New findings in the anatomy of the hip capsule. Its dimensions and thickness and the contribution of the pericapsular structures

In a recent publication in the journal Arthroscopy, the researchers set out to provide a detailed description of the anatomy of the hip capsule and of the pericapsular structures. Dissections were carried out on 11 fresh-frozen cadaveric hips by two independent observers. The researchers recorded the thickness of the capsule, the origin, the insertion and the attachments of the pericapsular structures, including the abductors, rectus femoris, piriformis, the small external rotators and the iliocapsularis muscle. The attachments of the pericapsular muscles were also measured in relation to their size and their distance from reproducible bony landmarks.
The researchers found that the capsule was thickest near its origin on the acetabulum in the posterosuperior and superior quadrants, and thinnest near its attachment on the femur in the posterior and posteroinferior region. The iliocapsularis, the head of rectus femoris, obturator externus, the conjoint tendon and the gluteus minimus tendon showed consistent relationships with the capsule, whereas the piriformis did not appear to have an attachment to the capsule.
The authors of the paper concluded that the dynamic pericapsular structures relevant to hip arthroscopy include the iliocapsularis, the gluteus minimus and the reflected head of rectus femoris. On the acetabulum the thickest region of capsule lies posterosuperiorly and posterolaterally. At the femoral attachment the thickest region lies anteriorly. Knowledge of the complex relationship between the hip capsule and the pericapsular structures presented in this paper may prove useful to surgeons who carry out the specialised and precise capsular incisions required during hip arthroscopy. These findings can contribute valuable information, adding to the recent literature on the importance of capsular management during hip arthroscopy and for the postoperative stability of the joint.