greater and lesser trochanters is an osseous ridge, which serves as the site of attachment of the short external rotators. The lesser trochanter is the site of attachment of the iliopsosas tendon. This exits the pelvis over the anterior column and superior pubic ramus and then travels over the anterior femoral neck to insert on the lesser trochanter, which lies on the posterior inferior aspect of the intertrochanteric ridge. Within the proximal femur and femoral neck is a large and dense tra­beculation known as the calcar. The calcar pro­vides increased strength to the proximal femur. Frequently the proximal posteromedial femur from the base of the femoral neck including the lesser trochanter is also referred to as the calcar. If the medial calcar region of the proximal femur is a separate fragment of a proximal femur frac­ture, the fracture is considered unstable.

the decits seen in an isolated injury to the com­mon peroneal nerve injury at the level of the bu­lar neck. One anatomic point with important clinical relevance is that the peroneal division of the sciatic nerve has only one motor branch in the posterior thigh supplying the short head of the biceps femoris. Determining if the short head of the biceps is normally innervated can assist in determining the level of peroneal nerve injury clinically (i.e., the hip or knee).

The medial and lateral femoral circumex ves­sels in conjunction with the artery of the ligamen­tum teres provide the vascular supply to proximal femur and femoral head (Fig.13.6). The medial femoral circumex artery, which is the dominant supply of the femoral head, extends posteriorly and ascends proximally deep to the quadratus femoris muscle. At the level of the hip, it joins an arterial ring at the base of the femoral neck. The lateral femoral circumex artery extends anteri­orly and gives off an ascending branch, which also joins the arterial ring at the base of the femo-

The joint reaction force is the sum of all forces that cross a joint. This includes components from gravity, body weight, and muscle forces acting upon the joint. In two-legged stance with both feet on the ground and static conditions, a joint reaction force of approximately 1.3–1.5 times body weight will cross each hip joint. However, in single limb stance, this force will increase to

with heel strike and continues until the next heel strike of the same leg. Gait can be divided into two principle phases: stance and swing. The stance phase is dened as that portion of the gait cycle when the foot is in contact with the ground. The swing phase is therefore the portion of each step when the foot is not in contact with the ground. The stance phase makes up 60% of each step, with the remainder being made up by the swing phase. Therefore, in 20% of the gait cycle, both feet are in contact with the ground. Normal gait requires a stable pelvis, which is provided by the hip abductor muscles. Normal gait also requires 40° of hip exion and 10° of internal rotation and external rotation.

The evaluation of a patient with hip pain requires careful attention to the history, physical examina­tion, and radiographic studies. The character, nature, and duration of the patient’s pain should be documented. Acute or recent onset pain will more commonly be associated with trauma or infection. Chronic and gradually progressive pain is associated with arthritic conditions. Intra­articular pain is usually described as a deep, ach­ing pain. Pain from the hip joint will commonly be noted anteriorly in the groin or posterior to the greater trochanter. Hip pain can radiate down the inner and anterior thigh to the knee with little or no pain in the area of the hip. Only rarely will hip pain radiate distal to the knee. In adolescent patients, it is not uncommon for hip pathology to present as knee pain. Therefore, a thorough phys­ical and radiographic evaluation of the hips is necessary to identify the pathology in these patients. Posterior pain and buttock pain is more commonly associated with lumbar spine pathol­ogy. Spine pain also will more commonly radiate down the posterior thigh and below the knee.

The most important aspect of the physical exam in patients with hip disease is to evaluate their gait pattern. This will reveal important informa­tion about the patient’s ambulatory status and their pain. Patients with signicant hip pain will manifest a coxalgic gait. This gait pattern is rep­resented by a reduced stance phase on the painful leg and the shoulders lurch laterally over the affected hip. Patients with mild pain or weakness