All-Arthroscopic Reconstruction of the Acetabular Labrum by Capsular Augmentation

Abstract

The acetabular labrum plays an important role in hip joint stability and articular cartilage maintenance. As such, reconstitution of the labral complex is ideal. In cases in which the labrum is too degenerative to allow adequate reconstruction with current repair techniques, a capsular augmentation is a novel technique that can be used to restore the labral structure. Use of capsular augmentation enables preservation of the donor-tissue blood supply with local tissue transfer, without adding significant complexity to the procedure or significant donor-site morbidity.

The labrum of the hip plays an integral role in preserving hip joint stability and maintaining the articular cartilage.¹ Increasing attention has been paid to labral repair and preservation, with some authors suggesting that the outcome after hip arthroscopy is directly related to whether the labrum is preserved.² Cadaveric studies have proposed that the hip labrum provides a “fluid seal effect.”³ By providing a fluid seal, the labrum is thought to prevent loss of synovial fluid from the central compartment, thereby protecting the articular cartilage and minimizing the risk of osteoarthritis. Given the biomechanical properties of the hip labrum, labral preservation and reconstruction are preferred over partial labral resection for the treatment of acetabular labral tears, regardless of the presence of femoroacetabular impingement.^4-6

Although most surgeons prefer to repair the torn labrum, in certain cases primary labral repair can be challenging. During arthroscopy, the labrum can be found to be hypoplastic or to have a complex tear, leaving insufficient tissue with which to perform a repair. Prior work on the topic has suggested the use of a variety of tissue grafts suitable to reconstruct the labrum.^7,8 We present a novel technique for reconstruction of the hypoplastic and/or degenerative acetabular labrum using the hip capsule (Fig 1).

Fig 1.

Flow diagram for labral augmentation using adjacent capsular tissue.

Technique

Take the patient to the operating room, and position the patient supine on the hip distraction table (Smith & Nephew, Andover, MA). Administer general anesthesia through general endotracheal tube intubation. Carefully reposition the patient against a silicone gel–padded perineal post, and secure the feet into well-padded distraction boots. After complete muscular paralysis and with fluoroscopic guidance, establish safe arthroscopic access into the central compartment through the anterolateral portal. Subsequently, establish the anterior, midanterior, and Dienst portals under direct arthroscopic visualization.

Once all the working portals have been established through puncture capsulotomy, perform diagnostic arthroscopy to confirm the presence and degree of labral pathology, as well as concomitant damage to the articular cartilage, most notably the chondrolabral junction. In cases in which the labrum is observed to be irreparable because of hypoplasticity (width <5 mm), complex tearing, or frank degeneration of native tissue (Fig 2), capsular augmentation should be performed to restore functional labral anatomy (Video 1, Table 1).

Fig 2.

Severely damaged labral tissue (arrow), not amenable to repair by conventional methods, and associated chondrolabral disruption with chondral flap (asterisk).

Table 1.

Equipment and Indications for Performing Labral Reconstruction With Capsular Augmentation

Procedural Aspect	Description
Equipment	Supine hip positioning table Fluoroscopy equipment 17-gauge cannulated needle High-speed arthroscopic burr 70° video arthroscope Knife rasp Suture grasper 2.3-mm bioabsorbable anchors Hip cannula and obturator set (4.5, 5.0, or 5.5 mm in diameter)
Indications	Hypoplastic labrum Degenerative labrum Complex tear pattern precluding repair Adequate capsular tissue

To perform this technique, first insert a knife rasp through the Dienst portal while viewing from the anterolateral or midanterior portal. Position the rasp at the capsular reflection, approximately 5 to 10 mm above the region of the labrum that is to be augmented. The amount of capsular tissue to be elevated is dependent on how much will be needed to refortify the damaged labrum into a structure capable of holding suture and forming a fluid seal with the femoral head when traction is released; more capsular tissue is required when the labral remnant is severely frayed and degenerative. Next, use the knife rasp to elevate capsular tissue off the acetabular shelf. Meticulous technique with gentle maneuvering aids in preserving continuity of the capsulolabral blood supply (Fig 3). In the setting of femoroacetabular impingement, acetabular recession is performed using a chondrolabral junction–preserving technique.⁹

Fig 3.

Capsular elevation is performed with a knife rasp through the Dienst portal. Elevation of the capsular tissue (arrow) shows an underlying pincer lesion (asterisk).

In brief, perform acetabular recession through the Dienst or midanterior portal with a 4-mm round abrader. Use the burr in reverse mode so that the labrum and surrounding capsule are not grasped or mutilated during acetabular osteoplasty. It helps to set the burr at high speed (8,000 revolutions per minute); this will achieve a more precise cut and limit the chance of inexact over-recession caused by large bony fragmentation due to torque that can occur at lower burr speeds. Take great care to preserve the chondrolabral junction when it is intact. While the acetabulum is being recessed, the burr can be used all the way down to the chondro-osseous interface without violating or perforating the chondrolabral junction because of the significant plasticity of this tissue. Use both direct visualization through working portals and fluoroscopic imaging to confirm adequate recession.

Now that the acetabular rim has been prepared, anatomic labral reconstruction with the previously elevated capsular tissue can begin. Bring the elevated capsular tissue together with the remaining labral tissue and secure at the acetabular rim using 2.3-mm bioabsorbable composite anchors placed through the midanterior portal with a 5.5-mm cannula (Fig 4). Use fluoroscopy to verify correct placement and orientation of the anchors. It is important to place anchors 1 cm apart so that the capsular vessels are not strangulated.

Fig 4.

Looped suture construct (asterisk) bringing together elevated capsule (double arrows) and remaining labral tissue (single arrow).

Secure the reconstructed labrum with a loop suture construct. Achieve this by sending a single suture tail through the anterior or Dienst portal. Next, pierce the chondrolabral complex with a modified 17-gauge needle with a wire suture shuttle relay. Use a suture grasper to bring the other free suture tail through the chondrolabral complex using the suture relay. Finally, bring the suture tail through the anterior or Dienst portal in preparation for knot tying.

Use intermittent traction while securing the newly augmented labrum with a Weston knot and multiple half-hitches placed along the capsular aspect of the repair (Fig 5). Dynamic tensioning of the knot with concurrent release of traction (until joint reduction occurs) prevents labral eversion and formation of an “out-of-round” repair. An “out-of-round” repair is one that does not restore contact between the articular surface of the labrum and corresponding femoral head when the joint is fully reduced. Concurrent use of intermittent traction release and dynamic suture tensioning ensures an anatomic or “in-round” repair that promotes the functional ability of the newly reconstructed labrum to provide a fluid seal against the femoral head.

Fig 5.

Completed labral reconstruction by capsular augmentation (arrow) and chondral flap (asterisk).

It has been our experience that chondrolabral disruption in the form of a chondral flap is present in many patients requiring capsular augmentation. In addition, there is evidence that supports the viability of chondrocytes within these flaps.¹⁰ Therefore, when a full-thickness flap is encountered, microfracture the acetabular shelf beneath the chondral flap using a Steadman awl to enhance re-annealing of the delaminated cartilage to the acetabulum (Fig 6). When a partial-thickness flap is seen, bring suture through the substance of the flap to reapproximate the disrupted cartilage to its native footprint.

Fig 6.

Preservation of and microfracture beneath chondral flap.

After proper tensioning, seating, and tie-down, release the remaining traction and directly visualize the peripheral compartment to confirm an adequate labral reconstruction that provides a fluid seal. To test for functional impingement, put the hip through a simple range of motion to confirm and/or identify any abnormalities of the femoral neck that collide with the labrum. If an impinging cam lesion is present, resect it with a 5.0-mm round abrader on a high-speed setting. Do not proximally overextend this resection because doing so can create a “step-off” that disrupts the fluid seal in extremes of motion.

Postoperatively, patients are allowed immediate weight bearing as tolerated using a flat-foot gait with crutches. This type of gait is used to keep the pelvis level during the stance phase to prevent antalgic lurching of the pelvis, which may stress the reconstruction. At 6 weeks postoperatively, crutches are no longer required and patients start using a stationary bike or elliptical trainer with light resistance. At 3 months, they are allowed swimming with heavy kicking. Four months after reconstruction, golfing is permissible. Finally, 6 months postoperatively, patients can resume impact-loading exercises as tolerated.

Discussion

We present an all-arthroscopic surgical technique for reconstructing the acetabular labrum using the hip joint capsule. This technique allows the hip arthroscopist to repair a degenerative labrum and re-create a tight seal with local autologous graft. There is convincing evidence in the literature that the acetabular labrum plays an important role in hip joint stability and articular cartilage maintenance. As such, reconstitution of the labral complex is preferred whenever possible. In the event that the labrum has insufficient healthy tissue to allow adequate healing with restoration of the blood supply, a capsular augmentation is a successful technique in our hands.

Labral reconstruction using autograft or allograft donor tissue is a proposed alternative for reconstituting deficient labral tissue, with good to excellent early results reported in the literature.¹¹ However, the transfer of the grafts arthroscopically is technically challenging and requires tissue metaplasia with ingrowth of the blood supply. In addition, there is donor-site morbidity at the extra-articular graft site.

Our capsular augmentation technique provides the benefits of donor-site morbidity minimization, application of local tissue with an intact blood supply, and an easier surgical technique as compared with conventional labral reconstruction (Table 2). When performed correctly, it ensures an “in-round” repair, whereas one of the difficulties with remote grafts is obtaining the proper graft length and position to ensure an in-round repair with recapitulation of the native labral seal. A limitation of our technique is that the role of the hip capsule is unclear and this structure could potentially play a role in hip stability. This technique has not been tested biomechanically, and our good to excellent results are preliminary.

Table 2.

Proposed Strengths and Weaknesses of Capsular Augmentation Technique

Technique strengths

Preserves donor-tissue blood supply

Avoids significant donor-site morbidity

Does not add significant complexity to procedure

Technique weaknesses

May affect capsular stability

Needs longer follow-up and biomechanical testing

May not be suitable for reconstruction of large segmental labral defects

Supplementary Data

Video 1

Acetabular labrum reconstruction using local capsular tissue with blood supply preservation. This technique is performed in the setting of labral damage that is unable to be repaired. The goal of capsular augmentation is to restore the labrum's structure-function relation.