About

Patrick J. Cahill, MD, is a Professor of Orthopaedic Surgery at the Children's Hospital of Philadelphia. He holds a B.S. in Mathematics from Vanderbilt University and an M.D. from the University of Illinois College of Medicine. His professional focus is on pediatric orthopaedics, with research contributions spanning various aspects of spinal deformities, scoliosis, and related surgical outcomes. Dr. Cahill has authored numerous studies on topics such as chest wall motion in scoliosis, postoperative complications in cerebral palsy patients, development of best practice guidelines for pediatric spinal deformity care, and the effects of surgical interventions on pediatric patients. His work emphasizes understanding the developmental changes and surgical impacts on children with spinal conditions, contributing to improved clinical practices and patient outcomes.

Research topics

• Medicine
• Surgery
• Orthodontics
• Physical therapy
• Nuclear medicine

Selected publications

• A Reflection of Trends Across Modern Academia

  Journal of Bone and Joint Surgery · 2026-05-01

  article1st authorCorresponding
  PublisherDOI

• Clinical evaluation of ThecaFlex DRx, a novel implantable catheter-port for intrathecal nusinersen delivery in spinal muscular atrophy: Initial results from the PIERRE–IDE study

  Journal of Neuromuscular Diseases · 2026-03-13

  articleOpen access

  BACKGROUND: Administration of Nusinersen requires repeated lumbar intrathecal access, posing challenges for patients with Spinal Muscular Atrophy (SMA). A purpose-built system may streamline drug delivery. OBJECTIVE: To assess the feasibility and safety of ThecaFlex DRx for intrathecal Nusinersen dosing. METHODS: We present initial results of a prospective, multicenter investigational device exemption (IDE) study. Patients with SMA who had an indication for intrathecal Nusinersen were enrolled. Primary outcomes were successful system implantation and postoperative infusion. Prespecified safety outcomes consisted of adverse events adjudicated for severity and device or procedure relatedness. RESULTS: Twenty-five subjects underwent device implantation. Median age at implantation was 13.8 years (IQR 10.0-18.0), and 52% were female. Subjects included individuals with SMA types I (16%), II (64%), and III (20%). Implantation was successful in all cases. At the interim data cutoff, median follow-up was 230 days (IQR 76.0-369.0) at which point 23 subjects (92%) had successfully received Nusinersen infusions. Ten patients reached one year of follow-up, and all of them maintained a functional device at this visit. Sixty adverse events occurred in 19 subjects, with 12 events (20%) adjudicated as serious adverse events that were most commonly wound-related or respiratory. At one year, the estimated probability of remaining free from device action was 86.2% (95% CI 0.73-1.00), with two devices requiring explantation due to wound dehiscence and access difficulties, respectively. CONCLUSIONS: This interim report supports the feasibility of ThecaFlex DRx for Nusinersen administration, with long-term durability and effectiveness to be defined with longer follow-up.For more information about the PIERRE study (NCT05866419), visit: https://www. CLINICALTRIALS: gov/study/NCT05866419.

  PublisherDOI

• Breathing pattern integration in 4D-MRI analysis: a technical framework for pediatric thoracic insufficiency syndrome assessment

  2026-04-01

  article

  We present a technical framework for integrating breathing frequency into regional volumetric analysis of free-breathing 4D dynamic MRI in pediatric populations. Regional quantitative MRI endpoints traditionally focused on tidal volume amplitudes but did not capture breathing rate, which varies substantially with age and respiratory state. We describe implementation of frequency normalized regional metrics (RR/TV ratios) alongside standard regional volumetric measures, using Z-score standardization against age-matched reference data. This approach is demonstrated in 47 pediatric thoracic insufficiency syndrome (TIS) patients with paired pre/post-VEPTR surgery scans, compared to 200 healthy controls. Technical components include respiratory rate derived during 4D reconstruction via the OFx method, regional volumetry of lung compartments, and reference space normalization using the Virtual Growing Child (VGC) normative database. We show that frequency weighted outcomes exhibit stronger developmental trends (Spearman ρ = -0.54 for lung RR/TV vs. +0.40 to +0.44 for lung volumes) and larger effect sizes when tracking surgical changes (r = 0.54–0.64 for RR/TV vs. r = 0.66–0.83 for TV). The framework can be integrated into existing 4D-MRI pipelines with minimal overhead and provide a more complete characterization of breathing mechanics in pediatric chest wall disorders.

  PublisherDOI

• Vertical Expandable Prosthetic Titanium Rib

  2026-01-01

  book-chapterSenior author
  PublisherDOI

• Coupling maps for visualizing chest wall-diaphragm coordination in pediatric thoracic insufficiency syndrome from 4D dynamic MRI

  2026-02-13

  article
  PublisherDOI

• Spinal Deformity in Congenital Myopathies

  Indian Spine Journal · 2026-05-01

  articleOpen accessSenior author

  Abstract Congenital myopathy (CM) is a group of rare genetic disorders characterized by hypotonia, hyporeflexia, and weakness present at birth. The condition is estimated to affect between 0.7 and 4.4 per 100,000 children. Synthesizing physical exam findings, magnetic resonance imaging results, muscle biopsy morphology, and genetic testing results is necessary to reach a specific CM sub-diagnosis. Major forms of CM include nemaline myopathy, core myopathies, and centronuclear myopathies. CM diagnoses can lead to the onset of scoliosis as well as a host of other neurological, cardiological, and pulmonological comorbidities. Patients often are required to consult a wide variety of clinical specialties to obtain appropriate care for this condition. Orthopedic pathologies, including congenital hip dysplasia, ligamentous laxity, and early onset scoliosis (EOS), are common in CM patients. EOS is particularly severe in SEPN1 - and ryanodine receptor ( RYR1) -related myopathies, often necessitating nighttime respiratory support and surgical correction. While not many patients diagnosed with CM will require surgical intervention, research indicates that outcomes following surgery are similar for patients with other neuromuscular conditions across growth-friendly (GF) techniques like vertical expander prosthetic titanium rib, traditional growing rods, and magnetically controlled growing rods. Further investigation is needed to understand the full risk profile of performing surgery in patients with congenital myopathies.

  PublisherDOI

• Comparative analysis of thoracic structure and function using CT and dynamic MRI in pediatric thoracic insufficiency syndrome with and without neuromuscular disease

  Spine Deformity · 2025-05-06

  article
  PublisherDOI

• Coronal and Sagittal Balance Following Posterior Spinal Fusion for Adolescent Idiopathic Scoliosis

  Journal of Bone and Joint Surgery · 2025-07-25

  article

  BACKGROUND: Achieving and maintaining global spinal balance is a crucial goal in posterior spinal fusion for adolescent idiopathic scoliosis (AIS). Despite its substantial impact on operative success, there is a noticeable gap in the literature regarding a systematic evaluation of the trajectory and durability of this critical parameter. With this study, we aimed to characterize the evolution of global balance after posterior spinal fusion for AIS. METHODS: A prospective, multicenter spinal deformity database was retrospectively queried for patients with AIS undergoing posterior spinal fusion. Standing, 2-view radiographs (anteroposterior and lateral) were obtained at the first-erect visit, 6 months, 1 year, 2 years, and 5 years, with a subset of patients having radiographs at the 10-year mark. Coronal balance was defined as the difference, in centimeters, between the C7 plumb line and the central sacral vertical line (CSVL). The sagittal vertical axis (SVA) measured sagittal balance, calculated as the difference, in centimeters, between the C7 plumb line and the posterosuperior corner of the superior end plate of S1. RESULTS: The study included 477 patients with 5 years of follow-up and 84 patients with a decade of follow-up. The mean patient age was 14.1 years, 67.9% of the patients were White, and 81.6% of the patients were female. Preoperative assessment revealed that 50.7% of the patients demonstrated optimal global balance. The initial postoperative evaluation showed essentially no improvement, with only 55.6% achieving optimal balance (Coronal and Sagittal Harmony [CASH] A0) at the first-erect visit. Subsequent follow-up demonstrated steady improvement, with 81.8% reaching optimal balance at 5 years and 87.7% at the 10-year mark. CONCLUSIONS: This study offers a comprehensive analysis of global spinal alignment and traces the balance trajectory (in both the coronal and sagittal planes) after posterior spinal fusion in AIS. To our knowledge, it is the largest and longest follow-up study of its kind. The findings highlight a profound and steady postoperative improvement in global balance over time, advancing our understanding of postoperative spinal balance in AIS. The novel CASH classification introduced here serves as a possible tool for evaluating overall alignment and balance in patients with AIS. LEVEL OF EVIDENCE: Therapeutic Level III . See Instructions for Authors for a complete description of levels of evidence.

  PublisherDOI

• Stress-relaxation and Failure Properties of Spinal Ligaments in Pigs with and without Scoliosis-like Deformity

  Journal of Biomechanical Engineering · 2025-08-11

  articleOpen access

  This study addresses the need for accurate tissue material properties in computational models of the spine. Fundamental to functional spinal unit (FSU) biomechanics are the stress-relaxation and failure properties of the interspinous and intertransverse ligaments (ISL and ITL, respectively). These were measured and compared in normative and scoliotic spines using a Yorkshire pig model. Skeletally immature female pig spines were posterolaterally tethered to induce scoliosis. 23 ISLs and 17 ITLs excised from normative and scoliotic spine segments underwent stress-relaxation and failure tests. Group comparisons tested the effects of scoliosis (magnitude, convexity versus concavity), spinal level (thoracic, lumbar), and pig age. Scoliosis altered ligament geometry and material behavior. The cross-sectional area of concave ITLs was greater than that of normative ITLs, which was larger than that of convex ITLs. ISL and ITL elastic moduli varied across groups. Scoliotic ISL failure strain was higher than that of the normative ISL, and convex ITL failure strain was higher than that of the normative ITL. The long-term relaxation time of ISLs from scoliotic FSUs was longer than that of normative ISLs. These findings demonstrate differences in dimensions and stress-relaxation, and failure material properties of the ISL and ITL associated with scoliosis. Obtained values were comparable to reported human and porcine ligament material properties and were incorporated into an FSU finite element model and shown to affect range of motion. Such property differences may inform quantification of ligament properties with higher sample sizes, related surgical techniques, and further computational modeling.

  PublisherOA PDFDOI

• Auto‐segmentation of thoraco‐abdominal organs in pediatric dynamic MRI

  Medical Physics · 2025-11-01 · 2 citations

  articleOpen access

  PURPOSE: Dynamic magnetic resonance imaging (dMRI) is a practical imaging modality for capturing information about regional thoracic-abdominal components and their dynamics in healthy children and pediatric patients with thoracic insufficiency syndrome (TIS). We propose an auto-segmentation set-up for the lungs, kidneys, liver, spleen, and thoraco-abdominal skin outer boundary (Skn) in dMRI images. METHODS: with 6.00 mm spacing between slices. We utilized images from 89 and 10 subjects at end inspiration for training and validation, respectively. For testing, we experimented with three scenarios utilizing: (1) the images of the 90 (=189-89-10) remaining subjects at end inspiration for testing, (2) the images of the remaining 90 subjects at end expiration for testing, and (3) the images of the other 99 (=89+10) subjects at end expiration for testing. In some situations, we can take advantage of the already available ground truth (GT) segmentation for an object in a subject at a particular respiratory phase to automatically segment the same object in the same subject at a different respiratory phase, and then refine the segmentation to create the final GT for all respiratory phases in the image of a subject. We anticipate that this process of creating GT would require minimal post hoc correction. In this spirit, we conducted separate experiments where we assumed to have GT of test subjects at the end expiration for scenario (1), end inspiration for (2), and end inspiration for (3). A major contribution in this paper is the different scenarios of training and testing that we have extensively evaluated with respect to respiratory phases and the subjects to which the images in the training and testing sets belong. RESULTS: Among these three scenarios of testing, for DL-R, we achieve the best average location error (LE) of about 1 voxel for the lungs, kidneys, and spleen, and 1.5 voxels for the liver and Skn. The standard deviation (SD) of LE is about 1 or 2 voxels. For DL-D, we achieve an average Dice coefficient (DC) of about 0.92 to 0.94 for the lungs, 0.82 for the kidneys, 0.90 for the liver, 0.81 for the spleen, and 0.93 for Skn. The SD of DC is lower (0.02 to 0.07) for the lungs, liver, and Skn and slightly higher (0.06 to 0.12) for the spleen and kidneys. CONCLUSIONS: Motivated by applications in surgical planning for disorders such as TIS, adolescent idiopathic scoliosis, and early onset scoliosis, we have created an auto-segmentation system for thoraco-abdominal organs in dMRI acquisitions. This proposed setup copes with the challenges posed by low resolution, motion blur, inadequate contrast, and image intensity non-standardness in dMRI images quite well.

  PublisherOA PDFDOI

Frequent coauthors

• Suken A. Shah

  155 shared

• Amer F. Samdani

  Shriners Hospitals for Children - Philadelphia

  150 shared

• Paul D. Sponseller

  Stryker (United States)

  148 shared

• Michael G. Vitale

  Morgan Stanley Children's Hospital

  118 shared

• Peter O. Newton

  Rady Children's Hospital-San Diego

  109 shared

• Randal R. Betz

  105 shared

• Burt Yaszay

  Seattle Children's Hospital

  92 shared

• Daniel J. Miller

  Gillette Children's Specialty Healthcare

  92 shared

Education

• Fellow, Orthopedic Surgery

  Rush University Medical Center

  2007

• Resident, Orthopedic Surgery and Sports Medicine

  Loyola Medicine

  2006

• MD, College of Medicine

  University of Illinois at Chicago

  2001

• Pre-Intramural Research Training Award Fellow, NIDCD

  National Institutes of Health

  1997

• BS, College of Arts and Sciences

  Vanderbilt University

  1996