Value of 3D fluoroscopic imaging of acetabular fractures comparison to 2D fluoroscopy and CT imaging

Postoperative Computed Tomography Scans of Acetabular Fractures Routinely Identify Indications for Revision Surgery

OBJECTIVES

To investigate the utility of postoperative computed tomography (CT) scans in identifying indications for revision surgery after surgical fixation of acetabular fractures.

METHODS

DESIGN

Retrospective cohort study.

SETTING

Urban level 1 trauma center.

PATIENT SELECTION CRITERIA

Patients with surgically treated acetabular fractures with surgical fixation (open reduction and internal fixation or percutaneous fixation) with routine postoperative CT scans.

OUTCOME MEASURES AND COMPARISONS

Primary outcome-revision surgery based on postoperative imaging, including intra-articular osteochondral fragments, implant complications, and malreductions. Secondary outcome-quality of reduction on radiographs versus CT scans.

RESULTS

One hundred forty-eight patients were included. The revision surgery rate was 15.5% (23/148); indications included malpositioned implants (6.7%, n = 10), malreductions (5.4%, n = 8), and intra-articular loose bodies (3.4%, n = 5). Only 8.7% (2/23) of the indications for revision surgery were identified on postoperative radiographs, with the remainder being identified on CT scans. Revision surgeries were found to be associated with male gender (proportional difference: 19.6%, 95% confidence interval [CI]: 3.4%-29.4%; P = 0.04) and T-type fractures (PD 28.7%; CI, 9.0%-48.9%; P = 0.001). Revision surgery was not found to be associated with age, body mass index, posterior wall fractures, concurrent pelvic ring fractures, or surgical approach. On radiographs, 51.3% (n = 76/148) had anatomic reductions (<2 mm) compared with only 10.2% (n = 15/148) on CT scans.

CONCLUSIONS

Indications for revision of acetabular fixation surgeries and poor reductions were frequently missed on plain radiography and identified on postoperative CT scans. This suggests that the use of advanced imaging such as intraoperative 3D imaging or postoperative CT scans may be beneficial.

LEVEL OF EVIDENCE

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

Routine postoperative computed tomography (CT) scans following acetabulum open reduction internal fixation (ORIF): A survey of orthopaedic traumatologists

OBJECTIVE

The purpose of this study was to assess the practices related to obtaining postoperative pelvic CT scans following acetabular ORIF and revision surgery rates.

DESIGN

A 20-question survey published on the Orthopaedic Trauma Association (OTA) website assessed each surgeon's preference and rationale for or against the routine use of postoperative CT scans for acetabular fractures.

PARTICIPANTS

Fellowship-trained orthopaedic traumatologists.

MAIN OUTCOME MEASUREMENTS

We examined the percentage of surgeons ordering routine postoperative CT scans, surgeon demographics, and revision surgery rates based on these routine CT scan results.

RESULTS

Responses were received from 57 surgeons. Practices varied regarding postoperative CT scans, with 16 surgeons (28%, Group A) routinely ordering them and 41 surgeons (72%, Group B) not ordering them on all patients. No significant difference in surgeon demographics were found between the groups. Majority of Group A report a revision surgery rate of <1% based on the results of the postoperative CT. Group A report routine postoperative scans were obtained to assess reduction, hardware placement, identify intra-articular fragments, and for educational purposes. Group B did not obtain routine postoperative CTs due to the following: unlikely to change postoperative treatment, adequate reduction and instrumentation placement assessed intraoperatively and by postoperative radiographs, and increased radiation exposure and cost to patients. Group B did report obtaining postop CT scans on select patients, with inadequate intraoperative imaging and postoperative neurological changes being the most common indications.

CONCLUSION

The routine use of postoperative CTs following open reduction internal fixation of acetabular fractures is a controversial topic. While we recognize the role for postoperative CT scans in select patients, our study questions the clinical utility of these scans in all patients and in conclusion do not recommend this protocol.

[Imaging examination procedures, navigation and minimally invasive procedures in acetabular surgery]

Acetabular fractures still pose a special challenge even today. Considering the increasing case numbers, especially in the geriatric patient group, modern imaging examination procedures represent an essential pillar of the diagnostics. Especially in this vulnerable patient group, minimally invasive methods are necessary, which can be guaranteed by intraoperative navigation; however, the choice of surgical access and implants is also made based on the existing morphological characteristics of fractures, which highlights the importance of an imaging modality that is as detailed as possible. Last but not least, new developments concerning the surgical treatment of these injuries are also based on this. This article summarizes the current state of the techniques and the available literature.

Intraoperative revision rates due to three-dimensional imaging in orthopedic trauma surgery: results of a case series of 4721 patients

PURPOSE

Intraoperative 3D imaging has become a valued tool in assessing the quality of reduction and implant placement in orthopedic trauma surgery. In our institution, 3D imaging is used routinely since 2001. To evaluate the intraoperative findings and consequences of this technique, intraoperative revision rates in cases with 3D imaging were analyzed.

METHODS

All operative procedures carried out with intraoperative 3D imaging between August 2001 and December 2016 were included. The scans were assessed intraoperatively and documented thereafter. In case of malreduction or misplaced implants, an immediate revision was performed. The number of scans per case as well as the findings and consequences drawn regarding the anatomical region were analyzed.

RESULTS

4721 cases with 7201 3D scans were included in this study. The most common anatomical regions were the ankle (22.3%), the calcaneus (14.8%) and the tibial head (9.5%). In 19.1% of all cases, an intraoperative revision was performed. The highest revision rates were found with 36.0% in calcaneal fractures, 24.8% in fractures of the tibial plateau, 22.3% in injuries of the ankle. In 52.0% of revisions, the reduction was improved regarding intra-articular steps or joint congruency. In 30.5% an implant was corrected.

CONCLUSION

Intraoperative revision due to results of 3D imaging was performed in almost one-fifth of cases. This illustrates the improved possibilities to detect malreduction and implant misplacements intraoperatively and thus the abilities to improve surgical outcome.

LEVEL OF EVIDENCE

III.

Use of the Hybrid Operating Room for Pelvic and Acetabular Fracture Surgery

The hybrid operating room (HOR) utilizes advanced imaging technology to improve intra-operative visualization and facilitate efficient care in procedures that are relatively image dependent. The robotic C-arm provides improved 2D image quality and is capable of large volume three-dimensional fluoroscopy (3DF) that can rapidly create multiplanar CT like images. Here we discuss on the technique, utility, potential benefits, pitfalls, and complications of using the hybrid suite with and without intra-arterial balloon occlusion for pelvic and acetabular fracture surgery. We also present a case series of patient who underwent pelvic fixation using the HOR. While not advocated for routine use in all pelvic and acetabular fractures; the hybrid suite can be an effective tool in the treatment of complex cases and may facilitate efficient care of the hemodynamically unstable patient. It should be considered when resuscitative stabilization, angioembolization, intra-arterial balloon occlusion, or life-threatening bleeding is anticipated. Additionally, use of the hybrid room allows access to 3D fluoroscopy, and the associated benefits, if a mobile 3D unit is otherwise unavailable. These benefits must be weighed against the cumbersome table, the potential pitfalls with patient size and positioning, and the increased cost to the hospital.

Low interobserver and intraobserver reliability using the Matta radiographic system for intraoperative assessment of reduction following acetabular ORIF

INTRODUCTION

The system described by Matta for rating acetabular fracture quality of reduction following ORIF has been used extensively throughout the literature. However, the reliability of this system remains to be validated. We sought to determine the interobserver and intraobserver reliability of this system when used by fellowship-trained pelvic and acetabular surgeons to evaluate intraoperative fluoroscopy.

METHODS

This is a retrospective evaluation of a prospectively collected acetabular fracture database at an academic level I trauma center. The quality of reduction of all acetabular fractures treated with open reduction internal fixation (ORIF) between May 2013 and December 2015 was assessed using three standard intraoperative fluoroscopic views (anteroposterior and two 45˚ oblique Judets). Displacement of ≤1 mm was considered to be an anatomic reduction, 2-3 mm imperfect, and >3 mm poor according to the system described by Matta. A total of 107 acetabular fractures treated with ORIF with complete intraoperative fluoroscopic images during that time period were available for review. Acetabular fracture reductions were reviewed by the operative surgeon at the time of surgery and subsequently reviewed by two fellowship-trained pelvic and acetabular surgeons. All reduction assessments were performed in a blinded fashion. The primary outcome measure was interobserver reliability for assessing reduction quality. This was evaluated using a weighted kappa (κ_w) statistic between each evaluator and the operative surgeon and a generalized kappa (κ_g) for all 3 surgeons. After a 6-week "washout interval," the surgeons reviewed the images again and intraobserver agreement was calculated using a weighted kappa statistic.

RESULTS

Interobserver reliability based on the initial assessment was low (κ_g = 0.09); however, did slightly improve with the second assessment to fair (κ_g = 0.24). Intraobserver reliability ranged from slight (κ_w = 0.20) to moderate (κ_w = 0.53) among the surgeons.

DISCUSSION

Low interobserver and intraobserver reliability was found when quality of reduction was assessed with intraoperative fluoroscopic images by the operative and two other pelvic and acetabular surgeons using the Matta system. Given the importance of an anatomic reduction on functional and radiographic outcomes, an accurate and reliable system for assessing intraoperative quality of reduction is essential.

Utility of 3-Dimensional Intraoperative Imaging in Pelvic and Acetabular Fractures: A Network Meta-Analysis

BACKGROUND

Successful surgical management of pelvic ring and acetabular fractures requires technical expertise to achieve an accurate reduction and stable fixation. The use of 3-dimensional (3D) intraoperative imaging (3DIOI) as an assessment tool has led to improved reduction and placement of implants. The purpose of this study was to assess the utility of using 3DIOI in the management of acetabular and pelvic fractures on the basis of outcomes reported in the literature.

METHODS

A literature search was performed using PubMed, the Cochrane Database of Systematic Reviews (CDSR), and Google Scholar using key terms. A network meta-analysis conducted using the frequentist approach allowed for statistical analysis of reported outcomes regarding screw position (in mm), fracture reduction (in mm), and complications.

RESULTS

A total of 9 studies were included in this analysis. When compared with conventional radiography, the mean radiation dose (in cGy·cm2) was significantly higher in 3DIOI (mean difference, 82.72; 95% confidence interval [CI], 21.83 to 143.61; p = 0.007). Use of 3DIOI yielded a 93% lower risk of developing medical complications (odds ratio [OR], 0.07; 95% CI, 0.02 to 0.35; p = 0.014). Use of 3DIOI yielded higher odds of achieving accurate screw placement (OR, 4.21; 95% CI, 1.44 to 12.32; p = 0.008) and perfect reduction (OR, 2.60; 95% CI, 1.19 to 5.68; p = 0.016). In ranking the imaging modalities, 12 of the 13 parameters analyzed were in favor of 3DIOI over conventional fluoroscopy and 2D navigation imaging.

CONCLUSIONS

Current literature supports the use of 3DIOI because of the decreased rates of misplaced implants, malreduced fractures, complications, and subsequent revision operations. The use of 3DIOI allows for improved visualization of pelvic anatomy when repairing pelvic and acetabular fractures, and helps surgeons to achieve favorable surgical outcomes.

LEVEL OF EVIDENCE

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

Comparative study of anatomical locking plate and reconstruction plate in treating acetabular fractures

PURPOSE

This study aims to compare the effectiveness of anatomic locking plate and reconstruction plate used in treating acetabular fractures.

METHODS

From January 2009 to January 2016, patients with acetabular fractures were included in this retrospective study. We grouped the patients into two groups based on the internal fixation: reconstruction plate group (RPG) and anatomic locking plate group (ALPG). The operation time, blood loss, intra-operative screw penetration, and plate breakage were compared between the two groups. The intra-operative fluoroscopic images were used to evaluate the fixation location. The quality of reduction and radiological grading were assessed according to the criteria developed by Matta. The clinical assessment was based on the Merle d'Aubigne-Postel score.

RESULTS

Eighty-three patients were included in this study and were followed up for an average of 35 months (range, 25 to 42 months). Thirty-five patients were treated with the anatomical locking plate, and 48 patients were treated with the reconstruction plate. The mean surgical time was significantly shorter (P < 0.0001) in ALPG patients than in RPG patients, and the intra-operative blood loss was significantly lower (P = 0.008). The rates of intra-operative screw penetration or plate breakage in the ALPG (0/35) are significantly lower than that in the RPG (7/48) (P = 0.018). Post-operative Matta score (P = 0.905), Merle d'Aubigne-Postel score (P = 0.957), and overall complication rates (P = 0.391) were not significantly different among the groups.

CONCLUSION

Patients treated by anatomical locking plate had shorter operation time, less bleeding, and lower rate screw perforation compared to patients treated by reconstruction plate. Anatomical locking plate is a better choice for acetabulum fractures, especially complicated fractures.

Pelvic discontinuity in acetabular revisions: does CT scan overestimate it? A comparative study of diagnostic accuracy of 3D-modeling and traditional 3D CT scan

PURPOSE

3D CT scan is actually the gold standard for preoperative diagnosis of pelvic discontinuity (PD) in hip revision surgery. Aim of this study was to compare the accuracy of 3D-modeling with traditional and 3D CT scan.

MATERIALS AND METHODS

We retrospectively identified 56 patients who underwent total hip arthroplasty revisions with Paprosky Type-3 periacetabular bone defects. Preoperative X-rays, CT scans and 3D-models were blindly reviewed by two orthopedic surgeons to detect possible pelvic discontinuities. Results were compared with surgical notes. Independent sensitivities, specificities, positive predictive values and negative predictive values were calculated for X-rays, CT scan and 3D models. Analysis of interobserver reliability was performed.

RESULTS

Fifty-six patients met inclusion criteria. In nine patients, surgical notes indicated a pelvic discontinuity. On 3D CT scans, PD was identified in 25 cases for observer 1 and in 24 cases for observer 2. Analyzing 3D-models, PD was identified in eleven patients by both observers. The nine patients, with PD reported on the surgical report, were all identified with both the techniques. The specificity of standard 3D CT was 0.66 for observer 1 and 0.68 for observer 2 and increased to 0.96 for both observers with the utilization of 3D-models. The positive predictive value increased from 0.36 (observer 1) and 0.38 (observer 2) with the CT evaluation to 0.82 in the 3D-models evaluation. The analysis of 3D models was characterized by a perfect intraobserver reliability (intraobserver correlation coefficient = 1). The observers showed substantial agreement for PD classification; the kappa values were 0.96 and 0.77, respectively, for CT scan and 3D-model evaluation.

CONCLUSIONS

3D-modeling showed higher specificity than traditional and 3D CT scans in identification of PD in Paprosky Type-3 periacetabular bone defects.

Acetabular Lateral View: Effective Fluoroscopic Imaging to Evaluate Screw Penetration Intraoperatively

Background

Screw penetration into the hip joint is a severe complication during acetabular fracture surgery. The standard fluoroscopic views of the pelvis cannot provide adequate safety during screw insertion. The aim of this research was to determine and evaluate the accuracy of the acetabular lateral view for screw placement.

Material/Methods

Twenty screws were randomly chosen and intentionally penetrated into the articular surface (1–2 mm), and the remaining 20 screws were extra-articular ones positioned in close proximity to the articular surface. Three surgeons, each evaluating 40 screws, provided a total of 120 rated observations for each screw position. We compared the traditional view or combined with lateral acetabular view with the criterion standard based on unaided visual assessment. A blinded and independent review of each pelvic intraoperative fluoroscopy was made by 3 independent observers. Specificity, sensitivity, positive predictive value, negative predictive value, correct interpretation, intra-class correlation coefficients (ICC), and Youden index were calculated.

Results

There were significant differences in sensitivity, NPV, correct interpretation, and Youden index between the 2 groups (P<0.05). The ICC was 0.531 when the antero-posterior, iliac, and obturator oblique views were used. The ICC was remarkably increased when using a combination of the „lateral” view and the standard views for screw perforation of the joint.

Conclusions

Use of the lateral view of the acetabulum can be a complementary method to identify malpositioned screws, and it helps increase the accuracy rate of inserting screws in the treatment of posterior wall fracture.

First experiences with the Airo mobile intraoperative CT scanner in acetabular surgery-An analysis of 10 cases

BACKGROUND

Being a proven method in trauma and spine surgery, intraoperative 3D imaging (CBCT) has intrinsic deficits in difficult anatomy and with artifacts because of metal implants. The purpose of this study was to evaluate the use of intraoperative computed tomography (iCT) in acetabular surgery.

METHODS

Ten cases of acetabular fractures that were operated with intraoperative use of the mobile CT scanner Brainlab Airo were analyzed. Data were compared with a historical group of 17 patients.

RESULTS

Additional fluoroscopy time was 24.2 seconds (6-91), which was significantly lower than in the control group where it was 211.4 seconds (77-446; P < 0.000). Operation time did not differ significantly (iCT group 196.8 min [122-288], control group 240.8 min [71-411], P = 0.234).

CONCLUSION

iCT provides images of a reliable high quality and assessability. Radiation exposure to the staff is reduced while surgery time is not altered significantly. Quality of intraoperative imaging and thus patient care can substantially improve patient outcome.

Establishment of fluoroscopy views and standardized procedure of percutaneous magic screw insertion for acetabulum fractures

Background

To place the magic screw more simply, we established a set of reproducible fluoroscopic views and a standardized procedure of magic screw insertion.

Materials and methods

This study on the magic screw tunnel uses a three-dimensional reconstruction model and a skeleton projection. The 3D model of the pelvis was made to be transparent and it was rotated to the place where the ischial spine was just sheltered by the posterior wall of the acetabulum. The angles of this view projection were recorded in the transverse plane and coronal plane. Six cadaveric pelvises (three males, three female) were used to validate the proper projection angle of the C-arm fluoroscopy. The skeleton specimens were all positioned latericumbent on a radiolucent table.

Result

In all pelvis 3D models, all magic cylinders with a 7.3 mm diameter were successfully inserted along the bone structure tunnel in 30 3D pelvic models. The average angle of the transverse view rotated by the C-arm fluoroscopy was 162° in males and 157° in females, the angle of the coronal plane was 22° in males and 24° in females. The average distance between the front wheel of the C-arm machine and the middle axial line of the radiolucent bed was 43 cm in males and 43 cm in females. In skeleton pelvis research, all the screws were safely inserted using this method.

Conclusion

The magic screw technique could be a good choice for the treatment of acetabular fractures, especially quadrilateral plate fractures. If the proper fluoroscopy view technique is used properly, the magic screw can be inserted rapidly and safely.

Intraoperative assessment of reduction and implant placement in acetabular fractures-limitations of 3D-imaging compared to computed tomography

Background

In acetabular fractures, the assessment of reduction and implant placement has limitations in conventional 2D intraoperative imaging. 3D imaging offers the opportunity to acquire CT-like images and thus to improve the results. However, clinical experience shows that even 3D imaging has limitations, especially regarding artifacts when implants are placed. The purpose of this study was to assess the difference between intraoperative 3D imaging and postoperative CT regarding reduction and implant placement.

Methods

Twenty consecutive cases of acetabular fractures were selected with a complete set of intraoperative 3D imaging and postoperative CT data. The largest detectable step and the largest detectable gap were measured in all three standard planes. These values were compared between the 3D data sets and CT data sets. Additionally, possible correlations between the possible confounders age and BMI and the difference between 3D and CT values were tested.

Results

The mean difference of largest visible step between the 3D imaging and CT scan was 2.0 ± 1.8 mm (0.0–5.8, p = 0.02) in the axial, 1.3 ± 1.4 mm (0.0–3.7, p = 0.15) in the sagittal and 1.9 ± 2.4 mm (0.0–7.4, p = 0.22) in the coronal views. The mean difference of largest visible gap between the 3D imaging and CT scan was 3.1 ± 3.6 mm (0.0–14.1, p = 0.03) in the axial, 4.6 ± 2.7 mm (1.2–8.7, p = 0.001) in the sagittal and 3.5 ± 4.0 mm (0.0–15.4, p = 0.06) in the coronal views. A positive correlation between the age and the difference in gap measurements in the sagittal view was shown (rho = 0.556, p = 0.011).

Conclusions

Intraoperative 3D imaging is a valuable adjunct in assessing reduction and implant placement in acetabular fractures but has limitations due to artifacts caused by implant material. This can lead to missed malreduction and impairment of clinical outcome, so postoperative CT should be considered in these cases.

Comparison of Isocentric C-Arm 3-Dimensional Navigation and Conventional Fluoroscopy for Percutaneous Retrograde Screwing for Anterior Column Fracture of Acetabulum: An Observational Study

Percutaneous screw insertion for minimally displaced or reducible acetabular fracture using x-ray fluoroscopy and computer-assisted navigation system has been advocated by some authors. The purpose of this study was to compare intraoperative conditions and clinical results between isocentric C-arm 3-dimensional (Iso-C 3D) fluoroscopy and conventional fluoroscopy for percutaneous retrograde screwing of acetabular anterior column fracture.A prospective cohort study was conducted. A total of 22 patients were assigned to 2 different groups: 10 patients in the Iso-C 3D navigation group and 12 patients in the conventional group. The operative time, fluoroscopic time, time of screw insertion, blood loss, and accuracy were analyzed between the 2 groups.There were significant differences in operative time, screw insertion time, fluoroscopy time, and mean blood loss between the 2 groups. Totally 2 of 12 (16.7%) screws were misplaced in the conventional fluoroscopy group, and all 10 screws were in safe zones in the navigation group. Percutaneous screw fixation using the Iso-C 3D computer-assisted navigation system significantly reduced the intraoperative fluoroscopy time and blood loss in percutaneous screwing for acetabular anterior column fracture.The Iso-C 3D computer-assisted navigation system provided a reliable and effective method for percutaneous screw insertion in acetabular anterior column fractures compared to conventional fluoroscopy.

Open reduction and internal fixation aided by intraoperative 3-dimensional imaging improved the articular reduction in 72 displaced acetabular fractures

BACKGROUND AND PURPOSE

During acetabular fracture surgery, the acetabular roof is difficult to visualize with 2-dimensional fluoroscopic views. We assessed whether intraoperative 3-dimensional (3D) imaging can aid the surgeon to achieve better articular reduction and improve implant fixation.

PATIENTS AND METHODS

We operated on 72 acetabular fractures using intraoperative 3D imaging and compared the operative results, duration of surgery, and complications with those for 42 consecutive acetabular fracture operations conducted using conventional fluoroscopic imaging. Postoperative reduction was evaluated on reconstructed coronal and sagittal images of the acetabulum.

RESULTS

The fracture severity and patient characteristics were similar in the 2 groups. In the 3D group, 46 of 72 patients (0.6) had a perfect result after open reduction and internal fixation, and in the control group, 17 of 42 (0.4) had a perfect result. The mean difference in postoperative articular incongruity was 0.5 mm (95% CI: 0.4-0.7). In 29 of 72 operations, the intraoperative 3D scans led to intraoperative correction of the reduction and an improved result. The duration of surgery and infection rate were similar in the 2 groups.

INTERPRETATION

Intraoperative 3D imaging, which is not time-consuming, allowed the surgeon to correct malreductions and screw placement in 29 of 72 operations, leading to better articular reduction and more precise screw placement than in operations where conventional fluoroscopic imaging was used to control the reduction.

Efficacy of Routine Postoperative CT Scan After Open Reduction and Internal Fixation of the Acetabulum

OBJECTIVES

The purpose of this study was to evaluate the efficacy of routine postoperative computed tomography (CT) scan after open reduction and internal fixation of acetabular fractures.

DESIGN

Retrospective review of prospectively collected acetabulum fracture database.

SETTING

Level I trauma center.

PATIENTS/PARTICIPANTS

A total of 606 consecutive patients underwent surgical fixation of 612 acetabular fractures. All patients were evaluated with intraoperative fluoroscopy in addition to 3 standard plain radiographs (AP pelvis and two 45 degrees oblique Judet views). Reduction and fixation were believed to be adequate and definitive before exiting the operative suite based on these imaging modalities.

INTERVENTION

Axial postoperative CT scan of the pelvis was obtained in 563 of the patients (93%) after 569 operative cases.

MAIN OUTCOME MEASUREMENTS

Revision acetabular surgery based on routine postoperative CT scan findings.

RESULTS

There were no significant differences between index and revision surgery groups regarding age, gender, body mass index, fracture pattern, mechanism of injury, or surgical approach (P > 0.05). Evaluation of 563 postoperative CT scans of the pelvis resulted in revision acetabular surgery for 2.5% of patients (n = 14). There were 6 (1.1%) cases of intraarticular hardware not recognized on the intraoperative fluoroscopy or pelvic radiographs. Four patients (0.7%) had residual intraarticular osteochondral fragments deemed too large to leave in the hip joint. There were 3 cases (0.5%) of unacceptable malreduction, and 1 case (0.2%) of both malreduction and an intraarticular osteochondral fragment.

CONCLUSIONS

A small percentage of patients (2.5%) will benefit from a routine CT scan after acetabular fracture fixation.

LEVEL OF EVIDENCE

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

Sex-specific differences of the infraacetabular corridor: a biomorphometric CT-based analysis on a database of 523 pelves

BACKGROUND

An infraacetabular screw path facilitates the closure of a periacetabular fixation frame to increase the plate fixation strength in acetabular fractures up to 50%. Knowledge of the variance in corridor sizes and axes has substantial surgical relevance for safe screw placement.

QUESTIONS/PURPOSES

(1) What proportion of healthy pelvis specimens have an infraacetabular corridor that is 5 mm or larger in diameter? (2) Does a universal corridor axis and specific screw entry point exist? (3) Are there sex-specific differences in the infraacetabular corridor size or axis and are these correlated with anthropometric parameters like age, body weight and height, or the acetabular diameter?

METHODS

A template pelvis with a mean shape from 523 segmented pelvis specimens was generated using a CT-based advanced image analyzing system. Each individual pelvis was registered to the template using a free-form registration algorithm. Feasible surface regions for the entry and exit points of the infraacetabular corridor were marked on the template and automatically mapped to the individual samples to perform a measurement of the maximum sizes and axes of the infraacetabular corridor on each specimen. A minimum corridor diameter of at least 5 mm was defined as a cutoff for placing a 3.5-mm cortical screw in clinical settings.

RESULTS

In 484 of 523 pelves (93%), an infraacetabular corridor with a diameter of at least 5 mm was found. Using the mean axis angulations (54.8° [95% confidence interval {CI}, 0.6] from anterocranial to posterocaudal in relation to the anterior pelvic plane and 1.5° [95% CI, 0.4] from anteromedial to posterolateral in relation to the sagittal midline plane), a sufficient osseous corridor was present in 64% of pelves. Allowing adjustment of the three-dimensional axis by another 5° included an additional 25% of pelves. All corridor parameters were different between females and males (corridor diameter, 6.9 [95% CI, 0.2] versus 7.7 [95% CI, 0.2] mm; p<0.001; corridor length, 96.2 [95% CI, 0.7] versus 106.4 [95% CI, 0.6] mm; p<0.001; anterior pelvic plane angle, 54.0° [95% CI, 0.9] versus 55.3° [95% CI, 0.8]; p<0.01; sagittal midline plane angle, 4.3° [95% CI, 0.6] versus -0.3° [95% CI, 0.5]; p<0.001).

CONCLUSION

This study provided reference values for placement of a 3.5-mm cortical screw in the infraacetabular osseous corridor in 90% of female and 94% of male pelves. Based on the sex-related differences in corridor axes, the mean screw trajectory is approximately parallel to the sagittal midline plane in males but has to be tilted from medial to lateral in females. Considering the narrow corridor diameters, we suggest an individual preoperative CT scan analysis for fine adjustments in each patient.

Percutaneous screw placement in acetabular posterior column surgery: gender differences in implant positioning

Percutaneous reduction and periarticular screw implantation techniques have been successfully introduced in acetabular surgery. Image guided navigation techniques might be beneficial in increasing accuracy. However, a thorough understanding of standard values is needed to oversee pitfalls. This cadaver study was designed to identify reliable angulation values for screw implantation in the posterior acetabular column and to provide knowledge of the bony thickness for the periarticular corridor. Gender differences were specifically addressed. 27 embalmed cadaveric hemipelvic specimens (13 male, 14 female) were used. After soft-tissue removal posterior column acetabular screw placement was conducted by one experienced orthopaedic trauma surgeon under visibility. Radiographic verification of ideal screw placement was followed by radiographic assessment in three standard views and angulation values were assessed. Through bony dissection the maximal periarticular canal width was assessed. Various angulation values with regard to anatomical landmarks could be determined in the anteroposterior radiograph, as well as in the iliac oblique and the obturator oblique view. Gender differences were significant for all reference points with the pubic rami involved. The minimal canal width was 1.1cm in female and 1.6 cm in male specimen. The findings provide standard values for safe passages in percutaneous posterior column acetabular surgery. Gender differences have to be taken in consideration when planning the drill corridor. By adherence to standard values, screw placement can be performed safely.

Comparative study of W-shaped angular plate and reconstruction plate in treating posterior wall fractures of the acetabulum

Objective

This study aims to assess the medium-term results of the reconstruction of posterior wall fractures using a W-shaped acetabular angular plate (WAAP) compared to those fixed using a reconstruction plate.

Methods

Between July 2006 and March 2009, we performed a retrospective study, which collected data for any patient treated for a posterior acetabular wall fracture. At the time of treatment, patients were either treated using a WAAP or a pelvic reconstruction plate. The intraoperative fluoroscopic images for both groups were compared. The quality of reduction and radiological grading were assessed according to the criteria developed by Matta. The clinical assessment was based on a modified Merle d’Aubigne and Postel scoring.

Results

53 patients met the inclusion criteria and were followed up for an average of 38 months. 25 patients were treated with a WAAP (study group), and 28 patients were treated with a pelvic reconstruction plate (control group). The intraoperative fluoroscopic images of the study group confirmed extra-articular screw placement in all cases. In the control group, intra-articular screw placement was observed intraoperatively in 5 patients (17.86%), and the definitive location of the periarticular hardware could not be determined in 4 patients (14.29%) during the operation. The differences between the two groups were statistically significant (p = 0.002). In contrast, the quality of fracture reduction, clinical outcomes, and radiological grading in the study group were not significantly different from those of the control group (p>0.05). The radiographic grade was strongly associated with the clinical outcomes in both the study and control groups (p<0.05).

Conclusion

Reconstruction of posterior wall fractures of the acetabulum using a WAAP can help avoid screw penetration of the hip joint, provide a stable fixation of the posterior wall, and ensure good clinical outcomes.

Usefulness of intraoperative three-dimensional imaging in fracture surgery: a prospective study

BACKGROUND

Since its introduction, intraoperative three-dimensional (3D) imaging has enabled the analysis of articular fractures and implant positions during fracture surgery. The purpose of this study was to evaluate the usefulness of intraoperative 3D imaging in locating anatomic structures, correcting errors, and preventing revision surgery.

METHODS

Between March 2010 and November 2012, intraoperative 3D imaging was used during surgery for 109 fractures in 101 patients. Fluoroscopy was performed with the Iso-C3D (Siemens, Erlangen, Germany). We recorded the number of intraoperative revisions for adjustment of fracture reduction and correction of implant position for these fractures.

RESULTS

Cases comprised intra-articular fractures (55%), disruptions of the posterior pelvic ring (33%), and syndesmotic injury (12%). The intraoperative revision rate was 9.2% (10/109). When considered by fracture site, the revision rate was highest for syndesmotic injury (23.1%), followed by iliosacral fixation (8.3%) and intra-articular fractures (6.6 %). We changed the implant position in six cases, corrected the articular reduction in one case, and revised the malreduction of syndesmosis in three cases. No postoperative infection occurred in any of these cases.

CONCLUSIONS

Intraoperative 3D imaging is useful for correcting errors and may prevent a second operation. Three-dimensional imaging may be especially helpful in intra-articular fractures, iliosacral screw fixation, and syndesmotic injury.

The management of acetabular malunion with traumatic arthritis by total hip arthroplasty

Objective: To explore the treatment strategies and clinical effect of the acetabular malunion with traumatic arthritis by total hip arthroplasty.

Methodology: A retrospective analysis was conducted on 47 cases of acetabular malunion with traumatic arthritis from June 2000 to December 2009. All the patients underwent total hip arthroplasty with bone grafting or titanium cage for bone defect of the acetabulum. Harris hip scoring system was used for evaluating the functional recovery of the hip joint.

Results: Thirty three cases had an average of 47 months follow-up. No prosthesis was loosened and the function of hip joint was improved obviously with the Harris hip scores improving from 43.5 to 87.6. However, there were one case of sciatic nerve injury and four cases of heterotopic ossification postoperatively.

Conclusion: Total hip arthroplasty might be an effective treatment of acetabular malunion with traumatic arthritis. Proper evaluation and reasonable reconstruction of acetabular defect as well as reasonable selection of prosthesis are essential to obtain an excellent outcome.

Computer-assisted percutaneous scaphoid fixation: concepts and evolution

Background The treatment for undisplaced scaphoid waist fractures has evolved from conventional cast immobilization to percutaneous screw insertion. Percutaneous fixation reduces some of the risks of open surgery, but can be technically demanding and carries the risk of radiation exposure. Recently, computer-assisted percutaneous scaphoid fixation (CAPSF) has been gaining interest. Materials and Methods Conventional percutaneous scaphoid fixation is performed under fluoroscopic guidance and involves insertion of a guide wire along the length of the scaphoid to facilitate placement of a cannulated screw. Adapting computer-assisted techniques for scaphoid fixation poses several unique challenges including patient tracking and registration. Results To date, five groups have successfully implemented systems for CAPSF. These systems have implemented wrist immobilization strategies to resolve the issue of patient tracking and have developed unique guidance techniques incorporating 2D fluoroscope, cone-beam CT, and ultrasound, to circumvent patient-based registration. Conclusions Computer-aided percutaneous pinning of scaphoid waist fractures can significantly reduce radiation exposure and has the potential to improve the accuracy of this procedure. This article reviews the rationale for, and the evolution of, CAPSF and describes the key principles of computer-assisted technology.

Intraoperative syndesmotic reduction: three-dimensional versus standard fluoroscopic imaging

BACKGROUND

The quality of reduction of the syndesmosis is an important factor in the outcome of ankle fractures associated with a syndesmotic injury. The purpose of this study was to directly compare the accuracy of syndesmotic reductions obtained using intraoperative standard fluoroscopic techniques against reductions obtained using three-dimensional imaging of the Iso-C3D fluoroscope.

METHODS

We prospectively reviewed imaging studies of patients who were diagnosed as having preoperative or intraoperative evidence of syndesmotic diastasis (on the basis of the fluoroscopic Cotton test and/or a manual external rotation stress test) who underwent syndesmotic fixation at one of two level-I trauma centers. Center A used intraoperative computed tomography (CT) imaging to assess reduction (≤2 mm), while Center B assessed reduction under standard fluoroscopic imaging. Postoperative alignment was assessed in a standardized manner, measuring anterior fibular distance, posterior fibular distance, and the anterior translation distance. Measurements were taken on the injured side and the uninjured side and compared between the groups on postoperative axial CT scans.

RESULTS

A total of thirty-six patients in both centers met our inclusion criteria and were included in the data analysis. Despite utilization of the Iso-C(3D), a high rate of malreductions was noted in both groups. Anterior translation distance malreductions occurred in 31% of the sixteen patients in Center A and 25% of the twenty patients in Center B (p = 0.72). The number of anterior fibular distance malreductions was similar, with a rate of 38% in Center A and 30% in Center B (p = 0.73). A significant difference among the centers (p = 0.03) was noted, however, when the posterior fibular distance data was analyzed, with 6% being malreduced by >2 mm in Center A and 40% in Center B.

CONCLUSIONS

The results of our study support previous investigations that have cited high rates of syndesmotic malreductions and demonstrate that the addition of advanced intraoperative imaging techniques does not help to reduce the rate of malreductions in this cohort.

Screw placement for acetabular fractures: which navigation modality (2-dimensional vs. 3-dimensional) should be used? An experimental study

OBJECTIVES

Screw navigation techniques with different image guidance [2-dimensional (2D) vs. 3-dimensional (3D) fluoroscopy] were evaluated for acetabular fracture surgery.

METHODS

Two-dimensional and 3D navigation images were analyzed for visualization of different osseous corridors: supra-acetabular, anterior column, posterior column, and infra-acetabular. Forty guide wires per group were placed in synthetic pelvis with a prefabricated soft tissue envelope (10 per group) using a 2D or 3D fluoroscopic navigation procedure. Duration of the single steps for each procedure and of cumulative fluoroscopy time was measured. The accuracy of guide wire placement was evaluated visually and in 3D cone-beam scans.

RESULTS

The overall procedure time per pelvis was significantly reduced in the 3D group compared with the 2D group [mean ± standard error (SE) (minutes): 50.11 ± 1.38 vs. 63.42 ± 2.32; P < 0.0001]. A trend to reduction in image acquisition time [mean ± SE (minutes): 12.37 ± 1.34 vs. 15.43 ± 1.03; P = not significant] and significant increase in the cumulative fluoroscopy time [mean ± SE (seconds): 64 ± 9 vs. 13 ± 1.3; P < 0.0001) was measured in the 3D compared with the 2D group, caused by the 3D scan. Intra-articular misplacements were not observed in both the groups, but an increased accuracy could be achieved using the 3D image-based navigation procedure (perfect placement: 37 vs. 29; secure placement: 2 vs. 7; misplacement: 1 vs. 4).

CONCLUSIONS

Both navigation procedures securely prevent an intra-articular penetration during drilling, but the 3D image-based navigation procedure increases the overall accuracy compared with the 2D image-based navigation technique (misplacement rates of 2.5% vs. 10%). Especially, in very narrow corridors (as the infra-acetabular screw path), the use of 3D navigation should be preferred.

Radiation exposure during 3D fluoroscopy of the knee: an experimental study

PURPOSE

To measure the radiation exposure at the knee and surrounding area during the use of 3D fluoroscopy.

METHODS

An experimental study was conducted by using a human cadaveric knee as a focus point for the 3D fluoroscope. An isocentric C-arm fluoroscope machine was applied on the lateral side of the knee. The radiation dosage at the focus point and surrounding area was measured. The mean radiation exposure in each location was compared between low- and high-resolution scanning.

RESULTS

The mean radiation sustained at the focus point was 44.0 ± 5.6 μSv and 20.0 ± 1.0 μSv in high- and low-resolution scanning, respectively. Radiation exposure on the opposite side of the C-arm machine was found to be higher than that on the other locations with the same distance from the focus point. In low-resolution scanning, radiation could not be detected beyond 75 cm from the focus point at the proximal, distal and same side of the machine. Radiation could be measured at a distance of up to 1.25 m on the opposite side of the machine. In high-resolution scanning, radiation could be measured at a distance of up to 1 m at the proximal, distal and same side of the C-arm, but up to 1.5 m on the opposite side.

CONCLUSION

Radiation exposure during 3D fluoroscopy of the knee decreases with increasing distance from the focus point. A higher number of scans in the high-resolution mode causes greater radiation exposure. In isocentric 3D fluoroscopy of the knee, a safe zone is located at least 1.5 m away from the focus point.

Percutaneous screw fixation for the acetabular fracture with quadrilateral plate involved by three-dimensional fluoroscopy navigation: surgical technique

BACKGROUND

The percutaneous three-dimensional (3D)-fluoroscopic-navigated screw directing to the quadrilateral plate was attempted.

MATERIALS AND METHODS

Five patients with acetabular fractures were treated by 3D navigated percutaneous screw. The quadrilateral plate was involved in all the patients. The Arcadis 3D (ARCADIS Orbic 3D(®); Siemens AG Healthcare Sector, Erlangen, Germany) and computer navigation system (stryker navigation system) were employed, screwing trajectory was attempted to anchor the quadrilateral plate perpendicularly to the fracture line and close to the joint cartilage as much as possible. Parameters including fracture gap closure (P1), distance to the joint cartilage (P2), angulations between the screw and the fracture line (P3), were measured with the software installed on the machine of Arcadis 3D.

RESULT

Seven screws were inserted with the use of 3D fluoroscopic navigation. The quadrilateral plate was hold by percutaneous screws. The closure of fracture gap was achieved in 3 patients by 2-3mm. The nearest distance from the screw to the joint cartilage was ranged from <1mm to 6mm. The angulations between the screw and the fracture line was 80-90° in three patients, it was 60° and 65° respectively on the rest two patients. All patients felt pain free 1week after the operation. No complication was noted postoperatively.

CONCLUSION

The surgical technique of percutaneous screwing for the acetabular fracture with three-dimensional fluoroscopy-based navigation was demonstrated.

Volume slicing of cone-beam computed tomography images for navigation of percutaneous scaphoid fixation

PURPOSE

Percutaneous scaphoid fixation (PSF) is growing in popularity as a treatment option for non-displaced fractures. Success of this procedure demands high-precision screw placement, which can be difficult to achieve with standard 2D imaging. This study aimed to develop and test a system for computer-assisted navigation using volume slicing of 3D cone-beam computed tomography (CBCT).

METHODS

The navigated technique involved a distinctive workflow in which a 3D CBCT imager was calibrated preoperatively, circumventing the need for intraoperative patient-based registration. Intraoperatively, a 3D CBCT image was acquired for both preoperative planning and direct navigation using volume-rendered slices. An in vitro study was conducted to compare the navigated approach to two conventional fluoroscopic methods for volar PSF. The surgical goal was to insert a guide wire to maximize both length and central placement.

RESULTS

There was no significant difference in the mean central placement of guide wire, although the variance in central placement was significantly lower using VS navigation (P < 0.01). The lengths of the drill paths were significantly longer for the VS-navigated group compared with one 2D group (P < 0.1). Each navigated trial required only one drilling attempt and resulted in less radiation exposure than conventional C-arm (P < 0.01).

CONCLUSIONS

Volume-sliced navigation achieved a more repeatable and reliable central pin placement, with fewer drilling attempts than conventional 2D techniques. Volume-sliced navigation had a higher number of drill paths within the optimal zone maximizing both length of the path and depth from the surface.

Minimally invasive fluoro-navigation screw fixation for the treatment of pelvic ring injuries

Intensive use of intraoperative fluoroscopy is mandatory to achieve good accuracy and avoid neural or vascular injury and may prolong surgical time and increase exposure-related hazards. New methods of percutaneous treatment in conjunction with innovative fluoroscopy-based computerized navigation have evolved in an attempt to overcome the existing difficulties. This report described our experience in applying fluoroscopic surgical navigation technique and evaluated its clinical application to pelvic ring injuries, including its feasibility, merits and limitations. Twenty-two patients with pelvic ring injuries were treated with percutaneous pubic ramus screw and sacroiliac screw techniques under the guidance of a fluoroscopy-based navigation system. A total of forty-four screws were inserted, including twenty-seven pubic ramus screws and seventeen sacroiliac screws. The average operation time and the average fluoroscopy time per screw were 23.6 minutes and 22.2 seconds respectively. Compared to the final position of the screw, the average deviated distance of wire tip was 2.8 mm and the average trajectory difference was 2.6°. A ventral cortex perforation of the sacrum was found in one sacroiliac screw without any clinical symptoms. No superficial or deep infection occurred. No patient sustained recognized neurologic, vascular, or urologic injury as a result of percutaneous screw fixation of pubic ramus fractures, sacroiliac disruptions, or sacral fractures. Our results showed that fluoroscopy-based navigation technique for the pelvic ring injuries could become a safe and effective alterative method for the treatment of pelvic ring injuries in some selected patients.

Intraoperative three-dimensional fluoroscopy assessment of iliosacral screws and lumbopelvic implants stabilizing fractures of the os sacrum

INTRODUCTION

Percutaneous iliosacral screw fixation of unstable sacrum fractures has gained popularity since its introduction in the 1990s. The combination with lumbopelvic implants allows the application even in situations of higher instability. Both manual and navigated screw insertion in the sacrum and vertebra bodies shows unchanged relevant malpositions. The current standard to control the screw position is postoperative computed tomography. The study presents the results of assessment of these implants by intraoperative three-dimensional fluoroscopy.

METHODS

From January 2008 through March 2009, 14 patients had stabilization of the dorsal pelvic ring with iliosacral screws alone or in combination with lumbopelvic implants. Intraoperative 3D fluoroscopy was performed to evaluate the position of the implants stabilizing the posterior pelvic ring.

RESULTS

Fourteen iliosacral screws and eight pedicle screws were depicted. In all patients, we were able to adequately evaluate the placement of iliosacral screws, lumbar pedicle screws and iliacal screws. As a consequence of intraoperative 3D scan a lumbar pedicle screw was corrected. The entire scanning procedure required 5 min. The time for analyzing the 3D scan took 3 min.

CONCLUSIONS

Intraoperative 3D fluoroscopy is a valuable tool for intraoperative assessment of iliosacral screws and lumbopelvic implants. The technique should help us to detect intraoperative malplacement of the screws more reliably than conventional fluoroscopy and allows an immediate correction of malplaced implants. Therefore, a postoperative computed tomography to control the position of implants is dispensable.

The study of plate-screw fixation in the posterior wall of acetabulum using computed tomography images

OBJECTIVE

The article aims to delineate the width of posterior column, the thickness of posterior wall, and safe angles for screw placement in the posterior wall to avoid intraarticular screw penetration.

METHODS

The computed tomography (CT) images of 32 cadaveric adult bony hemipelvic specimens were initially obtained for the purpose of the study. Each specimen was sectioned at 1-cm intervals, and each plane of the crosssection was perpendicular to the surface of posterior column. By analyzing the CT images postprocessed with multiplanar reconstruction, the width of posterior column, the thickness of posterior wall, and the modified safe angle for screw placement in the posterior wall were measured and recorded. To validate the data obtained from the cadaveric model, this method was applied on 30 adult volunteers. The corresponding data were recorded and compared with those acquired from the cadaveric bony hemipelvis. In efforts to approve the usefulness of this method in practice, we have performed screw insertions in another 10 acetabular specimens and two operative cases by using the data from analyzing the CT images.

RESULTS

The width of posterior column, the thickness of posterior wall, and the safe angles for screw insertion in the posterior wall were measured and recorded in both specimens and volunteers. Comparison of the corresponding data was made between specimens and volunteers, and no significant difference was found in the same gender and side (p > 0.05). The corresponding width of posterior column, thickness of posterior wall, and safe angles for screw placement was found to be statistically different between males and females in both specimens and volunteers (p < 0.05). In specimens group, the safe angles for the entry points 0.5, 1.0, 1.5, 2.0, 2.5, and 3.0 cm medial to the lateral acetabular brim were 49.23 degrees +/- 11.54 degrees, 42.48 degrees +/- 8.97 degrees, 29.53 degrees +/- 7.86 degrees, 23.68 degrees +/- 6.20 degrees, 18.42 degrees +/- 5.41 degrees and 15.91 degrees +/- 4.37 degrees in males and the corresponding angles for the entry points 0.5, 1.0, 1.5, 2.0, and 2.5 cm medial to the lateral acetabular brim were 45.02 degrees +/- 8.82 degree, 35.98 degrees +/- 7.60 degrees, 23.77 degrees +/- 6.29 degrees, 19.96 degrees +/- 4.36 degrees, and 14.68 degrees +/- 3.48 degrees in females, respectively. CT images of 10 acetabular specimens and two cases with posterior wall fractures show all screws were inserted into the posterior wall without penetration into the joint space.

CONCLUSIONS

The oblique multiplanar reconstruction images perpendicular to the surface of posterior column were selected to describe the safe angle for screw insertion into posterior wall, which can provide consistent results in both specimens and volunteers. The method can be applied in practice both on acetabular specimens and operative cases and is helpful to make individual perioperative planning for safer fixation of posterior wall fracture.

Percutaneous screw fixation of acetabular fractures with 2D fluoroscopy-based computerized navigation

INTRODUCTION

The treatment of displaced acetabular fractures with formal open reduction and internal fixation has gained general acceptance. However, extensile exposure can lead to complications. Two-dimensional fluoroscopy-based computerized navigation for placement of percutaneous screw across non-displaced acetabular fractures has attracted interest by making use of stored patient-specific imaging data to provide real-time guidance in multiple image planes during implant placement. The purpose of the present study was to document early treatment results and complications associated with this new technique and evaluate its clinical application to displaced acetabular fractures amenable to closed or limited open reduction.

MATERIALS AND METHODS

Eighteen adult patients with 12 non-displaced and 8 displaced acetabular fractures were treated with percutaneous screw fixation under the guidance of a fluoroscopy-based navigation system. There were 14 men and four women with a mean age of 42.1 years (range 19-54 years). According to the AO and Orthopaedic Trauma Association Classification, there were nine 62-A3, five 62-B1, three 62-B2, and three 62-B3. The mean follow-up was 21 months (range 12-28 months). The mean time from injury to surgery was 4 days (range 2-7 days).

RESULTS

A total of 30 acetabular screws were inserted, including 21 anterior column screws and 9 posterior column screws. The average operation time was 24.6 min (range 16-47 min) from the image acquisition to wound closure. The average fluoroscopic time was 28.4 s (range 11-58 s). Compared to the final position of the screw, the average deviated distance of wire tip was 2.5 mm (range 1.1-3.6 mm) and the average trajectory difference was 2.45 degrees (range 1.5 degrees -4.6 degrees ). Maximal gap displacement averaged 10 mm (range 2-22 mm) preoperatively and 3 mm (range 0-5 mm) postoperatively; while maximal step displacement averaged 4 mm (range 1-10 mm) preoperatively and 2 mm (range 0-4 mm) postoperatively. One patient sustained a transient femoral nerve palsy and resolved 2 months after the operation. No superficial or deep infection occurred. Using the rating system of D'Aubigne and Postel, 13 patients had excellent results, 4 patients had good results, and 1 patient had a fair result.

CONCLUSION

Percutaneous screw fixation of acetabular fractures with 2D fluoroscopy-based navigation could be applied not only to non-displaced fractures but also to displaced fractures amenable to closed or limited open reduction.

Fluoroscopic templating technique for precision arthroscopic rim trimming

Arthroscopic rim trimming for femoroacetabular impingement can be technically challenging to perform with precision. Intraoperative assessment of the extent of acetabular rim resection is very important. Over-resection can lead to hip instability and even iatrogenic dislocation. Under-resection may leave residual impingement. A novel imaging technique is presented that is simple, practical, and readily available. The technique involves matching the fluoroscopic C-arm image intensifier to the operative pelvis while under the desired amount of hip distraction so that a horizontal anteroposterior hip image appears on the viewing monitor. An erasable marking pen is used to draw the desired area of planned acetabular rim resection directly on the viewing monitor screen. Intermittent fluoroscopic images with the raised stationary C-arm device allow assessment of superior (lateral) and anterior rim resection. The surgeon "wipes away" the drawn template with the radiopaque metallic bur until the all-important medial template border is reached, indicating that the actual rim resection matches that intended in a controlled and precise manner.

Utility of intraoperative three-dimensional imaging at the hip and knee joints with and without navigation

Intraoperative three-dimensional imaging in orthopaedic trauma care has achieved greater importance over the last few years in some specialized hospital centers. For various types of peripheral-extremity trauma, clinical studies have confirmed, on the basis of three-dimensional information, an intraoperative revision rate ranging from 7% to 19%. Three-dimensional C-arm imaging may be used to achieve adequate intraoperative information about the quality of fracture reduction, residual steps, and correct implant placement, and this technique has been described for use in both the hip joint (for acetabular fractures, isolated femoral head [Pipkin-type] fractures, three-dimensional navigated sacroiliac screw or acetabular column screw placements, and, less frequently, for navigated drilling of tumors or osteochondral lesions) and the knee joint (for tibial plateau fractures, complex distal femoral condylar fractures, and navigated targeting of osteochondral lesions in combination with the use of preoperative magnetic resonance imaging scans). Major limitations of this technology include increased intraoperative time requirements, limited image quality compared with that of computed tomographic scans, cost, specific positioning techniques, and the need for radiolucent operating-room tables. Although prospective studies have yet to be conducted, the ways in which the surgeon will benefit from the use of intraoperative three-dimensional imaging are apparent, but indications for combined three-dimensional C-arm navigated procedures at the hip and knee joint are still limited. Future directions may include the use of digital flat-panel detectors and even robotic-controlled C-arm motion.