Meniscus tears – current understanding of function and rehabilitation
A meniscus injury – everyone would like to walk away from one (pun intended). We need our knees day in and out, and for the sporty people out there it might be a bit of a testing process to recover from such an injury. But, fear not! We’re here to guide you through the fundamentals that you need to know; from basic anatomy to the function of the meniscus and what the best evidence-based possibilities are for your successful rehabilitation.
Basics 101 – anatomy, function and limitations
Before we take a deeper dive into the anatomy and function of our knee meniscus, let’s concern three interesting details first:
- The word meniscus origins from the greek word me-niskos, meaning “crescent,” which in short means mēnē, meaning “moon”. 🌜
- The meniscus develops its characteristic shape already in the 8th – 10th week of pregnancy.
- For a long time, scientists considered the meniscus to be pretty functionless and were often generously removed via surgery. By the end of this article, you’ll see why this shouldn’t be the standard anymore.
Our knee joints consist of two moon-shaped and collagen-rich menisci (plural for meniscus), which are anchored on our shin bone (tibial plateaus) by the meniscofemoral and transverse ligaments and between our thigh bone (femoral condyle) (see Figure 1 and 2). The surfaces of the lateral and medial meniscus slightly differ, with the lateral meniscus covering a larger surface in comparison to the medial meniscus (Clark and Ogden 1983).
Figure 1: Anatomy of meniscus, view of the tibial plateau transverse Figure 2: Frontal view of knee joint
A knee joint is highly dependent on healthy menisci; they act as shock & force distributors during flexion and extension and as joint stabilisers. They help protect the joint cartilage and assist with proprioception (‘where the knee is in space’), and they also provide lubrication and nutrition to the knee joint, which is provided by the surrounding blood vessels and internal joint fluid, called the synovial fluid (Fox et al. 2012).
Now, we might think that the menisci are provided with a lot of blood flow – but here comes the pitfall; during our lifetime, the blood supply to our menisci gradually decreases from the inside out. While Travascio and Jackson (2017) found that this lack of blood supply does not necessarily lead to meniscal degeneration, it does hinder their availability of self-repair after an injury. And an injured meniscus can substantially alter the biomechanics of the knee and therefore cause us trouble in our movement patterns.
Traumatic vs. non-traumatic meniscus tears
Generally, we see two different types of meniscal injury in practice; non-traumatic and traumatic. The gold standard to detect a meniscal tear is via MRI.
Patients with a non-traumatic injury, report a gradual increase in complaints together with locking and catching sensations of the knee, a feeling of knee instability and subtle but consistent knee pain, particularly around the joint line (Ghislain et al. 2016). The estimated amount of non-traumatic meniscus injuries lies around 850’000 cases a year and affects often the more middle-aged and elderly population, with men being 2.5 more likely affected at around 40 – 50, and women from 60 to 70 (Luvsannyam et al. 2022). The nature of these injuries can be a result of higher age in combination with repetitive and work-related micro-traumas such as squatting and kneeling (Snoeker et al. 2013). Often, patients only gain awareness of their knee complaints after increasing their level of (sports) activity. That being said, Englund et al. (2008) found that among 991 subjects, 61% with identified non-traumatic meniscus tears were not showing any symptoms or pain in their daily life. Of subjects reporting knee pain, 63% showed meniscus tears.
For the ones with an acute traumatic meniscus tear, the situation looks a bit different. Such injuries are well-known in the younger and more sportive populations and the incidence leads to 2 in 1000 people in the Netherlands alone. Twisting, cutting and jumping movements whilst keeping the leg extended and the foot planted on the ground is the dominant mechanism of injury, as seen in rugby, football, skiing or basketball. The link between ACL injuries and meniscal tears is also well documented; waiting for 12 months or longer to treat an ACL injury can increase the risk of a medial meniscus tear. Additionally, meniscus tears are very likely (>80%) to occur in the above-mentioned sports in combination with an ACL tear (Stone et al. 1990, Hagino et al. 2015, Luvsannyam et al 2022). Symptoms of an acute tear are often immediate sharp pain, swelling and reduced range of motion. The type of tear then also determines the treatment approach and the likelihood of experiencing consistent pain and limitations. In broad terms, we can differentiate between vertical, radial and horizontal tears.
Surgical treatment of meniscal tears – what are the arguments for it?
Patients with both non-traumatic and traumatic meniscus tears are at a higher risk of knee osteoarthritis Karia et al. 2019, Bhan 2020). A partial meniscectomy (partial removal of the meniscus) is one of the most common orthopaedic surgeries worldwide, often performed in the middle-aged population with non-traumatic and degenerative changes of their meniscus.
However, the latest research has clearly outlined that meniscal surgery has no advantage to quality of life or knee function in comparison to non-surgical alternatives, such as physical therapy. Sihvonen et al. (2020) compared partial meniscectomy to placebo or sham surgery and found no evidence of better clinical outcomes after surgery. Instead, they found an even higher risk for osteoarthritis post-surgery.
There is an ongoing debate about whether partial meniscectomy in a younger population with acute meniscus tears yields better functional knee outcomes than conservative treatments. Pihl et al. (2018) demonstrated that in 150 younger patients aged 40 or less, they had significant and good functional knee scores 1-year post-surgery. Norduyn et al. (2022) demonstrated that meniscus surgery does not lead to a promising gain in normal knee function and physiotherapeutic treatment should be the first and initial treatment approach. Van der Graaff et al. (2022) found that patients younger than 40 who received surgical treatment first had similar knee outcomes and symptoms two years post-surgery compared to those who received physiotherapy first with the option of surgery at a later stage. 95% of patients assigned to physical therapy only never underwent partial meniscectomy.
Our treatment approach
In patients with acute traumatic meniscal tears, the first priority is to reduce swelling, restore full ROM (range of motion) for extension and flexion, and increase glute, quadriceps and calf strength, as well as proprioception, coordination and unilateral leg strength. Our end goal is your full and safe return to your daily activities and sports. We will create a program matching your daily life, taking into account the sport that you love to do, your work and your private life. We will guide you during our sessions whilst fine-tuning along the way. Our goal is to discharge you with more knowledge about the injury than when you came in, so that when pain or discomfort comes back – you know what to do and are not dependent on us first-hand.
In patients with non-traumatic meniscal tears, the main goal is to maintain and improve knee range of motion and increase glutes, quadriceps and hamstring and calf strength, as well as unilateral leg strength and proprioception and coordination.
To measure your strength gains, we use several strength tests such as force plates where we can test the external force – and therefore your strength – implied on your lower limbs. We design and follow a specific and functional training approach and work in close collaboration with the specialists at Xpert Clinics Orthopaedics. This way, we create short communication channels so that when we need assistance for you from Xpert Clinics, we can get easily in contact without you having to wait for 4 weeks before an appointment or answer.
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