L‐Capsulotomy and Anatomic Repair of Zona Orbicularis: Hip Arthroscopy Capsular Management for Femoroacetabular Impingement Syndrome

Abstract

As an increasingly recognized technique, the longitudinal outside‐in capsulotomy (LOIC) has the advantages of reducing damage to the iliofemoral ligament and decreasing the impact on hip joint stability. However, it has limitations in exposing and addressing acetabular‐sided lesions, particularly in femoroacetabular impingement syndrome cases with posterior pathologies. In this report, we describe a modified capsulotomy technique based on LOIC to obtain a balance between reducing damage to the iliofemoral ligament and achieving adequate visualization of acetabular‐sided pathologies. Furthermore, the LOIC usually requires transecting the zona orbicularis to expose and address femoral‐sided lesions, but standard repair techniques may be insufficient to adequately restore its anatomic continuity and mechanical strength. In this report, we describe an anatomic suture technique specifically designed for the anatomic repair of the zona orbicularis during LOIC.

Hip arthroscopy is recognized as an effective procedure for managing hip pathologies. The capsulotomy is an important component of hip arthroscopy, with the interportal and T‐capsulotomies being the most popular capsulotomy techniques. However, interportal and T‐capsulotomies usually transect most or even all the medial and lateral arms of the iliofemoral ligament (IFL), which may compromise hip stability. ¹ The longitudinal outside‐in capsulotomy (LOIC) is performed along the longitudinal fibers of the IFL, thereby reducing transverse incision of the ligament, but it may not provide sufficient exposure for acetabular‐sided pathologies, especially in patients with femoroacetabular impingement syndrome accompanied by posterior overcoverage. ² To reconcile the imperative of preserving hip stability with the requirement for adequate visualization, we propose the L‐capsulotomy. By extending the proximal incision of the LOIC laterally, this technique selectively releases the lateral arm while sparing the medial arm of the IFL.

The zona orbicularis (ZO) is described as a locking ring around the femoral neck and helps to form the hip suction seal that is essential for maintaining distractive stability. ³ During LOIC, the ZO is often transected to gain access to femoral‐sided pathologies. However, few studies have emphasized the anatomic repair of this structure, and the conventional side‐to‐side suture technique may not adequately restore its biomechanical function. Consequently, we describe an anatomic repair technique using high‐strength sutures to restore the continuity and functional integrity of the ZO.

SURGICAL TECHNIQUE

Preoperative Evaluation

A thorough preoperative evaluation is mandatory, including a review of the patient's general health, past medical, and surgical history. The physical examination emphasizes the hip range of motion and primary physical examination, including flexion‐adduction‐internal rotation, flexion‐abduction‐external rotation tests, and the Beighton Score. A comprehensive imaging assessment is essential for surgical planning, which includes an anteroposterior view of the pelvis, Dunn's view, and the false profile view to evaluate acetabular coverage and femoral head deformity. Three‐dimensional computed tomography provides detailed visualization of cam deformities and the morphology of the anterior inferior iliac spine. Magnetic resonance imaging is used to assess labral and ligamentum teres pathologies and to characterize the anterior joint capsule.

Surgical Process

Anesthesia and Positioning

Following the induction of general anesthesia, the patient is positioned supine on a traction table. The operative limb is maintained in neutral abduction and adduction with 10° of flexion, while the nonoperative limb is positioned in about 40° of abduction.

LOIC and Management of Pathologies

Three standard portals are established: the anterolateral, mid‐anterior, and distal anterolateral accessory portals. Consistent with the previous report, ⁴ the LOIC is performed using a radiofrequency probe (Smith & Nephew, Andover, MA) to release the capsule (Figure 1A,D). After the capsulotomy, gradual traction is applied to achieve a joint distraction of approximately 10 mm. Diagnostic arthroscopy of the central compartment is then initiated to evaluate and treat the chondrolabral lesions, ligamentum teres tears, and pathologies of the acetabulum (Figure 2A).

FIGURE 1.

Arthroscopic views of the right hip in the supine position show the L‐capsulotomy, as viewed from the AL portal using a 30° arthroscope. (A) Performing the LOIC. (B) Transverse incision made laterally to the longitudinal incision along the acetabular rim. (C) Enlarged view of the L‐capsulotomy. (D‐F) The schematic diagram of the right hip shows the main procedures of L‐capsulotomy. (A, acetabulum; C, capsule; FH, femoral head; IH, indirect head of the rectus femoris; IFL, iliofemoral ligament; L, labrum; LOIC, longitudinal outside‐in capsulotomy; ZO, zona orbicularis.)

FIGURE 2.

Arthroscopic views of the right hip in the supine position show the management of intra‐articular lesions from the AL portal using a 30° arthroscope. (A) Labrum repair. (B) Cam osteoplasty. (FH, femoral head; L, labrum.)

L‐Capsulotomy

If there is restricted visualization or instrument maneuverability, the deep layer of the joint capsule could be released first, and the longitudinal incision could be converted to an L incision if the capsule release still fails to provide adequate access. The transverse incision is made along the edge of the acetabulum, lateral to the proximal end of the longitudinal incision (Figure 1B,C,E, and F). The length of the incision is determined by the extent of the labral injury and is about 1 cm in most conditions, and it could be extended in cases such as posterior labral injury or excessive posterior acetabular coverage. During the transverse incision, in accordance with the principle of preserving the capsule and ensuring adequate exposure, the deep synovial layer of the capsule is released while the superficial layer is preserved. Once traction is released, the hip is flexed from 30° to 60° to induce laxity in the anterior capsule and expand the peripheral working space to perform cam‐plasty (Figure 2B).

Capsule Closure

The ZO is identified under arthroscopy. A suture hook (Star Medical, Beijing, China) with PDS‐II (Ethicon, Somerville, NJ) is used for subsequent capsular closure. First, each flap of the capsule is penetrated with the hook at the upper and lower margins of the ZO. Then, the ends of the sutures are retrieved to the outer surface of the capsule. Finally, the high‐strength sutures (Delta Medical, Beijing, China) are passed through the lateral and medial sides of the capsule at the level of the ZO, and the sutures are tied to complete the anatomic repair of the ZO. For the proximal incision, the suture is first passed through the medial and lateral sides of the capsule at the longitudinal incision, then the suture is passed from bottom to top through the proximal side of the capsule at the transverse incision. Finally, the suture is tightened and knotted to close the capsule (Figure 3). For the detailed procedure, refer to Video 1.

FIGURE 3.

Arthroscopic views of the left hip in the supine position show the procedures of capsular closure from the AL portal using a 30° arthroscope. (A) Identification of the ZO under arthroscopy. (B) Pass the PDS‐II through the upper and lower margins of the ZO. (C) Pass the high‐strength sutures through the upper and lower margins of the ZO. (D‐E) Anatomic repair of the ZO. (F‐G) The schematic diagram of the right hip shows the main procedures of capsular closure. (C, capsule; FN, femoral neck; FH, femoral head; IH, indirect head of the rectus femoris; IFL, iliofemoral ligament; L, labrum; ZO, zona orbicularis.)

VIDEO 1.

Download video file ^{(79.7MB, mp4)}

The patient was in the supine position, right hip. Viewing was performed through the anterolateral portal using a 30° arthroscope. The L‐capsulotomy is based on the longitudinal outside‐in capsulotomy. After the longitudinal outside‐in capsulotomy, traction is applied and diagnostic arthroscopy of the central compartment is then initiated to evaluate and treat the chondrolabral lesions and pathologies of the acetabulum. If visualization is restricted, the longitudinal incision could be converted to an L incision. The transverse incision is made along the edge of the acetabulum, lateral to the proximal end of the longitudinal incision. During the transverse incision, the deep synovial layer of the capsule is released while the superficial layer is preserved. For capsular closure, the zona orbicularis (ZO) is identified under arthroscopy. First, each flap of the capsule is penetrated with the suture hook at the upper and lower margins of the ZO. Then, the ends of the sutures are retrieved to the outer surface of the capsule. Finally, the high‐strength sutures are passed through the lateral and medial sides of the capsule at the level of the ZO, and the sutures are tied to complete the anatomic repair of the ZO. For the proximal incision, the suture is first passed through the medial and lateral sides of the capsule at the longitudinal incision, then the suture is passed from bottom to top through the proximal side of the capsule at the transverse incision. Finally, the suture is tightened and knotted to close the capsule. Video content can be viewed at https://doi.org/10.1002/atn2.70149.

Postoperative Rehabilitation

Medication for analgesia and prophylaxis of heterotopic ossification is prescribed for 4 weeks postoperatively. The flexion of the hip is limited from 0° to 90°, and extreme abduction and external rotation are avoided for 2 weeks. Weight‐bearing is restricted with crutches for 3 to 4 weeks.

DISCUSSION

The rationale for the L‐capsulotomy, selectively transecting the lateral arm of the IFL while preserving the medial arm, is based on both biomechanical and clinical considerations. Biomechanically, the medial arm of the IFL acts as a primary restraint against internal rotation in extension and anterior translation of the femoral head. Compromise of this structure is a recognized etiology of iatrogenic anterior hip instability, even in patients with adequate anterior acetabular coverage. From a clinical perspective, labral tears are most prevalent in the 11‐ to 2‐o'clock positions. ⁵ A LOIC directed toward the 1‐o'clock position could facilitate adequate visualization and management of pathologies within this region. Through capsular release and partial reduction of traction to reduce capsular tension, the instruments could access the 2‐ to 3‐o'clock position without necessitating transection of the medial arm. However, for pathologies located at the 11‐o'clock position or extending posteriorly in patients with femoroacetabular impingement syndrome, the longitudinal incision may not provide adequate access to this region. Consequently, transection of the lateral arm of the IFL is required to address the posterior pathologies.

The ZO is a structure that may not be fully emphasized in clinical practice but plays a crucial role in maintaining distraction and rotational stability. Existing evidence suggests that the integrity and presence of the ZO are critical for maintaining hip joint stability, and the disruption of this structure could significantly compromise hip distraction stability. ⁶ Therefore, the anatomic restoration of the ZO should be considered an integral component of capsular management. Despite these findings, there is a paucity of literature regarding anatomic restoration of the ZO, with current techniques largely limited to side‐to‐side repair. To address this limitation, we describe an anatomic suture technique specifically for the ZO. Intraoperatively, the ZO is first identified on the inner surface of the capsule and is tightly sutured using high‐strength sutures in the upper and lower margins of the ZO separately, which could re‐establish its native structure and mechanical function. This approach ensures anatomic repair of the key stabilizing structure while optimizing surgical efficiency. This technique does have some limitations, including a requirement for precise identification of extracapsular anatomy, restricted manipulation in cases with thickened or fibrotic capsules, etc. Table 1 details the Pearls and Pitfalls of our technique. The advantages and disadvantages of our technique are detailed in Table 2.

TABLE 1.

Pearls and Pitfalls of L‐Capsulotomy and Anatomic Repair of Zona Orbicularis

Pearls	Pitfalls
• Use of the longitudinal outside‐in capsulotomy • Restriction of the extent of the transverse incision • Use of curved or adjustable equipment • Emphasis on zona orbicularis restoration	• Incorrect positioning of the longitudinal outside‐in capsulotomy • Too proximally or too distally of the transverse incision • Excessive use of radiofrequency or over‐resection of the capsule

TABLE 2.

Advantages and Disadvantages of L‐Capsulotomy and Anatomic Repair of Zona Orbicularis

Advantages	Disadvantages
• Improved arthroscopic visualization and instrument working space compared with a simple longitudinal outside‐in capsulotomy • Reduced capsular disruption compared with T‐capsulotomy • A biomechanically superior and anatomic zona orbicularis repair • Simplification of the suturing procedure due to the short transverse incision	• Requirement for precise identification of extracapsular anatomy • Limitations in addressing the extreme anterior and posterior labrum in cases of acetabular overcoverage • Restricted manipulation in cases with thickened or fibrotic capsules

DISCLOSURES

The authors (S‐Y.S., X‐X.L., Y.L., C‐B.L., Q‐F.Y.) declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

FUNDING

This research was supported by the Science Foundation of The Second Hospital of Shandong University (2023JX15).