The aim of this blog is to briefly discuss the role of injection based therapies in musculoskeletal disorders and identify when they may be of benefit.
Injection therapy, specifically steroid injections such as cortisone, have been around for a long time in the treatment of soft tissue injuries such as tendons and ligaments. Over the past few years this type of treatment has been joined with the advent of PRP injections and High volume infiltration.
In this blog we will have a look at these treatments to explain the theory underpinning them and who they may or may not help.
This is probably the most common one that we encounter as part of someones treatment, especially if they have been diagnosed with bursitis or a tendon related issue.
Hydrocortisone is a synthetic form of cortisol , which is a necessary hormone produced in our body and plays a role in metabolisim of the body’s cells and also how we regulate our bodies reaction to stress, trauma, infections and inflammation.
What do Corticosteroid injections do ?
Steroids work through our immune system to block the production of inflammatory chemicals produced by the body. This in turn reduces the inflammatory response and leading to less or no pain at the injured tissues.
Steroid injections are usually directed into a joint, muscle, tendon, bursa, or a space around these structures. The location will depend on what tissue is causing the symptoms.
Do cortisone injections work and do they cause harm?
Cortisone injections have their place in certain circumstances. For acutely painful structures, e.g bursa , they may be appropriate early on to settle the acute pain if normal strategies of NSAIDs, ice, relative rest, appropriate loading , (read more here )don’t work.
As cortisone is known to weaken cartilage and collagen tissue their use in treatment of these injuries has to be considered carefully. Ideally after the injection a period of relative rest is advised for around 7 – 10 days and usually no more than three injections to a structure over a year.
Research has examined whether cortisone injections are beneficial or harmful to the patient especially with regards to tendons. What has been shown is that cortisone injections are better than a placebo injection in the short-term,(2–6 weeks) for pain relief. However 3 months upwards they perform worse, and may actually be detrimental to the tendon or cartilage, when compared to either a placebo injection or conservative treatment. (see table 1)
As highlighted in table 1 they may be of short term benefit but rarely if ever do they offer a long term solution. Below is a table highlighting the potential benefits of cortisone injections for various conditions. As can be seen there is no guarantee that they will successful.
PRP injections, the new-ish kid on the block.
Platelet -rich -plasma is a technique where a sample of your own blood is taken and centrifuged, really fast spinning, to isolate the platelets, proteins and growth factors in a small volume of plasma. These components that are isolated play a role in the healing and regeneration of soft tissue. Over the past few years there has been growing use and studies of using PRP injections in tendon and ligament injuries.
Interestingly enough its these very same blood products that are increased with resistance based exercise !
Is PRP effective in the treatment of soft tissue injuries ?
A recent review published in 2019, (ref 1), identified that PRP was no more effective in the treatment of acute muscle injuries than the standard care already recommended.
When used to treat persistent of long term tendon related issues there did appear to be a small benefit but whether this was a clinically relevant improvement was of some debate. However other studies have shown PRP to be more beneficial long term that cortisone in the treatment of tennis elbow, which can probably be applied to most tendon related issues.
High Volume injections for achilles tendons.
High volume injection for persistent tendinopathy of mid portion achilles tendinopathy involves injection of saline plus corticosteroid between the anterior aspect of the Achilles tendon and Kager’s fat pad . It is though that this volume of saline creates a local mechanical effects due to increased pressure of the saline occupying the space. This in turn results in the small nerves that are possibly sensitised and causing the pain to be “shut down” and stop the pain.
Prolotherapy or dextrose injections.
Prolotherapy is a technique that involves the injection of a dextrose solution and is typically used in the treatment of chronic painful musculoskeletal conditions. The theory is that the dextrose solution provides an irritant effect causing the cells to and thought to promote inflammation and trigger the tissues repair process.
A small number of clinical studies have evaluated the effectiveness of prolotherapy in patients with tendinopathy and have shown positive results. However these studies have highlighted that it is best used as a second line of treatment or as an addition to more conservative based treatments.
When should you consider an injection ?
Injections have a place for some individuals without a doubt . I’ve resorted to them a couple of times to kick start the healing process in a shoulder and knee that wasn’t responding to physiotherapy as i had hoped.
Certainly in more stubborn cases of tendon or ligament pain that aren’t responding to treatment, or where pain is impacting the ability to rehab the troublesome area effectively, injection based therapy could be considered. However it should be seen as an adjunct to that treatment but should not be seen as a replacement.
The decision to get an injection is always best discussed with your Doctor.
Essentially PRP, Prolotherapy and HVI are all trying to create the same response as we get with exercise, that being a mechanical response that stimulates our own natural healing response. They may get the ball rolling quicker so to speak if you aren’t responding to conservative or more conventional treatments and may be useful in more persistent stubborn cases.
Regardless of injection type it is not a magic bullet solution, it may however be part of the solution. Following injection therapy the tissue still has to get stronger and fitter to cope with the stresses imposed upon it otherwise you’ll be back to where you started.
The best course of action is start with simple strategies to ease the pain, if this is not successful an injection may be warranted. Then adopt an exercise based rehab to build the tissue back up , prevent recurrence and reduce the pain further.
I hope that helps you understand a little about injections.