The proximal hip joint capsule and the zona orbicularis contribute to hip joint stability in distraction

Abstract

ABSTRACT:The structure and function of the proximal hip joint capsule and the zona orbicularis are poorly understood. We hypothesized that the zona orbicularis is an important contributor to hip stability in distraction. In seven cadaveric hip specimens from seven male donors we distracted the femur from the acetabulum in a direction parallel to the femoral shaft with the hip in the neutral position. Eight sequential conditions were assessed: (1) intact specimen (muscle and skin removed), (2) capsule vented, (3) incised iliofemoral ligament, (4) circumferentially incised capsule, (5) partially resected capsule (distal to the zona orbicularis), (6) completely resected capsule, (7) radially incised labrum, and (8) completely resected labrum. The reduction of the distraction load was greatest between the partially resected capsule phase and completely resected capsule phase at 1, 3, and 5 mm joint distraction (p ¼ 0.018). The proximal to middle part of the capsule, which includes the zona orbicularis, appears grossly and biomechanically to act as a locking ring wrapping around the neck of the femur and is a key structure for hip stability in distraction. ß

New Findings in Hip Capsular Anatomy: Dimensions of Capsular Thickness and Pericapsular Contributions

“…Several cadaveric and biomechanical studies have described the ligamentous anatomy of the hip capsule and established a foundation for the argument that the static stabilizers of the hip play critical roles in stability, particularly after hip arthroscopy. [5][6][7]13 By use of our data, a greater understanding of these static and dynamic contributors to capsular thickness can be used to facilitate maximal surgical The dynamic capsular stabilizers relevant to the hip arthroscopist include the iliocapsularis, the reflected head of the rectus femoris, and the gluteus minimus. Each of these muscles has direct capsular contributions that are consistent and reproducible.…”

“…[1][2][3] These studies paved the way for later studies that have sought to more clearly define the relation between the dynamic and static contributions of the pericapsular anatomy and hip stability. [4][5][6][7][8] More recently, as hip arthroscopists have performed extensive capsular releases to address various pathologies in the peripheral compartment of the hip, there have been several case reports showing poor outcomes and complications related to postoperative hip instability. 9,10 These case reports suggest that postoperative instability may be related to extensive capsulotomy without repair.…”

“…Currently, research efforts are focused on determining the role the hip capsular ligaments and pericapsular musculature may play in hip stability and understanding how the preservation of their anatomy during hip arthroscopy may contribute to greater postoperative stability. [5][6][7][8]11 It is now clear that an accurate anatomic description of the hip capsule and pericapsular structures is necessary not only to allow surgeons to clearly understand the relations among these structures but also to facilitate analysis of their functional roles in hip stability through biomechanical studies. Correspondingly, the purpose of this study was to provide a detailed description of the anatomy of the hip capsule and pericapsular structures.…”

Femoral cam deformity due to anterior capsular force: A theoretical model with MRI and cadaveric correlation

“…16,17 It is located at the boundary of sphericity of the femoral head 18 and functions to resist distraction of the hip. 19 The iliofemoral ligament is composed of two bands 17 ; the inferior band limits hip extension, 16,20 while the superior band is a checkrein for external rotation in flexion and extension, even when combined with adduction and abduction. 16,17 It is the strongest and stiffest of the hip capsular ligaments.…”

Capsular Ligament Function After Total Hip Arthroplasty

“…Capsule preservation and repair can help to lower dislocation rates 6,7,10,[13][14][15][16][17][18] , and may also maintain the defenses of the native hip against hypermobility, impingement, subluxation, and edge-loading [19][20][21][22] . Preserving a capsular ligament increases surgical complexity: it requires more precise incision, and it limits exposure.…”