Sánchez‐Sotelo, Joaquín

Background: Rotator cuff repair augmentation using biological materials has become popular in clinical practice to reduce the high retear rates associated with traditional repair techniques. Tissue engineering approaches, such as engineered tendon-fibrocartilage-bone composite (TFBC), have shown promise in enhancing the biological healing of rotator cuff tears in animals. However, previous studies have provided limited long-term data on TFBC repair outcomes. The effect of mechanical stimulation on TFBC has not been explored extensively. Purpose: To evaluate functional outcomes after rotator cuff repair with engineered TFBC subjected to mechanical stimulation in a 6-month follow-up using a canine in vivo model. Study Design: Controlled laboratory study. Methods: A total of 40 canines with an acute infraspinatus (ISP) tendon transection model were randomly allocated to 4 groups (n =10): (1) unilateral ISP tendon undergoing suture repair only (control surgery); (2) augmentation with engineered TFBC alone (TFBC); (3) augmentation with engineered TFBC and bone marrow-derived stem cells (BMSCs) (TFBC+C); and (4) augmentation with engineered TFBC and BMSCs, as well as mechanical stimulation (TFBC+C+M). Outcome measures—including biomechanical evaluations such as failure strength, stiffness, failure mode, gross appearance, ISP tendon and muscle morphological assessment, and histological analysis—were performed 6 months after surgery. Results: As shown in the mechanical test, the TFBC+C+M group exhibited higher failure strength compared with other repair techniques. The most common failure mode was avulsion fracture in the TFBC+C+M group, but tendon-bone junction rupture was observed predominantly in different groups. Engineered TFBC with mechanical stimulation showed over 70% relative failure strength compared with normal ISP, and the other groups showed about 50% relative failure strength. Histological analysis revealed less fat infiltration and closer-to-normal muscle fiber structure in the mechanical stimulation group. Conclusion: This study provides evidence that mechanical stimulation of engineered TFBC promotes rotator cuff regeneration, thus supporting its potential for rotator cuff repair augmentation. Clinical Relevance: This study provides valuable evidence supporting the use of a novel tissue-engineered material (TFBC) in rotator cuff repair and paves the way for advancements in the field of rotator cuff regeneration.

Introduction: International medical graduates (IMGs) continue to play an important role in the US health care system, but little is known about their trends of matching into highly competitive residencies such as orthopedic surgery. The purpose of this study was to analyze temporal trends of IMG applicants matching into US orthopedic residency programs between 2008 and 2024 and compare them with US allopathic (MD) and osteopathic (DO) graduates. Methods: Orthopedic residency specific data for years 2008 to 2024 was obtained from the National Resident Match Program and Electronic Residency Application Service. Variables collected included total number of programs, total positions offered, number of applicants (MD, DO, and IMG), positions filled, and fill rate for each group. Trends were examined using simple linear regression modeling. Results: The number of orthopedic residency programs increased from 160 (2008) to 218 (2024), with total positions increasing from 636 (2008) to 916 (2024). The IMG fill rate decreased from 2.99% in 2008 to 0.87% in 2024 ( p < 0.01 for linear trend; β −0.069). This corresponds to an absolute number decrease of 19 IMGs in 2008 to 8 in 2024. More specifically, the proportion of US IMGs decreased from 0.94% to 0.66%, and the proportion of non-US IMGs decreased from 2.04% to 0.21%. Over the 17-year study period, a total of 105 US IMGs and 110 non-US IMGs matched into orthopedic surgery. The US MD applicant fill rate decreased significantly from 96.5% to 85.0% ( p < 0.001; β −0.944). The DO applicant fill rate increased significantly from 0.31% to 13.97% ( p < 0.0001; β 0.990). Conclusion: The declining rate of IMGs matching into orthopedic residency programs in the United States underscores the growing challenges faced by IMGs in accessing training in this competitive specialty. The notable increase in DO graduates securing orthopedic residency positions likely reflects the integration of a unified accreditation system for MD and DO residency programs established in 2020. Level of Evidence: Retrospective Cohort Study; IV

Purpose To evaluate the extent to which experienced reviewers can accurately discern between artificial intelligence (AI)–generated and original research abstracts published in the field of shoulder and elbow surgery and compare this with the performance of an AI detection tool. Methods Twenty‐five shoulder‐ and elbow‐related articles published in high‐impact journals in 2023 were randomly selected. ChatGPT was prompted with only the abstract title to create an AI‐generated version of each abstract. The resulting 50 abstracts were randomly distributed to and evaluated by 8 blinded peer reviewers with at least 5 years of experience. Reviewers were tasked with distinguishing between original and AI‐generated text. A Likert scale assessed reviewer confidence for each interpretation, and the primary reason guiding assessment of generated text was collected. AI output detector (0%‐100%) and plagiarism (0%‐100%) scores were evaluated using GPTZero. Results Reviewers correctly identified 62% of AI‐generated abstracts and misclassified 38% of original abstracts as being AI generated. GPTZero reported a significantly higher probability of AI output among generated abstracts (median, 56%; interquartile range [IQR], 51%‐77%) compared with original abstracts (median, 10%; IQR, 4%‐37%; P < .01). Generated abstracts scored significantly lower on the plagiarism detector (median, 7%; IQR, 5%‐14%) relative to original abstracts (median, 82%; IQR, 72%‐92%; P < .01). Correct identification of AI‐generated abstracts was predominately attributed to the presence of unrealistic data/values. The primary reason for misidentifying original abstracts as AI was attributed to writing style. Conclusions Experienced reviewers faced difficulties in distinguishing between human and AI‐generated research content within shoulder and elbow surgery. The presence of unrealistic data facilitated correct identification of AI abstracts, whereas misidentification of original abstracts was often ascribed to writing style. Clinical Relevance With rapidly increasing AI advancements, it is paramount that ethical standards of scientific reporting are upheld. It is therefore helpful to understand the ability of reviewers to identify AI‐generated content.

Abstract Background Endoprostheses (EPC) are often utilized for reconstruction of the proximal humerus with either hemiarthroplasty (HA) or reverse arthroplasty (RA) constructs. RA constructs have improved outcomes in patients with primary lesions, but no studies have compared techniques in metastatic disease. The aim of this study is to compare functional outcomes and complications between HA and RA constructs in patients undergoing endoprosthetic reconstruction for proximal humerus metastases. Methods We retrospectively reviewed our institutional arthroplasty database to identify 66 (56% male; 38 HA and 28 RA) patients with a proximal humerus reconstruction for a non‐primary malignancy. The majority (88%) presented with pathologic fracture, and the most common diagnosis was renal cell carcinoma (48%). Resultss Patients with RA reconstructions had better postoperative forward elevation (74° vs. 32°, p < 0.01) and higher functional outcome scores. HA patients had more complications (odds ratio 13, p < 0.01), with instability being the most common complication. Conclusions Patients with nonprimary malignancies of the proximal humerus had improved functional outcomes and fewer complications after undergoing reconstruction with a reverse EPC compared to a HA EPC. Preference for reverse EPC should be given in patients with good prognosis and ability to complete postoperative rehabilitation.

AbstractAdipoRon is an adiponectin receptor 1, 2 (ADIPOR1 and ADIPOR2) agonist with potential antifibrotic effects. Whether AdipoRon can mitigate joint stiffness in a rabbit model of arthrofibrosis is unknown. We examined the efficacy of intravenous (IV) AdipoRon at mitigating contracture in a rabbit model of knee arthrofibrosis. Fifty‐six female New Zealand White rabbits were divided into three dosing groups: vehicle (dimethyl sulfoxide, DMSO), 2.5 mg/kg AdipoRon, and 5 mg/kg AdipoRon. AdipoRon, in DMSO, was administered IV preoperatively and for 5 days postoperatively (30 rabbits, Aim 1). AdipoRon was again dosed similarly after Kirschner wire (K‐wire) removal at 8 weeks (26 rabbits; Aim 2). The primary outcome of joint passive extension angle (PEA,°) was measured at 8, 10, 12, 16, and 24 weeks following index surgery. At 24 weeks, rabbits were euthanized and limbs were harvested to measure posterior capsular stiffness (N cm/°). In Aim 1, the 5 mg/kg treated rabbits had a significant increase in PEA when compared to controls at 16‐week (p < 0.05). In Aim 2, the 5 mg/kg treated rabbits had a significant increase in PEA when compared to controls at 10‐week (p < 0.05). In both aims, no significant differences were observed at later time points. Capsular stiffness was no different in any group. We are the first to report the efficacy of IV AdipoRon in a rabbit model of arthrofibrosis. We identified a significant dose‐dependent decrease in joint PEA at early time points; however, no differences were observed between groups at later time points. Clinical Significance: The present investigation provided the first assessment of AdipoRon's efficacy in mitigating knee stiffness in the current gold standard rabbit model of arthrofibrosis. Results of this investigation provided further evidence as to the potential role of AdipoRon as a preventative for arthrofibrosis in large mammals.

» The proximal humerus is a common location for primary bone tumors, and the goal of surgical care is to obtain a negative margin resection and subsequent reconstruction of the proximal humerus to allow for shoulder function. » The current evidence supports the use of reverse total shoulder arthroplasty over hemiarthroplasty when reconstructing the proximal humerus after resection of a bone sarcoma if the axillary nerve can be preserved. » There is a lack of high-quality data comparing allograft prosthetic composite (APC) with endoprosthetic reconstruction of the proximal humerus. » Reverse APC should be performed using an allograft with donor rotator cuff to allow for soft-tissue repair of the donor and host rotator cuff, leading to improvements in shoulder motion compared with an endoprosthesis.

AbstractDeep learning is a subset of artificial intelligence (AI) with enormous potential to transform orthopaedic surgery. As has already become evident with the deployment of Large Language Models (LLMs) like ChatGPT (OpenAI Inc.), deep learning can rapidly enter clinical and surgical practices. As such, it is imperative that orthopaedic surgeons acquire a deeper understanding of the technical terminology, capabilities and limitations associated with deep learning models. The focus of this series thus far has been providing surgeons with an overview of the steps needed to implement a deep learning‐based pipeline, emphasizing some of the important technical details for surgeons to understand as they encounter, evaluate or lead deep learning projects. However, this series would be remiss without providing practical examples of how deep learning models have begun to be deployed and highlighting the areas where the authors feel deep learning may have the most profound potential. While computer vision applications of deep learning were the focus of Parts I and II, due to the enormous impact that natural language processing (NLP) has had in recent months, NLP‐based deep learning models are also discussed in this final part of the series. In this review, three applications that the authors believe can be impacted the most by deep learning but with which many surgeons may not be familiar are discussed: (1) registry construction, (2) diagnostic AI and (3) data privacy. Deep learning‐based registry construction will be essential for the development of more impactful clinical applications, with diagnostic AI being one of those applications likely to augment clinical decision‐making in the near future. As the applications of deep learning continue to grow, the protection of patient information will become increasingly essential; as such, applications of deep learning to enhance data privacy are likely to become more important than ever before.Level of Evidence: Level IV.

Background: Medial-sided elbow injuries are becoming increasingly common among throwing athletes due to overuse and increased specialization at early ages. High valgus stress and repetitive elbow flexion/extension during throwing not only affects the ligaments and dynamic support of the elbow, but commonly affects the ulnar nerve. Indications: Management of cubital tunnel syndrome is initially rest, therapy, and functional training; however, if conservative measures do not appropriately address the ulnar neuropathy, surgical decompression with subcutaneous transposition is a reliable treatment option. Technique Description: An incision is created over the medial epicondyle. The medial antebrachial cutaneous nerve is identified and protected. The ulnar nerve is identified and tagged with a vessel loop to allow for appropriate handling of the nerve. Decompression of the ulnar nerve begins proximally by spreading the tissues superficial to the ulnar nerve and splitting the fascia overlying it. Then, dissection deep to the nerve is performed. A small strip of the medial intermuscular septum will be used as a sling to hold the nerve securely in the transposed position. This is released proximally and the distal attachment to the medial epicondyle is left in place. Decompression is then continued distally by releasing the superficial fascia over the flexor carpi ulnaris (FCU) and a portion of the deep FCU muscle belly and fascia. The nerve is decompressed circumferentially, while preserving penetrating branches to the FCU as able. Ultimately, the ulnar nerve is decompressed 10 cm proximal and 10 cm distal to the medial epicondyle. The intermuscular septum is then pulled over the nerve, checked for appropriate length, and sutured in place both posterior and anterior to the ulnar nerve. Results: Symptom improvement after decompression and transposition is high (>90%); however, performance outcomes in overhead and throwing athletes is variable, and return to previous or higher level of play ranges from 60% to 90%. Discussion/Conclusion: Ulnar nerve decompression and transposition can reliably address underlying symptoms, but results are mixed for return to sport outcomes in overhead and throwing athletes. Patient Consent Disclosure Statement: The author(s) attests that consent has been obtained from any patient(s) appearing in this publication. If the individual may be identifiable, the author(s) has included a statement of release or other written form of approval from the patient(s) with this submission for publication.

AbstractArthrofibrosis, which causes joint motion restrictions, is a common complication following total knee arthroplasty (TKA). Key features associated with arthrofibrosis include myofibroblast activation, knee stiffness, and excessive scar tissue formation. We previously demonstrated that adiponectin levels are suppressed within the knee tissues of patients affected by arthrofibrosis and showed that AdipoRon, an adiponectin receptor agonist, exhibited anti‐fibrotic properties in human mesenchymal stem cells. In this study, the therapeutic potential of AdipoRon was evaluated on TGFβ1‐mediated myofibroblast differentiation of primary human knee fibroblasts and in a mouse model of knee stiffness. Picrosirius red staining revealed that AdipoRon reduced TGFβ1‐induced collagen deposition in primary knee fibroblasts derived from patients undergoing primary TKA and revision TKA for arthrofibrosis. AdipoRon also reduced mRNA and protein levels of ACTA2, a key myofibroblast marker. RNA‐seq analysis corroborated the anti‐myofibrogenic effects of AdipoRon. In our knee stiffness mouse model, 6 weeks of knee immobilization, to induce a knee contracture, in conjunction with daily vehicle (DMSO) or AdipoRon (1, 5, and 25 mg/kg) via intraperitoneal injections were well tolerated based on animal behavior and weight measurements. Biomechanical testing demonstrated that passive extension angles (PEAs) of experimental knees were similar between vehicle and AdipoRon treatment groups in mice evaluated immediately following immobilization. Interestingly, relative to vehicle‐treated mice, 5 mg/kg AdipoRon therapy improved the PEA of the experimental knees in mice that underwent 4 weeks of knee remobilization following the immobilization and therapy. Together, these studies revealed that AdipoRon may be an effective therapeutic modality for arthrofibrosis.