Arthroscopic Fixation of Minimally Displaced Avulsion Fracture of Ischial Tuberosity Using a "Double-Pulley" Suture Anchor Technique

Abstract

Avulsion fracture of the ischial tuberosity is an uncommon injury caused by a sudden, forceful eccentric contraction of the hamstrings that avulses the unfused secondary ossification center from the pelvis. Although open reduction and internal fixation are recommended when fragment displacement exceeds 2 cm, reports describing minimally invasive solutions are still lacking. In addition, for those patients who are engaged in high-intensity sports or physical activities, conservative treatment can compromise hamstring power, delay return to sport, and occasionally result in chronic ischial pain. To address these limitations, we describe an arthroscopic "double-pulley" suture anchor fixation technique for avulsion fracture of the ischial tuberosity with 6-mm displacement. This approach reduces soft tissue trauma through minimally invasive access and avoids secondary surgeries for implant removal, potentially reducing recovery time and improving patient outcomes.

Avulsion fracture of the ischial tuberosity (AFIT) occurs when a sudden, forceful eccentric contraction of the hamstrings pulls part of the unfused secondary ossification center off the pelvis.¹ Conservative treatments, including analgesics, restricted activities, and partial weight-bearing with crutches, are widely favored for managing avulsion fractures.² Surgical interventions are recommended for those patients with displacement more than 2 cm to realign the anatomy and restore hip functionality.³ At present, disagreement exists regarding the optimal treatment for AFIT, especially for those patients with displacement less than 2 cm^4,5 For those patients with bone displacement less than 2 cm but who are engaged in high-intensity sports or physical activities, conservative treatment methods might potentially impair their athletic performance. Here, we introduce a novel approach to AFIT management, using a arthroscopic double-pulley suture anchor technique that achieves anatomic reduction and secure fixation of the avulsed fragment while preserving surrounding soft tissue. We hope that this minimally invasive technology can be applied to patients with AFIT and fracture fragment displacement less than 2 cm, so as to help them restore better performance.

Patient Evaluation and Indications

This technique is indicated for patients with bone displacement less than 2 cm. Indications and contraindications are summarized in Table 1. This research is supervised by the local institutional review board at the Second Xiangya Hospital of Central South University. The authors obtained the written consent of the patient for the publication of the data and images that appear in this article.

Table 1.

Indications and Contraindications

Indications	Contraindications
Patients with displacement <2 cm who are engaged in high-intensity sports or physical activities.	Significant displacement (>2 cm) of fracture fragments.
Active individuals requiring early rehabilitation and rapid return to functional activities.	Severe nonunion or complex anatomical variations (eg, extensive fibrosis, heterotopic ossification).
Cases in whom conservative treatment fails to alleviate symptoms (eg, persistent pain, delayed recovery).	Lack of surgeon expertise in arthroscopic techniques or image-guided navigation.
	Concomitant injuries requiring open reduction or additional bony procedures.

Surgical Technique

Patient Positioning and Preparation

Under general anesthesia, the patient is positioned prone, and the course of the sciatic nerve is meticulously mapped out. A 2.0-mm Kirschner wire (AR-8945K, Arthrex, Inc., Naples, FL) is then used to pinpoint the location of the right ischial tubercle accurately (Fig 1).

Fig 1.

Preoperative radiologic assessments and skin marks. Plain radiograph (A), computed tomography (B), magnetic resonance imaging (C), and 3-dimensional reconstruction (D) demonstrated AFIT with a 5-mm displaced bony fragment on the right ischial tubercle (yellow arrows). Regional edema was observed on magnetic resonance imaging at the right ischial tuberosity, and the proximal footprint of hamstring tendon of each side was intact. The patient was placed in a prone position and the course of the sciatic nerve was marked on the right hip (E). Kirschner wire was used to locate the AFIT (F). (AFIT, avulsion fracture of the ischial tuberosity.)

Creation of Surgical Portals and Arthroscopic Access

Two surgical portals are created, one 2 cm inferior and the other 2 cm superior to the Kirschner wire, to enable endoscopic procedures such as the placement of suture anchors and the tying of suture knots. The arthroscope is introduced into the posterior gluteal compartment through the inferior portal. This approach allows for direct visualization of the ischial tuberosity along the path of the Kirschner wire. During the arthroscopic examination, the intact proximal footprint of the hamstring tendon is clearly observed, providing essential information for the subsequent steps of the surgical procedure (Fig 2). The sciatic nerve is preoperatively mapped on the skin to guide safe portal placement. Intraoperatively, only minimal perilesional tissue was released to avoid excessive dissection and minimize the risk of sciatic-nerve injury.

Fig 2.

Surgical process of arthroscopic treatment of AFIT in the right hip. A Kirschner wire was used to locate the right ischial tubercle (A, D). Two additional Kirschner wires were used for the fixation of displaced fragment (B, E). Two suture anchors were inserted to fix the fracture pieces stably by using the double-pulley suture-bridge technique (D, F). (AFIT, avulsion fracture of the ischial tuberosity.)

Intraoperative Identification and Localization of Avulsion Fracture

During surgery, the avulsion fracture and its associated callus are identified approximately. Intraoperative C-arm fluoroscopy (OEC 9900 Elite; GE Healthcare, Chicago, IL) is used to verify the location of avulsion fracture. Subsequently, two 2.0-mm Kirschner wires are placed under the C-arm fluoroscopy 1 cm superior and inferior to the fracture, respectively. An additional third assisted portal is created above the avulsion fracture to facilitate the placement of the suture anchor (Fig 3).

Fig 3.

Arthroscopic view from the superior portal of the right hip showing the “double-pulley” suture anchor fixation. Two suture anchors were inserted on the bony fragment to replace the Kirschner wires. The suture strands in same color of these 2 anchors were tied with a static surgical knot in “double-pulley” knot-tying fashion. The other 2 suture strands with the same color were tied with similar maneuver repeatedly.

Placement of Suture Anchors and Internal Fixation

Two suture anchors (4.5-mm HEALICOIL PK; Smith & Nephew, Andover, MA) are then inserted at the sites of the previously placed Kirschner wires on the bony fragment. The same color of suture strands from these anchors are then meticulously tied using a static surgical knot in a "double-pulley" fashion. A similar technique is applied to the remaining 2 suture strands of the same color (Fig 3).

Confirmation of Fracture Reduction and Stability

The stability of the bony fragment is confirmed under arthroscopy, ensuring it is securely fixed. The successful reduction of the fracture was further verified with C-arm fluoroscopy, providing visual confirmation of the precision and effectiveness of the surgical procedure (Video 1).⁶

Postoperation Rehabilitation

The day after the surgery, the patient can begin using crutches for non−weight-bearing walking. To limit the range of motion in both the knee and hip, a specially prescribed brace is used, restricting hip flexion to 45° and extension to 10° for the first 4 weeks. Passive assistive hamstring stretches are performed once or twice daily. From the fourth week onwards, active exercises are allowed, and the patient gradually progresses to one-third weight-bearing. By the eighth week, the patient is cleared for full weight-bearing. Follow-up assessments for our patient were conducted at 1, 3, 6, and 12 months postsurgery. Radiographs and computed tomography scanning indicated evidence of healing at 6 months postoperatively and complete bony union by the 12-month postoperative period. Magnetic resonance imaging scans at the 12-month follow-up confirmed bony healing and the absence of residual edema around the AFIT, indicating a successful recovery process (Fig 4).

Fig 4.

12-month follow-up results. Radiograph (A) and computed tomography (B) indicated an evident healing and bony union of the right ischial tubercle. Magnetic resonance imaging (C) and 3-dimensional reconstruction (D) demonstrated bony healing without focus edema.

Discussion

In this case, the patient experienced 6 months of unsuccessful conservative management before seeking help from us. Rest and physiotherapy failed to resolve his buttock pain and hip dysfunction. In addition, imaging continued to show a 5-mm avulsed fragment displaced at 6 months, which is an indication of impending nonunion and ongoing symptoms if left untreated. Given this progressive functional decline and his desire to resume high-level sports, he and his parents opted for arthroscopic reduction and internal fixation, which offers reliable fragment healing and a quicker, more predictable return to activity than further conservative care.

Concerns surrounding the limitations of conservative treatment for AFIT, particularly in terms of complications and delayed recovery, have spurred innovations in surgical techniques. The introduction of the "double-pulley" suture anchor technique in this context represents a significant advancement. This method offers a potential solution to the challenges traditionally associated with AFIT surgeries, aiming to improve outcomes and reduce the risk of complications, particularly for those cases in whom conservative methods may not be effective.

Conservative treatment is generally recommended for patients with a displacement of less than 15 to 20 mm. However, it is imperative to consider the greater rate of complications associated with conservative treatment, especially for athletes. The rate of complications in athletes can be as high as 33%, in contrast to a lower rate of 16% in those who undergo surgical intervention. These complications include nonunion, fibrosis, chronic pain, leg muscle weakness, and heterotrophic bone formation.^5,7 Published studies have shown that patients undergoing conservative treatment might experience heterotrophic bone formations during the healing process, especially if the acute phase of the injury is not promptly addressed.^8,9 In light of this, surgery is often seen as a preferable option because of its greater success rate in returning athletes to sports and its potential to reduce the risk of complications.

Surgical intervention for AFIT with significant displacement has consistently demonstrated long-term satisfactory outcomes.¹⁰ There are several internal fixation options available for AFIT, each tailored to the specifics of the case. For example, metal screws, plates, absorbable screws, suture anchors, and Kirschner wires tension band can be used on the basis of the specific case requirements. For larger fractures, open reduction with plate and screw fixation may be considered. In more complex cases, particularly those involving advanced nonunion, the Kocher-Langenbeck approach is often the preferred surgical method. This approach facilitates plate fixation to the outer edge of the ischial tuberosity, preventing direct contact between the internal fixation and seating surfaces during sitting.¹¹

The advancements in arthroscopic techniques and instrumentation provide the possibility of new arthroscopic approach to AFIT treatment. The combination of preoperative 3-dimensional CT imaging, intraoperative arthroscopic views, and C-arm fluoroscopy provides exceptional accuracy in positioning AFIT. Under arthroscopy, the "double-pulley" suture anchor technique stands out as a reliable and efficient means of fixation for AFIT. It offers robust mechanical strength, which is vital for facilitating early and effective rehabilitation. This aspect of the technique is particularly significant, as it enables patients to commence their recovery process sooner. The absence of secondary internal fixation removal for the suture anchor eliminates potential soft tissue irritation associated with metal hardware.

Nevertheless, this technique also carries some risks and limitations that warrant careful consideration. For example, nonanatomical placement of suture anchors may compromise fixation strength and fracture healing, while deviations in intraoperative imaging guidance can lead to imprecise reduction, elevating risks of postoperative nonunion or displacement. Inadequate protection of the sciatic nerve during portal establishment or tissue release may potentially cause iatrogenic nerve injury. The efficacy of this technique for fractures with displacement >2 cm remains to be validated, necessitating large-scale studies to define its applicability spectrum. Long-term outcomes, including potential complications such as heterotopic ossification or fixation failure, require extended follow-up data, which are presently unavailable. And the steep learning curve associated with arthroscopic proficiency and real-time image-guided navigation may restrict widespread adoption.¹² Advantages, pitfalls, and limitations of this arthroscopic technique are summarized in Tables 2 and 3. The surgical procedure is showed in Video 1.

Table 2.

Pearls and Pitfalls

Pearls	Pitfalls
Arthroscopic surgery demonstrates efficacy in precisely reducing and securing AFIT.	Nonanatomical placement of suture anchors may lead to insufficient fixation strength or biomechanical abnormalities, compromising fracture healing.
The combination of preoperative 3-dimensional computed tomography imaging, intraoperative arthroscopic visualization, and C-arm fluoroscopy provides exceptional accuracy in AFIT localization.	Intraoperative imaging guidance deviations can result in imprecise fracture reduction, increasing the risk of postoperative nonunion or displacement.
The "double-pulley" suture anchor technique delivers robust mechanical strength, enabling reliable and efficient AFIT fixation, which is critical for promoting early and effective rehabilitation.	Neglecting concomitant soft tissue injuries (eg, inadequate protection of the sciatic nerve pathway) may cause iatrogenic nerve damage.
	Anchor implantation in skeletally immature patients (with open growth plates) risks disrupting physeal development.

AFIT, avulsion fracture of the ischial tuberosity.

Table 3.

Advantages and Disadvantages

Advantages	Disadvantages
This surgical technique is minimally invasive with soft-tissue preservation compared with open surgery.	The general applicability of this technique in cases with significant displacement (>2 cm) remains unclear, and its efficacy requires validation through large-scale clinical studies.
This technique provides a potential method for those whose performance might suffer under conservative care yet do not meet the classic >2 cm threshold for open surgery.	Long-term outcomes and potential complications (eg, heterotopic bone formation, fixation failure) necessitate further long-term follow-up data.
The secure internal fixation permits early controlled motion, progressive weight bearing, and a planned quicker return to full activity, potentially shortening time away from sport.	Surgical success heavily depends on the surgeon’s proficiency in arthroscopic techniques and image-guided navigation, resulting in a steep learning curve.
	Limited applicability for fragments <5 mm or osteoporotic bone

Funding

This work was partially supported by grants from the Natural Science Foundation of Hunan Province and Health Research Project of Hunan Provincial Health Commission (2023JJ40823, W20243122 to Y.H.).

Disclosures

All authors (T.L., J.L., A.W., W.Z.) declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Supplementary Data

Video 1

Arthroscopic fixation of minimally displaced avulsion fracture of the right ischial tuberosity using the “double-pulley” suture anchor technique. Under general anesthesia, the patient is positioned prone, and the course of the sciatic nerve is marked. Then a 2.0-mm guide Kirschner wire is percutaneously placed into the ischial tuberosity under fluoroscopy to serve as a radiographic beacon and axis for instrument orientation. Two standard posterior-gluteal arthroscopy portals are established 2 cm superior and inferior to this wire. Then, the scope is introduced to visualize the posterior gluteal compartment. Arthroscopic examination confirms that the hamstring footprint is intact. The avulsed fragment is identified, and its location is confirmed with intraoperative C-arm. After confirming fragment mobility, the fracture bed is lightly decorticated with a burr to promote healing, and 2 additional 2.0-mm guidewires are placed, one 1 cm above and one 1 cm below the fracture line, defining the future anchor sites. Over these guides, two 4.5-mm HEALICOIL PK suture anchors (Smith & Nephew, Andover, MA) preloaded with high-strength sutures are delivered through a short accessory portal that sits directly over the fragment and replaces the original localizing wire. Once the anchors are seated, arthroscopic suture-passing devices shuttle the same-colored limbs of each anchor through drill holes across the fragment, and the strands are tied extracorporeally with sliding Weston knots, creating a double-pulley construct that cinches the bone uniformly against its bed and resists both rotation and shear. Anatomic reduction and stable fixation are finally verified arthroscopically and fluoroscopically before portal closure.