Purpose. To evaluate the use of cutaneous marking of the sacrum for percutaneous iliosacral screw fixation. Iliosacral screw placement is dependent upon spatial perception, multiplanar fluoroscopic imaging, and an appreciation of pelvic anatomy which often makes learning the technique difficult for residents. Cutaneous marking of the sacrum may facilitate iliosacral screw insertion by providing additional cues to the orientation of the sacrum. Method. A cross-over study design was used for placing iliosacral screws in whole cadaver specimens using standardized operative and imaging techniques with and without cutaneous sacral markings. Lateral fluoroscopic imaging and a radio-opaque straight edge were used to trace the lateral profile of the sacrum with a marking pen. Total procedure time and fluoroscopy time were recorded. A total of 14 residents (6 seniors and 8 juniors) each placed two iliosacral screw guide-wires in a total of seven whole cadavers (14 SI joints). Group 1 performed the procedure first with no markings and then with markings. Group 2 performed the procedure first with markings and then without markings. Statistical analysis included T test, Wilcoxon Rank Sum Test, and Signed-Rank Test for Difference (p = 0.05). Participants also reported their opinions on each technique. Results. Mean procedure time for Group 1 was 8.83 minutes (3.77 17.17) and mean fluoroscopy time was 0.77 minutes (0.4 1.2) for the no-marking attempt and 10.33 min (5.88 15.25) and 1.06 min (0.6 2.3) respectively for the marking attempt. Mean procedure time for Group 2 was 11.3 min (6.33 16.5) and mean fluoroscopy time was 1.19 min (0.6 2.3) for the marking attempt and 7.22 min (2.83 17.27) and 0.97 min (0.4 1.8) respectively for the no-marking attempt. There were no significant differences between groups. T test analysis of all marking vs. no marking showed no significant difference for total procedure time (p= O.7020) or fluoroscopy time (p= 0.8297). Wilcoxon Rank Sum Test analysis showed no significant difference for total procedure time (p= 0.4415) or fluoroscopy time (p=0.7486) and Signed-Rank Test for Difference showed no significant difference for total procedure time (p=0.0625) or fluoroscopy time (p=0.1459). Senior residents reported they found the cutaneous marking helpful and would use it again whereas junior residents had mixed feelings on its utility. Conclusion. Cutaneous marking of the sacrum did not significantly impact total procedure time or fluoroscopy time but was generally reported to be helpful for residents learning percutaneous iliosacral screw fixation

Sacral fractures are often underdiagnosed, but are frequent in the setting of pelvic ring injuries. They are mostly caused by high velocity injuries or they can be pathological in aetiology. We sought to assess the clinical outcomes of the surgically treated unstable sacral fractures, with or without neurological deficits. unstable sacral fractures were included in the study. Single centre, prospectively collected data, retrospective review of patients who sustained vertically unstable fractures of the sacrum who underwent surgical fixation. out of a total of 432 patients with pelvis and acetabulum injuries. fifty six patients met the inclusion criteria. 18 patients had sustained zone one injuries. 14 patients had zone 2 injuries and 10 patients had zone 3 injurie. Operative fixation was performed percutaneously using cannulated screws in 18 patients.. Open fixation of the sacrum using the anterior approach in 6 patients. Posterior approach was indicates in all 10 of the zone 3 injuries of the sacrum. While in 4 patients, combined approaches were used. 3 patients had decompression and spinopelvic fixation. Neurological deficits were present in 16% of the patients. 2 patients presented with neurgenic bladder. Of the 4 patients who had neurological fall out, 3 resolved with posterior decompression and posterior fixation. All 4 neurological deficits were due to taction or compression of the nerve roots. No hardware failures or non unions observed. The rate of neurological deficit was related more to the degree of pelvic ring instability than to a particular fracture pattern. Low rates of complications and successful surgical treatment of sacral fractures is achiavable. Timeous accurate diagnosis mandatory

Dysmorphic pelves are a known risk factor for malpositioned iliosacral screws. Improved understanding of pelvic morphology will minimise the risk of screw misplacement, neurovascular injuries and failed fixation. Existing classifications for sacral anatomy are complex and impractical for clinical use. We propose a CT-based classification using variations in pelvic anatomy to predict the availability of transosseous corridors across the sacrum. The classification aims to refine surgical planning which may reduce the risk of surgical complications. The authors postulated 4 types of pelves. The “superior most point of the sacroiliac joint” (sSIJ) typically corresponds with the mid-lower half of the L5 vertebral body. Hence, “the anterior cortex of L5” (L5. a. ) was divided to reference 3 distinct pelvic groups. A 4. th. group is required to represent pelves with a lumbosacral transitional vertebra. The proposed classification:. A – sSIJ is above the midpoint of L5. a. B – sSIJ is between the midpoint and the lowest point of L5. a. C – sSIJ is below the lowest point of L5. a. D – pelves with a lumbosacral transitional vertebra. Specific measures such as the width of the S1 and S2 axial and coronal corridors and the S1 lateral mass angles were used to differentiate between pelvic types. Three-hundred pelvic CT scans were classified into their respective types. Analysis of the specific measures mentioned above illustrated the significant difference between each pelvic type. Changes in the size of S1 and S2 axial corridors formed a pattern that was unique for each pelvic type. The intra- and inter-observer ratings were 0.97 and 0.95 respectively. Distinct relationships between the sizes of S1 and S2 axial corridors informed our recommendations on trans-sacral or iliosacral fixation, number and orientation of screws for each pelvic type. This classification utilises variations in the posterior pelvic ring to offer a planning guide for the insertion of iliosacral screws

Hip instability is one of the most common causes for total hip arthroplasty (THA) revision surgery. Studies have indicated that lumbar fusion (LF) surgery is a risk factor for hip dislocation. Instrumented spine fusion surgery decreases pelvic tilt, which might lead to an increase in hip motion to accommodate this postural change. To the best of our knowledge, spine-pelvis-hip kinematics during a dynamic activity in patients that previously had both a THA and LF have not been investigated. Furthermore, patients with a combined THA and LF tend to have greater disability. The purpose was to examine spine-pelvis-hip kinematics during a sit to stand task in patients that have had both THA and LF surgeries and compare it to a group of patients that had a THA with no history of spine surgery. The secondary purpose was to compare pain, physical function, and disability between these patients. This cross-sectional study recruited participants that had a combined THA and LF (n=10; 6 females, mean age 73 y) or had a THA only (n=11; 6 females, mean age 72 y). Spine, pelvis, and hip angles were measured using a TrakSTAR motion capture system sampled at 200 Hz. Sensors were mounted over the lateral thighs, base of the sacrum, and the spinous process of the third lumbar,12th thoracic, and ninth thoracic vertebrae. Participants completed 10 trials of a standardized sit-to-stand-to-sit task. Hip, pelvis, lower lumbar, upper lumbar, and lower thoracic sagittal joint angle range of motion (ROM) were calculated over the entire task. In addition, pain, physical function, and disability were measured with clinical outcomes: Hip Disability Osteoarthritis Outcome Score (pain and physical function), Oswestry Low Back Disability Questionnaire (disability), and Harris Hip Score (pain, physical function, motion). Physical function performance was measured using 6-Minute Walk Test, Stair Climb Test, and 30s Chair Test. Angle ROMs during the sit-to-stand-to-sit task and clinical outcomes were compared between THA+LF and THA groups using independent t-tests and effect sizes (d). The difference in hip ROM was approaching statistical significance (p=0.07). Specifically, the THA+LF group had less hip ROM during the sit-to-stand-to-sit task than the THA only group (mean difference=11.17, 95% confidence interval=-1.13 to 23.47), which represented a large effect size (d=0.83). There were no differences in ROM for pelvis (p=0.54, d=0.28) or spinal (p=0.14 to 0.97; d=0.02 to 0.65) angles between groups. The THA+LF group had worse clinical outcomes for all measures of pain, physical function, and disability (p=0.01 to 0.06), representing large effect sizes (d=0.89 to 2.70). Hip ROM was not greater in the THA+LF group, and thus this is unlikely a risk factor for hip dislocation during this specific sit-to-stand-to-sit task. Other functional tasks that demand greater excursions in the joints should be investigated. Furthermore, the lack of differences in spinal and pelvis ROM were likely due to the task and the THA+LF group had spinal fusions at different levels. Combined THA+LF results in worse clinical outcomes and additional rehabilitation is required for these patients

Bertolotti first described articulation of the L5 transverse process with the sacrum as a cause of back pain in 1917. Since then little attention has been payed to these atypical articulations despite their high reported incidence. Here we describe our early experience of surgical treatment and propose a validated CT based classification of lumbosacral segment abnormalities (LSSA). 400 lumbosacral CT scans were reviewed (NBT), a classification devised and incidence of abnormalities recorded. 40 patients were selected and 4 independent observers classified each scan. Case notes for all patients (C&V) who received steroid injections into or surgical excision of LSSAs were reviewed. Results as follows:. 5 types of abnormality were identified. Type 0 - normal. Type 1 - asymmetrical shortening of the iliolumbar ligament. Type 2 - transverse process of L5 within 2mm of the sacrum. Type 3 - diarthrodial joint (3A: no evidence of degeneration 3B: degenerative change). Type 4 - transverse process and sacrum have fused. Type 5 - extends to L4. 54.5% of patients had abnormalities. The kappa values for the intra-observer results were 0.69 to 0.88 and the inter-observer ratings gave a combined score of over 0.7 indicating substantial agreement. Our CT classification of LSSAs is both straight forward to use and repeatable. The incidence of these abnormalities is higher in our population of CT scans compared to previous published series using plain radiographs. All patients treated with surgical excision of established articulations (Type 3A or above) reported good or excellent outcomes following excision

Aim. Squamous cell carcinoma (SCC) is a rare but often devastating complication of chronic osteomyelitis. Optimum diagnosis and management are not well established. This paper aimed to develop a definitive, evidence-based approach to its diagnosis and management. Method. A systematic review of relevant published studies available in English from 1999-present was conducted. Strict inclusion criteria ensured that the diagnoses of osteomyelitis and SCC were explicit and valid. Additional cases from our institution were included using the same eligibility criteria. Data regarding patient demographics, osteomyelitis diagnosis, SCC diagnosis and its management and patient outcomes were collected. Statistical significance was assessed by Fisher's exact test. Results. Nineteen publications involving 98 patients plus eight patients managed locally were included. Eighty percent of patients were male, diagnosed with SCC at an average age of 59 years old (24–82 years), 31 years after their osteomyelitis diagnosis (3–67 years). Multiple bones were affected: tibia or fibula (59%), femur (17%), pelvis and sacrum (8%), bones of the foot and ankle (8%) and upper limbs (6%). Malignant transformation was associated predominantly with sinus (82%), ulceration (61%) and discharge (41%). SCC was diagnosed by biopsy (77%) or incidentally (23%) following definitive management for osteomyelitis. Twenty-two percent of patients had a staging CT scan. Seventy-six percent of patients underwent amputation, 16% underwent limb-sparing wide local excision and the remaining patients were palliated. Incidental diagnosis of SCC was associated with poorer outcomes in terms of death or disease recurrence (one year, p=0.052, five years p=0.021, Fisher's exact test) as was metastatic disease at SCC diagnosis (one year, p=0.006, five years, p=0.032, Fisher's exact test) and pelvic or sacral disease (one year p<0.001, five years p=0.002, Fisher's exact test). All patients who were not actively treated died within one year of SCC diagnosis. Data was suggestive that more patients who underwent amputation (versus wide local excision) were disease free at one and five years, but this was not statistically significant (one year, p=0.058, five years, p= 0.152, Fisher's exact test). Conclusions. SCC should be suspected in all cases of chronic osteomyelitis with skin changes, particularly where changes exceed 3 years duration and involve the pelvis. Multiple biopsies for histology should be taken in all suspected cases, as well as routinely during surgical excision of osteomyelitis when chronic skin changes are present. Once SCC is identified, staging CT scan should be performed to guide management. Amputation, where possible, should be considered

Bone remodeling effects is a significant issue in predicting long term stability of hip arthroplasty. It has been frequently observed around the femoral components especially with the implantation of prosthesis stem. Presence of the stiffer materials into the femur has altering the stress distribution and induces changes in the architecture of the bone. Phenomenon of bone resorption and bone thickening are the common reaction in total hip arthroplasty (THA) which leading to stem loosening and instability. The objectives of this study are (i) to develop inhomogeneous model of lower limbs with hip osteoarthritis and THA and (ii) to predict the bone resorption behavior of lower limbs for both cases. Biomechanical evaluations of lower limbs are established using the finite element method in predicting bone remodeling process. Lower limbs CT-based data of 79 years old female with hip osteoarthritis (OA) are used in constructing three dimensional inhomogenous models. The FE model of lower limbs was consisted of sacrum, left and right ilium and both femur shaft. Bond between cartilage, acetabulum and femoral head, sacrum and ilium were assumed to be rigidly connected. The inhomogeneous material properties of the bone are determined from the Hounsfield unit of the CT image using commercial biomedical software. A load case of 60kg body weight was considered and fixed at the distal cut of femoral shaft. For THA lower limbs model, the left femur which suffering for hip OA was cut off and implanted with prosthesis stem. THA implant is designed to be Titanium alloy and Alumina for stem and femoral ball, respectively. Distribution of young modulus of cross-sectional inhomogeneous model is presented in Fig. 2 while model of THA lower limbs also shown in Fig. 2. Higher values of young modulus at the outer part indicate hard or cortical bone. Prediction of bone resorption is discussed with the respect of bone mineral density (BMD). Changes in BMD at initial age to 5 years projection were simulated for hip OA and THA lower limbs models. The results show different pattern of stress distribution and bone mineral density between hip OA lower limbs and THA lower limbs. Stress is defined to be dominant at prosthesis stem while femur experienced less stress and leading to bone resorption. Projection for 5 years follow up shows that the density around the greater tronchanter appears to decrease significantly

The purpose of this research was to determine the feasibility of radiostereometric analysis (RSA) as a diagnostic tool for assessing non-union following spinal arthrodesis procedures. Further, to estimate clinical thresholds for precision and accuracy of the proposed method in the cervical and lumbar spine. A three-level lumbo-sacral and a four-level cervical posterior arthrodesis procedures were performed on an artificial spine model (Sawbones, WA). Using a spring loaded inserter (RSA Biomedical, Sweden), eight to ten RSA markers were placed within each of the L4 and L5 segments in the spinous process (L4 only), lamina, transverse processes, posterior and anterior (down the pedicle) wall of the vertebral body. Eight to ten markers were placed within the proximal sacrum (S1) at the medial and lateral crests, tuberosity, and within the sacral canal wall. Four to eight RSA markers were placed into the C3-C6 lateral masses. Titanium screws and rods were applied to the spinal segments. Identical procedures were then performed on a cadaveric spine using similar bead placement and hardware. RSA imaging consisted of 12 double exams (24 exams) of the cervical and lumbar regions for both the Sawbones and cadaveric spine to assess precision of measurement under zero-displacement conditions. The most distal vertebrae were considered the datum against which the movement of all other vertebrae was compared. The artificial spine was then dismantled for accuracy assessment in which the middle vertebrae (L5 and C4-C5) were moved relative to the superior (L4 and C3) and inferior (S1 and C6) vertebrae by known, incremental displacements on an imaging phantom device. Displacements occurred along the superior-inferior, anterior-posterior, and flexion-extension (rotational) axes of motion. RSA images were obtained at each displacement. Image analysis was performed using model-based software (RSACore v3.41, Leiden, Netherlands) to visualize implanted RSA beads in 3-D space. Precision was defined as the 95% confidence interval of error in measuring zero-displacement. Accuracy was defined as the mean difference (with 95% confidence interval) between the known and measured displacement. The rate of RSA bead detection was high with 5–8 implanted beads being visible in both the lumbar and cervical regions of the artificial and cadaveric spines. Translational RSA precision for both spines was better than 0.25 mm and 0.82 mm for the lumbar and cervical regions, respectively. Rotational precision was better than 0.40° and 1.9° for the lumbar and cervical regions, respectively. RSA accuracy for the artificial spine overall demonstrated less than 0.11 mm translational bias (margin < ±0.02 mm) and less than 0.22° rotational bias (margin < ±0.15°). This study demonstrates that RSA achieves sufficient precision and accuracy to detect intervertebral micromotion for the purpose of assessing arthrodesis. Well dispersed RSA bead placement is critical to achieving sufficient accuracy as well as avoiding occlusion by metal hardware. Cervical bead implantation is particularly sensitive to bead clustering due to small vertebrae size and proximity to critical structures. The results of this work will aid in the development of a clinical study to assess arthrodesis in patients

Background. Over 10% of total hip arthroplasty (THA) surgeries performed in England and Wales are revision procedures. 1. Malorientation of the acetabular component in THA may contribute to premature failure. Yet with increasingly younger populations receiving THA surgery (through higher incidences of obesity) and longer life expectancy in general, the lifetime of an implant needs to increase to avoid a rapid increase in revision surgery in the future. The Evaluation of X-ray, Acetabular Guides and Computerised Tomography in THA (EXACT) trial is assessing the pelvic tilt of a patient by capturing x-rays from the patient in sitting, standing and step-up positions. It uses this information, along with a CT scan image, to deliver a personalised dynamic simulation that outputs an optimised position for the hip replacement. A clinical trial is currently in place to investigate how the new procedure improves patient outcomes. 2. . Our aim in this project was to assess whether accurate functional assessment of pelvic tilt could be further obtained using inertial measurement units (IMUs). This would provide a rapid, non-invasive triaging method such that only patients with high levels of tilt measured by the sensors would then receive the full assessment with x-rays. Methods. Recruited patients were fitted with a bespoke device consisting of a 3D-printed clamp which housed the IMU and fitted around the sacrum area. A wide elastic belt was fitted around the patient's waist to keep the device in place. Pelvic tilt is measured in a standing, flexed seated and step-up position while undergoing X-rays with the IMU capturing the data in parallel. Patients further completed another five repetitions of the movements with the IMU but without the x-ray to test repeatability of the measurements. Statistical analysis included measures of correlation between the X-ray and IMU measurements. Results. Data on 30 patients indicated a moderate-strong correlation (R. 2. =0.87) between IMU and radiological measures of pelvic tilt. Key message. A novel device has been developed that can suitably track pelvic movements to stratify patients into risk categories for post-operative dislocations

Crescent fractures are represented by a spectrum of morphological fracture patterns, sharing a common mechanism of injury. We propose three distinct types according to the extent of Sacroiliac (SI) joint involvement and the size of the crescent fragment, which enables a pragmatic choice of surgical approach and stabilisation technique. Crescent fractures are fracture dislocations of the SI joint in which there is variable amount of disruption of the SI ligaments extending proximally as a fracture of the posterior iliac wing. We identified three groups of Crescent fractures according to the extent of SI joint involvement, relationship of the fracture line to the S1 and S2 nerve root foramina on anteroposterior and outlet plain radiograph views, and CT films. Type I involves the less than inferior third of the SI joint with a large posterior iliac fragment left attached to the sacrum. This is best approached anteriorly for stabilisation. Type II has between one-third to two-thirds involvement of the SI joint and is treated according to Helfet's technique. Type III has a very small crescent fragment left attached to the sacrum and the inferior two-thirds of the SI joint is disrupted. This is treated with percutaneous SI screws, but will need anterior open reduction in delayed presentations. Based on this, we treated sixteen patients and followed them for at least two years. There were four Type I, four Type II and eight Type III fractures. Fifteen had anatomical reduction and stabilisation of the SI joint with good functional results. Delayed referral, the presence of significant soft tissue injury posteriorly and infected external fixator pins. From our experience we would like to propose this functional classification of crescent fractures which we find useful in making a choice of surgical approach and stabilisation technique to achieve satisfactory reduction and stabilisation of sacroiliac joint

Aims

Excision of chronic osteomyelitic bone creates a dead space which must be managed to avoid early recurrence of infection. Systemic antibiotics cannot penetrate this space in high concentrations, so local treatment has become an attractive adjunct to surgery. The aim of this study was to present the mid- to long-term results of local treatment with gentamicin in a bioabsorbable ceramic carrier.

Purpose. The aim of this study is to describe the influence of sitting and standing posture on sagittal pelvic inclination in preoperative total hip replacement patients to assist with correct acetabular component positioning. Methods. Lateral radiographs of the pelvis and lumbar spine in sitting and standing of preoperative hip arthroplasty patients with primary hip osteoarthritis were extracted. Pelvic tilt was measured using the vertical inclination of a line from the ASIS to pubic tubercle. Sacral inclination was measured as the angle between the anterior surface of the sacrum and a horizontal reference. Figure one is a representation of the pelvic tilt angle and sacrel inclination angle taken during standing. The Cobb angle of the lumbar spine was recorded represented for a sitting patient in figure 2. Hip flexion was recorded (figure 2). Results. 60 patients were identified. Mean age of the cohort was 63. Sacral inclination ranged from 1 to 55 degrees in standing with a mean of 25.7 degrees. In sitting, sacral inclination ranged from 0.3–84.5 degrees with a mean of 24.1 degrees. Pelvic tilt ranged from 30 degrees posteriorly to 21.5 degrees anteriorly in standing. Pelvic tilt in sitting and ranged from 48 posterior to 42 degrees anterior tiltLumbar lordosis ranged from 11.6 to 91.7 degrees in standing. Lumbar lordosis in sitting ranged from 29.5 degrees(kyphosis) to 42 degrees (lordosis). Total hip flexion was 107.4 degrees from standing to sitting. Conclusions. There is wide variability in pelvic orientation between individuals in both postures Orientating acetabular components for total hip arthroplasty should account for postural changes in native version

Squamous Cell Carcinoma (SCC) is a rare complication of chronic osteomyelitis (OM), arising in a sinus tract (Marjolin's Ulcer). We routinely send samples for histological analysis for all longstanding sinus tracts in patients with chronic osteomyelitis. We reviewed the clinical features and outcomes of patients with SCC arising from chronic osteomyellitis. A retrospective study was performed of patients with osteomyelitis between January 2004 and December 2014 in a single tertiary referral centre. Clinical notes, microbiology and histo-pathological records were reviewed for patients who had squamous cell carcinoma associated with OM. We treated 9 patients with chronic osteomyelitis related squamous cell carcinoma. The mean age at time of diagnosis was 51 years (range 41–81 years) with 4 females and 5 males. The mean duration of osteomyelitis was 16.5 years (3–30 years) before diagnosis of SCC. SCC arose in osteomyelitis of the ischium in 5 patients, sacrum in 1 patient, femur in 1 patient and tibia in 2 patients. Osteomyelitis was due to pressure ulceration in 7 patients and post-traumatic infection in 2 patients. The histology showed well differentiated SCC in 4 cases and moderately differentiated SCC in 2 cases with invasion. Two patients had SCC with involvement of bone. One patient had metastatic SCC to bowel. All patients had polymicrobial or Gram-negative cultures from microbiology samples. Four patients (57%) in our series died as result of their cancer despite wide resection. The mean survival after diagnosis of SCC was 1.3 years and mean age at time of death was 44.7 years. Two of these patients had ischial disease and were treated with hip disarticulation, hemi-pelvectomy and iliac node clearance. Five patients remain disease free at a mean of 3.4 years (range 0.1 – 7yrs) after excision surgery. One patient in this group underwent a through-hip amputation, one underwent an above knee amputation and one underwent excision of ischium and surrounding sinuses. Of note, all these patients had clear staging scans at time of diagnosis. This case series demonstrates the consequences of an uncommon complication of osteomyelitis. In our series only 3 patients underwent biopsy for suspected SCC due to clinical appearances. The other cases were all identified incidentally after routine histological sampling, demonstrating the importance of this practice

Purpose. To review the outcome of multilevel (≥4) instrumented lumbar fusion to sacrum / pelvis performed for degenerative conditions. Methods. Clinical data of 47 consecutive patients from 2002 to 2012 were reviewed retrospectively. Inclusion criteria included fusion from at least L2 to S1 / pelvis, i.e. minimum of 4 levels. Imaging was assessed for restoration of normal sagittal profile as well as subsequent fusion. EQ5D, OSD and VAS scores pre-op and at 6 months post op were analysed. Average age at surgery was 64 years (50–78). Thirteen cases were primary and 34 revisions. Indications were axial back pain either associated with sagittal imbalance (40%) or leg pain (36%) and leg pain alone in 10%. Results. The intra-operative blood loss averaged 2222 (250–7000) ml with 40% re-infusion from cell-saver. The average surgical duration was 268 minutes. Proximal extent of instrumentation was T2 (1), T3 (1), T4 (2), T8 (1), T9 (1), T10 (17), T11 (2), T12 (5), L1 (4) and L2 (13). TLIF's were done in 20 cases mostly at the base of the construct. Pedicle subtraction osteotomies were performed in 14 revision cases. Dural tears occurred in 14 cases, all revision cases except one. Wound infection occurred in 3 cases. Except for transient quadriceps weakness related to osteotomy, no neurological complications occurred. One patient deceased peri-operatively. Subsequent revision was required in 13 cases for instrumentation failure. OSD score improved by 15.3 points on average, which is clinically and statistically significant. Conclusion. Long lumbar fusions remain technically demanding with a high incidence of adverse events. This is due to the nature of revision surgery and high biomechanical demands on constructs. Surgical intervention can however be justified by the desperation of the cohort in terms of pain and poor function which can be modestly improved with this intervention. NO DISCLOSURES

Introduction. Unicompartmental knee arthroplasty is in particular promoted for knee OA patients with high demands on function and activity. This study used wearable inertial sensors to objectively assess function during specific motion tasks and to monitor activities of daily living to verify if UKA permits better function or more activity in particular with demanding tasks. Methods. In this retrospective, cross-sectional study, UKA patients (Oxford, n=26, 13m/13f, age at FU: 66.5 ±7.6yrs) were compared to TKA patients (Vanguard, n=26, 13m/13f, age: 66.0 ±6.9yrs) matched for gender, age and BMI (29.5 ±4.6) at 5 years follow-up. Subjective evaluation of pain, function, physical activity and awareness of the joint arthroplasty was performed by means of four PROMs: VAS pain, KOOS-PS, SQUASH (activity) and Forgotten Joint Score (FJS),. Objective measurement of function was performed using a 3D inertia sensor attached to the sacrum while performing gait test, sit-stand and block-step tests. To derive functional parameters such as walking cadence or sway during transfers or step-up previously validated algorithms were used (Bolink et al., 2012). Daily physical activity was objectively monitored with a 3D accelerometer attached to the lateral side of the unaffected upper leg during four consecutive days. Activity parameters (counts and times of postures, steps, stairs, transfers, etc.) were also derived using validated algorithms. Data was analysed using independent T-test, Mann-Whitney U test and Pearson's correlation. Results. PROM's did not show any significant difference between UKA and TKA especially for the routinely used VAS-Pain and KOOS-PS (p>0.57) while higher (better) mean scores were recorded for UKA using more specialist measures such as self-reported activity (SQUASH; UKA vs TKA: 5659 ±3753 vs 4245 ±2489, p=0.12) and joint awareness (FJS; UKA vs TKA: 50.7 ±24.3 vs 41.4 ±29.2, p=0.08). Sensor based measures of function showed significantly higher walking cadence for UKA (107.9 ±10.5 steps/min) than TKA (102.2 ±10.9 steps/min, p=0.049). Other functional parameters also indicated better UKA function, e.g. forward sway during sit-stand (UKA vs TKA: 38.0 ±13.2 deg vs 43.2 ±10.7 deg, p=0.06). The wearable activity monitors showed that UKA patients perform significantly more steps downwards on stairs or slopes (89.0 ±77.4) than TKA patients (46.9 ±51.3, p=0.03). Other, less demanding activity counts such as daily steps (6522 vs 6343, p=0.85) or sit-stand transfers (39.4 vs 42.3, p=0.37) were not different. Discussion and Conclusion. PROM's could not differentiate UKA from TKA although more specialist or demanding scores such SQUASH (activity) or FJS (joint awareness) seem to have more power. Objective assessment could show for UKA faster cadence and more steps down on stairs and slopes, indicating that UKA benefits functional quality and enables demanding activities. Objective measures of function and activity may be required in routine clinical follow-up to provide evidence and wearable sensors may facilitate this

Background. Resection of sacral chordoma remains challenging because complex anatomy and important nerves in the sacrum make it difficult to achieve wide surgical margins. Computer-assisted navigation has shown promise in aiding in optimal preoperative planning and in providing accurate and precise tumour resection during surgery. Purpose. To evaluate the benefit of using computer-assisted navigation in precise resection of sacral chordoma. Methods. From 2007 to 2012, we performed sacral chordoma resections with computer-assisted navigation in 19 consecutive patients, of which 15 were primary and 4 were recurrent. There were 11 male and 8 female patients with a mean age of 53.5 years (range, 36–81 years). Eighteen lesions had their upper extent above S3 and the remaining one was below S3. Reconstructed three-dimensional images were used to plan the bone resection before operation. Five patients were treated with CT-based navigation system. 14 cases got ISO-C scanned during operation and CT and MR images were fused using the navigation software. Results. The mean intra-operative blood loss was 2821 mL and the mean operating time was 300 minutes. The mean deviation of registration during operation was 1.5 mm. Wide margins and marginal margins proved by specimen evaluation were achieved in 3 patients and 14 patients, respectively. Two patients received extensive curettage followed by post-operative radiation. With mean 25.1 (range, 7–60) months of follow-up, the overall local recurrence rate was 10.5% (2/19). No recurrence was observed in 15 primary patients treated with wide or marginal margins. A second local recurrence occurred in 2 out of 4 recurrent patients. One was treated with extensive curettage and the other with marginal margin resection. Conclusion. Computer-assisted navigation allows precise execution of intended tumour resection and therefore may improve the local control of sacral chordoma. Comparative clinical studies with long-term follow-up are necessary to confirm this benefit

Purpose. Curative treatment of malignancies in the sacrum and lumbar spine frequently requires en-bloc spinopelvic resection. There is no standard classification of these procedures. We present a classification of these resections based on analysis of 45 consecutive cases of oncologic spinopelvic resections. This classification implies a surgical approach, staging algorithm, bony and soft tissue reconstruction, and functional outcomes following surgery. Method. We reviewed oncologic staging, surgical resections, and reconstructions of 45 consecutive patients undergoing spinopelvic resection with curative intent. Mean follow-up of surviving patients was 38 months. Common themes in these cases were identified to formulate the surgical classification. Results. Tumors included chondrosarcoma (n=11), other sarcomas (n=11), osteosarcoma (n=9), chordoma (n=6), locally invasive carcinoma (n=5), and others (n=3). Resections could be divided into 5 types based on the exent of the lumbosacral resection and the need for an associated external hemipelvectomy. Type 1 resections included a total sacrectomy +/− lumbar spine resection. Type 2 resections included hemisacrectomy +/− partial lumbar excision, and iliac wing resection. Type 3 resections encompassed external hemipelvectomy with hemisacrectomy +/− partial lumbar excision. Type 4 resections encompassed external hemipelvectomy with total sacrectomy +/− lumbar excision. Type 5 excisions involved hemicorporectomy type procedures. For each type of resection we have developed guidelines for trans- vs retroperitoneal surgical approaches, staging of the resections, bony and soft tissue reconstructive procedures to re-establish spinopelvic continuity, and predicted functional outcomes for patients. At mean 38 month follow-up on surviving patients, 28 are living and 17 are deceased. Twenty-two of 28 surviving patients are disease free. Nineteen of 26 surviving patients are independent in their activities of daily living. Conclusion. En bloc spinopelvic resections may be classified into five types based on the extent of lumbosacral excision and the need for concurrent hemipelvectomy. Using this classification system, we have formulated treatment strategies to guide surgical approach, procedural staging, bony and soft tissue reconstructive procedures, and expected functional outcomes. Long term survival and independent function can be achieved in this challenging patient population

INTRODUCTION. Mobile-bearing knee prostheses have been designed in order to provide less constrained knee kinematics compared to fixed-bearing prosthesis. Currently, there is no evidence to confirm the superiority of either of the two implants with regard to walking performances. It has been shown that subjective outcome scores correlate poorly with real walking performance and it has been recommended to obtain an additional assessment of walking ability with objective gait analysis. OBJECTIVES. We assessed recovery after total knee arthroplasty (TKA) with mobile- and fixed-bearing between patients during the first postoperative year, and at 5 years follow-up, using a new objective method to measure gait parameters in real life conditions. METHODS. 56 patients with mobile- and fixed-bearing of the same design were included in this randomised controlled double-blinded study and evaluated pre- and post-operatively at 6 weeks, 3 months, 6 months 1 year and 5 years. At each visit a WOMAC and Knee Society Score were calculated and each participant completed an EQ-5D questionnaire. To assess the patients' gait five miniature angular rate sensors mounted respectively on the sacrum and each shank and thigh measured lower limb movement and rotation. The patients walked 30 metres on a flat surface and gait parameters were recorded with a small ambulatory device in order to carry out an objective gait analysis. RESULTS. Objective recovery was strongly correlated with patients' age. When the whole population was considered, there was no significant difference between groups at any time in objective gait parameters. After separating the population according to their age (less than 71 years old, compared to those of more than 71 years old) a secondary analysis showed that the bearing type can lead to opposite results in different age groups. At five years follow-up, most of the recorded gait parameters (stride length, knee max rotation speed, shank and thigh range of motion, and limp) showed better results for mobile bearing in younger patients, while better gait performances were found systematically with fixed-bearing TKA in older patients. CONCLUSION. To our knowledge, this is the first study where similarly designed posterior-stabilised knee replacements with fixed- and mobile-bearing have been compared with gait analysis in real-life conditions. We observed systematically differences between mobile and fixed bearing groups, which are confirmed by multivariate analysis. Our results suggest that older patients might not benefit from a mobile bearing TKA and that extended age controlled study should be performed to identify an age, above which fixed bearing should not be the recommended choice. Before choosing the bearing type, surgeons should take into account the age of the patient

Minimally invasive placement of iliosacral screws (SI-screw) is becoming the standard surgical procedure for sacrum fractures. Computer navigation seems to increase screw accuracy and reduce intraoperative radiation compared to conventional radiographic placement. In 2012 an interdisciplinary hybrid operating theatre was installed at the University of Ulm. A floor-based robotic flat panel 3D c-arm (Artis zeego, Siemens, Germany) is linked to a navigation system (BrainLab Curve, BrainLab, Germany). With a single intraoperative 3D scan the whole pelvis can be visualised in CT-like quality. The aim of this study was to analyse the accuracy of SI-screws using this hybrid operating theater. 32 SI-screws (30 patients) were included in this study. Indications ranged from bone tumour resection with consecutive stabilisation to pelvic ring fractures. All screws were implanted using the hybrid operating theatre at the University of Ulm. We analysed the intraoperative 3D scan or postoperative computed tomography and classified the grade of perforation of the screws in the neural foramina and the grade of deviation of the screws to the cranial S1 endplate according to Smith et al. Grade 0 stands for no perforation and a deviation of less than 5 °. Grade 1 implies a perforation of less than 2 mm and a deviation of 5–10°, grade 2 a perforation of 2–4 mm and a deviation of 10–15° and grade 3 a perforation of more than 4 mm and a deviation of more than 15°. All patients were tested for intra- and postoperative neurologic complications and infections. The statistical analysis was executed using Microsoft Excel 2010. 32 SI-screws were implanted in the first 20 months after the hybrid operating theatre had been established in 2012. All 30 patients were included in this study (15 men, 15 women). The mean age was 59 years ±23 (13–95 years). 20 patients received a single screw in S1 (66.7%), 1 patient 2 unilateral screws in S1 and S2 (3.3%), one patient 2 bilateral screws in S1 (3.3%) and 8 patients a single screw stabilising both SI-joints (26.7%). 27 screws showed no perforation (84.4%), 1 screw a grade 1 perforation (3.1%) and 4 screws a grade 2 perforation (12.5%). There was no grade 3 perforation. Furthermore there was no perforation of the neural foramina or the ventral cortex in the axial plane of the SI-screws stabilising one SI-joint (24 screws). Only single SI-screws bridging both SI joints showed a perforation of the neural foramina (37% grade 0, 12.5% grade 1, 50% grade 2, 0% grade 3). In the frontal plane 23 screws (71.9%) showed a deviation of less than 5°. In 5 screws a grade 1 deviation (15.6%) and in 4 screws a grade 2 deviation (12.5%) could be found. There was no grade 3 deviation. There were no infections or neurological complications. The high image quality and large field of view in combination with an advanced navigation system is a great benefit for the surgeon. All SI-screws stabilising only one joint showed completely intraosseous placement. Single SI-screws bridging 2 SI-joints intentionally perforated the neural foramina ventrally in 5 cases because of dysmorphic sacral anatomy. This makes image-guided implantation of SI-screws in a hybrid operating theatre a very safe procedure

Introduction:. Acetabular cup position is an important factor in successful total hip arthroplasty (THA). Optimal cup placement requires surgeons to possess an accurate perception of pelvic orientation during cup impaction, however, varying pelvic anatomy and limited visual cues in the surgical field may interfere with this process. The purpose of this study was to evaluate the utility of an inertial measurement unit (IMU) in monitoring pelvic position during THA. Materials & Methods:. Ten patients scheduled to undergo THA were IRB-approved and consented by four surgeons. A small IMU was placed over the patient's sacrum pre-operatively and zeroed in standing position. Pelvic orientation data was streamed and captured wirelessly throughout the procedure. Surgeons were blinded to all data throughout the study period. Prior to cup impaction, the surgeon indicated his intended cup abduction angle and the degree to which the cup impactor was manipulated to compensate for perceived AP pelvic tilt. The degree of pelvic tilt as determined by the IMU (angle β) was then recorded (Figure 1). AP-pelvis radiographs were measured in Martell Hip Analysis Suite post-operatively to calculate the cup abduction angle, which was then compared to the surgeon's intended abduction angle to determine surgeon accuracy. To predict the final cup abduction angle, the degree of pelvic tilt recorded by the IMU (angle β) was subtracted from the abduction angle of the cup impactor (angle α) that was positioned using the OR table as a reference (Figure 1). This value was then compared to the measured post-operative cup abduction angle in order to assess the accuracy of the IMU in measuring pelvic tilt. Surgeon accuracy and IMU accuracy were compared to determine if the IMU was more or less effective than surgeon perception at determining pelvic tilt. Results:. The mean intended abduction angle indicated by the surgeons intraoperatively was 43.7° (range 40°–45°), while the mean measured post-operative abduction angle was 40.1° (range 25.9°–49.4°). In five of the cases, the surgeon's post-operative abduction angle fell within 2° of his intended abduction angle. One cup was placed at a higher than intended abduction angle (4.4°), and four cups were placed in lower than intended abduction angles by an average of 10.8° (range 3.9°–19.1°). Film analysis revealed that surgeons placed the acetabular cup on average 5.4 ± 6.0° from their intended abduction angle (range 0.3°–19.1°). Following analysis of the IMU offset data, it was observed that the IMU deviated on average 3.1 ± 2.6° (range 0.7°–7.2°) from its expected orientation value. The IMU deviated more than 2° from expected pelvic tilt in five cases. Discussion:. The IMU was able to ascertain AP pelvic tilt to a higher degree of accuracy than four surgeons using standard surgical techniques. A system in which the pelvis could be monitored and adjusted intraoperatively based on accurate IMU data would allow the surgeon to place the pelvis in optimal position prior to cup impaction, which could potentially increase overall cup positioning accuracy. More data is needed to confirm these results