Is running bad for your knees?

Generally, no activity is inherently horrible for cartilage; inactivity is worse. There's an inverted U-shaped curve for activity and cartilage health, meaning too much or too little can be detrimental, but moderate activity with good biomechanics is beneficial.

What is the long-term risk of arthritis after an ACL tear?

Roughly 50% of individuals who experience an ACL tear (reconstructed or not) show signs of arthritis within 15-20 years, suggesting that even with reconstruction, the initial joint insult significantly increases the risk.

What is an 'inflamma-type' patient after knee surgery?

An 'inflamma-type' patient is characterized by persistent elevated inflammatory markers (like IL-1 and IL-6) in their synovial fluid post-surgery, leading to chronic low-grade inflammation and potentially slower recovery.

Can ACL tears be prevented, especially in females?

While difficult, injury prevention programs focusing on neuromuscular control, such as proper landing mechanics (avoiding valgus knee and adducted hip), can help reduce ACL tears. Females may have a higher risk due to factors like delayed neuromuscular maturation.

When should a meniscus tear be repaired vs. trimmed?

In younger patients without arthritis, meniscus tears, especially peripheral ones with good blood supply or bucket handle tears, should ideally be repaired. Tears associated with advanced arthritis are often trimmed, as repair may not improve outcomes.

What is the typical recovery timeline for a total knee replacement?

Recovery for a total knee replacement is a long process, often taking up to a year for significant improvement. While some patients feel much better within months, others continue to improve gradually beyond the one-year mark.

How much does excess body weight contribute to knee arthritis?

Excess body weight significantly drives knee arthritis. Losing even a small amount of weight can substantially reduce the load on the knee (e.g., 5 lbs off can take hundreds of pounds of cumulative pressure off the knee daily), potentially delaying or avoiding the need for replacement.

Key Moments

Knee anatomy, pain, & treatment | Peter Attia & Adam Cohen

Peter Attia MD

Science & Technology3 min read54 min video

Aug 3, 2023|30,580 views|714|36

knee knee anatomy pain treament adam cohen peter attia

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Key Moments

TL;DR

Understanding knee anatomy, how activity affects cartilage, ACL injury risks, and treatment options including surgery and replacements.

Key Insights

The knee joint is inherently more unstable than the ball-and-socket hip joint, relying on ligaments and menisci for stability and force distribution.

Inactivity is detrimental to cartilage health; moderate activity stimulates chondrocytes, but excessive or poorly aligned forces can accelerate degeneration.

ACL tears significantly increase the long-term risk of arthritis, as joint mechanics and load distribution are permanently altered, even after reconstruction.

ACL injury prevention programs show a high 'number needed to treat' (90:1) but can reduce risks for various injuries by improving neuromuscular control, especially in females.

Meniscus tear treatment depends on tear type, location, and the presence of arthritis; repair is preferred for young individuals with intact cartilage, while debridement may be used for degenerative tears or severe arthritis.

Total knee replacement is indicated for advanced arthritis impacting multiple compartments after conservative treatments fail, with recovery taking up to a year and limitations on high-impact activities.

KNEE ANATOMY AND JOINT STABILITY

The knee joint, unlike the stable ball-and-socket hip, is inherently less stable. It comprises the patella (kneecap), quadriceps and patellar tendons, ligaments (ACL, PCL, collateral ligaments), and menisci. Cartilage covers the bone ends, facilitating smooth movement; its preservation is crucial. The menisci, semicircular structures, distribute about 30% of the knee's load and protect the articular cartilage from degeneration.

EFFECTS OF ACTIVITY AND BIOMECHANICS ON CARTILAGE

Inactivity is harmful to cartilage, leading to matrix breakdown. Conversely, chondrocytes (cartilage cells) respond positively to stress by producing more matrix. However, there's an inverted U-shaped curve: excessive or improperly aligned forces can accelerate cartilage wear. Good biomechanical alignment, where a line from hip to ankle passes through the knee's center, is key to preventing this degeneration. Poor alignment, like 'knock knees' or 'bow legs,' concentrates force on specific knee compartments.

ACL INJURIES AND LONG-TERM OUTCOMES

Anterior Cruciate Ligament (ACL) tears, common in non-contact injuries particularly among females due to neuromuscular control factors, significantly increase the risk of developing arthritis. Even with reconstruction, altered joint mechanics lead to greater compressive forces on cartilage. Studies indicate that within 15-20 years, about half of individuals with ACL tears, regardless of reconstruction, show signs of arthritis. While reconstruction protects the meniscus and allows for desired activities, it doesn't fully restore normal joint load distribution.

MENISCUS TEARS AND TREATMENT CONSIDERATIONS

Meniscus tears are addressed based on their type and the joint's condition. Peripheral tears with good blood supply can often be repaired (sewn back together). Tears that displace, like bucket-handle tears, may lock the knee and require repair. Radial tears or degenerative tears in an arthritic knee might necessitate trimming the torn portion (meniscectomy). For young individuals with a meniscus tear and no arthritis, repair is strongly considered to prevent future degeneration.

PATEL-FEMORAL PAIN SYNDROME AND CONSERVATIVE MANAGEMENT

Patellofemoral pain syndrome, often caused by overloading the kneecap during activities like running or squatting, results in anterior knee pain. While quadriceps strengthening is a common treatment, it can sometimes exacerbate pain due to increased load on the patella. Treatment may involve hip strengthening, focusing on the gluteus medius, to improve overall leg alignment and reduce stress on the kneecap. Blood flow restriction (BFR) training can offer a lower-load alternative for muscle strengthening.

TOTAL KNEE REPLACEMENT: INDICATIONS AND RECOVERY

Total knee replacement is reserved for advanced arthritis affecting multiple knee compartments when conservative treatments (PT, injections, bracing) have failed and quality of life is significantly impacted. The surgery involves replacing the damaged joint surfaces with prosthetic components, aiming for improved alignment. Recovery is a lengthy process, often taking up to a year for full improvement in the majority of patients. While allowing for many activities, high-impact or contact sports are generally discouraged due to the risk of implant failure or fracture.

Mentioned in This Episode

●Supplements

●Products

●Tools

●Concepts

●People Referenced

Knee Pain Management: Dos and Don'ts

Practical takeaways from this episode

Do This

Maintain cartilage through appropriate activity; inactivity is detrimental.

Ensure good mechanical alignment from hip to ankle through the knee.

Consider meniscus repair for young individuals without arthritis.

If you have arthritis and a meniscus tear, conservative treatment is often the first step.

For patellofemoral syndrome, focus on hip strengthening (gluteus medius) and consider BFR for quads if needed.

Weight loss is crucial for reducing knee load and potentially avoiding knee replacement.

Allow approximately one year for full recovery after a total knee replacement.

Avoid This

Avoid excessive forces on the kneecap without proper mechanics.

Do not ignore knee instability, as it increases arthritis risk.

Avoid aggressive meniscal surgery in cases of advanced arthritis; sham surgery outcomes are similar.

Do not rush into surgery if the knee is inflamed; wait for it to quiet down.

Avoid high-impact contact sports after a total knee replacement.

Do not expect immediate full recovery post-knee replacement; it's a long process.

Knee Force Amplification During Activities

Data extracted from this episode

Activity	Force Multiplier (Body Weight)	Location of Force
Squatting (regular)	7x	Behind kneecap
Running	8x	Knee (general)
Walking up stairs	4x	Knee
Walking down stairs	7x	Knee

ACL Reconstruction Graft Options and Considerations

Data extracted from this episode

Graft Type	Pros	Cons	Ideal Candidate
Patellar Tendon (autograft)	Bone-to-bone healing, gold standard	More painful recovery, kneeling pain	Active individuals, athletes
Hamstring Tendon (autograft)	Easier recovery up front	Weaker hamstrings, potential for re-rupture risk	Less active individuals, those prioritizing comfort
Quadriceps Tendon (autograft)	Emerging option, less research	Less established compared to patellar or hamstring	Limited data
Allograft (cadaver)	Avoids donor site morbidity	Higher re-rupture risk, slower tissue maturation	Patients over 34, less active individuals

Common Questions

The knee joint includes the patella (kneecap), quadriceps tendon, patellar tendon, tibia, femur, and crucial ligaments like the ACL, PCL, MCL, and LCL. It also contains menisci for force distribution and cartilage for smooth movement.

Topics

Health & Longevity Human Performance Joint Health Sports Injuries Knee Anatomy ACL Reconstruction Meniscus Tears Total Knee Replacement

Mentioned in this video

toolcomputer navigation

Technology used during knee replacement surgery to ensure precise cuts and alignment.

toolfibula

The smaller bone on the outside of the lower leg.

conceptposterior cruciate ligament

Another major ligament in the knee that provides stability.

conceptmenisci

Two semicircular structures in the knee that distribute force and protect cartilage.

conceptsemimembranosus

A hamstring muscle located on the inner side of the thigh.

toolmeniscectomy

Surgical procedure to trim away torn pieces of the meniscus.

concepttibial plateau

The top surface of the tibia, part of the knee joint.

personAdam Cohen

An orthopedic surgeon discussing knee anatomy, injuries, and treatments.

toolmeniscus repair

Surgical procedure to sew a torn meniscus back together.

conceptacetabular impingement

Abnormal contact between the femoral head and the acetabulum, leading to pain and arthritis.

conceptpatella

The kneecap, a rounded bone at the front of the knee joint.

conceptcartilage

The smooth, slippery tissue covering the ends of bones in joints, crucial for joint health.

conceptmedial collateral ligament

A ligament on the inner side of the knee.

conceptgracilis

A muscle in the inner thigh often harvested with the semitendinosis for ACL reconstruction.

conceptanterior cruciate ligament

A key ligament in the knee that provides stability, commonly torn.

conceptlateral collateral ligament

A ligament on the outer side of the knee.

conceptIL-6

Interleukin-6, an inflammatory marker.

conceptbiceps femoris

A hamstring muscle on the outer side of the thigh.

toolBlood Flow Restriction (BFR)

A technique used during exercise to enhance muscle hypertrophy and strength at lower loads.

toolkinematic knee replacement

A type of knee replacement that aims to maintain the natural alignment of the leg.

conceptglenohumeral joint

The main joint of the shoulder.

personPeter Attia

Host of the podcast, interviewing Dr. Cohen on knee health.

conceptpatellar tendon

The tendon connecting the patella to the tibia.

supplementIL-1

Interleukin-1, an inflammatory marker.

supplementPlatelet-Rich Plasma (PRP)

A regenerative therapy that uses a concentration of platelets from the patient's own blood to promote healing.

conceptACL tear

A common knee injury involving the anterior cruciate ligament, significantly increasing arthritis risk.

tooltibia

The larger bone in the lower leg, forming the platform of the knee joint.

conceptbucket handle tear

A severe type of meniscus tear where a segment flips, potentially locking the knee.

conceptgluteus medius

A key hip abductor muscle important for stability and preventing knee valgus.

supplementHyaluronic Acid

A substance injected into the joint to lubricate and cushion, often used for osteoarthritis.

producthigh molecular weight polyethylene

The plastic material used for the tibial bearing surface in knee replacement implants.

conceptshoulder dislocation

Displacement of the humerus from the glenoid cavity, increasing arthritis risk.

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