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Stabilization of a Type B1.1 Injury in a Morbidly Obese Patient Using an Internal Fixator in a Minimally Invasive Technique

A Case Report

Fritz, Tobias MD1; Braun, Benedikt J. MD1; Veith, Nils T. MD1; Hopp, Sascha J. MD1,2; Mettelsiefen, Laura1; Strobel, Friedemann1; Pohlemann, Tim MD1; Pizanis, Antonius MD1

doi: 10.2106/JBJS.CC.18.00075
Case Reports
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Disclosures

Case: In this case report, we present a novel stabilization technique of the pubic symphysis using an internal spinal fixator in a 78-year-old morbidly obese woman having a pelvic disruption type B1.1 (AO classification). We treated the disruption using an internal fixator to reduce the extent of the incision and soft-tissue damage.

Conclusions: The use of an internal fixator, known from percutaneous spinal fixation, for the stabilization of the pubic symphysis in cases of disruption (“open book” injuries) may be an alternative to the standard plate fixation as a novel minimally invasive stabilization technique.

1Department of Trauma, Hand and Reconstrutive Surgery, Saarland University Hospital, Homburg, Germany

2Lutrina Clinic, Kaiserslautern, Germany

E-mail address for T. Fritz: tobias.fritz@uks.eu

Investigation performed at Saarland University Medical Center, Homburg, Germany

Disclosure: The Disclosure of Potential Conflicts of Interest forms are provided with the online version of the article (http://links.lww.com/JBJSCC/A842).

Pelvic fractures in adults are common injuries and account for up to 3.7 % of all fractures. The standard treatment for most disruptions of the pubic symphysis (Type B1.1 and B1.2 AO-CCF Classification) is open reduction and internal fixation with a reconstruction plate used in dynamic compression with or without interlocking screws.

These implants seem to enhance the level of the outcome of such injuries but are also associated with significant complications, for example, hardware failure, screw loosening, and infection, as well as chronic instability1,2.

The patient was informed that data concerning the case would be submitted for publication, and she provided consent.

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Case Report

A 78-year-old morbidly obese woman (body mass index 39.1 kg/m2) was presented to our hospital after falling to the floor in her living room. On clinical examination, an unstable pelvis was detected. An immediate pelvic stabilization was performed using a pelvic binder in the emergency department (T-POD, Winther Medical). Radiography (Fig. 1-A) and computed tomography (CT) scans were performed after admission. The injury was classified as type B1.1 according to the AO/OTA classification. Because of fungal skin irritation in the presymphyseal area, the immediate temporary stabilization of the unstable pelvis using the supra-acetabular external fixator was applied3,4. Postoperative conventional radiographs showed an adequate reduction of the pubic symphysis (Fig. 1-B).

Fig. 1

Fig. 1

Because of the extent of the injury and the trauma mechanism, we decided that permanent internal fixation would be necessary to achieve a stable result and thereby prevent the infection risk resulting from leaving an external fixator in situ for 2 to 3 months. The patient's morbid obesity required extensive preoperative planning. Using conventional treatment methods5,6, we estimated that the conventional open Pfannenstiel approach would be too extensive, so we decided to use an internal fixator commonly used for spinal fractures in a minimally invasive fashion7 and discussed the procedure with the patient, obtaining formal consent. Preliminary ex vivo biomechanical tests of minimally invasive fixation options of the pubic symphysis had already suggested equal implant stability to conventional plating techniques1,8-12. The definitive stabilization of the pubic symphysis was performed 7 days after the injury.

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Surgical Technique

The patient was positioned in a supine position on the operating table. Even in an optimized position, the pannus had to be draped cranially by adhesive tapes to allow access to the operative field (Fig. 2).

Fig. 2

Fig. 2

Preoperative fluoroscopy allowed skin marking of the minimally invasive surgical approach. A small Pfannenstiel skin incision of 5 cm was performed, and the fascia of the rectus muscle and the muscle itself were split craniocaudal, without detachment from the bone. In the next step, the fluoroscopy was set for inlet/outlet pelvic views, and a Kirschner wire was introduced through a Jamshidi needle on both sides of the pubic symphysis, approximately 8 mm from the joint surface (8 cm from the skin to the bone of the pubic symphysis) (Figs. 3-A and 3-B).

Fig. 3

Fig. 3

Then, a 5-mm cannulated Schanz screw (USS Fracture, Synthes) was placed over the guidewire under fluoroscopic control (Fig. 3-B) parallel to the pubic symphysis. The fracture clamps were slid over the Schanz screws and linked by a 6-mm titanium rod (USS Fracture, Synthes). A vertical reduction maneuver was used to anatomically restore the pubic symphysis (Fig. 4-A). Finally, in a first horizontal reduction maneuver, both Schanz screws were pulled laterally to allow a caudal compression of the symphysis, and the bolts were tightened (Fig. 4-B).

Fig. 4

Fig. 4

Subsequently, the adjunct bolts for lateral compression were loosened, and a second reduction maneuver compressed the fracture clamps, to also achieve cranial compression of the symphysis (Fig. 5). Final fluoroscopy demonstrated the good reduction and correct implant position. Suction drainage and stapler skin closure were performed. The postoperative radiography showed a sufficient reduction (Figs. 6-A, 7-A, and 8-A). Thereafter, the Schanz screws were cut, and the soft tissue was closed.

Fig. 5

Fig. 5

Fig. 6

Fig. 6

Fig. 7

Fig. 7

Fig. 8

Fig. 8

The patient was mobilized on the first postoperative day with no weight-bearing restrictions and released to rehabilitation on day 13. Follow-ups were at 6 and 12 months postoperatively. She showed no loss of function compared with her condition before the accident and reported to walk freely as before. There was also no pain in the symphyseal area. The Short-Form-Health-Survey-12 (SF-12) score was assessed, yielding a score of 31 points. Radiographs at 6 and 12 months postoperatively showed no signs of secondary displacement or implant failure (Figs. 6-B, 7-B, and 8-B).

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Discussion

Stabilization of the pubic symphysis using plate fixation, after open book injuries, is considered to be the current gold standard. Therefore, 4.5- or 3.5-mm dynamic compression plate (DCP) steel plates or locking plates are commonly used. These implants seem to enhance the outcome of patients after symphyseal disruption5. Yet for both the implants, complications such as screw loosening and implant breakage have been observed11,13. Although alternative minimally invasive stabilization techniques (e.g., INFIX, Pelvic Bridge, Cannulated Screws) have been described to stabilize the anterior pelvic ring in the literature, none have replaced the current plate osteosynthesis so far1,8-11,14-17. Although the Pelvic Bridge and the INFIX are both used as minimally invasive techniques, the length and size of the hardware compared with the technique described in this Case Report are larger and may cause more irritation. Although the Pelvic Bridge had been described in 2012, there are only a few reports found in the literature so far15,17. The described technique in our Case Report and the Pelvic Bridge both use the advantage of the pubic tubercles for fixation and stability. However, our technique only requires less dissection of the soft tissue because the implants are limited to the local parasymphyseal region.

The usual INFIX has been used in some studies with good results, but some complications such as femoral nerve palsy and massive irritations have also been reported16,18,19.

To achieve a stable stabilization of the symphysis pubis, Gonzálvez et al. showed that a minimal invasive stabilization technique using cannulated screws is biomechanically even superior to standard plate fixation. Furthermore, Osterhoff et al. showed a higher biomechanical rigidity of an internal fixator used parallel to the symphysis. Yet these techniques are limited because they do not allow a vertical reduction as required and are performed, in this case, using the internal fixator.

In our case, because of the patient's obesity and a higher risk of wound healing disorders, we decided to try a new minimally invasive technique. We decided to perform a modified stabilization technique using an internal fixator (USS Fracture; Synthes), which has already been established in spinal surgery15-17. Internal fixators used for pelvic surgery provide comparable challenging biomechanical requirements as in spinal surgery7,8,10,20. The patient consented to the novel, individualized procedure.

The small incision was adapted to the commonly used Pfannenstiel incision for symphyseal plating, yet with only 5 cm length. The pubic symphysis was 8 cm deep in the soft tissue, and both sides of the symphysis had to be prepared through slit incisions of the fascia. Regarding the distinct soft tissue, the incision was considered as a minimally invasive technique in this case because we would have needed an extensive approach of at least 15 cm for a conventional open plate fixation. In an athletic patient, the size of the approach would not make a large difference compared with the usual Pfannenstiel incision. The approach does not require the extended incision through the fascial layer and detachment of the rectus muscle for the plate fixation to reduce soft-tissue damage. In addition, the incision through the fascial layer for the placement of the plate and screw fixation can cause further soft-tissue damage, increasing the risk of wound complications. This approach also avoids encroaching on the femoral canal with already reported femoral nerve damage caused by INFIX stabilization21.

Using the intraoperative fluoroscopy, an adequate reduction and stabilization were feasible. The handling technique was performed according to the standard stabilization technique for spinal fractures7. The postoperative radiographs and CT scan showed an adequate reduction. Mobilization and release from the hospital were comparable to the standard technique. After 6 months, the patients' quality of life was comparable to that obtained after the standard procedure. Although irritations due to the prominence of the implant have been described for spinal injuries and the usage of INFIX11,18, the patient had no pain-related problems with the internal fixator. The patient was able to sit and had no pain in the clinical follow-up. Athletic patients may have pain-related symptoms, due to the size of the implant, these problems have been reported in patients treated with an INFIX in several studies, which often requires a second surgery with hardware removal18. Raman et al. reviewed 482 reported cases, with a retention rate of 7.5%, most of which were due to infection. They further stated that there is no consensus on whether symphyseal implants should be removed19. Despite the high stress on the implant through weight bearing of the morbidly obese patient, no loss of reduction was seen at the final follow-up (Figs. 68). In the future, advanced outcome measurement techniques could be used to further determine the patient's outcome in detail22.

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Conclusion

Thus far, there are scarce reports in the literature about the use of spinal internal fixators to stabilize pelvic injuries. Notably, pedicle screw and rod systems from spinal surgery have been described and successfully used as alternatives to pelvic external fixators, reaching broadly from one anterior-inferior iliac spine to the other11,12. In contrast, and hereby reported for the first time, the very local use of this type of implant on the symphysis in cases of disruption (open book injuries) seems to spare soft-tissue lesions and has better biomechanical effects acting in the region of interest. In addition, the series of implant handling maneuvers with the help of the long lever of the Schanz screws, as well as the sliding over the rod for better compression, simplifies the overall reduction during the course of the operation. As shown in this case, the use of an internal fixator for the stabilization of the pubic symphysis is an effective alternative to the standard plate fixation as a new minimally invasive stabilization option. To date, we could not observe disadvantages of the internal fixator compared with the standard plate stabilization; however, it allows a minimally invasive technique. Future biomechanical and clinical studies will be necessary to definitely evaluate the advantages of this new stabilization method.

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References

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