Acetabular fractures in geriatric patients: epidemiology, pathomechanism, classification and treatment options.

The incidence of geriatric acetabular fractures has shown a sharp increase in the last decades. The majority of patients are male, which is different to other osteoporotic fractures. The typical pathomechanism generally differs from acetabular fractures in young patients regarding both the direction and the amount of force transmission to the acetabulum via the femoral head. Geriatric fractures very frequently involve anterior structures of the acetabulum, while the posterior wall is less frequently involved. The anterior column and posterior hemitransverse (ACPHT) fracture is the most common fracture type. Superomedial dome impactions (gull sign) are a frequent feature in geriatric acetabular fractures as well. Treatment options include nonoperative treatment, internal fixation and arthoplasty. Nonoperative treatment includes rapid mobilisation and full weighbearing under analgesia and is advisable in non- or minimally displaced fractures without subluxation of the hip joint and without positive gull sign. Open reduction and internal fixation of geriatric acetabular fractures leads to good or excellent results, if anatomic reduction is achieved intraoperatively and loss of reduction does not occur postoperatively. Primary arthroplasty of geriatric acetabular fractures is a treatment option, which does not require anatomic reduction, allows for immediate postoperative full weightbearing and obviates several complications, which are associated with internal fixation. The major issue is the fixation of the acetabular cup in the fractured bone. Primary cups, reinforcement rings or a combination of arthroplasty and internal fixation may be applied depending on the acetabular fracture type.

Retrospective evaluation of radiological and clinical outcomes after surgical treatment of proximal femoral fractures utilizing PFNA and PFNA augmented.

INTRODUCTION: The primary aim of this study was to evaluate the clinical and radiological outcomes after surgical treatment of proximal femoral fractures utilizing the Proximal Femoral Nail Antirotation (PFNA), with the main focus on complications and reoperations. The secondary aim was to compare the outcomes of patients with and without cement augmentation of the cephalomedullary nails. MATERIALS AND METHODS: All patients with an acute proximal femoral fracture consequently treated with a PFNA between January 2011 and Dezember  2018 were evaluated. Clinical and radiological data were assessed for intra- and postoperative complications, including treatment failure. In addition, intra- and postoperative radiographs were used to determine the position of the implant, and any migration, via Tip-Apex-Distance (TAD) and the caput-collum-diaphyseal angle (CCD). The accuracy of the fracture reduction was rated according to Baumgaertners criteria. RESULTS: Two hundred sixty-four consecutive patients (mean age 78.8 ± 12.0; 73.1% female) were included. The predominant OTA/AO fracture classification was 31A1 (153 cases, 58.0%). The average duration of surgery was 63.1 ± 28.0 min and showed no significant differences between PFNA and PFNA with augmentation. The implant positioning was rated as good in 222 cases (84.1%). Two hundred sixty-three patients (99.6%) showed evidence of healing within the time frame of three months postoperatively, one case of delayed union healed after secondary dynamization. During the observational period, 18 patients (6.8%) required a total of 23 additional surgeries. Overall, a lower reoperation rate was observed following the use of the augmentation option (2/86 patients (2.3%) vs. 16/178 patients (9.0%), p = 0.04). In particular, there were no cases of cut-out or cut-through among patients who underwent augmentation as part of osteosynthesis. CONCLUSIONS: Overall reoperation rate after surgical treatment of proximal femoral fractures utilizing the Proximal Femoral Nail Antirotation (PFNA) was 6.8%, with 23 additional surgeries performed in 18 patients. The usage of the PFNA with augmentation showed equally good implant positioning, excellent healing rates and fewer postoperative complications compared to the PFNA implant alone with a similar overall duration of surgery.

Hip arthroscopy with initial access to the peripheral compartment for femoroacetabular impingement: midterm results from a large-scale patient cohort.

BACKGROUND: Hip arthroscopy with initial access to the peripheral compartment could reduce the risk of iatrogenic injury to the labrum and cartilage; furthermore, it avoids the need for large capsulotomies with separate portals for peripheral and central (intra-articular) arthroscopy. Clinical results of the peripheral-compartment-first technique remain sparse, in contrast to those of conventional hip arthroscopy starting in the intra-articular central compartment. The purpose of this study was to assess outcome of hip arthroscopy with the peripheral-compartment-first technique, including complication rates, revision rates and patient-reported outcome scores. MATERIALS AND METHODS: This outcome study included 704 hips with femoroacetabular impingement. All arthroscopies were performed using the peripheral-compartment-first technique. A joint replacement registry and the institutional database were used to assess the revision and complication rates, while patient-reported outcome measures were used to assess functional outcomes and patient satisfaction. RESULTS: In total, 704 hips (615 patients) were followed up for a mean of 6.2 years (range 1 to 9 years). The mean age of the patients was 32.1 ± 9.2 years. During the follow-up period, 26 of 704 (3.7%) hips underwent total hip arthroplasty (THA) after a mean of 1.8 ± 1.2 years, and 18 of the 704 (2.6%) hips required revision hip arthroscopy after a mean of 1.2 ± 2.1 years. 9.8% of the hips had an unsatisfactory patient-reported outcome at final follow-up. CONCLUSIONS: The results for the peripheral-compartment-first technique were promising. We recommend a well-conducted randomized controlled clinical trial to guide future therapeutic recommendations regarding the most favorable hip arthroscopy technique. LEVEL OF EVIDENCE: Level IV, therapeutic study. TRIAL REGISTRATION: This study was registered at ClinicalTrials.gov (U.S. National Library of Medicine; ID: NCT05310240).

Midterm Results of AAA Ankle Arthroplasty.

BACKGROUND: Outcome reports for Alpha Ankle Arthroplasty (AAA), a third-generation implant relying on a mobile bearing design for total ankle replacement, are sparse. This retrospective study evaluated the midterm survivorship, clinical, and radiologic outcomes after implantation of this implant. METHODS: For 64 patients who received 65 Triple A ankle implants between 2009 and 2020, implant survival was calculated using the Kaplan-Meier curve. Clinical outcomes were evaluated by measuring the range of motion, stability, Western Ontario and McMaster Universities Osteoarthritis Questionnaire score (WOMAC), and American Orthopaedic Foot & Ankle Society ankle-hindfoot score (AOFAS). The average pain level and satisfaction with the postoperative result were rated on a numeric rating scale (0-10). Additionally, radiologic analysis was performed using anteroposterior and lateral radiographs and tibiotalar alignment was assessed. RESULTS: The implant-survival rate was 61.5% at a mean follow-up of 8.2 years. Twenty-five patients (38.5%) required revision surgery (average time to revision, 3.1 years, 95% CI 2.1-4.1 years). For patients without revisions, the average range of motion in dorsiflexion and plantarflexion were 3.6 ± 4.2 degrees and 21.9 ± 7.8 degrees, respectively. The mean WOMAC and AOFAS scores were 44.7 ± 47.5 and 75.1 ± 14.0, respectively. The average pain and subjective satisfaction scores were 2.0 ± 1.7 and 8.5 ± 1.9, respectively. Mean alignment values did not differ significantly for patients who required revision surgery. CONCLUSION: We found a high revision rate with use of the AAA. However, patients who did not require revision surgery had, on average, high satisfaction and good functional outcomes. LEVEL OF EVIDENCE: Level IV, case series.

Neurological recovery after early versus delayed surgical decompression for acute traumatic spinal cord injury.

The aim of this study was to determine whether early surgical treatment results in better neurological recovery 12 months after injury than late surgical treatment in patients with acute traumatic spinal cord injury (tSCI). Patients with tSCI requiring surgical spinal decompression presenting to 17 centres in Europe were recruited. Depending on the timing of decompression, patients were divided into early (≤ 12 hours after injury) and late (> 12 hours and < 14 days after injury) groups. The American Spinal Injury Association neurological (ASIA) examination was performed at baseline (after injury but before decompression) and at 12 months. The primary endpoint was the change in Lower Extremity Motor Score (LEMS) from baseline to 12 months. The final analyses comprised 159 patients in the early and 135 in the late group. Patients in the early group had significantly more severe neurological impairment before surgical treatment. For unadjusted complete-case analysis, mean change in LEMS was 15.6 (95% confidence interval (CI) 12.1 to 19.0) in the early and 11.3 (95% CI 8.3 to 14.3) in the late group, with a mean between-group difference of 4.3 (95% CI -0.3 to 8.8). Using multiply imputed data adjusting for baseline LEMS, baseline ASIA Impairment Scale (AIS), and propensity score, the mean between-group difference in the change in LEMS decreased to 2.2 (95% CI -1.5 to 5.9). Compared to late surgical decompression, early surgical decompression following acute tSCI did not result in statistically significant or clinically meaningful neurological improvements 12 months after injury. These results, however, do not impact the well-established need for acute, non-surgical tSCI management. This is the first study to highlight that a combination of baseline imbalances, ceiling effects, and loss to follow-up rates may yield an overestimate of the effect of early surgical decompression in unadjusted analyses, which underpins the importance of adjusted statistical analyses in acute tSCI research.

The acetabular roof reinforcement plate for the treatment of displaced acetabular fractures in the elderly: results in 59 patients.

INTRODUCTION: Open reduction and internal fixation is considered the gold standard of treatment for displaced acetabular fractures in younger patients. For elderly patients with osteoporotic bone quality, however, primary total hip arthroplasty (THA) with the advantage of immediate postoperative mobilization might be an option. The purpose of this study was to evaluate the clinical and radiological outcomes of surgical treatment of displaced osteoporotic acetabular fractures using the acetabular roof reinforcement plate (ARRP) combined with THA. MATERIALS AND METHODS: Between 2009 and 2019, 84 patients were operated using the ARRP combined with THA. Inclusion criteria were displaced osteoporotic fractures of the acetabulum with or without previous hemi- or total hip arthroplasty, age above 65 years, and pre-injury ability to walk at least with use of a walking frame. Of the 84 patients, 59 could be followed up after 6 months clinically and radiographically. Forty-nine (83%) were primary fractures and 10 (17%) periprosthetic acetabular fractures. RESULTS: The mean age was 80.5 years (range 65-98 years). The average time from injury to surgery was 8.5 days (range 1-28). Mean time of surgery was 167 min (range 100-303 min). Immediate postoperative full weight bearing (FWB) was allowed for 51 patients (86%). At the 6-month follow-up, all 59 patients except one showed bony healing and incorporation of the ARRP. One case developed a non-union of the anterior column. No disruption, breakage or loosening of the ARRP was seen. Additional CT scans performed in 18 patients confirmed bony healing. Twenty-six patients (44%) had regained their pre-injury level of mobility. Complications requiring revision surgery occurred in 8 patients. Five of them were suffering from a prosthetic head dislocation, one from infection, one from hematoma and one from a heterotopic ossification. CONCLUSIONS: The ARRP has proven to provide sufficient primary stability to allow for immediate FWB in most cases and represents a valuable option for the surgical management of displaced acetabular fractures in this challenging patient group.

Single column plate plus other column lag screw fixation vs. both column plate fixation for anterior column with posterior hemitransverse acetabular fractures - a biomechanical analysis using different loading protocols.

OBJECTIVES: Open reduction and internal fixation of both columns is considered the treatment of choice for displaced anterior column with posterior hemitransverse (ACPHT) fractures in non-geriatric patients. Plate fixation of one column combined with lag screw fixation of the other column allows to decrease operative time and approach-related morbidity compared to conventional both column plating. The aim of this biomechanical study was to evaluate whether single column plate plus other column lag screw fixation confers similar stability to both column plate fixation. Physiological loads were simulated using both the single-leg stance (SLS) as well as the sit-to-stand (STS) loading protocols. METHODS: A clinically relevant ACPHT fracture model was created using fourth-generation composite hemipelves. Fractures were stabilized with three different fixation constructs: (1) anterior column plate plus posterior column screw fixation (AP+PCS), posterior column plate plus anterior column screw fixation (PP+ACS) and anterior column plate plus posterior column plate fixation (AP+PP). Specimens were loaded from 50 to 750 N with a ramp of 100 N/s. Fracture gap motion (FGM) and relative interfragmentary rotation (RIFR) between the three main fracture fragments were assessed under loads of 750 N using an optical 3D measurement system. RESULTS: STS loading generally resulted in higher mean FGM and RIFR than STS loading in the AP+PCS and AP+PP groups, while no significant differences were found in the PP+ACS group. Compared to conventional both column plate fixation (AP+PP), PP+ACS displayed significantly higher FGM and RIFR between the iliac wing and the posterior column during SLS loading. No significant differences in FGM and RIFR were identified between the AP+PCS and the AP+PP group. CONCLUSION: Overall, single column plate plus other column lag screw fixation conferred similar stability to conventional both column plate fixation. From a clinical point of view, AP+PCS appears to be the most attractive alternative to conventional AP+PP for internal fixation of ACPHT fractures.

An alphanumeric classification of osteoporotic pelvic ring injuries.

INTRODUCTION: Classification and management of osteoporotic pelvic ring injuries (OPRI) continue to pose a considerable challenge to orthopaedic traumatologists. The currently used fragility fractures of the pelvis (FFP) classification of OPRI has recently been shown to have significant weaknesses. The aim of this study therefore was to propose a new, simple, yet comprehensive alphanumeric classification (ANC) of OPRI and to assess its intra- and interobserver reliability. Furthermore, its potential advantages over the FFP classification are discussed. MATERIALS AND METHODS: One hundred consecutive CT scans from patients with OPRI were evaluated by three orthopaedic traumatologists with varying levels of experience and one musculoskeletal radiologist. Intra- and interobserver reliability of the proposed classification system was assessed using weighted kappa (κ) statistics and percentage agreement. In addition, the Fleiss' kappa statistic was computed to assess interobserver agreement among all four raters. RESULTS: Overall intraobserver reliability of the proposed ANC was substantial [κ ranging from 0.71 to 0.80; percentage agreement: 70% (range, 67-76%)]. Overall interobserver reliability between pairs of raters was substantial as well [κ ranging from 0.61 to 0.68; percentage agreement: 58% (range, 53-61%)]. For ANC types, groups and subgroups, intra- and interobserver reliability were substantial to almost perfect. Interobserver agreement among all four raters was moderate to substantial, with Fleiss' kappa values of 0.48, 0.69, 0.71 and 0.52 for ANC overall, types, groups and subgroups, respectively. CONCLUSION: The proposed ANC of OPRI demonstrated overall reliability comparable to that of the FFP classification. The ANC, however, is simple, more comprehensive, and consistently relates to injury severity.

Biomechanical comparison of fixation techniques for transverse acetabular fractures - Single-leg stance vs. sit-to-stand loading.

OBJECTIVES: To biomechanically compare five different fixation techniques for transverse acetabular fractures using both the single-leg stance (SLS) and the sit-to-stand (STS) loading protocols and to directly compare fracture gap motion (FGM) and relative interfragmentary rotation (RIFR). METHODS: Transtectal transverse acetabular fractures were created on fourth-generation composite hemipelves in a reproducible manner. Five different fixation techniques were biomechanically assessed using both an SLS and STS loading protocol: anterior plate (AP) only, posterior plate (PP) only, anterior plate plus posterior column screw (AP+PCS), posterior plate plus anterior column screw (PP+ACS) and anterior plus posterior plate (AP+PP). After preconditioning, the specimens were loaded from 50 to 750 N with a ramp of 100 N/s. FGM and RIFR under loads of 750 N were measured using an optical 3D measurement system. RESULTS: In the three groups of fixation techniques addressing both columns, STS loading resulted in higher mean FGM and in RIFR than SLS loading. No construct failure was observed. In the single plate groups (AP only and PP only), STS loading resulted in failure of all specimens before reaching loads of 750 N, while no failure occurred after SLS loading. No significant differences in FGM and RIFR were found between the double plate (AP+PP) and the single plate plus column screw (AP+PCS and PP+ACS) techniques. CONCLUSION: SLS loading appeared to overestimate the strength of acetabular fracture fixation constructs and STS loading may be more appropriate to provide clinically relevant biomechanical data. Internal fixation of a single column might not provide adequate stability for transverse fractures, while strength of single plate plus column screw fixation and double plate fixation was comparable.

Mid-term Follow-up of the Direct Anterior Approach in Acetabular Revision Hip Arthroplasty Using a Reconstruction Cage With Impaction Grafting.

BACKGROUND: Severe acetabular bone loss is often treated with reconstruction cages and impaction grafting using allograft bone. Accurate implant positioning is crucial for successful clinical and radiological outcomes. The direct anterior approach (DAA) is a standard approach for primary total hip arthroplasty (THA) that is being used more frequently for revision THA. The aim of this study was to report midterm clinical and radiological outcomes of acetabular revision arthroplasty using the DAA to address large acetabular defects by using a reconstruction cage and impaction grafting. METHODS: Acetabular cup revisions were performed in 64 patients (64 hips) with severe acetabular bone loss. All patients received reconstruction cages with impaction grafting via the DAA. The stem was also revised in 22 patients. Complications, radiological, and functional outcomes were assessed. RESULTS: Six of the 64 patients were revised at a mean follow-up of 27.6 months (range, 11-84 months), two each for implant failure, infection, and recurrent dislocation. One hip showed the radiological failure of the implant, but the patient was asymptomatic and was not revised. The median Western Ontario McMasters Osteoarthritis Score (WOMAC) for the cohort overall improved significantly (P < .01) by the latest follow-up compared with preoperative scores. CONCLUSION: Good midterm outcomes can be obtained with the DAA for acetabular cup revisions done to address severe acetabular bone loss by using reconstruction cages and impaction grafting. The number of complications was within the expected range for this type of revision procedure at midterm follow-up, and dislocation rates were low.

Fluoroscopically guided acetabular posterior column screw fixation via an anterior approach.

OBJECTIVE: Safe posterior column screw fixation via an anterior approach under two-dimensional fluoroscopic control. INDICATIONS: Anterior column with posterior hemitransverse fractures (ACPHF); transverse fractures; two-column fractures and T­type fractures without relevant residual displacement of the posterior column after reduction of the anterior column and the quadrilateral plate. CONTRAINDICATION: Acetabular fractures requiring direct open reduction via a posterior approach; very narrow osseous corridor in preoperative planning; insufficient intraoperative fluoroscopic visualization of the anatomical landmarks. SURGICAL TECHNIQUE: Preoperative planning of the starting point and screw trajectory using a standard pelvic CT scan and a multiplanar reconstruction tool. Intraoperative fluoroscopically controlled identification of the starting point using the anterior-posterior (ap) view. Advancing the guidewire under fluoroscopic control using the lateral-oblique view. Lag screw fixation of the posterior column with cannulated screws. POSTOPERATIVE MANAGEMENT: Partial weight bearing as advised by the surgeon. Postoperative CT scan for the assessment of screw position and quality of reduction of the posterior column. Generally no implant removal. RESULTS: In a series of 100 pelvic CT scans, the mean posterior angle of the ideal posterior column screw trajectory was 28.0° (range 11.1-46.2°) to the coronal plane and the mean medial angle was 21.6° (range 8.0-35.0°) to the sagittal plane. The maximum screw length was 106.3 mm (range 82.1-135.0 mm). Twelve patients were included in this study: 10 ACPHF and 2 transverse fractures. The residual maximum displacement of the posterior column fracture component in the postoperative CT scan was 1.4 mm (0-4 mm). There was one intraarticular screw penetration and one perforation of the cortical bone in the transition zone between the posterior column and the sciatic tuber without neurological impairment.

Preoperative planning and safe intraoperative placement of iliosacral screws under fluoroscopic control.

OBJECTIVE: Preoperative planning of the starting point and safe trajectory for iliosacral screw (SI screw) fixation using CT scans for safe and accurate fluoroscopically controlled percutaneous SI screw placement. INDICATIONS: Transalar and transforaminal sacral fractures. SI joint disruptions and fracture-dislocations. Non- or minimally displaced spinopelvic dissociation injuries. CONTRAINDICATIONS: Transiliac instabilities. Sacral fractures with neurological impairment requiring decompression. Relevant residual displacement after closed reduction attempts. Insufficient fluoroscopic visualization of the anatomical landmarks of the upper sacrum. SURGICAL TECHNIQUE: Preoperative planning of the starting point and the safe screw trajectory using CT scans and two-dimensional multiplanar reformation tools. Fluoroscopically guided identification of the starting point using the lateral view according to preoperative planning. Advancing the guidewire under fluoroscopic control using inlet and outlet views according to the planned trajectory. Predrilling and placement of 6.5 mm cannulated screws. POSTOPERATIVE MANAGEMENT: Weightbearing as tolerated using crutches. Immediate CT scan in case of postoperative neurological impairment. Generally no screw removal. RESULTS: Fifty-nine screws were placed in 34 patients using the described technique. There were 2 cases of screw malpositioning (anatomical landmarks inadequately identified and fluoroscopically controlled SI screw fixation should thus not have been performed at all; in a case with sacral dysmorphism, preoperative planning suggested a posterior and/or caudal S1 starting point, respectively, but intraoperatively, selection of a different starting point and screw trajectory resulted in screw malpositioning with iatrogenic L5 nerve palsy).

Ultrasound melted polymer sleeve for improved primary pedicle screw anchorage: A novel augmentation technique.

BACKGROUND: Cement augmentation of pedicle screws to prevent screw loosening is associated with significant complications, such as cement leakage or bone necrosis. Therefore, an alternative strategy to improve pedicle screw anchorage has been recently developed: Polymer reinforcement of pedicle screws uses an in situ melted polymer sleeve in order to enhance screw anchorage. This biomechanical study evaluated the effect of polymer-reinforcement by comparing polymer-reinforced pedicle screws to non-augmented as well as cement-augmented screws under cyclic loading. METHODS: For each of the two comparisons (polymer-reinforced vs. non-augmented screws and polymer-reinforced vs. cement-augmented screws), polymer-reinforced screws and control screws were placed into the left and right pedicle of seven vertebrae (mean age: 74.0 (SD 9.3) years) to allow for pairwise left-right comparisons. Each screw was subjected to cyclic cranio-caudal loading with an initial load ranging from -50 N to +50 N and with stepwise increasing compressive loads (5 N every 100 cycles) until screw loosening. FINDINGS: Polymer-reinforced pedicle screws resisted a higher number of load cycles until loosening than the contralateral non-augmented control screws (4300 SD 2018 vs. 2457 SD 1116 load cycles, p = 0.015). Screw anchorage of polymer-reinforced pedicle screws was comparable to that of cement augmented control screws (3857 (SD2085) vs. 4300 (SD1257) load cycles until failure, p = 0.64). INTERPRETATION: Our findings indicate that polymer-reinforcement significantly enhances pedicle screw anchorage in low quality bone and that its effect is similar in size than that of cement augmentation.

Risk factors for nonunion after intramedullary nailing of subtrochanteric femoral fractures.

INTRODUCTION: Nonunion is a common complication after intramedullary nailing of subtrochanteric femoral fractures. A more detailed knowledge, particularly of avoidable risk factors for subtrochanteric fracture nonunion, is thus desired to develop strategies for reducing nonunion rates. The aim of the present study therefore was to analyse a wide range of parameters as potential risk factors for nonunion after intramedullary nailing of subtrochanteric fractures. MATERIALS AND METHODS: Seventy-four patients who sustained a subtrochanteric fracture and were treated by femoral intramedullary nailing at a single level 1 trauma centre within a 6-year period were included in this study. A total of 15 patient-related, fracture-related, surgery-related, mechanical and biological parameters were analysed as potential risk factors for nonunion. Furthermore, the accuracy of each of these parameters to predict nonunion was calculated. RESULTS: Nonunion occurred in 17 of 74 patients (23.0%). Of the 15 potential risk factors analysed, only 3 were found to have a significant effect on the nonunion rate (p < 0.05): postoperative varus malalignment, postoperative lack of medial cortical support and autodynamisation of the nail within the first 12 weeks post-surgery. Accuracy of each of these 3 parameters to predict nonunion was > 0.70. Furthermore, the nonunion rate significantly increased with the number of risk factors (no risk factor: 2.9%, one risk factor: 23.8%, two risk factors: 52.9%, and three risk factors: 100% [Chi-square test, p = 0.001)]. CONCLUSIONS: Our study indicates that intraoperative correction of varus malalignment and restoration of the medial cortical support are the most critical factors to prevent nonunion after intramedullary nailing of subtrochanteric femoral fractures. In addition, autodynamisation of the nail within the first 3 months post-surgery is a strong predictor for failure and should result in revision surgery.

Spondylotic traumatic central cord syndrome: a hidden discoligamentous injury?

PURPOSE: To revisit the concept of spondylotic traumatic central cord syndrome (TCCS) by assessing the frequency of discoligamentous injury and to correlate magnetic resonance imaging (MRI) and intraoperative findings. METHODS: A retrospective analysis of twenty-three consecutive patients (mean age: 62.7 ± 14.8 years) with profound spondylotic TCCS after acute cervical hyperextension trauma but without signs of instability on initial CT scans who underwent anterior surgical decompression and fusion was performed. Sensitivity and specificity of MRI in the detection of anterior longitudinal ligament disruption were calculated. The topographic relations between surgically verified segmental instabilities and spinal cord signals on MRI were analyzed. The cervical MRI scans of all patients were evaluated by the radiologist on call at time of admission, re-assessed by a specialized MRI radiologist for the purpose of this study and compared with intraoperative findings. RESULTS: Intraoperative findings revealed 25 cervical spine segments with hyperextension instability in 22 of 23 (95.7%) patients. The radiologist on call correctly assessed segmental hyperextension instability in 15 of 25 segments (sensitivity: 0.60, specificity: 1.00), while the specialized MRI radiologist was correct in 22 segments (sensitivity: 0.88, specificity: 1.00). In 17 of 23 (73.9%) patients, the level of spinal cord signal on MRI matched the level of surgically verified segmental instability. CONCLUSIONS: Our findings challenge the traditional concept of spondylotic TCCS as an incomplete cervical spinal cord injury without discoligamentous injury and emphasize the importance of MRI as well as the radiologist's level of experience for the assessment of segmental instability in these patients. These slides can be retrieved under Electronic Supplementary Material.

Inter- and intraobserver reliability and critical analysis of the FFP classification of osteoporotic pelvic ring injuries.

INTRODUCTION: The classification and management of osteoporotic pelvic ring injuries (OPRI) remain challenging. The fragility fractures of the pelvis (FFP) classification system proposed by Rommens and Hofmann constitutes the first comprehensive classification system of OPRI and may contribute to a more thorough assessment and grading of these injuries. The reliability of the FFP classification system, however, has not been evaluated yet. The purpose of this study therefore was to determine the inter- and intraobserver reliability of the FFP classification system and to critically analyse its strengths and weaknesses. MATERIALS AND METHODS: One-hundred pelvic CT scans obtained from a consecutive series of patients aged 70 years and older who sustained a low-energy pelvic ring injury were included in this study. Three orthopaedic traumatologists of varying levels of experience (one experienced pelvic surgeon, one consultant, one resident) and one musculoskeletal radiologist independently classified each OPRI according to the FFP classification in two different sessions. Intra- and interobserver reliability were determined using percentage agreement and Cohen's Kappa coefficients. RESULTS: The observed relative distribution of FFP fracture types was comparable to that reported in the original study by Rommens and Hofmann. Overall interobserver reliability for all 100 cases was moderate with Kappa values from 0.42 to 0.59 (mean percentage agreement: 61% (54%-68%)), while intraobserver reliability was substantial with Kappa values from 0.68 to 0.72 (mean percentage agreement: 77% (76%-78%)). Subgroup analysis revealed lowest reliability for the classification of Type IIc, IIIc and IVb injuries (32 cases). Within this subgroup of combined anterior and posterior OPRI involving a complete nondisplaced or displaced (uni- or bilateral) sacral fracture, Kappa values for interobserver reliability ranged from 0.10 to 0.52, while those for intraobserver reliability ranged from 0.29 to 0.66. CONCLUSION: Overall interobserver reliability of the FFP classification system was moderate, while intraobserver reliability was substantial. Despite the acceptable overall reliability, classification of FFP subtypes involving a complete nondisplaced or displaced sacral fracture showed relatively poor reliability. The latter limits the usefulness of the FFP classification for both clinical and research purposes and needs to be addressed in future studies.

Effect of pedicle screw augmentation with a self-curing elastomeric material under cranio-caudal cyclic loading-a cadaveric biomechanical study.

BACKGROUND: Pedicle screws can be augmented with polymethylmethacrylate (PMMA) cement through cannulated and fenestrated pedicle screws to improve screw anchorage. To overcome the drawbacks of PMMA, a modified augmentation technique applying a self-curing elastomeric material into a balloon-created cavity prior to screw insertion was developed and evaluated. The aim of the study was to compare the effect of the established and novel augmentation technique on pedicle screw anchorage in a biomechanical in vitro experiment. METHODS: In ten lumbar vertebral bodies, the right pedicles were instrumented with monoaxial cannulated and fenestrated pedicle screws and augmented in situ with 2 ml PMMA. The left pedicles were instrumented with monoaxial cannulated pedicle screws. Prior to left screw insertion, a balloon cavity was created and filled with 3 ml of self-curing elastomer (silicone). Each screw was subjected to a cranio-caudal cyclic load starting from - 50 to 50 N while the upper load was increased by 5 N every 100 load cycles until loosening or 11,000 cycles (600 N). After cyclic loading, a pullout test of the screws was conducted. RESULTS: The mean cycles to screw loosening were 9824 ± 1982 and 7401 ± 1644 for the elastomer and PMMA group, respectively (P = 0.012). The post-cycling pullout test of the loosened screws showed differences in the failure mode and failure load, with predominantly pedicle/vertebrae fractures in the PMMA group (1188.6 N ± 288.1) and screw pullout through the pedicle (671.3 N ± 332.1) in the elastomer group. CONCLUSION: The modified pedicle screw augmentation technique involving a balloon cavity creation and a self-curing elastomeric silicone resulted in a significantly improved pedicle screw anchorage under cyclic cranio-caudal loading when compared to conventional in situ PMMA augmentation.

Correction to: A simple approach for the preoperative assessment of sacral morphology for percutaneous SI screw fixation.

In the original article, co-author's given name has been published incorrectly. The correct given name should be Vinzent Kevin.

Monosegmental anterior column reconstruction using an expandable vertebral body replacement device in combined posterior-anterior stabilization of thoracolumbar burst fractures.

INTRODUCTION: In combined posterior-anterior stabilization of thoracolumbar burst fractures, the expandable vertebral body replacement device (VBRD) is typically placed bisegmentally for anterior column reconstruction (ACR). The aim of this study, however, was to assess feasibility, outcome and potential pitfalls of monosegmental ACR using a VBRD. In addition, clinical and radiological outcome of monosegmental ACR was related to that of bisegmental ACR using the same thoracoscopic technique. METHODS: Thirty-seven consecutive neurologically intact patients with burst fractures of the thoracolumbar junction (T11-L2) treated by combined posterior-anterior stabilization were included. Monosegmental ACR was performed in 18 and bisegmental ACR in 19 patients. Fracture type and extent of vertebral body comminution were determined on preoperative CT scans. Monosegmental and bisegmental kyphosis angles were analyzed preoperatively, postoperatively and at final radiological follow-up. Clinical outcome was assessed after a minimum of 2 years (74 ± 45 months; range 24-154; follow-up rate 89.2%) using VAS Spine Score, RMDQ, ODI and WHOQOL-BREF. RESULTS: Monosegmental ACR resulted in a mean monosegmental and bisegmental surgical correction of - 15.6 ± 7.7° and - 14.7 ± 8.1°, respectively. Postoperative monosegmental and bisegmental loss of correction averaged 2.7 ± 2.7° and 5.2 ± 3.7°, respectively. Two surgical pitfalls of monosegmental ACR were identified: VBRD positioning (1) onto the weak cancellous bone (too far cranially to the inferior endplate of the fractured vertebra) and (2) onto a significantly compromised inferior endplate with at least two (even subtle) fracture lines. Ignoring these pitfalls resulted in VBRD subsidence in five cases. When relating the clinical and radiological outcome of monosegmental ACR to that of bisegmental ACR, no significant differences were found, except for frequency of VBRD subsidence (5 vs. 0, P = 0.02) and bisegmental loss of correction (5.2 ± 3.7° vs. 2.6 ± 2.5°, P = 0.022). After exclusion of cases with VBRD subsidence, the latter did not reach significance anymore (4.9 ± 4.0° vs. 2.6 ± 2.5°, P = 0.084). CONCLUSIONS: This study indicates that monosegmental ACR using a VBRD is feasible in thoracolumbar burst fractures if the inferior endplate is intact (incomplete burst fractures) or features only a single simple split fracture line (burst-split fractures). If the two identified pitfalls are avoided, monosegmental ACR may be a viable alternative to bisegmental ACR in selected thoracolumbar burst fractures to spare a motion segment and to reduce the distance for bony fusion.