LATERAL KNEE PAIN
Iliotibial band syndrome (ITBS)
A common source of lateral knee pain, ITBS is found particularly in runners, cyclists, and endurance athletes.17-19,36,37 The exact pathophysiology behind this diagnosis is debatable, but the most accepted etiology is inflammation generated from microtrauma to the soft tissues with inadequate healing time, resulting in persistent inflammation. ITBS is often associated with excessive overall running mileage, a sudden increase in mileage, or an abrupt change in training.18,37
Diagnosis. Patients often complain of persistent nontraumatic lateral knee pain that worsens with repetitive knee flexion (eg, running or cycling).17-19,37 A physical exam will often reveal pain over the lateral femoral condyle and a positive Noble’s test (see Figure 1, page 30). A positive Ober’s test (see Figure 2, page 32) is suggestive of ITBS, as well. The sensitivity and specificity of these tests are not well established, but in patients performing repetitive knee flexion activities with subjective lateral knee pain, pain over the lateral femoral condyle and a positive Ober’s and/or Noble’s test suggest an ITBS diagnosis.18 Imaging is not indicated initially, but MRI should be used in refractory cases to rule out other etiologies.17,19
Treatment. First-line therapy for ITBS is conservative,17-19,36,37 often involving a combination of techniques such as refraining from the activity that triggers the pain, NSAIDs, activity modification to reduce the strain over the ITB, myofascial release via foam rollers, and physical therapy focused on stretching the ITB, tensor fasciae latae, and gluteus medius while strengthening the gluteus medius and core muscles.17 No single program has been shown to be better than another.
Corticosteroid injections are second-line therapy and have been shown to improve pain compared with placebo up to two weeks postinjection.17,19 When symptoms persist for more than six months despite conservative treatment, surgical intervention may be indicated.18,19 Patients who experience temporary pain relief with corticosteroid injections often respond best to surgery.36
MEDIAL KNEE PAIN
Medial plica syndrome
Because of its anatomic location, the medial plica—which can be palpated in up to 84% of the population20—is susceptible to impingement by the medial femoral condyle or the patellofemoral joint. Trauma with repetitive knee movement leads to inflammation and thickening of the plica, resulting in medial plica syndrome.20,38 Initial inflammation may be triggered by blunt trauma, a sudden increase in activity, or transient synovitis.22
Diagnosis. Medial plica syndrome is a challenging diagnosis. Patients generally have nonspecific complaints of aching medial knee pain, locking, and catching similar to complaints of a medial meniscal injury.20
Evaluation should include the mediopatellar plica test, which is performed with the patient lying supine with the knee fully extended. Pressure is placed over the inferomedial patellofemoral joint, creating an impingement of the medial plica between the finger and the medial femoral condyle. Elimination or marked diminishing of pain with knee flexion to 90° is considered a positive test.21
A recent systematic review found this test to be more diagnostically accurate than an MRI (sensitivity of the test is 90% and specificity is 89%, vs 77% and 58%, respectively, for MRI) for detection of medial plica syndrome. Ultrasound is almost as accurate, with a sensitivity of 90% and specificity of 83%.39
Treatment of medial plica syndrome centers on physiotherapy and quadriceps strengthening,20 augmented with NSAIDs. Intra-articular corticosteroid injections are considered second-line treatment.20,22 An orthopedics referral is indicated to consider arthroscopic plica removal for refractory cases.20,22
Pes anserine bursitis
The anserine bursal complex, located approximately 5 cm distal to the medial joint line, is formed by the combined insertion of the sartorius, gracilis, and semitendinosus tendons,39 but the exact mechanism of pain is not well understood. Whether the pathophysiology is from an insertional tendonitis or overt bursitis is unknown, and no studies have focused on prevalence or risk factors. What is known is that overweight individuals and women with a wide pelvis seem to have a greater predilection and those with pes planus, diabetes, or knee osteoarthritis are at increased risk.23
Diagnosis. Medial knee pain reproduced on palpation of the anatomic site of insertion of the pes anserine tendon complex supports a diagnosis of pes anserine bursitis, with or without edema. Radiologic studies are not needed but may be helpful if significant bony pathology is suspected. Ultrasound, CT, and MRI are not recommended.23
Treatment. Resting the affected knee, cryotherapy, NSAIDs, and use of a pillow at night to relieve direct bursal pressure are recommended.33 Weight loss in obese patients, treatment of pes planus, and control of diabetes may be helpful, as well. Although the literature is limited and dated, corticosteroid injection has been found to reduce the pain and may be considered as second-line treatment.24-26
POSTERIOR KNEE PAIN
Popliteal (Baker’s) cyst
The popliteal fossa contains six of the numerous bursa of the knee; the bursa beneath the medial head of the gastrocnemius muscle and the semimembranosus tendon is most commonly involved in the formation of a popliteal cyst.40 It is postulated that increased intra-articular pressure forces fluid into the bursa, leading to expansion and pain. This can be idiopathic or secondary to internal derangement or trauma to the knee.41 Older age, a remote history of knee trauma, or a coexisting joint disease such as osteoarthritis, meniscal pathology, or rheumatoid arthritis are significant risk factors for popliteal cysts.27
Diagnosis. Most popliteal cysts are asymptomatic in adults and discovered incidentally after routine imaging to evaluate other knee pathology. However, symptomatic popliteal cysts present as a palpable mass in the popliteal fossa, resulting in pain and limited range of motion.
During the physical exam with the patient lying supine, a medial popliteal mass that is most prominent with the knee fully extended is common. A positive Foucher’s sign (the painful mass is palpated posteriorly in the popliteal fossa with the knee fully extended; pain is relieved and/or the mass reduced in size with knee flexion to 45°) suggests a diagnosis of popliteal cyst.27,28
Radiologic studies are generally not needed to diagnose a popliteal cyst. However, if diagnostic uncertainty remains after the history and physical exam, plain knee radiographs and ultrasound should be obtained. This combination provides complementary information and helps rule out a fracture, arthritis, and thrombosis as the cause of the pain.27 MRI is helpful if the diagnosis is still in doubt or if patients are suspected of having significant internal derangement leading to cyst formation. Arthrography or CT is generally not needed.27,41
Treatment. As popliteal cysts are often associated with other knee pathology, management of the underlying condition often leads to cyst regression. Keeping the knee in flexion can decrease the available space and assist in pain control in the acute phase.27 Cold packs and NSAIDs can also be used initially. Cyst aspiration and intra-articular corticosteroid injection have been shown to be effective for cysts that do not respond to this conservative approach.27 However, addressing and managing the underlying knee pathology (eg, osteoarthritis, meniscal pathology, or rheumatoid arthritis) will prevent popliteal cysts from recurring.
Continue for when the problem is painful knee effusion >>