Do isometrics reduce pain in rotator cuff tendinopathy?

Dear all,

Welcome to tendinopathy blog 21.

Pleased to announce upcoming Lower Limb Tendinopathy courses throughout Australia, organised by the Aust Physio Association (got to this page and search 'lower limb tendinopathy'). Physios, chiros, osteos, myos, pods and exercise physiologists are welcome. Watch this space as we are working to make costs of these courses the same for all professions.

A couple of interesting articles in this weeks blog (Subscribe here). First a look at a pilot study investigating isometric load and ice for managing pain in acute onset supraspinatus tendinopathy – we are lucky enough to have some insights and comments from the first author too, Phillip Parle. Then we look at ankle dorsiflexion range in the lunge test among insertional Achilles patients with clinical implications galore!

Hope you enjoy.

Peter

Isometrics in rotator cuff tendinopathy

What they did: Interesting study by Parle et al. investigating isometric loading and ice wraps in managing acute (http://www.ismc.org.au/) has been kind enough to fill in some gaps. Thanks Phil!

The authors were particularly interested in early rotator cuff rehab and whether isometrics could re-establish cuff function without provoking symptoms. They randomized people into an ice (n=6), isometric (n=7) and ice+isometric group (n=7). The isometric protocol consisted of external rotation progressing from 3-5 times/day and from 10-20 second holds. ER was performed in standing or sitting with the elbow at 90° flexion and the thumb pointing upwards. ER was resisted with the other arm as shown in the photo below. Participants were asked to build up gradually to approx. 50% of maximum force over 5 seconds. Up to 2/10 pain was allowed and there was a minute rest between sets. Maybe more abduction would have reduced tendon compression? Spoke to Phil about this and they have subsequently modified to holding the elbow a little away from the body.

Interventions were conducted over only a week and outcomes included visual analogue scale (VAS) pain, ER and flexion isometric strength and ultrasound imaging of bursa and tendon. One of the issue with rotator cuff tendinopathy is there is no gold standard in diagnosis. The authors did something clever here in trying to identify acute ones and based diagnosis on ‘an unaccustomed increase in shoulder activity preceding onset of symptoms’ as well as evidence of tendinosis or bursitis on ultrasound imaging. Exclusion criteria included dominant biceps pain, frozen shoulder, full thickness or large partial thickness tears and traumatic onset of pain.

What they found: 5/7 (71%) of participants in the isometric group and 4/6 (67%) in the ice group had reduced VAS pain scores after the week – so both groups improved over time. Important to note there were no significant between group differences and no benefit in combining ice and isometrics. VAS improvement in the isometric group (32%) was higher than the improvement in the ice group (17%) but again it was not significant. This may have been significant with larger numbers. The authors suggest different mechanisms as the ice group was more likely to have reduction of bursa size (significant) and the isometric group was more likely to have reduced tendon thickness (trend). There were no significant differences over time or between groups for ER strength but there was improved flexion strength in both groups. Maybe this is explained by reduced pain inhibition?

Interpretation:  This study shows short term change in pain from isometrics and ice in acute rotator cuff tendinopathy. The big question is would they have changed anyway, that’s were a control group would have been nice. The authors are very honest about this in the limitations section.

They commenced this study prior to the Rio et al. 2015 patellar tendon study and justified the 50% MVC load on the fact that the ‘shoulder clients with pain tend to adopt compensatory ways of movement very early. If you ask them to go hard they tend to reinforce the compensatory movement and this results in overactivity of surrounding muscles such as pec minor, upper traps and rhomboids leading to protraction of the shoulder and potential irritation not to mention overload of cervical structures.’ Very fair point. Not all tendons are equal. We need more info on how isometrics apply to different tendons and the mechanisms (this was also highlighted in a previous blog on isometrics for tennis elbow). Don’t forget also, aside from looking at a different tendon, Rio et al focused on short term change in pain and found change in cortical function may be a mechanism – whether the mechanisms are different with longer term pain changes is not known. Of note on this point, there was no increase in ER isometric strength in either group in the Parle study – would there have been if they had assessed immediately after the isometric loading?

I would like to see an attempt at placebo control with isometric studies. For example, a group that undergoes loading remote the the affected tendon. This will tell us something about mechanisms ie general analgesic effect or patient expectation effect versus effect of load applied locally.  We're back to the most classic of research sayings: MORE RESEARCH NEEDED! :)

Ankle dorsiflexion in insertional Achilles tendinopathy

What they did: Chimenti et al. have investigated dorsiflexion (DF) measured in the weightbearing lunge test in insertional Achilles tendinopathy. One of the issues with the weighbearing lunge test is that DF may occur at the foot as well as the ankle. These authors wanted to explore these contributions when performing the test with a straight and bent knee, as well as whether these contributions differ in people with insertional Achilles pain and controls.

They recruited 16 people with insertional Achilles pain and 16 controls. They used a 3 segment (1st metatarsal, calcaneum, tibia) kinematic 3D motion model to capture foot and ankle motion. They measured gross DF (tibia relative to longitudinal axis of the foot), rearfoot DF (tibia relative to calcaneum) and forefoot DF (first metatarsal relative to the calcaneus). 3D motion was assessed during a standard weightbearing DF lunge test with the knee straight and bent.

What they found: On average, ankle DF was overestimated by 3-5 degrees when foot motion was not considered and this was for both the knee bent and straight tests.

The group with insertional Achilles pain had less ankle DF range but only in the knee bent test (32.2 vs 22.8 degrees). As you would expect this lack of range was from the talocrural joint as they had similar DF range when considering the forefoot DF. This meant that the gross DF range was correlated with both forefoot and rearfoot DF, whereas for the controls gross DF was correlated with only rearfoot DF. Rearfoot eversion was not associated with single-segment DF for either group.

Interpretation: This study confirms that the talocrural joint is not the only joint that contributes to ankle DF on the lunge test. Of more interest in my opinion is the finding that insertional Achilles patients have a) reduced gross DF range with the knee bent test; and b) this is related to reduced range at the talocrural joint (rearfoot ankle DF). The Achilles group had the same range in forefoot DF. So when testing lunge test DF with the knee bent the forefoot contributes more to DF for the Achilles group than in the asymptomatic group, meaning that the talocrural joint may be more restricted than it appears. So consider the medial longitudinal arch collapse (marker of foot DF) when testing weightbearing DF range – I don’t restrict it but simply note it.

It is important to note that 15/16 Achilles participants reported pain with the knee bent lunge test, so this is a likely limiting factor to range. I agree with the authors that simply stretching into lunge positions may result in ‘unwanted effects’, i.e. stretching of the foot rather than talocrural joint. (not to mention compressing the Achilles insertion). So managing pain and load tolerance in DF is the key.

The study raises an interesting question about orthotics indications. eversion/pronation was not correlated with DF in either group so you could argue for medial posting if someone had excessive pronation. However, medial posting may restrict forefoot DF – this may increase Achilles load if we consider that the forefoot DF assists in attenuating forces/shifting load to the foot. In this instance this compensation is probably helpful (it's helpful until load is shifted and leads to an injury elsewhere - the balancing act!). Of course we are thinking very biomechanically here and this is not the only reason to consider tape, orthotics, etc - short term change in pain and function is a good starting point in clinic and the potential mechanisms here are many!

See you next time

Peter