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Knee pain is one of the most common problems encountered by recreational and competitive athletes. Pain over the lateral aspect of the knee can be the result of intra or extra articular conditions. The purpose of this clinical suggestion is to present the modification of a traditional clinical test to aide in the differential diagnosis of lateral knee pain. This method has not been described elsewhere and anecdotally has been helpful in the evaluation of patients with lateral knee pain.
Functional limitations due to knee pain are among the most common problems encountered by physically active individuals. For healthcare professionals, a thorough history and physical exam will often enable accurate medical diagnosis. In some cases, however, differentiation among multiple pathologies is difficult.
One area in which differential diagnosis can be difficult is in determining the source of lateral knee pain in the active individual. For individuals experiencing lateral knee pain as a result of high volume training (e.g., running, biking), patellofemoral syndrome (PFS) and iliotibial band syndrome (ITBS) are common. In addition to these common overuse conditions, a myriad of other possibilities should be considered (Table 1).
To narrow down the list of possibilities, special tests are commonly utilized. For the diagnoses listed in Table 1, numerous special tests exist to confirm these conditions. Many of these tests, although stated for a specific pathology, have not been proven to yield satisfactory sensitivity and specificity.1,2 Apley's compression and McMurray tests, advocated in the evaluation for a meniscus injury,3,4 will often yield a pain response in individuals with PFS or ITBS. To evaluate extra-articular lateral knee pain the Noble compression test3 and Ober test3,5 are commonly recommended for the differential diagnosis of ITBS. The Noble compression test is begun with the patient supine and the knee flexed to 90 degrees. The clinician applies and maintains pressure to the lateral femoral epicondyle while extending the knee. A positive test is indicated if the patient complains of pain over the lateral femoral epicondyle at approximately 30 degrees of flexion, the approximate point at which the iliotibial band moves over the lateral femoral epicondyle.
The Ober test is performed by positioning the patient on their side with the extremity being tested facing upward. The clinician flexes the knee to 90 degrees and abducts and extends the hip to place the thigh in line with the trunk. From this starting position the clinician allows the thigh to adduct as far as possible. The “modified Ober test” is performed in the same manner as the original Ober test but the knee is fully extended at the start of the test and knee extension is maintained as the lower extremity is allowed to drop into adduction. The Ober test, while assessing for flexibility, does not frequently reproduce the patient's symptoms.
While the iliotibial tract (ITT) insertion is often listed as localized to the lateral tubercle of the tibia (Gerdy's tubercle),4,6 a recent anatomical study of the anatomy of the ITT has demonstrated a complex network of distal insertions to various structures about the knee joint.7 In addition to the insertion at Gerdy's tubercle, the ITT also has insertions at the linea aspera, lateral epicondyle, lateral patella, as well as a broad capsular-osseous insertion.7
In many patients with subacute or infrequent symptoms, these two tests may be of marginal benefit in reproducing patient symptoms. Since the onset of symptoms experienced during running may not present within the early stages of lower-level activity, a movement placing more stress on the implicated tissue has proven helpful.
In order to better localize iliotibial band related pain from other conditions about the lateral knee, is suggested combining the Ober's and Noble compression test into a singular special test. Begin by taking the patient into the Ober's position with the knee flexed to 90 degrees. With the knee flexed to 90 the clinician should passively extend and flex the knee, while applying direct pressure over the lateral femoral epicondyle, monitoring the patient for a pain response.(Figure 1)
If this combination does not reproduce the patient's symptoms some modifications can be added to further strain the iliotibial band while moving the knee. Testing is progressed from passive extension and flexion of the knee to active flexion and extension of the knee. Evaluation through an arc of motion is supported by Orchard et al8 who reported that iliotibial band impingement, at the lateral femoral epicondyle, occurred at different angles of knee flexion. Furthermore, the addition of a medially or laterally directed patellar glide during passive or active flexion and extension of the knee may further impact symptom reproduction and localization.(Figure 2) Medial patellar glide commonly results in an increase of symptoms while application of lateral patellar glide more commonly reduces the patients symptoms. Application of internal rotation of the tibia while moving from flexion to extension may also aide in symptom reproduction.(Figure 3) When the side-lying technique does not adequately reproduce the patient's symptoms the same test movement can be performed in weight bearing, either partially unloaded (Figure 4) or with full weight acceptance. The movement pattern in standing is similar to a drop-step or “corkscrew” lunge with the uninvolved leg passing behind the involved leg. Caution is recommended if performing this movement in full weight bearing due to the increased load placed on the lateral compartment of the knee and the potential for adversely impacting intra-articular pathology.
As with many special tests, a key component is accurate reproduction of the patient's symptoms. Not only has this testing sequence been helpful for differentiating iliotibial band pain but also for reproduction and localization of lateral patellofemoral joint pain.
Critical review of clinical tests combined with advancing knowledge of anatomy and orthopedic pathology may lend itself to further modifications of currently accepted physical examination techniques. Clinical research would be helpful to further substantiate the aforementioned techniques along with other orthopedic special tests and their modifications.
The author would like to thank Hospital Corpsman First Class (HM1) Michael Duff for his assistance with photography and manuscript preparation.