Orthopedics

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Case Reports 

Superior Gluteal Artery Injury During Iliosacral Screw Placement due to Aberrant Anatomy

Meir Marmor, MD; Terry Lynch, MD; Amir Matityahu, MD

Abstract

Percutaneous iliosacral screws are considered the standard of care for disruptions of the sacroiliac joint. This article describes a case of iatrogenic injury to the superior gluteal artery during iliosacral screw insertion and analyzes the possible reasons for this complication.

A 32-year-old man diagnosed with an unstable pelvic ring injury underwent percutaneous fixation of the right sacroiliac joint. A 2-cm skin incision was made, and a straight cannulated awl was placed with the tip directly lateral to the S1 body. A guide wire was inserted and a partially threaded 6.5-mm cannulated screw with a washer was then placed over the guide wire and was found to be in excellent position. At this time, increased bleeding from the incision was observed. The incision was enlarged and dissection was carried down through the muscle. The bleeding vessel could not be visualized. Therefore, the wound was packed with sponges, and coil embolization of the right superficial gluteal artery was successfully performed.

Analysis of the angiography reveled that our patient’s superficial branch of the superior gluteal artery measured more than twice the average length reported in a previous anatomic study. We believe this is the first case of superior gluteal artery bleeding due to aberrant superior gluteal artery anatomy. When planning iliosacral screw insertion, the possibility of anatomical variance of the superior gluteal artery should be acknowledged and sought after in preoperative angiography, when available.

Percutaneous iliosacral screws are considered the standard of care for posterior pelvic ring injuries or disruptions of the sacroiliac joint.1 The spectrum of possible iliosacral screw trajectories render the iliac vessels located anterior to the sacral alar region as well as the fifth lumbar and first sacral nerve roots susceptible to injury.2,3 Avoiding these complications requires a thorough understanding of pelvic anatomy and the acquisition of high-quality intraoperative imaging.3

This article presents a case of iatrogenic injury to the superior gluteal artery and analyzes the possible reasons for this complication. A literature review was performed in PubMed and Embase using the following search terms and medical subheadings (MeSH) terms: sacral screws, iliac screws, sacroiliac screws, iliosacral screw/s, percutaneous pelvic screw/s, pelvic/s fracture/s, complications, vascular injury, superior gluteal artery.

A 32-year-old man presented after a motor vehicle accident. Initial assessment showed pain on pelvic stress and motion of the pelvis. A pelvic binder was applied. A pelvic radiograph showed a widened pubic symphysis. Computed tomography (CT) of the pelvis showed a coccyx fracture and hematoma, pubic symphysis widening, and slight widening of the right sacroiliac joint (Figure 1).

Figure 1: CT scan of the pelvis showing slight widening of the right sacroiliac joint.

The following day, the patient underwent examination under anesthesia to assess pelvic stability. He was found to have pubic symphysis widening of 4.5 cm with external rotation of the right hemipelvis relative to the left hemipelvis. Therefore, open reduction and internal fixation of his symphysis dislocation and percutaneous fixation of his right sacroiliac dislocation was performed.

The surgical procedure began with an open reduction and internal fixation of the pubic symphysis. Next, percutaneous fixation of the right sacroiliac joint was performed. A lateral fluoroscopic image of the sacrum with the acetabuli overlapping and the anterior sacral alar line was performed. A 2-cm incision was made directly lateral to the S1 body. A straight cannulated awl was placed percutaneously with the tip directly lateral to the S1 body and inferior and anterior to the sacral alar line.

A guide wire was then introduced with anteroposterior, inlet, and outlet pelvic fluoroscopic views showing the guide wire to be in excellent position. The straight cannulated awl was then removed. At…

Abstract

Percutaneous iliosacral screws are considered the standard of care for disruptions of the sacroiliac joint. This article describes a case of iatrogenic injury to the superior gluteal artery during iliosacral screw insertion and analyzes the possible reasons for this complication.

A 32-year-old man diagnosed with an unstable pelvic ring injury underwent percutaneous fixation of the right sacroiliac joint. A 2-cm skin incision was made, and a straight cannulated awl was placed with the tip directly lateral to the S1 body. A guide wire was inserted and a partially threaded 6.5-mm cannulated screw with a washer was then placed over the guide wire and was found to be in excellent position. At this time, increased bleeding from the incision was observed. The incision was enlarged and dissection was carried down through the muscle. The bleeding vessel could not be visualized. Therefore, the wound was packed with sponges, and coil embolization of the right superficial gluteal artery was successfully performed.

Analysis of the angiography reveled that our patient’s superficial branch of the superior gluteal artery measured more than twice the average length reported in a previous anatomic study. We believe this is the first case of superior gluteal artery bleeding due to aberrant superior gluteal artery anatomy. When planning iliosacral screw insertion, the possibility of anatomical variance of the superior gluteal artery should be acknowledged and sought after in preoperative angiography, when available.

Percutaneous iliosacral screws are considered the standard of care for posterior pelvic ring injuries or disruptions of the sacroiliac joint.1 The spectrum of possible iliosacral screw trajectories render the iliac vessels located anterior to the sacral alar region as well as the fifth lumbar and first sacral nerve roots susceptible to injury.2,3 Avoiding these complications requires a thorough understanding of pelvic anatomy and the acquisition of high-quality intraoperative imaging.3

This article presents a case of iatrogenic injury to the superior gluteal artery and analyzes the possible reasons for this complication. A literature review was performed in PubMed and Embase using the following search terms and medical subheadings (MeSH) terms: sacral screws, iliac screws, sacroiliac screws, iliosacral screw/s, percutaneous pelvic screw/s, pelvic/s fracture/s, complications, vascular injury, superior gluteal artery.

Case Report

A 32-year-old man presented after a motor vehicle accident. Initial assessment showed pain on pelvic stress and motion of the pelvis. A pelvic binder was applied. A pelvic radiograph showed a widened pubic symphysis. Computed tomography (CT) of the pelvis showed a coccyx fracture and hematoma, pubic symphysis widening, and slight widening of the right sacroiliac joint (Figure 1).

Figure 1: Slight widening of the right sacroiliac joint

Figure 1: CT scan of the pelvis showing slight widening of the right sacroiliac joint.

The following day, the patient underwent examination under anesthesia to assess pelvic stability. He was found to have pubic symphysis widening of 4.5 cm with external rotation of the right hemipelvis relative to the left hemipelvis. Therefore, open reduction and internal fixation of his symphysis dislocation and percutaneous fixation of his right sacroiliac dislocation was performed.

The surgical procedure began with an open reduction and internal fixation of the pubic symphysis. Next, percutaneous fixation of the right sacroiliac joint was performed. A lateral fluoroscopic image of the sacrum with the acetabuli overlapping and the anterior sacral alar line was performed. A 2-cm incision was made directly lateral to the S1 body. A straight cannulated awl was placed percutaneously with the tip directly lateral to the S1 body and inferior and anterior to the sacral alar line.

A guide wire was then introduced with anteroposterior, inlet, and outlet pelvic fluoroscopic views showing the guide wire to be in excellent position. The straight cannulated awl was then removed. At this moment, a slight amount of blood began to expel from the wound. A partially threaded 6.5-mm cannulated screw with a washer was then placed over the guide wire and was found to be in excellent position. Bleeding from the incision continued and began to increase. The incision was then enlarged, and dissection was carried down through the muscle. The bleeding vessel could not be adequately visualized to be clamped, and it was felt that further extension of the posterior incision would not aid in achieving hemostasis. The wound was packed with sponges and closed with staples, and the patient was transferred to the angiography department where coil embolization of the right superficial gluteal artery was performed. It was noted that the patient had a longer than typical superior gluteal artery with visible extravasation (Figure 2). The patient received 2 units of packed red blood cells and maintained a normal blood pressure and heart rate while in the angiography suite. After embolization was performed, the wound was opened, unpacked, irrigated, and closed in layers. The patient has done well postoperatively without pelvic pain or neurological deficits.

Figure 2: Extravasation near the insertion site of the sacroiliac screw

Figure 2: Angiography of the right superficial gluteal artery showing visible extravasation near the insertion site of the sacroiliac screw.

Discussion

During 2007, the senior author (A.M.) performed 62 posterior percutaneous pelvic stabilization procedures for sacral fractures or sacroiliac joint dislocations. During that time, 1 vascular complication occurred as described above. We believe that the reason for this complication was a superior gluteal artery anatomic abnormality that led to injury to the superior gluteal artery despite adequate surgical technique.

The superior gluteal artery is the largest posterior branch of the internal iliac (hypogastric) artery.4 It runs posteriorly between the lumbosacral trunk and the first sacral nerve root, passing out of the pelvis through the upper part of the greater sciatic foramen, above the upper border of the piriformis muscle. Within the pelvis it supplies the iliacus, piriformis, and obturator internus. Just previous to exiting the pelvis, the artery gives off a nutrient branch that enters the ilium. After exiting the pelvis, the artery immediately divides into a superficial and a deep branch (Figure 3). The superficial branch supplies upper one-third of the gluteus maximus muscle and divides into numerous branches, some of which anastomose with the inferior gluteal, while others perforate its tendinous origin, and supply the integument covering the posterior surface of the sacrum. The deep branch supplies the gluteus minimus and medius, traveling in the facial plane between these muscles. The deep branch almost immediately divides into a deep superior division and a deep inferior division.5 The superior division, continuing the original course of the vessel, passes along the upper border of the gluteus minimus to the anterior superior spine of the ilium, anastomosing with the deep iliac circumflex artery and the ascending branch of the lateral femoral circumflex artery. The inferior division crosses the gluteus minimus obliquely to the greater trochanter, distributing branches to the glutei and anastomoses with the lateral femoral circumflex artery.

Figure 3: Extravasation near the insertion site of the sacroiliac screw
Figure 4: Extravasation near the insertion site of the sacroiliac screw

Figure 3: Superior gluteal artery anatomy (plotted in red) according to an anatomic study.8 Iliosacral screw trajectory area (blue circle) according to a cadaveric study.13 Abbreviations: SGAsb, superficial branch of superior gluteal artery; SGAsdp, superior division of the deep branch of the superior gluteal artery; SGAidp, inferior division of the deep branch of the superior gluteal artery. Figure 4: Superior gluteal artery anatomy in our case according to image analysis of angiographic study (Figure 2). Iliosacral screw trajectory area (blue circle) as reported by a cadaveric study.13 The circle indicates the previously published area of screw insertion that resulted in injury to the superior gluteal neurovascular complex.13 Abbreviations: SGAsb, superficial branch of superior gluteal artery; SGAsdp, superior division of the deep branch of the superior gluteal artery; SGAidp, inferior division of the deep branch of the superior gluteal artery.

In an anatomic study based on 20 cadaveric dissections, the superior gluteal artery was found to exit from the greater sciatic notch at a distance of 60-mm from the posterior superior iliac spine and 42 mm from the posterior inferior iliac spine.5 Compared to a transverse reference line between the anterior inferior iliac spine and posterior inferior iliac spine (which roughly tangents the superior border of the sciatic notch), the superior division of the deep branch continuously reached a point 5 to 30 mm above the reference line. However this was at a vertical line crossing the transverse line 80 mm from the posterior inferior iliac spine (not in iliosacral screw trajectory). The superficial branch of the superior gluteal artery averaged 21 mm in length (range, 10-35 mm), extending vertically up to 20 mm superior to the reference line at an average angle of 65° to the deep superior branch, and 103° from the deep inferior branch (Figure 3).5

Because the 6.5-mm iliosacral screw was put in place before performing the angiography in our case, we were able to use the screw dimensions as calibration for calculating the anatomic characteristics of our patient’s superior gluteal artery and compare them to the above-mentioned study (Figure 2).

In accordance with the anatomical study described above,5 the superficial and deep branches divided immediately (5.2 mm) after exiting the greater sciatic notch, the diameter of the superficial branch was 3.8 mm at branch point and up to bleeding point (compared to an average of 4.3±0.8 mm [range, 3-6 mm] at branch point to 3.2±0.7 mm at insertion in the anatomic study). However, unlike the anatomic study, our patient’s superficial branch of the superior gluteal artery measured 54.4 mm up to the bleeding point, where as the average length in the anatomic study was 21 mm (range, 10-35 mm).

The insertion point site for iliosacral screw lies along the posterior ilium between the greater sciatic notch and the iliac crest.6,7 To the best of our knowledge, damage to the superior gluteal neurovascular bundle during clinical iliosacral screw insertion has been reported previously only once.8 The authors reported brisk arterial bleeding coming out of the percutaneous wound after insertion of a drill guide in a 69-year-old patient. They attributed the injury to calcification of the vessel seen on CT. They hypothesized that the arterial injury may have been due to either a direct injury from the drill guide or a traction injury. Our case demonstrates that injury can occur in young patients with aberrant arterial superior gluteal artery anatomy and without calcified arteries.

Stephen9 reported a pseudoaneurysm of the superior gluteal artery diagnosed 15 days after percutaneous iliosacral screw insertion. He presumed that the etiology of the pseudoaneurysm was multifactorial and may have occurred as a result of the initial fracture displacement and/or direct trauma from the screw insertion. As in our case and the previously mentioned case report,8 successful treatment of the pseudoaneurysm was achieved by embolization.

In a previous cadaveric study of injuries to the superior gluteal nerve and vessels after iliosacral screw insertions, the authors inserted 58 iliosacral screws and found that 18% of them injured the superior division of the deep branch of the superior gluteal artery neurovascular bundle.10 However, the authors did not differentiate between nerve and vessel injury, and their description of the screw trajectory fit the position of the superficial branch of the superior gluteal artery as was described in the previous anatomical study.5

When we plotted the typical superior gluteal artery anatomy and the screw insertion area reported by these 2 studies on a computerized 3D model of the pelvis, it was apparent that the usual iliosacral screw trajectory does not coincide with the superior gluteal artery (Figure 3). However, when we plotted the aberrant superior gluteal artery anatomy observed in this case on the same 3D pelvis model, the iliosacral screw trajectory area seemed to coincide with the observed location of the superior gluteal artery, possibly explaining the vascular incident (Figure 4).

Open screw insertion in our patient may have avoided this injury, but superior gluteal artery injuries have been associated with other open orthopedic procedures, such as posterior iliac crest bone harvesting and revision acetabular surgery. Treatment of these superior gluteal artery injuries has differed from extensile exposure and ligation of the artery to embolization.11,12 In our patient, tamponade was effective in initially controlling arterial hemorrhage, and urgent angiographic embolization was successful. The immediate availability and technical expertise of the interventional radiologist enabled this injury to be managed rapidly, without any adverse clinical effects.

References

  1. Shuler TE, Boone DC, Gruen GS, Peitzman AB. Percutaneous iliosacral screw fixation: early treatment for unstable posterior pelvic ring disruptions. J Trauma. 1995; 38(3):453-458.
  2. Templeman D, Schmidt A, Freese J, Weisman I. Proximity of iliosacral screws to neurovascular structures after internal fixation. Clin Orthop Relat Res. 1996; (329):194-198.
  3. Routt ML Jr, Kregor PJ, Simonian PT, Mayo KA. Early results of percutaneous iliosacral screws placed with the patient in the supine position. J Orthop Trauma. 1995; 9(3):207-214.
  4. Gray, H. Anatomy of the Human Body. 20th ed. Philadelphia, PA: Lea & Febiger; 1918; Bartleby.com, 2000. Available at: http://www.bartleby.com/107/. Accessed March 26, 2009.
  5. Ebraheim NA, Olexa TA, Xu R, Georgiadis G, Yeasting RA. The quantitative anatomy of the superior gluteal artery and its location. Am J Orthop. 1998; 27(6):427-431.
  6. Carlson DA, Scheid DK, Maar DC, Baele JR, Kaehr DM. Safe placement of S1 and S2 iliosacral screws: the “vestibule” concept. J Orthop Trauma. 2000; 14(4):264-269.
  7. Day CS, Prayson MJ, Shuler TE, Towers J, Gruen GS. Transsacral versus modified pelvic landmarks for percutaneous iliosacral screw placement–a computed tomographic analysis and cadaveric study. Am J Orthop. 2000; 29(9 suppl):16-21.
  8. Altman DT, Jones CB, Routt ML Jr. Superior gluteal artery injury during iliosacral screw placement. J Orthop Trauma. 1999; 13(3):220-227.
  9. Stephen DJG. Pseudoaneurysm of the superior gluteal arterial system: an unusual cause of pain after pelvic fracture. J Trauma. 1997; 43(1):146-149.
  10. Collinge C, Coons D, Aschenbrenner J. Risks to the superior gluteal neurovascular bundle during percutaneous iliosacral screw insertion: an anatomical cadaver study. J Orthop Trauma. 2005; 19(2):96-101.
  11. Kahn B. Superior gluteal artery laceration, a complication of iliac bone graft surgery. Clin Orthop Relat Res. 1979; (140):204-207.
  12. Oppenheim WL, Harley JD, Lippert FG. Arteriographic management of post-operative bleeding following major hip surgery. J Bone Joint Surg Am. 1975; 57(1):127-128.
  13. Collinge C, Coons D, Aschenbrenner J. Risks to the superior gluteal neurovascular bundle during percutaneous iliosacral screw insertion: an anatomical cadaver study. J Orthop Trauma. 2005; 19(2):96-101.

Authors

Drs Marmor, Lynch, and Matityahu are from the Orthopaedic Trauma Institute UCSF, San Francisco General Hospital, San Francisco, California.

Drs Marmor, Lynch, and Matityahu have no relevant financial relationships to disclose.

Correspondence should be addressed to: Meir Marmor, MD, Orthopaedic Trauma Institute UCSF, San Francisco General Hospital, 2550 23rd Street, Bldg 9, 2nd Fl, San Francisco, CA 94110 (marmorm@orthosurg.ucsf.edu).

doi: 10.3928/01477447-20100104-26

10.3928/01477447-20100104-26

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