Avulsion fracture of the ischial tuberosity treated with the suture bridge technique: a case report
In cases of avulsion fracture of the ischial tuberosity in which the bone fragments are substantially displaced, nonunion may cause pain in the ischial area. Various surgical procedures have been reported, but achieving sufficient fixation strength is difficult.
We treated a 12-year-old male track-and-field athlete with avulsion fracture of the ischial tuberosity by suture anchor fixation using the suture bridge technique. The boy felt pain in the left gluteal area while running. Radiography showed a left avulsion fracture of the ischial tuberosity with approximately 20-mm displacement. Union was not achieved by conservative non-weight-bearing therapy, and muscle weakness persisted; therefore, surgery was performed. A subgluteal approach was taken via a longitudinal incision in the buttocks, and the avulsed fragment was fixed with five biodegradable suture anchors using the suture bridge technique.
Although the majority of avulsion fractures of the ischial tuberosity can be treated conservatively, patients with excessive displacement require surgical treatment. The suture bridge technique provided secure fixation and enabled an early return to sports activities.
KeywordsInjury Ischial avulsion Surgical repair Suture bridge
Manual muscle testing
Magnetic resonance imaging
Range of motion
Straight leg raising
Pelvic apophyseal avulsion fracture is a category that includes a few types of avulsion fractures. Avulsion fractures of the anterior inferior iliac spine, anterior superior iliac spine, and iliac crest are comparatively common, but avulsion fractures of the ischial tuberosity are rarely described in the literature . However, this fracture is frequently observed in athletes during growth spurts. The underlying mechanism involves damage to the vulnerable epiphyseal plate before epiphyseal arrest, caused by sudden and forceful eccentric contraction of the hamstrings and is attributed to sprinting or jumping. Bone union must be achieved, and range of motion (ROM) and muscle strength should be restored before full return to sports activities. However, patients with substantial displacement, sciatic nerve complications, or nonunion after conservative treatment require surgical treatment with adequate fixation. We report a case in which suture anchor fixation using the suture bridge technique was applied for the treatment of avulsion fracture of the ischial tuberosity.
Discussion and conclusions
Since the first description by Berry in 1912 , avulsion fracture of the ischial tuberosity before epiphyseal arrest has been reported [1, 4, 5]. The mechanically vulnerable unfused apophysis can be injured as a result of traction force imposed by intense muscle contractions of the hamstrings during sports activities. This injury occurs most commonly during hurdles and high jump, possibly because of the eccentric contraction of the hamstrings when the leg is forced into hyperflexion of the hip with the knee fully extended [6, 7, 8].
Conservative treatment is the standard primary treatment modality for avulsion fracture of the ischial tuberosity [9, 10], but nonunion, fibrosis, overgrowth, buttock pain, and muscle weakness tend to occur [5, 11, 12, 13]. Avoca and Okay therefore reported that although patients with < 20 mm displacement might be successfully treated with conservative methods , surgical treatment is recommended if the displacement is ≥20 mm [15, 16]. Surgical treatment is also recommended for patients with sciatic nerve complications .
Wood et al. reported that a delay in surgical repair renders the repair more technically challenging, may increase the likelihood of sciatic nerve involvement, increases the need for postoperative bracing, and reduces postoperative outcomes in terms of hamstring strength and endurance . In this case, we used a longitudinal incision. One disadvantage of the longitudinal incision is that this incision is cosmetically inferior to a transverse incision along the gluteal crease [4, 18]. However, the longitudinal incision enabled extension of the skin incision on demand, providing a good view for mobilization of the hamstrings. In addition, we did not expose the sciatic nerve in this case, avoiding the potential risk of sciatic nerve disturbance .
The surgical techniques reported previously include the use of a reconstruction plate, lag screws, and suture anchors [4, 19, 20, 21]. Kaneyama et al. reported the use of fixation with a cancellous screw and washer assembly . Watts et al. attempted a minimally invasive surgical procedure involving percutaneous fixation using two cannulated cancellous screws but failed to reduce the fracture adequately . Surgical techniques using suture anchors have recently been reported [21, 22, 23]. Biedert et al. reported the use of single-row suture anchor fixation in patients with displacement ≥20 mm, with a good final outcome . However, they also reported that one patient needed operative revision one day after primary repair because of suture loosening. We consider that irrespective of whether screw fixation or suture anchor fixation is used, the shell-shaped avulsed fragment is difficult to fix using only one or two devices. An in vitro biomechanical analysis by Hamming et al. found that fixation with two anchors was mechanically insufficient and recommended fixing the avulsed fragment with five anchors . This report appears to represent the first description of using the suture bridge technique with five suture anchors to treat avulsion fracture of the ischial tuberosity. The suture bridge technique is a rotator cuff repair technique that was first described by Park et al. in 2007 , with improved pressurized contact between the tendon and tuberosity compared with the double-row technique. In the present case, fixation using the suture bridge technique enabled stronger pressure between bone fragments over a wider area than that provided by simple suture anchor fixation.
The postoperative orthosis used in this case was a Snyder sling, a sling originally used to treat Perthes disease . The Snyder sling is a variable angle brace, and we extended the knee in accordance with the state of hamstring stretching. We were thus able to gradually increase stretching stress on the hamstrings as bone union was achieved, eventually enabling a smooth return to sports activities. Skaara et al. reported that minor pain and limitations to activities of daily living were observed after surgical repair using the suture anchor technique, that isokinetic hamstring strength in the operated leg was significantly lower than that in the nonoperated leg and that a majority of patients did not trust the operated leg completely during physical activity . In the present case in which the patient was treated with the suture bridge technique, the LEFS at the final follow-up was 100%. Although reports of surgical techniques and postoperative physical therapy for avulsion fracture of the ischial tuberosity are rare, good results may be achieved by combining good surgical therapy with aggressive physical therapy interventions to reduce stretching stress on the ischial tuberosity.
In conclusion, although the majority of avulsion fractures of the ischial tuberosity can be treated conservatively, patients with excessive displacement require surgical treatment. The suture bridge technique is a useful technique that provides sufficient strength for avulsion fracture of the ischial tuberosity.
We would like to thank American Journal Experts for English language editing.
This research was supported by JSPS KAKENHI, Grant Number JP17K16691 (publication cost). The funding body had no role in the design of the study and collection, analysis, and interpretation of data and in writing the manuscript.
Availability of data and materials
All data concerning the case are presented in the manuscript.
All the authors (TT1, HE, TT2, KY, TF and TO) took part in the conception and design of the study. TT1 and HE participated in the surgical and medical treatment. TT1, HE and TT2 contributed to manuscript drafting and interpretation of data. KY, TF and TO revised the manuscript critically for important intellectual content. All authors (TT1, HE, TT2, KY, TF and TO) read and approved the final version of the manuscript.
Ethics approval and consent to participate
All procedures were part of the standard medical care, and the need for ethics approval and consent to participate was waived.
Consent for publication
Written informed consent was obtained from the patient and parent for the publication of this report and any accompanying images.
The authors declare that they have no competing interests.
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