Anteroposterior Images Research Articles

Use of anteroposterior view fluoroscopy for targeting percutaneous pedicle screws in cases of spinal deformity with axial rotation.

Over the past decade percutaneous pedicle screws have become popular for the minimally invasive treatment of spinal disorders. However, until the last 5 years the presence of a significant spinal deformity was regarded as a relative contraindication for percutaneous instrumentation. Recent advances in surgical technique and intraoperative technology have made percutaneous fixation in complex spinal pathologies more commonplace. The authors report their experience using a parsimonious method for uniplanar fluoroscopic targeting of pedicles in challenging cases. The authors performed a retrospective analysis of patients with adult spinal deformity who underwent percutaneous pedicle screw instrumentation from 2008 to 2013. Cases were included if a spiral slice postoperative CT scan was obtained. All cases had a minimum of 10° of axial rotation and typically had additional accompanying anatomical abnormalities. Screws were assessed for any pedicle violations as well as any impingement of the surrounding facet joints. A total of 410 pedicle screws were placed in 36 patients with an average 6.4 levels of instrumentation per patient. The mean age was 67 years (range 44-86 years) and there were 25 females. Of the 410 screws, 29 (7.1%) had some medial or lateral pedicle violation. Of these, 15 (3.7%) were Grade 1, 6 (1.4%) were Grade 2, and 8 (2.0%) were Grade 3 violations. Of the Grade 3 violations, 2 each were at the L-4, L-5, and S-1 levels, and 1 each was at the T-10 and L-1 levels. Two of the patients had symptoms and both underwent screw repositioning, one during the same admission and the other in a delayed fashion. Both were at the L-5 and S-1 levels with anatomically highly medialized pedicles. There were no motor deficits, and both removals were for numbness. Of the 72 screws at the proximal end of the construct, there were 6 facet violations (8.3%). Four (5.6%) of these were Grade 1, 1 (1.4%) was Grade 2, and 1 (1.4%) was Grade 3. The anteroposterior fluoroscopic technique can be effectively used by spinal surgeons to cannulate the pedicles in patients with rotational deformities. The complication rate in this challenging population is acceptable and is in accordance with the existing literature. However, caution should be used at L-5 and S-1 when the pedicle is narrow and highly medialized, rendering an indistinct medial wall on anteroposterior imaging.

Increasing source to image distance for AP pelvis imaging – Impact on radiation dose and image quality

AimA quantative primary study to determine whether increasing source to image distance (SID), with and without the use of automatic exposure control (AEC) for antero-posterior (AP) pelvis imaging, reduces dose whilst still producing an image of diagnostic quality. MethodsUsing a computed radiography (CR) system, an anthropomorphic pelvic phantom was positioned for an AP examination using the table bucky. SID was initially set at 110 cm, with tube potential set at a constant 75 kVp, with two outer chambers selected and a fine focal spot of 0.6 mm. SID was then varied from 90 cm to 140 cm with two exposures made at each 5 cm interval, one using the AEC and another with a constant 16 mAs derived from the initial exposure. Effective dose (E) and entrance surface dose (ESD) were calculated for each acquisition. Seven experienced observers blindly graded image quality using a 5-point Likert scale and 2 Alternative Forced Choice software. Signal-to-Noise Ratio (SNR) was calculated for comparison. For each acquisition, femoral head diameter was also measured for magnification indication. ResultsResults demonstrated that when increasing SID from 110 cm to 140 cm, both E and ESD reduced by 3.7% and 17.3% respectively when using AEC and 50.13% and 41.79% respectively, when the constant mAs was used. No significant statistical (T-test) difference (p = 0.967) between image quality was detected when increasing SID, with an intra-observer correlation of 0.77 (95% confidence level). SNR reduced slightly for both AEC (38%) and no AEC (36%) with increasing SID. ConclusionFor CR, increasing SID significantly reduces both E and ESD for AP pelvis imaging without adversely affecting image quality.

Changes of the retrolingual pharynx during the Muller manoeuvre and during sleep in sleep apnoea

ObjectiveTo determine whether the retrolingual pharynx shows the same morphometric modifications during the Muller manoeuvre and during drug-induced sleep endoscopy (DISE) with propofol in patients submitted for maxillomandibular advancement surgery. Subjects and methodsEighteen patients submitted for maxillomandibular advancement surgery (MMAS) were evaluated endoscopically before and 6 month after surgery in the region of the retrolingual pharynx while seated and lying in dorsal decubitus (supine) while performing the Muller manoeuvre and during DISE with propofol, to verify and measure if the same morphometric changes occur in the retrolingual pharynx during the Muller manoeuvre and during DISE with propofol. The area, anteroposterior, and laterolateral retrolingual pharynx images were acquired using the Sony Vegas 8.0 software and recorded on a DVD. The Image J software was used to measure and compare these images. ResultsAn increase in the pharyngeal aperture was observed in all measurements after surgery, specifically in area retrolingual pharynx images. When the Muller manoeuvre was performed, a greater gain (113%) in area retrolingual pharynx measurement was observed when the patient was awake and seated. With the patient was in dorsal decubitus during DISE with propofol there was a greater gain in area retrolingual pharynx measurement (201.33%) in the smaller aperture. ConclusionThe Muller manoeuvre after MMAS does not simulate the dimensions of the pharynx that occur during sleep.

Accuracy of fluoroscopically-assisted pedicle screw placement: analysis of 1,218 screws in 198 patients

Background contextWe retrospectively analyzed a total of 1,218 pedicle screws for accuracy, with postoperative computed tomography (CT), in 198 patients who were operated on between March 2004 and September 2012. PurposeTo determine the incidence of screw misplacement in patients who received a transpedicular screw fixation, with intraoperative fluoroscopy in the lateral and lateral with anteroposterior (AP) positions. The results are compared between the two groups. Study designRetrospective comparative study of accuracy of pedicle screw placement in thoracic and lumbar spine. Patient sampleThe sample consists of 198 consecutive patients who underwent transpedicular screw fixation. Outcome measuresAccuracy of screw placement was evaluated by postoperative CT scan. Misplacement was defined in cases where more than 25% of the screw size was residing outside the pedicle. MethodsThe indications for hardware placement, radiologic studies, patient demographics, and reoperation rates were recorded. Five hundred twenty-eight screws (Group A, n=81) were inserted into the vertebral body with the assistance of lateral fluoroscopy only, whereas 690 screws (Group B, n=117) were inserted with the assistance of lateral fluoroscopy, and the final positions of the screws were checked with AP fluoroscopy. ResultsA total of 1,218 screws were analyzed, with 962 screws placed at the lumbosacral region and 256 screws at the thoracic region. According to the postoperative CT scan, 27 screws (2.2%) were identified as breaching the pedicle. Nineteen of them (3.6%) were in Group A, whereas 8 (1.16%) were in Group B. The rate of pedicle breaches was significantly different between Group A and B (p=.0052). In Group A, the lateral violation of the pedicle was seen in 10 screws (1.9%), whereas medial violation was seen in 9 screws (1.7%). In Group B, the lateral violation of the pedicle was seen in six screws (0.87%), whereas medial violation was seen in two screws (0.29%). The medial and lateral penetration of screws were significantly different between Groups A and B (p<.05). A pedicle breach occurred in 21 patients, and 15 of them underwent a revision surgery to correct the misplaced screw. Of these patients, 11 (13.6%) were in Group A, and 4 (3.4%) were in Group B (p=.0335). ConclusionsIn this study, we evaluated and clarified the diagnostic value of intraoperative fluoroscopy in both the lateral and AP imaging that have not yet been evaluated in any comparative study. We concluded that the intraoperative use of fluoroscopy, especially in the AP position, significantly decreases the risk of screw misplacement and the results are comparable with other advanced techniques.

Automatic heart positioning method in computed tomography scout images.

Computed tomography (CT) radiation dose can be reduced significantly by region of interest (ROI) CT scan. Automatically positioning the heart in CT scout images is an essential step to realize the ROI CT scan of the heart. This paper proposed a fully automatic heart positioning method in CT scout image, including the anteroposterior (A-P) scout image and lateral scout image. The key steps were to determine the feature points of the heart and obtaining part of the heart boundary on the A-P scout image, and then transform the part of the boundary into polar coordinate system and obtain the whole boundary of the heart using slant elliptic equation curve fitting. For heart positioning on the lateral image, the top and bottom boundary obtained from A-P image can be inherited. The proposed method was tested on a clinical routine dataset of 30 cases (30 A-P scout images and 30 lateral scout images). Experimental results show that 26 cases of the dataset have achieved a very good positioning result of the heart both in the A-P scout image and the lateral scout image. The method may be helpful for ROI CT scan of the heart.

Multi-plate reconstruction for severe bicondylar tibial plateau fractures of young adults

This study was to evaluate clinical outcomes and complications following multi-plate reconstruction for treating severe bicondylar tibial plateau fractures of young adults. Between September 2007 and February 2012, 26 patients with severe bicondylar tibial plateau fractures met inclusion criteria; they were treated using multi-plate technique through combined approaches. Patients received an average follow-up of 40.8 (range, 18-64) months, which included anteroposterior and lateral imaging, postoperative complications, range of motion and stability of the knee. The Rasmussen score was applied for functional and radiological evaluation. Three to five plates were used for reconstruction. No intra-operative complications occurred. Postoperative complications included bulge of hardware in four patients and superficial dehiscence in three cases in the anterolateral incision of which one developed to deep infection. There was no neurovascular damage, and no implant breakage or loosening. Hardware was removed partly or totally in 16 cases. The average Rasmussen score at final follow-up was 27.2 (range, 21-30) points for functional evaluation and 16.4 (range, 14-18) for radiology. Multi-plate reconstruction is a valid and safe method for treating severe bicondylar tibial plateau fractures of young adults.

Gas in the rectum tends to reduce during radical external beam radiotherapy for localised prostate cancer

This study aims to clarify the time-course of gas accumulation in the rectum during treatment as guidance for the management of rectal volumes. We reviewed 2042 sets (35.2 sets per patient) of anteroposterior and right-left mega voltage (MV) images obtained for daily set-up from 58 patients who underwent radical external beam radiotherapy for localised prostate cancer. The patients were instructed to take magnesium oxide tablets during radiotherapy. They were also encouraged to avoid foods that might cause intestinal gas during radiotherapy. Gas accumulation in the rectum was graded into three classes by the same radiation oncologist. If no gas was seen in the rectum, it was classified as grade 0. A small amount of gas was classified as grade 1, whereas a marked amount of gas that required removal was classified as grade 2. Of the 2042 sets of MV images, grades 1 and 2 gas accumulation were seen in 332 (16%) and 156 (8%), respectively. By the trend test, gas accumulation significantly decreased towards the end of treatment (P = 0.02 for grade 1 or 2 and P = 0.02 for grade 2). On multivariate analysis, we did not identify any significant independent predictors for either baseline gas accumulation or gas reduction. Gas accumulation tended to decrease until the end of treatment. This tendency should be reconfirmed by other institutions.

Iliac screw placement in neuromuscular scoliosis using anatomical landmarks and uniplanar anteroposterior fluoroscopic imaging with postoperative CT confirmation

Neuromuscular scoliosis is a challenging pathology to treat. Surgical correction can involve long fusion constructs extending to the pelvis. The deformity inherent in these patients makes it difficult to obtain adequate lateral intraoperative radiographs for traditional image-guided placement of iliac screws. A clinical and radiographic assessment of 14 patients with neuromuscular spinal deformity was conducted. From 2007 to 2013, 12 of these patients (mean age 14.25 years, range 10-20 years) underwent long spinal instrumentation (mean 15 levels, range 10-18 levels) and fusion to the pelvis, and 2 underwent placement of a growing rod construct with iliac screw placement at a single institution. The average length of follow-up was 33.7 months (range 6-64 months). Iliac screws were placed after identifying the posterior superior iliac spine and using only anteroposterior fluoroscopy (view of the inlet of the pelvis), rather than the technique of direct palpation of the sciatic notch. The accuracy of iliac screw placement was assessed with routine postoperative CT. A total of 12 patients had 24 screws placed as part of a long-segment fusion to the pelvis, and 2 patients had two iliac screws placed as part of a growing rod construct for neuromuscular scoliosis. There were no iliac screw misplacements, and no complications directly related to the technique of iliac screw placement. For cases of definitive fusion (n = 12), the average coronal Cobb angle of patients with neuromuscular spinal deformity measured 62° before surgery and 44.3° immediately after surgery. The average preoperative thoracic kyphosis and lumbar sagittal lordosis measured 37.3° and 60.7°, respectively. Immediately after surgery, the thoracic and lumbar angles measured 30° and 41.1°, respectively. At last follow-up, the average coronal Cobb angle was maintained at 45.1°, and the thoracic and lumbar sagittal angles were maintained at 32.8° and 45.3°, respectively. A less invasive technique for iliac screw placement can be performed safely with a low likelihood of screw misplacement. This technique offers the biomechanical advantages of iliac fixation without the soft tissue exposure typically needed for safe screw insertion. The technique relies on identification of the posterior superior iliac spine and high quality anteroposterior fluoroscopic imaging for a view of the pelvic inlet.

Femoral Nerve Strain at L4–L5 Is Minimized by Hip Flexion and Increased by Table Break When Performing Lateral Interbody Fusion

Anatomic studies have demonstrated that nerves and blood vessels have excursion with extremity range of motion. We have measured femoral nerve excursion with the lateral lumbar transpsoas interbody fusion (LLIF) procedure with changes in table flexion and ipsilateral hip flexion on both sides of 5 cadavers. To determine the effect of hip range of motion on femoral nerve strain near the L4-L5 disc space because it pertains to the LLIF procedure. Postoperative thigh symptoms are common after the LLIF procedure. Although nerve strain in general has been shown to impair function, it has not been tested specifically with LLIF. Five cadavers were placed in the lateral position as though undergoing the L4-L5 LLIF procedure. Radiographical markers were implanted into the femoral nerve. Lateral and anteroposterior fluoroscopic images were recorded with 0° initial table flexion and the hip at 0, 20, 40, and 60° flexion. The table was flexed to 40°, and the process repeated. Examination was repeated on the contralateral side and nerve strain and excursion were calculated. Table flexion results in preloading the femoral nerve when approaching L4-L5. Nerve strain was highest with the table flexed to 40° and the hip at 0° (average, 6%-7%). Strain in the femoral nerve decreased with increasing hip flexion for both table flexion angles. Anterior displacement of the nerve by approximately 1.5 mm was noted at 40° table flexion compared with 0°. Strain values with table flexion of 40° approached those associated with reduced neural blood flow in animal studies. Table flexion should be minimized to the extent possible when performing L4-L5 LLIF. Additionally, hip flexion to 60° can neutralize the neural strain that occurs with aggressive table flexion. N/A.

Selective estrogen receptor modulation prevents scoliotic curve progression: radiologic and histomorphometric study on a bipedal C57Bl6 mice model

Previous work has suggested that progression of experimental scoliotic curves in pinealectomized chicken and bipedal C57BL6 mice models may be prevented and reversed with Tamoxifen treatment. Raloxifene is another Selective Estrogen Receptor Modulator (SERM) with estrogen agonist effects on bone and increases bone density but with fewer side effects on humans. To investigate whether scoliosis progression in bipedal C57Bl6 mice model could be prevented with SERM treatment and the mechanisms associated with this effect. Eighty C57BL6 mice were rendered bipedal and divided into Tamoxifen (TMX), Raloxifene (RLX) and control groups. TMX and RLX groups received orally administered TMX and RLX for 40weeks. Anteroposterior X-ray imaging and histomorphometric analysis (at 20th and 40th weeks) were performed. At 20th week, TMX and RLX groups displayed higher rates (p=0.033, p=0.029) and larger curve magnitudes (p=0.018). At 40th week, curve rates were similar between the groups but the curve magnitudes in TMX and RLX groups were smaller (p=0.001). Histomorphometry revealed that treated animals had higher trabecular density (p=0.04), lower total intervertebral disc (p=0.038) and growth plate volumes (p=0.005) and smaller vertebral bodies (p=0.016). Treatment with TMX or RLX did not reduce the incidence of scoliosis but decreased the curve magnitudes at 40weeks. The underlying mechanism associated with the decrease in curve magnitudes may be the early maturation of growth plates, thereby possible deceleration of the growth rate of the vertebral column and increase in bone density. RLX is as effective as TMX in preventing the progression of scoliotic curves in melatonin deficient bipedal mice.

Spectrum of Radiographic Femoroacetabular Impingement Morphology in Adolescents and Young Adults: An EOS-Based Double-Cohort Study

Symptomatic femoroacetabular impingement is a known prearthritic condition. Impingement morphology is poorly defined in the adolescent population. The purpose of this study was to document the prevalence of radiographic impingement morphology in adolescents with no symptomatic hip problems. Ninety anteroposterior images of the hip in forty-five consecutive adolescents with scoliosis met the inclusion criteria. Sex distribution was equal. The second cohort (ninety hips) was an age-matched group with no scoliosis. None had symptomatic hip problems. Images were analyzed for coxa profunda, protrusio acetabuli, Tönnis angle, anteroposterior alpha angle, center-edge angle, acetabular crossover, ischial spine sign, and neck-shaft angle. Of the 180 hips, 92.8% demonstrated at least one parameter suggesting impingement morphology, whereas 52.2% showed at least two signs. Evidence of coxa profunda was seen in 81.7% of the hips, while a negative Tönnis angle was seen in 31.1% and a center-edge angle indicative of acetabular overcoverage was seen in 15%. An acetabular crossover sign was detected in 27.2% of the hips, while an abnormal anteroposterior alpha angle was found in 5.6% of the hips in male patients and 6.7% of the hips in female patients. Statistical analysis revealed that abnormal alpha angles (p = 0.029), crossover signs (p = 0.029), and ischial spine signs (p = 0.026) were more common in the cohort without scoliosis, and coxa profunda was more common in females (p = 0.034). There was a high prevalence of radiographic impingement morphology beyond the spectrum of normal in this double-cohort study of adolescents. Femoroacetabular impingement remains a dynamic problem, and we caution against relying only on the use of hard-set static radiographic parameters when evaluating femoroacetabular impingement. This study raises the important question of what morphologic characteristics should be defined as abnormal, when at least one finding of impingement morphology is noted in such a large segment of the population. On the basis of the normative data obtained, reference values for radiographic parameters of femoroacetabular impingement morphology should be redefined. Normal values for a Tönnis angle were between -8° and 14°, the upper limit of the center-edge angle was 44°, and the normal values for femoral neck-shaft angle were between 121° and 144°. Surgical indications should be tailored to physical examination findings and not radiographic findings alone.

Evaluation of the Alpha Angle in Asymptomatic Adult Hip Joints: Analysis of 994 Hips

Numerous studies on cam femoroacetabular impingement (FAI) causing osteoarthritis have been conducted in Western populations, but not in Asian populations. The alpha angle in cam type FAI can be measured by routine hip AP and axial radiographs. The purpose of this study was to determine the range of alpha angles in an asymptomatic Asian cohort. We performed a retrospective examination on 500 asymptomatic Asian adults (1000 hips) who underwent simultaneous spine MRI and hip coronal survey MRI for evaluation of back pain from December 2009 to March 2010. The alpha angle was measured on anteroposterior (AP) pelvic survey images. According to inclusion criteria, 372 hips of 186 men and 622 hips of 311 women were analysed. The mean alpha angles for men and women were 50.61° ± 7.61° and 49.82° ± 4.14°, respectively with no statistically significant differences (p = 0.063). Alpha angles of the two age groups (≥50 years old and <50 years old) were similar in both genders: 49.90° ± 6.88° versus 51.40° ± 8.30° in men (p = 0.060), and 50.61° ± 7.61° versus 49.82° ± 4.14° in women (p = 0.71). The frequency of pathologic alpha angle of men and women was 0.5% and 3.1%, respectively. After review of 994 asymptomatic adult hips, we found neither gender-specific nor age-specific differences in the alpha angle. The frequency of the pathological range of the alpha angle was notably rare, as compared to those of Western countries. We assume that these findings could be related to a low prevalence of FAI and idiopathic osteoarthritis of the hip in the Asian population.

AB1168 Clinical disease activity scores of knee joints in newly diagnosed JIA predicts reduction in bone pixel value detected by computed radiography

ObjectivesTo evaluate the relationship between Computed Radiography (CR) Pixel values and disease activity scores obtained for the knees of newly diagnosed Juvenile Idiopathic Arthritis (JIA) children.MethodsChildren with newly diagnosed untreated...

Defining the radiation “scatter cloud” in the interventional suite

We hypothesized that fluoroscopic imaging creates radiation fields that are unevenly scattered throughout the endovascular suite. We sought to quantify the radiation dose spectrum at various locations during imaging procedures and to represent this in a clinically useful manner. Digital subtraction imaging (Innova 4100; GE Healthcare, Waukesha, Wisc) of the abdomen and pelvis was performed on a cadaver in anteroposterior, left lateral, and right anterior oblique 45° projections. Radiation exposure was monitored in real time with DoseAware dosimeters (Phillips, Houston, Tex) in eight radial projections at distances of 2, 4, and 6 ft from the center of the imaged field, each at 5-ft heights from the floor. Three to five consecutive data points were collected for each location. At most positions around the angiographic table, radiation exposure decreased as the distance from the source emitter increased; however, the intensity of the exposure varied dramatically around the axis of imaging. With anteroposterior imaging, the radiation fields have symmetric dumbbell shapes, with maximal exposure perpendicular to the table at the level of the gantry. Peak levels at 4 and 6 ft from the source emitter were 2.4 times and 3.4 times higher, respectively, than predicted based on the inverse square law. Maximal radiation exposure was measured in the typical operator position 2 ft away and perpendicular to the table (4.99 mSv/h). When the gantry was rotated 45° and 90°, the radiation fields shifted, becoming more asymmetric, with increasing radiation doses to 10.9 and 69 mSv/h, respectively, on the side of the emitter. Minimal exposure is experienced along the axis of the table, decreasing with distance from the source (<0.77 mSv/h). Quantifiable and reproducible radiation scatter is created during interventional procedures. Radiation doses vary widely around the perimeter of the angiography table and change according to imaging angles. These data are easily visualized using contour plots and scatter three-dimensional mesh plots. Rather than the concentric circles predicted by the inverse square law, these data more closely resemble a "scatter cloud." Knowledge of the actual exposure levels within the endovascular environment may help in mitigating these risks to health care providers.

3D reconstruction of the lumbar vertebrae from anteroposterior and lateral dual-energy X-ray absorptiometry

Current vertebral fracture prevention measures use Dual-energy X-ray Absorptiometry (DXA) to quantify the density of the vertebrae and subsequently determine the risk of fracture. This modality however only provides information about the projected Bone Mineral Density (BMD) while the shape and spatial distribution of the bone determines the strength of the vertebrae. Quantitative Computed Tomography (QCT) allows for the measurement of the vertebral dimensions and volumetric densities, which have been shown to be able to determine the fracture risk more reliably than DXA. However, for the high cost and high radiation dose, QCT is not used in clinical routine for fracture risk assessment. In this work, we therefore propose a method to reconstruct the 3D shape and density volume of lumbar vertebrae from an anteroposterior (AP) and lateral DXA image used in clinical routine. The method is evaluated for the L2, L3 and L4 vertebra. Of these vertebrae a statistical model of the vertebral shape and density distribution is first constructed from a large dataset of QCT scans. All three models are then simultaneously registered onto both AP and lateral DXA image. The shape and volumetric BMD at several regions of the reconstructed vertebrae is then evaluated with respect to the ground truth QCT volumes. For the L2, L3 and L4 vertebrae respectively the shape was reconstructed with a mean (2RMS) point-to-surface distance of 1.00 (2.64) mm, 0.93(2.52) mm and 1.34(3.72) mm and a strong correlation (r > 0.82) was found between the trabecular volumetric BMD extracted from the reconstructions and from the same subject QCT scans. These results indicate that the proposed method is able to accurately reconstruct the 3D shape and density volume of the lumbar vertebrae from AP and lateral DXA, which can potentially improve the fracture risk estimation accuracy with respect to the currently used DXA derived areal BMD measurements.

The First SICOT Oral Presentation Award 2011: Imageless computer-assisted femoral component positioning in hip resurfacing: a prospective randomised trial

The aim of the study was to evaluate the effects of imageless computer-assisted surgery (CAS) on the accuracy of positioning of the femoral component and on the short-term clinical outcome in hip resurfacing (HR) using a randomised prospective design. A total of 75 consecutive patients undergoing HR were randomly allocated to CAS and conventional implantation, respectively. Preoperatively and six months post-operatively standardised pelvic anteroposterior X-ray images, the total Western Ontario and McMaster Universities Osteoarthritis Index, the Harris Hip Score and the EQ-5D utility index were evaluated in a blinded manner. The primary end point of the study was a post-operative femoral component malpositioning in five degrees or more either varus or valgus absolute deviation from the planned stem shaft angle. Patient demographics and algofunctional scores did not differ between the CAS and conventional implantation samples. Using CAS fewer femoral components were positioned in five or more degrees absolute deviation (4/37 vs 12/38, Fisher's exact p = 0.047; 95 % confidence interval for the primary end point's incidence difference: +3 %; +39 %); the respective incidences of five or more degrees of varus deviation were 0/37 vs 5/38. One conversion to a stemmed prosthesis (CAS group) was performed for periprosthetic femoral neck fracture. Radiological signs of superolateral femoral neck/implant impingement were observed in two cases (one CAS-based and one conventional implantation). The accuracy of femoral HR component positioning was significantly improved using CAS. However, one major complication necessitated early revision in the CAS group at six months of observation. Apart from that adverse event no inter-group differences were observed for the short-term clinical outcome. Future studies need to address the clinical long-term relevance of CAS in HR.

Measuring the osteochondral connection of the femoral head and neck in patients with impingement femoroacetabulare by determining the angle of two alpha in lateral and anteroposterior hip radiographic images

Femoroacetabular impingement, a pathophysiological mechanism of small morphological changes of the hip leads to early arthritic changes. The aim of this study was to present a simple method for the quantification of femoral head and neck junction in patients with cam form of femoroacetabular impingement, in standardized anteroposterior and profile DUNN 90 radiograms of the hips. In standardized anteroposterior and profile DUNN 90 images of the hips we determined the angle of 2 alpha, defined by our own original method. We tested 141 hips in 81 patients without clinical signs of femoroacetabular impingement, and 153 hips in 76 patients with clinically clear signs of femoroacetabular impingement. The value of the angle 2 alpha in anteroposterior hip radiograms was on average 113.7 degrees for the patients with clinical symptoms of impingement, and 84.2 degrees for the control group of patients (p < or = 0.0001), and in DUNN 90 profile radiography of the hip, the value of 2 alpha angle in the patients group was 97.2 degrees, and 74.6 degrees in the control group (p < or = 0.0001). The proposed method of determining the angle 2 alpha showed a high level sensitivity (97.8%) and specificity (98.7) and positive predictive value (98.6%). It was false positive in only 1.3%, and false negative in 2.12% of patients. Using standardized anteroposterior and profile radiographs of the hips, and without determination of femoral neck axis in patients with femoroacetabular impingement with the cam effect at the junction of the femoral head and neck, we proposed the method of measuring joint abnormalities of femoral head and neck junction, very capable to predict the disease development in an asymptomatic risk group of patients and high sensitive in the diagnosis of the disease in the group of patients.

Iliac crest osteotomy to enhance exposure of the L4–5 interspace in minimally invasive lateral transpsoas interbody fusion: a cadaveric feasibility study

Object Minimally invasive lateral transpsoas interbody fusion (LTIF) has emerged as a popular surgical technique in a remarkably short period of time. The authors' experience with this procedure and anecdotal evidence in the literature suggest that the iliac crest may occasionally prevent access to the L4–5 interspace during minimally invasive LTIF. The authors propose that removal of a minimal amount of ilium would allow for successful exposure of the L4–5 interspace in those cases with a “high-riding” iliac crest. Therefore, the objective of this study was to evaluate the feasibility of iliac osteotomy to enhance exposure of the L4–5 interspace for minimally invasive LTIF. Methods Twenty L4–5 minimally invasive LTIF procedures were performed on 10 cadavers. The L4–5 minimally invasive LTIFs were successfully completed in 13 of 20 attempts. In the remaining 7 cases, the iliac crest prevented perfect orthogonal access to the L4–5 interspace. An iliac osteotomy was performed until the tubular retractors could be perfectly aligned with the L4–5 interspace and minimally invasive LTIF accomplished. Anteroposterior fluoroscopic images were obtained before and after the osteotomies. The angle between the working instrument and the superior L-5 endplate was measured, as were craniocaudal displacement and the resected iliac area. Results Iliac osteotomy enabled completion of L4–5 minimally invasive LTIF in the 7 remaining cases. Iliac resection was minimal; an average of 4.92 cm2 of iliac surface was resected (range 2.08–8.27 cm2) to enable L4–5 access. Adequate working angles were maintained (average 3.3° change after resection) while significant caudal displacement of the tubular system was achieved (average 15.7 mm, range 5.2–27.6 mm). Conclusions A significant portion of patients may have a high-riding iliac crest and that may have had an impact on minimally invasive LTIF in this series; L4–5 cases are rare in relation to midlumbar spine cases in most minimally invasive LTIF patient series. Significant caudal displacement of the tubular system was achieved with minimal iliac osteotomy, ensuring access to the L4–5 interspace in all specimens while maintaining the minimally invasive philosophy behind minimally invasive LTIF.

Comparable Maintenance of Tibial Slope in Two High Tibial Osteotomy Techniques

Objectives:High tibial osteotomies (HTO) are commonly performed to correct coronal malalignment in young, active patients who have concomitant cartilage lesions and/or cruciate ligament insufficiency. An unintended change of native tibial slope can negatively affect both the strain on reconstructed cruciate ligaments and the contact forces on cartilage. Therefore, one of the goals when performing an HTO is to minimize any change in posterior tibial slope. This study was designed to determine if there is a time zero difference in the maintenance of native tibial slope when performing valgus producing opening wedge HTOs using two distinct surgical techniques and fixation devices.Methods:Controlled Laboratory Study. Experienced surgeons performed valgus producing opening wedge HTOs in 24 matched paired cadaveric specimens using free hand (FH, n=12) and biplanar cutting jig (Jig, n=12) techniques. Digital fluoroscopy was used to capture anteroposterior and lateral images in all specimens, and the angle of posterior tibial slope (TS) was measured using digital software (NIH image; Bethesda, MD) in a manner blinded for technique and fixation.Results:There was good to excellent intra- and inter-observer reliability with the measurement technique using a Model 3, k, intra-class correlation coefficient (ICC). Both observers’ measurements passed tests for homogeneity (p=0.07, and p=0.12). There was no significant change in the maintenance of tibial slope between JIG and FH groups for observer 1 [JIG = 2.40° (SD = 1.3°) FH= 2.95° (SD=2.89°), p = 0.55] or observer 2 [JIG = 2.32° (SD = 2.5°) FH = 3.14° (SD=3.3°), p = 0.49].Conclusion:When performing a valgus producing opening wedge HTO, neither the cutting jig nor the free hand technique maintained native posterior tibial slope. Both techniques increased posterior tibial slope by an average of 2-3° with no significant difference between the groups. This change in posterior tibial slope is consistent with previously reported values in the literature.

Radiographic Landmarks for Tunnel Positioning in Posterior Cruciate Ligament Reconstructions

Background: Consistent radiographic guidelines for tunnel placement in single- or double-bundle posterior cruciate ligament (PCL) reconstructions are not well defined. Quantitative guidelines reporting the location of the individual PCL bundle attachments would aid in intraoperative tunnel placement and postoperative assessment of a PCL reconstruction. Hypothesis: Consistent and reproducible measurements in relation to radiographic landmarks for the entire PCL and its individual bundle attachments are achievable. Study Design: Controlled laboratory study. Methods: The femoral and tibial PCL bundle attachment centers of 20 nonpaired fresh-frozen cadaveric knees were labeled using radio-opaque spheres and the attachment areas were labeled using barium sulfate. Anteroposterior (AP) and lateral radiographs of the femur and tibia were obtained, and measurements of the distances between the PCL bundle centers and landmarks were acquired. Results: On the AP femur view, the anterolateral bundle (ALB) and posteromedial bundle (PMB) centers were 34.1 ± 3.0 mm and 29.2 ± 3.0 mm lateral to the most medial border of the medial femoral condyle, respectively. The lateral femur images revealed that the ALB center was 17.4 ± 1.7 mm and the PMB center was 23.9 ± 2.7 mm posteroproximal to a line perpendicular to the Blumensaat line that intersected the anterior margin of the medial femoral condyle cortex. Anteroposterior tibia images revealed that the ALB and PMB centers were located 0.2 ± 2.1 mm proximal and 4.9 ± 2.9 mm distal to the proximal joint line, respectively. The PCL attachment center was 1.6 ± 2.5 mm distal to the proximal joint line. On the lateral tibia view, the ALB center was 8.4 ± 1.8 mm, the PCL attachment center was 5.5 ± 1.7 mm, and the PMB center was 2.5 ± 1.5 mm superior to the champagne glass drop-off of the posterior tibia. Conclusion: Radiographic measurements from several clinically relevant views of the femur and tibia were reproducible with regard to the anatomic locations of the ALB and PMB centers. The measurements from the lateral femur and tibia views provided the most clinically pertinent radiographic measurements intraoperatively. Clinical Relevance: This study established a set of clinically relevant radiographic guidelines for anatomic reconstruction of the PCL. The parameters set forth in this study can be used in both the intraoperative and postoperative settings for both single- and double-bundle PCL reconstructions.