Arthroscopy or Therapy for the Degenerative Meniscal Tear
A degenerative meniscal tear in a middle-aged knee usually improves as much with exercise therapy as with surgery, and an unneeded meniscectomy adds operative risk and may speed arthritis.
Key terminology
- Medial meniscus
- This C-shaped cartilage pad sits between the inner femoral condyle and the tibial plateau. It spreads load across the knee and is the meniscus most often torn by wear.
- Degenerative meniscal tear
- This tear comes from gradual wear in a middle-aged knee, often with no clear injury. It often sits alongside early arthritis.
- Arthroscopic partial meniscectomy (APM)
- This arthroscopic surgery trims away the torn part of the meniscus and leaves the rest. It is one of the most common orthopedic operations.
- Noninferiority margin
- This trial asks whether a new option is no worse than a standard one by more than a set amount. That amount is the noninferiority margin.
- Sham surgery
- This control arm receives skin incisions and a simulated operation with nothing repaired or removed. It separates the effect of the procedure from the placebo effect of having surgery.
- Mechanical symptoms
- These are catching, clicking or brief locking sensations that patients report in the knee. They are often blamed on a torn meniscus.
- True locked knee
- This knee cannot fully straighten because a displaced meniscal fragment blocks the joint. It is a mechanical block that therapy cannot fix.
Takeaways
- Exercise therapy is first-line for a degenerative meniscal tear in a knee that can fully extend. A randomized trial of 321 patients aged 45-70 with no locking compared APM with 16 sessions of physical therapy over 8 weeks. PT was noninferior over 24 months, with a difference of 3.6 points on a 100-point knee score against a noninferiority margin of 8. The gap was 3.5 points at 5 years (van de Graaf et al, JAMA 2018;320:1328-1337, PMID 30285177; Noorduyn et al, JAMA Netw Open 2022;5:e2220394, PMID 35802374).
- Arthroscopic partial meniscectomy did no better than sham surgery for a degenerative medial meniscus tear. In 146 patients aged 35-65 with no knee OA, both groups improved by similar amounts at 12 months, with no difference in any primary outcome. The result held at 2 years, including in patients with an unstable tear or mechanical symptoms (Sihvonen et al, N Engl J Med 2013;369:2515-2524, PMID 24369076; Sihvonen et al, Ann Rheum Dis 2018;77:188-195, PMID 28522452).
- A meniscal tear on MRI in a knee over 50 is often an incidental finding. In 991 adults aged 50-90, tear prevalence ranged from 19% in women 50-59 to 56% in men 70-90. Of those with a tear, 61% had no knee pain, aching or stiffness in the prior month. Standing knee films come first in a middle-aged knee, and MRI is typically not first-line (Englund et al, N Engl J Med 2008;359:1108-1115, PMID 18784100; Beaufils et al, Knee Surg Sports Traumatol Arthrosc 2017;25:335-346, PMID 28210788).
- Catching and occasional locking do not predict who benefits from meniscectomy. After surgery, catching or locking was reported by 49% after APM and 43% after sham. Among the 69 patients who had these mechanical symptoms before surgery, APM gave no added relief. A true locked knee that cannot fully extend was not studied and remains the accepted exception (Sihvonen et al, Ann Intern Med 2016;164:449-455, PMID 26856620; Siemieniuk et al, BMJ 2017;357:j1982, PMID 28490431).
- Starting with physical therapy keeps surgery available for the knee that does not improve. In 351 patients ≥45 y/o with a meniscal tear and mild to moderate OA, function improved 20.9 points with surgery and 18.5 with PT, a nonsignificant difference. 30% of the PT arm had crossed over to surgery by 6 months, and 29% had APM by 24 months in a second trial (Katz et al, N Engl J Med 2013;368:1675-1684, PMID 23506518; van de Graaf et al, JAMA 2018;320:1328-1337, PMID 30285177).
- Removing meniscus may speed knee arthritis. At 5 years the APM group had slightly more radiographic OA progression than sham (adjusted risk difference 13%, 95% CI -2% to 28%) with no better symptoms. In a matched study, all 31 knees with a partial meniscectomy in the prior year went on to radiographic OA. The observational data cannot separate the surgery from the tear that prompted it (Sihvonen et al, Br J Sports Med 2020;54:1332-1339, PMID 32855201; Roemer et al, Eur Radiol 2017;27:404-413, PMID 27121931).
- Guidelines agree surgery is not first-line and disagree on whether it has a role later. A 2017 BMJ guideline made a strong recommendation against arthroscopy in nearly all degenerative knee disease, with a true locked knee the only possible exception. ESSKA allows APM after about 3 months of failed nonoperative care. The BMJ panel listed AAOS as supportive of meniscectomy (Siemieniuk et al, BMJ 2017;357:j1982, PMID 28490431; Beaufils et al, Knee Surg Sports Traumatol Arthrosc 2017;25:335-346, PMID 28210788).
- One trial found less pain when arthroscopy was added to exercise, so the evidence is not unanimous. In 150 patients aged 45-64 with symptoms for more than 3 months, KOOS pain improved 10.6 points more with exercise plus arthroscopy at 12 months. A 2023 meta-analysis of 4 trials found no added benefit of APM over exercise for pain or function at 5 years (Gauffin et al, Osteoarthritis Cartilage 2014;22:1808-1816, PMID 25086401; Fernández-Matías et al, Arch Orthop Trauma Surg 2023;143:2609-2620, PMID 35996030).