AZAndrew S. Zhang

Andrew S. Zhang

*This is an algorithmically generated author record based on publicly available information.

Current Organizations / Institutes

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Previous Organizations / Institutes

The organizations / institutes from the scholar's other articles in the past ten years


Andrew S. Zhang has a total of 83 co-authors. Here are the top co-authors by number of shared publications:


Latest Publications

  • Consensus in Motion: Real-Time Insights From the SICCMII/ISASS 2025 Symposium on Endoscopic Spine Surgery

    by Kai-Uwe Lewandrowski, Gregory W. Basil, João Paulo Bergamaschi, Benedikt Burkhardt, Jose Cruz, Bambang Dewono, Raymond Gardocki, Saqib Hasan, Brian Kwon, Jun Ho Lee, et al.

  • Anterior Lumbar Interbody Fusion Implant Positioning in Relation to the Epiphyseal Rim

    by Jay Manuel, Madeline Gautreaux, Andrew S. Zhang, James Robinson, Milan Mody, Caroline Bsc Hannigan, Tunde Abubakar, Giovanni F. Solitro

    Study Design: Biomechanical study on bone surrogates reconstructed from cadaveric vertebrae. Objective: The goal of this study was to evaluate the influence of cage positioning on construct strength and to determine the relationship between the depth of the epiphyseal rim and subsidence load in anterior lumbar interbody fusion (ALIF). Summary of Background Data: Cage subsidence is a significant complication affecting fusion success with an incidence range of 6%–23%. Cage subsidence can result in chronic pain due to altered spine alignment, loss of intervertebral height, and inflammatory response. Reoperation rates can range from 5% to 20%. Understanding the impact of cage positioning and endplate characteristics on subsidence is crucial for optimizing surgical outcomes. Materials and Methods: Sixteen cadaveric (L3–L5) lumbar segments were utilized. Bone surrogates were prepared to represent the heterogeneous structure of lumbar vertebrae. Compression testing was performed using a cage, similar to the cages used in ALIF procedures, shaped indenter with 3 cage positioning configurations: maximized, partial, and null overlap with the epiphyseal rim. Construct stiffness and subsidence load were measured. Results: Cage positioning significantly influenced subsidence load ( P P =0.02). More specifically, cages with maximized epiphyseal contact demonstrated significantly higher subsidence loads than the others ( P =0.01). The thickness of the cortical bone was highly correlated with subsidence load when maximized epiphyseal rim contact was achieved ( R 2 = 0.83, P < 0.01). Conclusion: Placement of ALIF cages along the anterior epiphyseal rim increases construct strength. A correlation exists between the thickness of the epiphyseal rim and cage subsidence, suggesting potential preoperative estimation of subsidence load based on epiphyseal rim thickness.


  • Open Access

    Incidence and Outcomes of Vertebral Compression Fracture Among Patients Infected with COVID-19

    by Helen Zhang, Mariah Balmaceno-Criss, Abigail M. Fruge, Patrick A. Massey, Alan H. Daniels, Andrew S. Zhang

    Background/Objectives: Early studies have suggested that the SARS-CoV-2 virus has a deleterious effect on bone mineral density and may increase the risk of pathological fractures. This study characterized vertebral compression fractures in patients with and without a prior diagnosis of COVID-19. Methods: Using a nationwide claims database, this retrospective study used ICD-10 billing codes to identify patients with a diagnosis of vertebral compression fracture from January 2020 to April 2022. Two cohorts were created based on whether the patients had a concurrent diagnosis of COVID-19. Patient demographics, comorbidities, and outcome measures were characterized by descriptive analysis. Results: In total, 413,425 patients met the inclusion criteria. Among them, a total of 23,148 patients (5.60%) had a diagnosis of COVID-19 at the time of their compression fracture. Among the COVID-19 patients, the incidences of vertebral compression fracture were 0.42% in 2020 and 0.33% in 2021, in comparison to the historical average yearly incidence of 0.17% across all patients. The patients with COVID-19 at the time of compression fracture diagnosis had a higher rate of vitamin D deficiency (OR: 1.25) and a lower rate of routine healing (OR: 0.61). The patients without COVID-19 were more likely to be osteoporotic (OR: 0.88), experience additional compression fractures (OR: 0.38), and have kyphoplasty or vertebroplasty (OR: 0.73). Conclusions: Despite lower rates of osteoporosis, patients with a concomitant COVID-19 diagnosis exhibited a higher incidence of compression fractures. Although more research is needed, these results support increasing bone health surveillance in patients with a history of COVID-19 infection.


  • Cervical disc arthroplasty is safe across various obesity levels

    by Manjot Singh, Benjamin Chanes, Mariah Balmaceno-Criss, Alan H. Daniels, Andrew S Zhang


  • Coccydynia

    by Drayton Daily, James Bridges, William B. Mo, Andrew Z. Mo, Patrick Allan Massey, Andrew S Zhang

    » Coccydynia is a painful condition affecting many patients at the terminal caudal end of the spine. » An understanding of coccyx anatomy and variations of morphology is necessary for proper diagnosis. A multifactorial etiology for pain may be responsible for this clinical entity. » Several treatment options exist. Successful outcomes for patients depend on individual patient characteristics and the etiology of pain.


  • Open Access

    Impact of bone density and integrated screw configuration on standalone anterior lumbar interbody construct strength

    by Ross Dies, Jay Manuel, Andrew S. Zhang, Milan Mody, Seokgi Lee, Mathew Root, Trevor Carroll, Chukwuemeka Mbagwu, Giovanni F. Solitro


  • Top Cited Papers
    Open Access

    Comparison of ChatGPT–3.5, ChatGPT-4, and Orthopaedic Resident Performance on Orthopaedic Assessment Examinations

    by Patrick A. Massey, Carver Montgomery, Andrew S Zhang

    Introduction: Artificial intelligence (AI) programs have the ability to answer complex queries including medical profession examination questions. The purpose of this study was to compare the performance of orthopaedic residents (ortho residents) against Chat Generative Pretrained Transformer (ChatGPT)-3.5 and GPT-4 on orthopaedic assessment examinations. A secondary objective was to perform a subgroup analysis comparing the performance of each group on questions that included image interpretation versus text-only questions. Methods: The ResStudy orthopaedic examination question bank was used as the primary source of questions. One hundred eighty questions and answer choices from nine different orthopaedic subspecialties were directly input into ChatGPT-3.5 and then GPT-4. ChatGPT did not have consistently available image interpretation, so no images were directly provided to either AI format. Answers were recorded as correct versus incorrect by the chatbot, and resident performance was recorded based on user data provided by ResStudy. Results: Overall, ChatGPT-3.5, GPT-4, and ortho residents scored 29.4%, 47.2%, and 74.2%, respectively. There was a difference among the three groups in testing success, with ortho residents scoring higher than ChatGPT-3.5 and GPT-4 (P < 0.001 and P < 0.001). GPT-4 scored higher than ChatGPT-3.5 (P = 0.002). A subgroup analysis was performed by dividing questions into question stems without images and question stems with images. ChatGPT-3.5 was more correct (37.8% vs. 22.4%, respectively, OR = 2.1, P = 0.033) and ChatGPT-4 was also more correct (61.0% vs. 35.7%, OR = 2.8, P < 0.001), when comparing text-only questions versus questions with images. Residents were 72.6% versus 75.5% correct with text-only questions versus questions with images, with no significant difference (P = 0.302). Conclusion: Orthopaedic residents were able to answer more questions accurately than ChatGPT-3.5 and GPT-4 on orthopaedic assessment examinations. GPT-4 is superior to ChatGPT-3.5 for answering orthopaedic resident assessment examination questions. Both ChatGPT-3.5 and GPT-4 performed better on text-only questions than questions with images. It is unlikely that GPT-4 or ChatGPT-3.5 would pass the American Board of Orthopaedic Surgery written examination.


  • Open Access

    Longitudinal Assessment of Modern Spine Surgery Training

    by Alan H. Daniels, Daniel Alsoof, Christopher L. McDonald, Andrew S. Zhang, Bassel G. Diebo, Craig P. Eberson, Eren O. Kuris, William Lavelle, Christopher P. Ames, Christopher I. Shaffrey, et al.

    Background: Spine surgeons complete training through residency in orthopaedic surgery (ORTH) or neurosurgery (NSGY). A survey was conducted in 2013 to evaluate spine surgery training. Over the past decade, advances in surgical techniques and the changing dynamics in fellowship training may have affected training and program director (PD) perceptions may have shifted. Methods: This study is a cross-sectional survey distributed to all PDs of ORTH and NSGY residencies and spine fellowships in the United States. Participants were queried regarding characteristics of their program, ideal characteristics of residency training, and opinions regarding the current training environment. χ2 tests were used to compare answers over the years. Results: In total, 241 PDs completed the survey. From 2013 to 2023, NSGY increased the proportion of residents with >300 spine cases (86%-100%) while ORTH remained with >90% of residents with < 225 cases (p < 0.05). A greater number of NSGY PDs encouraged spine fellowship even for community spine surgery practice (0% in 2013 vs. 14% in 2023, p < 0.05), which continued to be significantly different from ORTH PDs (∼88% agreed, p > 0.05). 100% of NSGY PDs remained confident in their residents performing spine surgery, whereas ORTH confidence significantly decreased from 43% in 2013 to 25% in 2023 (p < 0.05). For spinal deformity, orthopaedic PDs (92%), NSGY PDs (96%), and fellowship directors (95%), all agreed that a spine fellowship should be pursued (p = 0.99). In both 2013 and 2023, approximately 44% were satisfied with the spine training model in the United States. In 2013, 24% of all PDs believed we should have a dedicated spine residency, which increased to 39% in 2023 (fellowship: 57%, ORTH: 38%, NSGY: 21%) (p < 0.05). Conclusion: Spine surgery training continues to evolve, yet ORTH and neurological surgery training remains significantly different in case volumes and educational strengths. In both 2013 and 2023, less than 50% of PDs were satisfied with the current spine surgery training model, and a growing minority believe that spine surgery should have its own residency training pathway. Level of Evidence: IV.


  • Complications of Lateral Decubitus Positioning During Orthopaedic Surgery

    by Andrew S. Zhang, Camilo Osorio, Benjamin K. Stone, James Hong, Daniel Alsoof, Christopher L. McDonald, John K. Czerwein, Alan H. Daniels

    » Lateral decubitus positioning is a nonanatomical position used for multiple orthopaedic procedures to obtain adequate surgical exposure. » Unique ophthalmologic, musculoskeletal, neurovascular, and hemodynamic complications may arise inadvertently from positioning. » Orthopaedic surgeons should be aware of the possible complications that may manifest from placing patients in the lateral decubitus position to adequately prevent and to properly manage them.


  • Severe Hypersensitivity Reaction to Dermabond Prineo After Anterior Cervical Discectomy and Fusion

    by Andrew S Zhang, Tara A. Saxena, Tunde Abubakar, Phillip Garrett Fincher, Patrick Allan Massey

    Case: A 68-year-old woman underwent an anterior cervical discectomy and fusion for cervical radiculopathy and subsequently developed a severe contact hypersensitivity reaction in response to Dermabond Prineo, beginning 10 days postoperatively. The Dermabond Prineo mesh was removed, and the patient was treated symptomatically with diphenhydramine, systemic steroids, and oral antibiotics, with complete resolution of her symptoms. Conclusion: This is the first reported contact hypersensitivity reaction to Dermabond Prineo in the context of spine surgery. Surgeons should be able to recognize this presentation and treat this appropriately.