study by Hicks et al. confirming interaction between tendon and fascicle lengthening. Men had stiffer patellar tendons than women, and had less vastus lateralis fascicle elongation during muscle-tendon unit lengthening. Supports idea that tendon is a mechanical buffer during energy storage loading.
Hoogvliet et al. report a systematic review of the effectiveness of exercise and manual therapy in lateral elbow tendinopathy. At best, there is moderate evidence for exercise vs passive treatments, and limited evidence for some manual techniques vs placebo in short term. The McLean et al. (2002) study is excellent in that it shows that manual force levels may influence outcome – so constant re-assessment is critical.
McLean S, Naish R, Reed L, et al. A pilot study of the manual force levels required to produce manipulation induced hypoalgesia. Clin Biomech (Bristol, Avon) 2002;17:304–8.
Kearney et al. interesting pilot study comparing PRP to eccentric loading in Achilles tendinopathy. No significant difference between the groups, but trend towards better outcome in PRP group. This could be because all patients had previously failed non-operative treatments (eg eccentric exercise), or maybe a larger placebo effect of injection vs exercise? Also unclear re return to function instructions given to eccentric group.
Maquirriain et al. show that short term anti-inflamm treatment can improve pain and importantly restore leg stiffness – implications for inseason management
Obst et al. isometrics and long duration static stretching cause immediate reduction in Achilles stiffness whereas prolonged running and hopping have limited effect. Hysteresis and AP diameter may also reduce after dynamic exercise. May increase efficiency and elasticity but increase risk of overuse (Tenocyte compressive/shear load?)
Smith R et al. interesting study showing improved horse tendon structure following mesenchymal stem cell injection. Same questions as PRP – ie will ‘healing’ tendon improve pain? But may be useful for improving tendon function and energy storage
Smith M et al. show glut med and glut max activation is delayed relative to heel strike and shorter duration in running. Could be secondary to pain and injury. May influence sagittal and coronal/frontal plane kinematics and kinetics, eg foot pronation, reduced hip extension, increased ankle power
Wang et al. report a series of lateral elbow tendinopathy patients treated with autologous tenocyte injection – pain and MRI appearance improved – amazing these often unrelated outcomes are positively correlated. There are questions re blinding of MRI outcome assessors and lack of placebo control is an issue. But main question is – DO WE REALLY NEED TO ‘HEAL’ THE TENDON?