Cartilage—a type of connective tissue that lines the end of bones—provides cushioning for joints and prevents bones from rubbing together. Severe knee cartilage loss makes walking, sitting, standing, squatting, and going up and down stairs extremely painful. Cartilage implantation, also called autologous chondrocyte implantation (ACI), is a newer procedure used to grow cartilage cells.
This zone confers the tensile properties to the AC, and helps resist the sheer forces experienced by the joint. The middle layer or the transitional zone which makes up 40–60% of the AC thickness is characterized by obliquely organized thicker collagen fibrils, and slightly larger chondrocytes at a relatively lower density. The transitional zone is the first line of resistance to the compressive forces imposed by the articulation. In the deep zone, the collagen fibrils are the thickest and are arranged perpendicular to the articulating surfaces. The very large chondrocytes are typically arranged in columns, parallel to the collagen fibrils.
When it comes to dealing with cartilage defects of the knees, finding the right treatment is crucial. These defects can cause significant pain and discomfort, making it difficult to perform everyday activities. Fortunately, there are several treatments available that can help alleviate symptoms and improve the overall health of the knee joint.
Gene therapy is another method being investigated to enhance cartilage regeneration. No serious adverse events occurred and although there was a dose-dependent trend suggesting clinical improvements, the differences observed were not statistically significant.74 Further research is required before conclusions can be drawn regarding the clinical efficacy of gene therapy. Cycling is another exercise modality that reduces weight-bearing stress on joints.
Surgical Options
1. Microfracture: This procedure involves creating small holes in the bone beneath the damaged cartilage to stimulate the growth of new cartilage.
It serves as a lubricant that allows bones to move smoothly within a joint and provides shock absorption to decrease pressure and friction within joints. Corticosteroid injections may not be recommended for patients who have diabetes or other problems with blood sugar since corticosteroid use can raise blood sugar levels. A physical therapist will evaluate your knee and hip alignment, muscle strength, range of motion, and movement patterns to develop an individualized plan of care to address your limitations.
2. Autologous Chondrocyte Implantation (ACI): In this procedure, healthy cartilage cells are harvested from the patient’s own body, grown in a lab, and then implanted into the damaged area of the knee.
MSCs offer a promising cell source for regeneration and repair of cartilage lesions, as they have the ability to differentiate into chondrocytes, and are easy to harvest, with minimal donor site morbidity (Park et al., 2018). MSCs used for repairing the cartilage lesions are obtained from a variety of autologous tissues including bone marrow (BM-MSCs), adipose tissue (AT-MSCs) and peripheral blood (PB-MSCs) (Reissis et al., 2016). Depending on the specific cartilage pathology, the MSCs can either be implanted into the defect following surgical incision, or administered via intra-articular injection. A post-surgical prognosis study assessing the efficacy of AT-MSCs implantation for cartilage lesions observed 76% of the patients had the repair rated as abnormal or severely abnormal as per the International Cartilage Repair Society standards (Koh et al., 2014). Furthermore, compared to MSCs implantation, intra-articular injections have a higher risk of the cells migrating to non-target tissues (Reissis et al., 2016).
3. Osteochondral Autograft Transplantation (OAT): This involves transferring healthy cartilage and bone from one part of the knee to the damaged area.
Non-Surgical Options
With knee cartilage injuries, pain and locking of the knee can lead to difficulty with walking, running, and other activities. Pain is the most obvious knee cartilage damage symptom, but an equally frequent warning sign is recurring knee swelling. Knee pain can come from a variety of sources so it can be difficult to pinpoint cartilage damage as the reason. An arthrotomy is performed to expose the defect,which is then prepared in the standard fashion. The defect is templated, and acommercially available patch (either synthetic, porcine I/III collagen, orhyaluronan based) is cut according to the defect. A thin layer of fibrin glue isplaced into the defect after hemostasis has been achieved and the cartilagepaste is applied evenly across the defect.
Several studies have highlighted the role of hypoxia in chondrogenic differentiation of mesenchymal stem cells (MSCs) (Robins et al., 2005; Elabd et al., 2018; Contentin et al., 2020). Proliferation of bone marrow MSCs was enhanced under hypoxia, together with increased chondrogenic ability, and higher type II collagen and aggrecan mRNA expressions (Bornes et al., 2015). Furthermore, hypoxia mediated HIF-1α stabilization led to activation of SOX9 and subsequent differentiation of MSCs to chondrocytes (Robins et al., 2005). Thus, targeting the hypoxic pathways, possibly by inhibiting prolyl hydroxylases (Joharapurkar et al., 2018), could be therapeutic strategy for cartilage repair.
1. Physical Therapy: A targeted exercise program can help strengthen the muscles around the knee and improve range of motion.
2. Hyaluronic Acid Injections: These injections can help lubricate the knee joint and reduce pain and inflammation.
3. Platelet-Rich Plasma (PRP) Therapy: This treatment involves injecting a concentration of the patient’s own platelets into the knee to promote healing.
Frequently Asked Questions
- What is the recovery time for surgical treatments?
- Can non-surgical treatments be effective for all types of cartilage defects?
- Are there any risks associated with these treatments?
Overall, when considering treatments for cartilage defects of the knees, it’s important to consult with a healthcare professional to determine the best course of action based on the specific needs and condition of the individual. By exploring both surgical and non-surgical options, patients can find relief from pain and improve their quality of life.
