Thomas Test (or as it called Hugh Owen Thomas well leg raising test) is used to measure the flexibility of the hip flexor muscles.
It’s used to test for hip flexion contracture and psoas syndrome (Iliopsoas Tightness), which is more common in runners, dancers, and gymnasts with symptoms of hip “stiffness” and “clicking” feeling when flexing at the waist.
The original Thomas test was designed to test the flexibility of the iliopsoas complex but has since been modified and expanded to assess a number of other soft tissue structures.
The original thomas test involves positioning the patient in supine, with one knee being held to the chest at the point where the lumbar spine is felt to flex. The clinician assesses whether the thigh of the extended leg maintains full contact with the surface of the bed.
The patient is supine. The unaffected, contralateral leg is flexed at the hip until the lumbar lordosis disappears, this is verified by inserting one hand between the patient’s lumbar spine and the examining table.
With the patient in this position, the examiner immobilizes the pelvis in its normal position. The pelvis should exhibit about 12° of anterior inclination. This is what creates the lumbar lordosis.
An increased flexion contracture in the hip can be compensated for by an increase in lumbar lordosis, in which case the patient only appears to assume a normal position.
What does a positive Thomas Test mean?
The test is positive if the thigh is raised off the surface of the table. A positive test indicates a decrease in flexibility in the rectus femoris or iliopsoas muscles or both.
In normal hip (Negative Thomas test), extension is only possible up to the neutral position (0°); the thigh lies at on the surface of the examining table. Further flexion can tilt the pelvis further upright. So long as the leg being examined remains in contact with the examining table, the angle of pelvic tilt achieved corresponds to the maximum hyperextension of the hip.
The flexion contracture can be quantified by measuring the angle that the flexed, affected leg forms with the examining table.
One of the limitations of this test is that it merely determines the amount of hip extension possible at any given degree of pelvic flexion. Another problem is that there are better methods of measuring the flexibility of the iliopsoas complex. For example, positioning the patient in prone, stabilizing the pelvis, and then extending the thigh. The precise point at which the pelvis begins to rise marks the end of the hip motion and the beginning of pelvic and spine motion.
Thomas Test Sensitivity & Specificity
Neither the original Thomas Test nor the suggested variations have ever been substantiated for reliability, sensitivity, or specificity1 :
Sensitivity: 31 %
Specificity: 57 %
Modified Thomas Test
A modified thomas test is commonly used to help eliminate the effect of the lumbar curve.
For the modified version of Thomas Test, the patient is positioned in sitting at the end of the bed.
From this position, the patient is asked to lie back, while bringing both knees against the chest. Once in this position, the patient is asked to perform a posterior pelvic tilt.
While the contralateral hip is held in maximum hip flexion by the patient’s hands, the tested limb is lowered over the end of the bed toward the floor.
If normal, the thigh should be parallel with the bed, in neutral rotation, and neither abducted nor adducted, with the lower leg being perpendicular to the thigh and in neutral rotation. There should be 100–110 degrees of knee flexion present with the thigh in line with the table.
If the thigh is raised compared to the table, a decrease in the flexibility of the iliopsoas muscle complex should be suspected.
If the rectus femoris is adaptively shortened, the amount of knee extension should increase with the application of overpressure into hip extension.
If the decrease in flexibility lies with the iliopsoas, attempts to correct the hip position should result in an increase in the external rotation of the thigh.
The application of overpressure into knee flexion can also be used. If the increase in knee flexion produces an increase in hip flexion (the thigh rises higher off the bed), the rectus femoris is implicated, whereas if the overpressure produces no change in the degree of hip flexion, the iliopsoas is implicated.
Hip extension is important for the action of various athletic activities. A restriction of hip extension has been thought to lead to an overstriding gait and increased impact forces during running, which may increase the risk of tibial stress fracture.
A restriction of the hip extension may be associated with contracture in the hip flexor muscles. A postural hypothesis related to hamstring strains is that contracted hip flexors lead to an anterior pelvic tilt, which may predispose runner athletes to hamstring strains.
For individuals with low back pain that is sensitive to spinal extension, contracted hip flexors may lead these individuals to perform spinal movements that lead to increased spinal extension, as the individual lacks movement options due to their hip extension limitations.
This test can also be used to assess the flexibility of the Tensor fascia latae (TFL), if the hip of the tested leg is maximally adducted while monitoring the ipsilateral the anterior superior iliac spine (ASIS)for motion. There should be 20 degrees of hip adduction available.
Flexion contracture of the hip may result from psoas spasm secondary to inflammation or pus in the region of its sheath in the pelvis. This is seen, for example, in appendicitis, appendix abscess or other pelvic inflammatory disease. Examination of the abdomen is essential.
Two things must be remembered when interpreting the results of Thomas Test:
The criteria are arbitrary and have been shown to vary between genders and limb dominance and to depend on the types and the levels of activity undertaken by the individual.
The apparent tightness might simply be normal tissue tension, producing a deviation of the leg because of an increased flexibility of the antagonists.
The iliopsoas muscle, formed by the iliacus and psoas major muscles, is the most powerful hip flexor, while also functioning as a weak adductor and external rotator of the hip.
The iliopsoas attaches to the hip joint capsule, thereby giving it some support.
Since the muscle spans both the axial and appendicular components of the skeleton, it also functions as a trunk flexor, and affords an important element to the vertical stability of the lumbar spine, especially when the hip is in full extension and passive tension is greatest in the muscle.
Theoretically, a sufficiently strong and isolated bilateral contraction of any hip flexor muscle will either rotate the femur toward the pelvis, the pelvis (and possibly the trunk) toward the femur, or both actions simultaneously.
Rectus Femoris Muscle:
The rectus femoris muscle, one of the four quadriceps muscles, is a two-joint muscle that arises from two tendons: one, the anterior or straight, from the anterior inferior iliac spine (AIIS); the other, the posterior or reflected, from a groove above the brim of the acetabulum.
The rectus femoris combines movements of flexion at the hip and extension at the knee.
It functions more effectively as a hip flexor when the knee is flexed, as when a person kicks a ball.
The pectineus is an adductor, flexor, and internal rotator of the hip. Like the iliopsoas, the pectineus attaches to and supports the joint capsule of the hip.
The gracilis , the longest of the hip adductors, is also the most superficial and medial of the hip adductor muscles.
gracilis functions to adduct and flex the thigh and flex and internally rotate the leg.
Tensor Fascia Latae Muscle:
The TFL envelops the muscles of the thigh.
The TFL counteracts the backward pull of the gluteus maximus on the iliotibial band (ITB).
The TFL also flexes, abducts, and externally rotates the hip.
The trochanteric bursa is found deep to this muscle, as it passes over the greater trochanter.
The attachment of the TFL via the ITB to the anterolateral tibia provides a flexion moment in knee flexion and an extension moment in knee extension.
The sartorius muscle is the longest muscle in the body.
The sartorius is responsible for flexion, abduction, and external rotation of the hip, and some degree of knee flexion.
Transverse processes of L1-L5 vertebra
The rectus femoris muscle
Anterior inferior iliac spine AIIS, acetabular rim
Progressive fibrosis of the quadriceps muscle is a condition in which extension contracture of the knee develops in early childhood as a result of fibrosis of one or more components of the quadriceps muscle. The condition is more common in girls than in boys.
The exact cause of progressive fibrosis of the quadriceps is not known. Gunn2 first proposed that it was a sequela of multiple injections of antibiotics into the thigh muscles during early infancy.
The pathophysiology of progressive fibrosis is speculative. It has been proposed that the volume of drug injected in very young infants compresses the capillaries and muscle fibers and causes muscle ischemia, which leads to fibrotic changes. Local necrosis may occur as a result of focal disruption of fibers at the site of injection. The irritative nature of the injected drug may also play a role in producing fibrosis.
The clinical hallmark of progressive fibrosis of the quadriceps is painless, progressive limitation of both active and passive knee flexion with an extension contracture. The vastus intermedius is most commonly involved. Fibrosis occurs more distally than proximally, within and between the muscle fibers.
A dimple in the skin may be present because of the rigid, fibrous septa that extend between the skin and the deep fascia; the dimple deepens with forced flexion of the knee.
Range of motion is painless within the available arc.
The involved muscle is atrophic, with subcutaneous hardness and limitation of motion.
Genu recurvatum may develop in severe cases.
The patella is high riding. Habitual dislocation of the patella may occur in chronic cases.
Knee flexion in these patients is accomplished through lateral dislocation of the patella. With the patella held within the groove of the femur, the knee cannot be flexed. In these patients the vastus lateralis is usually involved. This condition differs from congenital lateral dislocation of the patella in that it is an acquired contracture resulting from progressive fibrosis.
Two different surgical releases have been advocated for the treatment of quadriceps fibrosis:
The first is surgical release of the extension contracture by proximal division of the fibrotic muscular bands, which is often combined with transverse division of the iliotibial tract. This approach is preferred in patients younger than 10 years in whom no radiographic changes are present in the distal end of the femur.
The other surgical approach is V-Y quadricepsplasty to lengthen the extensor mechanism as a whole when the fibrosis is extensive. Postoperative extensor lag may be present but resolves with time in most cases. The extensor lag is more prevalent following V-Y plasty than after proximal release of the fibrotic bands.
When the fibrosis is chronic and genu recurvatum is present, skeletal changes may develop in the distal end of the femur where the articular surface points anteriorly. In such cases it may be necessary to perform distal femoral flexion osteotomy to gain knee flexion and maintain joint congruity.
The modified Thomas test is not a valid measure of hip extension unless pelvic tilt is controlled | Andrew D. Vigotsky, Gregory J. Lehman, Chris Beardsley, Bret Contreras, Bryan Chung, Erin H. Feser PeerJ. 2016; 4: e2325. Published online 2016 Aug 11. doi: 10.7717/peerj.2325 PMCID: PMC4991856.
Gunn DR: Contracture of the quadriceps muscle. A discussion on the etiology and relationship to recurrent dislocation of the patella, J Bone Joint Surg Br 46: 492, 1964.
Clapis, Davis & Davis (2007) Clapis PA, Davis SM, Davis RO. Reliability of inclinometer and goniometric measurements of hip extension flexibility using the modified Thomas test. Physiotherapy Theory and Practice. 2007;24:135–141. doi: 10.1080/09593980701378256.
Harvey D: Assessment of the flexibility of elite athletes using the modified Thomas test. Br J Sports Med 32:68–70, 1998.
Clinical Tests for the Musculoskeletal System 3rd Ed. Book
Mark Dutton, Pt . Dutton’s Orthopaedic Examination, Evaluation, And Intervention, 3rd Edition Book.