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

Vertical Versus Pfannenstiel Incision-Modified Stoppa Approach in the Treatment of Acetabular Fractures

OBJECTIVES

The aims of this study were to compare the patient and fracture characteristics, radiological, functional, and quality of life outcomes; the need for a lateral window approach and requirement of total hip arthroplasty; and complications in patients with simple and complex acetabular fractures who underwent a modified Stoppa approach through vertical and Pfannenstiel incisions.

METHODS

DESIGN

This was a retrospective comparison study.

SETTING

Level 1 trauma center.

PATIENT SELECTION CRITERIA

Patients with acetabular fractures (A-O-/-O-T-A type 62A-B-C) treated with vertical (group V) or Pfannenstiel (group P) incision-modified Stoppa approach between 2010 and 2020 were included.

OUTCOME MEASURES AND COMPARISONS

Patient characteristics, radiological evaluations (reduction quality and posttraumatic osteoarthritis), patient functional outcomes [12-item Short-Form Survey (SF-12) physical component score, SF-12 mental component score, Harris Hip Score, and Merle d'Aubigné-Postel], approach modifications and stratification by fracture type and complications were compared between those treated with vertical or Pfannenstiel incisions.

RESULTS

One hundred four patients (mean age of 38.5 ± 14.3 years) were included. There was no significant difference between the Pfannenstiel or vertical groups regarding patient and fracture characteristics (P = 0.137), postoperative reduction quality (P = 0.130), or the mean functional and quality of life outcome scores at the last follow-up (P = 0.483 for the Harris Hip Score, P = 0.717 for the Merle d'Aubigné-Postel score, P = 0.682 for the SF-12 physical component score, and P = 0.781 for the SF-12 mental component score). In group P, significantly more patients needed additional lateral incisions (40.8% vs. 10.9%; P 0.001) and total hip replacement procedures (12.2% vs. 1.8%; P = 0.049). The total, early, and late complication rates were significantly higher in group P (P 0.001, P = 0.034, and P = 0.049, respectively).

CONCLUSIONS

Pfannenstiel incision was associated with higher complication rates than vertical incision in acetabular fractures treated through a modified Stoppa approach. Fracture complexity is associated with the need for a lateral window approach and total hip arthroplasty, as well as a worse functional and radiological outcome regardless of incision type. However, it was not associated with the development of intraoperative or postoperative complications.

LEVEL OF EVIDENCE

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

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.

Standard versus low-dose computed tomography for assessment of acetabular fracture reduction using novel step and gap measurement technique

PURPOSE

Quality of reduction is of paramount importance after acetabular fracture and is best assessed on computed tomography (CT). A recently proposed measurement technique for assessment of step and gap displacement is reproducible but has not been validated. The purpose of this study is to validate a well-established measurement technique against known displacements and to determine if it can be used with low dose CT.

METHODS

Posterior wall acetabular fractures were created in 8 cadaveric hips and fixed at known step and gap displacements. CT was performed at multiple radiation doses for each hip. Four surgeons measured step and gap displacement for each hip at all doses, and the measurements were compared to known values.

RESULTS

There were no significant differences in measurements across surgeons, and all measurements were found to have positive agreement. Measurement error < 1.5 mm was present in 58% of gap measurements and 46% of step measurements. Only for step measurements at a dose of 120 kVp did we observe a statistically significant measurement error. There was a significant difference in step measurements made by those with greater and those with fewer years in practice.

CONCLUSION

Our study suggests this technique is valid and accurate across all doses. This is important as it may reduce the amount of radiation exposure for patients with acetabular fractures.

Effect of O-arm on reduction quality and functional recovery of acetabular dome impaction fractures: a retrospective clinical study

BACKGROUND

Acetabular dome impaction fractures (ADIF) are difficult to reduce and have a high failure rate. Consistency between the acetabulum and the femoral head is usually assessed using intraoperative X-ray fluoroscopy to evaluate the quality of fracture reduction. This study examines the effects of intraoperative mobile 2D/3DX imaging system (O-arm) on the reduction quality and functional recovery of ADIF.

METHODS

We retrospectively analysed the data of 48 patients with ADIF treated at Honghui Hospital between October 2018 and October 2021.The patients were divided into the X-ray and O-arm groups. The residual step-off and gap displacements in the acetabular dome region were measured, and fracture reduction quality was evaluated. Hip function was evaluated using the modified Merle d'Aubigné and Postel scoring systems.

RESULTS

There were no significant intergroup differences in the preoperative general data (p > 0.05). The mean residual average step displacement in the acetabular dome region was 3.48 ± 2.43 mm and 1.61 ± 1.16 mm (p < 0.05), while the mean gap displacement was 6.72 ± 3.69 mm and 3.83 ± 1.67 mm (p < 0.05) in the X-ray and the O-arm groups, respectively. In the X-ray group, according to the fracture reduction criteria described by Verbeek and Moed et al., one case was excellent, 13 cases were good, 11 cases were poor; 56% were excellent or good. In the O-arm group, seven cases were excellent, 12 cases were good, and four cases were poor; overall in this group, 82.6% were excellent or good (p < 0.05). A total of 46 patients achieved fracture healing at the last follow-up. In the X-ray group, according to the modified Merle d'Aubigné and Postel function score, three cases were excellent,12 cases were good, six cases were middle, three cases were poor; 62.5% were excellent or good, In the O-arm group, 15 cases were excellent, four cases were good, two cases were middle, one case was poor; 86.4% were excellent or good (p < 0.05).

CONCLUSIONS

The application of O-arm in ADIF can improve fracture reduction quality and functional recovery.

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.

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.

Predicting the Poor Clinical and Radiographic Outcomes after the Anatomical Reduction and Internal Fixation of Posterior Wall Acetabular Fractures: A Retrospective Analysis

Anatomical reduction is the fundamental principle of hip function restoration after posterior acetabular wall fractures (PWFs). Some patients exhibit poor outcomes despite anatomical reduction, and the prognostic factors leading to poor outcomes remain elusive. This study aimed to investigate the clinical and radiographic outcomes in patients with PWFs who had undergone anatomical reduction and internal fixation and to identify the predictors that impair clinical and radiologic outcomes. The clinical records of 60 patients with elementary PWFs who had undergone anatomical reduction and internal fixation between January 2005 and July 2015 were reviewed retrospectively. The Harris hip score (HHS) and modified Merle d’Aubigné clinical hip scores (MMAS) were used to evaluate the clinical outcome. Preoperative and final follow-up radiographs were cross checked to identify poor radiographic outcomes that included the presence of advanced osteoarthritis and osteonecrosis, as well as the need for conversion to total hip arthroplasty. Acetabular dome comminution was assessed from computerized tomography, and the outcomes were further evaluated according to the involvement of fragment comminution. The fracture comminution and age were negatively correlated with functional outcomes (correlation coefficients were −0.41 and −0.39 in HHS and MMAS, respectively) and were significantly related to the severity of osteoarthritis and osteonecrosis as well as the need for total hip arthroplasty. Regarding the radiographic factors, significantly worse post-operative HHS and MMAS were found in the fracture comminution group. In the subanalysis of the status of fracture comminution, patients with fragment comminution involving the acetabular dome had significantly lower functional scores than those with other fracture patterns. In conclusion, age, fracture comminution, and dome comminution were the prognostic indicators of advanced osteoarthritis and poor functional scores after the anatomical reduction and internal fixation of PWFs. We emphasized the relevance of acetabular dome comminution as an important contributing factor to clinical and radiographic outcomes.

The Reliability of Postoperative Radiographic Matta Grading for Quality of Reduction of Acetabular Fractures

OBJECTIVES

To assess the reliability of the postoperative radiographic Matta grading for quality of reduction of acetabular fractures.

DESIGN

An inter-reliability and intrareliability study.

SETTING

Level I trauma center.

PARTICIPANTS

15 independent observers of different levels of experience who evaluated 115 sets of postoperative acetabulum radiographs in 35 consecutive patients with displaced acetabular fractures between January 2017 and January 2019.

MAIN OUTCOME MEASUREMENTS

To assess the interobserver and intraobserver reliability of Matta radiographic grading for postoperative quality of reduction of acetabular fractures.

RESULTS

The overall interobserver agreement was excellent among all groups with an average absolute intraclass correlation coefficient (ICC) of 0.91 (95% CI 0.93-0.97). When stratifying the agreement based on experience, the orthopaedic trauma fellow subgroup had the highest rate with an ICC of 0.92. The overall intraobserver agreement was good with an ICC of 0.81 (95% CI 0.74-0.85).

CONCLUSION

The Matta radiographic grading was a reliable tool for the evaluation of quality of reduction after surgical fixation of acetabular fractures with excellent interobserver and good intraobserver reliabilities among different levels of observers.

Excessively long interfragmentary screws for posterior wall acetabular fractures can predict intra-articular penetration

BACKGROUND

The fixation of posterior wall acetabular fractures often utilizes interfragmentary screws with varying length. Intricate pelvic anatomy and overhanging greater trochanter make obtaining proper screw trajectory difficult. A large measurement may represent aberrant trajectory and breach of the articular surface. This study aims to identify a preferred maximum screw length that avoids intra-articular penetration.

HYPOTHESIS

We hypothesized that a screw measured 40 millimeters or longer has a high likelihood of being intra-articular.

PATIENTS AND METHODS

A retrospective review included CT scans of 151 consecutive patients collected at a level-1 trauma center was analyzed by two observers. On axial imaging, a straight line was measured at the largest extraarticular portion of the posterior wall simulating ideal screw placement. Another line was measured tangent to the articular surface simulating longest possible extraarticular screw. Measurements were taken at 2-millimeter increments.

RESULTS

The intra-class correlation coefficient between both observers was excellent (0.75-1.00) for most recorded values. The maximum mean length for straight line measured (m=32.18mm, SD=3.74) which was smaller than the mean length for tangent line (m=38.44, SD=4.29). Exploratory multivariate logistic regression analyses demonstrated increased height, age, and acetabular version were associated with larger measurements greater than 40mm (p<0.05).

DISCUSSION

This study demonstrates that most acetabular posterior walls cannot accommodate a 40 millimeter lag screw. If the measured drill hole is greater than this length, then careful reconsideration of the screw trajectory is warranted to ensure the screw is not intra-articular. Older and taller patients may be able to accommodate longer screws.

LEVEL OF EVIDENCE

III.

Periarticular screws: what's in and what's out of the joint?

Periarticular hardware placement can be challenging and a source of angst for orthopaedic surgeons due to fear of penetrating the articular surface and causing undue harm to the joint. In recent years, many surgeons have turned to computed tomography (CT) and other intraoperative or postoperative modalities to determine whether hardware is truly extraarticular in areas of complex anatomy. Yet, these adjuncts are expensive, time consuming, and often unnecessary given the advancement in understanding of intraoperative fluoroscopy. We present a review article with the goal of empowering surgeons to leave the operating room, with fluoroscopy alone, assured that all hardware is beneath the articular surface that is being worked on. By understanding a simple concept, surgeons can extrapolate the information in this article to any joint and bony surface in the body. While targeted at both residents and surgeons who may not have completed a trauma fellowship, this review can benefit all orthopaedic surgeons alike.

The accuracy of gap and step-off measurements in acetabular fracture treatment

The assessment of gaps and steps in acetabular fractures is challenging. Data from various imaging techniques to enable accurate quantification of acetabular fracture displacement are limited. The aim of this study was to assess the accuracy of pelvic radiographs, intraoperative fluoroscopy, and computed tomography (CT) in detecting gaps and step-offs in acetabular fractures. Sixty patients, surgically treated for acetabular fractures, were included. Five observers (5400 measurements) measured the gaps and step-offs on radiographs and CT scans. Intraoperative fluoroscopy images were reassessed for the presence of gaps and/or step-offs. Preoperatively, 25% of the gaps and 40% of the step-offs were undetected on radiographs compared to CT. Postoperatively, 52% of the gaps and 80% of the step-offs were missed on radiographs compared to CT. Radiograph analysis led to a significantly smaller gap and step-off compared to the CT measurements, an underestimation by a factor of two. Approximately 70% of the residual gaps and step-offs was not detected using intraoperative fluoroscopy. Gaps and step-offs that exceed the critical cut-off indicating worse prognosis often remained undetected on radiographs compared to CT scans. Less-experienced observers tend to overestimate gaps and step-offs compared to the more-experienced observers. In acetabular fracture treatment, gaps and step-offs were often undetected and underestimated on radiographs and intraoperative fluoroscopy in comparison with CT scans. This means that CT is superior to radiographs in detecting acetabular fracture displacement, which is clinically relevant for patient counselling regarding treatment decisions and prognosis.

Accuracy of Posterior Wall Acetabular Fracture Lag Screw Placement: Correlation Between Intraoperative Fluoroscopy and Postoperative Computer Tomography

OBJECTIVE

Compare intraoperative "on end" fluoroscopy lag screw position to postoperative computer tomography.

DESIGN

Retrospective review.

CLINICAL SETTING

Level 1 trauma center.

PATIENTS

One hundred sixteen patients sustaining operative acetabular fractures with posterior wall components.

INTERVENTION

Posterior wall lag screws placed using "on end" fluoroscopic imaging.

MAIN OUTCOME MEASUREMENTS

The primary outcome was determining correlation between lag screw position, in relation to the acetabular articular margin, using intraoperative fluoroscopy and postoperative computer tomography. Analysis was performed based on location around the acetabulum, including posterior (P), superoposterior (SP), and superior (S) regions, and screws 0-5, 5-10, and >10 mm from the joint.

RESULTS

Two hundred forty-four lag screws were identified as follows: 51.6% in the P group, 25.4% in SP, and 23.0% in the S group with excellent correlation noted in all groups. For screws pooled based on fluoroscopic distance from the joint, 28.3% were 0-5 mm, 52.9% 5.01-10 mm, and 18.4% >10 mm. Correlation coefficients were 0.60 for 0-5 mm and 0.68 for both groups >5 mm. Subdividing screws based on anatomic region and fluoroscopic location found increasing correlation as screws moved further from the joint in the P region. In the SP group, excellent correlation was noted for screws 0-5 mm with decreasing correlation further from the joint. Within the S group, correlation for screws 0-5 mm did not reach significance, but good correlation was noted for screws >5 mm. Overall incidence of intraarticular screws was 1.2%.

CONCLUSIONS

Intraoperative axial fluoroscopy for posterior wall lag screw placement correlates closely with postoperative computer tomography allowing for reliable posterior wall lag screw placement in all regions around the acetabulum. Care should be taken while placing lag screws within 5 mm of the articular surface, particularly within the posterior region.

What Are the Interobserver and Intraobserver Variability of Gap and Stepoff Measurements in Acetabular Fractures?

BACKGROUND

Gap and stepoff values in the treatment of acetabular fractures are correlated with clinical outcomes. However, the interobserver and intraobserver variability of gap and stepoff measurements for all imaging modalities in the preoperative, intraoperative, and postoperative phase of treatment is unknown. Recently, a standardized CT-based measurement method was introduced, which provided the opportunity to assess the level of variability.

QUESTIONS/PURPOSES

(1) In patients with acetabular fractures, what is the interobserver variability in the measurement of the fracture gaps and articular stepoffs determined by each observer to be the maximum one in the weightbearing dome, as measured on pre- and postoperative pelvic radiographs, intraoperative fluoroscopy, and pre- and postoperative CT scans? (2) What is the intraobserver variability in these measurements?

METHODS

Sixty patients with a complete subset of pre-, intra- and postoperative high-quality images (CT slices of < 2 mm), representing a variety of fracture types with small and large gaps and/or stepoffs, were included. A total of 196 patients with nonoperative treatment (n = 117), inadequate available imaging (n = 60), skeletal immaturity (n = 16), bilateral fractures (n = 2) or a primary THA (n = 1) were excluded. The maximum gap and stepoff values in the weightbearing dome were digitally measured on pelvic radiographs and CT images by five independent observers. Observers were free to decide which gap and/or stepoff they considered the maximum and then measure these before and after surgery. The observers were two trauma surgeons with more than 5 years of experience in pelvic surgery, two trauma surgeons with less than 5 years of experience in pelvic surgery, and one surgical resident. Additionally, the final intraoperative fluoroscopy images were assessed for the presence of a gap or stepoff in the weightbearing dome. All observers used the same standardized measurement technique and each observer measured the first five patients together with the responsible researcher. For 10 randomly selected patients, all measurements were repeated by all observers, at least 2 weeks after the initial measurements. The intraclass correlation coefficient (ICC) for pelvic radiographs and CT images and the kappa value for intraoperative fluoroscopy measurements were calculated to determine the inter- and intraobserver variability. Interobserver variability was defined as the difference in the measurements between observers. Intraobserver variability was defined as the difference in repeated measurements by the same observer.

RESULTS

Preoperatively, the interobserver ICC was 0.4 (gap and stepoff) on radiographs and 0.4 (gap) and 0.3 (stepoff) on CT images. The observers agreed on the indication for surgery in 40% (gap) and 30% (stepoff) on pelvic radiographs. For CT scans the observers agreed in 95% (gap) and 70% (stepoff) of images. Postoperatively, the interobserver ICC was 0.4 (gap) and 0.2 (stepoff) on radiographs. The observers agreed on whether the reduction was acceptable or not in 60% (gap) and 40% (stepoff). On CT images the ICC was 0.3 (gap) and 0.4 (stepoff). The observers agreed on whether the reduction was acceptable in 35% (gap) and 38% (stepoff). The preoperative intraobserver ICC was 0.6 (gap and stepoff) on pelvic radiographs and 0.4 (gap) and 0.6 (stepoff) for CT scans. Postoperatively, the intraobserver ICC was 0.7 (gap) and 0.1 (stepoff) on pelvic radiographs. On CT the intraobserver ICC was 0.5 (gap) and 0.3 (stepoff). There was no agreement between the observers on the presence of a gap or stepoff on intraoperative fluoroscopy images (kappa -0.1 to 0.2).

CONCLUSIONS

We found an insufficient interobserver and intraobserver agreement on measuring gaps and stepoffs for supporting clinical decisions in acetabular fracture surgery. If observers cannot agree on the size of the gap and stepoff, it will be challenging to decide when to perform surgery and study the results of acetabular fracture surgery.

LEVEL OF EVIDENCE

Level III, diagnostic study.

Surgical management of acetabular fractures - A contemporary literature review

Surgical management of acetabular fractures is now commonplace for almost all displaced or unstable fractures. Over the last 20 years however, the patient population has aged, and there have been significant changes to safety in motor vehicles and the work-place, and people's activity types and levels have changed. The surgical specialty has also developed with time, and as a result acetabular fracture surgery today is different to 20 years ago. We have repeated a meta-analysis originally published by Giannoudis et al in 2005, to evaluate contemporary aspects of acetabular fracture patients, injury mechanisms, management, complications and functional outcomes. This paper compares data from the last 15 years to that published in 2005. We have analysed a total of 8389 fractures from 8372 patients. The mean patient age has risen from 38.6 to 45.2. A change in injury mechanisms is seen, with road traffic accidents now accounting for 66.5% of cases (previously over 80%), and a rise in the number of fractures caused by falls from 10.7 to 25.8%. There has been a marked change in the fracture types seen, with a significant rise in anterior column-based fractures (Anterior column and Anterior column posterior hemi-transverse), whilst all other fracture patterns have fallen over time. Surgery is now taking place earlier, the Kocher-Langenbeck and Ilioinguinal approaches remain the major surgical approaches used, but the Anterior Intra-Pelvic approach has become relatively common. The most significant change in complications is a substantial drop in iatrogenic nerve damage, particularly to the sciatic nerve. Post-traumatic osteoarthritis remains the major complication of this injury, with 16.9% of cases developing Matta grade III/IV changes by 44 months in this review. Heterotopic ossification also remains a common problem. Despite these changes over time, functional outcomes after acetabular fracture appear to remain similar, although there is still a lack of good quality data on medium and longer-term functional outcomes from which to assess this.

Standard Versus Low-Dose Computed Tomography for Assessment of Acetabular Fracture Reduction

OBJECTIVE

First, to assess the impact of varying computed tomography (CT) radiation dose on surgeon assessment of postfixation acetabular fracture reduction and malpositioned implants. Second, to quantify the accuracy of CT assessments compared with the experimentally set displacement in cadaver specimens. We hypothesized that a CT dose would not affect the assessments and that CT assessments would show a high concordance with known displacement.

METHODS

We created posterior wall acetabular fractures in 8 fresh-frozen cadaver hips and reduced them with varying combinations of step and gap displacement. The insertion of an intra-articular screw was randomized. Each specimen had a CT with standard (120 kV), intermediate (100 kV), and low-dose (80 kV) protocols, with and without metal artifact reduction postprocessing. Reviewers quantified gap and step displacement, overall reduction, quality of the scan, and identified intra-articular implants.

RESULTS

There were no significant differences between the CT dose protocols for assessment of gap, step, overall displacement, or the presence of intra-articular screws. Reviewers correctly categorized displacement as anatomic (0-1 mm), imperfect (2-3 mm), or poor (>3 mm) in 27.5%-57.5% of specimens. When the anatomic and imperfect categories were condensed into a single category, these scores improved to 52.5%-82.5%. Intra-articular screws were correctly identified in 56.3% of cases. Interobserver reliability was poor or moderate for all items. Reviewers rated the quality of most scans as "sufficient" (60.0%-72.5%); reviewers more frequently rated the low-dose CT as "inferior" (30.0%) and the standard dose CT as "excellent" (25%).

CONCLUSION

A CT dose did not affect assessment of displacement, intra-articular screw penetration, or subjective rating of scan quality in the setting of a fixed posterior wall fracture.

Solutions for failed osteosynthesis of the acetabulum

Osteosynthesis of the acetabulum is complex and requires very careful planning and preoperative preparation. The goal is to achieve anatomical reduction without steps or gaps in the articular surface. If it has not been possible to achieve an optimal reconstruction, one has to consider whether it makes sense to carry out reosteosynthesis or revise the fixation. The risk of infection, heterotopic ossification, avascular necrosis of the femur and cartilage damage is much higher than with the primary procedure. Often, especially in older patients, it may make more sense to achieve fracture union and to implant a total hip prosthesis in due course. In younger patients, every attempt should be made to achieve optimum anatomical reduction and this may mean consideration of reosteosynthesis after careful planning and counselling of the patient. If reosteosynthesis is considered adequate imaging including a postoperative CT is essential as part of the planning. This article looks at the possible solutions for failed osteosynthesis of the acetabulum.

Are Routine Postoperative Computer Tomography Scans Warranted for All Patients After Operative Fixation of Pelvic Ring Injuries?

OBJECTIVE

To evaluate the efficacy of routine postoperative computed topography (CT) scan after percutaneous fixation of unstable pelvic ring injuries.

DESIGN

Retrospective chart review.

SETTING

Level I Trauma Center.

PATIENTS/PARTICIPANTS

A total of 362 consecutive patients underwent operative fixation of unstable pelvic ring injuries during the study period.

INTERVENTION

Postoperative CT scan of the pelvis was obtained in 331 (91%) of the 362 patients treated operatively for unstable pelvic ring injuries.

MAIN OUTCOME MEASUREMENTS

Revision surgery based on routine postoperative CT scan.

RESULTS

Two patients (0.55%) returned to the operating room on the basis of postoperative CT scans due to malpositioned implants. There were no significant differences of age, sex, body mass index, Injury Severity Score, mechanism of injury, smoking status, or diabetes status between those who did and did not undergo revision surgery. A dysmorphic pelvis was identified in 154 (47%) patients. Both patients undergoing revision surgery were determined to have a dysmorphic pelvis while no patients with normal pelvic anatomy returned to the operating room based on postoperative CT (2/154, 1.3% vs. 0/177, 0%, P = 0.22).

CONCLUSIONS

Although there remains a role for postoperative CT scans in the appropriately selected patient, in the hands of experienced orthopaedic traumatologists, patients with adequate intraoperative fluoroscopy and a nondysmorphic pelvis may not require routine postoperative three-dimensional imaging.

LEVEL OF EVIDENCE

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

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.

Imaging Acetabular Fractures

Acetabular fractures are encountered by radiologists in a wide spectrum of practice settings. The radiologist's value in the acute and long-term management of acetabular fractures is augmented by familiarity with systematic computed tomography-based algorithms that streamline and simplify Judet-Letournel fracture typing, together with an appreciation of the role of imaging in initial triage, operative decision making, postoperative assessment, prognostication, and evaluation of complications. The steep increase in incidence of acetabular fractures in the elderly over the past several decades places special emphasis on familiarity with geriatric fracture patterns.

Does Routine Postoperative Computerized Tomography After Acetabular Fracture Fixation Affect Management?

INTRODUCTION AND AIMS

The use of routine postoperative computerized tomography (CT) scan after acetabular fracture reconstruction remains controversial. CT scan may provide more accurate detail regarding metalwork position, retained intra-articular fragments, and quality of reduction but does expose the patient to additional radiation dosage and incurs increased cost. The aim of this study was to evaluate a protocol of routine postoperative CT scan for all acetabular fractures after surgical fixation and assess the effect this has on patient management.

PATIENTS AND METHODS

The perioperative fluoroscopic images and postoperative plain radiographs of 122 patients who underwent surgical stabilization of a displaced acetabular fracture were reviewed and categorized into 3 groups: (1) safe, when there was no suspicion of metalwork malposition or intra-articular fragments; (2) inconclusive, when it was not possible to exclude malposition; or (3) definite malposition or intra-articular penetration of implants. The findings were compared with postoperative CT scans. The quality of reduction of the acetabular fracture was graded on plain radiographs using the Matta criteria and compared with the CT scan using a standardized technique.

RESULTS

Fractures that were categorized as safe on plain radiographs were confirmed to have no metalwork malposition on CT scan in 94% of the cases, with the other 6% having insignificant findings that did not require revision surgery. When plain radiographs were inconclusive (n = 17), 4 patients had metalwork malposition documented on CT scan and 2 of these required revision surgery. There was an increased risk of implant malposition with use of spring plates for posterior wall stabilization. There was significant variation between the quality of reduction when assessed with plain radiographs as compared with CT scans (P < 0.001). In 42% of the patients who were thought to have anatomic reduction on plain radiographic assessment, the reduction was either imperfect or poor based on CT assessment.

CONCLUSIONS

CT scans were more accurate than plain radiographs in detecting metalwork malposition and in assessing quality of reduction of the acetabular fracture. The use of postoperative CT scans may be restricted to a group of fractures that have inconclusive or definite malpositioning of implants on perioperative or postoperative radiographs, especially with use of spring pates or to those patients in whom quality of reduction needs more accurate assessment for quality assurance or prognostic reasons.

LEVEL OF EVIDENCE

Level IV; Diagnostic -Investigating a diagnostic test.

Computed tomography versus plain radiography assessment of acetabular fracture reduction is more predictive for native hip survivorship

INTRODUCTION

Computed tomography (CT) is more accurate than plain pelvic radiography (PXR) for evaluating acetabular fracture reduction. As yet unknown is whether CT-based assessment is more predictive for clinical outcome. We determined the independent association between reduction quality according to both methods and native hip survivorship following acetabular fracture fixation.

MATERIALS AND METHODS

Retrospectively, 220 acetabular fracture patients were reviewed. Reductions on PXR were graded as adequate or inadequate (0-1 mm or > 1 mm displacement) (Matta's criteria). For CT-based assessment, adequate reductions were defined as < 1 mm step and < 5 mm gap, and inadequate reductions as ≥ 1 mm step and/or ≥ 5 mm gap displacement. Predictive values and Kaplan-Meier hip survivorship curves were compared and risk factors for conversion to total hip arthroplasty (THA) were identified.

RESULTS

Mean follow-up was 8.9 years (SD 5.6, range 0.5-23.3 years), and 52 patients converted to THA (24%). Adequate reductions according to CT versus PXR assessment were associated with higher predictive values for native hip survivorship (92% vs. 82%; p = 0.043). Inadequate reductions were equally predictive for conversion to THA (33% for CT and 30% for PXR; p = 0.623). For both methods, survivorship curves of adequate versus inadequate reductions were significantly different (p = 0.030 for PXR, p < 0.001 for CT). Only age ≥ 50 years (p < 0.001) and inadequate reductions as assessed on CT (p = 0.038) were found to be independent risk factors for conversion to THA. Reduction quality as assessed on PXR was not found to be independently predictive for this outcome (p = 0.585).

CONCLUSION

Native hip survivorship is better predicted based on postoperative CT imaging as compared to PXR assessment. Predicting need for THA in patients with inadequate reductions based on both assessment methods remains challenging. While both PXR and CT-based methods are associated with hip survivorship, only an inadequate reduction according to CT assessment was an independent risk factor for conversion to THA.

Assessing Postoperative Reduction After Acetabular Fracture Surgery: A Standardized Digital Computed Tomography-Based Method

Quality of reduction after acetabular fracture surgery is an important predictor of clinical outcome. Computed tomography (CT) is likely superior to plain pelvic radiography for assessment of postoperative reduction, but interobserver reliability may be limited in the absence of a widely adopted technique. We describe a standardized digital CT-based method for measuring residual (gap and step) displacement on CT after acetabular fracture surgery. In a selection of patients, we determined the interobserver reliability for measuring displacement and grading the quality of reduction on postoperative pelvic radiography and CT, with and without the use of this novel technique.

Patient-reported outcome measures after surgery for an acetabular fracture

Aims

The aim of this study was to record the incidence of post-traumatic osteoarthritis (OA), the need for total hip arthroplasty (THA), and patient-reported outcome measures (PROMS) after surgery for a fracture of the acetabulum, in our centre.

Patients and Methods

All patients who underwent surgery for an acetabular fracture between 2004 and 2014 were included. Patients completed the 36-Item Short Form Health Survey (SF-36) and the modified Harris Hip Score (mHHS) questionnaires. A retrospective chart and radiographic review was performed on all patients. CT scans were used to assess the classification of the fracture and the quality of reduction.

Results

A total of 220 patients were included, of which 55 (25%) developed post-traumatic OA and 33 (15%) underwent THA. A total of 164 patients completed both questionnaires. At a mean follow-up of six years (2 to 10), the mean SF-36 score for patients with a preserved hip joint was higher on role limitations due to physical health problems than for those with OA or those who underwent THA. In the dimension of bodily pain, patients with OA had a significantly better score than those who underwent THA. Patients with a preserved hip joint had a significantly better score on the function scale of the mHHS and a better total score than those with OA or who underwent THA.

Conclusion

Of the patients who were treated surgically for an acetabular fracture (with a mean follow-up of six years), 15% underwent THA at a mean of 2.75 years postoperatively. Patients with a THA had a worse functional outcome than those who retain their native hip joint. We recommend using PROMS and CT scans when reviewing these patients. Cite this article: Bone Joint J 2018;100-B:640-5.

Radiographic Evaluation of Acetabular Fractures: Review and Update on Methodology

Despite increased availability of modern imaging techniques, plain radiographs remain the initial step in the classification of acetabular fractures. The ability to interpret the injury configuration allows the surgeon to develop a thorough preoperative plan and to evaluate the quality of reduction and fixation intraoperatively. Proficiency in the mental conversion of a two-dimensional radiograph into a three-dimensional conceptual image is imperative. The widely used radiographic classification scheme developed by Judet and Letournel in the 1960s is both practical and simple. However, understanding the subtleties of the fracture pattern can be a challenge even for experienced surgeons. Current evaluation methods include CT and three-dimensional reconstructions in addition to plain radiographs. Our diagnostic algorithm uses three plain radiographs to classify the fracture into one of the 10 fracture patterns described by Judet and Letournel.

Routine Postoperative Computed Tomography Scans After Pelvic Fracture Fixation: A Necessity or a Luxury?

INTRODUCTION

There is no consensus regarding the postoperative radiology imaging protocol after pelvic fracture surgery. Some institutes routinely scan all patients after their surgery, others do not. The aim of this study was to assess the value of routine use of computed tomography (CT) scans after pelvic fracture surgery and to determine the sensitivity of conventional plain radiographs and intraoperative fluoroscopy in detecting metalwork malposition.

PATIENTS AND METHODS

The radiographs and clinical notes of patients undergoing pelvic fracture surgery in the period between January 2010 and December 2015 were reviewed. Patients were categorized into 2 main groups: group A-patients whose fixation entailed the use of a sacroiliac (SI) screws and group B-patients whose fixation did not require an SI screw. Furthermore, the patients were classified according to the position of metalwork in their postoperative plain radiographs and perioperative fluoroscopy into 3 groups: (1) Safe: When there was no suspicion of metalwork malposition. (2) Suspicious: When there was some suspicion of malposition but radiographs were inconclusive. (3) Definite: When plain imaging showed a definite malposition.

RESULTS

One hundred ninety-eight patients were included in this study (161 in group A and 37 in group B). In group A, 148 (92%) were classified as safe, 10 were suspicious (6%), and 3 (2%) showed definite malposition. Of the fractures that were believed to be safe on plain radiographs, 78% were confirmed to be safe on CT scans, whereas 22% showed malpositioned metalwork, and 7 patients (4%) required a revision surgery. Plain radiographs showed a sensitivity of 27% in detecting metalwork malposition and a specificity of 99%. Increasing the number of screws significantly increased the risk of malposition and reoperation (P = 0.006 and 0.002 respectively). The plain images of group B were all classified as safe. The CT scans detected 2 cases with long metalwork protruding into the soft tissues, none of which required a revision surgery.

CONCLUSION

Perioperative fluoroscopy and plain postoperative radiographs have a low sensitivity in detecting the metalwork malposition after pelvic fracture surgery. We recommend the use of routine postoperative CT scans in patients whose fixation entails the use of SI screws. In this series, routine scanning of patients who did not have SI screws added no significant clinical value.

LEVEL OF EVIDENCE

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

Postoperative CT Is Superior for Acetabular Fracture Reduction Assessment and Reliably Predicts Hip Survivorship

BACKGROUND

Postoperative pelvic radiographs are routinely used to assess acetabular fracture reduction. We compared radiographs and computed tomography (CT) with regard to their ability to detect residual fracture displacement. We also determined the association between the quality of reduction as assessed on CT and hip survivorship and identified risk factors for conversion to total hip arthroplasty (THA).

METHODS

Patients were included in the study who had undergone acetabular fracture fixation between 1992 and 2012, who were followed for ≥2 years (or until early THA), and for whom radiographs and a pelvic CT scan were available. Residual displacement was measured on postoperative radiographs and CT and graded according to Matta's criteria (0 to 1 mm indicating anatomic reduction; 2 to 3 mm, imperfect reduction; and >3 mm, poor reduction) by observers who were blinded to patient outcome. Kaplan-Meier survivorship curves were plotted and log-rank tests were used to assess statistical differences in survivorship curves between adequate (anatomic or imperfect) and inadequate reductions on CT. Cox proportional hazard regression analysis was used to identify risk factors for conversion to THA. Two hundred and eleven patients were included. At mean of 9.0 years (standard deviation [SD], 5.6; median, 7.9; range, 0.5 to 23.3 years) postoperatively, 161 patients (76%) had retained their native hip.

RESULTS

Compared with radiographs, CT showed worse reduction in 124 hips (59%), the same reduction in 79 (37%), and better reduction in 8 (4%). Of the 99 patients graded as having adequate reduction on CT, 10% underwent conversion to THA in comparison with 36% of those with inadequate reduction, and there was a significant difference between the survivorship curves (p < 0.001). Mean hip survivorship was shorter in patients ≥50 years of age (p < 0.001) and in those with an inadequate reduction on CT (p < 0.001). Independent risk factors for conversion to THA were age (hazard ratio [HR] = 4.46, 95% confidence interval [CI] = 2.07 to 9.62; p < 0.001), inadequate reduction (HR = 3.57, 95% CI = 1.71 to 7.45; p = 0.001), and posterior wall involvement (HR = 1.81, 95% CI = 1.00 to 3.26; p = 0.049). Sex, fracture type (elementary versus associated), and year of surgery did not influence hip survivorship.

CONCLUSIONS

CT is superior to radiographs for detecting residual displacement after acetabular fracture fixation. Hip survivorship is greater in patients with adequate (anatomic or imperfect) reduction on CT. Along with older age and posterior wall involvement, an inadequate reduction on CT is a risk factor for conversion to THA.

LEVEL OF EVIDENCE

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

Radiographic Measurement of Displacement in Acetabular Fractures: A Systematic Review of the Literature

OBJECTIVES

To report methods of measurement of radiographic displacement and radiographic outcomes in acetabular fractures described in the literature.

METHODS

A systematic review of the English literature was performed using EMBASE and Medline in August 2014. Inclusion criteria were studies of operatively treated acetabular fractures in adults with acute (<6 weeks) open reduction and internal fixation that reported radiographic outcomes. Exclusion criteria included case series with <10 patients, fractures managed >6 weeks from injury, acute total hip arthroplasty, periprosthetic fractures, time frame of radiographic outcomes not stated, missing radiographic outcome data, and non-English language articles. Basic information collected included journal, author, year published, number of fractures, and fracture types. Specific data collected included radiographic outcome data, method of measuring radiographic displacement, and methods of interpreting or categorizing radiographic outcomes.

DATA SYNTHESIS

The number of reproducible radiographic measurement techniques (2/64) and previously described radiographic interpretation methods (4) were recorded. One radiographic reduction grading criterion (Matta) was used nearly universally in articles that used previously described criteria. Overall, 70% of articles using this criteria documented anatomic reductions.

CONCLUSIONS

The current standard of measuring radiographic displacement in publications dealing with acetabulum fractures almost universally lacks basic description, making further scientific rigor, such as testing reproducibility, impossible. Further work is necessary to standardize radiographic measurement techniques, test their reproducibility, and qualify their validity or determine which measurements are important to clinical outcomes.

LEVEL OF EVIDENCE

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