Management of recurrent lumbar disc herniation: a comparative analysis of posterior lumbar interbody fusion and repeat discectomy.

Background: For recurrent lumbar disc herniation, many experts suggest a repeat discectomy without stabilization due to its minimal tissue manipulation, lower blood loss, shorter hospital stay, and lower cost, recent research on the role of instability in disc herniation has made fusion techniques popular among spinal surgeons. The authors compare the postoperative outcomes of posterior lumbar interbody fusion (PLIF) and repeat discectomy for same-level recurrent disc herniation. Methods: The patients included had previously undergone discectomy and presented with a same-level recurrent lumbar disc herniation. The patients were placed into two groups: 1) discectomy only, 2) PLIF based on the absence or presence of segmental instability. Preoperative and postoperative Oswestry disability index scores, duration of surgery, blood loss, duration of hospitalization, and complications were analyzed. Results: The repeat discectomy and fusion groups had 40 and 34 patients, respectively. The patients were followed up for 2.68 (1-4) years. There was no difference in the duration of hospitalization (3.73 vs. 3.29 days P=0.581) and operative time (101.25 vs. 108.82 mins, P=0.48). Repeat discectomy had lower intraoperative blood loss, 88.75 ml (50-150) versus 111.47 ml (30-250) in PLIF (P=0.289). PLIF had better ODI pain score 4.21 (0-10) versus 9.27 (0-20) (P-value of 0.018). Recurrence was 22.5% in repeat discectomy versus 0 in PLIF. Conclusion: PLIF and repeat discectomy for recurrent lumbar disc herniation have comparable intraoperative blood loss, duration of surgery, and hospital stay. PLIF is associated with lower durotomy rates and better long-term pain control than discectomy. This is due to recurrence and progression of degenerative process in discectomy patients, which are eliminated and slowed, respectively, by PLIF.

Feasibility demonstration of a device for vitreous liquid biopsy incidental to intravitreal injection.

PURPOSE: VitreoDx is an experimental device enabling push-button collection of a neat vitreous liquid biopsy incidental to an intravitreal injection. We explored the ability of the device to collect a sample usable for proteomic biomarker discovery and testing. DESIGN: Pilot study using ex vivo human eyes. METHODS: Non-vitrectomized, human eyes from nine donors 75-91 years of age were refrigerated in BSS and used within 5 days of death. Four VitreoDx devices fitted with 25G needles, and four staked needle insulin syringes with 30G needles, were inserted at equal intervals through the pars plana of each eye and held in place by a fixture. The sampling mode of each VitreoDx device was triggered to attempt to acquire a liquid biopsy up to 70 µL. The plunger of each insulin syringe was retracted to attempt to obtain a liquid biopsy with a maximum volume of 50 µL. Samples acquired with the VitreoDx were extracted to polypropylene cryovials, refrigerated to -80 ºC, and sent for offsite proteomic analysis by proximity extension assay with a focus on panels containing approved and pipelined drug targets for neovascular disease and inflammatory factors. RESULTS: Of the attempted liquid biopsies with the novel 25G VitreoDx, 92% (66 of 72) resulted in successful acquisition (>25 µL) while 89% (64 of 72) attempted by a traditional 30G needle resulted in a successful acquisition. Sample volume sufficient for proteomics array analysis was acquired by the VitreoDx for every eye. Detectable protein was found for 151 of 166 unique proteins assayed in at least 25% of eyes sampled by VitreoDx. CONCLUSIONS: The high acquisition rate achieved by the prototype was similar to that achieved in previous clinical studies where a standard syringe was used with a 25G needle to biopsy vitreous fluid directly prior to standard intravitreal injection. Successful aspiration rates were likewise high for 30G needles. Together, these suggest that it is possible to routinely acquire liquid vitreous biopsies from patients who typically receive intravitreal injections with an injection device using a standard size needle without a vitreous cutter. Protein analysis shows that proteins of interest survive the sampling mechanism and may have potential to direct care in the future.

A rare case of rebleeding brainstem cavernoma in a 5-month-old-girl.

Background: Brainstem cavernomas (BSCs) are relatively rare intracranial vascular lesions that, if left untreated, can be devastating to the patient. The lesions are associated with a myriad of symptoms, depending on their size and location. However, medullary lesions present acutely with cardiorespiratory dysfunction. We present the case of a 5-month-old child with a BSC. Case Description: A 5-month-old child presented for the 2nd time with sudden respiratory distress and excessive salivation. On the first presentation, brain magnetic resonance imaging (MRI) showed a 13 × 12 × 14 mm cavernoma at the pontomedullary junction. She was managed conservatively but presented 3 months later with tetraparesis, bulbar palsy, and severe respiratory distress. A repeat MRI showed enlargement of the cavernoma to 27 × 28 × 26 mm with hemorrhage in different stages. After hemodynamic stabilization, complete cavernoma resection was performed through the telovelar approach with neuromonitoring. Postoperatively, the child recovered motor function, but the bulbar syndrome persisted with hypersalivation. She was discharged on day 55 with a tracheostomy. Conclusion: BSCs are rare lesions that are associated with severe neurological deficits due to the compactness of important cranial nerve nuclei and other tracts in the brainstem. Early surgical excision and hematoma evacuation for superficially presenting lesions can be lifesaving. However, the risk of postoperative neurological deficits is still a major concern in these patients.

Repeat Discectomy for the Management of Same-Level Recurrent Disc Herniation: A Study of 50 Patients.

Background Same-level recurrent disc herniation remains a challenge in spine surgery. Although most surgeons agree on discectomy as the treatment of choice for primary lumbar disc herniation, the management of recurrent disc herniation remains ambiguous and largely depends on the operating surgeon. Many surgeons recommend repeat discectomy over fusion because it is cheaper and less invasive. In this study, we analyzed 50 patients who underwent a repeat discectomy. Materials and methods The patients in the study had previously been managed for lumbar disc herniation and then presented with either recurrent same-level herniation or symptoms attributed to the same level. The patients were then managed with a repeat discectomy without fusion. We analyzed the preoperative and postoperative Oswestry Disability Index (ODI), duration of surgery, blood loss, duration of hospitalization, and complications. Results Fifty patients were included: 27 females (54%), and 23 males (46%). They were followed up for an average of 2.81 years (range: 1-4). The mean duration of hospitalization was 4.06 ± 1.5 days (range: 2-8). The operative time was 104.60 minutes (range: 50-195), with an intraoperative blood loss of 85.40 mL (range: 50-150 mL). Durotomy occurred as a complication in eight (16%) patients. The recurrence rate was 26%, with 36% progressing to fusion. The change in preoperative ODI and postoperative ODI was 20.94 ± 7.24 (6-37), with a p-value of 0.04. There were no long-term complications recorded. Conclusion Repeat discectomy is a good management option for same-level recurrent disc herniation. The procedure is associated with low intraoperative blood loss and a short operating time, but there is a significant risk of durotomy. The risk of recurrence remains a concern due to the progression of degenerative changes, especially in the presence of Modic-2 changes. These advantages and disadvantages should be discussed with patients.

Dural arteriovenous fistula of the torcular herophili presenting with hydrocephalus and venous congestion in an 8-month-old child: A case report.

Dural arteriovenous fistulas (DAVFs) are direct communication between the dural arterial and venous systems. They are more common in adults. In children, they are relatively rare. Hydrocephalus is a common problem in pediatrics with a variety of causes. However, very few cases of hydrocephalus as a complication of DAVF have been reported in the literature. This case describes an 8-month-old male child with a large DAVF at the torcular herophili who presented with regression of milestones and hydrocephalus. Magnetic resonance imaging (MRI) on admission showed triventricular hydrocephalus and a massively dilated torcular with a compressed fourth ventricle. Angiography confirmed the presence of a DAVF at the torcula with arterial feeders from the posterior circulation. Endovascular embolization was performed with >80% embolization of the fistula with no complications. Control MRI immediately postoperative was acceptable. No cerebrospinal fluid (CSF) diversion was performed. At a 3-month follow-up, the child had attained all developmental milestones for age. MRI showed normal CSF dynamics and a further reduction in the size of the torcula. Despite being rare, DAVFs should be considered as a possible cause of pediatric hydrocephalus, and treating them can lead to a resolution of the mechanisms inducing hydrocephalus. CSF shunting should be reserved for those cases with persistent hydrocephalus and raised intracranial pressure despite endovascular treatment.

TFOS Lifestyle: Impact of elective medications and procedures on the ocular surface.

The word "elective" refers to medications and procedures undertaken by choice or with a lower grade of prioritization. Patients usually use elective medications or undergo elective procedures to treat pathologic conditions or for cosmetic enhancement, impacting their lifestyle positively and, thus, improving their quality of life. However, those interventions can affect the homeostasis of the tear film and ocular surface. Consequently, they generate signs and symptoms that could impair the patient's quality of life. This report describes the impact of elective topical and systemic medications and procedures on the ocular surface and the underlying mechanisms. Moreover, elective procedures performed for ocular diseases, cosmetic enhancement, and non-ophthalmic interventions, such as radiotherapy and bariatric surgery, are discussed. The report also evaluates significant anatomical and biological consequences of non-urgent interventions to the ocular surface, such as neuropathic and neurotrophic keratopathies. Besides that, it provides an overview of the prophylaxis and management of pathological conditions resulting from the studied interventions and suggests areas for future research. The report also contains a systematic review investigating the quality of life among people who have undergone small incision lenticule extraction (SMILE). Overall, SMILE refractive surgery seems to cause more vision disturbances than LASIK in the first month post-surgery, but less dry eye symptoms in long-term follow up.

Identification of small molecule inhibitors against MMP-14 via High-Throughput screening.

Matrix metalloproteinases (MMPs) are involved in various cellular events in physiology and pathophysiology through endopeptidases activity. The expression levels and activities of most MMPs remain minimal in the normal conditions, whereas some MMPs are significantly activated in pathological conditions such as cancer and neovascularization. Hence, MMPs are considered as both diagnostic markers and potential targets for therapeutic agents. Twenty-three known human MMPs share a similar active site structure with a zinc-binding motif, resulting in lack of specificity. Therefore, the enhancement of target specificity is a primary goal for the development of specific MMP inhibitors. MMP-14 regulates VEGFA/VEGFR2-system through cleavage of the non-functional VEGFR1 in vascular angiogenesis. In this study, we developed a fluorescence-based enzymatic assay using a specific MMP-14 substrate generated from VEGFR1 cleavage site. This well optimized assay was used as a primary screen method to identify MMP-14 specific inhibitors from 1,200 Prestwick FDA-approved drug library. Of ten initial hits, two compounds showed IC50 values below 30 µM, which were further validated by direct binding analysis using surface plasmon resonance (SPR). Clioquinol and chloroxine, both of which contain a quinoline structure, were identified as MMP-14 inhibitors. Five analogs were tested, four of which were found to be completely devoid of inhibitory activity. Clioquinol exhibited selectivity towards MMP-14, as it showed no inhibitory activity towards four other MMPs.

The Role of Membrane-Type 1 Matrix Metalloproteinase-Substrate Interactions in Pathogenesis.

A protease is an enzyme with a proteolytic activity that facilitates the digestion of its substrates. Membrane-type I matrix metalloproteinase (MT1-MMP), a member of the broader matrix metalloproteinases (MMP) family, is involved in the regulation of diverse cellular activities. MT1-MMP is a very well-known enzyme as an activator of pro-MMP-2 and two collagenases, MMP-8 and MMP-13, all of which are essential for cell migration. As an anchored membrane enzyme, MT1-MMP has the ability to interact with a diverse group of molecules, including proteins that are not part of the extracellular matrix (ECM). Therefore, MT1-MMP can regulate various cellular activities not only by changing the extra-cellular environment but also by regulating cell signaling. The presence of both intracellular and extra-cellular portions of MT1-MMP can allow it to interact with proteins on both sides of the cell membrane. Here, we reviewed the MT1-MMP substrates involved in disease pathogenesis.

Lymphangiogenesis Guidance Mechanisms and Therapeutic Implications in Pathological States of the Cornea.

Corneal lymphangiogenesis is one component of the neovascularization observed in several inflammatory pathologies of the cornea including dry eye disease and corneal graft rejection. Following injury, corneal (lymph)angiogenic privilege is impaired, allowing ingrowth of blood and lymphatic vessels into the previously avascular cornea. While the mechanisms underlying pathological corneal hemangiogenesis have been well described, knowledge of the lymphangiogenesis guidance mechanisms in the cornea is relatively scarce. Various signaling pathways are involved in lymphangiogenesis guidance in general, each influencing one or multiple stages of lymphatic vessel development. Most endogenous factors that guide corneal lymphatic vessel growth or regression act via the vascular endothelial growth factor C signaling pathway, a central regulator of lymphangiogenesis. Several exogenous factors have recently been repurposed and shown to regulate corneal lymphangiogenesis, uncovering unique signaling pathways not previously known to influence lymphatic vessel guidance. A strong understanding of the relevant lymphangiogenesis guidance mechanisms can facilitate the development of targeted anti-lymphangiogenic therapeutics for corneal pathologies. In this review, we examine the current knowledge of lymphatic guidance cues, their regulation of inflammatory states in the cornea, and recently discovered anti-lymphangiogenic therapeutic modalities.

Therapeutic Strategies for Restoring Perturbed Corneal Epithelial Homeostasis in Limbal Stem Cell Deficiency: Current Trends and Future Directions.

Limbal stem cells constitute an important cell population required for regeneration of the corneal epithelium. If insults to limbal stem cells or their niche are sufficiently severe, a disease known as limbal stem cell deficiency occurs. In the absence of functioning limbal stem cells, vision-compromising conjunctivalization of the corneal epithelium occurs, leading to opacification, inflammation, neovascularization, and chronic scarring. Limbal stem cell transplantation is the standard treatment for unilateral cases of limbal stem cell deficiency, but bilateral cases require allogeneic transplantation. Herein we review the current therapeutic utilization of limbal stem cells. We also describe several limbal stem cell markers that impact their phenotype and function and discuss the possibility of modulating limbal stem cells and other sources of stem cells to facilitate the development of novel therapeutic interventions. We finally consider several hurdles for widespread adoption of these proposed methodologies and discuss how they can be overcome to realize vision-restoring interventions.

Lymphatic Vessel Regression and Its Therapeutic Applications: Learning From Principles of Blood Vessel Regression.

Aberrant lymphatic system function has been increasingly implicated in pathologies such as lymphedema, organ transplant rejection, cardiovascular disease, obesity, and neurodegenerative diseases including Alzheimer's disease and Parkinson's disease. While some pathologies are exacerbated by lymphatic vessel regression and dysfunction, induced lymphatic regression could be therapeutically beneficial in others. Despite its importance, our understanding of lymphatic vessel regression is far behind that of blood vessel regression. Herein, we review the current understanding of blood vessel regression to identify several hallmarks of this phenomenon that can be extended to further our understanding of lymphatic vessel regression. We also summarize current research on lymphatic vessel regression and an array of research tools and models that can be utilized to advance this field. Additionally, we discuss the roles of lymphatic vessel regression and dysfunction in select pathologies, highlighting how an improved understanding of lymphatic vessel regression may yield therapeutic insights for these disease states.

Comparison of Low Degree/High Degree and Zernike Expansions for Evaluating Simulation Outcomes After Customized Aspheric Laser Corrections.

Purpose: The purpose of this study was to compare the low degree/high degree (LD/HD) and Zernike Expansion simulation outcomes evaluating the corneal wavefront changes after theoretical conventional and customized aspheric photorefractive ablations. Methods: Initial anterior corneal surface profiles were modeled as conic sections with pre-operative apical curvature, R0, and asphericity, Q0. Postoperative apical curvature, R1, was computed from intended defocus correction, D, diameter zone, S, and target postoperative asphericity, Q1. Coefficients of both Zernike and LD/HD polynomial expansions of the rotationally symmetrical corneal profile were computed using scalar products. We modeled different values of D, R0, Q0, S, and ΔQ = Q1 to Q0. The corresponding postoperative changes in defocus (Δz20 vs. Δg20), fourth order (Δz40 vs. Δg40) and sixth order (Δz60 vs. Δg60) Zernike and LD/HD spherical aberrations (SAs) were compared. In addition, retrospective clinical data and wavefront measurements were obtained from two examples of two patient eyes before and after corneal laser photoablation. Results: The z20, varied with both R0 and Q0, whereas the LD/HD defocus coefficient, g20, was relatively robust to changes in asphericity. Variations of apical curvature better correlated with defocus and ΔQ with SA coefficients in the LD/HD classification. The impact of ΔQ was null on g20 but induced significant linear variations in z20 and fourth order SA coefficients. LD/HD coefficients provided a good correlation with the visual performances of the operated eyes. Conclusions: Simulated variations in postoperative corneal profile and wavefront expansion using the LD/HD approach showed good correlations between defocus and asphericity variations with variations in corneal curvature and SA coefficients, respectively. Translational Relevance: The relevance of this study was to provide a clinically relevant alternative to Zernike polynomials for the interpretation of wavefront changes after customized aspheric corrections.

Corneal lymphangiogenesis as a potential target in dry eye disease - a systematic review.

Dry eye disease (DED) is a common ocular surface condition causing symptoms of significant discomfort, visual disturbance, and pain. With recent advancements, DED has become recognized as a chronic self-perpetuating inflammatory condition triggered by various internal and environmental factors. DED has been shown to arise from the activation of both the innate and adaptive immune systems, leading to corneal epithelium and lacrimal gland dysfunction. While the cornea is normally avascular and thus imbued with angiogenic and lymphangiogenic privilege, various DED models have revealed activated corneal antigen-presenting cells in regional lymph nodes, suggesting the formation of new corneal lymphatic vessels in DED. The recent availability of reliable lymphatic cell surface markers such as LYVE-1 has made it possible to study lymphangiogenesis. Accordingly, numerous studies have been published within the last decade discussing the role of lymphangiogenesis in DED pathology. We systematically review the literature to identify and evaluate studies presenting data on corneal lymphangiogenesis in DED. There is considerable evidence supporting corneal lymphangiogenesis as a central mediator of DED pathogenesis. These findings suggest that anti-lymphangiogenic therapeutic strategies may be a viable option for the treatment of DED, a conclusion supported by the limited number of reported clinical trials examining anti-lymphangiogenic modalities in DED.

Artificial intelligence in ophthalmology during COVID-19 and in the post COVID-19 era.

PURPOSE OF REVIEW: To highlight artificial intelligence applications in ophthalmology during the COVID-19 pandemic that can be used to: describe ocular findings and changes correlated with COVID-19; extract information from scholarly articles on SARS-CoV-2 and COVID-19 specific to ophthalmology; and implement efficient patient triage and telemedicine care. RECENT FINDINGS: Ophthalmology has been leading in artificial intelligence and technology applications. With medical imaging analysis, pixel-annotated distinguishable features on COVID-19 patients may help with noninvasive diagnosis and severity outcome predictions. Using natural language processing (NLP) and data integration methods, topic modeling on more than 200 ophthalmology-related articles on COVID-19 can summarize ocular manifestations, viral transmission, treatment strategies, and patient care and practice management. Artificial intelligence for telemedicine applications can address the high demand, prioritize and triage patients, as well as improve at home-monitoring devices and secure data transfers. SUMMARY: COVID-19 is significantly impacting the way we are delivering healthcare. Given the already successful implementation of artificial intelligence applications and telemedicine in ophthalmology, we expect that these systems will be embraced more as tools for research, education, and patient care.

Simultaneous fluorescence imaging of distinct nerve and blood vessel patterns in dual Thy1-YFP and Flt1-DsRed transgenic mice.

Blood vessels and nerve tissues are critical to the development and functionality of many vital organs. However, little is currently known about their interdependency during development and after injury. In this study, dual fluorescence transgenic reporter mice were utilized to observe blood vessels and nervous tissues in organs postnatally. Thy1-YFP and Flt1-DsRed (TYFD) mice were interbred to achieve dual fluorescence in the offspring, with Thy1-YFP yellow fluorescence expressed primarily in nerves, and Flt1-DsRed fluorescence expressed selectively in blood vessels. Using this dual fluorescent mouse strain, we were able to visualize the networks of nervous and vascular tissue simultaneously in various organ systems both in the physiological state and after injury. Using ex vivo high-resolution imaging in this dual fluorescent strain, we characterized the organizational patterns of both nervous and vascular systems in a diverse set of organs and tissues. In the cornea, we also observed the dynamic patterns of nerve and blood vessel networks following epithelial debridement injury. These findings highlight the versatility of this dual fluorescent strain for characterizing the relationship between nerve and blood vessel growth and organization.

Needle arthroscopy of the radiocarpal and middle carpal joints in standing sedated horses.

OBJECTIVE: To develop a technique for standing diagnostic needle arthroscopy of the radiocarpal and middle carpal joints in standing sedated horses. STUDY DESIGN: Experimental study. ANIMALS: Six cadaveric forelimbs (phase 1) and six healthy horses (phase 2). METHODS: In phase 1, six cadaveric forelimbs were used to assess needle arthroscopic evaluation of both joints. Six healthy horses were subsequently enrolled in phase 2 to validate the procedure in live animals. The joint was maintained in flexion with a custom-made splint and base. RESULTS: In phase 1, needle arthroscopy allowed thorough evaluation of the dorsal and palmar recesses of both joints with traditional arthroscopic portals. In phase 2, joint evaluation was also thorough but only dorsal approaches were performed. All horses underwent radiocarpal joint arthroscopy, whereas the middle carpal joint was evaluated in only three of six horses because of limb movement. The technique was quickly performed and well tolerated by all horses. Complications included moderate movement, mild iatrogenic cartilage damage, and mild hemarthrosis. CONCLUSION: Standing needle arthroscopy allowed thorough evaluation of the dorsal aspect of both joints, although only three of six middle carpal joints were assessed because of movement limitations. CLINICAL SIGNIFICANCE: The proposed technique offers an alternative diagnostic tool for radiographically silent intra-articular lesions of the carpus while initially avoiding the cost and risks associated with general anesthesia. Arthroscopy of a single joint is recommended to minimize risks associated with movement during the procedure.

Proteomics-Based Characterization of the Effects of MMP14 on the Protein Content of Exosomes from Corneal Fibroblasts.

BACKGROUND: Exosomes secreted by corneal fibroblasts contain matrix metalloproteinase (MMP) 14, which is known to influence pro-MMP2 accumulation on exosomes. Accordingly, we hypothesized that the enzymatic activity of MMP14 may alter the protein content of corneal fibroblast- secreted exosomes. OBJECTIVE: The aim of this study was to investigate the effects of MMP14 on the composition and biological activity of corneal fibroblast-derived exosomes. METHODS: Knock out of the catalytic domain (ΔExon4) of MMP14 in corneal fibroblasts was used to determine the effect of MMP14 expression on the characteristics of fibroblast-secreted exosomes. The amount of secreted proteins and their size distribution were measured using Nano Tracking Analysis. Proteins within exosomes from wild-type (WT) and ΔExon4-deficient fibroblasts were identified by liquid chromatography-tandem mass spectrometry (MS/MS) proteomics analysis. The proteolytic effects of MMP14 were evaluated in vitro via MS identification of eliminated proteins. The biological functions of MMP14-carrying exosomes were investigated via fusion to endothelial cells and flow cytometric assays. RESULTS: Exosomes isolated from WT and ΔExon4-deficient fibroblasts exhibited similar size distributions and morphologies, although WT fibroblasts secreted a greater amount of exosomes. The protein content, however, was higher in ΔExon4-deficient fibroblast-derived exosomes than in WT fibroblast-derived exosomes. Proteomics analysis revealed that WT-derived exosomes included proteins that regulated cell migration, and ΔExon4 fibroblast-derived exosomes contained additional proteins that were cleaved by MMP14. CONCLUSION: Our findings suggest that MMP14 expression influences the protein composition of exosomes secreted by corneal fibroblasts, and through those biological components, MMP14 in corneal fibroblasts derived-exosomes may regulate corneal angiogenesis.

Transgenic models for investigating the nervous system: Currently available neurofluorescent reporters and potential neuronal markers.

Recombinant DNA technologies have enabled the development of transgenic animal models for use in studying a myriad of diseases and biological states. By placing fluorescent reporters under the direct regulation of the promoter region of specific marker proteins, these models can localize and characterize very specific cell types. One important application of transgenic species is the study of the cytoarchitecture of the nervous system. Neurofluorescent reporters can be used to study the structural patterns of nerves in the central or peripheral nervous system in vivo, as well as phenomena involving embryologic or adult neurogenesis, injury, degeneration, and recovery. Furthermore, crucial molecular factors can also be screened via the transgenic approach, which may eventually play a major role in the development of therapeutic strategies against diseases like Alzheimer's or Parkinson's. This review describes currently available reporters and their uses in the literature as well as potential neural markers that can be leveraged to create additional, robust transgenic models for future studies.

Diagnostic needle arthroscopy of the tarsocrural joint in standing sedated horses.

OBJECTIVE: To develop and assess a needle arthroscopic technique to diagnose conditions of the tarsocrural joint (TCj) in standing sedated horses. STUDY DESIGN: Experimental study. SAMPLE POPULATION: Six cadaveric hind limbs (phase 1) and six healthy horses (Phase 2). METHODS: In phase 1, each TCj was examined with a 1.2-mm-needle arthroscope. Suitability of the needle arthroscope and degree of joint visualization with traditional arthroscopic approaches were assessed. In phase 2, the feasibility of the procedure was assessed in six standing healthy horses. A custom-made splint and base were developed to maintain joint flexion during the procedure. RESULTS: Thorough evaluation of the dorsal intra-articular structures of the TCj via dorsomedial and dorsolateral approaches was possible in both phases. The procedure was feasible, quickly performed, and well tolerated by all horses. Complications consisted of moderate movement (2/6 horses) and hemarthrosis (3/6 horses). CONCLUSION: Diagnostic standing needle arthroscopy of the TCj allowed thorough evaluation of the dorsal aspect of the joint while avoiding the cost and risks associated with general anesthesia. Inadvertent puncture of the dorsomedial vasculature with the cannula and obturator led to significant hemarthrosis. CLINICAL IMPACT: Needle arthroscopy of the TCj offers an alternative diagnostic tool when traditional imaging techniques (radiography and ultrasonography) are unrewarding or nondiagnostic. The technique is conceived mainly for diagnostic purposes, but its use during short interventions warrants investigation.