Hip Joint Anatomy PDF

Okay, here's the converted text from the images, formatted in Markdown. ### CHAPTER 26: Hip Joint The hip joint is a ball and socket-type synovial joint between the head of the femur, and the acetabulum of the hip bone (Fig. 26.1). It is the largest ball and socket type of joint in the body. Its m...

Okay, here's the converted text from the images, formatted in Markdown. ### CHAPTER 26: Hip Joint The hip joint is a ball and socket-type synovial joint between the head of the femur, and the acetabulum of the hip bone (Fig. 26.1). It is the largest ball and socket type of joint in the body. Its main functions are: (a) to support the body weight during standing, and (b) to transmit the forces generated by movements of trunk femur during walking. It is multiaxial and permits same movements as a shoulder joint in the upper limb, because the long and narrow neck of femur acts as strut and makes an angle with the shaft (neck-shaft angle). However, its range of movements is restricted due to its role in weight-bearing. **TYPE:** Synovial joint of ball and socket variety. **ARTICULAR SURFACES** The head of the femur articulates with the horseshoe-shaped acetabulum of the hip bone to form the hip joint (Fig. 26.2): 1. The head of the femur forms more than half of a sphere. It is covered by the articular hyaline cartilage except for a small pit – the fovea capitis for the ligamentum teres. 2. The acetabulum (Latin acetabulum vinegar cup) presents three features: a horseshoe-shaped lunate surface, acetabular notch, and acetabular fossa. Out of these, only the lunate surface is articular and covered by an articular cartilage. The depth of the acetabulum is increased by the acetabular labrum. *Fig. 26.1 Hip joint: A, line diagram of the right hip joint; B, radiograph of the right hip joint.* *Fig. 26.2 Articular surfaces of the hip joint: A, head of femur; B, acetabulum of the hip bone. Note arrow passing through the acetabular foramen.* Though the proximal and distal articular surfaces are reciprocally curved they are not co-extensive. **LIGAMENTS** The ligaments of the hip joint are as follows: 1. Capsular ligament (joint capsule). 2. Iliofemoral ligament (strongest). 3. Pubofemoral ligament. 4. Ischiofemoral ligament. 5. Transverse acetabular ligament 6. Acetabular labrum. 7. Ligamentum teres femoris (round ligament of the head of femur). **CAPSULAR LIGAMENT** The capsular ligament is a strong and dense fibrous sac which encloses the joint. Its attachments are as under: 1. On the hip bone, it is attached 5-6 mm beyond the acetabular margin, outer aspect of the acetabular labrum and transverse acetabular ligament. 2. On the femur, it is attached anteriorly to the intertrochanteric line and posteriorly 1 cm in front of (medial to) the intertrochanteric crest (Fig. 26.3). * (a) The capsule is thicker anterosuperiorly where the maximal stress occurs, particularly in the standing position. Posteroinferiorly it is thin and loosely attached. * (b) The capsule is made up of two types of fibres – inner circular fibres and outer longitudinal fibres. * (c) The inner circular fibres form a collar around the femoral neck (zona orbicularis). These fibres are not directly attached to the bones. * (d) The outer longitudinal fibres are reflected along the neck toward the head to form the retinacula. The synovial membrane lines the inner aspect of the fibrous capsule, the intracapsular portion of the femoral neck, glenoid labrum (both surfaces), transverse acetabular ligament, ligamentum teres, and fat in the acetabular fossa. It is thin on the deep surface of the iliofemoral ligament where it is compressed against the head (Fig. 26.4). **ILIOFEMORAL LIGAMENT (LIGAMENT OF BIGELOW)** The iliofemoral ligament is an inverted Y-shaped ligament, which lies anteriorly and intimately blended with the capsule. Its apex is attached to the lower half of the anterior inferior iliac spine, and the area between it and above the acetabular margin. Its base is attached to the intertrochanteric line. This ligament consists of three parts – a lateral thick band of oblique fibers, *Fig. 26.3 Attachment of the capsular ligament of hip joint on the femur.* *Fig. 26.4 Coronal section of the right hip joint showing the fibrous capsule and the lining of synovial membrane.* *Fig. 26.5 Iliofemoral and pubofemoral ligaments.* a medial thick band of vertical fibres, and a large central thin portion (Fig. 26.5). *N.B. Iliofemoral ligament is the strongest ligament of the body and prevents the trunk from falling backward in the standing posture.* **PUBOFEMORAL LIGAMENT** The pubofemoral ligament is a triangular ligament with a base above and apex below. It lies inferomedially and supports the joint on this aspect. Its base is attached to the iliopubic eminence, superior pubic ramus, and obturator crest. Inferiorly it blends with the anteroinferior part of the capsule, and medial band of the iliofemoral ligament (Fig. 26.5). **ISCHIOFEMORAL LIGAMENT** (Fig. 26.6) The ischiofemoral ligament is relatively weak and supports the capsule posteriorly. Above it is attached to the ischium posteroinferior to the acetabulum. From ischium its fibers spinal behind the femoral neck to be attached into the greater trochanter deep to the iliofemoral ligament. *Fig. 26.6 Ischiofemoral and iliofemoral ligaments.* **ROUND LIGAMENT OF THE HEAD OF FEMUR** This ligament is also called ligamentum teres of the head of femur. It is a flat triangular ligament with apex attached to the fovea of the head, and its base to the transverse acetabular ligament (Fig. 26.7). It is ensheathed by a conical reflection of the synovial membrane. It does not increase the stability of the joint. It transmits arteries to the head of the femur derived from the acetabular branches of the obturator and medial circumflex femoral arteries. *N.B. Morphologically, the ligament of the head of femur represents the part of the capsule that has been included within the joint.* **ACETABULAR LABRUM** The acetabular labrum is a fibrocartilaginous rim attached to the acetabular margin. It is triangular in cross section. The labrum not only deepens the acetabulum (socket) but grasps the head of femur lightly to hold it in position. **TRANSVERSE ACETABULAR LIGAMENT** It is a part of the acetabular labrum, which bridges the acetabular notch; however, it is devoid of cartilage cells. the acetabular notch thus becomes converted into the foramen which transmits the acetabular vessels and nerves to the hip joint. *Fig. 26.7 Acetabular (glenoid) labrum, transverse acetabular ligament, and ligament of the head of femur.* **STABILITY OF THE HIP JOINT** The stability of the hip joint is provided by the following factors which help to prevent its dislocation: 1. Depth of the acetabulum and narrowing of its mouth by the acetabular labrum. 2. Three strong ligaments (iliofemoral, pubofemoral, and ischiofemoral) strengthening the capsule of the joint. 3. Strength of the surrounding muscles, e.g., gluteus medius, gluteus minimus, etc. 4. Length and obliquity of the neck of femur. **RELATIONS** (Fig. 26.8) The relations of the hip joint are as follows: **Anteriorly:** 1. Tendon of iliopsoas separated from joint by a synovial bursa, pectineus (lateral part), straight head of rectus femoris. 2. Femoral nerve in the groove between the iliacus and the psoas. 3. Femoral artery in front of the psoas tendon. 4. Femoral vein in front of the pectineus. **Posteriorly:** 1. Piriformis, obturator externus, obturator internus, superior and inferior gemelli, quadratus femoris, and gluteus maximus. 2. Superior gluteal nerve and vessels above the piriformis. 3. Inferior gluteal nerve and vessels below the piriformis. 4. Sciatic nerve, posterior cutaneous nerve of the thigh, and nerve to quadratus femoris. **Superiorly:** 1. Reflected head of rectus femoris medially. 2. Gluteus minimus, gluteus medius, and gluteus maximus laterally. **Inferiorly:** 1. Pectineus 2. Obturator externus. *Fig. 26.8 Relations of the hip joint.* *Fig. 26.9 Bursae around the hip joint: A, bursae on greater trochanter; B, subpsoas bursa communicating with the cavity of hip joint (arrow).* **BURSAE AROUND THE HIP JOINT** (Fig. 26.9) These are seven in number: four under gutens maximus, one under gluteus medius, one under gluteus minimus, and one under psoas tendon as under: 1. Between gluteus maximus and smooth area of the ilium lying between the posterior curved line and the outer lip of the iliac crest. 2. Between gluteus maximus and lower part of the outer aspect of the greater trochanter (trochanteric bursa). 3. Between gluteus maximus and ischial tuberosity (ischial bursa). 4. Between the tendon of gluteus maximus and vastus lateralis (gluteofemoral bursa). 5. One bursa under the cover of gluteus medius between it and upper part of the lateral aspect of the greater trochanter. 6. One bursa under the gluteus minimus between it and the anterior aspect of the greater trochanter. 7. One between the iliopubic eminence and the psoas tendon. It is called subpsoas bursa. In 10% of individuals the psoas bursa communicates with the synovial cavity of the hip joint through a gap in the thin part of the capsule between the iliofemoral and pubofemoral ligaments. **Clinical Correlation** *Weaver's bottom:* The subgluteal bursa between the gluteus maximus and ischial tuberosity is frequently inflamed and enlarged in people whose profession requires long periods of sitting, e.g., weavers, leading to a clinical condition called weaver's bottom. **ARTERIAL SUPPLY** The hip joint is supplied by the branches of the following arteries: 1. Medial circumflex femoral artery. 2. Lateral circumflex femoral artery. 3. Obturator artery. 4. Superior gluteal artery. 5. Inferior gluteal artery. *N.B. The arterial supply of the head and neck of the femur is clinically very important. It is derived from the following three sources (Fig. 26.10):* * (a) Acetabular branches of the obturator artery and the medial circumflex femoral arteries These arteries reach the head through the round ligament of the head. * (b) Retinacular vessels (chief source) arise from the medial circumflex femoral artery, run along the neck of the femur through the retinaculum of the capsule. * (c) Nutrient artery of the femur gives few branches to the neck and head of femur. *Fig. 26.10 Arterial supply of the head of femur.* **NERVE SUPPLY** The hip joint is supplied by the following nerves: 1. Femoral nerve via nerve to rectus femoris. 2. A branch from anterior division of the obturator nerve. 3. A branch from the accessory obturator nerve (if present). 4. A branch from nerve to quadratus femoris. L5 5. A branch from the superior gluteal nerve. 6. Atwig from sciatic nerve (occasional). *N.B. Four consecutive spinal segments (L2, L3, L4, L5) control the movements of the hip joints as under:* * *L2 and L3* regulate flexion, adduction, and medial rotation. * *L4 and L5* regulate extension, abduction, and lateral rotation. **MOVEMENTS** The hip joint is a multiaxial joint and permits the following movements: * Flexion and extension. * Abduction and adduction. * Medial and lateral rotation. * Circumduction (combination of the above movements). The flexion and extension movements occur around the transverse axis, medial and lateral rotation occur around the vertical axis, and abductor and adduction movements occur around the anteroposterior axis. **Range of Movements** The flexion is 110°-120°. It is limited by contact of the thigh with the abdomen and adduction is limited by contact with the opposite thigh. The range of other movements is as under: * Extension = 15° * Abduction = 50° **Table 26.1 Muscles producing the movements of the hip joint** | Movements | Muscles producing movements | | :--------------- | :------------------------------------------------------------------------------------------------------------------------------- | | Flexion | Psoas major and iliacus (chief flexor), Sartorius, rectus femoris, and pectineus | | Extension | Gluteus maximus (chief extensor), Hamstring muscles | | Abduction | Gluteus medius and minimus (chief abductors), Tensor fasciae latae and sartorius | | Adduction | Adductor longus, adductor brevis, and adductor magnus (chief adductors), Pectineus and gracilis | | Medial rotation | Anterior fibers of gluteus minimus and medius (chief medial rotators), Tensor fasciae latae | | Lateral rotation | Piriformis, obturator externus, obturator internus and associated gemelli, quadratus femoris (These muscles are generally termed short rotators) | *Fig 26.11 Types of fracture of the neck of femur.* * Medial rotation = 25° * Lateral rotation = 60° The muscles producing the various movements of the hip joint are given in Table 26.1. (i) The joint capsule is loose at birth. (ii) Hypoplasia of the acetabulum and femoral head: In this condition, the head of femur slips upward into the gluteal region because the upper margin of the acetabulum is developmentally deficient. Clinically, it presents as: * Inability of the newborn to abduct the thigh. * Affected limb is shorter in length and externally rotated. * Asymmetry of skin folds of the thighs. * Lurching gait with positive Trendelenburg's sign. (b) Acquired dislocation: The acquired dislocation of the hip joint is uncommon because this joint is very strong and stable. However, it may occur during an automobile accident when the hip joint is flexed, adducted, and medially rotated from the usual position of the lower limb when one is riding in a car. In this position, the joint is unstable because the femoral head is covered posteriorly by a joint capsule and not by the bone During head-on collision, the knee strikes the dashboard and dislocates the hip joint. The head of the femur is forced out of the acetabulum by tearing the capsule posteroinferiorly and lies on the lateral surface of the ilium. This causes shortening and medial rotation of the affected limb. The dislocation of the hip may be posterior (most common), anterior (less common), or central (least common). The sciatic nerve is injured in posterior dislocation. Perthes' disease (pseudocoxalgia): It is a clinical condition characterized by destruction and flattening of the head of femur with an increased joint space in the radiograph. Coxa vara and coxa valga: The normal neck-shaft angle is about 120° in adults and 160° in children. If the neck shaft angle of the femur is reduced (e.g., fracture neck of femur, Perthes disease), it is called coxa vara. If the angle is increased (e.g., congenital dislocation of the hip joint), it is called coxa valga. This may result from Perthes' disease, softening the neck due to rickets. Osteoarthritis: It is a disease of old age. It is characterized by the growth of osteophytes at the articular ends which not only limits the movements but makes them grating and painful. Referred pain of the hip joint: In diseases of the hip joint, such as tuberculosis, the pain is referred to the knee joint because of the common nerve supply of these two joints.