This 2-year study compared arthroscopic partial meniscectomy (APM) – a common knee surgery for degenerative meniscus tears – to placebo surgery in 146 patients aged 35-65 without osteoarthritis. Both groups showed similar improvements in pain, knee function, and quality-of-life scores at 24 months, with no statistically significant differences in any outcomes. Importantly, even patients with mechanical symptoms (like catching/locking) or specific "unstable" tear patterns didn't benefit more from real surgery. These results challenge the common belief that surgery helps after failed conservative treatment.

Knee Surgery for Degenerative Meniscus Tears: No Better Than Placebo After 2 Years

Table of Contents

• Background/Introduction
• Study Methods
• Key Findings
• Subgroup Analyses
• Clinical Implications
• Limitations
• Recommendations
• Source Information

Background/Introduction

Arthroscopic partial meniscectomy (APM) is one of the most common orthopedic operations worldwide, especially among middle-aged and older adults with knee pain. Over 1 million such procedures are performed annually, with rates steadily increasing until recent years. Surgeons often recommend APM when conservative treatments like physical therapy fail or when patients report mechanical symptoms such as knee catching or locking.

However, multiple high-quality studies have questioned APM's effectiveness for degenerative tears (wear-and-tear damage rather than acute injuries). Recent analyses of randomized trials found no clear advantage over non-surgical approaches. Despite this evidence, many guidelines still suggest surgery if conservative treatment fails, partly because about one-third of non-surgical patients in earlier studies eventually crossed over to surgery and reported improvement.

This study aimed to settle the debate using the most rigorous method: a placebo-controlled trial. Researchers tested whether APM outperforms simulated surgery and investigated if specific patient subgroups (like those with mechanical symptoms or unstable tears) truly benefit. The Finnish Degenerative Meniscal Lesion Study (FIDELITY) trial provides definitive evidence about when – or if – this common procedure actually helps patients.

Study Methods

This multicenter trial enrolled 146 adults aged 35-65 across five Finnish hospitals between 2007-2014. Participants had:

• Knee pain lasting >3 months consistent with medial meniscus tear
• MRI-confirmed degenerative tear
• No osteoarthritis (confirmed by X-ray and clinical exam)
• Failed conservative treatment (physical therapy, medications)

Key exclusions were traumatic tears (from major injuries like falls) or locked knees. After diagnostic arthroscopy confirming eligibility, patients were randomly assigned to either:

1. Real APM: Removal of damaged meniscus tissue
2. Placebo surgery: Incisions and instrument sounds without actual meniscus removal

Both groups received identical postoperative care and exercise programs. Crucially, patients, caregivers, and outcome assessors were blinded to treatment assignment. Participants could request real surgery after 6 months if symptoms persisted.

Researchers tracked outcomes for 24 months using:

• WOMET score (0-100 scale): Meniscus-specific quality-of-life measure
• Lysholm score (0-100): Knee function assessment
• Knee pain after exercise (0-10 scale)
• Patient satisfaction and return to normal activities
• Clinical exams for meniscus symptoms

The study had 90% power to detect clinically meaningful differences: 15.5-point change in WOMET, 11.5 in Lysholm, or 2.0 in pain scores. Statistical analyses included intention-to-treat assessment and subgroup analyses for patients with mechanical symptoms or unstable tear patterns.

Key Findings

At 24 months, both groups showed substantial improvement from baseline, but there were no statistically significant differences between real and placebo surgery in any primary outcome:

Primary Outcomes (Mean Change from Baseline)

• WOMET score:
  • APM group: +27.3 points (95% CI: 22.1 to 32.4)
  • Placebo group: +31.6 points (95% CI: 26.9 to 36.3)
  • Difference: -4.3 points (95% CI: -11.3 to 2.6; p=NS)
• Lysholm knee score:
  • APM: +23.1 points (95% CI: 18.8 to 27.4)
  • Placebo: +26.3 points (95% CI: 22.6 to 30.0)
  • Difference: -3.2 points (95% CI: -8.9 to 2.4; p=NS)
• Pain after exercise:
  • APM: -3.5 points (95% CI: -4.2 to -2.8)
  • Placebo: -3.9 points (95% CI: -4.6 to -3.3)
  • Difference: +0.4 points (95% CI: -0.5 to 1.3; p=NS)

Secondary Outcomes

No significant differences emerged in any secondary measures:

• Satisfaction rates: 77.1% APM vs 78.4% placebo (p=1.000)
• Improvement rates: 87.1% APM vs 85.1% placebo (p=0.812)
• Unblinding due to ongoing symptoms: 7.1% APM vs 9.2% placebo (p=0.767)
• Reoperations: 5.7% APM vs 9.2% placebo (p=0.537)
• Return to normal activities: 72.5% APM vs 78.4% placebo (p=0.442)
• Positive meniscus tests at clinical exam: Equal between groups

One serious adverse event (knee infection) occurred in the APM group. All outcomes remained statistically indistinguishable after adjusting for baseline scores and other factors.

Subgroup Analyses

Researchers specifically tested whether certain patient characteristics predicted better surgical outcomes:

Patients with Mechanical Symptoms (Catching/Locking)

46% of participants reported mechanical symptoms preoperatively. At 24 months:

• No difference in WOMET, Lysholm, or pain scores between APM and placebo groups
• p-value for interaction: 0.87 (WOMET), 0.25 (Lysholm), 0.32 (pain)

Patients with Unstable Tears

49% of APM and 54% of placebo patients had unstable tears (bucket-handle, flap, or longitudinal patterns). Results showed:

• Identical outcomes between surgery and placebo groups
• p-value for interaction: 0.49 (WOMET), 0.64 (Lysholm), 0.61 (pain)

The data conclusively showed no subgroup benefited more from real surgery. Even patients who had failed conservative treatment before enrollment did equally well with placebo.

Clinical Implications

These findings have profound implications for clinical practice:

• The improvement after APM appears largely attributable to placebo effects, given identical outcomes with simulated surgery
• Common clinical justifications for surgery – mechanical symptoms, specific tear patterns, or failed conservative treatment – lacked scientific support in this rigorous trial
• The high satisfaction rates (77-78%) and improvement rates (85-87%) in both groups suggest natural history and contextual effects drive recovery more than tissue removal

For patients, this means that opting for conservative management first doesn't risk missing a surgical "window of opportunity." The data challenge the notion that delaying surgery compromises outcomes. With no demonstrable benefit over placebo at 2 years, APM's role in degenerative tears needs fundamental reconsideration.

Limitations

While definitive, this study had important boundaries:

• Excluded traumatic tears: Findings apply only to degenerative tears without major injuries
• No advanced osteoarthritis: Results can't be generalized to patients with significant joint damage
• 24-month timeframe: Longer-term outcomes (5+ years) remain unknown
• Placebo surgery risks: Though minimal, placebo procedures carried anesthesia/surgical risks
• Non-participants differed: Eligible patients who declined participation had greater WOMET improvements after surgery, suggesting possible selection bias

Critically, this trial doesn't address whether surgery might help the small subgroup with true knee locking (only 2% of screened patients). The findings specifically challenge APM's value for the "catching" sensations and intermittent symptoms most patients experience.

Recommendations

Based on this evidence, patients with degenerative meniscus tears should:

1. Exhaust conservative treatments first: Prioritize physical therapy and pain management for at least 3-6 months
2. Question surgery for mechanical symptoms alone: "Catching" sensations don't predict better surgical outcomes
3. Seek second opinions if surgery is recommended for stable tears without trauma
4. Discuss placebo effects with providers: Understand that perceived surgery benefits may not come from meniscus removal
5. Consider clinical trials for new non-surgical approaches being developed in light of these findings

Healthcare systems should reconsider insurance coverage for APM in degenerative tears without clear mechanical locking. Resources might be better directed toward developing enhanced rehabilitation protocols and patient education about the natural history of meniscus tears.

Source Information

Original Article 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
Publication Date: 2018;77:188-195
DOI: 10.1136/annrheumdis-2017-211172

This patient-friendly article is based on peer-reviewed research. It preserves all original data while translating medical terminology for educational purposes.