Submitted abstracts for the 2009 Medical Student Research Forum are posted below. As in past years, there are two categories: Basic Research and Clinical Research projects under which abstracts may be submitted.
Basic Research Category
Monocrotaline pyrrole and NO scavenging: Golgi dispersal and inhibition of endocytic and caveolar trafficking in pulmonary arterial endothelial cells
Reuben Reich, Jason Lee, and Pravin B. Sehgal
Although the monocrotaline (MCT)/rat model is in widespread use today in studies of pulmonary arterial hypertension (PAH), the underlying mechanism(s) are poorly understood. The Sehgal lab reported previously that bovine pulmonary arterial endothelial cells (PAEC) in culture exposed to MCT-pyrrole (MCTP) for only 2 min developed megalocytosis 24-48 hr later characterized by enlarged hyperploid cells, Golgi enlargement, decreased caveolar nitric oxide (NO) and hypo-S-nitrosylation of cav-1, clathrin heavy chain (CHC), N-ethylmaleimide sensitive factor (NSF) and eNOS. We investigated whether this hypo-S-nitrosylation of trafficking mediator proteins after MCTP translated into defects in functional intracellular trafficking. We used live-cell internalization assays with different cargo ligands as tracers. For comparison we used the NO scavenger (4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (c-PTIO). Both MCTP and c-PTIO produced enlarged PAECs within 24-48 hr with markedly dispersed Golgi. Live-cell internalization assays showed that both MCTP and c-PTIO inhibited the uptake of transferrin and low-density lipoprotein (both clathrin-mediated), and of cholera toxin B (caveolin-1-mediated). Live-cell subcellular compartment labeling assays showed that Golgi-tracker (C5-ceramide) preferentially labeled a compact juxtanuclear Golgi in untreated PAECs, brightly labeled enlarged circumnuclear Golgi elements after MCTP but minimally labeled Golgi elements after c-PTIO These data provide the first direct evidence for selective functional defects in membrane internalization pathways in PAECs after exposure to MCTP and c-PTIO consistent with the hypo-S-nitrosylation of trafficking mediator proteins.
Determining Essentiality of the Macrophage Stimulating Protein Receptor in Human Cancers
Melissa A. Burns, MS IV1,2,3; Jinyan Du, Ph.D.1,2; Todd R. Golub, M.D.1,2,3
1Cancer Program, The Broad Institute of Harvard University and Massachusetts Institute of Technology, Cambridge, Massachusetts; 2Department of Pediatric Oncology, Dana-Farber Cancer Institute, Boston, Massachusetts; 3Howard Hughes Medical Institute, Chevy Chase, Maryland.
Purpose. Disruption of cell signaling pathways essential for normal metabolism by aberrant activation of tyrosine kinases has been linked with oncogenesis, yet the majority of events remain undiscovered. In a prior study, we profiled the tyrosine phosphorylation state of 63 tyrosine kinases in the human genome. This screen detected aberrant phosphorylation of the Macrophage Stimulating Protein Receptor, a receptor tyrosine kinase commonly called Ron, in a subset of human cancer cell lines. In this study, we aim to determine whether Ron is activated and essential in oncogenesis, and, therefore, a potential therapeutic target.
Methods. Cancer cell lines with aberrant Ron phosphorylation were treated with SU11274, PHA665752, or PF2341066, small molecule inhibitors determined to target Ron and/or the related tyrosine kinase, Met, through phosphorylation profiling of kinase-specific overexpression plasmids. Viability of treated cell lines was measured at 48, 72, and 96 hours. Because the inhibitors are nonspecific, we undertook a genetic strategy to determine the biologically relevant target, whereby drug-resistant alleles were constructed and tested for their ability to rescue the inhibitor’s effects. To do this, we utilized a conserved leucine residue, known as the “gatekeeper,” which is essential for drug sensitivity and for which a known mutation, L1213V, confers drug resistance. We engineered this mutation into Ron and Met plasmids using Gateway cloning technology, introduced the wild type or mutant kinase by lentiviral transduction into sensitive cell lines, and subjected them to a cell viability assay and phosphorylation profiling.
Results. Prior studies identified aberrant phosphorylation of Ron in human breast, lung, colon, and pancreatic cancer cell lines. Phosphorylation profiling of Ron and Met overexpression plasmids identified PF2341066, but not SU11274 or PHA665752, as an inhibitor of Ron. Of the cell lines with aberrantly activated Ron, we identified six with decreased cell viability after treatment with PF2341066. Of these, cell viability of the pancreatic cancer cell line, AsPC-1, is rescued by the introduction of the L1213V Ron mutant. Furthermore, phosphorylation profiling identified that Ron is in fact the biologically relevant target of PF2341066 in the AsPC-1 cell line.
Conclusions. Through a combination of proteomic and genetic techniques, we identified Ron as a potential therapeutic target in human pancreatic cancers. Importantly, this discovery would not have been uncovered by the cancer genome resequencing efforts, as the Ron coding sequence remains intact. Future studies should be aimed at elucidating the role of Ron in human pancreatic cancer and determining whether the results presented here can be translated into in vivo studies.
Hepatic Progenitor Cells: Their Possible Role in Recurrent HCV and Allograft Loss
Seth Sclair MS IV, M. Isabel Fiel MD, Hai-Shan Wu PhD, John Doucette PhD,
Costica Aloman MD , Thomas Schiano MD
Departments of Medicine/Liver Diseases, Pathology, & Community and Preventive Medicine
Mount Sinai School of Medicine, New York, NY
Background: HCV is the most common indication for liver transplantation (LT). The cholestatic variant of HCV (cvHCV) is characterized by rapid HCV progression leading to graft loss. Older donor age is associated with aggressive disease and rapid fibrosis progression. Ductular reaction (DR), believed to arise from hepatic progenitor cells (HPC) is associated with hepatic fibrosis.
Objective: The aims of this study are to demonstrate the HPC count and DR in the following three clinical outcomes of recurrent HCV: stable histology (no >stage 2 of 4 fibrosis), cirrhosis, and cvHCV and to demonstrate the association between HPC, DR, and donor age.
Methods: Using the LT database, a search for HCV cases from 1992-2007 yielded 903 cases, in which 203 had donor age >60 yrs and 195 donor age <30 yrs. Cases of re-LT, living donor LT, HIV, CMV, HBV co-infection, concurrent bile duct problem, and rejection were excluded. Liver biopsies (bx) from time of LT (pre- and post-perfusion) and serially thereafter were reviewed by a liver pathologist (MIF). Sections from paraffin blocks were immunostained with CK7 delineating HPC and bile ductules. Five portal/periportal areas were inspected for HPC (via manual cell count) and photographed at 200X magnification and were analyzed by a novel image analysis technique that calculated DR as % area with (+) CK7 stain.
Results: 20 cases of stable histology (9 with donor age >60 yrs, 11 with donor age <30), 23 cases of cirrhosis (13 with donor age >60 yrs, 10 with donor age <30), and 9 cases of cvHCV (7 with donor age> 60 yrs, 2 with donor age <30) were identified. There was no significant relationship for HPC count or DR at baseline bx between all outcome groups and donor age. At bx showing initial recurrent HCV, mean HPC count for the cirrhosis group (4.3) was greater than the stable (1.9, p <0.05) and cvHCV (2.0) groups; DR for the cvHCV group (3.7%) was greater than the stable (1.3%, p < 0.05) and the cirrhosis group (2.8%, p=NS). At endpoint bx, HPC count was higher in the cvHCV (6.1) vs. stable (0.92, p <0.05) and cirrhosis (4.1) vs. stable (p <0.05) groups. Mean DR for the cvHCV, cirrhosis, and stable groups were 6.0%, 3.4%, 1.3%, respectively (p <0.05). At endpoint bx, DR was significantly higher in all bx for donor age >60 yrs when compared to endpoint bx with donor age <30 yrs (p=0.019).
Discussion: There are no differences in HPC count and DR in pre- and post-perfusion bx at time of LT. At initial bx showing recurrent HCV, the cirrhosis group showed increased HPC counts and the cvHCV showed increased DR. At endpoint bx the HPC response is greatest in the cvHCV > cirrhosis > stable cases. DR may play a role in aggressive HCV recurrence post-LT. The cvHCV rarely occurs in donors <30 yrs.
INFRARED THERMOMETRY AND OCT OF BOVINE FASCIAL TISSUE FOLLOWING Ho:YAG LASER IRRADIATION
Michael H. Li MSII; Brian J. Wong, M.D, Ph.D. Department of Otolaryngology, Beckman Laser
Institute and Medical Clinic, University of California, Irvine.
Purpose. Several studies have identified a temperature regime of 60°C to 80°C during laser heating facilitates the contraction or tightening of collagen rich tissues with minimal acute thermal injury, and direct laser irradiation (DLI) is able to accomplish this. Developing this minimally-invasive tissue tightening method requires a more thorough understanding between tissue structural properties and temperature. The purpose of this study was to: (1) determine the relationship between laser dosimetry and peak tissue temperature in fascial tissues during DLI and (2) monitor structural changes in the tissue following DLI via optical coherence tomography (OCT). This pilot work is aimed at identifying dosimetry parameters that might be useful in the development of tissue tightening procedures for use in facial aesthetic surgery.
Methods. Fascia from bovine diaphragm specimens was used as a model for human fascial tissues potentially encountered in facial aesthetic surgical procedures. Specimens 1.0mm thick were placed 10.0mm from a multimode fiber delivering light from a Ho:YAG laser ( =2100nm). The water content of the fascia was controlled by coupling the non-irradiated surface of the tissue to the outflow tract of an ultrasonic humidifier. DLI of samples were tested at wattages (1.5W-3.0W), spot diameters (1.0mm-3.50mm), pulse repetition rates (PRR) of 5Hz-8Hz-12Hz, and pulses (1-10) resulting in peak temperatures ranging 35°C through 100°C. Surface temperature profiles were recorded using an IR camera. Select samples were imaged using OCT to determine tissue thickness pre and post DLI, a measure of collagen contraction.
Results. PRR had little impact (=4 °C) when normalized by total pulse delivery. As expected, increasing pulse number with constant power and PRR, produced peak temperatures of 35°C through 100°C. In general, three to six pulses were needed to heat tissue to 60°C to 80°C, and OCT images confirmed a two-fold increase in specimen thickness.
Conclusions. This study provides baseline dosimetry needed to shrink fascial tissue using light from a Ho:YAG laser. Potential applications include developing percutaneous and other minimally invasive techniques for facial rejuvenation.
This work was supported by the U.S. Air Force Office of Scientific Research, Medical Free-Electron Laser Program (FA9550-04-1-0101). The U.S. Government is authorized to reproduce and distribute reprints for Governmental purposes notwithstanding any copyright notation. The views and conclusions contained herein are those of the authors and should not be interpreted as necessarily representing the official policies or endorsements, either expressed or implied, of the Air Force Research Laboratory or the U.S. Government.
Clinical Research Category
The Effect of Stimulants on Pediatric Aggression
Alanna Chait, MSI; Julie A. Sarsfield, B.A.; Sophie Woolston, B.A.; Matthew Perkins, M.D.; Elizabeth Pappadopulos, Ph.D., Peter S. Jensen, M.D.
Department of Child Psychiatry, Columbia University/NYSPI; New York, New York.
Purpose. Maladaptive aggression is a critical target for psychiatric research because of its association with longer, more intensive treatments and poorer outcomes. Research on stimulants is particularly important, as these agents are often prescribed for conditions that co-occur with impulsive aggression, most notably Attention Deficit Hyperactivity Disorder (ADHD) and the disruptive behavior disorders (DBDs) (conduct disorder (CD) and oppositional defiant disorder (ODD)). While more than 160 controlled trials have demonstrated the efficacy of stimulants in managing ADHD symptoms for up to 24 months1, few studies have directly examined their impact on aggressive behaviors in real-world settings. Therefore, this study sought to investigate the degree of clinical change associated with stimulants for treating aggression related to DBDs. We reviewed randomized, controlled trials (RCTs) of stimulants in aggressive youth and reported the efficacy and effect sizes (ES) of these agents in managing persistent behavioral problems. Our results identified which stimulants are associated with the most powerful effects on aggression in real-world settings.
Methods. Studies were identified in Medline, PsychInFO, and EMBASE searches of the literature from 1980 to November 2005. Studies in this review (1) were RCTs with or without a drug-free washout period, (2) addressed overt aggression, (3) reported the end point mean and standard deviation (SD) on a rating scale of overt aggression, CD, or ODD, (4) were published in a peer-reviewed journal, (5) studied subjects < 19 years, and (6) were published in English. ES values were computed using Cohen’s d2, which holds that an ES < 0.2 is a small effect; 0.21 to 0.5 is a medium effect; and > 0.8 is a large effect2. For studies with multiple raters, ES values were averaged to determine the overall ES.
Results. 19 RCTs of stimulants measured aggressive behavior. These studies examined a total of 1057 subjects (average n = 55.6; 84.2% male; average age = 9.1 years). Primary diagnoses included ADHD, autism, mental retardation, and DBD, and 12 allowed for co-morbid diagnoses of CD, ODD, or ADHD. Average study length was 27.2 days. Overall, stimulants exerted a medium to large effect (mean ES = 0.78) on pediatric aggression. Methylphenidate (MPH) was notably effective with an ES of 0.9
Conclusions. Stimulants exerted a medium to large ES for aggression associated with ADHD, CD, and ODD, and therefore have the potential to improve persistent behavioral problems in real-world settings. The greatest effects will most likely be seen with methylphenidate (MPH) for ADHD and co-morbid disruptive behavior problems (mean ES = 0.90). The large ESs associated with MPH for aggression are equivalent to those seen in stimulants for ADHD alone, which are perhaps the strongest treatment improvements observed in child psychiatry. These results are also noteworthy in light of the severity of adverse events associated with the antipsychotics, which are often used adjunctively to treat aggression. Our findings indicate that it may be beneficial to conduct a full therapeutic trial of stimulants before using antipsychotics
Quantitative Anatomic Measurements of the Anteromedial and Posterolateral Bundles of the Anterior Cruciate Ligament
Timothy P. Capecchi, MSII; Nicholas F. Anderson, MSII; Benjamin D. Westerhaus, BS; Michael P. Walsh, MSIII; Coen A. Wijdicks, MS; Robert F. LaPrade, M.D. Ph.D.
Department of Orthopaedic Surgery, University of Minnesota, Minneapolis, MN
Purpose: The anterior cruciate ligament (ACL) consists of two distinct bundles, named the anteromedial (AM) and posterolateral (PL) bundles relative to their tibial attachments and distinguished by their reported functional roles. The purpose of the present study was to examine bony and soft tissue landmarks and to provide a quantitative assessment of the anatomy of the femoral and tibial attachments of the anteromedial and posterolateral ACL bundles.
Methods: Ten femur and 10 tibia bone specimens were examined to evaluate common osseous landmarks on the tibial plateau and femoral condyle. A six-degree-of-freedom electromagnetic tracking device (Polhemus Liberty FASTRAK) was used to record the three-dimensional coordinates of landmarks of interest. Ten non-paired fresh-frozen cadaveric knees were dissected and examined to determine the location of the AM and PL bundles relative to osseous and soft tissue landmarks. Areas and straight-line distances to significant anatomic landmarks were recorded using the Polhemus system.
Results: Qualitative analysis of the tibia bone specimens revealed the attachment of the anterior horn of the lateral meniscus was localized in an oval depression on the tibia 2.45 ± 1.26 mm medially from the lateral cartilage border. Medially, this fossa sloped upwards and formed a plateau. This plateau was bordered by an anterior ridge, which we will call the anteromedial (AM) ridge. The most lateral prominence of the AM ridge, which we will call the AM tubercle, was located 6.19 ± 2.21 mm laterally from the closest medial cartilage border. Qualitative analysis of fresh-frozen specimens showed the AM bundle center was 8.58 ± 1.73 mm posterior to the AM tubercle. The PL bundle center was 5.08 ± 1.28 mm from the posterior aspect of the anterior horn of the lateral meniscus.
Qualitative analysis of the bone box femurs demonstrated that two ridges were present in the area of the ACL insertion. The lateral intercondylar ridge (“Resident’s Ridge”), which was observed in all ten bone specimens, was easily identified upon visual and tactile examination. The bifurcate ridge was found in 6 out of 10 specimens and was often difficult to visualize. Quantitative analysis of the cadaveric specimens showed the average distance from the midpoint of the lateral intercondylar ridge to the AM insertion center was 8.34 ± 2.23 mm, and 8.49 ± 2.69 mm to the PL insertion center. The lateral intercondylar ridge was 11.06 ± 2.55 mm in length, spanning from the deep superior intercondylar notch to a variable position on the shallow inferior lateral condyle, just deep to the ACL insertion.
Conclusions: Our study described a novel AM ridge which was found on all fresh-frozen specimens at the anterior border of the AM bundle. This ridge may be a useful guide in the placement of the AM bundle. The anterior horn of the lateral meniscus was the closest soft tissue landmark for placement of the tibial AM and PL bundles. We found that the lateral intercondylar ridge was consistent and easily identifiable, coursing along the superior aspect of the femoral ACL footprint at 90º flexion. In conclusion, improved knowledge of relevant bony and soft tissue attachment sites may improve anatomic ACL bundle placement and lead to more consistent techniques and improve surgical outcomes.
Assessment of GABA using the J-edited Spin Echo Difference Method at 3 Tesla in Patients with Treatment Resistant Major Depressive Disorder
Paul S. Nestadt, MS II; Sanjay J. Mathew, M.D.; Xiangling Mao, Ph.D.; Dennis S. Charney, M.D.; Dikoma C. Shungu, Ph.D.
Department of Psychiatry, Mount Sinai School of Medicine, New York, New York; Department of Radiology, Weill Medical College of Cornell University, New York, New York.
Purpose. Previous proton magnetic resonance spectroscopy studies in major depressive disorder (MDD) have shown reductions in occipital lobe GABA concentrations of approximately 30-50% and glutamate elevations of approximately 10%. To our knowledge, no studies in MDD have examined GABA and glutamate+glutamine (Glx) in relation to antidepressant medication-resistance, which may help identify more homogeneous MDD subgroups. This study compared occipital cortex GABA and Glx in healthy controls and unmedicated, symptomatic MDD patients with and without treatment-resistance.
Methods. We studied 22 adult patients with MDD (12 M, 10 F) and 19 healthy volunteers (9M, 10F). Criterion for treatment-resistant depression (TRD) was failure to respond to at least 2 trials of standard antidepressants in the current episode (SSRIs, SNRIs or bupropion. All subjects were medication-free for at least 1 week prior to scan and had negative urine toxicologies on scan day. The MDD sample was moderately depressed, with day-of-scan Hamilton Depression Rating Scale scores of 20.3 (SD = 5.6) with significant comorbid anxiety (Hamilton Anxiety Rating Scale = 22.8 (SD = 8.7). 7 of 22 met criteria for TRD, and 13 patients had “anxious depression.” Occipital lobe GABA and Glx were recorded in 13 min from 3x3x2 cm3 voxels with an 8-channel phased-array coil using the J-editing technique (TE/TR 68/1500ms) on a 3 T MR system. Mean peak areas for metabolites of interest were obtained by frequency-domain nonlinear least-squares procedures, and then expressed as ratios relative to the unsuppressed voxel tissue water signal (W).
Results. MDD (n = 15) and TRD subgroups (n = 7) did not differ in demographic or clinical measures. In occipital cortex, GABA/W was significantly lower in TRD patients than in non-TRD MDD patients (p ≤ .005) and to healthy controls (p ≤ .001). Occipital Glx/W did not differ between groups. In the TRD subgroup, GABA/W and day-of-scan depressive symptoms were negatively correlated (r = -.68, p = .09), while a positive correlation between GABA/W and depression severity was found in the non-treatment-resistant MDD group (r = .48, p = .069), both at trend level.
Conclusions. Occipital GABA was lower in TRD patients than in non-resistant MDD patients or healthy controls. TRD and MDD groups differed significantly in the relationship of GABA to depressive severity. Poor response to standard antidepressants may be associated with impaired GABA synthesis, suggesting alternative treatment approaches targeting amino acid neurotransmitter regulation.
Safety and Efficacy of Repeat Drug-Eluting Stent Implantation in Patients with Drug-Eluting Stent Failures
Donna LaMonica, MS II; Jenny Z. Qin, R.N., Roxanna Mehran, M.D.; Jeffrey Moses, M.D.; Martin Leon, M.D.
Cardiovascular Research Foundation, Division of Interventional Cardiology, New York Presbyterian Hospital, Columbia University Medical Center
Purpose: Drug-eluting stents (DES) have reduced, but not completely eliminated in-stent restenosis (ISR). While the treatment of bare metal in-stent restenosis has always been challenging and has involved various approaches (intracoronary brachytherapy, cutting balloon angioplasty, directional coronary atherectomy, rotational coronary atherectomy, and DES implantation), the optimum strategy for treating this new entity, DES failures, is completely unknown.
Methods: From August 2004 to May 2005, 52 pts presented to Columbia University Medical Center with 65 DES failure lesions: 58 Cypher failures, 6 Taxus failures, and 1 patient with an unknown type of DES. Mean patientt age was 62±11 yrs, 76% were male, 33% presented with unstable angina, and 42% had diabetes. Lesion location was left main (n=1), LAD (n=24), LCX (n=10), RCA (n=19), and SVG (n=11). Thirteen Cypher failures were treated with repeat Cypher implantation, 39 Cypher failures were treated with a Taxus stent, 5 Cypher failures were treated with balloon angioplasty, and 1 percutaneous treatment of a Cypher stent failure was unsuccessful. Five Taxus failures were treated with a Cypher stent, and 1 Taxus failure was treated with repeat Taxus stent implantation. The one patient with failure of an unknown type of DES was treated with balloon angioplasty.
Results: There were no in-hospital major adverse cardiac events or troponin-I elevations; n=0 for cardiac death, myocardial infarction, CPK, target vessel or lesion revascularization. In the six months following repeat stenting, zero cardiac deaths, 1 myocardial infarction (1/51, 2%), 2 target lesion revascularization (2/51, 4%), 1 target vessel revascularization (1/51, 2%), and zero non-target vessel-revascularization. This totals to 4 major adverse cardiac events post re-implantation, or 8%.
Conclusions: In this non-selected cohort of patients, the use of repeat drug-eluting stent implantation is a safe and effective strategy for first time drug eluting stent lesions.
Kidney Transplantation in Recipients with a Prior Heart Transplant
James Cassuto 1, MS I; Roy Bloom 2, MD; Alden Doyle 2, MD, MS, MPH; Peter Reese 2, MD;
Ali Naji 3, MD, PhD; Peter Abt 3, MD
1 New York Medical College, Valhalla, NY
2 Department of Nephrology, Hospital of the University of Pennsylvania, Philadelphia, PA
3 Department of Surgery, Hospital of the University of Pennsylvania, Philadelphia, PA
Purpose. Chronic renal disease among prior heart transplant recipients is a growing problem that is likely to place an increased demand on a limited supply of renal grafts. Allocation of these limited resources requires consideration of the competing demands between optimal organ utility and fair distribution. This study sought to compare kidney transplant outcomes in recipients of kidney after prior heart transplantation (KAH) with kidney transplantation in other clinical settings.
Methods. A retrospective cohort study using registry data from the UNOS database (1995-2007) was performed comparing renal graft survival among KAH (N=449) recipients to patients who underwent simultaneous kidney heart transplant (SKH), isolated primary kidney transplant (KA1) or repeat isolated kidney transplant (KA2). Factors associated with KAH graft failure were identified with multivariable regression analysis.
Results. The annual number of KAH recipients tripled over the study period. In an adjusted analysis of overall graft survival KAH was similar to KA2 (HR= 0.92, CI=0.71-1.19), but was inferior to KA1 (HR=0.73, CI=0.57-0.94) or SKH (HR=0.68, CI=0.46-1.00). Adjusted death censored graft survival provided evidence that KAH was similar to KA2 (HR=0.91, CI=0.63-1.33), KA1(HR=0.73, CI=0.5-1.06) , but inferior to SKH (HR= 0.34, CI=0.17-0.68). Among KAH recipients, death censored graft failure was associated with delayed graft function (HR=3.39, CI=1.55-7.39) and increased cold ischemic time (HR=1.04, CI=1.01-1.06). A longer time interval between heart and kidney transplant was associated with improved graft survival (HR=0.85, CI=0.76-0.95), as was a greater time interval between heart transplant and the development of renal failure (HR=0.88, CI=0.81-0.96).
Conclusion. Kidney graft survival among prior heart transplant recipients is inferior to isolated primary kidney transplant recipients. The increased graft loss is primarily due to patient death. Transplant professionals may wish to consider whether KAH is a judicious use of allografts.
Plate Fixation using Contoured LC-DCP for well implanted proximal femoral periprosthetic fractures.
Richard Anderson, MS II; Sreevathsa Boraiah, MD; Scott Rusinoff, MD; David E. Asprinio, MD
Department of Orthopedic Surgery, The Westchester Medical Center; New York Medical College, Valhalla, NY
Introduction: Obtaining rigid proximal fixation around well implanted femoral stems in periprosthetic fractures can be challenging. Of the variety of implants used, plate fixation with cables remains popular, however firm purchase may not be obtained around the proximal fragment. We assessed the outcomes of periprosthetic fractures managed with contoured LC-DCP which allowed for more rigid proximal fixation.
Materials and Methods: Eighteen patients underwent plate osteosynthesis for proximal femoral periprosthetic fractures. Sixteen were managed with contoured LC-DCP and formed the study cohort. The plate was anatomically contoured in the coronal plane to fit until the tip of the greater trochanter. In addition to the cables below the lesser trochanter, unicortical trochanteric screws or cables above the lesser trochanter were used to achieve a rigid proximal fix. The average follow up duration was 60 months. Clinical and radiographic information was assessed. Harris Hip Score (HHS) was used as a functional outcome tool.
Results: The average patient age was 80 years. According to Vancouver classification there were 12 B1 and 4 C fracture patterns. In 15 patients unicortical locking trochanteric screws were used, while cable fixation above the lesser trochanter was performed in 1 patient. Fourteen (87.5%) of the sixteen patients healed successfully. Two patients (12.5%) needed revision of the femoral stem due to failure of surgical fixation. The average HHS was 78.
Conclusion: Contouring the plate to fit the greater trochanter helps in achieving anatomic reduction and a more rigid proximal fix. This may help in decreasing the failure rates and improved functional outcome.