Does Surgery Help Degenerative Meniscus Tears? 2-Year Study Compares Arthroscopy to Placebo

Table of Contents

• Key Findings at a Glance
• Background: Understanding Meniscus Tears
• Study Methods: How the Research Was Conducted
• Detailed Results: What the Study Discovered
• Clinical Implications: What This Means for Patients
• Study Limitations
• Patient Recommendations
• Source Information

In a 2-year study of 146 adults aged 35-65 with degenerative meniscus tears and no knee osteoarthritis, researchers found no significant difference in outcomes between those receiving actual arthroscopic partial meniscectomy (APM) surgery and placebo surgery. Both groups showed similar improvements in pain relief, knee function, and satisfaction rates, with WOMET scores improving by 27.3 points in the surgery group versus 31.6 in the placebo group. The study also found no evidence that patients with mechanical symptoms (like knee catching) or specific tear types benefited more from surgery. These results challenge common assumptions about surgical benefits for this condition.

Background: Understanding Meniscus Tears

Arthroscopic partial meniscectomy (APM) ranks among the most common orthopedic operations worldwide, particularly for middle-aged and older patients experiencing knee pain from degenerative tears. These tears often develop gradually without major injuries and can cause persistent discomfort. Historically, APM usage surged from the 1990s through the 2010s despite growing evidence questioning its effectiveness compared to non-surgical treatments.

Current medical guidelines typically recommend trying conservative approaches first—like physical therapy and pain management—before considering surgery. However, two arguments have supported APM use: some patients report improvement after surgery when conservative treatments fail, and certain subgroups (like those with "mechanical symptoms" or "unstable" tears) were thought to benefit more. Mechanical symptoms include sensations of catching or locking in the knee joint, while unstable tears refer to specific tear patterns that might cause more instability.

This study aimed to definitively test whether APM outperforms placebo surgery over a 24-month period. Crucially, it also examined whether those presumed "beneficial subgroups" actually experienced better surgical outcomes. The Finnish Degenerative Meniscal Lesion Study (FIDELITY) trial builds on earlier research and addresses a critical gap by including rigorous placebo controls to eliminate bias from patient expectations.

Study Methods: How the Research Was Conducted

Researchers conducted a multicenter, randomized, double-blind trial across five orthopedic centers in Finland between December 2007 and March 2014. The study included 146 adults aged 35-65 years who met specific criteria:

• Persistent knee symptoms lasting over 3 months
• MRI and clinical examination confirming degenerative medial meniscus tear
• No knee osteoarthritis (confirmed via X-ray using Kellgren-Lawrence grade 0-1)
• No history of major knee trauma or locked knee

Participants were randomly assigned to either actual APM surgery (70 patients) or placebo surgery (76 patients). The placebo procedure mimicked real surgery—complete with skin incisions, surgical sounds, and matching operating room time—but no meniscus tissue was removed. Both groups received identical postoperative care, including walking aids and home exercise programs.

Key outcomes measured over 24 months included:

• Primary measures:
  • WOMET score (meniscus-specific quality of life, 0-100 scale)
  • Lysholm knee score (knee function, 0-100 scale)
  • Knee pain after exercise (0-10 scale)
• Secondary measures: Patient satisfaction, treatment unblinding rates, return to normal activities, and clinical meniscus tests

Researchers also analyzed two subgroups: patients with mechanical symptoms (46% of participants) and those with unstable tear patterns (49-54% of participants). Statistical analysis focused on whether differences between groups exceeded established thresholds for clinical significance—15.5 points for WOMET, 11.5 for Lysholm, and 2.0 for pain scores.

Detailed Results: What the Study Discovered

At the 24-month follow-up (with only 2 participants lost to tracking), both surgery and placebo groups showed substantial improvement from baseline. However, no statistically significant differences emerged between actual surgery and placebo in any outcome measure:

Primary Outcomes

• WOMET scores improved 27.3 points in APM group vs. 31.6 in placebo group (difference: -4.3; 95% CI: -11.3 to 2.6)
• Lysholm scores improved 23.1 points in APM group vs. 26.3 in placebo group (difference: -3.2; 95% CI: -8.9 to 2.4)
• Pain after exercise decreased 3.5 points in APM group vs. 3.9 in placebo group (difference: -0.4; 95% CI: -1.3 to 0.5)

Adjusting for age, sex, and minor degenerative changes didn't alter these conclusions. Figure 2 in the original paper visually confirms overlapping improvement trajectories throughout the study period.

Secondary Outcomes

Rates of patient satisfaction and perceived improvement were nearly identical between groups:

• 77.1% satisfied with APM vs. 78.4% with placebo (p=1.000)
• 87.1% reported improvement with APM vs. 85.1% with placebo (p=0.812)
• Only 7.1% of APM patients requested unblinding due to ongoing symptoms vs. 9.2% of placebo patients (p=0.767)

Other notable findings:

• Reoperation rates: 5.7% (APM) vs. 9.2% (placebo)
• 1 serious adverse event (knee infection) occurred in the APM group
• No differences in return to normal activities (72.5% vs 78.4%) or positive meniscus tests during clinical exams

Subgroup Analyses

Contrary to common assumptions:

• Patients with mechanical symptoms (catching/locking) showed no additional benefit from APM
• Those with unstable tear patterns (longitudinal, bucket handle, or flap tears) also showed no advantage with surgery

Statistical tests for interaction confirmed no meaningful differences in outcomes for either subgroup (p>0.05 for all comparisons).

Clinical Implications: What This Means for Patients

This 2-year randomized trial provides strong evidence that arthroscopic partial meniscectomy offers no detectable advantage over placebo surgery for patients with degenerative meniscus tears and no osteoarthritis. The nearly identical outcomes in both groups suggest that perceived benefits of surgery may largely stem from placebo effects, natural healing, or exercise rehabilitation.

Notably, the study challenges two widely held beliefs about when surgery might help:

1. Mechanical symptoms (like knee catching or locking) didn't predict better surgical outcomes.
2. Unstable tear patterns (often considered more serious) showed no extra benefit from APM.

These findings align with recent guidelines discouraging APM as first-line treatment. They also help explain why patients who "fail" conservative treatment and later opt for surgery often report improvement—the act of undergoing any procedure appears equally effective as actual meniscus removal in this population.

Study Limitations

While robust, this trial had important constraints:

• It excluded patients with traumatic meniscus tears (e.g., from falls or sports injuries), so results apply only to degenerative tears.
• Follow-up was limited to 2 years; longer-term outcomes remain unknown.
• Participants were all Finnish, potentially limiting generalizability to other populations.
• 24 eligible patients declined randomization and underwent APM directly, though their outcomes appeared similar to trial participants.

The placebo surgery design—while scientifically rigorous—also raises ethical considerations about performing sham procedures. However, the minimal risk and high clinical value of the findings were deemed justifiable.

Patient Recommendations

Based on these results, patients with degenerative meniscus tears and no osteoarthritis should consider the following:

1. Prioritize non-surgical approaches: Exercise programs, physical therapy, and pain management should be the initial treatment strategy.
2. Question surgery for mechanical symptoms: Don't assume catching/locking sensations require immediate surgery—these symptoms didn't predict better outcomes in this study.
3. Understand placebo effects: Recognize that perceived surgical benefits may stem from natural healing or psychological factors rather than tissue removal.
4. Discuss alternatives: If considering APM after failed conservative treatment, ask your doctor about supervised exercise programs or other options.
5. Monitor long-term outcomes: While 2-year data shows no surgical advantage, continue regular check-ups to track knee health.

These recommendations align with current guidelines from major orthopedic associations while incorporating this trial's groundbreaking evidence about placebo effects.

Source Information

Original Research Title: Arthroscopic partial meniscectomy versus placebo surgery for a degenerative meniscus tear: a 2-year follow-up of the randomised controlled trial
Authors: Raine Sihvonen, Mika Paavola, Antti Malmivaara, Ari Itälä, Antti Joukainen, Heikki Nurmi, Juha Kalske, Anna Ikonen, Timo Järvelä, Tero AH Järvinen, Kari Kanto, Janne Karhunen, Jani Knifsund, Heikki Kröger, Tommi Kääriäinen, Janne Lehtinen, Jukka Nyrhinen, Juha Paloneva, Outi Päiväniemi, Marko Raivio, Janne Sahlman, Roope Sarvilinna, Sikri Tukiainen, Ville-Valtteri Välimäki, Ville Äärimaa, Pirjo Toivonen, Teppo LN Järvinen, the FIDELITY Investigators
Journal: Annals of the Rheumatic Diseases (2018;77:188-195)
DOI: 10.1136/annrheumdis-2017-211172
This patient-friendly article is based on peer-reviewed research and preserves all original data and findings.