Placement of portals and maneuverability of the arthroscope and instruments within the hip joint are more difficult than in other joints. This difficulty is related to various anatomic features: a thick soft tissue mantle, close proximity of two major neurovas-cular bundles, a strong articular capsule, a relatively small intraarticular volume, permanent contact of the articular surfaces, and the sealing of the deep, central part of the joint by the acetabular labrum. Thus, if no traction is applied to the hip, only a small film of synovial fluid separates the articular surface of the femoral head from the lunate cartilage and acetabular labrum (artificial space).
The anatomy of the acetabular labrum must be considered when accessing the hip joint. The labrum seals the joint space between the lunate cartilage and the femoral head. Even under complete muscle relaxation during anesthesia, the labrum maintains a vacuum force of about 120 to 200 N, which keeps the femoral head within the socket.45-47 To overcome the vacuum force and passive resistance of the soft tissues, traction is needed to separate the head from the socket, to elevate the labrum from the head, and to allow the arthroscope and other instruments access to the narrow artificial space between the weight-bearing cartilage of the femoral head and acetabulum. However, if traction is applied, the joint capsule with the iliofemoral, ischiofemoral, and pubofemoral ligaments is tensioned and the joint space peripheral to the acetabular labrum decreases. Thus, to maintain the space of the peripheral hip joint cavity for better visibility and maneuverability during arthroscopy, traction should be avoided.
In consequence, Dorfmann and Boyer11,13 divided the hip arthroscopically into two compartments separated by the labrum (Figure 11.1). The first is the central compartment, comprising the lunate cartilage, the acetabular fossa, the ligamentum teres, and the loaded articular surface of the femoral head. This part of the joint can be visualized almost exclusively with traction. The second is the peripheral compartment, consisting of the unloaded cartilage of the femoral head, the femoral neck with the medial, anterior, and lateral synovial folds (Weitbrecht's ligaments), and the articular capsule with its intrinsic ligaments including the zona orbicularis. This area can be seen without traction and is described subsequently here.43
The placement of personnel and equipment for HA without traction does not differ from the general HA setup (Figure 11.2). Surgeon, assistant, and scrub nurse
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