Hip Joint

Hip Joint

Gregory R. Waryasz, MD

Assistant

Introduction

The hip joint is a constrained ball-and-socket joint that is relatively fixed to the body by the pelvic girdle.

Much of the stability is derived from the bony architecture. Unlike the shoulder, soft tissue laxity leading to symptoms is uncommon. In the hip extremes of motion can lead to impingement at the soft tissue. When there is overcoverage of the cup or acetabulum this is refered to as pincer impingement and when there is a prominence of the femoral neck cam impingement

The primary function of the hip is to support the weight of the body in both static (standing) and dynamic (walking or running) postures.

Common diseases include osteoarthritis, impingement, tendonitis,

The hallmark of diagnosis is a thourough history. Commonly used diagnostic procedures include plain radiography, CT, MRI, ultrasound, bone scan, and aspiration/injection.

Newborn Pelvis

72111b01.800 bone pelvis innominate bone iliac bone ischium pubic bone femur newborn growth sacrum lumbar vertebra normal Davidoff MD

Newborn Pelvis – Adult Pelvis

72111b01.800 bone pelvis innominate bone iliac bone ischium pubic bone femur newborn growth sacrum lumbar vertebra normal Davidoff MD

24923b01 pelvis bone normal iliac crest ischium pubic symphisis pubic bone hip femur femoral head femoral neck ischium ischial tuberosity greater trochanter lesser trochanter normal anatomy CTscan scout plain film Davidoff MD

Septic Hip Joint

75803c01 young man with hip pain kmee pain and fever bone hip joint acetabulum femur femoral head fluid collection aspirated dx septic arthritis CTscan Courtesy Ashley Davidoff MD 75798 75802 75803 75803c01

The hip joint of the musculoskeletal system is characterized by connecting the lower leg to the pelvic girdle.

It is part of the lower extremity and consists of bone, skeletal muscle, cartilage, synovial tissue, and tendon.

Its unique structural is that it is a multi-axial ball and socket joint with synovial tissue.  The joint is covered by a capsule.

The acetabular labrum is a ring of fibrocartilage that surrounds the acetabulum.

The bones are the femur, ilium, pubis, and ischium.  The ilium, pubis, and ischium make up the acetabulum or socket part of the joint. The femoral head is the ball portion of the joint.

The ligaments are the transverse acetabular ligament, iliofemoral ligament, pubofemoral ligament, ischiofemoral ligament, and the ligament of the head of the femur.

The trochanteric bursa overlies the greater tochanter. The iliofemoral bursa lies across the iliofemoral and pubofemoral ligaments.

The blood supply is from the medial and lateral circumflex arteries distally (retinacular arteries) and the artery to the head of the femur off the obturator artery proximally and venous drainage is from the accompanying veins.

The innervation is from the nerves supplying the muscles going across and that act at the joint according to Hilton’s Law.

The hip joint’s components as well as all other bones, muscles, and ligaments of the body are derived of mesodermal origin in embryo.

The function of the hip joint is to move the leg in all planes of motion; extension, flexion, abduction, adduction, medial rotation, lateral rotation, circumduction.  Movements of the trunk also occur through the hip joint when the legs stay stationary as in sit-ups.

The hip flexors are the iliopsoas, sartorius, tensor fascia lata, rectus femoris, pectineus, adductor longus, adductor brevis, adductor magnus anterior part, and the gracilis.

The hip adductors are the adductor longus, adductor brevis, adductor magnus, gracilis, pectineus, and the obturator externus.

The lateral rotators are the obturator externus, obturator internus, gemelli, piriformis, quadratus femoris, and the gluteus maximus.

The hip extensors are the semitendiosus, semimembranosus, biceps femoris long head, adductor magnus posterior part, and the gluteus maximus.

The hip abductors are the gluteus medius, gluteus minimus, and the tensor of the fascia lata.

The medial rotators are the tensor fascia lata and the anterior parts of the gluteus minimus and gluteus minimus.

Common diseases of the hip joint include arthritis, bursitis, fractures, stress fractures, labrum tears, dislocation/subluxation, Legg-Calve-Perthes disease, Slipped Capital Femoral Epiphysis, septic arthritis, osteomyelitis, congenital hip dysplasia or developmental dysplasia of the hip (DDH), and osteoporosis.

Bursitis can occur at either the iliofemoral or the trochanteric bursa due to overuse/friction leading to inflammation of the bursa.

Fractures can occur with either the acetabulum or the femur. Colloquially the term hip fracture refers to proximal femur fracture.

The acetabular labrum can become torn.

Slipped capital femoral epiphysis (SCFE) is a condition of mostly obese adolescent boys where the fragments on each side of the growth plate on the proximal femur is displaced.  SCFE causes hip, groin, or knee pain with a limp.

Developmental dysplasia of the hip (DDH) is a condition of an unstable joint due to improper formation of the joint. It is usually diagnosed and treated early in infancy.

Legg-Calve-Perthes disease is a form of osteonecrosis/avascular necrosis of the femoral head. Children between the ages of 3-12 have a limp and pain.

Transient synovitis or toxic synovitis is joint pian after a recent viral illness or trauma. It is a self-limiting condition of patients ages 3 to 8 years.

Lyme Arthritis is a condition common in the northeast USA where there is a rheumatologic reaction to Borrelia burgdoferi. It occurs after the patient is bitten by a tick.

Osteomyelitis is an infection of the bone typically caused by a bacteria.

Septic arthritis is an infection of the synovial tissue of the joint with pus in the joitn cavity. The infection is capable of rapidly destroying the joint.

Commonly used diagnostic procedures include clinical history, physical exam, x-ray, CT, and MRI.  Bone density tests or DEXA scans typically look at the proximal femur.  Ultrasound can be used to help with diagnosis of effusion, synovial thickening, and developmental dysplasia of the hip.

It is usually treated with rest, NSAIDs, physical therapy, and surgery. Septic arthritis is treated with surgical washout and antibiotics. Arthritis and fractures can be treated with hemiarthroplasty or total hip replacement. Osteoporosis is treated with bisphosphonates, calcitonin, calcium, and vitamin D.  Legg-Calve Perthes may be treated with abduction bracing initially, then may require surgery later on.  Slipped capital femoral epiphysis is treated surgically. Transient synovitis is treated with NSAIDs.   Developmental dysplasia of the hip is treated initially non-operatively with double diapers or casting.  Surgery may be required for some DDH patients. Labral tears can be treated with physical therapy or arthroscopy.

References

Davis MF, Davis PF, Ross DS. Expert Guide to Sports Medicine. ACP Series, 2005.

Elstrom J, Virkus W, Pankovich (eds), Handbook of Fractures (3rd edition), McGraw Hill, New York, NY, 2006.

Koval K, Zuckerman J (eds), Handbook of Fractures (3rd edition), Lippincott Williams & Wilkins, Philadelphia, PA, 2006.

Lieberman J (ed), AAOS Comprehensive Orthopaedic Review, American Academy of Orthopaedic Surgeons, 2008.

Moore K, Dalley A (eds), Clinically Oriented Anatomy (5th edition), Lippincott Williams & Wilkins, Philadelphia, PA, 2006.

Wheeless’ Textbook of Orthopaedics: Hip Joint Menu (http://www.wheelessonline.com/ortho/hip_joint_index)