Nicholas Branch Allen

Mr. Nicholas Branch Allen

orcid

Research Focus & Metrics

Academic Career Length

7Years (2020-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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24 February 2022 in Foot & Ankle International
Verified
Journal Article
Closed access
BABijan Abar
Bijan Abar
NKNicholas Kwon
Nicholas Kwon
NANicholas Branch Allen
Nicholas Branch Allen
TLTrent Lau
Trent Lau
LJLindsey G. Johnson
Lindsey G. Johnson
SASamuel B. Adams
Samuel B. Adams
Background: Treating critically sized defects (CSDs) of bone remains a significant challenge in foot and ankle surgery. Custom 3D-printed implants are being offered to a small but growing subset of patients as a salvage procedure in lieu of traditional alternates such as structural allografts after the patient has failed prior procedures. The long-term outcomes of 3D-printed implants are still unknown and understudied because of the limited number of cases and short follow-up durations. The purpose of this study was to evaluate the outcomes of patients who received custom 3D-printed implants to treat CSDs of the foot and ankle in an attempt to aid surgeons in selecting appropriate surgical candidates. Methods: This was a retrospective study to assess surgical outcomes of patients who underwent implantation of a custom 3D-printed implant made with medical-grade titanium alloy powder (Ti-6Al-4V) to treat CSDs of the foot and ankle between June 1, 2014, and September 30, 2019. All patients had failed previous nonoperative or operative management before proceeding with treatment with a custom 3D-printed implant. Univariate and multivariate odds ratios (ORs) of a secondary surgery and implant removal were calculated for perioperative variables. Results: There were 39 cases of patients who received a custom 3D-printed implant with at least 1 year of follow-up. The mean follow-up time was 27.0 (12-74) months. Thirteen of 39 cases (33.3%) required a secondary surgery and 10 of 39 (25.6%) required removal of the implant because of septic nonunion (6/10) or aseptic nonunion (4/10). The mean time to secondary surgery was 10 months (1-22). Multivariate logistic regression revealed that patients with neuropathy were more likely to require a secondary surgery with an OR of 5.76 ( P = .03). Conclusion: This study demonstrated that 74% of patients who received a custom 3D-printed implant for CSDs did not require as subsequent surgery (minimum of 1-year follow-up). Neuropathy was significantly associated with the need for a secondary surgery. This is the largest series to date demonstrating the efficacy of 3D-printed custom titanium implants. As the number of cases using patient-specific 3D-printed titanium implant increases, larger cohorts of patients should be studied to identify other high-risk groups and possible interventions to improve surgical outcomes. Level of Evidence: Level IV, case series.

2 October 2020 in 3D Printing in Medicine
Verified
Journal Article
Open access
PDF file
RKRishin J. Kadakia
Rishin J. Kadakia
CWColleen M. Wixted
Colleen M. Wixted
NANicholas Branch Allen
Nicholas Branch Allen
AHAndrew E. Hanselman
Andrew E. Hanselman
SASamuel Adams
Samuel Adams
Background: Three dimensional printing has greatly advanced over the past decade and has made an impact in several industries. Within the field of orthopaedic surgery, this technology has vastly improved education and advanced patient care by providing innovating tools to complex clinical problems. Anatomic models are frequently used for physician education and preoperative planning, and custom instrumentation can assist in complex surgical cases. Foot and ankle reconstruction is often complicated by multiplanar deformity and bone loss. 3D printing technology offers solutions to these complex cases with customized implants that conform to anatomy and patient specific instrumentation that enables precise deformity correction. Case presentation: The authors present four cases of complex lower extremity reconstruction involving segmental bone loss and deformity – failed total ankle arthroplasty, talus avascular necrosis, ballistic trauma, and nonunion of a tibial osteotomy. Traditional operative management is challenging in these cases and there are high complication rates. Each case presents a unique clinical scenario for which 3D printing technology allows for innovative solutions. Conclusions: 3D printing is becoming more widespread within orthopaedic surgery. This technology provides surgeons with tools to better tackle some of the more challenging clinical cases especially within the field of foot and ankle surgery.

11 December 2020 in Journal of Bone and Joint Surgery
Verified
Journal Article
Closed access
DCDaniel J. Cunningham
Daniel J. Cunningham
JSJohn R. Steele
John R. Steele
NANicholas Branch Allen
Nicholas Branch Allen
JNJames A. Nunley
James A. Nunley
SASamuel Adams
Samuel Adams
Background: Preoperative mental health and depression have been shown to negatively impact patient-reported outcome measures after a broad array of orthopaedic procedures including total ankle arthroplasty. The hypothesis for this study was that decreased Short Form (SF)-36 Mental Component Summary (MCS) scores will modulate the impact of depression on patient-reported outcome measures after total ankle arthroplasty. Methods: All patients undergoing primary total ankle arthroplasty between January 2007 and December 2016 who were enrolled into a prospective outcomes study and who had at least 1-year minimum study follow-up were retrospectively reviewed. Patients were separated into 4 groups based on the presence or absence of an SF-36 MCS score of <35 points and diagnosis of depression. SF-36 Physical Component Summary (PCS) and MCS scores, Short Musculoskeletal Function Assessment (SMFA) function and bother components, and visual analog scale (VAS) pain were collected preoperatively and in the 1 to 2-year follow-up. The Wilcoxon rank sum was used to assess differences in outcomes by depression and low preoperative MCS scores. Multivariable models were then constructed to evaluate between-group differences in change scores according to preoperative SF-36 MCS scores and a diagnosis of depression, with adjustment for baseline patient and treatment characteristics. Results: Patients with depression and those with low preoperative MCS scores had significantly worse final outcome scores along with reduced improvement in SF-36 PCS and VAS pain scores compared with patients without these risk factors. Among patients with depression, low preoperative MCS scores helped to differentiate patients with poor final outcome scores. Similarly, in patients with low preoperative MCS scores, depression helped to differentiate patients with poor final outcome scores. Conclusions: Although patients achieved significant improvements in functional outcomes regardless of cohort, decreased preoperative mental health modulated the impact of depression on outcomes. Patients with diminished preoperative mental health and depression are at an increased risk for sustaining smaller improvements in outcomes. Level of Evidence: Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

27 June 2025 in Bioengineering
Verified
Journal Article
Open access
PDF file
.S.Kush Savsani
.Kush Savsani
AAAlexandra Hunter Aitchison
Alexandra Hunter Aitchison
NANicholas Branch Allen
Nicholas Branch Allen
EAElsie A. Adams
Elsie A. Adams
SASamuel Adams
Samuel Adams
Cartilage injuries, due to their limited regenerative capacity, often result in chronic pain and functional impairment. These injuries are difficult to manage with conventional surgical repair techniques; therefore, alternative treatments are necessary. Gelatin methacrylate (GelMA) has emerged as a promising biomaterial for cartilage tissue engineering due to its biocompatibility, tunable mechanical properties, and ability to be used in advanced applications like 3D bioprinting. This review examines the synthesis, properties, and limitations of GelMA in cartilage repair, focusing on its applications in 3D bioprinting for the creation of patient-specific cartilage constructs. It also highlights preclinical studies exploring the potential of GelMA-based scaffolds in various animal models. Despite its advantages, challenges remain, such as the mechanical limitations of GelMA and its degradation rate in dynamic environments. Hybrid scaffolds, in situ bioprinting, and personalized bioinks offer solutions to these issues. Ultimately, long-term clinical trials are needed to assess the durability and efficacy of GelMA-based scaffolds in human applications. Future research is aimed at overcoming these challenges, improving the mechanical strength of GelMA scaffolds, and enhancing their clinical translation for cartilage repair.

11 February 2022 in Journal of 3D Printing in Medicine
Verified
Journal Article
Closed access
KBKier Maddox Blevins
Kier Maddox Blevins
RDRichard Danilkowicz
Richard Danilkowicz
AFAmanda N Fletcher
Amanda N Fletcher
NANicholas Branch Allen
Nicholas Branch Allen
LJLindsey G Johnson
Lindsey G Johnson
SASamuel B Adams
Samuel B Adams
Annually, millions of Americans require some form of reconstructive surgery as the result of a traumatic injury, degenerative process or pathologic state. In the field of orthopedic surgery, the go...

14 December 2024 in Gels
Verified
Journal Article
Open access
PDF file
AAAlexandra Hunter Aitchison
Alexandra Hunter Aitchison
NANicholas Branch Allen
Nicholas Branch Allen
KMKishen Mitra
Kishen Mitra
BABijan Abar
Bijan Abar
COConor O'Neill
Conor O'Neill
SASamuel Adams
Samuel Adams
This study investigates 3D extrusion bioinks for cartilage tissue engineering by characterizing the physical properties of 3D-printed scaffolds containing varying alginate and polyvinyl alcohol (PVA) concentrations. We systematically investigated the effects of increasing PVA and alginate concentrations on swelling, degradation, and the elastic modulus of printed hydrogels. Swelling decreased significantly with increased PVA concentrations, while degradation rates rose with higher PVA concentrations, underscoring the role of PVA in modulating hydrogel matrix stability. The highest elastic modulus value was achieved with a composite of 5% PVA and 20% alginate, reaching 0.22 MPa, which approaches that of native cartilage. These findings demonstrate that adjusting PVA and alginate concentrations enables the development of bioinks with tailored physical and mechanical properties, supporting their potential use in cartilage tissue engineering and other biomedical applications.