Clinical Focus

  • Orthopaedic Surgery
  • Pediatric Spinal Deformity
  • Pediatric Hip Disorders
  • Neuromuscular Disorders
  • Pediatric Orthopaedic Trauma
  • General Pediatric Orthopaedics
  • Foot and Ankle

Academic Appointments

Professional Education

  • Board Certification: Orthopaedic Surgery, American Board of Orthopaedic Surgery (2019)
  • Board Certification,, American Board of Orthopaedic Surgery,, Orthopaedic Surgery (2019)
  • Fellowship:University of Texas Southwestern Pediatric Orthopaedic Surgery Fellowship (2017) TX
  • Residency:Stanford University Orthopaedic Surgery Residency (2016) CA
  • Medical Education:Stanford University School of Medicine Registrar (2011) CA


All Publications

  • Severity Adjusted Risk of Long-Term Adverse Sequelae Among Children with Osteomyelitis. The Pediatric infectious disease journal Vorhies, J. S., Lindsay, E. A., Tareen, N. G., Kellum, R. J., Jo, C. H., Copley, L. A. 2018


    BACKGROUND: The purpose of this investigation is to evaluate the risk for long-term, adverse outcomes among children with osteomyelitis.METHODS: Children with osteomyelitis were prospectively enrolled from 2012-2014. Care was accomplished by a multidisciplinary team according to an institutional algorithm. Data was collected to define the severity of illness during the initial hospitalization and assess short, intermediate and long-term outcomes. Clinical examination, radiographic assessment, and functional outcome survey administration were performed at a minimum of 2 year follow-up. A comparison cohort analysis was performed according to initial severity of illness score (SIS) of mild (0-2), moderate (3-6), and severe (7-10).RESULTS: Of 195 children enrolled, 139 (71.3%) returned for follow-up at an average of 2.4 years (range 2.0 to 5.0 years). Children with severe illness were less likely to have normal radiographs (Severe - 4.0%; Moderate - 38.2%; Mild - 53.2%, p<0.0001), and more likely to have osteonecrosis, chondrolysis, or deformity (Severe - 32.0%; Moderate - 5.9%; Mild - 1.3%, p<0.0001). Functional outcome measures did not significantly differ between severity categories.By regression analysis SIS, plus age less than 3 years and MRSA predicted severe sequelae with an area under the curve of 0.8617 and an increasing odds ratio of 1.34 per point of increase in severity score.CONCLUSION: Long term severe adverse outcomes among children with osteomyelitis occurred in 11 of 139 (7.9%) children and were predicted by initial severity of illness. Other risks that diminished the likelihood of complete resolution or increased the risk of severe sequelae included MRSA etiology and young age. The majority of children with osteomyelitis do not require long term follow-up beyond the initial treatment period.LEVEL OF EVIDENCE: Level II, Prognostic, Prospective Cohort Comparison.

    View details for PubMedID 29742649

  • Treatment of Degenerative Lumbar Spondylolisthesis With Fusion or Decompression Alone Results in Similar Rates of Reoperation at 5 Years. Clinical spine surgery Vorhies, J. S., Hernandez-Boussard, T., Alamin, T. 2018; 31 (1): E74–E79


    Population-based analysis of administrative discharge records from California, Florida, and New York inpatient, ambulatory, and emergency department settings between 2005 and 2011, utilizing Healthcare Cost and Utilization Project data.We aimed to compare, and characterize rates of reoperation and readmission among patients with degenerative spondylolisthesis treated with surgical decompression alone versus fusion.Degenerative lumbar spondylolisthesis with stenosis can be treated by decompression with or without fusion. Fusion has traditionally been preferred. We hypothesized that rates of reoperation after decompression alone would be higher than after fusion.We undertook a population-based analysis of administrative discharge records from California, Florida, and New York inpatient, ambulatory, and emergency department settings between 2005 and 2011, with Healthcare Cost and Utilization Project data. We identified all patients who had degenerative spondylolisthesis who were treated with decompression alone or with fusion and compared their rates of reoperation at 1, 3, and 5 years from the index operation. We used descriptive statistics and a hierarchical logistic regression model to generate risk-adjusted odds of all-cause readmissions.Our study consisted of 75,024 patients with spondylolisthesis; 6712 (8.95%) of them underwent decompression alone and 68,312 (91.05%) of them underwent fusion. Rates of reoperation were higher for decompression versus fusion at 1 year; 6.87% versus 5.53% (P≤0.001), but at 3 years; 13.86% versus 12.91% (P=0.18) and 5 years; 16.9% versus 17.7% (P=0.398) years rates of reoperation were not statistically different. Patients treated with decompression alone that had a second operation tended to have the operation sooner 512.6 versus 567.4 days (P=0.008).Our study suggests that treatment of degenerative spondylolisthesis with fusion or decompression alone results in similar rates of reoperation at 5 years. This medium term data indicate that decompression alone may be a viable treatment for some patients with degenerative spondylolisthesis.

    View details for PubMedID 28671881

  • Pediatric Supracondylar Humerus Fractures: Does After-Hours Treatment Influence Outcomes? Journal of orthopaedic trauma Paci, G. M., Tileston, K. R., Vorhies, J. S., Bishop, J. A. 2018; 32 (6): e215–e220


    To compare the outcomes of pediatric supracondylar humerus fractures treated during daytime hours to those treated after-hours.Retrospective.Academic Level I trauma center.Two hundred ninety-eight pediatric patients treated with surgical reduction and fixation of closed supracondylar fractures were included.Seventy-seven patients underwent surgery during daytime hours (06:00-15:59 on weekdays). One hundred eighty-six patients underwent surgery after-hours (16:00-05:59 on weekdays and any surgery on weekends or holidays).Surgeon subspecialty, operative duration, and radiographic and clinical outcomes, including range of motion and carrying angle, were extracted from the patient medical records.There were no patient-related demographic differences between the daytime hours and after-hours groups. Daytime surgery was more likely to be performed by a pediatric orthopaedic surgeon than after-hours surgery. Fractures treated after-hours had more severe injury patterns. After-hours surgery was not independently associated with rate of open reduction, operative times, complications, achievement of functional range of motion, or radiographic alignment. A late-night surgery subgroup analysis demonstrated an increased rate of malunion in patients undergoing surgery between the hours of 23:00 and 05:59.There is no difference in the operative duration or outcomes after surgical treatment of pediatric supracondylar humerus fractures performed after-hours when compared with daytime surgery. However, late-night surgery performed between 23:00 and 05:59 may be associated with a higher rate of malunion. Surgeons can use these data to make better-informed decisions about the timing of surgery in this patient population.Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

    View details for PubMedID 29432316

  • Does the Watson-Jones or Modified Smith-Petersen Approach Provide Superior Exposure for Femoral Neck Fracture Fixation? Clinical orthopaedics and related research Lichstein, P. M., Kleimeyer, J. P., Githens, M., Vorhies, J. S., Gardner, M. J., Bellino, M., Bishop, J. 2018


    A well-reduced femoral neck fracture is more likely to heal than a poorly reduced one, and increasing the quality of the surgical exposure makes it easier to achieve anatomic fracture reduction. Two open approaches are in common use for femoral neck fractures, the modified Smith-Petersen and Watson-Jones; however, to our knowledge, the quality of exposure of the femoral neck exposure provided by each approach has not been investigated.(1) What is the respective area of exposed femoral neck afforded by the Watson-Jones and modified Smith-Petersen approaches? (2) Is there a difference in the ability to visualize and/or palpate important anatomic landmarks provided by the Watson-Jones and modified Smith-Petersen approaches?Ten fresh-frozen human pelvi underwent both modified Smith-Petersen (utilizing the caudal extent of the standard Smith-Petersen interval distal to the anterosuperior iliac spine and parallel to the palpable interval between the tensor fascia lata and the sartorius) and Watson-Jones approaches. Dissections were performed by three fellowship-trained orthopaedic traumatologists with extensive experience in both approaches. Exposure (in cm) was quantified with calibrated digital photographs and specialized software. Modified Smith-Petersen approaches were analyzed before and after rectus femoris tenotomy. The ability to visualize and palpate seven clinically relevant anatomic structures (the labrum, femoral head, subcapital femoral neck, basicervical femoral neck, greater trochanter, lesser trochanter, and medial femoral neck) was also recorded. The quantified area of the exposed proximal femur was utilized to compare which approach afforded the largest field of view of the femoral neck and articular surface for assessment of femoral neck fracture and associated femoral head injury. The ability to visualize and palpate surrounding structures was assessed so that we could better understand which approach afforded the ability to assess structures that are relevant to femoral neck fracture reduction and fixation.After controlling for age, body mass index, height, and sex, we found the modified Smith-Petersen approach provided a mean of 2.36 cm (95% confidence interval [CI], 0.45-4.28 cm; p = 0.015) additional exposure without rectus femoris tenotomy (p = 0.015) and 3.33 cm (95% CI, 1.42-5.24 cm; p = 0.001) additional exposure with a tenotomy compared with the Watson-Jones approach. The labrum, femoral head, subcapital femoral neck, basicervical femoral neck, and greater trochanter were reliably visible and palpable in both approaches. The lesser trochanter was palpable in all of the modified Smith-Petersen and none of the Watson-Jones approaches (p < 0.001). All modified Smith-Petersen approaches (10 of 10) provided visualization and palpation of the medial femoral neck, whereas visualization of the medial femoral neck was only possible in one of 10 Watson-Jones approaches (p < 0.001) and palpation was possible in eight of 10 Watson-Jones versus all 10 modified Smith-Petersen approaches (p = 0.470).In the hands of surgeons experienced with both surgical approaches to the femoral neck, the modified Smith-Petersen approach, with or without rectus femoris tenotomy, provides superior exposure of the femoral neck and articular surface as well as visualization and palpation of clinically relevant proximal femoral anatomic landmarks compared with the Watson-Jones approach.Open reduction and internal fixation of a femoral neck fracture is typically performed in a young patient (< 60 years old) with the objective of obtaining anatomic reduction that would not be possible by closed manipulation, thus enhancing healing potential. In the hands of surgeons experienced in both approaches, the modified Smith-Petersen approach offers improved direct access for reduction and fixation. Higher quality reductions and fixation are expected to translate to improved healing potential and outcomes. Although our experimental results are promising, further clinical studies are needed to verify if this larger exposure area imparts increased quality of reduction, healing, and improved outcomes compared with other approaches. The learning curve for the exposure is unclear, but the approach has broad applications and is frequently used in other subspecialties such as for direct anterior THA and pediatric septic hip drainage. Surgeons treating femoral neck fractures with open reduction and fixation should familiarize themselves with the modified Smith-Petersen approach.

    View details for PubMedID 29698292

  • Admission Through the Emergency Department Is an Independent Risk Factor for Lower Satisfaction With Physician Performance Among Orthopaedic Surgery Patients: A Multicenter Study JOURNAL OF THE AMERICAN ACADEMY OF ORTHOPAEDIC SURGEONS Vorhies, J. S., Weaver, M. J., Bishop, J. A. 2016; 24 (10): 735-742


    Patient experience data are increasingly used to guide performance improvement and to determine physician and hospital reimbursement. We studied the relationship between emergency department (ED) admission and patient satisfaction with physicians' performance, and identified other associated predictors.We evaluated 6,524 inpatient Press Ganey patient experience surveys from two academic level I trauma centers over 5 years. We stratified patients by ED admission or other admission and compared the proportions of patients in each group who were satisfied with physician performance. We used logistic regression to control for demographic differences and characteristics of hospitalizations.Among patients admitted through the ED, 85.18% were satisfied, compared with 89.44% of patients admitted through other pathways (P < 0.001). Admission through the ED predicted decreased satisfaction, with an odds ratio of 0.67 (P = 0.032) after controls were applied through logistic regression.Admission through the ED is an independent risk factor for lower satisfaction with physician performance. Understanding the determinants of patient satisfaction will help improve physician-patient interactions and guide quality improvement and value-based reimbursement initiatives.This retrospective survey-based analysis of satisfaction does not fall clearly under any of the Journal's established categories of level of evidence. The most closely aligned choice would be Level III Prognostic.

    View details for DOI 10.5435/JAAOS-D-16-00084

    View details for Web of Science ID 000385408400010

    View details for PubMedID 27579815

  • Growth mechanisms and geochemistry of carbonate concretions from the Cambrian Wheeler Formation (Utah, USA) SEDIMENTOLOGY Gaines, R. R., Vorhies, J. S. 2016; 63 (3): 662-698

    View details for DOI 10.1111/sed.12234

    View details for Web of Science ID 000372342200007

  • Legal restrictions and complications of abortion: Insights from data on complication rates in the United States JOURNAL OF PUBLIC HEALTH POLICY Rolnick, J. A., Vorhies, J. S. 2012; 33 (3): 348-362


    Although US federal law requires all American states to permit abortion within their borders, states retain authority to impose restrictions.We used hospital discharge data to study the rates of major abortion complications in 23 states from 2001 to 2008 and their relationship to two laws: (i) restrictions on Medicaid – the state insurance programs for the poor – funding, and (ii) mandatory delays before abortion. Of 131 000 000 discharges in the data set, 10 980 involved an abortion complication. The national rate for complications was 1.90 per 1000 abortions (95 per cent CI: 1.57–2.23). Eleven states required mandatory delays and 12 restricted funding for Medicaid participants. After controlling for socioeconomic characteristics and the pregnancy complication rate, legal restrictions were associated with lower complication rates: mandatory delays (OR 0.79(0.65–0.95)) and restricted Medicaid funding (OR 0.74 (0.61–0.90)). This result may reflect the fact that states without restrictions perform a higher percentage of second-trimester abortions. This study is the first to assess the association between legal restrictions on abortion and complication rates.

    View details for DOI 10.1057/jphp.2012.12

    View details for Web of Science ID 000307793800010

    View details for PubMedID 22622483

  • Decreased Length of Stay After TKA Is Not Associated With Increased Readmission Rates in a National Medicare Sample CLINICAL ORTHOPAEDICS AND RELATED RESEARCH Vorhies, J. S., Wang, Y., Herndon, J. H., Maloney, W. J., Huddleston, J. I. 2012; 470 (1): 166-171


    There is a trend toward decreasing length of hospital stay (LOS) after TKA although it is unclear whether this trend is detrimental to the overall postoperative course. Such information is important for future decisions related to cost containment.We determined whether decreases in LOS after TKA are associated with increases in readmission rates.We retrospectively reviewed the rates and reasons for readmission and LOS for 4057 Medicare TKA patients from 2002 to 2007. We abstracted data from the Medicare Patient Safety Monitoring System. Hierarchical generalized linear modeling was used to assess the odds of changing readmission rates and LOS over time, controlling for changes in patient demographic and clinical variables.The overall readmission rate in the 30 days after discharge was 228/4057 (5.6%). The 10 most common reasons for readmission were congestive heart failure (20.4%), chronic ischemic heart disease (13.9%), cardiac dysrhythmias (12.5%), pneumonia (10.8%), osteoarthrosis (9.4%), general symptoms (7.4%), acute myocardial infarction (7.0%), care involving other specified rehabilitation procedure (6.3%), diabetes mellitus (6.3%), and disorders of fluid, electrolyte, and acid-base balance (5.9%); the top 10 causes did not include venous thromboembolism syndromes. We found no difference in the readmission rate between the periods 2002-2004 (5.5%) and 2005-2007 (5.8%) but a reduction in LOS between the periods 2002-2004 (4.1 ± 2.0 days) and 2005-2007 (3.8 ± 1.7 days).The most common causes for readmission were cardiac-related. A reduction in LOS was not associated with an increase in the readmission rate in this sample. Optimization of cardiac status before discharge and routine primary care physician followup may lead to lower readmission rates.

    View details for DOI 10.1007/s11999-011-1957-0

    View details for Web of Science ID 000298103100021

    View details for PubMedID 21720934

    View details for PubMedCentralID PMC3237965

  • Readmission and Length of Stay After Total Hip Arthroplasty in a National Medicare Sample JOURNAL OF ARTHROPLASTY Vorhies, J. S., Wang, Y., Herndon, J., Maloney, W., Huddleston, J. I. 2011; 26 (6): 119-123


    Evaluation of hospital readmissions after total hip arthroplasty may help improve patient safety and cost reduction. This study investigates the rates and reasons for readmission as well as length of hospital stay (LOS) for 1802 total hip arthroplasty patients from 2002 to 2007. Data were abstracted from the Medicare Patient Safety Monitoring System. The overall 30-day rate of readmission was 6.8%. There was no difference in readmission rate from 2002 to 2004 (7.1%) to 2005 to 2007 (6.3%) (odds ratio, 0.90; 95% confidence interval, 0.63-1.30; P = .58). The overall mean LOS was 4.2 ± 2.2 days. There was a significant reduction in LOS from 2002 to 2004 (4.4 ± 2.5 days) to 2005 to 2007 (3.8 ± 1.7 days) (odds ratio, 1.28; 95% confidence interval, 1.25-1.31; P < .0001). The most common causes for readmission were cardiac related. A reduction in LOS was not associated with an increase in the rate of readmission in this sample. Efforts to optimize cardiac status before discharge may lead to lower rates of readmission in the future.

    View details for DOI 10.1016/j.arth.2011.04.036

    View details for Web of Science ID 000294393000023

    View details for PubMedID 21723700

  • siRNA Versus shRNA for Personalized Cancer Therapy: Mechanisms and Applications GENE-BASED THERAPIES FOR CANCER Vorhies, J. S., Rao, D. D., Senzer, N., Nemunaitis, J., Roth, J. A. 2010: 51–62
  • siRNA vs. shRNA: Similarities and differences ADVANCED DRUG DELIVERY REVIEWS Rao, D. D., Vorhies, J. S., Senzer, N., Nemunaitis, J. 2009; 61 (9): 746-759


    RNA interference (RNAi) is a natural process through which expression of a targeted gene can be knocked down with high specificity and selectivity. Using available technology and bioinformatics investigators will soon be able to identify relevant bio molecular tumor network hubs as potential key targets for knockdown approaches. Methods of mediating the RNAi effect involve small interfering RNA (siRNA), short hairpin RNA (shRNA) and bi-functional shRNA. The simplicity of siRNA manufacturing and transient nature of the effect per dose are optimally suited for certain medical disorders (i.e. viral injections). However, using the endogenous processing machinery, optimized shRNA constructs allow for high potency and sustainable effects using low copy numbers resulting in less off-target effects, particularly if embedded in a miRNA scaffold. Bi-functional design may further enhance potency and safety of RNAi-based therapeutics. Remaining challenges include tumor selective delivery vehicles and more complete evaluation of the scope and scale of off-target effects. This review will compare siRNA, shRNA and bi-functional shRNA.

    View details for DOI 10.1016/j.addr.2009.04.004

    View details for Web of Science ID 000267476800008

    View details for PubMedID 19389436

  • "Bifunctional" Short Hairpin RNA for Cancer Gene Therapy Rao, D. D., Wang, Z., Kumar, P., Yu, Y., Haddock, C., Vorhies, J., Tong, A. W., Maples, P. B., Senzer, N. N., Nemunaitis, J. NATURE PUBLISHING GROUP. 2009: S255
  • Microbial dissolution of clay minerals as a source of iron and silica in marine sediments NATURE GEOSCIENCE Vorhies, J. S., Gaines, R. R. 2009; 2 (3): 221–25

    View details for DOI 10.1038/NGEO441

    View details for Web of Science ID 000264289900025

  • Nucleic acid aptamers for targeting of shRNA-based cancer therapeutics. Biologics : targets & therapy Vorhies, J. S., Nemunaitis, J. J. 2007; 1 (4): 367-376


    Aptamers are nucleic acid ligands which have been validated to bind to epitopes with a specificity similar to that of monoclonal antibodies. Aptamers have been primarily investigated for their direct function in terms of inhibition of protein targets; however, recent evidence gives reason to actively explore aptamers as targeting moieties for delivery of anticancer therapeutics. Many aptamers have been developed to bind to extracellular membrane domains of proteins overexpressed on cancer cells and have the potential to be modified for use in targeting cancer therapeutics. The use of DNA vector-based short hairpin RNA (shRNA) for RNA interference (RNAi) is a precise means for the disruption of target gene expression but its clinical usage in cancer is limited by obstacles related to delivery into cancer cells. Nucleic acid aptamers are attractive candidates for targeting of shRNA therapies. Their small size, ease of production and modification, and high specificity are valued attributes in comparison to other targeting moieties currently being tested. Here we review the development of aptamers directed to PSMA, Nucleolin, HER-3, RET, TN-C, and MUC1 and focus on their potential for use in targeting of shRNA-based cancer therapeutics.

    View details for PubMedID 19707307

    View details for PubMedCentralID PMC2721292

  • Proof concept for clinical justification of network mapping for personalized cancer therapeutics CANCER GENE THERAPY Nemunaitis, J., Senzer, N., Khalil, I., Shen, Y., Kumar, P., Tong, A., Kuhn, J., LaMont, J., Nemunaitis, M., Rao, D., Zhang, Y., Zhou, Y., Vorhies, J., Maples, P., Hill, C., Shanahan, D. 2007; 14 (8): 686-695


    To identify signature targets associated with patient-specific cancer lesions based on tumor versus normal tissue differential protein and mRNA coexpression patterns for the purpose of synthesizing cancer-specific customized RNA interference knockdown therapeutics. Analysis of biopsied tissue involved two-dimensional difference in-gel electrophoresis (2D-DIGE) analysis coupled with MALDI-TOF/TOF mass spectrometry for proteomic assessment. Standard microarray techniques were utilized for mRNA analysis. Priority was assigned to overexpressed protein targets with co-overexpressed genes with a high likelihood of functional nodal centrality in the cancer network as defined by the interactive databases BIND, HPRD and ResNet. HPLC-grade small interfering RNA (siRNA) duplexes were utilized to assess knockdown of target proteins in expressive cell lines as measured by western blot. Seven patients with metastatic cancer underwent biopsy. One patient (RW001) had biopsies from two disease sites 10 months apart. Seven priority proteins were identified, one for each patient (RACK 1, Ras related nuclear protein, heat-shock 27 kDa protein 1, superoxide dismutase, enolase1, stathmin1 and cofilin1). Prioritized proteins in RW001 from the two disease sites over time were the same. We demonstrated >80% siRNA inhibition of RACK 1 and stathmin1 of inexpressive malignant cell lines with correlated cell kill. Identification of functionally relevant target gene fingerprints, unique to an individual's cancer, is feasible 'at the bedside' and can be utilized to synthesize siRNA knockdown therapeutics. Further animal safety testing followed by clinical study is recommended.

    View details for DOI 10.1038/sj.cgt.7701057

    View details for Web of Science ID 000248146500002

    View details for PubMedID 17541424

  • 10-year follow-up of gene-modified adenoviral-based therapy in 146 non-small-cell lung cancer patients CANCER GENE THERAPY Nemunaitis, J., Vorhies, J. S., Pappen, B., Senzer, N. 2007; 14 (8): 762-763

    View details for DOI 10.1038/sj.cgt.7701048

    View details for Web of Science ID 000248146500010

    View details for PubMedID 17514194

  • Nonviral delivery vehicles for use in short hairpin RNA-based cancer therapies EXPERT REVIEW OF ANTICANCER THERAPY Vorhies, J. S., Nemunaitis, J. 2007; 7 (3): 373-382


    The use of DNA vector-based short hairpin (sh)RNA for RNA interference shows promise as a precise means for the disruption of gene expression to achieve a therapeutic effect. The in vivo usage of shRNA therapeutics in cancer is limited by obstacles related to effective delivery into the nuclei of target cancer cells. Nonviral delivery vehicles that are relevant for shRNA delivery into humans belong to a group of substances about which significant preclinical data has been amassed to show an acceptable safety profile, resistance to immune defenses and good transfection efficiency. Here, we review the most promising current nonviral gene delivery vehicles with a focus on their potential use in cancer shRNA therapeutics.

    View details for DOI 10.1586/14737140.7.3.373

    View details for Web of Science ID 000245134900015

    View details for PubMedID 17338656