Prior Fixation Research Articles

Prior surgical fixation of proximal humerus fractures is associated with increased complications following subsequent reverse shoulder arthroplasty

BackgroundThe objective of this study was to compare complication rates between patients undergoing reverse shoulder arthroplasty (RSA) after a prior open reduction and internal fixation (ORIF) for proximal humerus fracture (PHF) to those undergoing RSA as a primary treatment for PHFs, glenohumeral osteoarthritis, or rotator cuff tear arthropathy (CTA). MethodsPatients who underwent RSA between 2015 and 2020 were identified in the Mariner database. Patients were separated into 3 mutually exclusive groups: (1) RSA for osteoarthritis, rotator cuff tear, or CTA (Control-RSA); (2) RSA as a primary treatment for PHF (PHF-RSA); and (3) RSA for patients with prior ORIF of PHFs (ORIF-RSA). Ninety-day medical and 2-year postoperative surgical complications were identified. In addition, patients in the PHF-RSA group were subdivided into those undergoing RSA for PHF within 3 months of the fracture (acute) vs. those treated greater than 3 months from diagnosis (delayed). Multivariate regression was performed to control for differences in comorbidities and demographics. ResultsA total of 30,824 patients underwent primary RSA for arthritis or CTA, 5389 patients underwent RSA as a primary treatment for a PHF, and 361 patients underwent RSA after ORIF of a PHF. ORIF before RSA was associated with an increased risk of overall revision (odds ratio [OR] 2.45, P = .002), infection (OR 2.40, P < .001), instability (OR 2.43, P < .001), fracture (OR 3.24, P = .001), minor medical complications (OR 1.59, P = .008), and readmission (OR 2.55, P = .001) compared with the Control-RSA cohort. RSA as a primary treatment for PHF was associated with an increased risk of 2-year revision (OR 1.60, P < .001), infection (OR 1.51, P < .001), instability (OR 2.84, P < .001), and fracture (OR 2.54, P < .001) in addition to major medical complications (OR 2.02, P < .001), minor medical complications (OR 1.92, P < .001), 90-day emergency department visits (OR 1.26, P < .001) and 90-day readmission (OR 2.03, P < .001) compared with the Control-RSA cohort. The ORIF-RSA group had an increased risk of periprosthetic infection (OR 1.94, P = .002) when compared with the PHF-RSA cohort. There were no differences in medical or surgical complications in the RSA-PHF cohort between patients treated in an acute or delayed fashion. ConclusionRSA following ORIF of a PHF is associated with increased complications compared with patients undergoing RSA for nonfracture indications. Prior ORIF of a PHF is also an independent risk factor for postoperative infection after RSA compared with patients who undergo RSA as a primary operation for fracture. The timing of RSA as a primary operation for PHF does not appear to impact the rates of postoperative medical and surgical complications.

Poster 256: The "N+10 Rule" to Avoid Graft Tunnel Mismatch in Bone-Patellar Tendon-Bone Anterior Cruciate Ligament Reconstruction Using Independent Femoral Tunnel Drilling

Objectives: To determine the amount of tibial graft tunnel mismatch during application of the “N+10” rule in arthroscopic assisted anterior cruciate ligament (ACL) reconstruction with bone-patellar tendon-bone (BTB) graft using independent femoral tunnel drilling.To compare actual (measured) tibial tunnel length and desired (calculated) tibial tunnel length when using the “N+10” rule for independent femoral tunnel drilling. Methods:Twenty paired knees from 10 fresh frozen cadaveric specimens (5 female and 5 male specimens) underwent arthroscopic assisted bone-patellar tendon-bone ACL reconstruction using independent femoral tunnel drilling with either a hyperflexion accessory anteromedial portal (n=10) or flexible reamer technique (n=10). The prepared patellar tendon graft bone blocks were trimmed to 10 x 20mm for all specimens and the intertendinous distance (N) between the bone blocks was measured. The “N+10 Rule” was used to set the angle of the ACL tibial tunnel guide to the appropriate degree setting for drilling. The amount of excursion or recession of the tibial bone plug in relation to the anterior tibial cortical aperture was measured in both flexion and extension. A +/-6mm threshold was used to assess this strategy based on prior biomechanical aperture fixation studies. As a secondary outcome, the intraarticular distance (IAD) and the actual tibial tunnel length (TTL) were measured and compared to the planned TTL based on the equation: IAD + TTL = N + 20 (size of bone plug in millimeters)Results:The average BTB ACL intertendinous distance (N) was 47.5mm (SD =5.5mm). The average measured IAD was 27.2mm (SD=3.0mm). Using the “N+10 Rule”, the average mismatch of the tibial tunnel was 4.9mm (SD=3.6mm) and 3.8mm (SD=3.5mm) in flexion and extension, respectively. Both values fall within the +/- 6mm threshold. When comparing the actual measured tibial tunnel length (TTL) to the desired TTL, there was an average difference of 5.4mm (SD=3.9mm)Conclusions:The “N+10” rule resulted in an acceptable average mismatch in both flexion and extension using the threshold of +/- 6mm for 20 cadaveric knees. Measured actual TTL compared to the desired calculated TTL were acceptable 61% of the time using the same threshold. The “N+10” is a simple and effective intraoperative strategy for achieving desired tibial tunnel length to avoid excessive graft tunnel mismatch.Figure 1:Derived formula for calculating ideal tibial tunnel length (TTL) using intraarticular distance (IAD), and the known values of the intertendinous distance (N) and lengths of the bone blocks (20mm).Figure 2:Intraoperative photo of BTB ACL graft measuring intertendinous distance between the bone plugs (N=55mm). Following the "N+10" ruleFigure 3:Intraoperative photo of tibial ACL guide measurement of tibial tunnel length at 50mm with guide set to 65 degrees.Figure 4:Intraoperative photo of the ACL tibial tunnel guide positioned on the anatomic tibial footprint set to 65 degrees (N=55mm). Using this setting for the guide, the tibial tunnel measured 50mm as seen in the zoomed in photo, as per the formula.

A combination of scanning electron microscopy and broad argon ion beam milling provides intact structure of secondary tissues in woody plants

The secondary tissues of woody plants consist of fragile cells and rigid cell walls. However, the structures are easily damaged during mechanical cross-sectioning for electron microscopy analysis. Broad argon ion beam (BIB) milling is commonly employed for scanning electron microscopy (SEM) of hard materials to generate a large and distortion-free cross-section. However, BIB milling has rarely been used in plant science. In the present study, SEM combined with BIB milling was validated as an accurate tool for structural observation of secondary woody tissues of two samples, living pine (Pinus densiflora) and high-density oak wood (Quercus phillyraeoides), and compared with classical microtome cross-sectioning. The BIB milling method does not require epoxy resin embedding because of prior chemical fixation and critical point drying of the sample, thus producing a three-dimensional image. The results showed that xylem structures were well-preserved in their natural state in the BIB-milled cross-section compared with the microtome cross-section. The observations using SEM combined with BIB milling were useful for wide-area imaging of both hard and soft plant tissues, which are difficult to observe with transmitted electron microscopy because it is difficult to obtain sections of such tissues, particularly those of fragile reaction woods.

Risk of Dislocation and Revision Following Primary Total Hip Arthroplasty in Patients With Prior Lumbar Fusion With Spinopelvic Fixation

BackgroundThe effect of spinopelvic fixation in addition to lumbar spinal fusion (LSF) on dislocation/instability and revision in patients undergoing primary total hip arthroplasty (THA) has not been reported previously. MethodsThe PearlDiver Research Program was used to identify patients aged 30 and above undergoing primary THA who received (1) THA only, (2) THA with prior single-level LSF, (3) THA with prior 2-5 level LSF, or (4) THA with prior LSF with spinopelvic fixation. The incidence of THA revision and dislocation/instability was compared through logistic regression and Chi-squared analysis. All regressions were controlled for age, gender, and Elixhauser Comorbidity Index (ECI). ResultsBetween 2010 and 2018, 465,558 patients without history of LSF undergoing THA were examined and compared to 180 THA patients with prior spinopelvic fixation, 5,299 with prior single-level LSF, and 1,465 with prior 2-5 level LSF. At 2 years, 7.8% of THA patients with prior spinopelvic fixation, 4.7% of THA patients with prior 2-5 level LSF, 4.2% of THA patients with prior single-level LSF, and 2.2% of THA patients undergoing only THA had a dislocation event or instability (P < .0001). After controlling for length of fusion, pelvic fixation itself was associated with higher independent risk of revision (at 2 years: 2-5 level LSF + spinopelvic fixation: aHR = 3.15, 95% CI 1.77-5.61, P < .0001 vs 2-5 level LSF with no spinopelvic fixation: aOR = 1.39, 95% CI 1.10-1.76, P < .0001). ConclusionAt 2 years, spinopelvic fixation in THA patients were associated with a greater than 3.5-fold increase in hip dislocation risk compared to those without LSF, and an over 2-fold increase in THA revision risk compared to those with LSF without spinopelvic fixation. Level of EvidenceIII.

Surgical Treatment and Outcomes of Adjacent Segmental Disease by Additional Extension-fixation Decompression and Fusion without Removing Prior Fixation by Using Domino Connector

Purpose: Adjacent segmental disease (ASDis) represents symptomatic adjacent segment degeneration causing pain or neurological deficit. Revision lumbar decompression and extended spinal fusion remain the surgical gold standard. The surgical technique removes all prior implants (pedicle screw and rods) and applies the new implant to previous surgical sites while extending fixation across adjacent segments with fusion; however, it leads to soft tissue trauma, massive blood loss, prolonged operative time, and an increased fixation cost. This study aimed to present the use of a domino connector for connecting the old rod and new rod for extension fixation without removing prior fixation as an alternative technique. Methods: This study retrospectively analyzed the data of 14 patients with ASDis who underwent revision surgery with the use of a domino connector for connecting the old rod and new rod for extension fixation without the removal of prior fixation. Results: All the patients were aged 59–85 years with a mean age of 67.2 years. The mean duration of ASDis was 4.38 years postoperatively. The patients were grouped according to the modified MacNab criteria as follows: no patient in the excellent group, 12 patients in the good group, and two patients in the fair group. Conclusions: This surgical technique for treating failed back surgery syndrome reduces the extent of the surgery by employing rod connectors without prior instrument revision. It can serve as an alternative for the operative technique for treating patients with ASDis.

Measuring Orthopedic Plate Strain to Track Bone Healing Using a Fluidic Sensor Read via Plain Radiography.

We describe a fluidic X-ray visualized strain indicator under applied load (X-VISUAL) to quantify orthopedic plate strain and inform rehabilitative care. The sensor comprises a polymeric device with a fluidic reservoir filled with a radio-dense fluid (cesium acetate) and an adjoining capillary wherein the liquid level is measured. A stainless-steel lever attaches to the plate and presses upon the acrylic bulb with a displacement proportional to plate bending strain. The sensor was attached to a plate in a Sawbones composite tibia mimic and a human cadaveric tibia. An osteotomy model (5 mm gap) was used to simulate an unstable fracture, and allograft repair to simulate a stiffer healed fracture. The cadaveric and Sawbones tibia were cyclically loaded five times (0-400 N) using a mechanical test stand, and fluid displacement was measured from plain radiographs. The sensor displayed reversible and repeatable behavior with a slope of 0.096 mm/kg and fluid level noise of 50-80 micrometer (equivalent to 5-10 N). The allograft-repaired composite fracture was 13 times stiffer than the unstable fracture. An analysis of prior external fracture fixation studies and fatigue curves for internal plates indicates that the threshold for safe weight bearing should be 1/5th-1/10th of the initial bending for an unstable fracture. The precision of our device (<2% body weight) should thus be sufficient to track fracture healing from unstable through safe weight bearing. The X-VISUAL fluidic sensor enables orthopedic plate strain quantification to monitor facture healing via X-ray imaging.

The Functional Visual Field(s) in simple visual search

During a visual search for a target among distractors, observers do not fixate every location in the search array. Rather processing is thought to occur within a Functional Visual Field (FVF) surrounding each fixation. We argue that there are three questions that can be asked at each fixation and that these imply three different senses of the FVF. 1) Can I identify what is at location XY? This defines a resolution FVF. 2) To what shall I attend during this fixation? This defines an Attentional FVF. 3) Where should I fixate next? This defines an Exploratory FVF. We examine FVFs 2&3 using eye movements in visual search. In three Experiments, we collected eye movements during visual search for the target letter T among distractor letter Ls (Exps 1 and 3) or for a color X orientation conjunction (Exp 2). Saccades that do not go to the target can be used to define the Exploratory FVF. The saccade that goes to the target can be used to define the Attentional FVF since the target was probably covertly detected during the prior fixation. The Exploratory FVF is larger than the Attentional FVF for all three experiments. Interestingly, the probability that the next saccade would go to the target was always well below 1.0, even when the current fixation was close to the target and well within any reasonable estimate of the FVF. Measuring search-based Exploratory and Attentional FVFs sheds light on how we can miss clearly visible targets.

Risk Factors for Distal Radius Osteotomy Nonunion.

Osteotomy-site nonunion after distal radius corrective osteotomy is a detrimental complication. This retrospective study aims to identify patient and surgical factors associated with nonunion risk to help mitigate this. The authors hypothesize that patient factors and potentially modifiable surgical factors are contributory. Thirty-three patients who underwent corrective osteotomy of the distal radius for prior fracture malunion were identified. Radiographs and patient records were reviewed for demographics, comorbidities, nutritional status, plate position, angle and length of osteotomy correction, and graft used. The primary study outcome was osteotomy nonunion. Descriptive and bivariate statistics were used to identify covariates relevant to nonunion. Backward, stepwise logistic regression was applied to investigate the multivariate effects on outcome, and regression analysis was adjusted for confounders. Seven patients (21 percent) experienced nonunion after initial corrective osteotomy. Risk factors associated with nonunion included correction length of osteotomy of 5 mm or greater and prior treatment with open reduction and internal fixation. Autograft use was protective against nonunion. History of osteoporosis showed a trend toward increased risk. Angle of osteotomy correction, nutritional deficit, age, diabetes, smoking status, and obesity were not identified as risk factors by the multivariate model. Distraction length at the osteotomy site, graft selection, and prior internal fixation were significant risk factors for distal radius osteotomy nonunion, but other factors traditionally associated with nonunion did not appear to impact risk. The authors recommend using autograft bone augmentation, particularly when distracting the osteotomy beyond 5 mm or after prior internal fixation. Risk, III.

Is implant sonication useful when screening for infection in conversion of prior hip fracture fixation to total hip arthroplasty?

ObjectiveTo examine sonication results in presumed aseptic conversion total hip arthroplasty (THA) after hip fracture fixation and to evaluate its implications on the treatment outcome.MethodsThis retrospective cohort study reviewed the data from presumed aseptic patients that underwent conversion of prior internal fixation of proximal femoral fractures to THA between 2012 and 2018. Microbiological analysis was performed using sonication of osteosynthesis material and tissue samples. Treatment outcome including the occurrence of periprosthetic joint infection (PJI) was recorded.ResultsA total of 32 patients were included in the study. Of these, five patients (15.6%) had positive intraoperative cultures. The mean follow-up following conversion THA was 43.0 months (range, 19.0–91.5 months). Sonication was positive in three patients (9.4%), all of whom were deemed contaminated and did not develop PJI. Tissue cultures were positive in two patients (6.3%). One patient with Enterococcus faecalis received antibiotic treatment and did not develop PJI. Another patient with growth of Cutibacterium acnes that was initially classified as a contaminant later developed acute PJI caused by the same pathogen. Overall, PJI occurred in two patients (6.3%) after conversion THA.ConclusionSonication of internal fixation devices did not add diagnostic value in clinically aseptic conversion THA. Further studies are needed to better understand the relevance of unexpected positive cultures, and to develop diagnostic criteria for the management of these patients.

Single-stage total hip arthroplasty after failed fixation of proximal femoral fractures: an increased risk for periprosthetic joint infections?

BackgroundHigher complication rates have been reported for total hip arthroplasty (THA) after osteosynthesis of proximal femur fractures (PFF). This study evaluated the infection risk for conversion of internal fixation of PFF to THA by a single-staged procedure in the absence of clear infection signs.MethodsPatients undergoing a one-staged conversion to THA (2013–2018) after prior internal fixation of the proximal femur were included. Preoperative diagnostics with laboratory results, hip aspirations as well as intraoperative microbiology and sonication were assessed. Postoperative complications were recorded as well as patient demographics, duration between initial and conversion to THA, explanted osteosynthesis and implanted THA.ResultsFifty-eight patients (24 male/34 female, 62.8 ± 14.5 years) were included with a mean time of 3.8 ± 7.5 years between internal fixation and conversion to THA (45 cementless, 3 cemented, 3 hybrid and 7 hybrid inverse THAs). Preoperative mean blood level CRP was 8.36 ± 14 mg/l (reference value < 5 mg/l) and leukocyte count was 7.11 ± 1.84^3/µl (4.5–10.000^3/µl). Fifty patients had intraoperative microbiological diagnostics, with either swabs in 86.2% and/or sonication in 29.3%. Positive microbiological results were recorded in 10% (5 of 50 patients), with pathogens identified being mainly Staphylococcus. Complications after conversion occurred in 9.6% including a postoperative low-grade infection rate of 5.8% after a mean of 2.5 years.ConclusionThis study found a positive microbiological test result in 10% of a one-stage conversion of PFF fixation to THA. Moreover, we found a high infection rate (5.8%) for early postoperative periprosthetic joint infection. Interestingly, CRP has not been proven to be an adequate parameter for low-grade infections or occult colonized implants. Therefore, we recommend a comprehensive pre- and intraoperative diagnostic including hip aspiration, swabs and sonication when considering one-staged revision.

Contact Pneumatic Ureterolithotripsy Using LMA StoneBreaker Lithotriptor and Search for Opportunities to Increase Effectiveness

The objective: to evaluate the effectiveness of portable pneumatic contact lithotripter LMA StoneBreaker in endoscopic contact ureterolithotripsy of ureteral stones of different localization depending on their density and search for opportunities to increase it. Materials and methods. Contact pneumatic ureterolithotripsy was performed in 89 patients (49 men, 40 women), 39 (43.8%) patients (I group) underwent standard contact pneumoureterolithotripsy, and 50 (56.2%) patients (11 group) – modified (with prior fixation of the stone in the ureter loop Dormia), which allowed urethrolithotripsy in situ and prevented the migration of stones and their fragments proximally. The number of strokes required to initiate fragmentation, complete fragmentation, and total ureterolithotripcy time for stones of different localization and density were determined. The integrity of the stones was determined by computed tomography in units of Haunsfield (HU). The mineral composition of stone fragments after their removal was diagnosed by X-ray diffraction analysis. The effectiveness of the applied methods was evaluated in groups of patients by complete (100%) removal of stone fragments from the ureter and by the number of cases of retrograde migration of stones into the renal cavity. Results. No intraoperative complications were observed. The number of strokes for the initial and complete disintegration of the stone, regardless of the method of ureterolithotripsy and their localization, depended on their density, ie its mineral composition. The minimum number of strokes for start and complete fragmentation of the stone was recorded in patients with a stone density of 480+54 HU and diagnosed as phosphates. Oxalate and uric acid stones, as well as their combinations (density 1310–1580 HU) required the maximum number of blows. Stone migration was noted in 8 (8.99%) patients. Thanks to intraoperative stone fixation was able to reduce the average time of lithotripsy (from 15,65±6.9 min to 12.3±6,15 min) and reduce the frequency of retrograde stone migration from 15.4% (in 6 patients of group 1) to 4% (2 patients of ІI group). The dependence of lithotripsy efficiency on stone localization is established. It was highest in patients with stones of the lower third of the ureter (95% in patients of group 1 and 100% of patients in group II) and with low density (480–840 HU). The lowest efficacy was observed in patients whose stones were localized in the upper third of the ureter (66.3% in group I and 90% in group II) and had a high density (more than 1200 HU). Due to the fixation of the stone with modified pneumoureterolithotripsy, the overall effectiveness of the method increased from 84.6% to 96%. Conclusions. Traneurethral contact pneumoureterolithotrysis using a portable pneumatic lithotripter LMA Stonebreaker – is effective, safe, minimally costly and easy to use. The effectiveness of contact pneumatic ureterolithotripsy depends on the location and density of the stone. The number of strokes required for the initial and complete fragmentation of the stone directly depends on the density of the stone and does not depend on its location and method of performing pneumoureterolithotripsy. The use of a modified technique with fixation of the stone in the ureter during the process of lithotripsy reduces the time of the operation and increases its effectiveness.

Risk of Total Hip Arthroplasty After Acetabular Fracture Fixation: The Importance of Age

BackgroundGeriatric patients are the most rapidly growing cohort of patients sustaining acetabular fractures (AFs). The purpose of this study was to examine the risk of a secondary total hip arthroplasty (THA) in older patients (>60 year old) with a prior AF open reduction internal fixation (ORIF) compared with younger patients (<60 year old) with an AF ORIF on a large population level. MethodsUsing administrative health care data from 1996 to 2010 inclusive of all 202 hospitals in Ontario, Canada, all adult patients with an AF ORIF and a minimum of two year follow-up were identified and included. The risk of THA was examined using a Cox proportional hazards model adjusting for patient risk factors. Secondary outcomes included surgical complications and all-cause mortality. ResultsA total of 1725 patients had an AF ORIF; 1452 (84.2%, mean age of 38.3 ± 12.1 years) aged <60 years (“younger”) and 273 (15.8%, mean age of 69.9 ± 7.8 years) > 60 years (“older”). The mean (SD) follow-up time for all patients was 6.9 (4.2) years. In older patients, 19.4% (53 of 273) went on to receive a secondary THA with a median time to event of 3.9 years, compared with 12.9% (187 of 1452) in the younger patient cohort with a median time of 6.9 years (HR 1.7, 95% CI: 1.2-2.3). As expected, older patients had a higher 90-day mortality rate compared with younger patients (7.7% vs. 0.7%, respectively; HR 9.2, 95% CI: 4.3-19.9; P < .001). ConclusionOlder patients with an AF ORIF are at a significantly higher risk for a secondary THA than younger patients with an AF ORIF.

USP42 protects ZNRF3/RNF43 from R-spondin-dependent clearance and inhibits Wnt signalling.

The tumour suppressors RNF43 and ZNRF3 play a central role in development and tissue homeostasis by promoting the turnover of the Wnt receptors LRP6 and Frizzled (FZD). The stem cell growth factor R‐spondin induces auto‐ubiquitination and membrane clearance of ZNRF3/RNF43 to promote Wnt signalling. However, the deubiquitinase stabilising ZNRF3/RNF43 at the plasma membrane remains unknown. Here, we show that the USP42 antagonises R‐spondin by protecting ZNRF3/RNF43 from ubiquitin‐dependent clearance. USP42 binds to the Dishevelled interacting region (DIR) of ZNRF3 and stalls the R‐spondin‐LGR4‐ZNRF3 ternary complex by deubiquitinating ZNRF3. Accordingly, USP42 increases the turnover of LRP6 and Frizzled (FZD) receptors and inhibits Wnt signalling. Furthermore, we show that USP42 functions as a roadblock for paracrine Wnt signalling in colon cancer cells and mouse small intestinal organoids. We provide new mechanistic insights into the regulation R‐spondin and conclude that USP42 is crucial for ZNRF3/RNF43 stabilisation at the cell surface.

3′ MACE RNA-sequencing allows for transcriptome profiling in human tissue samples after long-term storage

AbstractThis study aims to compare the potential of standard RNA-sequencing (RNA-Seq) and 3′ massive analysis of c-DNA ends (MACE) RNA-sequencing for the analysis of fresh tissue and describes transcriptome profiling of formalin-fixed paraffin-embedded (FFPE) archival human samples by MACE. To compare MACE to standard RNA-Seq on fresh tissue, four healthy conjunctiva from four subjects were collected during vitreoretinal surgery, halved and immediately transferred to RNA lysis buffer without prior fixation and then processed for either standard RNA-Seq or MACE RNA-Seq analysis. To assess the impact of FFPE preparation on MACE, a third part was fixed in formalin and processed for paraffin embedding, and its transcriptional profile was compared with the unfixed specimens analyzed by MACE. To investigate the impact of FFPE storage time on MACE results, 24 FFPE-treated conjunctival samples from 24 patients were analyzed as well. Nineteen thousand six hundred fifty-nine transcribed genes were detected by both MACE and standard RNA-Seq on fresh tissue, while 3251 and 2213 transcripts were identified explicitly by MACE or RNA-Seq, respectively. Standard RNA-Seq tended to yield longer detected transcripts more often than MACE technology despite normalization, indicating that the MACE technology is less susceptible to a length bias. FFPE processing revealed negligible effects on MACE sequencing results. Several quality-control measurements showed that long-term storage in paraffin did not decrease the diversity of MACE libraries. We noted a nonlinear relation between storage time and the number of raw reads with an accelerated decrease within the first 1000 days in paraffin, while the numbers remained relatively stable in older samples. Interestingly, the number of transcribed genes detected was independent on FFPE storage time. RNA of sufficient quality and quantity can be extracted from FFPE samples to obtain comprehensive transcriptome profiling using MACE technology. We thus present MACE as a novel opportunity for utilizing FFPE samples stored in histological archives.RNA of sufficient quality and quantity can be extracted from formalin-fixed paraffin-embedded (FFPE) samples to obtain comprehensive transcriptome profiling using the 3′ massive analysis of c-DNA ends (MACE) RNA-sequencing technology. Thus, MACE provides an opportunity for utilizing FFPE samples stored in histological archives.

Fixing Attached Cells for Staining.

For cell staining, fixation methods decrease generally into two classes, organic solvents and cross-linking reagents. Organic solvents such as alcohols and acetone remove lipids and dehydrate the cells, precipitating the proteins on the cellular architecture. Cross-linking reagents such as paraformaldehyde form intermolecular bridges, normally through free amino groups, thus creating a network of linked antigens. Choosing between fixation in organic solvents or cross-linking agents is empirical. There are no general rules to decide between the two and both procedures are described here. Both methods may denature protein antigens, and for this reason, antibodies prepared against denatured proteins may be more useful for cell staining. In some instances, anti-denatured-protein antibodies are the only ones that can work. Fixation in protein cross-linking reagents such as paraformaldehyde or glutaraldehyde preserves cell structure better than organic solvents but may reduce the antigenicity of some cell components. Simple fixation with paraformaldehyde or glutaraldehyde does not allow the antibody to access the specimen and therefore is followed by a permeabilization step using an organic solvent or nonionic detergent. Using the organic solvent is easy, but it can destroy certain elements of the cell architecture, although prior fixation with paraformaldehyde does help to preserve the cellular structure. If preservation of cell structure is important, the best first choice would be to use a nonionic detergent.

Outcomes of Total Hip Arthroplasty for Healed Intertrochanteric Hip Fractures. A Matched Retrospective Cohort Study

BackgroundMany studies have analyzed the outcomes of total hip arthroplasty (THA) after failed intertrochanteric fracture fixation, but not after healed fracture. The objective is to investigate the influence of a prior healed intertrochanteric fracture fixation on the outcomes of a subsequent THA for osteoarthritis. MethodsThis is a matched retrospective cohort study of THA between 43 patients who suffered a prior intertrochanteric fracture successfully managed with internal fixation and 43 patients without prior hip fracture. Mean age was 73.6 vs 74.2 years. A conventional cementless THA was used in both groups. Functional outcome was assessed by the Harris hip score (HHS) and reduced Western Ontario and McMaster Universities Osteoarthritis Index questionnaire. Radiological assessment was also performed. ResultsMean follow-up was 6.6 (range, 5-8) years. The mean operative time and blood transfusion rate were significantly higher in the fracture group (P = .001), but there was no significant difference in the length of stay. HHS significantly improved in both groups. At final follow-up, HHS was significantly higher in nonfracture group (P = .008), but the rate of patients with excellent and good outcomes was similar (P = .616). Western Ontario and McMaster Universities Osteoarthritis Index score at the final follow-up was not different between groups (P = .058). Complication rate was similar between groups. There were no revisions, dislocations, or loose implants in the study group. ConclusionCementless THA provided successful functional outcomes and implant durability at medium term in patients treated for osteoarthritis following healed intertrochanteric fracture fixation, comparable to those without prior fracture who underwent primary THA. Surgical complexity and complication rate were low.

Scanning Electron Microscopy Study of Retrieved Implants Suggests a Ratcheting Mechanism Behind Medial Migration in Cephalomedullary Nailing of Hip Fractures.

Introduction:Medial migration is the paradoxical migration of the femoral neck element (FNE) superomedially against gravity with respect to the intramedullary component of the cephalomedullary device, increasingly seen in the management of pertrochanteric hip fractures with the intramedullary nail. We postulate that the peculiar anti-gravity movement of the FNE in the medial migration phenomenon stems from a ratcheting mechanism at the intramedullary nail-FNE interface, which should inadvertently produce unique wear patterns on the FNE that can be seen with high-powered microscopy. By examining the wear patterns on retrieved implants from patients with medial migration, our study aims to draw clinical correlations to the ratcheting mechanism hypothesis.Material and Methods:Four FNEs were retrieved from revision surgeries of four patients with prior intramedullary nail fixation of their pertrochanteric hip fractures complicated by femoral head perforation. The FNEs were divided into two groups based on whether or not there was radiographic evidence of medial migration prior to the revisions. Wear patterns on the FNEs were then assessed using both scanning electron microscopy and light microscopy.Results:Repetitive, linearly-arranged, regularly-spaced, unique transverse scratch marks were found only in the group with medial migration, corresponding to the specific segment of the FNE that passed through the intramedullary component of the PFNA during medial migration. These scratch marks were absent in the group without medial migration.Conclusion:Our findings are in support of a ratcheting mechanism behind the medial migration phenomenon with repetitive toggling at the intramedullary nail-FNE interface and progressive propagation of the FNE against gravity.

Return sweeps in reading: Processing implications of undersweep-fixations

Models of eye-movement control during reading focus on reading single lines of text. However, with multiline texts, return sweeps, which bring fixation from the end of one line to the beginning of the next, occur regularly and influence ~20% of all reading fixations. Our understanding of return sweeps is still limited. One common feature of return sweeps is the prevalence of oculomotor errors. Return sweeps, often initially undershoot the start of the line. Corrective saccades then bring fixation closer to the line start. The fixation occurring between the undershoot and the corrective saccade (undersweep-fixation) has important theoretical implications for the serial nature of lexical processing during reading, as they occur on words ahead of the intended attentional target. Furthermore, since the attentional target of a return sweep will lie far outside the parafovea during the prior fixation, it cannot be lexically preprocessed during this prior fixation. We explore the implications of undersweep-fixations for ongoing processing and models of eye movements during reading by analysing two existing eye-movement data sets of multiline reading.

Conversion Total Knee Arthroplasty is Associated with Increased Post-Acute Care Costs

BackgroundAlternative payment models have been viewed as successfully decreasing costs following primary total knee arthroplasty (TKA) while maintaining quality. Concerns exist regarding access to care for patients who may utilize more resources in a bundled payment arrangement. The purpose of this study is to determine if patients undergoing conversion of prior surgery to TKA have increased costs compared to primary TKA patients. MethodsClaims from Medicare and a single private insurer were queried for all primary TKA patients at our institution from 2015 to 2016. Ninety-day post-acute care costs were compared between primary and conversion TKA. Secondary endpoints included discharge disposition, complications, and readmissions. A multivariate regression analysis was performed to identify independent risk factors for increased post-acute care costs and short-term outcome metrics. ResultsOf 3999 primary TKA procedures, 948 patients (23%) underwent conversion TKA. Conversion TKA was associated with greater post-acute care costs in patients with commercial insurance ($4714 vs $3759, P = .034). Among Medicare beneficiaries, prior ligament reconstruction was associated with increased post-acute care costs ($1917 increase, P = .036), while prior fracture fixation approached statistical significance ($2402 increase, P = .055). Conversion TKA was an independent risk factor for readmissions (odds ratio 1.46, 95% confidence interval 1.00-2.17, P = .050), while patients with a prior open knee procedure had higher rates of complications (odds ratio 2.41, 95% confidence interval 1.004-5.778, P = .049). ConclusionOur data suggest that conversion from prior knee surgery to TKA is associated with increased 90-day post-acute care costs and resource utilization, particularly prior open procedures. Without appropriate risk adjustment in alternative payment models, surgeons may be financially deterred from providing quality arthroplasty care given the reduced net payment and surgical complexity of such cases.

Biceps Tenodesis versus Tenotomy at the Time of Manipulation and Lysis of Adhesions for Adhesive Capsulitis

Objectives: Although rare in the treatment of adhesive capsulitis, arthroscopic lysis of adhesions and manipulation under anesthesia (LOA/MUA) may be necessary if the patient fails conservative therapy. Patients at the time of surgery often have biceps tendon, superior labrum anterior to posterior (SLAP) pathology, or other pathology requiring concurrent treatment. Common treatments for these can include biceps tenodesis or tenotomy. Some surgeons believe that concomitant repairs at the time of LOA/MUA can cause increased stiffness post-operatively due to need for immobilization or protection, possibly leading to poorer outcomes and potentially needing further interventions such as repeat injections or repeat LOA/MUA. The goal of this study was to compare patients who underwent LOA/MUA with biceps tenodesis to those who underwent LOA/MUA with biceps tenotomy. We hypothesized that biceps tenodesis at the time of LOA/MUA did not lead to an increased risk for further intervention in the form of post-operative injections for pain or stiffness or repeat LOA/MUA compared to biceps tenotomy. Methods: A retrospective review of consecutive LOA/MUA for adhesive capsulitis performed by 5 surgeons at a single center from 2010-2016 was performed. All included patients were required to have a minimum of 1 year of follow-up, and be a minimum 2 years post-procedure. Exclusion criteria included prior biceps tenodesis, surgery within six months prior to LOA/MUA, prior infection, prior shoulder fracture or fracture fixation, and concomitant rotator cuff repair. Patients without any biceps surgery (tenotomy or tenodesis) were also excluded. The primary outcome measure was a postoperative injection in the ipsilateral shoulder for recurrent adhesive capsulitis, pain or residual stiffness. The secondary outcome measure was a repeat LOA/MUA. Statistical analysis was completed in SPSS using a chi-square analysis for categorical variables and a student’s t-test for continuous variables. Results: Fifty-five patients were included in the study. Thirty-three patients underwent biceps tenotomy, and 22 patients underwent biceps tenodesis at the time of arthroscopic LOA/MUA. The average age in the tenotomy group was 53 years and 47 years in the tenodesis group (p = 0.383). There was no significant difference in the percentage of males in the tenodesis group (59%) versus tenotomy (48%) (p = 0.440). Average body mass index (BMI) was not significantly different between the two groups (p = 0.329). No patients from either group underwent repeat LOA/MUA. Of those patients who received a biceps tenotomy, 39% had an injection for pain or stiffness post-operatively compared to 18% for biceps tenodesis, which was not significant (p=0.17). Table 1 summarizes the outcomes in both groups. Conclusion: Patients who underwent biceps tenodesis with concurrent arthroscopic LOA/MUA for adhesive capsulitis did not have a higher rate of postoperative injections or repeat LOA/MUA compared to patients who underwent biceps tenotomy at the time of LOA/MUA. [Table: see text]