The hip joint is a multiaxial ball-and-socket joint between the head of the femur and the acetabulum of the hip bone (image). The hip carries the weight of the body and thus requires strength and stability during standing and walking. For these reasons, its range of motion is more limited than at the shoulder joint.

The acetabulum is the socket portion of the hip joint. This space is deep and has a large articulation area for the femoral head, thus giving stability and weight bearing ability to the joint. The acetabulum is further deepened by the acetabular labrum, a fibrocartilage lip attached to the outer margin of the acetabulum. The surrounding articular capsule is strong, with several thickened areas forming intrinsic ligaments. These ligaments arise from the hip bone, at the margins of the acetabulum, and attach to the femur at the base of the neck. The ligaments are the iliofemoral ligament, pubofemoral ligament, and ischiofemoral ligament, all of which spiral around the head and neck of the femur. The ligaments are tightened by extension at the hip, thus pulling the head of the femur tightly into the acetabulum when in the upright, standing position. Very little additional extension of the thigh is permitted beyond this vertical position. These ligaments thus stabilize the hip joint and allow you to maintain an upright standing position with only minimal muscle contraction. Inside of the articular capsule, the ligament of the head of the femur (ligamentum teres) spans between the acetabulum and femoral head. This intracapsular ligament is normally slack and does not provide any significant joint support, but it does provide a pathway for an important artery that supplies the head of the femur.

The hip is prone to osteoarthritis, and thus was the first joint for which a replacement prosthesis was developed. A common injury in elderly individuals, particularly those with weakened bones due to osteoporosis, is a “broken hip,” which is actually a fracture of the femoral neck. This may result from a fall, or it may cause the fall. This can happen as one lower limb is taking a step and all of the body weight is placed on the other limb, causing the femoral neck to break and producing a fall. Any accompanying disruption of the blood supply to the femoral neck or head can lead to necrosis of these areas, resulting in bone and cartilage death. Femoral fractures usually require surgical treatment, after which the patient will need mobility assistance for a prolonged period, either from family members or in a long-term care facility. Consequentially, the associated health care costs of “broken hips” are substantial. In addition, hip fractures are associated with increased rates of morbidity (incidences of disease) and mortality (death). Surgery for a hip fracture followed by prolonged bed rest may lead to life-threatening complications, including pneumonia, infection of pressure ulcers (bedsores), and thrombophlebitis (deep vein thrombosis; blood clot formation) that can result in a pulmonary embolism (blood clot within the lung).

A joint (joynt) is where two or more bones are joined together. Joints can be rigid, like the joints between the bones in your skull, or movable, like knees, hips, and shoulders. Many joints have cartilage (KAHRT-lij) on the ends of the bones where they come together. Healthy cartilage helps you move by allowing bones to glide over one another. It also protects bones by preventing them from rubbing against each other.

Keeping your joints healthy will allow you to run, walk, jump, play sports, and do the other things you like to do. Physical activity, a balanced diet, avoiding injuries, and getting plenty of sleep will help you stay healthy and keep your joints healthy too.

Physical activity

Being physically active is one of the most important things you can do to keep your joints healthy. Regular activity helps keep the muscles around your joints strong and working the way they should. Even people who already have arthritis can benefit from regular physical activity, which will help reduce disability and keep the joints working well. Children and teenagers should get 60 minutes or more of physical activity each day. When exercising or playing sports, be sure to wear the proper protective equipment to avoid injuring your joints. Remember that injuries to your knee early in life can lead to osteoarthritis later on, so be sure to wear protective pads and shoes that fit well. It’s also important to warm up and stretch before exercise. If you have any concerns about your health, talk to your doctor or a physical therapist to find out what kinds of activities are right for you.

Eat a healthy diet

Physical activity, along with a balanced diet, will help you manage your weight. Avoiding excess weight puts less stress on your joints, especially in your knees, hips, and feet. This can help reduce the wear and tear that may lead to arthritis later in life.

Speaking of diet, no specific diet will prevent or cure arthritis. However, eating a balanced diet will help manage your weight and provide a variety of nutrients for overall health. A balanced diet:

• Emphasizes fruits, vegetables, whole grains, and fat-free or low-fat dairy products like milk, cheese, and yogurt.
• Includes protein from lean meats, poultry, seafood, beans, eggs, and nuts.
• Is low in solid fats, saturated fats, cholesterol, salt (sodium), added sugars, and refined grains.
• Is as low as possible in trans fats.
• Balances calories taken in through food with calories burned in physical activity to help maintain a healthy weight.

The pelvic girdle (hip girdle) is formed by a single bone, the hip bone or coxal bone (coxal = “hip”), which serves as the attachment point for each lower limb. Each hip bone, in turn, is firmly joined to the axial skeleton via its attachment to the sacrum of the vertebral column. The right and left hip bones also converge anteriorly to attach to each other. The bony pelvis is the entire structure formed by the two hip bones, the sacrum, and, attached inferiorly to the sacrum, the coccyx (Figure 8.12).

Unlike the bones of the pectoral girdle, which are highly mobile to enhance the range of upper limb movements, the bones of the pelvis are strongly united to each other to form a largely immobile, weight-bearing structure. This is important for stability because it enables the weight of the body to be easily transferred laterally from the vertebral column, through the pelvic girdle and hip joints, and into either lower limb whenever the other limb is not bearing weight. Thus, the immobility of the pelvis provides a strong foundation for the upper body as it rests on top of the mobile lower limbs.

Figure 8.12 Pelvis The pelvic girdle is formed by a single hip bone. The hip bone attaches the lower limb to the axial skeleton through its articulation with the sacrum. The right and left hip bones, plus the sacrum and the coccyx, together form the pelvis.

Hip Bone

The hip bone, or coxal bone, forms the pelvic girdle portion of the pelvis. The paired hip bones are the large, curved bones that form the lateral and anterior aspects of the pelvis. Each adult hip bone is formed by three separate bones that fuse together during the late teenage years. These bony components are the ilium, ischium, and pubis (Figure 8.13). These names are retained and used to define the three regions of the adult hip bone.

Figure 8.13 The Hip Bone The adult hip bone consists of three regions. The ilium forms the large, fan-shaped superior portion, the ischium forms the posteroinferior portion, and the pubis forms the anteromedial portion.

The ilium is the fan-like, superior region that forms the largest part of the hip bone. It is firmly united to the sacrum at the largely immobile sacroiliac joint (see Figure 8.12). The ischium forms the posteroinferior region of each hip bone. It supports the body when sitting. The pubis forms the anterior portion of the hip bone. The pubis curves medially, where it joins to the pubis of the opposite hip bone at a specialized joint called the pubic symphysis.

Ilium

When you place your hands on your waist, you can feel the arching, superior margin of the ilium along your waistline (see Figure 8.13). This curved, superior margin of the ilium is the iliac crest. The rounded, anterior termination of the iliac crest is the anterior superior iliac spine. This important bony landmark can be felt at your anterolateral hip. Inferior to the anterior superior iliac spine is a rounded protuberance called the anterior inferior iliac spine. Both of these iliac spines serve as attachment points for muscles of the thigh. Posteriorly, the iliac crest curves downward to terminate as the posterior superior iliac spine. Muscles and ligaments surround but do not cover this bony landmark, thus sometimes producing a depression seen as a “dimple” located on the lower back. More inferiorly is the posterior inferior iliac spine. This is located at the inferior end of a large, roughened area called the auricular surface of the ilium. The auricular surface articulates with the auricular surface of the sacrum to form the sacroiliac joint. Both the posterior superior and posterior inferior iliac spines serve as attachment points for the muscles and very strong ligaments that support the sacroiliac joint.

The shallow depression located on the anteromedial (internal) surface of the upper ilium is called the iliac fossa. The inferior margin of this space is formed by the arcuate line of the ilium, the ridge formed by the pronounced change in curvature between the upper and lower portions of the ilium. The large, inverted U-shaped indentation located on the posterior margin of the lower ilium is called the greater sciatic notch.

Ischium

The ischium forms the posterolateral portion of the hip bone (see Figure 8.13). The large, roughened area of the inferior ischium is the ischial tuberosity. This serves as the attachment for the posterior thigh muscles and also carries the weight of the body when sitting. You can feel the ischial tuberosity if you wiggle your pelvis against the seat of a chair. Projecting superiorly and anteriorly from the ischial tuberosity is a narrow segment of bone called the ischial ramus. The slightly curved posterior margin of the ischium above the ischial tuberosity is the lesser sciatic notch. The bony projection separating the lesser sciatic notch and greater sciatic notch is the ischial spine.

Pubis

The pubis forms the anterior portion of the hip bone (see Figure 8.13). The enlarged medial portion of the pubis is the pubic body. Located superiorly on the pubic body is a small bump called the pubic tubercle. The superior pubic ramus is the segment of bone that passes laterally from the pubic body to join the ilium. The narrow ridge running along the superior margin of the superior pubic ramus is the pectineal line of the pubis.

The pubic body is joined to the pubic body of the opposite hip bone by the pubic symphysis. Extending downward and laterally from the body is the inferior pubic ramus. The pubic arch is the bony structure formed by the pubic symphysis, and the bodies and inferior pubic rami of the adjacent pubic bones. The inferior pubic ramus extends downward to join the ischial ramus. Together, these form the single ischiopubic ramus, which extends from the pubic body to the ischial tuberosity. The inverted V-shape formed as the ischiopubic rami from both sides come together at the pubic symphysis is called the subpubic angle.

Pelvis

The pelvis consists of four bones: the right and left hip bones, the sacrum, and the coccyx (see Figure 8.12). The pelvis has several important functions. Its primary role is to support the weight of the upper body when sitting and to transfer this weight to the lower limbs when standing. It serves as an attachment point for trunk and lower limb muscles, and also protects the internal pelvic organs. When standing in the anatomical position, the pelvis is tilted anteriorly. In this position, the anterior superior iliac spines and the pubic tubercles lie in the same vertical plane, and the anterior (internal) surface of the sacrum faces forward and downward.

The three areas of each hip bone, the ilium, pubis, and ischium, converge centrally to form a deep, cup-shaped cavity called the acetabulum. This is located on the lateral side of the hip bone and is part of the hip joint. The large opening in the anteroinferior hip bone between the ischium and pubis is the obturator foramen. This space is largely filled in by a layer of connective tissue and serves for the attachment of muscles on both its internal and external surfaces.

Several ligaments unite the bones of the pelvis (Figure 8.14). The largely immobile sacroiliac joint is supported by a pair of strong ligaments that are attached between the sacrum and ilium portions of the hip bone. These are the anterior sacroiliac ligament on the anterior side of the joint and the posterior sacroiliac ligament on the posterior side. Also spanning the sacrum and hip bone are two additional ligaments. The sacrospinous ligament runs from the sacrum to the ischial spine, and the sacrotuberous ligament runs from the sacrum to the ischial tuberosity. These ligaments help to support and immobilize the sacrum as it carries the weight of the body.

Figure 8.14 Ligaments of the Pelvis The posterior sacroiliac ligament supports the sacroiliac joint. The sacrospinous ligament spans the sacrum to the ischial spine, and the sacrotuberous ligament spans the sacrum to the ischial tuberosity. The sacrospinous and sacrotuberous ligaments contribute to the formation of the greater and lesser sciatic foramina.

The sacrospinous and sacrotuberous ligaments also help to define two openings on the posterolateral sides of the pelvis through which muscles, nerves, and blood vessels for the lower limb exit. The superior opening is the greater sciatic foramen. This large opening is formed by the greater sciatic notch of the hip bone, the sacrum, and the sacrospinous ligament. The smaller, more inferior lesser sciatic foramen is formed by the lesser sciatic notch of the hip bone, together with the sacrospinous and sacrotuberous ligaments.

The space enclosed by the bony pelvis is divided into two regions (Figure 8.15). The broad, superior region, defined laterally by the large, fan-like portion of the upper hip bone, is called the greater pelvis (greater pelvic cavity; false pelvis). This broad area is occupied by portions of the small and large intestines, and because it is more closely associated with the abdominal cavity, it is sometimes referred to as the false pelvis. More inferiorly, the narrow, rounded space of the lesser pelvis (lesser pelvic cavity; true pelvis) contains the bladder and other pelvic organs, and thus is also known as the true pelvis. The pelvic brim (also known as the pelvic inlet) forms the superior margin of the lesser pelvis, separating it from the greater pelvis. The pelvic brim is defined by a line formed by the upper margin of the pubic symphysis anteriorly, and the pectineal line of the pubis, the arcuate line of the ilium, and the sacral promontory (the anterior margin of the superior sacrum) posteriorly. The inferior limit of the lesser pelvic cavity is called the pelvic outlet. This large opening is defined by the inferior margin of the pubic symphysis anteriorly, and the ischiopubic ramus, the ischial tuberosity, the sacrotuberous ligament, and the inferior tip of the coccyx posteriorly. Because of the anterior tilt of the pelvis, the lesser pelvis is also angled, giving it an anterosuperior (pelvic inlet) to posteroinferior (pelvic outlet) orientation.

Figure 8.15 Male and Female Pelvis The female pelvis is adapted for childbirth and is broader, with a larger subpubic angle, a rounder pelvic brim, and a wider and more shallow lesser pelvic cavity than the male pelvis.

Comparison of the Female and Male Pelvis

The differences between the adult female and male pelvis relate to function and body size. In general, the bones of the male pelvis are thicker and heavier, adapted for support of the male’s heavier physical build and stronger muscles. The greater sciatic notch of the male hip bone is narrower and deeper than the broader notch of females. Because the female pelvis is adapted for childbirth, it is wider than the male pelvis, as evidenced by the distance between the anterior superior iliac spines (see Figure 8.15). The ischial tuberosities of females are also farther apart, which increases the size of the pelvic outlet. Because of this increased pelvic width, the subpubic angle is larger in females (greater than 80 degrees) than it is in males (less than 70 degrees). The female sacrum is wider, shorter, and less curved, and the sacral promontory projects less into the pelvic cavity, thus giving the female pelvic inlet (pelvic brim) a more rounded or oval shape compared to males. The lesser pelvic cavity of females is also wider and more shallow than the narrower, deeper, and tapering lesser pelvis of males. Because of the obvious differences between female and male hip bones, this is the one bone of the body that allows for the most accurate sex determination. Table 8.1 provides an overview of the general differences between the female and male pelvis.

Overview of Differences between the Female and Male Pelvis

Table8.1

Forensic Pathology and Forensic Anthropology

A forensic pathologist (also known as a medical examiner) is a medically trained physician who has been specifically trained in pathology to examine the bodies of the deceased to determine the cause of death. A forensic pathologist applies his or her understanding of disease as well as toxins, blood and DNA analysis, firearms and ballistics, and other factors to assess the cause and manner of death. At times, a forensic pathologist will be called to testify under oath in situations that involve a possible crime. Forensic pathology is a field that has received much media attention on television shows or following a high-profile death.

While forensic pathologists are responsible for determining whether the cause of someone’s death was natural, a suicide, accidental, or a homicide, there are times when uncovering the cause of death is more complex, and other skills are needed. Forensic anthropology brings the tools and knowledge of physical anthropology and human osteology (the study of the skeleton) to the task of investigating a death. A forensic anthropologist assists medical and legal professionals in identifying human remains. The science behind forensic anthropology involves the study of archaeological excavation; the examination of hair; an understanding of plants, insects, and footprints; the ability to determine how much time has elapsed since the person died; the analysis of past medical history and toxicology; the ability to determine whether there are any postmortem injuries or alterations of the skeleton; and the identification of the decedent (deceased person) using skeletal and dental evidence.

Due to the extensive knowledge and understanding of excavation techniques, a forensic anthropologist is an integral and invaluable team member to have on-site when investigating a crime scene, especially when the recovery of human skeletal remains is involved. When remains are bought to a forensic anthropologist for examination, he or she must first determine whether the remains are in fact human. Once the remains have been identified as belonging to a person and not to an animal, the next step is to approximate the individual’s age, sex, race, and height. The forensic anthropologist does not determine the cause of death, but rather provides information to the forensic pathologist, who will use all of the data collected to make a final determination regarding the cause of death.

Muscles of the Thigh

What would happen if the pelvic girdle, which attaches the lower limbs to the torso, were capable of the same range of motion as the pectoral girdle? For one thing, walking would expend more energy if the heads of the femurs were not secured in the acetabula of the pelvis. The body’s center of gravity is in the area of the pelvis. If the center of gravity were not to remain fixed, standing up would be difficult as well. Therefore, what the leg muscles lack in range of motion and versatility, they make up for in size and power, facilitating the body’s stabilization, posture, and movement.

Gluteal Region Muscles That Move the Femur

Most muscles that insert on the femur (the thigh bone) and move it, originate on the pelvic girdle. The psoas major and iliacus make up the iliopsoas group. Some of the largest and most powerful muscles in the body are the gluteal muscles or gluteal group. The gluteus maximus is the largest; deep to the gluteus maximus is the gluteus medius, and deep to the gluteus medius is the gluteus minimus, the smallest of the trio (image and image).

The tensor fascia latae is a thick, squarish muscle in the superior aspect of the lateral thigh. It acts as a synergist of the gluteus medius and iliopsoas in flexing and abducting the thigh. It also helps stabilize the lateral aspect of the knee by pulling on the iliotibial tract (band), making it taut. Deep to the gluteus maximus, the piriformis, obturator internus, obturator externus, superior gemellus, inferior gemellus, and quadratus femoris laterally rotate the femur at the hip.

The adductor longus, adductor brevis, and adductor magnus can both medially and laterally rotate the thigh depending on the placement of the foot. The adductor longus flexes the thigh, whereas the adductor magnus extends it. The pectineus adducts and flexes the femur at the hip as well. The pectineus is located in the femoral triangle, which is formed at the junction between the hip and the leg and also includes the femoral nerve, the femoral artery, the femoral vein, and the deep inguinal lymph nodes.

Thigh Muscles That Move the Femur, Tibia, and Fibula

Deep fascia in the thigh separates it into medial, anterior, and posterior compartments (see image and image). The muscles in the medial compartment of the thigh are responsible for adducting the femur at the hip. Along with the adductor longus, adductor brevis, adductor magnus, and pectineus, the strap-like gracilis adducts the thigh in addition to flexing the leg at the knee.

The muscles of the anterior compartment of the thigh flex the thigh and extend the leg. This compartment contains the quadriceps femoris group, which actually comprises four muscles that extend and stabilize the knee. The rectus femoris is on the anterior aspect of the thigh, the vastus lateralis is on the lateral aspect of the thigh, the vastus medialis is on the medial aspect of the thigh, and the vastus intermedius is between the vastus lateralis and vastus medialis and deep to the rectus femoris. The tendon common to all four is the quadriceps tendon (patellar tendon), which inserts into the patella and continues below it as the patellar ligament. The patellar ligament attaches to the tibial tuberosity. In addition to the quadriceps femoris, the sartorius is a band-like muscle that extends from the anterior superior iliac spine to the medial side of the proximal tibia. This versatile muscle flexes the leg at the knee and flexes, abducts, and laterally rotates the leg at the hip. This muscle allows us to sit cross-legged.

The posterior compartment of the thigh includes muscles that flex the leg and extend the thigh. The three long muscles on the back of the knee are the hamstring group, which flexes the knee. These are the biceps femoris, semitendinosus, and semimembranosus. The tendons of these muscles form the popliteal fossa, the diamond-shaped space at the back of the knee.

Introduction

The hip joint is a ball and socket joint that is the point of articulation between the head of the femur and the acetabulum of the pelvis. The joint is a diarthrodial joint with its inherent stability dictated primarily by its osseous components/articulations.  The primary function of the hip joint is to provide dynamic support to the weight of the body/trunk while facilitating force and load transmission from the axial skeleton to the lower extremities, allowing mobility.

Structure and Function

The hip joint connects the lower extremities with the axial skeleton. The hip joint allows for movement in three major axes, all of which are perpendicular to one another. The location of the center of the entire axis is at the femoral head. The transverse axis permits flexion and extension movement. The longitudinal axis, or vertically along the thigh, allows for internal and external rotation. The sagittal axis, or forward to backward, allows for abduction and adduction.

In addition to movement, the hip joint facilitates weight-bearing. Hip stability arises from several factors. The shape of the acetabulum. Due to the depth of the acetabulum, it can encompass almost the entire head of the femur. There is an additional fibrocartilaginous collar surrounding the acetabulum, the acetabular labrum, which provides the following functions:

• Load transmission

• Negative pressure maintenance (i.e., the "vacuum seal") to enhance hip joint stability

• Regulation of synovial fluid hydrodynamic properties

The hip joint capsule and capsular ligaments

In general, the hip joint capsule is tight in extension and more relaxed in flexion.  The capsular ligaments include the iliofemoral ligament (Y ligament of Bigelow), and the pubofemoral and ischiofemoral ligaments.  The iliofemoral ligament is the strongest ligament in the body and attaches the anterior inferior iliac spine (AIIS) to the intertrochanteric crest of the femur.  The pubofemoral ligament prevents excess abduction and extension, ischiofemoral prevents excess extension, and the iliofemoral prevents hyperextension.

The ligamentum teres (ligament of the head of the femur) are located intracapsular and attach the apex of the cotyloid notch to the fovea of the femoral head. The ligamentum teres serves as a carrier for the foveal artery (a posterior division of the obturator artery), which supplies the femoral head in the infant/pediatric population. This relative vascular contribution to the femoral head blood supply is negligible in adults. Injuries to the ligamentum teres can occur in dislocations, which can cause lesions of the foveal artery, resulting in osteonecrosis of the femoral head. 

Embryology

By gestational age weeks 4 to 6, the hip joint begins to develop from mesoderm. By seven weeks gestational age, a cleft forms in the precartilage cells, which are programmed to form the femoral head and acetabulum. By 11 weeks of gestational age, the hip joint has mostly formed. The acetabular cartilage completely encircles the femoral head.

Blood Supply and Lymphatics

There are numerous variations in the blood supply to the hip. The most common variant results in blood supply coming from the medial circumflex and lateral circumflex femoral arteries, each of which is a branch of the profunda femoris (deep artery of the thigh). The profunda femoris is a branch of the femoral artery which travels posteriorly. There is an additional contribution from the foveal artery (artery to the head of the femur), a branch of the posterior division of the obturator artery, which travels in the ligament of the head of the femur. The foveal artery helps avoid avascular necrosis with disruption of the medial and lateral circumflex arteries. There are two significant anastomoses. The cruciate anastomosis supports the upper thigh and the trochanteric anastomosis, which supports the head of the femur.

Lymphatic drainage from the anterior aspect drains to the deep inguinal nodes, while the medial and posterior aspects drain into the internal iliac nodes. 

Nerves

The hip joint receives innervations from the femoral, obturator, superior gluteal nerves.

Muscles

Muscles of the hip joint can be grouped based upon their functions relative to the movements of the hip.

• Flexion: Primarily accomplished via the psoas major and the iliacus, with some assistance from the pectineus, rectus femoris, and the sartorius. 

• Extension: Primarily accomplished via the gluteus maximus as well as the hamstring muscles.

• Medial rotation: Primarily accomplished by the tensor fascia latae and fibers of the gluteus medius and minimus. 

• Lateral rotation: Primarily accomplished by the obturator muscles, the quadratus femoris, and the gemelli with assistance from the gluteus maximus, sartorius, and piriformis.

• Adduction: Primarily accomplished by the adductor longus, brevis, and magnus with assistance from the gracilis and pectineus 

• Abduction: Primarily accomplished by the gluteus medius and minimus with assistance from the tensor fascia latae and sartorius.

Surgical Considerations

Total hip arthroplasty (THA) is an elective procedure for patients with hip pain secondary to degenerative conditions. THA is a highly effective procedure that relieves pain and restores function to improve quality of life. THA is indicated for patients who have failed other conservative methods, including corticosteroid injections, physical therapy, weight reduction, or previous surgical treatments.

Approaches

Surgeons can utilize any number of strategies for the THA procedure. The three most common approaches are as follows:

Posterolateral

This is the most common approach for primary and revision THA cases. This dissection does not utilize a true internervous plane. The intermuscular interval involves blunt dissection of the gluteus maximus fibers and sharp incision of the fascia lata distally. The deep dissection involves a meticulous dissection of the short external rotators and capsule. Care is necessary to protect these structures as they are later repaired back to the proximal femur via trans-osseous tunnels.

A significant advantage of this approach is the avoidance of hip abductors. Other benefits include the excellent exposure provided for both the acetabulum and the femur and the optional extensile conversion in the proximal or distal direction. Historically, some studies comparing this approach to the direct anterior (DA) approach have cited higher dislocation rates in the former approach. This data remains inconclusive and controversial as the literature has not established a definitive consensus, especially when comparing the posterior approach technique that utilizes an optimal soft tissue repair at the conclusion of the THA procedure.

Direct Anterior (DA)

The DA approach is becoming increasingly popular among THA surgeons. The internervous interval is between the tensor fascia lata (TFL) and sartorius on the superficial end, and the gluteus medius and rectus femoris (RF) on the deep side. DA THA advocates cite the theoretical decreased hip dislocation rates in the postoperative period and the avoidance of the hip abduction musculature.

The disadvantages include the learning curve associated with the approach, as the literature documents the decreased complication rates after a surgeon surpasses the more than 100-case mark. Other disadvantages include increased wound complications, difficult femoral exposure, the risk of lateral femoral cutaneous nerve (LFCN) paresthesias, and a potentially higher rate of intra-operative femur fractures. Finally, many surgeons need access to a specialized operating table with appropriately trained personnel and surgical technicians to assist in the procedure. Although the latter is not always necessary, learning to do the procedure on a regular operating table also requires a substantial learning curve that one must consider.

Anterolateral

Compared to the other approaches, the anterolateral (AL) approach is the least commonly used approach secondary to its violation of the hip abductor mechanism. The interval exploited includes that of the TFL and gluteus medius musculature; this may lead to a postoperative limp as the tradeoff of a theoretically decreased dislocation rate.

Clinical Significance

Congenital Hip Dislocation/Dysplasia

Also known as developmental dysplasia of the hip, this can arise when there are problems with the development of the hip joint in utero. Risk factors include breech presentation, positive family history, and oligohydramnios. Diagnosis is possible via physical exam with the Barlow and Ortolani maneuvers, which assess joint stability. Additional characteristic findings are leg length asymmetry as well as asymmetric inguinal skin folds.

The ultimate goal of treatment is the open or closed reduction of the femoral head back into the acetabulum. The earlier treatment starts, the better the outcomes. Mild cases can correct spontaneously by two weeks. When subluxation persists for more than two weeks, it indicates the need for treatment. Standard treatment is the use of the Pavlik Harness, which positions the hips into flexion and abduction for six weeks full-time, followed by six weeks part-time.

Traumatic Conditions

Commonly seen in the setting of trauma, posterior dislocation occurs in the setting of high-energy trauma or motor vehicle accidents (MVAs). The femoral head is transmitted posteriorly, injuring the hip joint capsule.  The affected lower extremity presents in a shortened, internally rotated position.  In all traumatic injuries, there is extensive soft tissue injury about the hip joint and capsule, and in the vast majority of presentations, there will be an associated posterior wall (acetabular) fracture and/or femoral head fracture.  The positioning of the hip often determines the associated acetabular injury.

Patients will typically present with significant pain and inability to bear weight. Approximately 10% of cases may have concurrent damage to the sciatic nerve. Treatment consists of both nonoperative and operative measures. In the acute setting, emergent closed reduction is recommended within six hours of the injury.  Following a successful closed reduction, a CT scan can assess and evaluate the extent of associated osseous injuries.  Additionally, the presence of incarcerated fragments in the joint is of utmost importance as appreciably large fragments will not only prevent the complete reduction of the native hip joint but these fragments also potentially can cause further intra-articular damage and chondral injuries secondary to mechanical abrasion and pathologic contact/abutment.

Irreducible dislocations, those with evidence of incarcerated fragments, and delayed presentations are treated via operative open reduction urgently. Open reduction with internal fixation is the recommendation for complex dislocations with evidence of acetabular or femoral fractures.

Osteoarthritis of the Hip

Most commonly presents in adults, greater than 40 years old. Symptoms include pain, disability, ambulatory dysfunction, and stiffness/contracture.  The patient typically feels pain in the anterior groin, and occasionally involving the buttocks and lateral thigh. Some patients can develop generalized hip referred pain of the knee. It is crucial to consider and/or rule out co-existing lumbar spinous pathology/radiculopathy, and ipsilateral knee conditions. 

The pathogenesis involves wear and tear on the joint cartilage, which over time, leads to decreased protective joint space. As bones begin to rub on one another, they attempt to make up for the lost cartilage and form bone spurs or osteophytes. Nonsurgical treatments involve lifestyle modifications such as weight loss, or minimizing activates that exacerbate pain. Physical therapies, the use of assistive devices, and medications such as NSAIDs, acetaminophen, and corticosteroids also show evidence of effectiveness. For patients whose pain is still irretraceable, surgical intervention may need to be required. Surgical options include osteotomy, hip resurfacing, and total hip replacement.