Thomas Test

 Thomas Test

What is Thomas Test?

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 hip flexor muscles are (See Below):

  1. The iliopsoas muscle group (It’s made up of 3 muscles, the Psoas Major, Psoas Minor and Iliacus muscle).
  2. The rectus femoris muscle.
  3. Pectineus muscle.
  4. Gracillis muscle.
  5. Tensor fascia latae muscle.
  6. Sartorius muscle.
See Also: Pelvic Anatomy
Thomas Test

How Thomas Test is Performed?

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.

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?

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 :

Modified Thomas Test

A modified thomas test is commonly used to help eliminate the effect of the lumbar curve.

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.

Modified Thomas Test
Modified Thomas Test


Two things must be remembered when interpreting the results of Thomas Test:

  1. 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.
  2. The apparent tightness might simply be normal tissue tension, producing a deviation of the leg because of an increased flexibility of the antagonists.

Related Anatomy

Iliopsoas Muscle:

Rectus Femoris Muscle:

Pectineus Muscle:

Gracilis Muscle:

Tensor Fascia Latae Muscle:

Sartorius Muscle:

Iliopsoas muscleTransverse processes of L1-L5 vertebraLesser trochanterFemoral Nerve
The rectus femoris muscleAnterior inferior iliac spine AIIS, acetabular rimPatella and tibial tubercleFemoral Nerve
Pectineus musclePectineal line of pubisPectineal line of femur Femoral and obturator Nerve
Gracillis muscleInferior symphysis/ pubic arch Proximal medial tibiaObturator Anterior Nerve
Tensor fasciae latae muscle (tensor fasciae femoris)Anterior iliac crestIliotibial bandSuperior gluteal Nerve
Sartorius muscleAnterior superior iliac spine ASISProximal medial tibiaFemoral Nerve
The hip flexor muscles

Progressive Fibrosis of the Quadriceps:

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.

Clinical Symptoms:

  1. 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.
  2. 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.
  3. Range of motion is painless within the available arc.
  4. The involved muscle is atrophic, with subcutaneous hardness and limitation of motion.
  5. Genu recurvatum may develop in severe cases.
  6. The patella is high riding. Habitual dislocation of the patella may occur in chronic cases.
  7. 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:

  1. 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.
  2. 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.


  1. 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.
  2. 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.
  3. 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.
  4. Harvey D: Assessment of the flexibility of elite athletes using the modified Thomas test. Br J Sports Med 32:68–70, 1998.
  5. Clinical Tests for the Musculoskeletal System 3rd Ed. Book
  6. Mark Dutton, Pt . Dutton’s Orthopaedic Examination, Evaluation, And Intervention, 3rd Edition Book.
  7. Millers Review of Orthopaedics, 7th Edition Book.

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