Knee OA is a chronic disease that affects all races, genders, and ages, but it is most prevalent in obese and elderly people. Worldwide, arthritis is considered to be the fourth leading cause of disability.1 In developing and developed countries, knee OA may cause a significant decline in the quality of life for individuals >65 years due to joint pain and disability.1 Nonoperative treatment can be successful in patients with mild to moderate arthritis with pain.
Current treatment options for knee OA, including physical therapy and anti-inflammatory drugs, aim to remedy the symptoms, but they do little to treat the underlying causes of knee OA pain. When a patient presents with advanced arthritis of the knee as confirmed by radiographic findings (classified as Kellgren–Lawrence grade of 3 or 4), the standard approach has been a total knee arthroplasty (TKA) after the patient has failed conservative treatment. The annual rate of total knee replacement in the United States has doubled since 2000, especially in those 45 – 65 years.2 The total number of procedures performed each year now exceeds 640,000, at a total annual cost of about $10.2 billion.2 Multiple studies show that TKA has favorable outcomes in pain relief and functional improvement in patients >60 years when evaluated at a follow-up of 10 years after surgery.2
However, some patients are hesitant to proceed with surgery due to fear of surgical pain and procedural complications. The known complications include deep vein thrombosis, pulmonary embolism, nerve injury, and infection. In addition, up to 20% of patients continue to complain of pain following a total knee replacement.3 Finally, in the young population (<50 years), there are concerns related to the potential need of revision knee surgery in the future.3
Alternative treatments for knee OA have recently emerged, including the use of platelet-rich plasma (PRP). A recent meta-analysis that included 10 randomized controlled trials with a total of 1069 patients demonstrated that, compared with hyaluronic acid and saline, intra-articular PRP injection may have more benefits in pain relief and functional improvement in patients with symptomatic knee OA at 1-year post-injection.4 Another smaller study examined patients who had experienced mild knee OA (Kellgren–Lawrence grade <3) for an average of 14 months. Each patient underwent magnetic resonance imaging for the evaluation of joint damage and then received a single PRP injection. The patients were assessed at regular intervals, with improvement in pain lasting up to 12 months.5
Additional orthobiologic options include the use of bone marrow and adipose-derived stem cell (ASC) injections for a variety of knee conditions, including knee OA. Mesenchymal stem cells (MSCs) are multipotent cells that have been used for the treatment of OA in clinical trials because of their regeneration potential and anti-inflammatory effects.6 Bone marrow stem cells (BMSCs) were first used to repair cartilage damage in humans in 1998. However, BMSCs had particular challenges, including low stem cell yield, pain, and possible morbidities during bone marrow aspiration. An alternative is ASCs, which may be more suitable clinically because of the high stem cell yield from lipoaspirates, faster cell proliferation, and less discomfort and morbidities during the harvesting procedure.7 In addition, these adult stem cells can contribute to the chondrogenic, osteogenic, adipogenic, myogenic, and neurogenic lineages.8 One study demonstrated that the contents of cartilage glycosaminoglycans significantly increased in specific areas of a knee joint treated with ASCs.9,10 This increased glycosaminoglycan content in hyaline cartilage may explain the observed visual analog score (VAS) improvement and clinical results. Other studies suggest that the chondrogenic action of ASCs may depend more on regenerative signaling by activated perivascular cells and signaling of trophic and paracrine mediators, such as vascular endothelial growth factor.9,10 Finally, the mechanism of action may include providing volume, support, cushioning, and filling of soft tissue defects.11
The Lipogems method and device, approved by the U.S. Food and Drug Administration, is used to harvest ASCs, cleanse, and micro-fracture adipose tissue while maintaining the perivascular niche that contains pericytes. The purpose of this study was to evaluate the safety and efficacy of using autologous, micro-fractured, minimally manipulated adipose tissue in patients with severe refractory knee OA.
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