Meniscus injuries of the knee are common. There are lots of treatment options including meniscus tear surgery or injections. But which one is the best to address your meniscus tear pain? The data surprises almost everyone.
Anatomy of the Meniscus
Let’s start by looking at the anatomy of the meniscus. Each knee has two menisci, one on the medial aspect of the knee and one on the lateral aspect. The meniscus are C-shaped cushions made of fibrocartilage. They help pad the knee during movement. Meniscal injuries and tears fall into two types - acute tears and chronic tears. Acute meniscal tears often occur from twisting injuries. Chronic meniscal tears are degenerative in nature and occur due to wear and tear.
Blood supply of the Meniscus
The reason meniscus tears are so problematic is because once torn, they don’t heal well. This has to do with their blood supply. When a structure in the body has good blood supply, it will heal quickly. Our bodies can deliver the nutrients it needs to repair the injured tissue. Structures with poor blood supply tend to heal much slower, if at all. This is true of meniscus injuries.
We categorize the blood supply of the meniscus into red and white zones. The red-red zone has excellent blood supply. The red-white zone has a moderate blood supply. The white-white zone has no blood supply. Because tears in the white-white zone have such poor blood supply, surgeons opt to cut them out.
History of Meniscus Tear Treatments
Orthopedic surgeons used to perform a total meniscectomy for patients with meniscus tears. This procedure involved taking out the entire meniscus. If you have a tear that causes you pain, why not remove it? This made theoretical sense. In practice, this proved to be a mistake. After the surgeons removed the padding between the bones, the bones rubbed against each other more. This led to increased degeneration and arthritis. This comes as no surprise. But back then, it seemed a viable treatment option.
The surgeons then tried taking out only the torn part of the meniscus. This is a partial meniscectomy. Arthroscopic partial meniscectomies are one of the most common procedures performed in the United States. But should they be?
Meniscus Tear Surgery Randomized Controlled Trials
Sihvonen et al (NEJM, 12/2013) published an eye opening study looking at arthroscopic partial meniscectomy versus sham surgery for degenerative meniscus tears. They had a total of 146 patients who had a meniscus tear confirmed during arthroscopy. They were then randomized in the operating room. 70 ended up with the actual surgery. 76 ended up with a sham surgery. During the sham surgery, the surgeons mimicked the process of the actual surgery. They asked for all the instruments, manipulated the knee, used suction, applied instruments against the knee, and kept the patient in the operating room for the same amount of time required to perform the actual surgery.
Researchers administered questionnaires at 2, 6, and 12 months after surgery. They found that the surgical group significantly improved at 12 months. What's shocking is that the sham group also significantly improved at 12 months. There was no statistical difference in any of the outcomes between the two groups. The surgical group was no better than the sham surgery group.
(At the end of the study, researchers asked all patients which group they thought they were in. Patients were unable to guess which group they belonged to.)
This trial is important as a sham surgery is the best placebo for a surgical procedure. The authors concluded: “the outcomes after arthroscopic partial meniscectomy were no better than those after a sham surgical procedure.”
The authors continued to follow these patients. They published their results from 2 years of follow up (Ann Rheum Dis, 2/2018). Here are the authors’ conclusions: “The outcomes after arthroscopic partial meniscectomy were no better than those after placebo surgery. No evidence could be found to support the prevailing ideas that patients with presence of mechanical symptoms or certain meniscus tear characteristics or those who have failed initial conservative treatment are more likely to benefit from arthroscopic partial meniscectomy.”
Mechanical Symptoms from Meniscus Tears and Arthritis
The researchers mention the presence of mechanical symptoms and meniscus tear characteristics. They do this because surgeons started using those as reasons to operate. If you have catching, locking, etc, you will benefit from surgery.
This was actually investigated by Thorlund et al (BJSM 3/2019). They conducted an observational study examining how often a meniscus tear was present during surgery when a patient reported mechanical symptoms. They had about 800 total patients in their data set. They found that “preoperative mechanical symptoms were equally prevalent in patients with and without a meniscal tear.”
The authors go on to conclude that “patient-reported mechanical symptoms were equally common irrespective of presence or absence of a meniscal tear in patients undergoing arthroscopy for suspicion of a meniscal tear. Our findings suggest that mechanical knee symptoms have a limited value when considering indication for meniscal surgery.”
Meniscus Tear Pain and Meniscus Tear MRI
Things get even more interesting. Just because you have a meniscus tear, doesn’t mean the tear is the cause of your knee pain. In fact, just because you have a meniscus tear, doesn’t mean you have knee pain at all. Culvenor et al (BJSM, 06/2018) published a systematic review and meta-analysis looking at the prevalence of meniscus tears on MRI. These patients had no knee pain and no history of knee injuries. They included 63 studies with a total of 5397 knees. They found that 19% of patients over 40 years old had meniscus tears. The older you are, the more likely you are to have a meniscus tear.
What does this mean? If we took 100 people without knee pain and took an MRI of their knee, 19 of them will have a meniscus tear. But none of them have any pain or symptoms. If an MRI shows a meniscus tear, it doesn't mean that is why you have pain. You could fall in the 19%. The meniscus tear is an incidental finding.
Meniscus Tear Treatment - Sham Surgery
Sihvonen et al (BJSM, 08/2020) actually followed their surgery vs sham patients out to 5 years. They concluded: “Arthroscopic partial meniscectomy was associated with a slightly increased risk of developing radiographic knee osteoarthritis and no concomitant benefit in patient-relevant outcomes, at 5 years after surgery.”
Here is a quick summary about degenerative meniscus tears.
Surgeons completely removed the meniscus when there was a meniscus tear. Patients didn’t do better. In fact, they got worse. They also had very high rates of arthritis.
Surgeons started removing only part of the meniscus. Patients didn’t do any better when compared to sham surgery.
Surgeons started telling patients that mechanical symptoms need surgery. Turns out that may not be correct either. Mechanical symptoms may not correlate with having a meniscus tear. (Note: recurrent obstruction or locking of the knee that doesn’t improve with conservative measures likely still needs surgery.)
Population studies show meniscus tears are common. 19% of people over 40 years old have meniscus tears. They had no pain. Having a meniscus tear on your MRI does not mean that is the cause of your pain.
Long term data shows removing part of the meniscus has no benefit in patient outcomes. It also leads to arthritis.
Non Surgical Meniscus Tear Treatment Options
So what are the non surgical options to treat meniscus tears? Physical therapy or home exercise programs as well as injections are great options.
Stensrud et al (BJSM, 12/2012) performed a cross sectional study looking at 82 participants with knee pain and MRI confirmed degenerative meniscus tears. They found that patients had significantly weaker quadriceps and lower extremity strength on their injured leg when compared to their non-injured leg. This supports treating meniscus tears with muscle strengthening and physical therapy.
This also makes sense. Weakness leads to biomechanical problems. These issues lead to increased wear and tear. All this results in pain. Addressing the biomechanics with strengthening will lead to resolution of pain.
Clinical trials also support physical therapy to treat meniscal injuries. Van de Graaf et al (JAMA, 08/2018) performed a randomized controlled trial of patients with nonobstructive meniscus tears comparing arthroscopic partial meniscectomy with physical therapy. They followed patients up to 2 years. Physical therapy was noninferior to surgery for improving patient reported knee function over the 2 year follow up period.
Systematic review and meta-analyses continue to arrive at the same conclusions. Lee et al (Clin J Sport Med, 05/2020) performed a systematic review and meta-analysis of randomized controlled trials comparing arthroscopic partial meniscectomy to physical therapy in patients with degenerative meniscus tears. They concluded that the literature “provides relatively strong evidence that [surgery] did not improve functional activity or reduce pain compared with the results with conservative treatment or sham operation in knees with mild or no osteoarthritis.”
Meniscus Tear Treatment Options - Injections
There is plenty of evidence that physical therapy benefits patients with meniscus tears. But what if patients are in so much pain that they cannot perform effective physical therapy? After all, it’s difficult to strengthen muscles if you are in pain. Rather than rushing to the operating room, there are many other options to try to decrease pain. Oral anti-inflammatory medications such as ibuprofen and naproxen can help decrease pain. Topical anti-inflammatory gels such as diclofenac can also help. Intra-articular knee injections can significantly decrease pain.
Cortisone injections have been around forever and can reduce pain. But their use is starting to fade away due to concerns for tissue toxicity.
Orthobiologics such as platelet rich plasma are an excellent option. Many clinical trials, systematic reviews, and meta-analysis support the use of orthobiologics especially if there is underlying mild to moderate knee osteoarthritis.
Don't jump straight to surgery for degenerative meniscus tears. Read through the evidence and make an informed decision about your health and your knee. Discuss with your doctor the best way to treat your pain.