Meniscus repair

Repair puts sutures across a tear and leaves the meniscus in the knee. The mechanical argument for it is direct, and it was made in cadaver knees forty years ago: repairing a peripheral tear left contact area and peak local contact stress where they had been, whichever suture technique was used, while resecting that same segment raised peak local contact stress about 110%.

Repair does not restore the intact joint, though, and the more recent simulator work says so plainly. An inside-out mattress repair of a large radial tear did not put the peak-pressure location back where the intact knee had it. Partial meniscectomy of the same tear then added more pressure on top — so the ordering is intact, then repaired, then resected, and repair sits in the middle rather than at the top.

Which tears are even repairable

Blood supply decides. Only the peripheral 10-25% of the meniscus is reached by the perimeniscal capillary plexus; everything inside that is avascular, and the posterolateral segment beside the popliteal tendon has neither penetrating vessels nor a synovial fringe. That anatomy is where the red-red, red-white and white-white zones come from, and it is why a peripheral vertical tear in a young knee gets offered sutures and a central horizontal flap in a sixty-year-old does not.

The trade, quantified

Repair fails more often than resection needs revising. In a systematic review restricted to traumatic tears in previously uninjured knees, reoperation followed 1.4% of partial meniscectomies at short-term follow-up and 3.9% at long term, against 16.5% and 20.7% after isolated repair. Pooled across thirteen studies with at least five years of follow-up, the meniscal repair failure rate — reoperation or clinical failure together — was 23.1%, or 131 of 566 repairs, and it stayed between 20.2% and 24.3% across every subgroup the review could define: medial or lateral, intact or reconstructed cruciate, whichever technique.

Repair is followed by less arthritis. A meta-analysis of twenty studies and 31,783 patients with acute tears found less advanced knee osteoarthritis after repair at about four years, and less progression to knee arthroplasty. In the same analysis, mean joint space width did not separate, IKDC did not separate, and the resection arm actually had the higher Lysholm score. Those results point different ways, and the authors report all of them.

Two things about a repair improve its odds. It fails less often when it is done alongside an anterior cruciate ligament reconstruction, and lateral repairs fail less often than medial ones.

Root tears, where the gap is widest

A posterior root tear detaches the meniscus from its bony anchor. Mechanically that is closer to removing the meniscus than to tearing it: the hoop is de-tensioned, and the tissue stops carrying load even though it is all still there.

Pooling studies with at least four years of follow-up, Kellgren-Lawrence progression occurred in 18 of 82 knees (22%) after medial posterior root repair and 41 of 62 (66%) after meniscectomy. Conversion to total knee arthroplasty followed in 9.8% and 36%. Postoperative IKDC scores did not separate. A second review of thirteen studies found the same shape — the change in Lysholm favoured repair, the change in Tegner did not, and severe postoperative osteoarthritis and reoperation were both less frequent after repair.

In 48 knees with a root tear and moderate osteoarthritis followed for about four and a half years, 3.3% of repaired knees and 33.3% of observed knees went on to a total knee replacement. Read that one with its baseline in mind: the knees that got repaired started with worse symptom and quality-of-life scores, which flatters their improvement figures while making the arthroplasty gap harder to explain away.

A Markov model built on this literature projects osteoarthritis at ten years in 53.0% after root repair, 99.3% after meniscectomy and 95.1% with nonoperative management. Those are simulation outputs rather than observed patients, and they inherit every weakness of what went into them.

The comparison nobody has run

Every number above comes from pooled cohorts and case series. Repair against resection has never been randomised, in any tear pattern.

That matters more here than it usually does, because the selection is not random in a knee-shaped way. Surgeons repair peripheral vertical tears in younger, more active patients with better cartilage, and resect degenerative flaps in older knees that are already changing. Both arms of every comparison above were chosen, and the difference between the arms includes the difference between the people in them. The signature of that problem is visible in the results: the structural gaps are large and the patient-reported gaps mostly are not, which fits a real chondroprotective effect and also fits repair being offered to better joints.

One boundary worth being explicit about. The case for preservation is built on traumatic tears. When a systematic review looked at repair of degenerative meniscal tissue, it did not do well — so "resect less" and "repair instead" are not the same recommendation, and the second one does not follow from the first.

What would settle it

A randomised trial of repair against resection in comparable tears is the missing study in this section, and everything on this page would change meaning if one existed. Two smaller gaps sit behind it: the pooled failure rate describes techniques older than the all-inside devices now in use, because five-year outcomes for those had not been reported when it was calculated; and the root-tear result with the widest structural gap is medial-only, so whether it carries to lateral roots is untested. In the meantime the honest summary is that preservation has the better mechanical argument, the better structural numbers, and the weaker study designs.