The proximal femur consists of a femoral head and neck as well as a greater and lesser trochanter (Fig. 18–1). The hip joint is a ball and socket joint composed of the head of the femur and the acetabulum. This articulation has many palpable bony landmarks. The anterosuperior iliac spine and the greater trochanter are easily palpated laterally, and the pubic symphysis and the tubercle (lying 1 inch lateral to the symphysis) are palpated medially. The hip joint is capable of a very wide range of motion.
The neck-shaft angle should be evaluated in all suspected fractures. Normal is 120 to 130 degrees.
The joint is enclosed in a capsule that has attachments to the rim of the acetabulum and the femoral neck. Three ligaments are formed by capsular thickenings: the iliofemoral ligament, which is located anteriorly and is the thickest and the strongest of the three; the pubofemoral ligament, which is located inferiorly; and the ischiofemoral ligament, which is located posteriorly and is the widest of the three ligaments. The iliofemoral ligament is divided into two bands, a lower band that passes obliquely downward and an upper band. This ligament tightens when the hip is extended. Additional support is provided by the labrum acetabulare, which is a thick band of cartilage surrounding and extending out from the acetabulum adding depth to the cavity. A flat, thin-shaped ligament, the ligament teres, attaches the head of the femur to the acetabulum centrally.
The muscles surrounding the hip joint are massive and powerful and significantly contribute to the forces acting on the head of the femur. They can be divided into three main groups—anterior, medial, and posterior. The anterior muscles include the iliopsoas, tensor fasciae latae, sartorius, and quadriceps femoris. Muscles within the medial compartment include the pectineus, gracilis, obturator externus, and adductor magnus, brevis, and longus. The main action of the medial muscles is adduction of the thigh. Posterior muscles include the semitendinosus, semimembranosus, and biceps femoris. The posterior muscles function to extend the hip.
It is essential that one clearly understands the precarious vascular supply to the proximal femur. The vascular anatomy consists of three main sources, listed in order of importance (Fig. 18–2).
Femoral circumflex and retinacular arteries
Vessel of the ligamentum teres
The vascular ring around the base of the femoral neck sends intracapsular vessels (retinacular vessels) that are important in maintaining perfusion to the femoral head.
The femoral circumflex arteries surround the base of the femoral neck and give rise to retinacular arteries that ascend up to supply the femoral head. Disruption of the retinacular blood vessels results in avascular necrosis (AVN) of ...