The NBA season opened up this week without the New Orleans Pelicans rookie sensation Zion Williamson. Sportingnews.com reported Williamson underwent arthroscopic surgery for a torn lateral meniscus and will be out for 6 to 8 weeks. I have no personal knowledge of the specifics of his injury and resultant surgery but during my 32 years as head athletic trainer for the Los Angeles Lakers meniscus tears were considered an occupational hazard. This blog will give you an overview of what is the function of the meniscus, how is it injured and a general timeline for return to play for an NBA player.
The menisci are crescent-shaped pieces of fibrocartilage that sit between the femur (thigh bone) and the tibia (shin bone)…they form a cup on the tibia for the femur to fit into. The menisci function as shock absorbers as well as wedges between the bones to provide stability to the knee joint and are integral for load transmission. To preserve the life of the joint it is extremely important to retain as much of the menisci as possible post injury/surgery. Studies have shown that a normal knee has a shock-absorbing capacity 20% greater than a knee that has undergone a meniscectomy. It has also been reported that 50% of the load in the medial compartment (towards the midline of the body) and 70% of the load in the lateral compartment (towards the outside of the body) are transmitted through the menisci.
Statistically, the medial meniscus is injured more often than the lateral meniscus. The reason for this is that the medial meniscus is attached to medial collateral ligament which reduces is ability to move under extreme loads. The frequency of medial vs lateral meniscus tears became the topic of discussion in the Lakers training room one night after a game. Our team physicians were surprised when I expressed my experience was that there were more lateral meniscus tears than medial meniscus tears in the NBA. That prompted a look at 21 years of the NBA longitudinal injury surveillance system. We co-authored a 2011 study published in the American Journal of Sports Medicine: Epidemiology of Isolated Meniscal Injury and its Effect on Performance in Athletes From the National Basketball Association. We identified 129 isolated meniscal tears in the NBA. From this number, 77 (59.7%) involved lateral meniscus and 52 (40.3%) the medial meniscus. Left vs right were equal with more injuries occurring in games over practice.
We know the two things that the body doesn’t like are eccentric load (deceleration) and torque (turning). That is the exact mechanism of injury for a meniscus tear. Most athletes describe planting a foot and changing directions which puts tremendous torque on the meniscus.
Surgeons and radiologists name meniscus tears by their shape and location. But the more important characteristics are whether they are stable, unstable or are in a location that has a good blood flow (vascular). These are the characteristics that determine partial meniscectomy, non-surgical healing or surgical repair. The size of the tear, pattern of the tear, your age, health and activity level are all considerations of whether your doctor recommends rest, repair or meniscectomy.
An ideal situation to a not so ideal injury is to have the tear on the periphery of the meniscus. This area has blood flow which gives the body a chance to heal the tear. Depending on the grade of tear the surgeon will choose between immobilization over repair. Repair requires arthroscopic surgery to suture the torn area of the cartilage. Generally speaking, return to play is 4 to 6 months. This is significantly longer than meniscectomy but the longer recovery time pays dividends in the life of the joint preventing premature osteoarthritis.
If the meniscus cannot be repaired the surgeon will have to trim the torn part of the cartilage trying to retain as much of the meniscus as possible. There are cases of professional athletes returning to play as early as 2 to 3 weeks but these are few and far between and probably not a good idea. A more realistic return to play is 4 to 6 weeks and maybe even 6 to 8 weeks.