Joseph T. Patterson

Tissue-engineered vascular grafts for use in the treatment of congenital heart disease: from the bench to the clinic and back again.

Since the first tissue-engineered vascular graft (TEVG) was implanted in a child over a decade ago, growth in the field of vascular tissue engineering has been driven by clinical demand for improved vascular prostheses with performance and durability similar to an autologous blood vessel. Great strides were made in pediatric congenital heart surgery using the classical tissue engineering paradigm, and cell seeding of scaffolds in vitro remained the cornerstone of neotissue formation. Our second-generation bone marrow cell-seeded TEVG diverged from tissue engineering dogma with a design that induces the recipient to regenerate vascular tissue in situ. New insights suggest that neovessel development is guided by cell signals derived from both seeded cells and host inflammatory cells that infiltrate the graft. The identification of these signals and the regulatory interactions that influence cell migration, phenotype and extracellular matrix deposition during TEVG remodeling are yielding a next-generation TEVG engineered to guide neotissue regeneration without the use of seeded cells. These developments represent steady progress towards our goal of an off-the-shelf tissue-engineered vascular conduit for pediatric congenital heart surgery.

Photodegradation as a mechanism for controlled drug delivery

A drug‐releasing model compound based on photosensitive acrylated ortho‐nitrobenzylether (o‐NBE) moiety and fluorescein was synthesized to demonstrate photolysis as a mechanism for drug release. Release of this model compound from a hydrogel network can be controlled with light intensity (5–20 mW/cm2), exposure duration (0–20 min) and wavelength (365, 405, 436 nm). Due to the high molar absorptivity of the compound (5,984 M−1 cm−1), light attenuation is significant in this system. Light attenuation can be used to self‐limit the dosing from a hydrogel, and allow subsequent release from the drug reservoir after equilibration, or attenuation can be utilized to create a chemical gradient within the hydrogel. A model of photodegradation that uses an integrated form of Beer–Lamberts law quantitatively predicts release from hydrophilic hydrogels with low crosslink density, but fails to quantitatively predict release from more hydrophobic systems, presumably due to partitioning of the hydrophobic model compound in the hydrogel. In contrast to other mechanisms of release (enzymolysis, hydrolysis), photolysis provides real‐time on demand control over drug release along with the unique ability to create chemical gradients within the hydrogel. Biotechnol. Bioeng. 2010;107: 1012–1019.

TGFβR1 Inhibition Blocks the Formation of Stenosis in Tissue-Engineered Vascular Grafts

We previously developed a tissue-engineered vascular graft (TEVG), created by seeding a biodegradable scaffold with autologous bone marrow–derived mononuclear cells, specifically designed for use in congenital heart surgery. We demonstrated in a clinical trial that this approach is safe and

Volar plate fixation of recalcitrant scaphoid nonunions with volar carpal artery vascularized bone graft

Chronic scaphoid fracture nonunion continues to present a significant challenge to the treating orthopedic surgeon. Internal fixation with threaded compression screws leads to high union rates, and is currently the gold standard, but there are certainly circumstances where a scaphoid screw does not provide the stability necessary for nonunion repair. Results using a volar buttress plate have been promising, but have not been described in conjunction with the use of vascularized bone graft. Vascularized bone grafts have been shown to be highly effective in achieving rapid and reproducible rates of union. We describe a novel combination of a vascularized volar distal radius wedge autograft pedicled on the volar carpal artery and volar buttress plating for salvage treatment of chronic scaphoid nonunion.

Analysis of coronary artery dosimetry in the 3-dimensional era: Implications for organ-at-risk segmentation and dose tolerances in left-sided tangential breast radiation

PURPOSE To evaluate the dose to the left anterior descending artery in patients receiving left-sided tangential breast radiation. METHODS AND MATERIALS The study cohort consisted of 50 left-sided breast cancer patients who were sequentially simulated at our institution. The heart and left anterior descending (LAD) artery were contoured from its origin on the left main coronary artery down to the last visible segment of the vessel. Detailed dosimetry of the heart and LAD artery were obtained and analyzed. RESULTS Excellent correlation between the dose to the heart and LAD artery was discovered. The mean LAD dose was 17.98 Gy. The mean dose to the proximal LAD was 2.46 Gy. The median V25 was 2.91% and the mean heart dose 3.10 Gy. For every 100 cGy increase in mean heart dose, mean LAD dose increased by 4.82 Gy. For every percent increase in the heart V10 and V25, there was a 2.23 Gy and 2.77 Gy increase in mean LAD dose, respectively. For every percent increase of heart V25, a 5.6% increase in the LAD V20 was demonstrated. CONCLUSIONS The LAD artery dose correlates very closely with all of the commonly measured heart dose constraints, and does not need to be contoured separately when standard tangential borders are used. Incidental LAD artery doses remain with supine breast tangential radiation therapy.

Prior Lumbar Spinal Arthrodesis Increases Risk of Prosthetic-Related Complication in Total Hip Arthroplasty.

BACKGROUND Degenerative hip disorders often coexist with degenerative changes of the lumbar spine. Limited data on this patient population suggest inferior functional improvement and pain relief after surgical management. The purpose of this study is to compare the rates of prosthetic-related complication after primary total hip arthroplasty (THA) in patients with and without prior lumbar spine arthrodesis (SA). METHODS Medicare patients (n = 811,601) undergoing primary THA were identified and grouped by length of prior SA (no fusion, 1-2 levels fused [S-SAHA], and ≥3 levels fused [L-SAHA]). RESULTS Compared with controls, patients with prior SA had significantly higher rates of complications including dislocation (control: 2.36%; S-SAHA: 4.26%; and L-SAHA: 7.51%), revision (control: 3.43%, S-SAHA: 5.55%, and L-SAHA: 7.77%), loosening (control: 1.33%, S-SAHA: 2.10%, and L-SAHA: 3.04%), and any prosthetic-related complication (control: 7.33%, S-SAHA: 11.15% [relative risk: 1.52], and L-SAHA: 14.16% [relative risk: 1.93]) within 24 months (P < .001). CONCLUSION The interplay of coexisting degenerative hip and spine disease deserves further attention of both arthroplasty and spine surgeons.

The James A. Rand Young Investigator's Award: Administrative Claims vs Surgical Registry: Capturing Outcomes in Total Joint Arthroplasty

BACKGROUND Administrative claims in total joint arthroplasty are used for observational studies and payment adjustments under the Comprehensive Care for Joint Replacement (CJR) legislation. Claims data have not been validated against prospective surgical outcome registries for primary total hip (THA) or knee arthroplasty (TKA). We hypothesized that significant differences in reported comorbidity and adverse event measures exist between administrative claims and prospective registry data relevant to payment adjudication under the CJR reimbursement model. METHODS Comorbidities and outcomes in primary TKA and THA in the United Healthcare and Medicare Standard Analytical File 5% Sample insurance claims datasets (PearlDiver Technologies, Inc) were compared to age-matched cohorts from the National Surgical Quality Improvement Program (ACS-NSQIP) surgical outcomes data from 2007 to 2011 using comparable International Classification of Diseases, Ninth Revision, Clinical Modification and Current Procedural Terminology codes at 30, 90, and 360 days from index arthroplasty. Pearsons chi-square test was used for statistical analyses. RESULTS The total study population included 93,953 primary THA and 176,944 TKA patients. Primary TKA and THA patients in insurance claims cohorts had significantly fewer reported comorbidities, higher rates of surgical site infection, pulmonary embolism, wound dehiscence, thromboembolic events, and neurologic deficits, and lower reported rates of revision surgery than ACS-NSQIP cohorts within 30 days of primary TKA and THA. Cumulative incidence of adverse events increased significantly from 30 to 360 days after primary arthroplasty. CONCLUSION We report significant discordance in the prevalence of patient comorbidities and incidence of adverse events in primary THA and TKA between ACS-NSQIP and the administrative claims data of Medicare and United Healthcare. These disparities have implications for observational outcome studies as well as payment adjudication under the CJR reimbursement model in total joint arthroplasty.

Predicting Radiographic Changes at the First Visit Following Operative Repair of Distal Radius Fractures

PURPOSE To test the hypothesis that clinical assessment reliably identifies patients with radiographic changes (including loss of reduction, hardware failure, and hardware migration) at the initial visit following operative repair of distal radius fractures. METHODS We identified 102 patients undergoing operative repair of distal radius fractures. Radiographs and clinical notes were reviewed. RESULTS At the initial postoperative visit, 11 patients had more than normal postoperative pain, 0 had deformity, 0 had crepitus with gentle motion, and 0 had instability at the fracture site on examination. These 11 patients were considered to have positive clinical assessments, but none had radiographic changes on x-rays taken that day. Three patients had negative clinical assessments but had radiographic changes noted at the initial postoperative visit. There were no additional radiographic changes between the series taken at the initial postoperative visit and series taken at later postoperative visits. CONCLUSIONS These data suggest that for purposes of detecting radiographic changes, radiography at the initial visit is helpful, whereas radiography at subsequent visits may not be. Radiography at subsequent visits may be useful to monitor bony healing, which we did not investigate.

Isolated avulsion fracture at the medial head of the gastrocnemius muscle

An isolated avulsion fracture involving the femoral origin of the medial head of the gastrocnemius muscle without an associated muscular, meniscal, or ligamentous injury is extremely rare. We report a case of a 14-year-old male wrestler who presented with a radiographically occult avulsion fracture of the medial gastrocnemius tendon sustained during competition. To our knowledge, this is the first case to describe a mechanism of injury as well as to report a return to competition after non-operative management.

Routine imaging after operatively repaired distal radius and scaphoid fractures: a survey of hand surgeons.

Background There is currently no standard of care for imaging after hand and upper-extremity procedures, and current imaging practices have not been characterized. Questions/Purposes To characterize current imaging practices and to compare those practices to the best available evidence. Patients and Methods A survey was distributed to attending-level surgeons at a regional hand and upper-extremity surgery conference in the United States in 2013. 40 out of 75 surgeons completed the survey (53%). Results All results are presented for distal radius and scaphoid fractures, respectively. There was a high degree of variability between respondents in the number of radiographic series routinely ordered during follow-up of asymptomatic patients, with the number of series ranging from 1-6 and 1-6. On average, respondents did not order an excessive number of follow-up radiographs for asymptomatic patients, with means (± standard deviations) of 2.6 ± 1.0 and 3.3 ± 1.2 radiographic series. Radiographic series were taken at only 74% and 81% of postoperative visits with asymptomatic patients. Only 10% and 8% of respondents felt it was acceptable medical practice to save costs by ordering postoperative radiographs only when patients are symptomatic. Conclusions Among a sample of 40 fellowship-trained hand surgeons, these findings demonstrate a high degree of variability in number of radiographs obtained after operative repair of distal radius and scaphoid fractures. On average, respondents were relatively efficient with respect to total number of postoperative radiographs ordered. Level of Evidence Diagnostic study, level IV.