As an MSK practitioner and sonographer with an invested interest in MSK ultrasound and MSK ultrasound training, this article is naturally biased! Here are my top 10 reasons (in no particular order) for using ultrasound in your practice, and why I feel every clinician working in MSK medicine should become competent in ultrasound scanning.
1. You can scan the other side... it’s quick and doesn’t cost anymore!
It is well known that significant anatomical variability exists between individuals, and asymptomatic pathology is not uncommon in musculoskeletal medicine. For example, Minagawa et al. (2013) revealed that clients in their 50’s had an equal number of symptomatic rotator cuff tears as asymptomatic tears. Milgrom et al. (1995) and Frost et al. (1999) also found similar frequencies in symptomatic and asymptomatic age matched controls. Similarly, rotator cuff calcific deposits have been found in up to 33% of symptomatic subjects (Sansone et al., 2016). But it doesn’t stop at the shoulder, asymptomatic structural changes on ultrasound have been found in the patella tendon in 22% of elite athletes (Cook et al., 1998). More specifically, in 25% of basketball players (Mjor & Elms, 2002), 10% of fencers (Giombini et al., 2011), and 26% of volleyball players (Malliaris et al., 2006). This has also been found in the Achilles tendon (Giombini et al., 2011).
Figure 1: A large calcific deposit in the asymptomatic shoulder of a 54 year old recreational tennis player
Being able to scan the other side and combining the clinical findings with the ultrasound images allows the clinician to help ascertain whether structural change is relevant to the client’s clinical presentation and pain. In private practice in London, a one-part MRI costs anything from £200-£800, so scanning the other side is cost prohibitive. In the National Heath Service (NHS) there is simply not the available resources to scan the asymptomatic side for comparison. As a result, clinical decisions, potentially even operations, are being carried out when they are not required. It takes minutes to carry out an ultrasound scan of the asymptomatic side to gain a comparative view. This can give the clinician valuable information to help determine the relationship between structural findings and the potential pain source. One must also note that bilateral abnormalities occur even in the presence of unilateral symptoms (Yamaguchi et al., 2006; Levin et al., 2005).
2. Clients like ultrasound!
Adding an ultrasound scan to your clinical examination results in higher client satisfaction in that episode of care (Middleton et al., 2004).
Ultrasound is well tolerated by all, unlike MRI, and there are very few contraindications. You can scan clients with metal work and pacemakers, and there are no issues with claustrophobia and ionising radiation. It is a very safe imaging modality.
3.Ultrasound has excellent diagnostic accuracy
For most tendon complaints, ultrasound is equal to, or better than, MRI in its diagnostic capability (Figure 2 & 3). Ultrasound demonstrates superior spatial resolution to MRI and so can obtain greater information about the intrinsic structure of a tendon.
Figure 2: Sensitivity and specificity of ultrasound in the upper limb tendons
Figure 3: Sensitivity and specificity of ultrasound in the lower limb tendons
A bit more about the shoulder….
In the shoulder, it is advocated that unless there is trauma, suspicion of a labral or capsular defect or red flags, an ultrasound is the imaging modality of choice (Nazarian et al., 2013) (Figure 2). This is likely to account for approximately 80% of all shoulder clients. I would suggest at present there is a significant over-reliance on MRI.
There are several reasons for this, including culture, clinician habit, a lack of trained ultrasonographers, financial reasons in private practice and a lack of knowledge with regards to the application and accuracy of ultrasound. This is likely to see a slow but steady shift over the coming years as more and more clinicians begin to carry out the scans themselves in clinic, and departments appreciate the significant financial savings that can be made, the reduction in number of appointments required in an episode of care and the subsequent reduction in waiting times.
There are exceptions where MRI is the imaging modality of choice. Certain tendons are challenging to scan due to their anatomical position and require greater skill from the operator. The proximal hamstring, distal biceps, psoas tendon insertion, indirect tendon of the rectus femoris and the popliteus tendon are all challenging to scan. MRI is often used when pathology is suspected in these structures as it provides greater diagnostic information.
Don’t under estimate a negative scan!
We have discussed the diagnostic accuracy of ultrasound but lets not under estimate the role of a negative scan in the clinical setting. The negative predictive value of ultrasound can be very high. The plantarfascia, Achilles and patella tendon are good examples where a normal scan makes it highly unlikely it is the source of pain. This can be very reassuring for the client and instigate the clinician to look else where for a diagnosis.
Figure 5: Shows a longitudinal section of a normal Achilles tendon, which makes it very unlikely that this is the source of pain.
4. Dynamic scanning - ultrasound is the only imaging modality where you can observe the anatomy during movement.
Ultrasound allows us to appreciate the relationship of one anatomical structure on another and visualise in detail how one anatomical structure moves on another, be it when we stress a joint, a ligament or even contract a muscle. Ultrasound is the only imaging modality that allows us to gain this dynamic information. Furthermore, we are not limited by which plane we can scan in, unlike MRI. For example we can follow a muscle from its insertion to its origin to image the anatomy in fine detail. Ultrasound is the only imaging modality of choice for some conditions. A patient may notice pain, clicking, a mass, or other symptoms that occur only when they makes specific movements.
The client may only notice pain, clicking or a mass when they are moved into a certain position e.g. loose bodies in joints.
Ultrasound is a natural extension of the clinical examination. The dynamic nature of ultrasound makes it the ideal imaging modality for many conditions.
Here are a few examples:
Figure 6: Dynamic assessment for ITB friction syndrome – image shows the ITB in transverse section as it passes over the lateral condyle of the femur with knee flexion from 0-30°.
Figure 7: Dynamic impingement test of the shoulder – with the probe positioned on the suprapinatus tendon in longitudinal section – the client abducts their arm from 0-60 degrees and the bursa is visualised as it passes under the acromion
Ultrasound can show in real time the dynamic changes in other conditions such as ulnar nerve or peroneal tendon subluxation and laxity in a joint on dynamic ligament testing e.g. whilst performing a valgus stress test on the knee to assess for MCL laxity.
Figure 8: Ultrasound is an extension of your clinical examination
Ultimately, dynamic ultrasound scans compliment the clinical assessment, challenge your clinical reasoning and add valuable information that would otherwise not be gained.
5. You can scan and inject in one appointment – ‘a one-stop clinic’
Having the ability to carry out a clinical assessment, an ultrasound scan and if required, a guided injection in one appointment (i.e. ‘a one-stop clinic’) has obvious benefits to the client. Ultrasound is a unique imaging modality that can be used for diagnostic purposes and for guided interventions.
The accuracy of unguided/landmark injections is generally poor. We know from 14% to 71% of injections done ‘blind’/landmark guided (without image guidance) miss their target and the use of US guidance significantly decreases failure rates to about 5% (Finnoff et al., 2014).
Ultrasound allows you to guide a needle into a joint or tendon sheath with excellent accuracy. There is evidence to show that guided injections are more efficacious than unguided injections (Aly et al., 2014, Soh et al., 2011). But aside from the accuracy and efficacious debate there are also many other potential benefits. These include the diagnostic capabilities, when you know the injection was accurately placed it is unlikely to avoid unnecessary repeat injections in case the first one 'missed'. Accurate injections may reduce post injection pain, avoid side effects such as depigmentation and fat atrophy and reduce the chances of injecting structures where we know the injectable has known detrimental effects e.g. steroid into tendons.
Figure 6: An ultrasound guided sub-acromial bursal injection in a 32 year old with chronic shoulder pain
Ultrasound is the only imaging modality that can differentiate between a fluid-filled mass and a solid mass. MRI often indicates a cyst or other fluid collections are amenable to aspiration for example, ganglion cysts, Baker’s cysts, paralabral cysts and meniscal cysts. Ultrasound shows these fluid collections in more detail and can identify synovial folds, debris, and vascularised synovial tissue that is may indicate the lesion is not appropriate or amenable to aspiration. Sonographic pressure can give valuable information regarding the compressibility and consistency of the lesion. This has significant benefits when considering whether or not to aspirate and so can potentially avoids unnecessary pain and discomfort to a client.
The potential applications of ultrasound-guided procedures are expanding rapidly. Procedures such as transverse ligament release for carpel tunnel decompression, A1 pulley release for trigger finger, plantaris release for medial Achilles pain and tendon stripping techniques for chronic patella and Achilles' tendon pain are starting to substitute certain operations.
6. It's portable and getting more portable!
Ultrasound machines have come down in size and in price! The image quality has improved significantly allowing us to visualise the tissue in finer detail. Point of care ultrasound (POCUS) is a rapidly developing area and machines are now being used in a variety of clinical environments including pitch side, Accident & Emergency and community settings.
Figure 7: Ultrasound machines have reduced in size whilst maintaining their processing power and image quality
7. Helps to find the painful structure, not just the abnormal structure!
Most patients attend a clinic because they are in pain. Identifying structural abnormalities is part of the clinician’s role, but identifying the pain producing structure is often more of a challenge. However identifying it is essential if guided intervention is being considered. Placing the ultrasound probe directly over the area of the pain and palpating the structure at the same time, or pressing with the probe onto a specific structure (known as ‘sonographic palpation’) increases the chances of detecting the painful source. The mid-foot joints are a great example of this. There are so many joints in a very small space and often MRI identifies osteoarthritis in several of the joints. Using sonographic palpation, clinical palpation and color/power Doppler to identify any joint synovitis we are able to pin-point the exact joint that is causing the pain and increases the chances of a successful injection.
8. The use of color/power Doppler to identify blood flow
The wide spectrum of ‘normal’ anatomical variation between individuals and the often subtle anatomical abnormalities are an obvious challenge to identifying relevant clinical findings. Detecting hyperaemia on color and/or power Doppler on ultrasound can increase the clinician’s confidence that a finding on ultrasound is relevant to the client’s pain. This has been demonstrated in tendinopathy and synovitis. The use of ultrasound in the early detection of inflammatory arthritis has made a significant difference in the disease progression of many rheumatological patients. Ultrasound provides excellent resolution of small blood vessels, superior to contrast enhanced MRI. Color Doppler can also differentiate whether the blood flow is arterial or venous.
Figure 8: Hyperaemia (neovascularisation) in a distal patella tendinopathy of a 24 year old male basketball player. Greyscale changes on ultrasound on asymptomatic tendons are not uncommon, but hyperaemia on color/power Doppler increases the likelihood of the structure being the pain source.
Figure 9: The radiocarpal joint of a 55 year old male with rheumatoid arthritis complaining of severe wrist pain. The ultrasound scan revealed significant synovitis on color Doppler.
Doppler sonography is also useful in characterising superficial vascular malformations and soft-tissue masses. Some soft-tissue masses such as neuromas are quite hypoechoic and can simulate cysts on sonography, but the presence of internal Doppler flow can confirm their solid nature (Nazarian et al., 2008).
9. Ultrasound is operator-dependent and has a long learning curve!
Why is this in the top 10 reasons you may ask! If it was easy and only took a few weeks to master everyone would be using it. Once you have gained basic competency in MSK ultrasound imaging you have gained a valuable skill that will stand you apart from other clinicians, open up new career opportunities, and allow you to provide an even better service to your patients.
The reality is that learning ultrasound imaging is challenging, takes time and can be frustrating. It is first and foremost a motor skill and developing the probe skills and hand-eye coordination is essential to producing the clear images to make a diagnosis. It is like driving a car or learning to play a musical instrument.
Once you have mastered the skill then you must be able to interpret the images and determine how the scan findings fit into the clinical history, presentation and other imaging/test results. The final piece of the jigsaw is to use all the information you have gained to optimise the clients management.
10. Because it is great fun and makes you a better clinician!
It is a fun journey which significantly improves your:
But more importantly, it allows for an early and accurate diagnosis, which is essential for the implementation of a timely and effective treatment plan for your clients. It takes away much of the clinical guesswork and ultimately it is a journey well worth making!
If you would like further information or would like to start your ultrasound training please don’t hesitate to contact us at email@example.com
By Chris Myers