After 2 years of follow-up, arthroscopic partial meniscectomy (APM) was no better than sham surgery for patients with degenerative medial meniscal tears and no evidence of knee osteoarthritis, reported Finnish researchers in Annals of the Rheumatic Diseases.

Comparing partial meniscectomy and sham-surgery patients, Teppo LN Jarvinen, MD, PhD, of the University of Helsinki, and colleagues found no significant between-group differences 24 months after surgery:

• In Western Ontario Meniscal Evaluation Tool (WOMET) scores, the mean change from baseline was 27.3 in the APM group and 31.6 in the sham-surgery group (between-group difference, -4.3; 95% CI -11.3 to 2.6)
• In Lysholm knee scores, the mean change was 23.1 from baseline in the APM group and 26.3 in the sham group (between-group difference, -3.2; 95% CI -8.9 to 2.4)
• In knee pain after exercise, the mean change from baseline was 3.5 for APM patients and 3.9 for sham patients (between-group difference, -0.4; 95% CI -1.3 to 0.5)

“These results support the evolving consensus that degenerative meniscus tear represents an (early) sign of knee osteoarthritis, rather than a clinical entity on its own,” the authors wrote. “Accordingly, caution should be exercised in referring patients with knee pain and suspicion of a degenerative meniscal tear to MRI examination or APM, even after a failed attempt at conservative treatment.”

This research was an extension of the Finnish Degenerative Meniscal Lesion Study (FIDELITY), a multicenter, randomized, double-blind trial that studied the efficacy of a partial meniscectomy in patients who had a degenerative tear of the medial meniscus, but no clinical or radiographic evidence of knee arthritis.

In FIDELITY, which took place in five orthopedic centers in Finland from December 2007 to March 2014, 146 patients ages 35 to 65 years old were randomly assigned to receive either a partial meniscectomy (70 participants) or sham surgery (76 participants). Baseline characteristics of the two groups were similar. All patients had a suspected meniscus tear that was verified later by MRI and knee arthroscopy. The researchers excluded patients whose symptoms were induced by obvious trauma or who had a recent history of locked knee.

Patients first underwent diagnostic knee arthroscopy, and during the same operation, had either APM or sham surgery. During the APM, surgeons removed the damaged and loose parts of the meniscus until they reached solid meniscal tissue, preserving as much of the meniscus as possible. During the sham procedure, surgeons simulated a partial meniscectomy and mimicked the sounds and sensations of a true APM. Both groups received post-operative care according to the same protocol. At 24 months, an independent orthopedic surgeon, who did not know how treatment had been allocated, evaluated all patients.

Primary outcome targets for the current wave of the study were the changes in WOMET, Lysholm knee score and pain after exercise from baseline to 24 months after surgery. WOMET and Lysholm scores each ranged from 0 to 100, with 0 indicating the most severe symptoms and 100 the absence of symptoms. Knee pain was assessed on a scale of 0 to 10, with 0 representing no pain and 10 extreme pain.

Across all primary outcomes, both groups showed a marked improvement, but differences between the two groups did not reach statistical significance. There was no between-group difference in the frequency of patients returning to normal activity level, and no statistically significant difference in meniscal tests upon clinical examination.

The researchers also studied two subgroups — individuals with mechanical symptoms of the knee and individuals with unstable meniscus tear — and found no differences in outcomes between partial meniscectomy and sham-surgery patients.

In an interview with MedPage Today, Michael Sparks, MD, an orthopedic surgeon at Dartmouth-Hitchcock Medical Center in Lebanon, New Hampshire, noted that this study helps dispel the idea that any mechanical symptom can be fixed by surgery. “In my practice, I’ve been talking about that with patients for some time,” he said.

One thing this research is missing, Sparks observed, is a third group — specifically, one that had no treatment at all. “Both groups in this study had a perceived intervention, and that makes it hard to have a complete evaluation of the treatment,” he said.

Limitations of the study included the type of patients chosen, a concern voiced when the initial trial results were published since the terms “degenerative” and “traumatic” meniscal injuries can be vague. The authors clarified in this report that patients with sudden injuries related to voluntary muscle activities (such as kneeling, bending, or kicking) or with a minor knee twist were included, but those who fell from a chair, stairs, or a bicycle or who slipped on ice were not.

The generalizability of the FIDELITY data also was questioned when the findings first were publicized, but the researchers maintained they specifically recruited patients with a medial meniscus tear and no OA because these individuals potentially could have an “optimal response” to APM.

The authors also noted that their study may be limited since patients with a true locked knee (who were unable to extend their knee fully) were excluded, thus some caution may be warranted when interpreting their findings.

• Reviewed by F. Perry Wilson, MD, MSCEAssistant Professor, Section of Nephrology, Yale School of Medicine and Dorothy Caputo, MA, BSN, RN, Nurse Planner