For many people we see, when given a choice, they would prefer not to have a meniscus surgery. For others, they may have no choice. They have a meniscus injury that prevents them from bending or straightening their leg and is causing them a lot of pain. But is surgery the only option?
The medical research of the last few years have made it clear that the old guidelines that the only treatment for a meniscus was to remove damaged tissue by way of an arthroscopic meniscectomy or partial meniscectomy (the whole or partial removal of the meniscus) needed to be revised and replaced by a new medical thinking of how to treat meniscus tears. This was illustrated by an international group of researchers who wrote in December 2021 in the Journal of experimental orthopaedics (1) that the future of meniscus treatments should focused on the doctor’s ability to save the meniscus. These new guidelines would include the use of orthobiologics, treatments from the cells of the patients.
The patient with many meniscus surgeries and a prognosis of eventual knee replacement
Like many in our field, we see patients who have had numerous arthroscopic surgeries. Sometimes these patients even brag about how many surgeries they had. Most will stop bragging once they learn that they will ultimately need a knee replacement and that the activities or work they did/do that accelerated their meniscus problems will most likely come to an end because the knee replacement will not allow them the range of motion needed to continue on.
For the patient who has had numerous surgeries, eventually many will report that the last surgery left nothing remaining to repair. A meniscectomy was performed and now the “count down” had begun to knee replacement. I will stop here to answer the question that we are asked the most. Is there any treatment that will regrow meniscus tissue. The answer is yes, however, the reality of the situation is that these treatments, namely orthobiologics such as platelet rich plasma and stem cell therapy cannot grow a meniscus from nothing. They can help however repair a damaged meniscus. These treatments are explained below along with other conservative care treatments. Many people have also asked us about biological 3D cellular printing of a new meniscus. This technology while promising and exciting is many, many years away.
Meniscus transplant surgery – “does not replicate a normal meniscus”
The idea of repairing the meniscus is further strengthen by the limited success of Meniscal allograft transplantation or more simply, a meniscus transplant from a human donor. In December 2020, an editorial in the medical journal Arthroscopy (2) provides a realistic assessment of the meniscus transplant surgery outcome.
“Meniscal allograft transplantation for symptomatic knees after meniscectomy decreases pain and often improves function, but it does not replicate a normal meniscus. The ability of to delay arthritic changes is an ongoing area of study, and it is known that outcomes and graft survivorship deteriorate with longer follow-up. Recommended indications are symptomatic patients after meniscectomy with mild (or at most moderate) degenerative changes and absence of (or surgically corrected) associated malalignment or ligament deficiency. When these indications are followed, 80% of patients improve, with survivorship of 83% at 10 years and 56.2% at 20 years.
Once a meniscus is removed or partially removed, it is very difficult to grow, transplant, or make a new one.
In trying to understand “clinical replacement strategies for meniscus tissue deficiency,” researchers wrote (3) in November 2021: “Meniscus tissue deficiency resulting from primary meniscectomy or meniscectomy after failed repair is a clinical challenge because the meniscus has little to no capacity for regeneration. Loss of meniscus tissue has been associated with early-onset knee osteoarthritis due to an increase in joint contact pressures in meniscectomized knees. Clinically available replacement strategies range from allograft transplantation to synthetic implants, including the collagen meniscus implant, ACTIfit, and NUSurface. Although short-term efficacy has been demonstrated with some of these treatments, factors such as long-term durability, chondroprotective efficacy, and return to sport activities in young patients remain unpredictable. Investigations of cell-based and tissue-engineered strategies to treat meniscus tissue deficiency are ongoing.” Once a meniscus is removed or partially removed, it is very difficult to grow, transplant, or make a new one.
The knee needs a meniscus
Because doctors once thought that the meniscus was unrepairable once damaged, (this is explained further below) the only option was to remove the damaged portion. As the decades of arthroscopic surgery outcomes were examined, it became very apparent removing the meniscus was a less than good choice for the long-term over health of the patient’s knee.
A June 2021 research paper (4) summarizes the knee’s need for a meniscus this way.
“The meniscus plays an important role in the knee joint, as it plays a role in shock absorption and transmission, joint stabilization, proprioception, lubrication and nutrition of the articular cartilage. Biomechanical studies have shown that a loss of meniscal integrity leads to changes in kinematics and loading of the knee joint. Even a loss of only 15–34% of the meniscus tissue increases the load on the hyaline cartilage by up to 350%.”
In other words, even the removal of a small amount of meniscus will result in a “crushing effect” on the remaining articular cartilage. The bone-on-bone degenerative process has now been accelerated.
The change in medicine towards meniscus repair
A repair is a repair and there are many ways to achieve a repair. What should be pointed at is that the body itself is always trying to repair the meniscus and sometimes simple rest may help this process. But then why then was meniscectomy the main treatment option for a badly damaged meniscus if the body was trying to repair the tissue itself? It comes down to the zones. The meniscus is divided and designated into zones by doctors. The zone that can heal and be repaired, the zone that cannot heal and be repaired, or so it was thought.
Red and white zones
In a recent study, (5) doctors explained the concept of meniscus zones that can heal and be repaired, the meniscus zones that cannot heal and be repaired.
“The repair of meniscus tissue in the avascular zone (the White Zone) remains a great challenge, largely owing to their limited healing capacity (or the lack of blood supply, that is why the zone is white).” The researchers continued: ” A comprehensive review of the literature suggests that MSCs possess an intrinsic therapeutic potential that can directly and indirectly contribute to meniscus healing.”
People with meniscus tears are very familiar with the terms “White Zone” and “Red Zone.” The “Red Zone,” represents the outer edges of the meniscus. It is called the red zone because blood circulates through it brining nutrients and healing elements. For those with a meniscus injury that is being recommended to surgery, you may have had your doctor explain to you that you have a “White Zone” tear. The “White Zone” lies in the center of the meniscus. It does not have a well organized blood network. It is these meniscal injuries that send patients to surgery.
The meniscus and articular cartilage try to save and heal each other
Researchers have noted a fascinating relationship between the meniscus and the articular cartilage of the knee. The articular cartilage is the cartilage covering at the base of the thigh bone and the top of the shin bones. The word fascinating comes from an October 2020 research paper (6) with the title “The menisci and articular cartilage: a life-long fascination.” Here the researchers explained that the “menisci and articular cartilage of the knee have a close embryological, anatomical and functional relationship, which explains why often a pathology of one also affects the other. Traumatic meniscus tears should be repaired, when possible, to protect the articular cartilage.”
The problem for patients is that despite the desire to heal and regenerate, as pointed out by University of Iowa researchers in their 2017 paper, “Serious meniscus injuries seldom heal and increase the risk for knee osteoarthritis; thus, there is a need to develop new reparative therapies. In that regard, stimulating tissue regeneration by autologous stem/progenitor cells has emerged as a promising new strategy. (7)
When surgery removes too much meniscus
People may have significant knee pain after meniscus surgery because too much meniscus removed. This problem is described in a September 2021 paper presented in the Sports medicine and arthroscopy review.(8)
“Certain (meniscus tear injuries) are often treated with arthroscopic partial meniscectomy, which can effectively relieve symptoms. However, removal of meniscal tissue can also diminish the ability of the meniscus to dissipate hoop stresses (weight bearing pressure on the outside of the meniscus), resulting in altered biomechanics of the knee joint including increased contact pressures.”
“Altered biomechanics of the knee joint including increased contact pressures” describes a situation of accelerated knee osteoarthritis. This can be where the more pain after surgery is coming from. What may occur is that the surgery removed a portion of the meniscus to alleviate the patients pain. In doing so, the surgery made the meniscus smaller in size and compromised and weakened the meniscus’ ability to provide the needed cushion Nature designed it for.
Arthroscopic partial meniscectomy for someone over 50 is controversial
We will now begin our focus on the non-surgical options. I see many new patients with meniscus injury who are exploring second opinions. For some people they will be told that they will need to have surgery because the problem of their meniscus is indeed not repairable by any other means. For other who were told the meniscus surgery should be strongly considered, we can help many, not all, of these people avoid this surgery. For others their meniscus injury is not bad enough to warrant a surgery and they can be helped with injections.
A paper in the American Journal of Sports Medicine explains this further: (9)
“There is controversy about the benefit of arthroscopic partial meniscectomy for degenerative lesions in middle-aged patients.” In this study the doctors compared patient satisfaction with their arthroscopic partial meniscectomy in middle-aged patients with no or mild knee osteoarthritis and a degenerative meniscal tear and those with a traumatic (acute incident) tear. To achieve the study results, these patients were monitored for five years.
- Baseline patient characteristics were not different between groups. At the 5-year evaluation, the satisfaction rate in the traumatic and degenerative groups was 68.5% versus 71.3%, respectively. (Almost one-third or patients were dissatisfied with their surgical outcomes five years later).
- Patient satisfaction was significantly associated with functional outcomes.
- In the degenerative knee group, 37.4% had osteoarthritis progression to more advanced osteoarthritis.
- Conclusion: Who was more likely to have less than hoped for results of their arthroscopic knee surgery?
- Obese patients
- and patients with lateral meniscal tears.
- The researchers summarized who would likely be good candidates for surgery: Middle-aged patients with degenerative meniscal tears, without obvious osteoarthritis, and with failed prior physical therapy.
1 DePhillipo NN, LaPrade RF, Zaffagnini S, Mouton C, Seil R, Beaufils P. The future of meniscus science: international expert consensus. Journal of Experimental Orthopaedics. 2021 Dec;8(1):1-7.
2 Carter T. Editorial Commentary: Medial and Lateral Meniscus Allografts Using Bone Plug Fixation in Patients Without Advanced Arthritis Have 80% Positive Outcomes at 10 Years.
3 Wang D, Gonzalez-Leon E, Rodeo SA, Athanasiou KA. Clinical Replacement Strategies for Meniscus Tissue Deficiency. Cartilage. 2021 Nov 20:19476035211060512. doi: 10.1177/19476035211060512. Epub ahead of print. PMID: 34802295.
4 Yang CP, Hung KT, Weng CJ, Chen AC, Hsu KY, Chan YS. Clinical Outcomes of Meniscus Repair with or without Multiple Intra-Articular Injections of Platelet Rich Plasma after Surgery. Journal of Clinical Medicine. 2021 Jan;10(12):2546.
5 Hana Yu, Adetola B Adesida and Nadr M Jomha1. Meniscus repair using mesenchymal stem cells – a comprehensive review.Stem Cell Research & Therapy 2015, 6:86 doi:10.1186/s13287-015-0077-2
6 Kopf S, Sava MP, Stärke C, Becker R. The menisci and articular cartilage: a life-long fascination. EFORT Open Reviews. 2020 Oct;5(10):652-62.
7 Seol D et al. Characteristics of meniscus progenitor cells migrated from injured meniscus. J Orthop Res. 2016 Nov 3. doi: 10.1002/jor.23472.
8 Bedrin MD, Kartalias K, Yow BG, Dickens JF. Degenerative Joint Disease After Meniscectomy. Sports Medicine and Arthroscopy Review. 2021 Sep 4;29(3):e44-50.
9 Lizaur-Utrilla A, Miralles-Muñoz FA, Gonzalez-Parreño S, Lopez-Prats FA. Outcomes and patient satisfaction with arthroscopic partial meniscectomy for degenerative and traumatic tears in middle-aged patients with no or mild osteoarthritis. The American journal of sports medicine. 2019 Aug;47(10):2412-9.