Śmigıelski, Robert

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.

AbstractSubchondral insufficiency fractures of the knee (SIFK) can result in high rates of osteoarthritis and arthroplasty. The implantable shock absorber (ISA) implant is a titanium and polycarbonate urethane device which reduces the load on the medial compartment of the knee by acting as an extra-articular load absorber while preserving the joint itself. The purpose of this study was to evaluate whether partially unloading the knee with the ISA altered the likelihood of progression to arthroplasty utilizing a validated predictive risk model (SIFK score). A retrospective case-control (2:1) study was performed on patients with SIFK without any previous surgery and on those implanted with the ISA with the primary outcome being progression to arthroplasty compared with nonoperative treatment at 2 years. Baseline and final radiographs, as well as magnetic resonance imagings, were reviewed for the evaluation of meniscus or ligament injuries, insufficiency fractures, and subchondral edema. Patients from a prospective study were matched using the exact SIFK Score, a validated predictive score for progression to arthroplasty in patients with SIFK, to those who received the ISA implant. Kaplan–Meier analysis was conducted to assess survival. A total of 57 patients (38 controls:19 ISA) with a mean age of 60.6 years and 54% female were included. The SIFK score was matched exactly between cases and controls for all patients. The 2-year survival rate of 100% for the ISA group was significantly higher than the corresponding rate of 61% for the control group (p < 0.01). In ISA, 0% of the patients converted to arthroplasty at 2 years, and 5% (one patient) had hardware removal at 1 year. When stratified by risk, the ISA group did not have a significantly higher survival compared with low-risk (p = 0.3) or medium-risk (p = 0.2) controls, though it had a significantly higher survival for high-risk groups at 2 years (100 vs. 15%, p < 0.01). SIFK of the medial knee can lead to significant functional limitation and high rates of conversion to arthroplasty. Implants such as the ISA have the potential to alter the progression to arthroplasty in these patients, especially those at high risk.