Knee Injuries

Knee pain can come from many different structures, including ligaments, the meniscus, cartilage, tendons, bone, and the joint lining. It can also be related to osteoarthritis, inflammatory arthritis, overuse, or pain referred from the hip or back. Because similar symptoms can have different causes, a clear diagnosis matters. A knee injury after a twist or fall is different from gradual pain caused by osteoarthritis, and treatment should reflect the source of the problem.

Common Symptoms

Seek prompt medical care after major trauma, inability to bear weight, a locked knee, fever, or a hot and swollen joint.

Treatment depends on the diagnosis, injury severity, activity demands, imaging findings, and overall health. Many knee problems improve with appropriate nonsurgical care, while some injuries need orthopedic or surgical evaluation.

Standard Treatment Categories

• Physical therapy and rehabilitation: Guided exercise can improve strength, movement, balance, and knee function.
• Activity modification: Adjusting painful activity and using a gradual return-to-activity plan may support recovery.
• Medication: Anti-inflammatory medication, acetaminophen, or other pain-relieving options may be considered when appropriate.
• Weight-management support: For people with knee osteoarthritis, weight management may reduce stress on the joint and improve symptoms.
• Bracing or assistive devices: A brace, cane, or other support may be useful for selected injuries or arthritis.
• Injections or interventional care: Some people may discuss corticosteroid injections or other procedures for persistent symptoms. Recommendations for hyaluronic acid vary among professional guidelines.
• Orthopedic or surgical evaluation: Surgery may be considered for certain ligament tears, displaced meniscal injuries, fractures, a locked knee, or symptoms that have not improved with appropriate care.

Stem cell therapy for osteoarthritis and platelet-rich plasma, or PRP, are being studied because injectable biologic approaches may influence inflammation and the environment within a painful knee joint. For people with persistent symptoms, stem cell therapy for knee pain and stem cell therapy for knee injuries are areas of ongoing research.

What Researchers Are Studying

• Influence inflammatory signaling within the knee joint
• Support the joint environment and surrounding tissues
• Be delivered safely and feasibly to the affected area
• Improve pain, function, mobility, or other patient-reported outcomes

Research includes knee osteoarthritis, tendon conditions, cartilage defects, and certain sports-related knee injuries. Researchers are studying different cell sources, doses, injection methods, treatment schedules, and patient groups.

Note: Regenerative therapies for knee conditions are not FDA-approved and are investigational. Research findings do not guarantee individual results.

How Stem Cell Treatment for Knee Osteoarthritis Is Being Studied

Most published cell-based knee studies involve people with knee osteoarthritis. Researchers are evaluating different cell products, doses, treatment schedules, comparison treatments, and follow-up periods. Early clinical studies have reported improvements in pain and function after intra-articular cell injections. This work is helping researchers better understand which approaches warrant continued investigation. Stem cell treatment for knee osteoarthritis remains investigational.

2025: Single UC-MSC Injection Reported One-Year Pain and Function Improvements

Efficacy of a Single Dose of Cryopreserved Human Umbilical Cord Mesenchymal Stromal Cells for the Treatment of Knee Osteoarthritis: A Randomized, Controlled, Double-Blind Pilot Study — Read Study

This randomized, double-blind pilot study enrolled 30 people with Kellgren-Lawrence grade II or III knee osteoarthritis. Participants received a single intra-articular injection of cryopreserved umbilical-cord-derived mesenchymal stromal cells or triamcinolone, a corticosteroid. At 12 months, the cell-treatment group had better WOMAC, pain, and SF-36 scores than the triamcinolone group, and no severe adverse events were reported. These findings add to clinical research on single-dose UC-MSC treatment for knee osteoarthritis.

2023: Repeated UC-MSC Injections Reported Pain and Function Improvements

Repeated Intra-Articular Injections of Umbilical Cord-Derived Mesenchymal Stem Cells for Knee Osteoarthritis: A Phase I, Single-Arm Study — Read Study

This phase I study followed 14 people with Kellgren-Lawrence grade II or III knee osteoarthritis who received four weekly intra-articular injections of umbilical-cord-derived MSCs. At three months, participants reported improvements in pain and function scores. Five participants experienced temporary symptoms, including pain, swelling, numbness, stiffness, dizziness, or low-grade fever, all of which resolved without reported serious complications.

2019: Repeated UC-MSC Dosing Reported Greater Pain and Function Improvements

Umbilical Cord-Derived Mesenchymal Stromal Cells for Knee Osteoarthritis: Repeated MSC Dosing Is Superior to a Single MSC Dose and to Hyaluronic Acid in a Controlled Randomized Phase I/II Trial — Read Study

This randomized phase I/II trial compared repeated and single intra-articular doses of umbilical-cord-derived MSCs with hyaluronic acid in people with knee osteoarthritis. The authors reported better pain and function outcomes in the repeated-dose group than in the comparison groups during follow-up. These findings support continued research on repeated UC-MSC dosing for knee osteoarthritis.