Intraarticular Injections for the Treatment of Knee Osteoarthritis in Primary Care

Chronic knee pain is a common complaint in adults presenting to primary care. Osteoarthritis of the knee is a common finding. Initial treatments include acetaminophen and non-steroidal anti-inflammatory drugs (NSAID).

When the patient has failed other medical treatment, they can be offered IACI in primary care or orthopedic referral for HA injection or surgical intervention. Most patients do not present expecting a surgical referral. Should they be offered some relief through intraarticular injection of corticosteroids in primary care?

Comparison Between Corticosteroids and Hyaluronic Acid

The knee is the most commonly afflicted joint with osteoarthritis. It affects an estimated 46 million in the US and nearly half of all adults will develop symptomatic
knee OA by the age of 85.¹ These patients present with complaints of pain, stiffness, and immobility. The development of OA of the knee is a mechanical and inflammatory process that destroys both cartilage and bone.

The goal of therapy is pain relief and return to function as soon as possible. One mainstay of therapy is the use of intraarticular corticosteroid injections to provide relief of pain by arresting the inflammation and destruction of the intraarticular structures. The corticosteroid inhibits prostaglandin synthesis and controls the local inflammation by decreasing the activity of other destructive enzymes.² IACI remains the simplest and most cost-effective treatment of knee OA.

Hyaluronic acid intra-articular knee injections are widely used but primarily restricted to orthopedic surgeons. HA injections have a beneficial effect on OA of the knee. HA normalizes hyaluronan synthesis and inhibits proteoglycan degradation. The HA not only “lubricates” the joint but has an analgesic and anti-inflammatory effect.³

Discussion

There are many treatment options for OA of the knee, both non-surgical and surgical. Intraarticular injections offer a nonsurgical alternative and these studies show that IACI and HA give relief of symptoms and last an average of 2 or 3 months respectively.³ In a cost utilization study a total of 244,059 patients met the inclusion criteria and 35,935 of those patients (14.7%) had at least 1 HA injection in the 12 months preceding total knee arthroplasty (TKA). HA injections were responsible for 16.4% of all knee osteoarthritis-related payments, trailing only imaging studies expenses at 18.2%, plus HA injections accounted for 25.2% of treatment-specific payments, a rate that was higher than that of any other treatment. (see Table 1)³.

Total payments associated with HA injections in the study cohort amounted to $40,547,881 over the study period.³ The treatment-specific payments for IAC injections were only 18.2% compared to 25.2% for HA over the same period.³ They offer relief of symptoms and return of function for patients who are not candidates for surgical intervention.⁴

When discussing treatment options with our primary care patients with knee OA, we need to present the evidence for each option. By sharing this information, we can facilitate shared decision-making. We can then offer them IACI in primary care, or we can refer them to orthopedics for HA injection.⁵

Intraarticular Corticosteroid Injection

If the patient is interested in IACI, the preparation begins with knee radiographs to assess any obstacles and to help determine the correct approach.

Examine the knee and review the patient’s chart to rule out any absolute contraindications, such as septic joint or critically, low or dysfunctional platelets. Rule out any relative contraindications like regular NSAID use in the last 48 hours.

The patient should not have had a corticosteroid injection in that knee in the last month or oral steroids in the last 2 weeks, no recent fever, no cancer, no anemia (HBG less than 10 g/dL), or thrombocytopenia.⁶

Once the shared decision is made to move forward, obtain informed consent. Have the patient sit on the end of the exam table with their knee bent and relaxed. Choose an approach based on the path of least obstruction, mark the skin with a marker in an inverted triangle, using the inferior and lateral patella border as 2 legs of the “triangle” (See Photo).⁶

The knee is prepped with a skin disinfectant. One study recommends using the anterolateral because it causes less patient discomfort.7 Insert a 10cc syringe with a 25-gauge 1.5-inch needle into the intraarticular space. Then attempt aspiration by drawing back on the plunger. If you don’t get a return with bloody or purulent fluid, replace the empty syringe with another containing 4 cc of 1% lidocaine and 1 cc of triamcinolone acetonide (40 mg/ml).⁸ Inject the contents into the intraarticular space slowly. Then remove the needle and place a band-aid over the injection site.

Give the patient instructions to rest for the next 48 hours, use ice for any swelling, or return if any redness or fever occurs. It is a simple step-by-step method.⁹ If you are interested in becoming proficient in joint aspiration and injection, sign up for a procedure workshop at the next AAPA conference.¹⁰

Conclusion

Chronic knee pain is a common complaint in adults presenting to primary care. Osteoarthritis of the knee is a common finding. Initial treatments include acetaminophen and non-steroidal anti-inflammatory drugs. When the patient has failed other medical treatment, you can offer them intraarticular corticosteroids or an orthopedic referral for hyaluronic acid injection or arthroplasty.

Due to the expense of both HA injection and orthopedic referral,² it is proposed that initiation of treatment with IACI to the affected knee be done in primary care. If that treatment becomes ineffective then discuss referral to orthopedics for further treatment.⁵