Ober's Test

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Purpose

The Ober's test evaluates a tight, contracted or inflamed Tensor Fasciae Latae (TFL) and Iliotibial band (ITB). There are 2 variants of the test:

The Ober’s test must not be confounded with Noble’s test and the Renne test, two other tests that are commonly used to detect iliotibial band syndromeThe Ober's test is performed to assess for tightness of the ITB and the TFL along the lateral aspect of the hip and thigh.

Clinically Relevant Anatomy

Anatomically, the ITB is a continuation of the tendinous portion of the Tensor Fascia Latae (TFL) muscle with some contributions from the gluteal muscles. TFL/ITB is a synergist of gluteus medius muscle in hip abduction.

Origin:

The TFL originates from:

• the anterior part of the external lip of iliac crest
• outer surface of anterior superior iliac spine and
• deep surface of fascia lata.

The Iliotibial band (ITB) or tract is a lateral thickening of the fascia lata in the thigh. Proximally it splits into superficial and deep layers, enclosing tensor fasciae latae and anchoring this muscle to the iliac crest. It also receives most of the tendon of gluteus maximus. The ITB is generally viewed as a band of dense fibrous connective tissue that passes over the lateral femoral epicondyle and attaches to Gerdy's tubercle on the anterolateral aspect of the tibia. 

The ITB originates from:

• the external lip of the anterior iliac crest
• anterior border of the ilium spine
• the outer surface of the anterior superior iliac spine

Insertion:

The TFL inserts into the ITB at the anterolateral thigh at the junction of proximal and middle thirds of the thigh.
The ITB expanses between the lateral aspect of the patella and biceps femoris, to insert into the Gerdy tubercle. For the stabilization of the knee, it helps to expanse the lateral collateral ligament and posterolateral joint capsule.
Gluteus medius, gluteus minimus, and upper fibres of the gluteus maximus are the primary synergistic muscles of the hip abductors.

TFL/ITB is a synergist of gluteus medius muscle in hip abductionAnatomically, the ITB is a continuation of the tendinous portion of the tensor fascia lata (TFL) muscle with some contributions from the gluteal muscles.

Technique

Test position:

• The patient should be in side-lying with the affected side up
• Bottom knee and hip should be flexed
• For consistency in testing, some suggest using top hand and arm to be placed under the flexed knee holding onto the side of the table. Note the angle of the hip and knee which should be near 90/90. This may allow for better reproduction for future testing

Test:

• Extend and Abduct the hip joint
• Slowly lower the leg toward the table -adduct hip- until motion is restricted
• Ensure that the hip does not internally rotate during the test and the pelvis must be stabilized to maintain position

Results:

The patient should be positioned on the side with the unaffected leg under his affected leg. He’ll need to slightly flex both the knee and hip in a 90° angle for stability. According to some articles, the patient can place his hand and arm under the flexed knee. While stabilizing the pelvis, the examiner can abduct and extend the upper affected leg allowing the iliotibial band to move posteriorly over the greater trochanter. Proximal hand or hip of the examiner as a fixation can avoid anterior tilting of the patient’s pelvis. The examiner slowly lowers the upper leg.

• If the ITB is normal, the leg will adduct and the patient won't experience any pain, in this case, the test is called negative.
• If the ITB is tight, the leg would remain in the abducted position and the patient would experience lateral knee pain, in this case, the test is called positive.
  
  
  • Ober’s test: The patient lies on the uninvolved side with hip and knee flexed in a 90-degree angle. The examiner placed the knee in a 5° flexion angle, fully abducts the lower extremity that needs to be tested, then allows the force of gravity to adduct the extremity until the hip cannot adduct any further. 
  • Modified Ober’s test: The patient is positioned on the side of the unaffected leg with the hip in neutral position and the knee in full extension.
    

Key Research

There is a limited number of studies to support the validity of this test.

A study by Reese et al. demonstrated a significant difference in ROM between testing with the affected knee flexed vs. extended, with the reliability of .90 and .91 respectively.

http://www.udel.edu/PT/PT%20Clinical%20Services/journalclub/sojc/04_05/mar05/inclinometerobers.pdf   

• Assessment of Stretching of the Iliotibial Tract With Ober and Modified Ober Tests: An Ultrasonographic Study

A study by Wang T-G et al. showed the ITB can be successfully stretched by the Ober and modified Ober tests, however, the modified Ober test was more effective for at producing greater hip adduction.

• Reliability of Measurements Obtained by Use of an Instrument Designed to Indirectly Measure Iliotibial Band Length

Modified Ober’s test and Ober’s test repeated measurement was shown to have good inter-rater reliability 0.73 and excellent intra-rater reliability 0.94 in participants with anterior knee pain

Resources

F. R. Ober:
The role of the iliotibial band and fascia lata as a factor in the causation of low-back disabilities and diabilities and sciatica.
Journal of Bone and Joint Surgery, Boston, 1936, 18: 105-110.

This test is also known as the Ober's Abduction Sign and Ober's sign

Gajdosik RL, Sandler MM, Marr HL Influence of knee positions and gender on the ober test for length of the iliotibial band Clinical Biomechanics

The Ober’s test with the knee extended and the knee flexed, limited hip adduction more than with the knee extended, yielded different results.

Clinical Bottom Line

If the patients have iliotibial band syndrome and there is a doubt about the diagnosis, MRI can help to confirm the diagnosis by giving additional information about patients who can be considered for surgery. MRI illustrates a thickened iliotibial band over the lateral femoral epicondyle and frequently detects a fluid collection deep into the iliotibial band.

References

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