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Lower Limb Anatomy: The Hip Joint

Table of Contents

Image: “Pelvis” by Phil Schatz. License: CC BY 4.0

The hip joint

The hip joint is a so-called Nut joint, a special form of the ball joint. The joint partners are those Acetabular fossa (hip socket) of the pelvis and that Caput femoris (femoral head) of the thigh bone. It has both a stabilizing and moving function and is capable of flexion / extension, abduction / adduction and internal / external rotation. Thus, the hip joint has three degrees of freedom, can execute movements over all three axes and levels and is slowed down by osseous, capsuloligamentary and possibly muscular structures.

Osseous structures and articular surfaces of the coxae


The Aztebabulum is made up of the three parts of the Os coxae, namely Os ilium (cranial), Os pubis (ventral) and Os ischii (caudal) together. They meet in the so-called Y-joint, which gets its name from the fact that the bony lines are reminiscent of a Y. The Y-joint is completely closed between the ages of 14 and 16 and forms the proximal articular surface of the hip joint. The articular surface is concave and does not completely enclose the femoral head of the thigh.

Acetabular labrum

This is a structure that is formed from tight connective tissue and fiber cartilage and looks roughly triangular when viewed directly. It forms a kind of ring around the acetabulum and is fixed on the Limbus acetabuli, the osseous ridge that surrounds the acetabulum proximally. The tip of the labrum points directly into the joint and serves to enlarge the joint socket area and can deform during movements in order to ensure a greater range of motion without entrapment.

Acetabular notch

The acetabular notch is a notch in the distal rim of the acetabulum on which there is no labrum. It represents the suture surface between the pubis and ischii and is covered by the transverse acetabular ligament. This ligament connects the two end parts (horns) of the fascies lunata.

Fascies lunata

The Fascies lunata is a crescent-shaped structure covered with cartilage in the acetabulum which ends dorsally and ventrally with an end part or horn. The horns are fixed distally by the transverse acetabular ligament. The posterior horn is more flat than the anterior horn and the cartilage is thicker in the medial area.

Acetabular fossa

The Acetabular fossa is a deepening of the facies lunata in the medial area. That is in this recess Pulvinar acetabulare from loose fatty connective tissue, as well as that Ligementum capitis femoris. The stored fatty tissue creates a vacuum, which should support or guarantee the stability of the joint. In the distal direction, the area is closed by the transverse acetabular ligament.

Osseous structures and articular surfaces of the femur

We differentiate between direct-joint and near-joint femoral parts:

Directly articulated femoral parts
Femoral parts near the joint
  • Collum femoris
  • Trochanter major and minor
  • Linea intertrochanterica
  • Crista intertrochanterica
  • Trochanteric fossa
  • Linea aspera
  • Gluteal tuberosity
  • Linea pectinea

Caput ossis femoris

The spherical, convex Head femoris is the articulating surface of the thigh and forms the distal part of the hip joint.

Fovea capitis femoris

The Fovea capitis femoris is a depression on the femoral head in the fourth or dorso-caudal quadrant and serves as an insertion surface for the Ligamentum capitis femoris. Cranial to the fovea is the thickest layer of cartilage of the femoral head with a thickness of up to 4 millimeters.

Collum femoris

The Collum femoris connects the femoral head with the femoral shaft and goes into the Linea intertrochanterica (ventral) and the Crista intertrochanterica (dorsal) above.

Greater trochanter

The Greater trochanter is a Apophysis and lies lateral to the Trochanteric fossa. It serves as the approach for that Gluteus medius and minimus muscles, Piriformis muscle, Obturator internus muscle and the Musculi gemelli.

Lesser trochanter

The “little brother of the greater trochanter” is medial to the Linea intertrochanterica and is, among other things, the starting area for the Iliopsoas muscle.

Linea intertrochanterica

The Linea intertrochanterica lies in the ventral area between the greater and lesser trochanter and serves as a starting point for the Iliofemoral ligament and as the origin for the Vastus medialis muscle.

Crista intertrochanterica

The Crista intertrochanterica is an osseous ridge that connects the greater and lesser trochanters and serves, among other things, as an insertion point for the capsule of the hip joint.

Trochanteric fossa

The Tochanteric fossa is a depression dorso-medial to the greater trochanter. It serves as the approach of Obturator muscles externus et internus and Musculi gemelli superior et inferior.

Linea aspera

Similar to the Crista is also the Linea aspera an osseous ridge that is dorsal to the femoral shaft. It is the starting point for that Gluteus maximus muscle, the Adductor longus, brevis et magnus muscles and the Pectineus muscle and point of origin for the Vastus medialis and lateralis muscles and Biceps femoris caput breve muscle.

Gluteal tuberosity

The Gluteal tuberosity lies cranial to the Linea aspera and serves the Gluteus maximus muscle as an approach.

Linea pectinea

This lies ventral to the Linea aspera in the direction of the greater trochanter and is the insertion point of the Pectineus muscle.

Functional anatomy: angles in the femoral area

There are two angles in the femoral area that doctors and therapists need to know: CCD angle and Antetorsion angle.

CCD angle

The Centrum-Collum-Diaphysen-Winkel is formed by the angle of inclination of the femoral neck axis to the femoral shaft axis. The femoral neck axis runs through the center of the head while the femoral shaft axis runs approximately in the medullary canal of the shaft. In newborns the angle is around 150 degrees, after the end of growth the norm is around 130 degrees.

Antetorsion angle

The ventrally open Antetorsion angle is formed by the femoral neck axis. Newborns have an anteversion angle of 30-40 degrees, the normal value in adults is 12 degrees.

The joint capsule of the hip joint

The joint capsule of the hip joint is one of the strongest capsules in our musculoskeletal system. It is tight, funnel-shaped and tight-fitting and consists of two layers: Membrana fibrosa and Synovial membrane.

Membrana fibrosa

The Membrana fibrosa is firm and thick-walled with fibril bundles running longitudinally and diagonally. She advertises on Acetabular rim, the Ligemantum transversum acetabuli and the Linea intertrochanterica of the ventral femur. The dorsal starting point is that Collum femoris medial to the crista intertrochanterica. It is occupied with mechanoreceptors that send deeply sensitive afferents to the central nervous system.

Synovial membrane

Insertion of the Synovial membrane is the outer edge of the base of the Acetabular labrum. The fact that the tapering edge of the labrum does not articulate with the membrane creates the between the capsule and the labrum Perilimbic recess. Ventral insertion points are located along the cartilage-bone border, the dorsal attachments are proximal to the intertrochanteric crest.

The membrana forms additional folds in this region, which are called Frenula capsulae are designated. They serve as guide lines for vessels and thus supply the femoral neck with blood on the way to the femoral head. Furthermore, the synovial membrane forms a tube around the femoral capitis ligament and closes the joint against the acetabular notch and the acetabular fossa.

The ligaments and bursae of the hip joint

The ligaments of the hip joint are used to guide and limit movements and to stabilize the hip joint as a whole. In anatomy, a distinction is made between intra-articular and extra-atricular ligaments:

Intra-articular ligaments
  • Ligamentum capitis femoris
  • Transverse acetabular ligament
Extra-articular ligaments
  • Iliofemoral ligament
  • Pubofemoral ligament
  • Ischiofemoral ligament
  • Zona orbicularis

Ligamentum capitis femoris

The Ligamentum capitis femoris lies intra-articularly and is covered by a synovial membrane. The fiber bundles pull from Anterior and posterior horns of the lunata fascies as well as the cranial border of the transverse acetabular ligament to the fossa. It is used to supply blood to the femoral head by providing both the Ramus acetabularis as well as the Obturator artery carries with it. In the movement combination flexion / adduction / external rotation it comes under tension. A special feature of this volume is that it is often referred to as in other medical textbooks and journals Ligamentum teres femoris referred to as.

Transverse acetabular ligament

By bridging the acetabular notch, this ligament supports the femoral head from caudally and connects the Ends of the labrum (outer layer) as well as the two Horns of the fascies lunata (inner layer).

Iliofemoral ligament

This band is structured in a V-shape and is divided into Pars lateralis and Pars medialis. The common approach is that Linea intertrochanterica and the tip of the V is fused with the rectus femoris muscle. The pars lateralis, too Bertini ligament called, counts as the strongest ligament in the human body, as it can withstand tensile loads of up to 350 kilograms. The pars medialis is the lower part and is comparatively very thin. The fibers screw into one another and relax when rotated externally.

Pubofemoral ligament

This ligament pulls from Eminentia iliopectinea and Obturator crest to Linea intertrochanterica where it joins the iliofemoral ligament. Further connections arise with the joint capsule and the Zona orbicularis. Ventrally, the iliofemorale and pubofemorale ligaments form the so-called Welcker-Z.

Ischiofemoral ligament

The Ischiofemoral ligament arises on dorso-caudal socket rim and the cranial margin of the sciatic tuberosity and from there it runs in a helical cranio-lateral direction. It advertises on the Inside of the greater trochanter and the Zona orbicularis. The ligament connects to the lateral part of the iliofemoral ligament.

Zona orbicularis

The Zona orbicularis is a ligament loop that receives fibers from all extra-articular ligaments and is fused with the joint capsule, which it physiologically compresses. So it has a very important stabilizing function for the hip joint.

Bursa iliopectinea

Between the iliofemoral and pubofemoral ligaments is the Bursa iliopectineato protect the very thin joint capsule located there. It is located below the tendon of the powerful iliopsoas muscle.

Innervation of the hip joint

A total of five nerves supply the hip joint and its structures. These are the Femoral nerve, Obturator nerve, Sciatic nerve, Superior gluteus nerve and Quadratus femoris nerve.

Femoral nerve

This nerve gives off a branch to the ventral joint area. This branch runs distal to the lateral circumflex artery.

Obturator nerve

The obturator nerve releases fibers into both the hip and knee joints. The fibers from segments L3-L4 pull towards the caudal hip joint.

Sciatic nerve

The ramus acetabularis coxae of the sciatic nerve branches off just before the infrapiriforme foramen and supplies the dorsal hip joint.

Superior gluteus nerve

This nerve supplies the cranio-lateral part of the hip joint.

Quadratus femoris nerve

Branches of the quadratus femoris nerve innervate the dorso-caudal hip joint.

Examples from the clinic of the hip joint

The hip joint is a complex of highly specialized systems and therefore offers a multitude of possible pathologies. A selection of the clinical pictures that occur most frequently is described here.

Degeneration of the cartilage preservation zones

Pathophysiologically, one should know that the articular cartilage can only be nourished and regenerated by applying the right intermittent pressure. If there is a change in the pressure situation due to incorrect loading, the cartilage degenerates, which can lead to hip osteoarthritis over a longer period of time.


Schematic representation of the radiological signs of hip arthrosis: (1) (marginal) osteophyte (2) subchondral sclerosis (3) rubble cyst (4) narrowing of the joint space

With progressive cartilage wear due to non-physiological pressure conditions, osteoarthritis of the hip joint occurs. Patients suffer from loss of movement and pain in the joint, which, depending on the severity of the inflammation, can even occur at rest. The osteoarthritis of the hip joint is Coxarthrosiscalled and is one of the degenerative diseases. Osteoarthritis is considered incurable and in most cases, after unsuccessful conservative therapy, ends in an operation in which a total endoprosthesis is implanted.

Total endoprosthesis (TEP)

In the TEP surgery the capsular ligament apparatus of the hip joint is (partially) removed and the femoral head and the acetabulum are replaced by a metal implant made of titanium. The hip replacement is one of the implant operations that are most frequently performed in German surgical departments. In the acute phase after an endoprosthetic treatment, patients should not flexion over 90 degrees, adduction over the midline or external rotation, as this can lead to postoperative dislocations.

Pectineal bursitis

If patients report pain on contraction of the iliopsosas muscle, then there is one Pectineal bursitis quite likely. Continuous overuse or infection causes inflammation in the bursa, which can become chronic and destroy the tissue.

Instability and dislocation

A dislocation of the hip joint usually occurs as a result of enormous force, as the hip joint is generally very well stabilized. In the event of extreme external rotation, the femoral head can be pushed ventrally and levered out of the socket. Improper patient behavior can lead to postoperative dislocations after TEP implantation.

Femoral neck fracture and necrosis

If the femoral neck breaks, usually after a fall trauma or pre-existing osteoporosis, the blood supply to the femoral head may be interrupted if the fracture line is intracapusual. If such an injury is not treated as quickly as possible (surgically), the failure to supply the bone can lead to post-traumatic necrosis. Necrosis can also occur due to old age, when the ligamentum capitis femoris as a ligament accompanying the arteria obturatoria is no longer adequately supplied and degenerates.

Hip dysplasia

Hip dysplasia is a congenital or acquired malformation of the acetabulum. If this is not diagnosed or diagnosed too late, this leads to irreversible damage to the articulating bone structures, which can result in pain and walking difficulties. Extreme dysplasias make the hip joint chronically unstable and prone to dislocation. Dysplasia is treated either conservatively or surgically, depending on the severity and secondary diagnoses.

Forms of malalignment from femoral head to hip socket in hip dysplasia. A: Normal. B: dysplasia. C: subluxation. D: dislocation

Image: “Forms of malpositions from femoral head to acetabulum in hip dysplasia” by OrthoPat. License: CC BY-SA 3.0

Possible exam questions about the hip joint

The solutions can be found below the references.

1. What degree is the CCD angle after the growth phase?

  1. Approx. 125 degrees
  2. Approx. 130 degrees
  3. Approx. 135 degrees
  4. Approx. 140 degrees
  5. Approx. 145 degrees

2. Which of the following structures does not count among the extra-articular ligaments of the hip joint?

  1. Iliofemoral ligament
  2. Pubofemoral ligament
  3. Ischiofemoral ligament
  4. Ligamentum capitis femoris
  5. Zona orbicularis

3. Which of the following nerves does not supply the hip joint?

  1. Femoral nerve
  2. Obturator nerve
  3. Sciatic nerve
  4. Superior gluteus nerve
  5. Inferior gluteus nerve


Osteoarthritis via Gesundheit.de

Bommas-Ebert, U., Teubner, P. & Voß, R. (2006). Short textbook anatomy and embryology. Stuttgart: Thieme.

Gorenoi, V., Schönermark, M. P. & Hagen, J. (2009) - Joint endoprosthesis registry for Germany

Hochschild, J. (2012). Understanding structures and functions Vol. 2: lumbar spine, pelvis and hip joint, lower extremity. Stuttgart: Thieme.

Hip joint via die-sportorthopaeden.de

Platzer, W. (1999). Pocket Atlas of Anatomy Vol. 1: Musculoskeletal system. Stuttgart: Thieme.

Putz, R. & Pabst, R. [Eds.] (2004).Sobotta 1 + 2 - Atlas of Human Anatomy, limited anniversary edition. Munich: Urban & Fischer.

Netter, Frank H. (2006). Atlas of Human Anatomy - 3rd Edition. Stuttgart: Thieme.

Correct answers: 1B, 2D, 3E

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