Comprehensive Management Of Chronic Knee Pain
Knee pain is a very common complaint that can be debilitating when severe. A proper evaluation must begin with a thorough history and physical examination.
If the patient is not a surgical candidate, there are several conservative treatment options—such as physical therapy for retraining of proper mechanics, kinesiology taping to improve proprioception, acupuncture and chiropractic treatment—that may alleviate the patient’s symptoms (Figure 1).
Depending on the nature of the pain, a variety of analgesic medications may be prescribed, including anti-inflammatory drugs, membrane-stabilizing agents and in severe cases, opioid analgesics. Unfortunately, these medications may not significantly reduce the pain and their long-term compliance may be limited by untoward side effects. Additionally, many patients have intractable chronic pain after more invasive treatment options such as a total knee arthroplasty (TKA). Studies have reported that 20% of patients undergoing TKA have persistent postsurgical pain.1 These patients often present to the pain clinic frustrated by the failure of conservative and possible surgical interventions. Fortunately, depending on the pain generator, there is a wide array of interventional treatment options that can be implemented (Figure 2).
History and physical
Diagnostic workup (ultrasound, x-ray, MRI, NCS/EMG)
Possible surgical candidate?
If yes, consider early orthopedic referral
If no, consider conservative management
Manual therapy (PT, chiropractor/DME)
Analgesics (ibuprofen, NSAIDs)
Behavioral, psych (biofeedback, relaxation techniques)
Figure 1. Conservative treatment algorithm.
DME, durable medical equipment; EMG, electromyography; MRI, magnetic resonance imaging; NCS, nerve conduction study; NSAID, nonsteroidal anti-inflammatory drug; PT, physical therapy
Failed conservative treatment
Phase 1
Image-guided knee steroid/hyaluronic acid injection
Image-guided knee stem cell/PRP injections
Phase 2
Saphenous and lateral femoral cutaneous nerve block; RFA if successful
Femoral nerve block, RFA if successful
Lumbar sympathetic plexus block (L2, L3); RFA if successful
Genicular nerve block; RFA if successful
Lumbar SCS trial; permanent implant if successful
PNS trial; permanent implant if successful
Phase 3
Refer back to orthopedic surgeon for reevaluation
Figure 2. Nonsurgical knee pain.
PNS, peripheral nerve stimulation; PRP, platelet-rich plasma; RFA, radiofrequency ablation; SCS, spinal cord stimulation
Evaluation
The primary nerve innervation of the knee arises anteriorly from the femoral nerve and posteriorly from the sciatic nerve. These nerves give rise to a number of smaller branches that provide sensation to a variety of specific regions around the knee (Figure 3). The saphenous nerve branches from the femoral nerve and provides sensation over the distal aspect of the medial two-thirds of the thigh. The lateral one-third of the distal thigh is supplied by the superficial femoral cutaneous nerve. The superior medial, inferior medial, and middle genicular nerves arise from the tibial nerve—the medial division of the sciatic nerve. The superior lateral, inferior lateral, and recurrent tibial genicular nerves arise from the common peroneal nerve—the lateral division of the sciatic nerve.2
Figure 3. Innervation of the knee.
A thorough history and physical can aid the clinician in developing a focused differential diagnosis and effectively managing the patient with knee pain. Specific location of the pain, cause of the pain, duration of symptoms, alleviating and/or exacerbating factors, associated ipsilateral back and/or hip pain, and the outcome of any previous interventions should be investigated. The physical exam should always begin with inspection of the knee to assess for signs of gross deformity, edema, or cellulitis. Provocative exam maneuvers such as the valgus/varus stress, anterior/posterior drawer, Lachman’s test, McMurray’s test, and the patellar grind test may provide a great deal of information whether positive or negative. If bony etiology is suspected, imaging should include an x-ray of the knee. However, if soft tissue pathology is suspected, an ultrasound or a magnetic resonance imaging scan of the knee may be more appropriate. Furthermore, given that it is common for knee pain to be a manifestation of referred back or hip pain, imaging of these regions as well as electrodiagnostic studies may be appropriate. Electrodiagnostic studies also should be completed if there is any concern for neuropathy. Correlating the patient’s symptoms and physical exam findings with abnormal diagnostic test results can help to condense the differential diagnosis and aid in tailoring a treatment plan.3
Current Evidence for Interventional Therapy
There is a growing body of literature that supports the use of a variety of interventional procedures in the management of knee pain. Raynauld et al demonstrated improved pain relief with intraarticular steroid injection versus saline over a 2-year period with repeated injections every 3 months.4 Neustadt et al showed that intraarticular hyaluronic acid injections brought about some symptomatic pain relief compared with placebo.5 A study by Choi et al revealed that radiofrequency ablation of the superior medial, superior lateral, and inferior medial genicular nerves produced significant pain relief in patients with knee osteoarthritis.6 Wakitani et al demonstrated repair of articular cartilage defects following intraarticular injection of human autologous mesenchymal stem cells.7
Ultrasound Versus Fluoroscopically Guided Injections
Figure 4. Knee ultrasound.
Arrowheads, medial collateral ligament
Medial meniscus
Distal hip adductor muscles can be seen at the top of the image.
Incorrect placement of injectate within the knee can lead to increased pain and decreased therapeutic benefit. The literature suggests that there is an increased rate of successful intraarticular placement using image guidance compared with blind injections (ie, using surface anatomic landmarks). In light of this, ultrasound and fluoroscopy are both frequently used to perform interventional procedures for knee pain. Each has advantages and disadvantages with respect to a given procedure. Fluoroscopy provides better visualization of the knee joint, which improves the likelihood of successful intraarticular injection. Given the relatively radiopaque appearance of periosteum and hardware from prior TKA, this is ideal for genicular nerve blocks. However, the patient is subjected to radiation exposure with its usage. Ultrasound allows for better visualization of soft tissue structures, which can dramatically improve the success rate of peripheral nerve and bursa injections in this region (Figure 4). The normal characteristic appearance of various anatomic structures in the region of the knee aid the interventionalist in target localization. Given the real-time dynamic nature of this imaging modality, the needle tip and/or injectate can be easily visualized for both intra- and extraarticular injections to confirm accurate location.8,9 For ease of access into the intraarticular joint space, we recommend performing procedures with the patient in the supine position with the knee maximally flexed to approximately 135 degrees. It is important to note that ultrasound is user-dependent, which makes for more variable results.
Interventional Procedures
The following is a list of interventional procedures that are commonly performed in the treatment of chronic knee pain:
Intraarticular knee injections: steroids, hyaluronic acid, traumeel, platelet-rich plasma (PRP), and mesenchymal stem cells (Figure 5).
Extraarticular knee injections: steroids, traumeel, PRP, and mesenchymal stem cells.
Trigger-point injections.
Peripheral nerve blocks: saphenous, superficial femoral cutaneous, genicular nerves (Figure 6).
Radiofrequency ablation: saphenous, superficial femoral cutaneous, genicular nerves.
Lumbar sympathetic plexus block (typically at L2 and/or L3 level).
Peripheral nerve stimulation: saphenous, superficial femoral cutaneous.
Lumbar spinal cord stimulation: treatment of last resort.
Figure 5. Mesenchymal stem cells.
Regenerative therapy can include platelet-rich plasma and stem cells. Mesenchymal stem cells may be procured from autograft bone marrow and
image
Figure 6. Peripheral nerve stimulation.
The patient is a 19-year-old female collegiate softball player who failed multiple orthopedic knee surgeries and was unable to participate in athletic activities. Following placement of peripheral field stimulation of the knee, she was able to return to play.
Courtesy of Dr. William S. Rosenberg, Center for the Relief of
References
Beswick AD, Wylde V, Gooberman-Hill R, et al. What proportion of patients report long-term pain after total hip or knee replacement for osteoarthritis? A systematic review of prospective studies in unselected patients. BMJ Open. 2012;2(1).
Jacobson JA. Introduction. In: Jacobson JA, ed. Fundamentals of Musculoskeletal Ultrasound. Philadelphia, PA: Saunders; 2007:1-14.
Jacobson JA. Knee ultrasound. In: Jacobson JA, ed. Fundamentals of Musculoskeletal Ultrasound. Philadelphia, PA: Saunders; 2007:224-263.
Raynauld JP, Buckland-Wright C, Ward R, et al. Safety and efficacy of long-term intraarticular steroid injections in osteoarthritis of the knee. Arthritis Rheum. 2003;48:370-377.
Neustadt D, Caldwell J, Bell M, et al. Clinical effects of intraarticular injection of high molecular weight hyaluronan (Orthovisc) in osteoarthritis of the knee: a randomized, controlled, multicenter trial. J Rheum. 2005;32:1928-1936.
Choi WJ, Hwang SJ, Song JG, et al. Radiofrequency treatment relieves chronic knee osteoarthritis pain: a double-blind randomized controlled trial. Pain. 2011;152:481-487.
Wakitani S, Imoto K, Yamamoto T, et al. Human autologous culture expanded bone marrow mesenchymal cell transplantation for repair of cartilage defects in osteoarthritic knees. J Osteo Res Soc Inter. 2002;10:199-206.
Waldman SD. Pain Management. Philadelphia, PA: Saunders; 2011.
Hurdle M-FB. Ultrasound-guided knee injections. In: Narouze SN, ed. Atlas of Ultrasound-Guided Procedures in Interventional Pain Management. New York, NY: Springer; 2011:331-335
BY: Tory McJunkin, MD
Co-founder
Arizona Pain Specialists
Scottsdale, Arizona
Paul Lynch, MD
Co-founder
Arizona Pain Specialists
Scottsdale, Arizona
Jarron Tilghman, MD
Physical Medicine and Rehabilitation Physician
Rockhill Orthopaedic Specialists
Kansas City, Missouri
Patrick Hogan, DO
Anesthesiologist, interventional pain physician
Arizona Pain Specialists
North Phoenix, Arizona
Adam Wuollet, MD
Anesthesiologist, interventional pain physician
Arizona Pain Specialists
Phoenix, Arizona
Edward Swing, PhD
Research Director
Arizona Pain Specialists Scottsdale, Arizona