Knee meniscus surgery: How long until you can start walking on it?

Todd Lloyd
April 6, 2023

A member of my family recently had arthroscopic knee surgery. She's a runner; she's an athlete. But she ran too hard one day last year. Battling the pain from a torn meniscus, we rightfully explored conservative low tech rehab, chirorpactic care, then physical therapy, and an MRI, but nothing stuck until it finally became time to do surgery.

Don't worry it went well. Surgery was done in Sonoma by Dr. Brown. He was great. The support staff was great.

Instructions were great too, but I still had questions.

I'm curious about meniscus surgery and the healing times involved. Let's be doctors who know the research. I'm thinking specifically about arthroscopic medial knee surgery.

Athletic patient in her early 40s. It was a debridement, not a repair. She's very complient with her rehab, so shes keeping her leg muscles strong and conditioned.

But what i want to know is how safe it is to start weight bearing activity. Can she walk on a treadmill desk for 8 hours? How do we know what is safe for the parts of the meniscus that do not have pain nerve endings?

As doctors familiar with the research, we can provide some general guidelines for patients recovering from arthroscopic medial knee surgery, specifically debridement. However, it's important to note that each patient's recovery process can vary, and a personalized approach based on individual factors is recommended.

In general, after a meniscus debridement, patients can often begin weight-bearing activities fairly quickly. As the meniscus was trimmed and not repaired, there is usually less concern about stressing the healing tissue. However, it's essential to follow a progressive rehabilitation program to minimize the risk of further injury.

For a compliant, athletic patient in her early 40s, it's encouraging that she is keeping her leg muscles strong and conditioned. In her case, weight-bearing activities like walking might be allowed within the first week after surgery, as long as she experiences minimal pain and swelling.

Regarding walking on a treadmill desk for 8 hours, it's best to gradually increase the duration and intensity of weight-bearing activities, as advised by her physical therapist or orthopedic surgeon. Starting with shorter intervals, such as 30 minutes to an hour, and gradually increasing the time spent on the treadmill desk may be more appropriate. The patient should be attentive to any pain or discomfort and should communicate any concerns with her healthcare team.

The parts of the meniscus with fewer pain nerve endings are indeed more challenging to assess. Monitoring overall knee function, stability, and any potential swelling can provide indirect indications of how well the meniscus is tolerating the weight-bearing activities.

In summary, although weight-bearing activities can typically be initiated soon after a meniscus debridement, it's essential to progress gradually and follow the guidance of the patient's healthcare team. Individual factors and responses to rehabilitation will dictate the appropriate timeline for resuming activities like walking on a treadmill desk for extended periods.

Pain sensitive parts of the meniscus

Can you tell me the different anatomical parts of the meniscus, and what parts are pain sensitive?

The meniscus is a C-shaped piece of fibrocartilage located in the knee joint, acting as a shock absorber and providing stability between the femur (thigh bone) and tibia (shin bone). There are two menisci in each knee – the medial meniscus (inner side of the knee) and the lateral meniscus (outer side of the knee).

The meniscus can be divided into three main parts:

  1. Outer (peripheral) zone: This zone is well vascularized, meaning it has a good blood supply. It is often referred to as the "red zone" due to its rich blood supply. The outer zone is more likely to heal after an injury because of this blood supply, and it is also the most pain-sensitive part of the meniscus, as it contains more nerve endings.
  2. Middle (transitional) zone: This zone, sometimes called the "red-white zone," has fewer blood vessels and nerve endings than the outer zone, making it less pain-sensitive. The blood supply and healing potential are also reduced compared to the outer zone.
  3. Inner (central) zone: The inner zone, or "white zone," is avascular, meaning it has little to no blood supply. It also has very few nerve endings, making it less sensitive to pain. Due to its limited blood supply, injuries in this zone are less likely to heal on their own, and surgical intervention might be necessary.

In summary, the outer zone of the meniscus is the most pain-sensitive due to its greater concentration of nerve endings, while the inner zone is the least pain-sensitive. The middle zone has an intermediate level of pain sensitivity.

Is it harmful to grind down on a meniscus?

If the inner zone is less pain sensitive, would someone unknowingly grind away at a tear without pain?

Yes, it is possible for someone to unknowingly exacerbate a tear in the inner zone of the meniscus without feeling pain. Because the inner zone has very few nerve endings and limited blood supply, it is less sensitive to pain. This means that individuals with a tear in this region might not experience significant pain or discomfort, which could lead them to continue their regular activities without realizing that they are causing further damage to the meniscus.

However, it's essential to note that even if pain is not present or is minimal, other symptoms can indicate a meniscal tear. These may include swelling, stiffness, reduced range of motion, a sensation of the knee "locking" or "catching," and general knee instability. If any of these symptoms are present, it's crucial to consult a healthcare professional for evaluation and management.

It is always better to address a potential meniscal tear early on, as ignoring the issue and continuing regular activities could lead to further damage and long-term complications, such as arthritis or reduced knee function.

How does a meniscus with no blood supply stay alive for 100 years?

Does the avascular parts of a meniscus recieve nutrients through imbibition, so it recieves nutrients through the pumping action of movement? Much like a spinal intervertebral disc?

Yes, that's correct. The avascular parts of the meniscus, primarily the inner zone, receive nutrients through a process called imbibition. Imbibition is the process by which the meniscal tissue absorbs nutrients from the synovial fluid in the joint space through compression and decompression cycles.

Similar to the process in intervertebral discs, the pumping action of movement facilitates the exchange of nutrients and waste products between the meniscus and the surrounding synovial fluid. When the knee joint is compressed during movement, the meniscus releases waste products and absorbs fresh synovial fluid containing nutrients, such as glucose and oxygen, necessary for tissue health and maintenance.

This process of imbibition is essential for the avascular parts of the meniscus, as it helps maintain the tissue's health and function despite the lack of direct blood supply. However, it's important to note that the limited nutrient supply and reduced cellular activity in the avascular region also contribute to its reduced ability to heal after an injury.

A trail running woman ascends Mt. Tam
A trail running woman ascends Mt. Tam

Intrigued by the inner workings of the knee, I sought to explore the meniscus, its healing, and the recovery journey. As we delved into the details of meniscus surgery, a specific case was shared – an athletic woman, in her early forties, who had undergone arthroscopic medial meniscus debridement.

In the pursuit of understanding, we questioned the safety of weight-bearing activities post-surgery, and how much was too much for a patient so diligent and dedicated. With debridement, we discovered, patients can typically return to weight-bearing sooner, as long as they experience minimal pain and swelling.

To walk on a treadmill desk for eight hours was the query at hand, but we found that a gradual approach was the better plan. Starting with shorter intervals and cautiously increasing the time, the patient's progress would be smoother, more secure, and simply sublime.

We then explored the meniscus' anatomy, where zones vary in sensitivity – outer, middle, and inner, each with a unique nerve-ending activity. The outer zone, rich in blood supply, is the most pain-sensitive part, while the inner zone, avascular and mysterious, is the least sensitive in contrast.

With the inner zone's reduced sensitivity, one could unknowingly exacerbate a tear, causing further damage without experiencing pain or discomfort to be aware. However, other symptoms like swelling, stiffness, or catching sensations could indicate a problem, urging the need for consultation and evaluation.

Indeed, the avascular parts of the meniscus receive nutrients through imbibition, similar to spinal intervertebral discs, and movement plays a significant role in maintaining the meniscus' condition. The pumping action of the knee, with compression and release, facilitates the exchange of nutrients and waste, offering the meniscus a moment of peace.

In the end, we unraveled the mysteries of meniscus care, from surgery to recovery, with the utmost attention to detail, dedication, and clarity. Each patient's journey is unique, but with guidance from healthcare professionals, a safe and sound recovery can be achieved, leaving them feeling strong, stable, and sensational.

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