22. Hip

Intraarticular pathologies

Hip osteoarthritis (OA)

Intraarticular cartilage degeneration

Labral tears

Loose bodies

Femoro-acetabular impingement (FAI)

Synovitis

Extraarticular pathologies

Greater trochanteric (GT) complex enthesopathies, greater trochanteric bursitis, iliotibial tract tendinopathy (lateral/posterior hip pain)

Iliopsoas tendonitis, snapping hip (anterior hip pain)

Femoral neck stress fracture (pain on weight-bearing)

Deep gluteal syndrome (includes piriformis syndrome), sacroiliac joint pain, athletic pubalgia (trochanteric-pelvic impingement, ischiofemoral impingement, and subspine impingement) (lateral/posterior hip pain)

Myofascial pain (anterior and posterior pain)

Referred pain

Lumbosacral spine disorders and sacroiliac joint arthropathy

Knee pathologies

Intraabdominal pathologies

Others

Fibromyalgia, rheumatoid diseases, avascular necrosis of the femoral head (clinically similar to advanced hip OA)

Anatomy

Bones, Cartilage, and Ligamentous Structures

The hip joint consists of the acetabulum (ilium, ischium, and pubis), the femoral head and neck, the labral fibrocartilage that deepens the socket of the acetabulum, and the iliofemoral, ischiofemoral, and pubofemoral ligaments.

Musculature

Table 22.2 summarizes the core hip muscles and their attachments and functions.

Blood supply : Medial and lateral circumflex artery that are branches of the deep femoral artery.
Innervation : The posterior hip capsule is innervated by branches from the superior gluteal and sciatic nerves, while the anterior capsule is innervated by the articular branches of the obturator nerve, accessory obturator, and femoral nerve (Fig. 22.1). These anterior articular branches have been well studied and implied to be clinically relevant in hip pain and hip denervation. Further details are discussed in Chap. 27 (Hip and Knee joint denervation).

Table 22.2

Core hip muscles and their attachments and functions

Muscle	Principal group Subgroups	Origin	Insertion	Primary action/secondary action
Inferior gemelli	Gluteal region (hip-joint stability) Deep	Ischial tuberosity	Greater trochanter	Femur: lateral rotation
Obturator externus	Gluteal region (hip-joint stability) Deep	Obturator membrane (external surface)	Greater trochanter	Femur: lateral rotation
Obturator internus	Gluteal region (hip-joint stability) Deep	Obturator membrane (internal surface)	Greater trochanter	Femur: lateral rotation
Piriformis	Gluteal region (hip-joint stability) Deep	Anterior aspect of the sacrum	Greater trochanter (superior aspect)	Femur, lateral rotation/femur, abduction
Quadratus femoris	Gluteal region (hip-joint stability) Deep	Ischial tuberosity	Intertrochanteric crest (quadrate tubercle)	Femur: lateral rotation
Superior gemelli	Gluteal region (hip-joint stability) Deep	Ischial spine	Greater trochanter	Femur: lateral rotation
Gluteus maximus	Gluteal region (hip-joint stability) Superficial	Ilium, sacrum, and coccyx	Gluteal tuberosity of femur and iliotibial tract	Hip: extension
Gluteus medius	Gluteal region (hip-joint stability) Superficial	Outer surface of ileum, between top two gluteal lines	Greater trochanter (lateral)	Anterior fibers: Femur: abduction and internal rotation
Gluteus medius	Gluteal region (hip-joint stability) Superficial	Outer surface of ileum, between top two gluteal lines	Greater trochanter (lateral)	Posterior fibers: Femur: abduction and external rotation
Gluteus minimus	Gluteal region (hip-joint stability) Superficial	Outer surface of ilium, between bottom two gluteal lines	Greater trochanter (anterior)	Femur: abduction and internal rotation
Iliopsoas	Thigh, anterior	Psoas: lumbar vertebrae, transverse processes Iliacus: iliac crest and inner plate of ilium	Lesser trochanter of femur	Hip flexion

../images/457420_1_En_22_Chapter/457420_1_En_22_Fig1_HTML.jpg — Fig. 22.1

Articular branches to the anterior hip joint. (Reprinted with permission from Dr. Maria Fernanda Rojas)

Hip Intraarticular Injection

Patient Selection

Injection is indicated in patients with pain from intraarticular hip pathologies (as listed in Table 22.1) lasting longer than 3 months, nonresponsive to pharmacologic and physical therapy. Osteoarthritis (OA) of different stages (II–IV) may be considered but clinical success is less likely with advanced conditions especially “bone-on-bone” situation. Imaging is only recommended in case of atypical presentation or rapid progression of OA.

Ultrasound Scanning

The hip joint can be easily accessed through the anterior synovial recess (∗∗∗) in an anterior approach under ultrasound guidance (Fig. 22.2). Lateral approach to the hip joint is commonly performed for fluoroscopy-guided injection and endoscopy procedures but can be implemented with ultrasound guidance as well. Both approaches are described below.

../images/457420_1_En_22_Chapter/457420_1_En_22_Fig2_HTML.png — Fig. 22.2

Anterior recess of hip. (Figure reprinted with permission from Philip Peng Educational Series)

Anterior Approach

Position: Supine
Probe: Curvilinear 2–6 MHz, linear 5–16 MHz in low BMI patients

Scan 1

Operator stands on the affected side of the patient. Place probe perpendicular to the femur at the upper third of the thigh; it shows the femoral shaft in short axis as a dome-shaped hyperechoic structure (Fig. 22.3).

../images/457420_1_En_22_Chapter/457420_1_En_22_Fig3_HTML.png — Fig. 22.3

Short-axis view of femur. (Reprinted with permission from Dr. Agnes Stogicza)

Scan 2

Scan cephalad without changing the angle of the probe, until femoral bone is no longer dome-shaped, but flattens out. The flat bone marks the anterior surface of the greater trochanter (arrows) (Fig. 22.4).