TIS                         
Chapter 7
The Hip


Lower Extremity Problems Involving the Hip and Pelvis

Overview of the Hip Joint: the hip joint, or the acetabulo-femoral joint, is the most structurally stable, yet mobile, single joint in the body. In addition to transmitting large forces between the trunk and the ground, the hip region is a major component of the locomotor system; in participates in elevating and lowering the body, as in sitting or standing, and is important in bringing the foot toward the body or hands, as in putting on a shoe. (Lehmkuhl and smith, p. 259)

Functional Anatomy and Pertinent Biomechanics

The Pelvis: the pelvis provides support and protection to the abdominal organs and transmits forces from the head, arms, and trunk to the lower extremities. (Lehmkuhl and Smith, p. 259) The acetabulum transmits these forces to the lower extremity.

Acetabulum: the cup-like concave socket of the hip joint located on the lateral aspect of the pelvis, which articulates with the head of the femur. The walls of the acetabulum are formed by the three bones of the innominate: anteriorly by the pubis, posterierly by the body of the ischium, and superiorly by the ilium. The acetabulum faces laterally, anteriorly, and inferiorly (Hertling & Kessler, 1996, p.285).

The half-moon shaped acetabulum is deepened by the acetabular labrum, wedge-shaped fibrocartilage, which along with the transverse acetabular ligament, holds the femoral head more firmly in the socket.

The Femur: the longest bone in the body, it consists of a number of important aspects, including the head, the neck, the greater and lesser trochanters, the shaft, and the two condyles. The alignment and the angulation of the neck of the femur in the frontal plane and transverse plane have important biomechanical implications:

Angle of inclination (frontal plane): the angle between the anatomic axis of the femur (the shaft) and the axis of the femoral neck, determined by radiographic examination. In the newborn, this angle is approximately 150 degrees, decreasing with weightbearing as the child matures. The average angle of inclination for adults is 125 degrees (Lehmkuhl & Smith, 1996, p. 285).

Angle of torsion: the angle between the axis of the femoral neck and a line drawn between the femoral condyles; or the degree of torsion/rotation of the femoral neck in relation to the shaft of the femur. Antetorsion: an angle of torsion greater than the upper range of "normal." Retrotorsion: an angle less than the lower range of "normal."

Hip Stability: the hip joint is inherently stable, because of its anatomy. The acetabular socket, deepened by its labrum, serves to tightly enclose the femoral head; the negative pressure within the thick joint capsule causes a vacuum effect, which resists distraction forces; and the ligaments and muscles that cross the joint all serve to tightly hold the femoral head within the acetabulum. The close-packed position of the hip is maximum extension, internal rotation, and abduction.

The joint capsule of the hip is strong and dense, and attaches to the entire periphery of the acetabulum, covering the femoral neck, making the neck intracapsular, as opposed to the trochanters, which are extracapsular. The capsule contributes to joint stability, permitting minimal to no distraction

Three extracapsular ligaments reinforce the joint capsule: Intracapsular Ligaments: Muscles:

Muscles completely surround the hip, providing three planes of movement. The actions of the muscles vary depending on joint position. Therapists' knowledge of muscle testing positions and biomechanics will allow them to be able to isolate specific pathologies with a hip muscle.

Bursae:

The hip has four significant bursae, the trochanteric bursa (located lateral and inferior to the greater trochanter), the iliopectineal and iliopsoas bursae (located anteriorly and medially to the to the neck and acetabulum), and the ischiogluteal (located posteriorly and inferior to the obturator ring).

Disorders of the Hip and Pelvis

Osteoarthritis / Osteoarthrosis / Degenerative Joint Disease: a disease process of joint degeneration in response to overuse, trauma, infection, etc, common to weight bearing joints, such as the hip. Severe degeneration may require surgical intervention, most commonly arthroplasty. Clinical findings: onset of symptoms is usually gradual, and the person is unable to relate it to a specific mechanism of injury. The patient typically feels the pain in the groin, and as it progresses, into the anterior thigh and knee. The person may experience morning stiffness, which decreases as they begin to move around. Many patients experience aching pain after moderate activity, such as walking. Management: treat symptomatically; address capsular tightness via joint mobilization and/or stretching; assess the person's performance of functional activity and alter or augment as needed, strengthen the muscles around the joint, consider non weightbearing activities such as bicycling, swimming, or water aerobics.

Avascular Necrosis of the Femoral Head: a frequent complication following trauma, most commonly femoral neck fractures or dislocations. May be insidious in nature, or due to an injury involving the medial circumflex femoral artery, which supplies most of the blood to the head and neck of the femur, resulting in necrosis. Clinical findings include unexplained aching in the hip, soreness with prolonged sitting, and a general "weak" feeling in the hip. The person may present with an antalgic gait. Radiographs may not detect it until in the advanced stages of necrosis, when flattening of the femoral head is noted. Management: if only part of the head is involved, the person is treated nonoperatively, strengthening and range of motion exercises, gait training with initially limited weightbearing. If the entire head is involved, an arthroplasty is usually indicated.

Slipped Capital Femoral Epiphysis (SCFE): a disorder affecting a skeletally immature femur in which the epiphyseal plate of the head is displaced prior to fusion due to abnormal weakening of the bone. The etiology is unknown, or pituitary however it appears to be associated with endocrine dysfunction. SCFE is usually seen in obese boys typically between the ages of 10 - 15 years. May be due to direct trauma or sudden onset without trauma. 20-30% of SCFE involve both hips. Clinical findings usually include a history of trauma or abnormal/excessive exertion, however absence of trauma is fairly common as well. Pain is sudden in its onset, and is located in the groin, the anterior medial thigh, and often radiating to the medial aspect of the knee. Frequently medial knee pain is the only symptom. The child will present with decreased internal rotation and weakness of the internal rotators, with the lower extremity occasionally "rolling" into external rotation when person is supine; gait may be antalgic, with the involved extremity(s) held in external rotation. Treatment: surgical fixation of the growth plate is performed using pins or screws. Rehabilitation usually occurs post operatively, and will include range of motion and strengthening exercises, gait training, etc.

Legg-Calve-Perthes Disease (LCP): also known as Idiopathic Juvenile Avascular Necrosis, is found in children, most commonly boys, between four and eight years old. LCP is characterized by avascular necrosis of the femoral head, resulting in a flattening of the femoral head with potential loss of hip range of motion, deformity, and possibly leading to osteoarthritis. Clinical findings: pain which is of insidious onset and intermittent, noted at the anterior groin, medial thigh, and/or medial knee. This pain is more apparent after exertion. There is a noted stiffness of the hip with restriction in internal rotation, and the adductors may be in spasm, limiting abduction. Atrophy of the thigh and buttock musculature may be apparent. LCP is confirmed radiographically. Treatment: the objective of management of LCP is to preserve the sphericity of the femoral head and to preserve/enhance function as much as possible. In early stages of the disease, abduction braces (worn for 6 to 12 months) may achieve this, in later stages, surgery may be indicated.

Congenital Dysplasia of the Hip: this process, which is of unknown etiology, is seen in infants and young children, and occurs 6 to 8 times more frequently in females. Due to a shallowness of the acetabulum, the hip subluxes and/or dislocates. Clinical findings: hip instability is noted along with apparent shortening of the limb due to the femoral head being displaced upward from the acetabulum; in infants, Ortoloni's Sign is positive (a "clunk" is palpated with the following movements: the hip is first adducted and the thigh is depressed to subluxate or dislocate the hip; the thigh is then abducted. The reduction of the displaced hip causes the "clunk" that is felt). In children who are ambulatory, a limp may be noted (with unilateral involvement) or a "waddling" gait (with bilateral involvement). The abductors are usually weakened. Treatment: most neonatal hip instability resolves spontaneously, others require bracing via Pavlik Harness or some other orthoses. Physical therapy may be required for joint approximation exercises and gait training.

Soft Tissue Injuries of the Hip and Pelvis

Bursitis : the bursae are non-contractile/inert structures that normally elicit pain on passive stretching or compression of the hip, however a bursa may also be irritated with resisted tests (Hammer, p. 116). An absolute diagnosis may be difficult to determine without ruling out other structures. Point tenderness over the location of the involved bursa assists with diagnosis (Hammer, p. 116). Tendonitis and Muscle Strains: strains usually occur from excessive tension (force overload) on eccentrically contracted muscle fibers resulting in muscle tearing. The end result is scar tissue and contractures. When the tendinous or tendoperiosteal portion becomes involved because of repetitive overload, tendinitis results. In the lower extremity, muscles spanning two or more joints are the most frequently injured (Hammer, p. 117). Two of the more common muscle strains are: Management: with acute strains, rest, anti-inflammatories, and physical modalities such as ice and pulsed ultrasound; during the subacute phase (2-3 weeks) begin gentle warm up, stretching, resistive exercise, and gradual resumption of activity. At four weeks, begin friction massage followed by resistive exercise emphasizing the injured region of the muscle. Prevention is an important aspect of treating all strains. Assess the mechanism of injury, and educate the patient to alter activities as warranted (Hertling & Kessler, 1996, p. 305).

Dislocations and Fractures of the Hip and Pelvis

Dislocations: are almost always traumatic in nature and involve injury to other soft tissue structures. Posterior hip dislocations occur with hip flexion, adduction, and internal rotation; anterior dislocations occur with slight flexion, abduction, and external rotation. Management: patients usually have some degree of immobilization. During this time you may treat inflammation, perform functional activities while protecting the hip, and maintain strength at the knee, foot, and ankle, as well as of the uninvolved extremity. Depending on the extent of the injury, active isolated motions may begin as early as the second or third week post injury, however the patient determines the extent of movement. After four weeks, the therapist may be more aggressive with exercise and activity prescription. Typically you do not want the patient to perform the combined motions that produced the dislocation until six or seven weeks.

Fractures: can be caused from macrotrauma or repetitive microtrauma, or the fracture may result from a relatively simple movement, as in the case of osteoporotic bone. Fractures of the Femoral Neck: occur primarily in elders and are usually associated with osteoporosis. Forces that produce these fractures are often small, with fractures being caused by twisting the hip while weight bearing, stumbles, or a fall from standing height. The actual fall is often secondary to the fracture. This is the most common hip fracture and occurs in 1 out of 1,000 women over the age of 70. It is an intracapsular fracture and thus normal blood supply is disrupted to the head, which often results in avascular necrosis.

The Garden Stage classification of femoral neck fractures is based on the radiographic appearance of the fracture: In general, the vitality of the person, configuration of the fracture, quality of the bone, and accuracy of reduction influence the type of fixation and outcome. Garden Stage I are the only fractures that may not require surgical fixation. With this fracture, the person is on bed rest for 3 weeks and should perform only mild hip and knee exercise. After 3 weeks sitting and crutch ambulation is allowed, but full weight bearing must be avoided for 8 weeks.

The remaining Garden fractures require surgical intervention if healing is to occur. Because of the high rates of non-union and development of avascular necrosis, most surgeons now perform some type of prosthetic replacement in types III and IV. Type II fractures are typically treated with closed reduction, if possible, or some type of internal fixation.

Intertrochanteric Fractures: occur along a line between the greater and lesser trochanters and are more common among elders and almost always is the result of a fall. Treatment: typically internal fixation via pin and plate; frequently includes the use of intramedullary rods that run through the center of the bone to stabilize the fracture fragments. Failure of the fixation device and mal-union are the most common complications. Weight bearing status is usually touch down weight bearing.

Subtrochanteric Fractures: the least common and most unstable traumatic fracture, also the most difficult to treat because of the height mechanical stresses in this area of the femur. Subtrochanteric fractures are the result of direct trauma of considerable force, and is the most frequent femoral fracture in the younger population. Treatment: usually intramedullary rod or plates, screws, or nails. The Zickle Nail is fairly commonly used. The person is routinely non weightbearing or toe-touch weight bearing for four to six weeks. Straight leg raises are absolutely contraindicated.

Additional femur fractures:

Fractures of the Shaft: similar to fractures of other long bones. Shaft fractures are usually fixated internally via intramedullary (IM) rodding, or via external fixators, such as Hoffman devices. Ilizarov devices are commonly utilized to lengthen the femur if a significant amount of bone is lost.

Intercondylar Fractures: usually the result of longitudinal stresses placed on the femur, such as falls in which the person lands on their feet. Articular surfaces may be involved, depending on the location of the fracture within the condyle(s). Nails, pins, screws, etc. may be used. At times a CPM may be utilized if articular surfaces are involved.

Methods of Stabilization/fracture fixation: The method of internal fixation depends upon the location and severity of the fracture as well as the age and physical condition of the person. Various devices are available for internal fixation, and must be constructed of materials that will be resistant to corrosion in the tissues. Commonly used materials include: surgical grade stainless steel, cobalt chrome, and titanium alloys.

Hip Pinning: multiple threaded pins are applied at varying angles across the fracture site. It may take 3-6 months for the fracture to heal, during which weight bearing is limited or prohibited. Typically the fracture fully heals, unless complicated by an injury to the blood supply, then avascular necrosis or nonunion may result.

Compression Plate: metal plates and screws are used to secure the fracture. At times the metal plate is removed following fracture healing, because the plate alters the normal weight bearing pattern of the bone and increases the potential for future fracture. If the plate is removed, there is a temporary weakening of the bone where the screws were removed, and weight bearing must be limited for a few weeks.

Intramedullary Nail: often used for trochanteric fractures. The IM nail is placed into the endosteal canal of the bone and performs load-sharing duties: which usually permits weight bearing across the fracture site.

Compression Screw-plate: commonly called the Dynamic Hip Screw. This is often used for extracapsular fractures of the proximal femur. The screw grips the femoral head, then slides telescopically into the barrel. Tightening of a screw in the base of the barrel creates compression across the bone fragments. Complications are rare, and usually result from failure of surgical technique rather than failure of the device.

Treatment Guidelines: for people with fractures repaired by internal fixation, goals are to help the person achieve functional independence in their various life roles, with adherence to prescribed weight bearing status, and any precautions associated with the surgery. Gait training is performed utilizing the most appropriate assistive device. Once there is radiographic evidence of healing, most patients are allowed to increase their weight bearing to tolerance.

Pelvic Fractures: are classified as minor or major. Minor fractures involve avulsions and simple bone disruptions, and are routinely not fixated, due to the stable nature of these injuries. Major fractures involve more than one break in the pelvic ring and include displaced sacral injuries, and may involve internal fixation. Major signifies potential pelvic instability or serious associated complications. Treatment includes exercise within the framework of the injury and to patient tolerance, gait training with the most appropriate assistive device and adherence to appropriate weight bearing status.

Evaluation of the Hip and Pelvis

For a fairly complete history and physical examination, refer to pages 291 - 298 of Hertling and Kessler (1996).

The evaluation should be reflective of the general orthopedic evaluation, including a thorough chart review, pertinent history, and physical examination, proceeding from a general approach to a specific approach. Although a person's diagnosis may be specific to the pelvis or hip, it is important that the therapist not be so focused on the pelvis or hip that other areas of involvement may be missed. Once the general evaluation has been performed, then tests specific to the hip and pelvis can be administered.

Differential Diagnosis of the Hip and Pelvis include:
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