Research Review By Dr. Shawn Thistle©

Date Posted:

March 2010

Review Title:

Musculoskeletal Injections: Practical Knowledge

Papers Reviewed:

  1. Wittich CM, Ficalora RD, Mason TG & Beckman TJ. Musculoskeletal injection. Mayo Clinic Proceedings 2009; 84(9): 831-837.
  2. Stephens MB, Beutler AI & O’Connor FG. Musculoskeletal injections: A review of the evidence. American Family Physician 2008; 78(8): 971-976.

Background Information:

As professionals who deal with musculoskeletal pain daily, we are often confronted by patients asking: “Should I get an injection for this pain? Will it help? Are injections safe?” These questions raise a number of issues that we are often not equipped to deal with.

Further, injections are seemingly offered as a front line treatment in most medical offices, often before manual or more conservative therapies, with or without consideration of the evidence. Personally, I don’t recall receiving any lectures on this topic during my education, but it stands to reason that we should be informed on this intervention. That is the purpose of this review, which integrates information from two recently published papers (see above).

Summary:

Injections can be a valuable tool in the treatment of many musculoskeletal problems and are typically directed into a joint (intra-articular), into structures around a joint (peri-articular), or into painful soft tissues. Injections can also serve a diagnostic purpose by identifying pain-generating structures (if pain is relieved upon injection, then the right structure has been identified/diagnosed).

Other common clinical goals of injection include:
  • reducing inflammation
  • providing pain relief
  • allowing rehabilitation exercise to be performed
  • allowing return to play/competition
Patients will often (and should) experience immediate relief if the injection is made into the right structure. Afterwards, it is not uncommon to experience a transient increase in pain before the longer lasting pain relief takes effect – this should be communicated to all patients.

As with any intervention, the key questions surrounding injections that must be asked are: Which patients are appropriate candidates? What should be injected? Are there significant risks of injection? How should the injection be performed? Since injections are outside our scope of practice, we will focus here on practical knowledge about injections so that we may effectively communicate with our patients on this topic.

What is actually injected?

Musculoskeletal injections normally involve a combination of local anesthetics (to provide immediate pain relief) and corticosteroids (to reduce inflammation and provide longer term pain relief). If a local analgesic is included, it can serve to confirm the accuracy of the injection (as mentioned, if the patient’s pain is reduced immediately, it was injected into the correct structure). Local anesthetics most commonly used include bupivacaine (more commonly used for trigger points) and lidocaine (more commonly used for bursae and joint injections).

The primary corticosteroids that are used include: betamethasone sodium phosphate/acetate, methylprednisone and triamcinoclone hexacetonide. Corticosteroids have many different mechanisms of action including:
  • reducing synovial blood flow
  • lowering local leukocyte and inflammatory modulator response
  • altering local collagen synthesis
The duration of action of corticosteroids depends primarily on their solubility, which is what differentiates the above listed steroids. Longer-acting steroids do carry a slightly higher risk of tissue atrophy and tendon rupture but this is minimal (1).

Can repeated injections be performed?

Most data in this area comes from studies on patients with rheumatoid arthritis. Overall, they indicate that repeated injections are safe. The recommended interval between injections is 3 months, but this should be guided by response to previous injections, disease state, patient preference, and clinical judgment.

Contraindications to Injection:
  • broken skin at the injection site
  • skin infection/cellulitis at injection site
  • known sensitivity to the intra-articular agent
  • joint prosthesis (relative contraindication - consult with orthopedic surgeon)
  • osteochondral/intra-articular fracture
  • severe joint destruction
  • unstable coagulopathy
Potential Adverse Reactions to Injections (and % incidence approximation where known):
  • overall, adverse reactions to the medications that are injected are rare
  • intra-articular injection of corticosteroids DOES NOT increase the progression of osteoarthritis
  • post-injection inflammation may occur, mimicking septic arthritis
  • septic arthritis itself as a result of injection is very rare (0.03% of cases)
  • there is a risk or hyperglycemia in patients with diabetes – this is considered relatively small, but should be discussed with diabetic patients by the physician performing the injection
  • adrenal suppression may occur, but typically lasts less than 2 weeks
  • the risk of hemarthrosis, even in those on anticoagulants such as warfarin, is small (even though this is normally considered a contraindication)
  • Other complications: skin atrophy (~2.4%); skin depigmentation (~0.8%); post-injection flare (2-10%); vaso-vagal reaction (10-20%); localized erythema/warmth/hypersensitivity (~0.7%); facial flushing (~0.6%); pericapsular calcification (up to ~40%!)
Which conditions are amenable to injections?

There are some specific ailments that respond well to injections, and also some general types of conditions. It should come as no surprise that, as with most musculoskeletal treatment options, the evidence is varied around the use of injections.

That being said, injections are generally considered a very effective treatment for de Quervain’s tenosynovitis – deemed more effective than NSAIDs, splinting, or a combination of the two (2). Injections are also very effective for bursitis, with the majority of this literature involving trochanteric bursitis (more recently termed Greater Trochanter Pain Syndrome – see reference 3 below) and the pes anserine bursa.

For trochanteric bursitis, injection can be considered a front line treatment due to its efficacy and safety in this region. Other conditions that may warrant treatment via injection include: arthritis (both inflammatory and non-inflammatory), bursitis in various locations,

Baker’s cysts, epichondylalgia (recalcitrant tennis elbow or extensor wad tendinosis) and tenosynovitis in locations other than the posterior outcropping muscles of the thumb (which was already mentioned above – de Quevain’s).

A note on Carpal Tunnel Syndrome (CTS):

Injections are commonly employed for CTS, but the literature as a whole is inconclusive as to the efficacy of this intervention (this can be said for numerous interventions for CTS!). If beneficial, the effects of injections for CTS tend not to last beyond one month.

Longer-term studies indicate that patients who fail to respond to early bracing or oral anti-inflammatory medication have similar outcomes at one year with corticosteroid injection or surgery (4).

A note on Knee Osteoarthritis:

There is a Cochrane Collaboration review on injections for knee OA (5) – aggregate results suggest that injection is more effective than placebo, hyaluronudate, or joint lavage (via arthroscopy) for short-term pain relief, however evidence for lasting functional improvement is lacking. Injection may be an option in conjunction with other conservative interventions, or if clinical progress is not achieved.

A note on Subacromial Impingement:

Subacromial pain/impingement is very common, and injections are often proposed to aid patients in performing their rehabilitation, or for pain relief. A Cochrane Review (6) suggests that injection provides no additional benefit over NSAIDs, so conservative treatment remains the front line approach.

Clinical Application & Conclusions:

We should be conversant in injection therapy, even if we cannot provide it. Since we are often the ones providing treatment to these patients before they are injected, they often seek our opinion.

Injections are generally safe and carry only minor risks of side-effects. Of course, these risks and the efficacy of the injection is operator dependent to some degree (but what isn’t in manual medicine?). When applied correctly, they can be very effective for a number of conditions including:
  • arthritis – both inflammatory and non-inflammatory (particularly OA in the knee)
  • bursitis – various locations (especially greater trochanter)
  • tenosynovitis – various locations (especially de Quervain)
  • carpal tunnel syndrome in some cases

Additional References:

  1. Nichols AW. Complications associated with the use of corticosteroids in the treatment of athletic injuries. Clin J Sport Med 2005; 15(5): 370-375.
  2. Richie CA & Briner WW. Corticosteroid injection for treatment of de Quervain’s tenosynovitis: A pooled quantitative literature evaluation. J Am Board Fam Pract 2003; 16(2): 102-106.
  3. Segal NA et al. Greater Trochanteric Pain Syndrome: Epidemiology and associated factors. Arch Phys Med Rehabil 2007; 88: 988-992.
  4. Ly-Pen D et al. Surgical decompression versus local steroid injection in carpal tunnel syndrome: a one-year, prospective, randomized, open, controlled clinical trial. Arthritis Rheum 2005; 52(2): 612.619.
  5. Bellamy N et al. Intraarticular corticosteroid for treatment of osteoarthritis of the knee [update of Cochrane Database Systematic Review 2005; (2):CD005328.]. Cochrane Database Syst Rev 2006; (2):CD005328.
  6. Buchbinder R, Green S, Youd JM. Corticosteroid injections for shoulder pain. Cochrane Database Syst Rev 2003; (1):CD004016.