Azua, Eric N.

Background: The microvasculature of the human meniscus has been previously described by Arnoczky and Warren. However, to date, the qualitative and quantitative extra-articular vascular anatomy of the medial meniscus has not been characterized. Purposes: To perform a qualitative and quantitative anatomic study of the extra-articular medial meniscal vasculature and to introduce the novel “medial meniscal artery” (MMA), potentially providing future guidelines for the treatment of meniscal abnormalities. Study Design: Descriptive laboratory study. Methods: A total of 33 unpaired, frozen human cadaveric knees were dissected. The femoral artery was identified and cannulated using an angiocatheter. The arteries were perfused with a red acrylic paint solution, allowing for improved visualization. Artery dimensions and distances were measured using a digital caliper. Perfused specimens were imaged using computed tomography and segmented using 3D reconstruction software to identify vessels and repeat artery measurements digitally. Results: The MMA was consistently identified in all specimens. In 27 (82%) of 33 specimens, the MMA branched directly from the popliteal artery; in 5 (15%), the MMA shared a common trunk with the inferior medial genicular artery; and in 1 specimen (3%), the MMA shared a common branch with the inferior lateral genicular artery. The MMA was easily distinguishable from the superior, inferior, and middle genicular arteries, given its direct course to the medial joint line with terminal branches to the posterior horn of the medial meniscus and deep to the semimembranosus tendon. The MMA exhibited a consistently smaller vessel diameter relative to the genicular arteries. Conclusion: This is the first study to identify and quantitatively describe the MMA in the human knee. The MMA can be identified consistently on gross anatomic dissection in cadaveric donors of varying demographics. Further research is needed to identify and characterize the artery in vivo and to determine the MMA’s role in meniscus preservation surgery. Clinical Relevance: The findings of this study will provide future avenues of research toward understanding medial meniscus vascularization and the genesis of potential degenerative changes when vascularization is poor. This will help to further refine diagnostic and treatment options for meniscus revascularization and compartment preservation. Additionally, this study may help define safe zones in the knee during posterior approaches and expand the base of knowledge for emerging vascular procedures such as genicular artery embolization.

Objectives: The microvasculature of the human meniscus has been previously described by Arnoczky and Warren. However, to date the qualitative and quantitative extra-articular vascular anatomy of the medial meniscus has not yet been characterized. Therefore, the purpose of our study was to perform a qualitative and quantitative anatomic study of the extra-articular medial meniscal vasculature and to introduce the novel “medial meniscal artery” (MMA), potentially providing future guidelines for the treatment of meniscal pathology. Methods: Thirty-three unpaired frozen human cadaveric knees were dissected. The popliteal artery was identified and cannulated with an angiocatheter. The arteries were perfused with a red acrylic paint solution allowing for improved visualization. Artery dimensions and distances were measured using a digital caliper. Perfused specimens were imaged with Computed Tomography scanning and segmented using software to identify vessels and repeat artery measurements. Results: The MMA was consistently identified in all specimens. In 26 of 33 (82%) specimens, the MMA branched directly from the popliteal artery, while in 6, the MMA shared a common trunk with the inferior medial genicular artery (IMGA). The MMA was easily distinguishable from the superior MGA, inferior MGA, and MGA, given its direct course to the medial joint line with terminal branches to the posterior horn of the medial meniscus and deep to the semimembranosus tendon. The MMA exhibited a consistently smaller vessel diameter relative to the genicular arteries. Conclusions: This is the first study identifying and quantitively describing the MMA in the human knee. The MMA can be identified consistently on gross anatomic dissection in patients of varying demographics. The findings of this study will provide future avenues of study toward understanding the medial meniscus vascularization and the genesis of potential degenerative changes when vascularization is poor. This will help to further refine diagnostic and treatment options for meniscus revascularization and compartment preservation. Additionally, this study may help define safe zones in the knee during posterior approaches, as well as furthering the base of knowledge for emerging vascular procedures such as genicular artery embolization. Further research is needed to identify and characterize the artery in vivo and to determine the MMA’s role in meniscus preservation.

Objectives: The vascularity of the human meniscus was first famously described by Arnoczky and Warren, who used histological analysis to map out vessel contributions to the medial and lateral menisci. This study determined that the medial and lateral superior and inferior genicular arteries branches give rise to a perimeniscal capillary plexus within the capsular and synovial tissues of the knee. However, since this study, there have been limited investigations into the macro- and microvascularity of the menisci. This includes anatomical, biomechanical, and imaging studies. Doppler ultrasound is an easily accessible, safe, and non-invasive modality that gives clinicians real-time visualization of vascular anatomy. To date, there have been no ultrasound studies that have highlighted vascular deviations from the popliteal artery to the medical meniscus, including the newly discovered medial meniscal artery (MMA), as described in Part 1 of this study (Figure 1, from Part 1 of this investigation). The purpose of this study was to use find a reproducible ultrasound technique to identify the MMA and provide a detailed characterization of the vessel’s precise anatomy. We hypothesized that the MMA would be consistently identifiable in vivo using ultrasound imaging and that multiple anatomic variants of the MMA would exist. Methods: Fifty-six patients underwent ultrasound examination of the left knee. Patient demographics were collected. The MMA was isolated by one of two techniques. In the first approach, the inferior medial genicular artery (IMGA) was isolated and followed back to the popliteal artery, where the examiner then coursed the artery proximally to find medial-sided vasculature branching to the medial meniscus. In the second approach, the probe was started on the medial meniscus and once an arterial supply was found, it was traced back to the popliteal artery. Once the MMA was isolated by either technique, the following variables were measured: presence or absence of MMA, artery diameter, presence of arterial calcifications or atheromatous plaques, and any vascular variations. Once the MMA was found and isolated in the left knee, its presence was investigated in the right knee. Results: The MMA was identified in 50/56 patients (89.2%). The average vessel diameter was 0.89 mm (SD ± 0.39). All 50 patients with a MMA present on the left knee also had the presence of the artery on the right knee. None of the MMA isolated in this study were noted to have any plaques or calcifications. 45 patients were noted to have a Type 1 MMA, whereas five patients were noted to have a Type 2 MMA where the vessel shares an origin with the IMGA (Figure 2). Conclusions: This is the first study to utilize ultrasound to isolate and characterize the MMA in a in vivo human model. The MMA can be consistently seen on ultrasonography in the majority of patients and ultrasound examination demonstrated that the artery perforates into the meniscal tissue to contribute to the meniscal microplexus. The key methods to ensure reproducible identification of the artery and patient characteristics that produce lesser quality images are discussed in detail. Ultrasound identification in clinic may serve as a point-of-care diagnostic modality to determine the likelihood of success of procedures such as medial meniscal repair, given the artery provides a direct blood supply to the meniscus. The MMA may play a pivotal role in meniscal injury, repair, healing, and preservation. Future studies are necessary to determine the extent to which this vessel contributes to said mechanisms.

Context: Many clinicians, trainers, and athletes do not have a true understanding of the effects of commonly used performance-enhancing drugs (PEDs) on performance and health. Objective: To provide an evidence-based review of 7 commonly used pharmacological interventions for performance enhancement in athletes. Data Sources: PubMed and Scopus databases were searched on April 8, 2022. Study Selection: Systematic reviews (SRs) and meta-analyses (MAs) assessing the performance-enhancing effects of the following interventions were included: androgenic anabolic steroids (AAS), growth hormone (GH), selective androgen receptor modulators (SARMs), creatine, angiotensin-converting enzyme (ACE)-inhibitors, recombinant human erythropoietin (rHuEPO), and cannabis. Study Design: Umbrella review of SRs and MAs. Level of Evidence: Level 4. Data Extraction: Primary outcomes collected were (1) body mass, (2) muscle strength, (3) performance, and (4) recovery. Adverse effects were also noted. Results: A total of 27 papers evaluating 5 pharmacological interventions met inclusion criteria. No studies evaluating SARMs or ACE-inhibitors were included. AAS lead to a 5% to 52% increase in strength and a 0.62 standard mean difference in lean body mass with subsequent lipid derangements. GH alters body composition, without providing a strength or performance benefit, but potential risks include soft tissue edema, fatigue, arthralgias, and carpel tunnel syndrome. Creatine use during resistance training can safely increase total and lean body mass, strength, and performance in high-intensity, short-duration, repetitive tasks. Limited evidence supports rHuEPO benefit on performance despite increases in both VO 2 max and maximal power output, and severe cardiovascular risks are documented. Cannabis provides no performance benefit and may even impair athletic performance. Conclusion: In young healthy persons and athletes, creatine can safely provide a performance-enhancing benefit when taken in controlled doses. AAS, GH, and rHuEPO are associated with severe adverse events and do not support a performance benefit, despite showing the ability to change bodily composition, strength, and/or physiologic measures. Cannabis may have an ergolytic, instead of ergogenic, effect.