Hip Arthroscopy: Anatomy and Access to the Peripheral Compartment

John P. Salvo

Hip arthroscopy is an evolving field within orthopedic surgery. When compared to knee arthroscopy and shoulder arthroscopy, hip arthroscopy is in its infancy. Much like the evolution of knee arthroscopy in the 1970s and shoulder arthroscopy in the 1980s, there were limitations with understanding of hip arthroscopic anatomy, pathology, and techniques in the early stages. There has been a surge in technological developments since the mid 1990s, allowing surgeons to reliably treat a variety of painful hip conditions arthroscopically. With advances in diagnostic capabilities, specialized equipment, and increased awareness of hip pathology and mechanics, the number of arthroscopic procedures performed annually has increased exponentially. The development of advanced imaging technologies, particularly magnetic resonance image (MRI), has improved visualization of intra-articular anatomy allowing more accurate diagnosis and subsequent surgical treatments.

Hip arthroscopy was first introduced by Takagi in 1939 and has rapidly emerged as an excellent procedure for hip pathology in the last few decades. Hip arthroscopy gained limited popularity in the 1980s and 1990s and has had exponential growth since 2000.

Arthroscopically, the hip is divided into three areas: central compartment, peripheral compartment, and peritrochanteric space (1,2,3,4). This chapter will review relevant arthroscopic anatomy and discuss access to and procedures performed in the peripheral compartment.

Anatomy

When discussing arthroscopic anatomy, there are three compartments in and around the hip joint (1,3,4,5,6,7,8,9,10). The central compartment consists of the formal articulation of the femoral head and the acetabulum. Important structures in this compartment include the labrum, articular cartilage (femoral and acetabular), ligamentum teres, pulvinar, and transverse acetabular ligament. The peripheral compartment is extra-articular but intracapsular and includes the junction of the femoral head cartilage with the periosteum and runs distal to capsular insertion at the intertrochanteric line. Important structures include the medial and lateral synovial folds, the zona orbicularis, and the femoral neck. The lateral retinacular vessels are often visible from the peripheral compartment and are an important arthroscopic landmark. The peritrochanteric space consists of the lateral femur, intertrochanteric ridge, trochanteric bursa, gluteus medius and minimus tendons, vastus lateralis origin, gluteus maximus tendon, and iliotibial band.

The acetabular labrum deepens the bony socket and increases the femoral head coverage (1,7,11,12). The labrum is comprised primarily of fibrocartilage and has peripheral vascular supply from the capsule, synovium, and acetabulum. The vascular supply penetrates to approximately the peripheral one-third of the labrum (2). The labrum is attached to the outer perimeter of the acetabulum in a nearly continuous fashion with attachments to the transverse acetabular ligament anteriorly and posteriorly (13). Innervation of the labrum has also been confirmed with identification of free nerve endings and receptors including Pacini and Ruffini corpuscles allowing for nociceptor and proprioceptor feedback (14). In addition to the mechanical stability that the labrum contributes to the hip, it also acts to “seal” the joint and prevent extravasation of synovial fluid and thus maintain negative intra-articular pressure (aka “suction-seal”). This sealing process contributes to increased stability and additional protection of the articular cartilage (11).

The ligamentum teres is a double bundle structure consisting of both anterior and posterior bundle that runs from the fovea to the acetabular fossa near to the transverse acetabular ligament. It has been suggested that the ligamentum may act as a secondary stabilizer to the hip in the event of a labral injury or hip dysplasia (15).

Indications

Indications for hip arthroscopy include labral tears, loose bodies, femoroacetabular impingement (FAI), synovial disease (e.g., PVNS), chondral injuries, internal or external snapping hip (coxa saltans), early degenerative arthritis, and septic arthritis (1,3,4,5,6,7,10,15,16,17,18). Peritrochanteric pathology such as chronic trochanteric bursitis, gluteus medius
and minimus tendinosis and tears, external snapping hip are amenable to arthroscopic correction as well.

Surgical Technique

Because the hip is a constrained ball and socket joint it requires distraction for safe entry and performance of arthroscopic procedures (1,3,4,5,6,7,8,9,10,16,17). To that end fluoroscopy is necessary to ensure safe entry and appropriate portal placement as well as specialized tables and curved and flexible instruments to allow safe work within and around the hip joint.

This equipment is essential to minimize the risk of iatrogenic injury and maximize what the skilled hip arthroscopist can accomplish.