Virtual registration of comminuted bone fracture and preoperative assessment of reconstructed bone model using the Procrustes algorithm based on CT dataset.

A research work was undergone in a virtual bone reduction process for reconstruction of the comminuted pelvic bone fracture using a CT scan dataset of patients. This includes segmentation, 3D model optimization and bone registration technique. The accuracy of the reconstructed bone model was validated using Finite Element Method. Analysed and applied various segmentation techniques to segregate the injured bone structure. The ICP (Iterative Closest Point), Procrustes algorithm and Canny edge detection algorithm were applied to understand the bone registration process for surgery in detail. The average RMS error, mean absolute distance, mean absolute deviation, and mean signed distance of the reconstructed bone model using proposed algorithms involving 10 patient datasets in a group were found to be 1.77, 1.48, 1.51 and -0.31 mm respectively. The calculated RMS error value proved minimal error in semi-automatic registration than other existing automatic registration techniques. Therefore, the proposed approach is suitable for virtual bone reduction for comminuted pelvic bone fracture. This method could also be implemented for various other bone fracture reconstruction requirements.

Assessment and management of pelvic fractures from high-energy trauma in adults.

Pelvic fractures caused by high-energy trauma such as falling from a height or road traffic collisions have a high mortality rate and patients are also at high risk of life-changing injuries. High-energy trauma to the pelvis is associated with major haemorrhage and injuries to the internal pelvic organs. Emergency nurses have a fundamental role in the initial assessment and management of patients, as well as in their ongoing care once the fracture has been stabilised and bleeding is controlled. This article describes the anatomy of the pelvis, discusses the initial assessment and management of patients who have sustained high-energy pelvic trauma, details the complications of pelvic fractures and explains patients' ongoing care in the emergency department.

Dual-Energy CT and Cinematic Rendering to Improve Assessment of Pelvic Fracture Instability.

Background Grading of pelvic fracture instability is challenging in patients with pelvic binders. Dual-energy CT (DECT) and cinematic rendering can provide ancillary information regarding osteoligamentous integrity, but the utility of these tools remains unknown. Purpose To assess the added diagnostic value of DECT and cinematic rendering, with respect to single-energy CT (SECT), for discriminating any instability and translational instability in patients with pelvic binders. Materials and Methods In this retrospective analysis, consecutive adult patients (age ≥18 years) were stabilized with pelvic binders and scanned in dual-energy mode using a 128-section CT scanner at one level I trauma center between August 2016 and January 2019. Young-Burgess grading by orthopedists served as the reference standard. Two radiologists performed blinded consensus grading with the Young-Burgess system in three reading sessions (session 1, SECT; session 2, SECT plus DECT; session 3, SECT plus DECT and cinematic rendering). Lateral compression (LC) type 1 (LC-1) and anteroposterior compression (APC) type 1 (APC-1) injuries were considered stable; LC type 2 and APC type 2, rotationally unstable; and LC type 3, APC type 3, and vertical shear, translationally unstable. Diagnostic performance for any instability and translational instability was compared between reading sessions using the McNemar and DeLong tests. Radiologist agreement with the orthopedic reference standard was calculated with the weighted κ statistic. Results Fifty-four patients (mean age, 41 years ± 16 [SD]; 41 men) were analyzed. Diagnostic performance was greater with SECT plus DECT and cinematic rendering compared with SECT alone for any instability, with an area under the receiver operating characteristic curve (AUC) of 0.67 for SECT alone and 0.82 for SECT plus DECT and cinematic rendering (P = .04); for translational instability, the AUCs were 0.80 for SECT alone and 0.95 for SECT plus DECT and cinematic rendering (P = .01). For any instability, corresponding sensitivities were 61% (22 of 36 patients) for SECT alone and 86% (31 of 36 patients) for SECT plus DECT and cinematic rendering (P < .001). The corresponding specificities were 72% (13 of 18 patients) and 78% (14 of 18 patients), respectively (P > .99). Agreement (κ value) between radiologists and orthopedist reference standard improved from 0.44 to 0.76 for SECT versus the combination of SECT, DECT, and cinematic rendering. Conclusion Combined use of single-energy CT, dual-energy CT, and cinematic rendering improved instability assessment over that with single-energy CT alone. © RSNA, 2022 Online supplemental material is available for this article.

An Innovative Technique for Intraoperative Radiological Assessment of Pelvic and Spine Fractures in Austere Environment.

INTRODUCTION: Managing pelvic and spine fractures in the austere environment can be challenging even for skilled orthopedic surgeons, largely due to the difficulty of radiological visualization of bone structures. We present a simple alternative to the metallic operating table by placing the patient on a spinal board that will allow for a better radiological assessment of these fractures. MATERIAL AND METHODS: A cross-sectional, descriptive, and retrospective study was carried out in the period between 2015 and 2020. The study population was all patients with pelvic o spine fractures, managed surgically using a spinal board in the Spanish Role 2 or in the Spanish Role 4. RESULTS: Seven patients underwent surgery in total using a spinal board, pelvic fracture being the the main diagnosis (n = 6; 85.71%). The distribution of surgical procedures was as follows: percutaneous pedicle screw fixation (one case), external fixation of the pelvis (two cases), percutaneous screw fixation of the pelvis (two cases), and open reduction and internal fixation of the pelvis (two cases). The mean duration of surgical interventions was 52 minutes, and a successful reduction and synthesis of the fracture was obtained in all the patients, with no complications reported. CONCLUSION: A spinal board can be a useful, simple, and effective device for the orthopedic surgeon in the deployed setting. The described technique is simple, fast, and efficient in getting a complete radiological assessment of complex regions such as the pelvis and the spine, facilitating the surgical management of these injuries.

Operative intervention of unstable paediatric pelvic fracture: radiological and functional assessment.

PURPOSE: The aim of the study was to add to the literature new data regarding the evaluation of surgical fixation of challenging unstable paediatric pelvic fractures, radiologically and clinically besides recording any complications through the follow-up period. METHODS: Prospective study was conducted at our hospital between 2012 and 2017 where 21 patients less than 16 years with unstable fracture pelvis were surgically fixed. The method of fixation varied between the external percutaneous fixation and internal fixation. The Infix system was used in for anterior ring fixation in some cases. Patients were evaluated radiologically and functionally using the functional independence measure questionnaire (FIM) and the modified Merle d'Aubigne and Postel (MDP) score. RESULTS: Twelve males and 9 females were fixed with mean age of 12.5 years. Motorcar accident was the main mode of trauma. Nine patients had fracture pelvis Tile's type B and 12 had Tile's type C injuries. All fractures united by 8 weeks. No patients suffered from pelvic asymmetry or leg length discrepancy at a mean follow-up of 2 years. The mean of FIM was 122.5 and the mean of MDP score was 16.2. CONCLUSION: Displaced unstable pelvic fractures in children need a systematic evaluation of the injury pattern. These serious fractures should be referred for anterior ± posterior ring stabilization. Promising clinical outcomes with surgical fixation can be reached with a low rate of complications. Further large-scale studies should be conducted for the calling literature.

Assessment of radiographic sacroiliitis in anteroposterior lumbar vs conventional pelvic radiographs in axial spondyloarthritis.

OBJECTIVE: The aim was to investigate the reliability and validity of radiographic sacroiliitis assessment in anteroposterior (AP) lumbar radiographs compared with conventional pelvic radiographs in patients with axial spondyloarthritis (axSpA). METHODS: Patients from the German Spondyloarthritis Inception Cohort were selected based on the availability of pelvic and AP lumbar radiographs with visible SI joints at baseline and year 2. Two readers scored the images independently in a random order according to the modified New York criteria. The sacroiliitis sum score was calculated as the mean of both readers. Patients were classified as radiographic (r-)axSpA if radiographic sacroiliitis of grade ≥2 bilaterally or grade ≥3 unilaterally was present in the opinion of both readers and as non-radiographic (nr-)axSpA otherwise. The reliability and validity of sacroiliitis assessment in AP lumbar radiographs was assessed using intraclass correlation coefficients (ICCs), absolute agreement and κ statistics. RESULTS: A total of 226 sets of radiographs were scored from 113 patients included in the study. The ICC for the sacroiliitis sum score was 0.91 at both baseline and year 2. A total of 62 (54.9%) and 55 (48.7%) patients were classified as r-axSpA at baseline and 65 (57.5%) and 60 (53.1%) patients at year 2 based on evaluation of pelvic and AP lumbar radiographs, respectively. The absolute agreement between the methods on the classification was 84.9 and 85.0% at baseline and year 2, respectively, with the κ of 0.70 at both time points. CONCLUSION: Radiographic sacroiliitis can be assessed in AP lumbar radiographs with a similar reliability to conventional pelvic radiographs.

Dose-Area Product-to-Effective Dose Conversion Coefficients for Pelvic Radiography Using a Monte Carlo Program.

OBJECTIVE. The purpose of this study was to determine dose-area product-to-effective dose (DAP/E) conversion coefficients for a five-view pelvic radiograph series. DAP/E conversion coefficients may be used for radiation dose optimization when designing institutional protocols for pelvic trauma evaluation. MATERIALS AND METHODS. We conducted a retrospective record review of 25 patients at a level 1 trauma center who had sustained pelvic fractures and required a five-view pelvic radiograph series during workup. E values given in International Commission on Radiological Protection Publication 103 were simulated with a PC-based Monte Carlo program in conjunction with anthropomorphic phantoms adjusted on the basis of patient height and weight. Inputs included tube voltage (in kV), tube filtration (in millimeters of aluminum), anode angle, x-ray beam collimation, geometric distances, and angle of projection for each radiograph in the series. An incident polychromatic x-ray spectrum was generated and matched to the corresponding DAP values of each radiograph, and regression analysis was performed for the DAP/E conversion coefficients. RESULTS.E was strongly correlated with DAP independent from body mass index, with a mean global DAP/E conversion coefficient of 0.0125 mSv/dGy · cm2 for all radiographs (R2 = 0.95). Mean DAP/E conversion coefficients were 0.0133, 0.0110, 0.0143, 0.0113, and 0.0101 mSv/dGy · cm2 for anteroposterior, inlet, outlet, Judet left, and Judet right views, respectively (all R2 ≥ 0.94). CONCLUSION. DAP/E conversion coefficients are provided for a five-view pelvic radiograph series to allow reliable estimation of E. Measurement of cumulative E may affirm protocol design changes for the management of pelvic trauma.

Assessment of Bone and Muscle Measurements by Peripheral Quantitative Computed Tomography in Geriatric Patients.

The loss of bone and muscle mass increases the risk of osteoporotic fractures. Dual energy X-ray absorptiometry (DXA) loses sensitivity in older age. The purpose of this study was to evaluate bone and muscle measurements of peripheral quantitative computed tomography (pQCT) in a geriatric cohort with osteoporosis. Bone mineral density and muscle area of 168 patients aged 65 years and older (76.3 ± 6.5) were measured with pQCT at distal forearm additionally to an osteoporosis assessment consisting of anamnesis, blood test and DXA of lumbar spine and hip. Prior fractures were categorized in minor and major osteoporotic fractures. Logistic regression was used to show the association of bone mineral density and muscle area with major fractures. 54.8% of the participants had at least one major fracture. Bone mineral density measured with pQCT and muscle area were significantly associated with these fractures (total and trabecular bone mineral density OR 2.243 and 2.195, p < 0.01; muscle area OR 2.378, p < 0.05), whereas DXA bone mineral density showed no significant association. These associations remained after adjustment for age, sex, BMI, physical activity and other factors. In all models for patients >75 years only muscle area was significantly associated (OR 5.354, p < 0.05) with major fractures. Measurement of bone mineral density and muscle area with pQCT seems to have advantage over DXA in fracture association in geriatric patients. Measuring muscle area also adds useful information to estimate the presence of osteosarcopenia.

Quantitative assessment of acetabular bone defects: A study of 50 computed tomography data sets.

OBJECTIVES: Acetabular bone defect quantification and classification is still challenging. The objectives of this study were to suggest and define parameters for the quantification of acetabular bone defects, to analyze 50 bone defects and to present the results and correlations between the defined parameters. METHODS: The analysis was based on CT-data of pelvises with acetabular bone defects and their reconstruction via a statistical shape model. Based on this data, bone volume loss and new bone formation were analyzed in four sectors (cranial roof, anterior column, posterior column, and medial wall). In addition, ovality of the acetabulum, lateral center-edge angle, implant migration, and presence of wall defects were analyzed and correlations between the different parameters were assessed. RESULTS: Bone volume loss was found in all sectors and was multidirectional in most cases. Highest relative bone volume loss was found in the medial wall with median and [25, 75]-percentile values of 72.8 [50.6, 95.0] %. Ovality, given as the length to width ratio of the acetabulum, was 1.3 [1.1, 1.4] with a maximum of 2.0, which indicated an oval shape of the defect acetabulum. Lateral center-edge angle was 30.4° [21.5°, 40.4°], which indicated a wide range of roof coverage in the defect acetabulum. Total implant migration was 25.3 [14.8, 32.7] mm, whereby cranial was the most common direction. 49/50 cases showed a wall defect in at least one sector. It was observed that implant migration in cranial direction was associated with relative bone volume loss in cranial roof (R = 0.74) and ovality (R = 0.67). CONCLUSION: Within this study, 50 pelvises with acetabular bone defects were successfully analyzed using six parameters. This could provide the basis for a novel classification concept which would represent a quantitative, objective, unambiguous, and reproducible classification approach for acetabular bone defects.

Impact of 3D surface scanning protocols on the Os coxae digital data: Implications for sex and age-at-death assessment.

The 3D imaging technologies have become of paramount importance for example in disciplines such as forensic anthropology and bioarchaeology, where they are being used more and more frequently. There are several new possibilities that they offer; for instance, the easier and faster sharing of data among institutions, the possibility of permanent documentation, or new opportunities of data analysis. An important requirement, however, is whether the data obtained from different scanning devices are comparable and whether the possible varying outputs could affect further analyses, such as the estimation of the biological profile. Therefore, we aimed to investigate two important questions: (1) whether 3D models acquired by two different scanning technologies (structured light and laser) are comparable and (2) whether the scanning equipment has an effect on the anthropological analyses, such as age-at-death estimation and sex assessment. 3D models of ossa coxa (n = 29) were acquired by laser (NextEngine) and structured light (HP 3D Structured Light Scanner PRO 2) scanners. The resulting 3D models from both scanners were subjected to age-at-death analyses (via the quantitative method of Stoyanova et al., 2017) and sex analyses (via Diagnose Sexuelle Probabiliste 2 of Bruzek et al., 2017). Furthermore, high quality scans of a small sample (n = 5) of pubic symphyseal surfaces with the RedLux Profiler device were acquired as reference surfaces to which the outputs from both scanners were compared. Small deviations between surfaces were more evident in more rugged surfaces (in areas of depression and protrusion). Even though small differences from the reference surfaces were found, they did not have a significant effect on the age and sex estimates. It never resulted in the opposite sex assignment, and no significant differences were observed between age estimates (with the exception of those with the TPS/BE model).

Assessment of hip fracture risk by cross-sectional strain-energy derived from image-based beam model.

BACKGROUND: Clinicians have been looking for a simple and effective biomechanical tool for the assessment of hip fracture risk. Dual-energy X-ray absorptiometry (DXA) is currently the primary bone imaging modality in clinic, and the engineering beam is the simplest model for a mechanical analysis. Therefore, we developed a DXA-based beam model for the above purpose. METHODS: A beam model of the proximal femur was constructed from the subject's hip DXA image and denoted DXA-beam. Femur stiffness was calculated at cross-sections of interest using areal bone-mineral-density profile. Impact force induced in a sideways fall was applied as a critical loading. Fracture risk index at a cross-section was defined as the ratio of strain-energy induced by the impact force to the allowable strain-energy. A clinic cohort was used to study the discriminability of DXA-beam, which was measured by the area under the curve and odds ratio, both with 95% confidential interval. FINDINGS: Fracture risk measured by DXA-beam model at the femoral neck [odds ratio 2.23, 95% confidence interval (1.83, 2.57)], inter-trochanter [2.49, (2.14, 3.25)] and sub-trochanter [2.82, (2.38, 3.51)] were strongly associated with hip fracture. The area under the curve by DXA-beam at the femoral neck [0.74, 95% confidence interval (0.70, 0.76)], inter-trochanter [0.77, (0.75, 0.82)] and sub-trochanter [0.76, (0.74, 0.81)] were higher than that by femoral neck bone mineral density [0.71, (0.65, 0.78)]. INTERPRETATION: The DXA-beam model is a simple and yet effective mechanical model. It had promising performance in discrimination of fracture cases from controls.

Is pelvis x-ray essential in stable trauma patients? Step towards lowering the treatment cost.

OBJECTIVE: To determine the diagnostic accuracy of clinical examination in detecting pelvic fractures in patients with blunt trauma.. METHODS: The cross-sectional prospective study was conducted at Aga Khan University Hospital, Karachi, from January to June 2015, and comprised alert, awake blunt-trauma patients. Pelvis examination findings were compared to routine pelvic X-rays. SPSS 19 was used for data analysis.. RESULTS: Of the 133 patients, 122 (92%) were males. Overall mean age was 37 ±14.2 years. There were 14 (10%) patients who were true positives with pelvic fracture diagnosis on both clinical examination and pelvic X-ray, while 14 (10%) were false negative on examination. Clinical examination missed 2 patients with evidence of fracture on X-ray and were considered false positive. Besides, 103 (77.4%) patients were true negative as both clinical exam and X-ray showed no evidence of fracture. CONCLUSION: Omitting pelvic X-ray in the recommended protocol can avoid unnecessary financial burden and reduce undesirable radiation exposure..

Assessment of pelvic tilt in anteroposterior radiographs by means of tilt ratios.

INTRODUCTION: In anteposterior (AP) radiographs, cup position in total hip arthroplasty and acetabular anatomy in hip-preserving surgery are highly influenced by pelvic tilt. The sagittal rotation of the anterior pelvic plane is an important measurement of pelvic tilt during hip surgery. Thus, correct evaluation of cup position and acetabular parameters requires the assessment of pelvic tilt in AP radiographs. METHODS: Changes in pelvic tilt inversely change the height of the lesser pelvis and the obturator foramen in AP radiographs. Tilt ratios were calculated by means of these two parameters in simulated radiographs for ten male and ten female pelvises in defined tilt positions. A tilt formula obtained by exponential regression analysis was evaluated by two blinded investigators by means of 14 simulated AP radiographs of the pelvis with pelvic tilts ranging from + 15° to - 15°. RESULTS: No differences were found between male and female tilt ratios for each 5° step of simulated pelvic tilt. Pelvic tilt and tilt ratios correlated exponentially. Using the tilt formula, the two blinded investigators were able to assess pelvic tilt with high conformity, a mean relative error of + 0.4° (SD ± 4.6°), and a mean absolute error of 3.9° (SD ± 2.3°). Neutral pelvic tilt is indicated by a tilt ratio of 0.5 when the height of the lesser pelvis is twice the height of the obturator foramen. CONCLUSION: The analysis and interpretation of cup position and acetabular parameters may be improved by our method for assessing pelvic tilt in AP radiographs.

Quantitative MDCT assessment of binder effects after pelvic ring disruptions using segmented pelvic haematoma volumes and multiplanar caliper measurements.

OBJECTIVE: To assess effects of pelvic binders for different instability grades using quantitative multidetector computed tomography (MDCT) parameters including segmented pelvic haematoma volumes and multiplanar caliper measurements. METHODS: CT examinations of 49 patients with binders and 49 controls performed from January 2008-June 2016, and matched 1:1 for Tile instability grade and Pennal/Young-Burgess force vector, were compared for differences in pubic symphysis and sacroiliac displacement using caliper measurements in three orthogonal planes. Pelvic haematoma volumes (ml) were derived using semi-automated seeded region-growing segmentation. Median caliper measurements and volumes were compared using the Mann-Whitney U test, and correlations assessed with Pearson's correlation coefficient. Relevant caliper measurement cutoffs were established using ROC analysis. RESULTS: Rotationally unstable (Tile B) patients with binders showed significant decreases in sacroiliac diastasis (2.7 mm vs. 4.5 mm; p=0.003) and haematoma volumes (135 ml vs. 295 ml; p=0.008). Globally unstable (Tile C) binder patients showed decreased sacroiliac diastasis (4.7 mm vs. 6.4 mm, p=0.04), without significant difference in haematoma volumes (284 ml vs. 234 ml, p=0.34). Four Tile C patients with binders demonstrated over-reduction resulting in pubic body over-ride. CONCLUSION: Rotationally unstable patients with binders have significantly less sacroiliac diastasis versus controls, corresponding with significantly lower haematoma volumes. KEY POINTS: • Haematoma segmentation and multiplanar caliper measurements provide new insights into binder effects. • Binder reduction corresponds with decreased pelvic haematoma volume in rotationally unstable injuries. • Discrimination between rotational and global instability is important for management. • Several caliper measurement cut-offs discriminate between rotationally and globally unstable injuries. • Pubic symphysis over-ride is suggestive of binder over-reduction in globally unstable injuries.

An assessment of pelvic binder placement at a UK major trauma centre.

Introduction Pelvic binders are used to reduce the haemorrhage associated with pelvic ring injuries. Application at the level of the greater trochanters is required. We assessed the frequency of their use in patients with pelvic ring injuries and their positioning in patients presenting to a single major trauma centre. Methods A retrospective review of our trauma database was performed to randomly select 1000 patients for study from April 2012 to December 2016. Patients with a pelvic binder or a pelvic ring injury defined by the Young and Burgess classification were included. Computed tomography was used to identify and measure pelvic binder placement. Results 140 patients were identified: 110/140 had a binder placed. Of the total, 54 (49.1%) patients had satisfactory placement and 56 (50.9%) had unsatisfactory placement; 30/67 (44.8%) patients with a pelvic ring injury had no binder applied, of whom 6 (20%) had an unstable injury; 9/67 patients died. Discussion This is the first study assessing pelvic binder placement in patients at a UK major trauma centre. Unsatisfactory positioning of the pelvic binder is a common problem and it was not used in a large proportion of patients with pelvic ring injuries. This demonstrates that there is a need for continuing education for teams dealing with major trauma.

Quantitative Effect of Pelvic Position on Radiographic Assessment of Acetabular Component Position.

BACKGROUND: Intraoperative fluoroscopy aims to improve component position in total hip arthroplasty. Measurement bias related to image quality, however, has not been quantified. We aim to quantify measurement bias in the interpretation of acetabular component position as a function of pelvis and fluoroscopic beam position in a simulated supine total hip arthroplasty model. METHODS: Posterior-anterior pelvis and hip images were obtained using a previously described pelvic model with known acetabular component position. Pelvic position was varied in 5° increments of pelvis rotation (iliac-obturator) and tilt (inlet-outlet), and in 1 cm increments from beam center in cranial-caudal and medial-lateral planes. Multiple regression analyses were conducted to evaluate the relationship between the resulting bias in interpretation of component position relative to pelvis position. RESULTS: Anteversion and abduction measurement bias increased exponentially with increasing deviation in rotation and tilt. Greater bias occurred for anteversion than for abduction. Hip centered images were less affected by pelvis malposition than pelvis centered images. Deviations of beam center within 5 cm in the coronal plane did not introduce measurement bias greater than 5°. An arbitrarily defined acceptable bias of ±5° for both abduction and anteversion was used to identify a range of optimum pelvic positioning each for hip and pelvis centered imaging. CONCLUSION: Accurate measurement of acetabular component abduction and anteversion, especially anteversion, is sensitive to proper pelvic position relative to the chosen radiographic plane. An acceptable measurement bias of ±5° is achieved when the pelvis is oriented within a newly identified range of optimum pelvic positioning.

Good functional outcome in patients suffering fragility fractures of the pelvis treated with percutaneous screw stabilisation: Assessment of complications and factors influencing failure.

BACKGROUND: Low energy pelvic ring fractures in the elderly have traditionally been treated conservatively, a treatment with potential long-term complications and loss of self-independence. Percutaneous screw stabilisation of the posterior pelvic ring is a new treatment modality that enables immediate mobilisation. The aim of this study was to assess the functional outcome after sacroiliac stabilisation in the elderly. METHODS: All elderly patients with a surgically stabilised low energy pelvic fracture between 2010 and 2015 were included. In 2016 a radiographic follow up and functional test was performed at least one year postoperative. RESULTS: The 50 operated patients had a mean age of 79 years and a one-year mortality of 10% (5/50). Only six patients lost independency after the pelvic fracture and moved to nursing home. The mean Timed Up and Go test was 16s at follow-up. The operation of the posterior pelvic ring averaged 63min with a radiation equal to a diagnostic pelvic CT. One intra-foraminally placed screw was immediately removed and 9 patients were later re-operated on due to symptomatic loosening of one or more screws. No loosening of screws was seen in 11 patients where both S1 and S2 were stabilised and out of 23 trans-sacral screws (crossing both sacroiliac joints) only two loosened. DISCUSSION: CT guided stabilisation of the posterior pelvis is safe and most patients resumed good function and independent living. The risk of a revision operation was 20%, but trans-sacral screw stabilisation in both S1 and S2 could reduce the risk of implant loosening.

Minimally invasive transforaminal lumbar interbody fusion with expandable versus static interbody devices: radiographic assessment of sagittal segmental and pelvic parameters.

OBJECTIVE Minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF) has been adopted as an alternative technique to hasten recovery and minimize postoperative morbidity. Advances in instrumentation technologies and operative techniques have evolved to maximize patient outcomes as well as radiographic results. The development of expandable interbody devices allows a surgeon to perform MIS-TLIF with minimal tissue disruption. However, sagittal segmental and pelvic radiographic outcomes after MIS-TLIF with expandable interbody devices are not well characterized. The object of this study is to evaluate the radiographic sagittal lumbar segmental and pelvic parameter outcomes of MIS-TLIF performed using an expandable interbody device. METHODS A retrospective review of MIS-TLIFs performed between 2014 and 2016 at a high-volume center was performed. Radiographic measurements were performed on lateral radiographs before and after MIS-TLIF with static or expandable interbody devices. Radiographic measurements included disc height, foraminal height, fused disc angle, lumbar lordosis, pelvic incidence, sacral slope, and pelvic tilt. Mismatch between pelvic incidence and lumbar lordosis were calculated for each radiograph. RESULTS A total of 48 MIS-TLIFs were performed, predominantly at the L4-5 level, in 44 patients. MIS-TLIF with an expandable interbody device led to a greater and more sustained increase in disc height when compared with static interbody devices. Foraminal height increased after MIS-TLIF with expandable but not with static interbody devices. MIS-TLIF with expandable interbody devices increased index-level segmental lordosis more than with static interbody devices. The increase in segmental lordosis was sustained in the patients with expandable interbody devices but not in patients with static interbody devices. For patients with a collapsed disc space, MIS-TLIF with an expandable interbody device provided superior and longer-lasting increases in disc height, foraminal height, and index-level segmental lordosis than in comparison with patients with static interbody devices. Using an expandable interbody device improved the Oswestry Disability Index scores more than using a static interbody device, and both disc height and segmental lordosis were correlated with improved clinical outcome. Lumbar MIS-TLIF with expandable or static interbody devices had no effect on overall lumbar lordosis, pelvic parameters, or pelvic incidence-lumbar lordosis mismatch. CONCLUSIONS Performing MIS-TLIF with an expandable interbody device led to a greater and longer-lasting restoration of disc height, foraminal height, and index-level segmental lordosis than MIS-TLIF with a static interbody device, especially for patients with a collapsed disc space. However, neither technique had any effect on radiographic pelvic parameters.