Knee Arthritis, Meniscus Tears and Knee Pain

Most knee pain traces back to one of two problems: arthritis wearing down the joint surface, or a meniscus tear. This hub collects what Don Buford, MD has written about both: where orthobiologic injections help, where surgery is still the right answer, and where the marketing has run ahead of the evidence.

What an injection can and cannot do for knee arthritis

Osteoarthritis is the most common form of arthritis and the knee is one of the most commonly affected joints. Roughly 46 percent of people develop knee osteoarthritis at some point, and most who have it begin showing signs after age 40. The realistic goal of an orthobiologic injection is to reduce pain, stiffness and swelling and to improve function.

It is worth being blunt about what these injections do not do. No published orthopedic study shows that knee X-rays look better after a stem cell injection, and claims made at seminars that an injection grows back half an inch to an inch of cartilage are false. One level 1 study using cultured allograft adipose cells at a 100 million cell dose did report less knee pain, better function and measurable cartilage change in a few areas at one year, but that product cannot legally be used in the United States. Judge a treatment by how the knee feels and works.

PRP for knee arthritis: what the trials show

Platelet rich plasma has the deepest evidence base of any injection option for the arthritic knee. A well powered level 1 study randomized 90 patients to three monthly injections of PRP or saline; average pain scores in the PRP group fell from 8.0 to 5.7 at six months, while the saline group moved only from 7.9 to 6.6. A 2015 analysis pooling 24 studies and 2,315 patients found pain and function improved through six months and were still better than before the injection at twelve. More than 30 level 1 studies now report PRP outperforming a steroid injection and placebo, with benefit lasting at least out to a year.

Dose is the part most clinics skip. PRP that does not deliver enough platelets does not perform, which is why a 2016 level 1 trial using a preparation concentrated to roughly 1.7 times baseline platelet count is not interchangeable with high dose PRP. This office runs a hematology analyzer so the platelet dose in every injection is measured rather than assumed. Ask what your dose was and how they know it. More on preparation and dosing is collected in the PRP hub.

Bone marrow concentrate and the other cell based options

Bone marrow concentrate is aspirated from your own pelvis, concentrated in the office and injected under ultrasound guidance the same day. Patients here have reported relief years out from a single injection, and several have used it to put a recommended knee replacement on hold. Results vary from person to person and none of this is guaranteed. A Canadian pilot in 12 patients found higher doses of cultured marrow derived cells produced better outcomes while the MRIs were unchanged at one year.

Injections sold as stem cells from umbilical cord blood, amniotic fluid, Wharton's jelly or placental tissue have been shown not to contain living stem cells, and a 2024 randomized trial comparing placental derived exosomes with saline in 29 knee patients over six months found nothing. Microfat from your own adipose tissue is a different story: a 2024 randomized trial in Arthroscopy followed 75 knee osteoarthritis patients for a year, and the microfat group did better than both steroid and saline. The bone marrow hub and the FDA and safety hub cover the regulations.

A meniscus tear is a different problem

A tear on an MRI report is not by itself a reason for surgery. Degenerative tears settle down most of the time with rest, time and physical therapy, and when a degenerative tear sits in an arthritic knee, arthroscopic surgery often gives a result no better than letting the knee quiet down. An unstable tear is the opposite case. It moves too much to heal from an office injection, and the better answer is usually to repair it rather than remove it, because a meniscus you keep is a shock absorber you keep. When a repair is done, an orthobiologic is added at surgery to support healing. Many tears can be identified with ultrasound at the first visit rather than waiting on an MRI, although not every tear is visible that way; see the ultrasound hub.

Two things worth avoiding

Intra-articular steroid injections carry a real downside. A 2023 review of 113,000 patients concluded that a steroid injection within three months of a knee replacement raised infection risk by 25 percent, and newer data raises the same question around arthroscopy. Clotting the geniculate artery to treat arthritis pain has been reported in a very small pilot study with no statistical significance and about six months of partial relief, which is a thin basis for embolizing an artery. Where the evidence is genuinely mixed, as it is for PRP in patellar tendinopathy, the posts below say so.