Iliopsoas

Introduction[edit | edit source]

A compound muscle composed of the iliac and psoas muscles

The iliopsoas muscle complex is made up of three muscles that includes the iliacus, psoas major and psoas minor. This complex muscle system can function as a unit or as separate muscles.[1]. Psoas minor is only present in 60% to 65% of individuals[1][2].

The iliopsoas muscle is the primary hip flexor and assists in external rotation of the hip joint, playing an important role in maintaining the strength and integrity of the hip joint. Unilateral psoas contraction assists with lateral motion, while bilateral contraction elevates the trunk from supine.[3]

It is essential for correct standing or sitting lumbar posture and plays a critical role during walking and running[1].

The fascia covering the iliopsoas muscle creates multiple fascial connections, relating the muscle with different viscera and muscle areas[1][4].

Anatomy[edit | edit source]

The iliopsoas musculotendinous unit is part of the inner muscles of the hip. It lies posteriorly at the retroperitoneum level and forms part of the posterior abdominal wall [1]. There are many anatomical variations of the iliopsoas muscle, with the most common origin and insertion listed below[1][2].

Origin:

Psoas major: The transverse processes and lateral surfaces of the vertebral bodies of L1 - L4[1] or T12 - L5[2] and the path involves the intervertebral discs[1][2].

Psaos minor: It originates from T12 and L1 and lies anteriorly to the psoas major[1][2].

Iliacus: It originates on the upper two-thirds of the iliac fossa and the lateral parts of the wing of the sacrum.

Insertion:

Psoas major and iliacus: The psoas major and iliacus join together, pass under the inguinal ligament and insert onto the femoral lesser trochanter[1][2].

Psaos minor: It inserts onto the iliopectineal eminence after converging with the iliac fascia and the psoas major tendon[1][2].

Bursa: The iliopsoas or iliopectineal bursa lies between the bony surfaces of the pelvis and proximal femur and the musculotendinous unit. It is the largest bursa in humans. It has an average length of 5 to 6 cm and width of 3 cm and extends from the iliopectineal eminence to the lower portion of the femoral head[2].

Innervation:

Psaos major and minor: short collateral branches of L1 to L3[1]

Iliacus: femoral nerve or terminal nerve of L1 to L4[1]

Vascular supply: Common iliac artery and external iliac artery[1]

Clinical Relevance[edit | edit source]

Snapping hip syndrome

Snapping hip or coxa saltans is a palpable or auditory snapping with hip joint movement[5]. Internal snapping hip (extra-articular) occurs when the ilipsoas most commonly snaps over the over the iliopectinal eminence or the femoral head[5].

Iliopsoas tendinopathy

"Tendinopathy describes a spectrum of changes that occur in damaged and diseased tendons, leading to pain and reduced function." Millar et al (2021)[6]. The iliopsoas tendon can develop a tendinopathy but is a bit of a "grey area" as there is not much literature about it[7]

Impingement of the Iliopsoas Tendon

Following a total arthroplasty, impingement of the iliopsoas tendon can be a cause of chronic groin pain and limited hip range of movement[8]. The most common cause is due to mechanical irritation of the tendon with the antero-inferior acetabular edge[8].

Iliopsoas Bursitis

Iliopsoas bursitis involves the expansion of the bursa due to synovial fluid and / or hypertrophic synovium[9]. It is often associated with internal coxa saltans or hip joint disease but can also be isolated[9].

In paediatrics, in the presence of spasticity e.g. cerebral palsy and the presence of important contractures, surgery is performed with distal tenotomy. This reduces the difficulty of walking and enables a posture that makes the child independent when possible.

The iliopsoas muscle can cause compression of the femoral nerve and cause knee pain. Before deciding on surgical treatment and releasing of the femoral nerve, the patient should learn stretching exercises to reduce the tension generated by the muscle. Generally, if the patient can follow the physiotherapy indications, the use of surgery can be avoided.

Hypertrophy of the muscle may be responsible for the compression of the femoral nerve and cause knee pain. Before deciding on surgical treatment to release the femoral nerve, the patient should learn stretching exercises to reduce the tension generated by the muscle. Generally, if the patient can follow the physiotherapy indications, the use of surgery can be avoided. [1]

References[edit | edit source]

  1. 1.00 1.01 1.02 1.03 1.04 1.05 1.06 1.07 1.08 1.09 1.10 1.11 1.12 1.13 1.14 Bordoni B, Varacallo M. Anatomy, bony pelvis and lower limb, Iliopsoas Muscle. StatPearls [Internet]. 2021 Jul 21. Available:https://www.ncbi.nlm.nih.gov/books/NBK531508/ (accessed 15.2.2022)
  2. 2.0 2.1 2.2 2.3 2.4 2.5 2.6 2.7 Anderson CN. Iliopsoas: pathology, diagnosis, and treatment. Clinics in sports medicine. 2016 Jul 1;35(3):419-33.
  3. Siccardi MA, Tariq MA, Valle C. Anatomy, bony pelvis and lower limb, psoas major. [1]
  4. Physiopedia Iliopsoas Tendinopathy Available:https://www.physio-pedia.com/Iliopsoas_Tendinopathy?utm_source=physiopedia&utm_medium=related_articles&utm_campaign=ongoing_internal (accessed 15.2.2022)
  5. 5.0 5.1 Yen YM, Lewis CL, Kim YJ. Understanding and treating the snapping hip. Sports medicine and arthroscopy review. 2015 Dec;23(4):194.
  6. Millar NL, Silbernagel KG, Thorborg K, Kirwan PD, Galatz LM, Abrams GD, Murrell GA, McInnes IB, Rodeo SA. Tendinopathy. Nature reviews Disease primers. 2021 Jan 7;7(1):1.
  7. Foglia A, Veuhoff A, Bartolucci C, Secchiari G, Bisciotti GN. Iliopsoas Tendinopathy. The Lower Limb Tendinopathies: Etiology, Biology and Treatment. 2016:85-97.
  8. 8.0 8.1 Di BP, Giuseppe N, Stefano M, Alessandro B, Renato G, Vanni C, Araldo C. Arthroscopic treatment of iliopsoas impingement syndrome after hip arthroplasty. Acta Bio Medica: Atenei Parmensis. 2019;90(Suppl 1):104.
  9. 9.0 9.1 Corvino A, Venetucci P, Caruso M, Tarulli FR, Carpiniello M, Pane F, Sabatino V, Franzese R, Catalano O, Corvino F, Catelli A. Iliopsoas bursitis: The role of diagnostic imaging in detection, differential diagnosis and treatment. Radiology Case Reports. 2020 Nov 1;15(11):2149-52.