Why Did My Meniscus Tear?

By an orthopedic surgeon who fixes a lot of knees—and spends even more time trying to protect the meniscus you were born with.

This is question that I get quite a lot in my office. For seemingly no reason at all my previously active and healthy patient has developed intermittent sharp pain at the inside of the knee. Where before they were playing tennis and pickleball, they now live in fear that even an uneven sidewalk could do them in for the day. These are often the signs of the dreaded meniscus tear.

Let's dive into it, shall we?

What the meniscus actually does

Each knee has two C-shaped pads of fibrocartilage—the medial and lateral menisci—that deepen the socket, share load, and stabilize the joint. Their unique “hoop stress” architecture spreads force like a belt under compression; when the ring is broken (think radial or root tear), pressures spike and cartilage pays the price. That’s why preserving or restoring the ring matters. PMC+1'

Blood supply 101: red-red, red-white, white-white

Only the outer third of the meniscus is well vascularized (the “red-red” zone), the middle third has sparse flow (red-white), and the inner third is largely avascular (white-white). Tears in blood-rich zones heal better and are more repairable; tears in avascular zones rarely heal, even when sutured. OrthoInfo+1

Who’s most at risk for degenerative meniscus tears?

Degenerative tears are frayed, complex, and often come on insidiously—very different from the “pop” of a young athlete’s bucket-handle tear.

• Age > 40–50: Meniscal tissue becomes drier, less cellular, and more brittle with time. OrthoInfo

• Obesity and metabolic load: Higher bodyweight increases meniscal strain and is linked to degenerative pathology on MRI. PMC

• Malalignment & knee geometry: Bow legged alignment predispose to medial compartment overload and degenerative tearing (including posterior root tears). PMC+1

• Occupational kneeling/squatting, twisting: Repetitive deep flexion and torsion elevate risk. ScienceDirect

• Pre-existing cartilage wear and prior ligament injury: Degeneration and instability raise stresses the meniscus must absorb. Arthroscopy Sports Medicine

Why meniscus repair becomes less desirable with increasing age

I love repairing menisci, but biology and tear pattern have to cooperate.

1. Vascular reality: Degenerative tears are more often in the inner, avascular zones; sutures here have low healing potential. OrthoInfo

2. Tissue quality: Frayed, delaminated collagen won’t hold stitches like youthful, longitudinal tears do. OrthoInfo

3. Joint environment: Coexisting chondral wear and low-grade synovitis inhibit healing biology. PMC

4. Evidence check: In middle-aged patients with degenerative tears, arthroscopic partial meniscectomy (APM) has repeatedly shown no meaningful advantage over sham surgery or structured physical therapy for pain and function. That pushes us away from “scope and trim” as a reflex—and toward rehab first. New England Journal of Medicine+1

Important nuance: in carefully selected patients ≥40 with repairable patterns (true peripheral longitudinal tears, some radial/root tears with anatomic repair), modern techniques can still do well. Patient selection is everything. PMC+1

What happens once the meniscus is torn?

• Increased Cartilage Contact Pressures: Losing circumferential fibers limits the effectiveness of the meniscus in cushioning the smooth articular cartilage. The more meniscus lost, the greater the contact pressures.PMC+1

  
  

• Osteoarthritis risk: Across high-quality data, meniscus tear size correlates linearly the with the accelerated development of osteoarthritis

  
  

• Biomechanics: As a result of the swelling in the knee and pain avoidance changes in the gait the meniscus tear can effectively cause other problems around the knee like knee cap pain and hamstring tendonitis.

My approach in clinic

1. Diagnose the pattern, not just “a tear.” Radial and root tears demand special attention; peripheral longitudinal tears are repair candidates. PMC

2. Start with high-value non-operative care for degenerative tears: load management, focused physical therapy (hip/gluteal strength, neuromuscular control), weight optimization, and occasional injections for inflammation. PubMed

3. Offer repair if possible when biology and pattern say it can heal (peripheral vascular zone, root repair with anatomic restoration) if the joint environment is favorable. PMC

4. Menisectomy with minimal resection to reduce contact pressures

Take-home for patients

• Protect the meniscus you have; you can’t grow a new one.

• Age, alignment, and load matter—control what you can (strength, weight, activity modifications).

• Surgery should preserve or restore the meniscal ring whenever possible

Dr. Barrett