Capsular Ligament Function After Total Hip Arthroplasty

Abstract

Background: The hip joint capsule passively restrains extreme range of motion, protecting the native hip against impingement, dislocation, and edge-loading. We hypothesized that following total hip arthroplasty (THA), the reduced femoral head size impairs this protective biomechanical function. Methods: In cadavers, THA was performed through the acetabular medial wall, preserving the entire capsule, and avoiding the targeting of a particular surgical approach. Eight hips were examined. Capsular function was measured by rotating the hip in 5 positions. Three head sizes (28, 32, and 36 mm) with 3 neck lengths (anatomical 0, +5, and +10 mm) were compared. Results: Internal and external rotation range of motion increased following THA, indicating late engagement of the capsule and reduced biomechanical function (p < 0.05). Internal rotation was affected more than external. Increasing neck length reduced this hypermobility, while too much lengthening caused nonphysiological restriction of external rotation. Larger head sizes only slightly reduced hypermobility. Conclusions: Following THA, the capsular ligaments were unable to wrap around the reduced-diameter femoral head to restrain extreme range of motion. The posterior capsule was the most affected, indicating that native posterior capsule preservation is not advantageous, at least in the short term. Insufficient neck length could cause capsular dysfunction even if native ligament anatomy is preserved, while increased neck length could overtighten the anterior capsule. Clinical Relevance: Increased understanding of soft-tissue balancing following THA could help to prevent instability and improve early function. This study illustrates how head size and neck length influence the biomechanical function of the hip capsule in the early postoperative period.

Anatomic evaluation of the insertional footprints of the iliofemoral and ischiofemoral ligaments: a cadaveric study

“…Previous anatomical studies have described the ILFL in detail [9,11,[13][14][15][16]. The present study also investigated the anatomical features of the ILFL, including its origin and size.…”

“…The hip capsule includes three main ligaments, namely, the iliofemoral ligament (ILFL), ischiofemoral ligament (ISFL), and pubofemoral ligament, which form a lining surrounding the hip joint and are thought to stabilize the joint [1][2][3][4][5][6]. Preservation or reconstruction of these capsular ligaments is important in modern hip joint surgeries, such as arthroplasty, arthroscopy, and open surgical procedures [7][8][9][10][11]. In particular, minimally invasive surgery has become a focus in total hip arthroplasty (THA), and preservation of the hip capsule is an important consideration [9][10][11].…”

“…Preservation or reconstruction of these capsular ligaments is important in modern hip joint surgeries, such as arthroplasty, arthroscopy, and open surgical procedures [7][8][9][10][11]. In particular, minimally invasive surgery has become a focus in total hip arthroplasty (THA), and preservation of the hip capsule is an important consideration [9][10][11]. However, iatrogenic instability of the hip due to capsulotomy or poor reconstruction of the capsule during hip arthroscopy remains a problem [7,12] and leads to progression of osteoarthritis in the early postoperative period.…”

“…The literature contains many descriptions of the clinical benefits of preserving the hip capsule [3][4][5][6], including some reports suggesting that preservation of the capsule could have benefits for patients by preserving the defences of the native hip against hypermobility, impingement, subluxation, and edge-loading [5,9,11]. Surgeons performing minimally invasive THA now try to preserve and repair the capsular ligaments as much as possible and have introduced muscle-sparing strategies, including anterior and anterolateral approaches, which are gaining in popularity as methods that facilitate rapid postoperative recovery [17].…”

Hip Joint Capsular Anatomy, Mechanics, and Surgical Management

“…In an effort to characterize capsular function after total hip arthroplasty, van Arkel et al inserted the femoral head, neck, and cup implants through a cotyloid fossa portal and, by doing so, preserved the entire intact joint capsule 77 . The authors reported that the smaller head sizes removed the natural tensioning ability of the capsule to restrain rotational motion (Fig.…”