Imaging Features Following Breast Explant Surgery: A Pictorial Essay.

Breast implants can be removed with breast explantation surgery (BES) for various reasons, including patient dissatisfaction, capsular contracture, implant infection or rupture, breast implant-associated anaplastic large cell lymphoma, and a recently emerging phenomenon called breast implant illness. There is very limited data on the imaging appearance after BES. A retrospective chart review was performed for patients with BES findings on imaging reports for the period between October 2016 and October 2021. When assessing BES techniques, a key element is determining whether the implant's fibrous capsule requires removal. The second important question is if the patient requires an additional aesthetic procedure after BES. BES techniques include capsulotomy, and partial, total, or en bloc capsulectomy. Adjunctive aesthetic or reconstructive procedures after BES include fat grafting, mastopexy, augmentation, and reconstruction with flaps. The majority of post-BES breast imaging findings are related to the surgical scar/bed, thereby confirming that the type of explantation surgery is important. Imaging findings after BES include focal and global asymmetries, architectural distortions, calcifications, calcified and non-calcified fat necrosis, masses, hematomas, seromas, capsular calcifications, and silicone granulomas. Most importantly, since these patients have residual breast tissue, paying attention to imaging features that are suspicious for breast cancer is necessary.

Pedicle screws with modular head vs. preassembled head used in cortical bone trajectory: Can pars and pedicle fractures be prevented in osteoporotic bone?

Pars and pedicle fractures as a result of CBT (cortical bone trajectory) during pedicle screw placement have been reported. The primary aim of the study is to compare the fracture rate between screws with modular heads to screws with standard pre-assembled tulip heads. The secondary aim of the study is to determine the potential variables that can be identified prior to instrumentation in order to predict risk of fractures. Twenty-four fresh frozen lumbar vertebrae were obtained from five different cadavers. Anatomical landmark measurements were obtained. Right and left pedicles of each vertebra were randomly instrumented with the preassembled head screws (n=24) and modular head screws (n=24) under video recording. X-ray images were obtained for measuring relative angle deviations between tapped and final screw trajectories. Finally, pullout tests were performed. Seventeen out of twenty-four (70.8%) of the spinous processes had to be excised in order to obtain proper trajectories. Six fractures occurred with pre-assembled head screws versus one in the modular head screws (p=0.04). Distances from the midline to the medial wall of the pedicle were marginally significant as a predictor for fracture (p=0.08). The pullout loads between both types of screws were not statistically different (p=0.38). Age was better correlated with pullout load than absolute bone density value (p<0.001). In conclusion, modular head screws had a significantly lower fracture rate than pre-assembled head screws for cortical bone trajectory in osteoporotic bone. There was no clear anatomic variable that could be measured pre-operatively to predict potential fracture risk in CBT.

C1 Lateral Mass Displacement and Transverse Atlantal Ligament Failure in Jefferson's Fracture: A Biomechanical Study of the "Rule of Spence".

BACKGROUND: Jefferson's fracture, first described in 1927, represents a bursting fracture of the C1 ring with lateral displacement of the lateral masses. It has been determined that if the total lateral mass displacement (LMD) exceeds 6.9 mm, there is high likelihood of transverse atlantal ligament (TAL) rupture, and if LMD is less than 5.7 mm TAL injury is unlikely. Several recent radiographic studies have questioned the accuracy and validity of the "rule of Spence" and it lacks biomechanical support. OBJECTIVE: To determine the amount of LMD necessary for TAL failure using modern biomechanical techniques. METHODS: Using a universal material testing machine, cadaveric TALs were stretched laterally until failure. A high-resolution, high-speed camera was utilized to measure the displacement of the lateral masses upon TAL failure. RESULTS: Eleven cadaveric specimens were tested (n = 11). The average LMD upon TAL failure was 3.2 mm (±1.2 mm). The average force required to cause failure of the TAL was 242 N (±82 N). From our data analysis, if LMD exceeds 3.8 mm, there is high probability of TAL failure. CONCLUSION: Our findings suggest that although the rule of Spence is a conceptually valid measure of TAL integrity, TAL failure occurs at a significantly lower value than previously reported (P < .001). Based on our literature review and findings, LMD is not a reliable independent indicator for TAL failure and should be used as an adjunctive tool to magnetic resonance imaging rather an absolute rule.

Rotation effect and anatomic landmark accuracy for midline placement of lumbar artificial disc under fluoroscopy.

PURPOSE: Total disc arthroplasty can be a viable alternative to fusion for degenerative disc disease of the lumbar spine. The correct placement of the prosthesis within 3 mm from midline is critical for optimal function. Intra-operative radiographic error could lead to malposition of the prosthesis. The objective of this study was first to measure the effect of fluoroscopy angle on the placement of prosthesis under fluoroscopy. Secondly, determine the visual accuracy of the placement of artificial discs using different anatomical landmarks (pedicle, waist, endplate, spinous process) under fluoroscopy. METHODS: Artificial discs were implanted into three cadaver specimens at L2-3, L3-4, and L4-L5. Fluoroscopic images were obtained at 0°, 2.5°, 5°, 7.5°, 10°, and 15° from the mid axis. Computerized tomography (CT) scans were obtained after the procedure. Distances were measured from each of the anatomic landmarks to the center of the implant on both fluoroscopy and CT. The difference between fluoroscopy and CT scans was compared to evaluate the position of prosthesis to each anatomic landmark at different angles. RESULTS: The differences between the fluoroscopy to CT measurements from the implant to pedicle was 1.31 mm, p < 0.01; implant to waist was 1.72 mm, p < 0.01; implant to endplate was 1.99 mm, p < 0.01; implant to spinous process was 3.14 mm, p < 0.01. When the fluoroscopy angle was greater than 7.5°, the difference between fluoroscopy and CT measurements was greater than 3 mm for all landmarks. CONCLUSIONS: A fluoroscopy angle of 7.5° or more can lead to implant malposition greater than 3 mm. The pedicle is the most accurate of the anatomic landmarks studied for placement of total artificial discs in the lumbar spine.

Preventing Instrumentation Failure in Three-Column Spinal Osteotomy: Biomechanical Analysis of Rod Configuration.

STUDY DESIGN: Biomechanical analysis. OBJECTIVES: To show the role of additional rods and long-term fatigue strength to prevent the instrumentation failure on three-column osteotomies. SUMMARY OF BACKGROUND DATA: Three-column osteotomy such as pedicle subtraction osteotomy (PSO) and vertebral column resections are surgical correction options for fixed spinal deformity. Posterior fixation for the PSO involves pedicle screw-and rod-based instrumentation, with the rods being contoured to accommodate the accentuated lordosis. Pseudarthrosis and instrumentation failure are known complications of PSO. METHODS: Unilateral pedicle screw and rod constructs were mounted in ultra-high-molecular-weight polyethylene blocks using a vertebrectomy model with the rods contoured to simulate posterior fixation of a PSO. Each construct was cycled under a 200 N load at 5 Hz in simulated flexion and extension to rod failure. Three configurations (n = 5) of titanium alloy rods were tested: single rod (control), double rod, and bridging rod. Outcomes were total cycles to failure and location of rod failure. RESULTS: Double-rod and bridging-rod constructs had a significantly higher number of cycles to failure compared with the single-rod construct (p < .05). Single-rod constructs failed at or near the rod bend apex, whereas the majority of double-rod and bridging-rod constructs failed at the screw-rod or rod-connector junction. CONCLUSIONS: Double-rod and bridging-rod constructs are more resistant to fatigue failure compared with single-rod constructs in PSO instrumentation and could be considered to mitigate the risk of instrumentation failure.

A comparison of Staphylococcus aureus biofilm formation on cobalt-chrome and titanium-alloy spinal implants.

The use of cobalt chrome (CoCr) implants in spinal surgery has become increasingly popular. However, there have been no studies specifically comparing biofilm formation on CoCr with that of titanium-alloy spinal implants. The objective of this study was to compare the difference in propensity for biofilm formation between these two materials, as it specifically relates to spinal rods. Staphylococcus aureus subsp. Aureus (ATCC 6538) were incubated with two different types of spinal rods composed of either CoCr or titanium-alloy. The spinal rods were then subject to a trypsin wash to allow for isolation of the colonized organism and associated biofilms. The associated optical density values (OD) from the bacterial isolates were obtained and the bacterial solutions were plated on brain-heart infusion agar plates and the resultant colony-forming units (CFU) were counted. The OD values for the titanium-alloy rods were 1.105±0.096nm (mean±SD) and 1.040±0.026nm at 48hours and 96hours, respectively. In contrast, the OD values for the CoCr rods were 1.332±0.161nm and 1.115±0.207nm at 48 and 96hours, respectively (p<0.05). The CFU values were 1481±417/100mm(2) and 745±159/100mm(2) at 48 and 96hours, respectively for the titanium-alloy group. These values were significantly lower than the CFU values obtained from the CoCr group which were 2721±605/100mm(2) and 928±88/100mm(2) (p<0.001) at both 48 and 96hours respectively. Our findings, evaluating both the OD and CFU values, indicate that implants composed of CoCr had a higher proclivity towards biofilm formation compared to titanium-alloy implants.

A comparison of open versus percutaneous cervical transfacet fixation.

OBJECTIVE The aim of this study is to describe a technique for percutaneous cervical transfacet screw placement and compare this technique to the open technique with regard to the accuracy of facet capture and the potential of placing neurovascular structures at risk. METHODS Eight cadaveric cervical spines were harvested. One side of each spine was assigned to the percutaneous group, and the other side to the open group. The spines were instrumented from C-3 to T-1 (80 screws). The distance to the spinal canal, foramen transversarium, and neural foramen were measured to determine the likelihood of placing neurovascular structures at risk. The percentage of the facet joint captured and the angle of screw trajectory compared with the ideal trajectory were used to determine the accuracy. RESULTS There were, in total, 11 misplacements of screws: 2 screws using the open technique and 9 screws using the percutaneous technique (p = 0.006). From a neurovascular point of view, 3 percutaneous screws violated the foramen transversarium. Two of these percutaneous screws violated the neural foramen. No neurovascular foramina were violated using the open technique. The open technique resulted in a significantly greater distance from the screw to the spinal canal (p < 0.001). The distance from the screw to the foramen transversarium (p = 0.015), as well as the distance from the screw to the neural foramen (p = 0.012), did not demonstrate statistical difference when using either technique. As for the accuracy of facet capture, 8 screws exhibited less than 15% purchase of the facet joint. Six of these screws were placed using the percutaneous technique, and 2 screws were placed using the open technique. CONCLUSIONS There is a higher incidence of screw misplacement using the percutaneous transfacet in comparison to the open transfacet technique. The accuracies of facet capture using the 2 techniques were not statistically different. Surgeons will need to understand the potential risk of using the percutaneous technique as an alternative to open transfacet fixation.

Survivorship and clinical outcomes after multi-level anterior lumbar reconstruction with stand-alone anterior lumbar interbody fusion or hybrid construct.

In multilevel disc disease, there is still uncertainty regarding whether multiple total disc replacement is more effective and safer than fusion. Our objective was to measure and compare the clinical outcome of multilevel hybrid constructs with stand-alone anterior lumbar interbody fusion (ALIF) using a retrospective analysis. Sixty-four patients with chronic low back pain determined to be from two or three-level degenerative disc disease were included. Thirty-three patients were treated with hybrid fusion and 31 with ALIF. Several parameters were retrospectively reviewed, including blood loss, operation time, hospital stay, Visual Analog Scale (VAS) score, Oswestry Disability Index (ODI), and survivorship without the need for revision surgery. Telephone follow-ups were conducted to ascertain survivorship, clinical outcomes (VAS, ODI) and patient satisfaction. Operation time was longer in the hybrid group (p=0.021). The hybrid group showed a significant improvement in VAS and ODI with 52.2% and 50.0% improvement versus 28.3% and 25.5% in the ALIF group (p<0.05). At the telephone follow-up for patient satisfaction, 95.7% (n=22) of the hybrid group were satisfied and 95.2% (n=21) of the ALIF group were satisfied. Seventy-four percent (n=17) in the hybrid group and 85.7% (n=18) in the ALIF group would choose to do the initial surgery again. Kaplan-Meier analysis showed 80.5% survivorship for hybrids and 75.9% for ALIF at 5years. With our clinical outcomes in VAS and ODI scores, these results, when taken together, indicate that hybrid fusion is a valid and viable alternative to ALIF fusion, with at least equal if not better clinical outcomes in terms of survivorship, back pain, and disability scores.

Pars and pedicle fracture and screw loosening associated with cortical bone trajectory: a case series and proposed mechanism through a cadaveric study.

BACKGROUND CONTEXT: Cortical bone trajectory (CBT) technique for pedicle screw placement in the lumbar spine has become more popular since its introduction in 2009. The distinct advantages of using the CBT technique involve increased screw purchase within the cortical bone and reduced surgical dissection. However, contrary to several favorable biomechanical results, there were anecdotal reports of clinical complications associated with CBT. PURPOSE: This study aimed (1) to report on two unique pars and pedicle fracture cases involving the use of the CBT technique and (2) to perform a cadaveric pilot study to determine the possible mechanism for this fracture pattern. STUDY DESIGN/SETTING: A case report and cadaveric study were carried out. METHODS: After presenting two clinical cases, 19 fresh-frozen lumbar vertebrae were obtained from 8 cadavers. Pedicle screws were instrumented on each level using CBT under video recording. After the instrumentation, X-ray images were obtained, and anatomical dissections were performed. RESULTS: To be able to reach a necessary angle for medial to lateral CBT trajectory, 13 out of 19 (68%) spinous processes had to be removed. There were a total of seven complications. One pars and pedicle fracture out of 37 trajectories (2.7%) and 6 out of 37 trajectory deviations (16.2%), which resulted in gross loosening, were observed. CONCLUSIONS: The head of the pedicle screw impinging on the base of spinous process and lamina was observed in our cadaveric model. This mechanism could potentially explain both screw loosening and fractures associated with the CBT technique.

Novel posterior technique to temporize life-threatening hemorrhage after great vessel laceration during posterior osteotomy.

PURPOSE: Great vessel injury during posterior 3-column osteotomy is rare, but potentially fatal. Literature review revealed limited data guiding spine surgeons during this major catastrophe. In this study our aim was first, to present our case of mortality; second, to discuss a novel technique that can be performed to temporize hemorrhage in a life-threatening situation where an iatrogenic great vessel injury occurs and hemodynamic stability cannot be achieved through usual means of hemostasis; third, a cadaveric study to determine if this novel technique is feasible. METHODS: Three fresh cadavers including thoracic, lumbar, and pelvis were used. A thoraco-abdominal approach was used to access great vessels at the level of L3. The aorta and vena cava were identified and tagged. The cadavers were turned prone; a pedicle subtraction osteotomy was performed at the level of L3. A novel posterior peri-vertebral approach was used to reach the great vessels. The aorta and vena cava were occluded digitally with this approach and success confirmed visually through the thoraco-abdominal incision. Timing of the procedure and structures at risk were recorded. RESULTS: In all three cadavers, we were able to successfully occlude the great vessels from a prone position. The average amount of time it took to digitally occlude the great vessels was less than a minute. Structures at risk included the L1 and L2 nerve roots, lumbosacral plexus, and the sympathetic trunk. CONCLUSIONS: The posterior peri-vertebral approach can potentially be used by a spine surgeon during a life-threatening situation to temporarily occlude great vessel hemorrhage while waiting for the assistance of a vascular/trauma team.

Comparison Between Gearshift And Drill Techniques For Pedicle Screw Placement By Resident Surgeons.

BACKGROUND: Various techniques have been described for pedicle screw placement with established clinical and radiological success. Suboptimal screw trajectories can compromise bony purchase and, worse yet, cause neurological and vascular injuries. Thus, it is of paramount importance to achieve maximum accuracy of screw placement. Our objective is to evaluate the accuracy of pedicle screw placement in the thoracolumbar spine by resident surgeons. Two popular techniques, gearshift versus drill, were compared. METHODS: This is a a cadaveric surgical technique comparison study. Six resident surgeons instrumented the spine from T1 to S1 using both gearshift and drill techniques. Each pedicle was randomly assigned to either of the techniques. Pedicle screws were placed freehand without radiographic guidance. Violations (medial, lateral, anterior, superior and inferior) were recorded by studying the computerized tomographic scans of instrumented cadavers by blinded observers. Critical perforations were defined as greater than 2mm breach of the pedicle wall. RESULTS: A total of 100 vertebrae (200 pedicles) were instrumented in the six cadavers. 103 pedicles were breached (51.5% of total pedicles). Lateral violations were the most encountered (65% of violations, 67 total, 48 critical, 19 noncritical) followed by medial (24%, 25 total, 13 critical, 12 noncritical), and the rest were anterior (3%), superior (4%) and inferior (4%). There was no overall difference in violations comparing the gearshift technique (49.5%, 51 total, 37 critical, 14 noncritical) with drill technique (50.5%, 52 total, 33 critical, 19 noncritical). Analyzing the breaches at individual vertebra indicated most violations at T6 (11), T5 (10), followed by T3 (9) and T4 (9), decreasing towards the lumbosacral vertebrae. CONCLUSION: The results of this study suggest that the gearshift and drill techniques for placement of pedicle screws in the thoracolumbar spine fare similarly with regards to risk of breach when applied by resident surgeons.

MRI evaluation of the knee with non-ferromagnetic external fixators: cadaveric knee model.

INTRODUCTION: The advent of MRI-compatible external fixation devices has made the use of MRI possible in patients who have been treated with external fixation. However, although there have been multiple studies determining the safety of MRI scans with external fixator devices, there are no studies determining the artifact effect these devices can have on the MRI image. The purpose of our study was to evaluate the effect of two popular brands (Stryker and Synthes) of MRI-compatible external fixators on the diagnostic capacity of a knee MRI. We hypothesize that (1) MRI images would have higher noise due to the presence of an external fixator and (2) images of high diagnostic capacity will be obtainable in the presence of each external fixator spanning the knee. METHODS: Using seven cadaveric knees, a study was performed to analyze MRI images taken in the presence each external fixator. Scans taken with no external fixator present served as controls. Signal-to-noise ratios (SNRs) were measured at five anatomic structures. These structures were compared as a quantitative measure of image quality. A qualitative analysis was also performed using a five-point grading scale to assess the influence of metal artifact on the quality of the images. Each scan was graded by three blinded musculoskeletal radiologists focusing on six key anatomic structures. RESULTS: A reduction in SNR was identified on the external fixator group compare to the control groups at the patella tendon, MM and PCL. Qualitative scoring by three expert radiologists showed no difference in ability to identify the six key anatomic landmarks between the Stryker, Synthes and control images. CONCLUSION: Although the presence of external fixation devices does increase the noise artifact in MRI scans, patients treated with these external fixators can undergo MRI of local structures with high likelihood of obtaining diagnostic quality images.

Treatment of os odontoideum in a patient with spastic quadriplegic cerebral palsy.

Severe atlantoaxial instability due to os odontoideum in a patient with spastic cerebral palsy has not been well described. There is no consensus on treatment, particularly with regard to conservative or surgical options. Our patient was a 9-year-old girl with spastic cerebral palsy and unstable os odontoideum as an incidental finding. During the waiting period for elective surgical treatment, the patient developed respiratory compromise. Surgery was performed to reduce the subluxation and for C1-C2 arthrodesis and the girl regained baseline respiratory function. A CT scan was obtained 1 year after the initial surgery and revealed adequate maintenance of reduction and patency of the spinal canal. This patient highlights the fact that unstable os odontoideum can cause mortality due to respiratory distress in patients with spastic cerebral palsy. This is an important factor in deciding treatment options for cerebral palsy patients with low functional demand. We review the relevant literature.

Reason for Lawsuit in Spinal Cord Injury Affects Final Outcome.

STUDY DESIGN: Retrospective cohort study. OBJECTIVE: To review past cases and analyze them to determine whether reason for lawsuit led to a defense versus plaintiff verdict when patients sustain spinal cord injury. Secondary objectives included analyzing demographic factors and monetary awards for plaintiff verdicts and settlements. SUMMARY OF BACKGROUND DATA: Evaluating malpractice cases could provide valuable information for the physician who has been sued by a patient. Previous studies about litigation and spine have been focused on medical tort reform and not on the reasons for litigation and lawsuit outcome. METHODS: A large national medicolegal research service for civil and criminal court called "VerdictSearch" was queried for "spinal cord injury" between the years 2000 and 2010. Reason for lawsuit separated into 2 groups, error in diagnosis (n = 48), and error in treatment (n = 25). The anatomical region, outcome, cost, and job for sued health care workers recorded for each lawsuit. RESULTS: Compared with physicians who were sued for errors in diagnosis, those sued for an error of treatment had a relative risk of 2.69 (95% confidence interval, 1.40-5.16) to receive a defense verdict (P = 0.003). There were no significant differences in demographic information, including age, sex, occupation type, and level of injury. Among specialties, surgeons had the highest number of suits. The median value for each anatomic area was highest in thoracic spine ($1.90 million), followed by cervical spine ($1.80 million) and lumbar spine ($0.750 million), although there were no statistical differences between the 3 areas (P = 0.301). The median monetary award for a plaintiff verdict was higher than that for a settlement ($2.90 million, interquartile range: 1.50-12.5 million vs. $1.45 million, interquartile range: 1.00-2.90 million, P = 0.008). CONCLUSION: Physicians are more likely to successfully defend a lawsuit for an error in treatment than for an error in diagnosis. The key to increase the success of defending a lawsuit in regard to spinal cord injury is to avoid delayed and incorrect diagnosis. LEVEL OF EVIDENCE: N/A.

Hoffmann sign: clinical correlation of neurological imaging findings in the cervical spine and brain.

STUDY DESIGN: Retrospective validity study. OBJECTIVE: To investigate the relationship between Hoffmann sign and radiographical evidence of cervical spinal cord compression and brain lesions. SUMMARY OF BACKGROUND DATA: Clinical significance of Hoffmann sign remains controversial with conflicting reports regarding its sensitivity and specificity and its usefulness. METHODS: Patients were divided into 2 groups according to the presence of Hoffmann sign on physical examination. Imaging studies were blindly examined by 2 observers for possible cervical and brain lesions. The sensitivity, specificity, positive predictive value, negative predictive value, as well as accuracy for Hoffmann sign as it relates to cervical spinal cord compression and brain pathology, were calculated. RESULTS: Of the 91 patients with a positive Hoffmann sign, 32 (35%) showed severe cervical cord compression and/or myelomalacia. Forty-seven of these patients had brain imaging studies, and 5 (10%) had positive findings. There were 80 patients in the negative Hoffmann sign or control group. Twenty-one (27%) of them had severe cervical cord compression and/or myelomalacia. Twenty-three of these control patients underwent neurological imaging of the brain, and 2 (8%) had positive findings. Hoffmann sign was found to have 59% sensitivity, 49% specificity, 35% positive predictive value, and 72% negative predictive value for cervical cord compression. For brain pathology, sensitivity was 71%, specificity 33%, positive predictive value 10%, and negative predictive value 95%. CONCLUSION: Hoffmann sign has too low a positive predictive value to be relied upon as a stand-alone physical examination finding and is not a reliable screening tool for solely predicting the presence of cervical spinal cord compression or brain pathology. LEVEL OF EVIDENCE: 2.