The bikini area and bikini line as a location for anterior subcutaneous pelvic fixation: An anatomic and clinical investigation

Identification of safe channels for screws in the anterior pelvic ring fixation system

Background

Minimally invasive surgery for pelvic fracture using anterior ring internal fixator system is increasing gradually, and the way to insert the fixation screws in the fixation system is the key technical points of the method. However, there have been few studies on insertion of fixation screws for the anterior pelvic ring internal fixator system.

Objective

To identify safe channels for fixation screws in the anterior pelvic fixator system and provide the anatomical basis for insertion of fixation screws in clinical operation.

Methods

Screw insertion was simulated into a total of 40 pelvic finite element models as well as 16 fresh pelvic specimens, and the channel parameters were measured.

Results

Finite elements (male, female) include: screws in ilium: length 114.4 ± 4.1 and 107.6 ± 8.3 mm, respectively; diameter 11.7 ± 0.5 and 10.0 ± 0.6 mm, distance between screw and anterior inferior iliac spine: 5.5 ± 1.0 and 5.6 ± 1.0 mm, angle of coronal plane 55.8° ± 2.4° and 50.6° ± 3.1°, angle of sagittal plane 26.6° ± 1.0° and 24.5° ± 1.9° and angle of horizontal plane 64.9 ± 3.7 and 58.1 ± 3.1; screws in pubis: length 47.0 ± 2.0 and 39.8 ± 3.9 mm, diameter 7.1 ± 0.4 and 6.1 ± 0.4 mm. Specimens (male, female) include: distance between screw and anterior inferior iliac spine: 5.5 ± 0.5 and 5.6 ± 0.7 mm, angle of coronal plane 55.9° ± 1.3° and 50.7° ± 1.5°, angle of sagittal plane 26.7° ± 0.5° and 24.1° ± 0.9° and angle of horizontal plane 64.8° ± 0.6° and 58.8° ± 0.8°. In the comparison between female and male in each group, differences in distances between screws and anterior inferior iliac spine and median line of symphysis pubis (P > 0.05) were not statistically significant; differences in the remaining parameters were statistically significant (P < 0.05).

Conclusions

If surgeons paid attention to sex differences, select screws of appropriate diameter and length and hold the insertion position and direction, screws in the anterior pelvic ring fixation system could be safely inserted.

Variability in rod to bone distance needed in pelvic subcutaneous internal fixation to avoid nerve compression: A tridimensional population-based study

INTRODUCTION

Pelvic internal fixation has become a popular method for treatment of unstable pelvic ring injuries. Although successful, one complication is femoral nerve palsy from compression of the connecting rod. In light of this complication, this study was designed to evaluate sagittal inclinations of the rod and the feasibility of using a rod with a constant curvature.

HYPOTHESIS

It is hypothesized that that there is a connection between the sagittal inclination of the rod and the rod to bone distance, as well as single rod can be contoured with a constant curvature to be used in the majority of all patients.

METHODS

Three dimensional models of pelvis CTs from a single level 1 trauma center were created and imported into a program where software superimposed a pre-contoured rod in the sagittal planes upon the pelvic slices. The sagittal inclination was deemed acceptable is no interference occurred between the area of compression risk and the rod. For each pelvis and considered sagittal rod inclination, the rod radius of curvature (ROC), minimal rod to bone distance (RTB) and transverse inclinations (φ_L and φ_R) were measured at which the pedicle screws should be inserted to follow the direction of the smallest RTB.

RESULTS

The sagittal inclinations feasible for all subjects were between 15° to 30°. In this sagittal range, the average RTB varied in values ranging from 4.0±0.9mm to 25.4±11.4mm (p<0.01). Only 46% of subjects allowed a rod with constant curvature.

DISCUSSION AND CONCLUSION

Our study found that a rod to bone distance of 15mm was not safe for all models. As well, many subject models did not allow placement of pre-contoured rod. Patient specific templating of pelvic subcutaneous internal fixation is strictly needed to limit complications.

LEVEL OF EVIDENCE

VII; Basic Science.

Clinical application of anterior ring internal fixator system combined with sacroiliac screw fixation in Tile C pelvic fracture treatment

Background

How to perform minimally invasive surgery for Tile C pelvic fracture is a major problem in clinical practice. We performed minimally invasive surgery for Tile C pelvic fracture using anterior ring internal fixator systems combined with sacroiliac screw fixation.

Objective

To investigate the advantages and efficacy of anterior ring internal fixator systems combined with sacroiliac screw fixation in the treatment of Tile C pelvic fracture.

Methods

From May 2017 to May 2020, 27 patients with Tile C pelvic fracture who underwent anterior ring internal fixator system combined with sacroiliac screw fixation (group A) and 21 patients with Tile C pelvic fracture who underwent plate-screw system combined with sacroiliac screw fixation (group B) were retrospectively analyzed.

Results

All 48 patients were followed up for more than 12 months, all fractures healed within 3–6 months. The operative time, intraoperative bleeding volume, blood transfusion volume, incision length, hospital stay, complication rate and Majeed score were 63.5 ± 10.7 min, 48.3 ± 27.9 ml, 0 ml, 4.5 ± 0.8 cm, 10.2 ± 2.7 d, 3.7% and 89.7 ± 4.6 points, respectively, in group A and 114.8 ± 19.1 min, 375 ± 315.8 ml, 266.7 ± 326.6 ml, 9.2 ± 3.9 cm, 20.9 ± 5.7 d, 23.8% and 88.7 ± 4.9 points, respectively, in group B. Combined excellent and good rates of the Matta evaluation and Majeed score were 100% in both groups. There were no significant differences in the Matta evaluation or Majeed score between the two groups (both P > 0.05), whereas the operative time, intraoperative bleeding volume, blood transfusion volume, incision length and hospital stay were significantly less in group A (all P < 0.05).

Conclusion

An anterior ring internal fixator system combined with sacroiliac screw fixation can effectively treat Tile C pelvic fracture, and has advantages, including minimal invasiveness, simple operation, short operative time, safe and reliable features, fewer complications, short hospital stay and a good curative effect.

Functional outcomes of the anterior subcutaneous internal pelvic fixator (INFIX) technique for pelvic ring injuries: A case series

INTRODUCTION

Anterior external fixation is a well-established technique for treating pelvic ring injuries, but many complications are associated with it. The subcutaneous anterior internal fixator (INFIX) technique is associated with reduced complication rates and is less uncomfortable for patients.

OBJECTIVE

This study evaluated functional outcomes among patients with pelvic ring injuries treated using the INFIX method.

PATIENTS AND METHODS

In this retrospective case series, patients treated using the INFIX technique were reviewed for functional outcomes, using the Iowa Pelvic Score (IPS). Thirty-four patients, of mean age 39.2 years, were evaluated after a mean follow-up of 1.2 years.

RESULTS

Twenty-three of the 34 patients experienced reduction classified as excellent, and eleven as good, with no instances of moderate or poor reduction. One patient developed implant exposure and infection during follow-up. Twenty-six ultimately experienced an excellent or good functional result. The average final IPS was 79.4 (range: 48-100).

CONCLUSION

Our results reinforce prior evidence that the INFIX method is safe for fixating pelvic ring lesions. Most of our patients also experienced excellent or good functional recovery, suggesting that this technique is a viable option for treating certain pelvic ring injuries.

[Research progress on minimally invasive treatment of anterior pelvic ring fracture]

OBJECTIVE

To summarize the related research results of minimally invasive treatment of anterior pelvic ring fracture, and to improve the understanding of minimally invasive treatment of anterior pelvic ring fracture.

METHODS

The literature of minimally invasive treatment of anterior pelvic ring fracture at domestic and overseas in recent years was reviewed, and the reduction and fixation methods of minimally invasive treatment were summarized and analyzed.

RESULTS

The pelvic reduction frame may be an effective auxiliary method for minimally invasive reduction of pelvis. The fixation methods of anterior pelvic ring include percutaneous screw fixation, stent fixation, and percutaneous plate fixation.

CONCLUSION

One kind of fixation is not applicable to all types of anterior pelvic ring fracture, and the fixation method should be selected according to the type of fracture and the patient's condition to minimize the complications.

The Anterior Subcutaneous Pelvic Ring Fixator: No Biomechanical Advantages Compared with External Fixation

BACKGROUND

Subcutaneous fixation of the anterior pelvic ring is an emerging surgical technique for trauma patients. The aim of this study was to biomechanically evaluate 2 internal fixation devices for stabilizing a disrupted pelvic ring and compare them with traditional external fixation.

METHODS

Thirty-six synthetic pelvises with a simulated unstable ring fracture (anteroposterior compression type III) were divided into 3 groups. Group A underwent fixation with a supra-acetabular external fixator; group B, with an internal fixator using the USS II polyaxial system; and group C, with an internal fixator using the Click'X polyaxial system. Biomechanical testing included measurement of peak-to-peak displacement at 300, 400, and 500 N; total displacement; plastic deformation; stiffness; and fracture-line displacement.

RESULTS

Statistical analysis of all measured parameters revealed no significant differences among the groups. However, vertical displacement of the preshaped connecting rod within the screw heads occurred as a result of inadequate stability of the internal fixation at the rod-screw interface.

CONCLUSIONS

Although internal fixator devices are placed close to the bone and should therefore maintain greater stiffness, our data did not support the hypothesis of superior stability. Special attention is required when using a curved connecting rod as the rod is easily displaced, placing relevant anatomical structures at risk. These devices require further refinement to avoid potential patient injury.

Safe Supra-Acetabular Pin Insertion in Relation to Intraosseous Depth

In pelvic fractures, dysfunction of the pelvic ring is often stabilized with supra-acetabular pin insertion. In existing literature, there are heterogeneous indications on proper pins selection and inclinations. Therefore, this study aimed to quantify the narrowing of safe pin corridors in the transverse and sagittal planes with increments of intraosseous screw depths. A computer algorithm created cross-sections over three-dimensional pelvic reconstructions at sagittal inclinations from 45° cranial to 45° caudal in 5° increments. Templates of screw depths spanning 60-120 mm in 15 mm increments were disposed in the transverse plane from 45° medial to 45° lateral. Each intraosseous screw depth and transverse angle were evaluated for intraosseous containment to evaluate ranges narrowing with increasing screw depths. The 60-mm depth resulted in the largest sagittal range (60.9° ± 6.9°) and transverse range (27.5° ± 4.1°) at 30° caudal. Increasing depths by 15 mm resulted in ranges being significantly different from one another (p < 0.01). The sagittal plane of 20° cranial had the highest frequency of insertion for all depths, while transverse ranges were narrowed (p < 0.01). Bisecting angles were similar for sagittal planes 20° cranial to 30° caudal with an average of 27.9° ± 1.2° (p ≥ 0.115). In conclusion, while 60 mm depths can be inserted with the highest discretion, 15 mm increments in depth significantly reduce safe ranges. Screws depths above 90 mm have low frequencies of insertion, should be inserted more cranially and must be considered prone to breaching. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 37:1790-1797, 2019.

INFIX/EXFIX: Innovation managing pelvic fractures in difficult scenarios

Pelvic fractures complicated by the presence of visceral injuries, open fractures and urethral or bladder injuries pose a significant challenge to treat. In these conditions internal fixation is usually contraindicated. External fixators, though a potential solution, have disadvantages like loss of reduction, pin tract infection and loosening. INFIX, a novel technique has been effective in managing anterior ring fractures and can be used as a substitute for internal fixation. We describe use of INFIX as EXFIX in three case scenarios where passing INFIX rod internally was precluded with favorable outcomes.

Modified internal fixator for anterior pelvic ring fractures versus conventional two-screw fixation

PURPOSE

The present study aims to evaluate the short-term clinical effects and complications of modified three-screw fixation and conventional two-screw fixation for treating anterior pelvic ring fractures.

METHODS

A retrospective study of 51 patients with type B fractures was performed. 25 patients (modified group) were treated with modified three-screw fixation and the other 26 patients (conventional group) with conventional two-screw fixation. Outcome measures included operation time, intraoperative blood loss, hospital stays, postoperative complications and the Majeed score at postoperatively 2 months, 3 months, 1 year and the time of implant removal.

RESULTS

The mean operative times and mean blood loss for modified three-screw fixation versus conventional two-screw fixation bilateral were 54.8 ± 10.7 min versus 32.3 ± 9.9 min, and 153.3 mL versus 550.0 mL (p < 0.001), respectively. However, the Majeed score was better in modified group at postoperatively 2 months (75.6 ± 9.5 vs. 69.7 ± 8.3, p = 0.008) and 3 months (80.3 ± 10.7 vs. 75.1 ± 11.9, p = 0.014). There was no statistical difference between two groups at the time of implant removal (82.1 ± 9.3 vs. 80.9 ± 8.8, p = 0.272) and postoperatively 1 year (83.5 ± 7.8 vs 82.6 ± 8.2, p = 0.723). No patients experienced surgical wound infection, deep vein thrombosis, delayed union or nonunion, implant loosening or rupture. One patient complained of tardive unilateral thigh pain at postoperatively 4 months in conventional group.

CONCLUSIONS

Both modified three-screw fixation and conventional two-screw fixation could ultimately afford satisfactory clinical and radiological outcomes with less complication for anterior pelvic ring fractures. The modified three-screw fixation might have better biomechanical strength and faster pelvic rehabilitation.

Anterior Subcutaneous Internal Pelvic Fixation/INFIX: A Systemic Review

INTRODUCTION

The purpose of this article is to review the available literature on anterior subcutaneous internal pelvic fixation (ASIPF) to identify indications, clinical and radiographic outcomes, and compare these with alternative fixation methods.

METHODS

Using the Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines, a systematic search on PubMed and Google Scholar was performed. Articles included were in the English language or English translations and published between 2007 and 2018. Studies included were appraised with narrative data synthesis.

RESULTS

Twenty-five articles with 496 patients were included. These included 17 case series, with 3 case reports reporting adverse events.

CONCLUSIONS

ASIPF and the appropriate posterior fixation resulted in healing of pelvic ring injuries in 99.5% of cases. Indications include unstable pelvic ring injuries with the appropriate posterior fixation. Radiographic parameters and outcome measures were infrequently reported. ASIPF is a valuable tool for reduction and fixation in unstable pelvic ring injuries. Complications include lateral femoral cutaneous nerve irritation (26.3%); heterotopic ossification (36%); infection (3%); and femoral nerve palsy (1%), which is likely related to placing the bar and screws too deep.

Minimally invasive anterior pelvic internal fixation: An anatomic study comparing Pelvic Bridge to INFIX

OBJECTIVES

Anterior external fixation for pelvic ring fractures has shown to effectively improve stability and reduce mortality. However, these fixators can be associated with substantial morbidity such as pin tract infection, premature loss of fixation, and decreased quality of life in patients. Recently, two new methods of subcutaneous anterior pelvic internal fixation have been developed; the INFIX and the Pelvic Bridge. These methods have the purported advantages of lower wound complications, less surgical site pain, and improved quality of life. We sought to investigate the measured distances to critical anatomic structures, as well as the qualitative and topographic differences notable during implantation of both devices in the same cadaveric specimen.

MATERIALS AND METHODS

The Pelvic Bridge and INFIX were implanted in eleven fresh cadavers. Distances were then measured to: the superficial inguinal ring, round ligament, spermatic cord, lateral femoral cutaneous nerve (LFCN), femoral nerve, femoral artery, and femoral vein. Observations regarding implantation and topography were also recorded.

RESULTS

The INFIX had greater measured distances from all structures except for the LFCN, in which its proximity placed this structure at risk. Neither device appears to put other critical structures at risk in the supine position. Significant implantation and topographic differences exist between the devices. The INFIX application lacked "safety margins" concerning the LFCN in 10/11 (90.9%) specimens, while Pelvic Bridge placement lacked "safety margins" with regard to the right superficial ring (1/11, 9%) and the right spermatic cord (1/11, 9%).

CONCLUSIONS

Both the Pelvic Bridge and INFIX lie at safe distances from most critical pelvic structures in the supine position, though INFIX application places the LFCN at risk.

Anterior subcutaneous internal fixation of the pelvis - what rod-to-bone distance is anatomically optimal?

INTRODUCTION

Anterior fixation of the pelvis using subcutaneous supra-acetabular pedicle screw internal fixation (INFIX) has proven to be a useful tool by avoiding the downsides of external fixation in patients where open fixation is not suited. The purpose of this study was to find a rod-to-bone distance for the INFIX that allows for minimal hazard to the inguinal neuro-vascular structures and, at the same time, as little as possible interference with the soft tissues of the proximal thigh when the patient is sitting.

METHODS

An INFIX was applied to 10 soft-embalmed cadaver pelvises with three different rod-to-bone distances. With each configuration, the relations of the rod to the neuro-vascular and the muscular surroundings were measured in supine and sitting position.

RESULTS

Except for the femoral artery, vein and nerve, all investigated anatomical structures of the groin were under compression with a rod-to-bone distance of 1cm. With a rod-to-bone distance of 2cm most of the anatomical structures were safe in supine position, although less than with 3cm. With hip flexion some structures got under compression, especially the lateral femoral cutaneous nerve (LFCN, 80%) and the anterior cutaneous branches of the femoral nerve (ACBFN, 35%). With a rod-to-bone distance of 3cm almost all anatomical structures were safe in supine position, while with hip flexion most superficial structures of the proximal thigh got under compression, especially the LFCN (75%) and the ACBFN (60%).

CONCLUSIONS

Aiming for a rod-to-bone distance of 2cm is the safest way with regard to compression of the femoral neuro-vascular bundle and at the same time leads to the least compression of more superficial structures like the LFCN, the ACBFN, or the sartorius and the rectus femoris muscles in sitting position.

Minimally invasive treatment of unstable pelvic ring injuries with modified pedicle screw-rod fixator

Objective

To evaluate the clinical application of the minimally invasive modified pedicle screw–rod fixator for unstable pelvic ring injuries, including its feasibility, merits, and limitations.

Methods

Twenty-three patients (13 males, 10 females; average age, 36.3 years) with unstable pelvic ring injuries underwent anterior fixation using a modified pedicle screw–rod fixator with or without posterior fixation using a transiliac internal fixator. The clinical findings were assessed using Majeed scores. The quality of reduction was evaluated using the Matta criteria.

Results

Clinical results at 1 year postoperatively were excellent in 14 patients, good in 7, and fair in 2. The two patients with fair results had intermittent pain at the sacroiliac joint because of the posterior implant. One woman complained of persistent pain at the pubic tubercle during sexual intercourse. Iatrogenic neuropraxia of the unilateral lateral femoral cutaneous nerve occurred in three patients. Unilateral femoral nerve palsy occurred in one patient. The quality of fracture reduction was excellent in 12 patients, good in 8, and fair in 3. Heterotopic ossification occurred in eight patients; all were asymptomatic.

Conclusions

Minimally invasive modified pedicle screw-rod fixation is an effective alternative treatment for pelvic ring injuries.

Optimization of technique for insertion of implants at the supra-acetabular corridor in pelvis and acetabular surgery

The technique for application of implants at the sciatic buttress has been well described in the pelvic and acetabular fracture reconstruction literature. We described a new use of the inlet–obturator oblique view for the identification of the anterior inferior iliac spine, which is the entry point of implants, and we provide a detailed fluoroscopic and radiographic description of this view. A small series of 15 patients who underwent an application of an anterior inferior pelvic external (supra-acetabular) fixator via this technique is presented. We consider the use of the obturator oblique for the identification of the entry point unnecessary, and we advocate for the use of only the inlet–obturator oblique and iliac oblique views when implants are applied to the sciatic buttress.

Modified pedicle screw-rod fixation as a minimally invasive treatment for anterior pelvic ring injuries: an initial case series

Background

Unstable pelvic ring injuries often involve high mortality and morbidity. This study was aimed to evaluate the modified minimally invasive pedicle screw–rod fixation for anterior pelvic ring injuries, in the respects of its feasibility, merits, and limitations.

Methods

Twenty-three patients with unstable pelvic ring injuries underwent the modified anterior pedicle screw–rod fixation, with or without posterior fixation. The clinical outcomes were assessed using Majeed scores, and the quality of reduction was evaluated according to the criteria of Matta.

Results

Majeed scores showed that the clinical outcomes at postoperatively 1 year were excellent in 14 patients, good in 7, and fair in 2. One woman complained of persistent pain at the pubic tubercle during sexual intercourse. Iatrogenic neuropraxia of the unilateral lateral femoral cutaneous nerve occurred in 3 patients. Unilateral femoral nerve palsy occurred in 1 patient. The reduction was found to be excellent in 12 patients, good in 8, and fair in 3. Heterotopic ossification occurred in 8 patients, all being asymptomatic.

Conclusions

The modified pedicle screw–rod fixation with the minimally invasive technique offered an effective alternative for unstable anterior pelvic ring injuries.

Midterm Radiographic and Functional Outcomes of the Anterior Subcutaneous Internal Pelvic Fixator (INFIX) for Pelvic Ring Injuries

OBJECTIVE

To describe our experience using the anterior internal pelvic fixator (INFIX) for treating pelvic ring injuries.

DESIGN

Case Series.

SETTING

Level 1 Trauma Center.

PATIENTS

Eighty-three patients with pelvic ring injuries were treated with INFIX. Follow-up average was 35 months (range 12-80.33).

INTERVENTION

Surgical treatment of pelvic ring injuries included reduction, appropriate posterior fixation, and INFIX placement.

OUTCOME MEASUREMENTS

Reduction using the pelvic deformity index and pubic symphysis widening, Majeed functional scores, complications; infection, implant failure, heterotopic ossification (HO), nerve injury, and pain.

RESULTS

All patients healed in an appropriate time frame (full weight bearing 12 weeks postoperation). The average pelvic deformity index reduction (injury = 0.0420 ± 0.0412, latest FU = 0.0254 ± 0.0243) was 39.58%. The average reduction of pubic symphysis injuries was 56.92%. The average Majeed score of patients at latest follow-up was 78.77 (range 47-100). Complications were 3 infections, 1 case of implant failure, 2 cases implantation too deep, 7 cases of lateral femoral cutaneous nerve irritation, and 3 cases of pain associated with the device. HO was seen in >50% of the patients, correlated with increased age (P < 0.007), injury severity score (P < 0.05) but only 1 case was symptomatic.

CONCLUSIONS

The pelvic injuries had good functional and radiological outcomes with INFIX and the appropriate posterior fixation. The downside is removal requiring a second anesthetic, there is a learning curve, HO often occurs, the lateral femoral cutaneous nerve may get irritated which often resolves once the implants are removed. Surgery-specific implants need to be developed.

LEVEL OF EVIDENCE

Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

"Anterior subcutaneous pelvic internal fixator (INFIX), Is it safe?" A cadaveric study

INTRODUCTION

Anterior pelvic internal fixator (INFIX) is used to treat unstable pelvic ring injuries. Nerve injury complications with this procedure have been reported.

OBJECTIVES

This anatomic study attempted to identify structures at risk after application of INFIX.

MATERIALS AND METHODS

INFIX was applied in fifteen fresh, frozen, anatomical specimens using polyaxial pedicular screws and subcutaneous rods. Surgical dissection was done to identify the structures at risk including the femoral nerve (FN), femoral artery (FA), femoral vein (FV) and the lateral femoral cutaneous nerve (LFCN) related to which are potentially affected by the implant.

RESULTS

All structures at risk were closer to the rod than to the pedicular screw. Measurements were made between the rod and the structures at risk. The LFCN was an average of 13.49±1.65mm (95% CI 12.871-14.103) from the lateral end of the rod. The FN was an average of 12.43±3.42mm (95% CI 11.151-13.709), the FA was an average of 12.80±3.67 (95% CI 11.430-14.173) and the FV was an average of 13.48±3.73 (95% CI 12.082-14.871) below the rod. No direct compression of the rod to the structure at risk was observed.

CONCLUSIONS

The femoral nerve is the structure most at risk of compression by the INFIX rod. Careful surgical technique is required in every step of this surgery. We suggest using polyaxial screws and recommend that during screw insertion the surgeon should leave some space between the screw and rectus fascia. The the rod should be trimmed as short as possible to reduce LFCN irritation.

The Anterior Subcutaneous Pelvic Fixator (INFIX) in an Anterior Posterior Compression Type 3 Pelvic Fracture

OBJECTIVES

The purpose of this video is to describe the equipment, anatomy, and surgical technique of anterior subcutaneous pelvic fixation (INFIX) using pedicle screws and a rod in an Anterior Posterior Compression 3 pelvic fracture, as well as how to distract in lateral compression fractures.

METHODS

The equipment required includes standard spine pedicle screw sets with long screws, 70-110 mm in length, and 7 or 8 mm in diameter. The approach is a mini open and one needs to be familiar with the iliac oblique, obturator outlet, and obturator inlet views. The length of the screw is measured from the sciatic notch to the skin, and they are placed so that the head sits just below the skin. The rod is passed just under the skin along the bikini line and the construct compressed or distracted against a c-clamp while monitored with fluoroscopy. In Orthopaedic Trauma Association C type injuries, we leave c-clamps on the outside the screws to reinforce them or use monoaxial screws. The implants are removed at 3-6 months postop.

RESULTS

The patients tolerate the implants and are able to sit and stand with out difficulty. Complications include lateral femoral cutaneous nerve irritation, heterotopic bone, loss of fixation if the implants are applied incorrectly.

CONCLUSIONS

The INFIX procedure for anterior pelvic fixation is based on standard techniques that are familiar to the Orthopaedic Pelvic Surgeon including supraacetabular screws. Rod bending, rod passing, determining the ideal height of the screws, and distraction/compression maneuvers are demonstrated in this video.

INFIX/EXFIX: Massive Open Pelvic Injuries and Review of the Literature

Introduction. Open pelvic fractures make up 2–5% of all pelvic ring injuries. Their mortality has been reported to be as high as 50%. During Operation Enduring Freedom protocols for massive open pelvic injuries lead to the survival of injuries once thought to be fatal. The INFIX is a subcutaneous anterior fixator for pelvic stabilization which is stronger than external fixation. The purpose of this paper is to describe the use of INFIX and modern algorithms for massive open pelvic injuries. Methods. An IRB approved retrospective review describes 4 cases in civilian practice with massive open pelvic injuries. We also review the modern literature on open pelvic injures. Discussion. Key components in the care of massive open pelvic injuries include hemorrhage control by clamping of the aorta or REBOA when necessary and fecal/urinary diversion. The INFIX can be used internally, as a partial INFIX partial EXFIX, or as an EXFIX. Its low profile allows for easy application of wound vacs and wound care and when subcutaneous avoids pin tract infections. Conclusion. Massive open pelvic injuries are a difficult problem. Following modern protocols can help prevent mortality.

Minimally-invasive fixation for anterior pelvic ring disruptions

Pelvic fractures are usually the result of high-energy trauma. In addition to the underlying disruption of the pelvic ring extensive damage to the surrounding soft tissue envelope might be present. Different fixation techniques have been developed including open plating, external fixation and transramus intraosseous screw fixation. Recently another method has been reported the so called pelvic Bridge or Infix technique. In this short review article the different techniques of pelvic fixation are described.

A biomechanical study of standard posterior pelvic ring fixation versus a posterior pedicle screw construct

OBJECTIVES

The purpose of this study was to biomechanically test a percutaneous pedicle screw construct for posterior pelvic stabilisation and compare it to standard fixation modalities.

METHODS

Utilizing a sacral fracture and sacroiliac (SI) joint disruption model, we tested 4 constructs in single-leg stance: an S1 sacroiliac screw, S1 and S2 screws, the pedicle screw construct, and the pedicle screw construct+S1 screw. We recorded displacement at the pubic symphysis and SI joint using high-speed video. Axial stiffness was also calculated. Values were compared using a 2-way ANOVA with Bonferroni adjustment (p<0.05).

RESULTS

In the sacral fracture model, the stiffness was greatest for the pedicle screw+S1 construct (p<0.001). There was no significant difference between the pedicle screw construct and S1 sacroiliac screw (p=1). For the SI joint model, the S1+S2 SI screws had the largest overall load and stiffness (p<0.001). The S1 screw was significantly stronger than pedicle screw construct (p=0.001).

CONCLUSIONS

The pedicle screw construct biomechanically compares to currently accepted methods of fixation for sacral fractures when the fracture is uncompressible. It should not be used for SI joint disruptions as one SI or an S1+S2 are significantly stiffer and cheaper.

Femoral nerve palsy after pelvic fracture treated with INFIX: a case series

OBJECTIVE

The treatment of some pelvic injuries has evolved recently to include the use of a subcutaneous anterior pelvic fixator (INFIX). We present 8 cases of femoral nerve palsy in 6 patients after application of an INFIX to highlight this potentially devastating complication to pelvic surgeons using this technique and discuss how it might be avoided in the future.

DESIGN

Retrospective chart review. Case series.

SETTING

Five level 1 and 2 trauma centers, tertiary referral hospitals.

PATIENTS/PARTICIPANTS

Six patients with anterior pelvic ring injury treated with an INFIX who experienced 8 femoral nerve palsies (2 bilateral).

INTERVENTION

Removal of internal fixator, treatment for femoral nerve palsy.

MAIN OUTCOME MEASUREMENTS

Clinical and electromyographic evaluation of patients.

RESULTS

All 6 patients with a total of 8 femoral nerve palsies had their INFIX removed. Variable resolution of the nerve injuries was observed.

CONCLUSIONS

Application of an INFIX for the treatment of pelvic ring injury carries a potentially devastating risk to the femoral nerve(s). Despite early implant removal after detection of nerve injury, some patients had residual quadriceps weakness, disturbance of the thigh's skin sensation, and/or gait disturbance attributable to femoral nerve palsy at the time of early final follow-up.

LEVEL OF EVIDENCE

Therapeutic level IV. See Instructions for Authors for a complete description of levels of evidence.

Anterior subcutaneous internal fixation for treatment of unstable pelvic fractures

BACKGROUND

Fractures of the pelvic ring including disruption of the posterior elements in high-energy trauma have both high morbidity and mortality rates. For some injury pattern part of the initial resuscitation includes either external fixation or plate fixation to close the pelvic ring and decrease blood loss. In certain situations--especially when associated with abdominal trauma and the need to perform laparotomies--both techniques may put the patient at risk of either pintract or deep plate infections. We describe an operative approach to percutaneously close and stabilize the pelvic ring using spinal implants as an internal fixator and report the results in a small series of patients treated with this technique during the resuscitation phase.

FINDINGS

Four patients were treated by subcutaneous placement of an internal fixator. Screw fixation was carried out by minimally invasive placement of two supra-acetabular iliac screws. Afterwards, a subcutaneous transfixation rod was inserted and attached to the screws after reduction of the pelvic ring. All patients were allowed to fully weight-bear. No losses of reduction or deep infections occurred. Fracture healing was uneventful in all cases.

CONCLUSION

Minimally invasive fixation is an alternative technique to stabilize the pelvic ring. The clinical results illustrate that this technique is able to achieve good results in terms of maintenance of reduction the pelvic ring. Also, abdominal surgeries no longer put the patient at risk of infected pins or plates.

Monoaxial pedicle screws are superior to polyaxial pedicle screws and the two pin external fixator for subcutaneous anterior pelvic fixation in a biomechanical analysis

Purpose. Comparison of monoaxial and polyaxial screws with the use of subcutaneous anterior pelvic fixation. Methods. Four different groups each having 5 constructs were tested in distraction within the elastic range. Once that was completed, 3 components were tested in torsion within the elastic range, 2 to torsional failure and 3 in distraction until failure. Results. The pedicle screw systems showed higher stiffness (4.008 ± 0.113 Nmm monoaxial, 3.638 ± 0.108 Nmm Click-x; 3.634 ± 0.147 Nmm Pangea) than the exfix system (2.882 ± 0.054 Nmm) in distraction. In failure testing, monoaxial pedicle screw system was stronger (360 N) than exfixes (160 N) and polyaxial devices which failed if distracted greater than 4 cm (157 N Click-x or 138 N Pangea). The exfix had higher peak torque and torsional stiffness than all pedicle systems. In torsion, the yield strengths were the same for all constructs. Conclusion. The infix device constructed with polyaxial or monoaxial pedicle screws is stiffer than the 2 pin external fixator in distraction testing. In extreme cases, the use of reinforcement or monoaxial systems which do not fail even at 360 N is a better option. In torsional testing, the 2 pin external fixator is stiffer than the pedicle screw systems.