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The METEOR trial: No rush to repair a torn meniscus

Cleveland Clinic Journal of Medicine. 2014 April;81(4):226-232 | 10.3949/ccjm.81a.13075
April 1, 2014|Cleveland Clinic Journal of Medicine
Yong Gil Hwang, MD;C. Kent Kwoh, MD
Author and Disclosure Information

Yong Gil Hwang, MD
Assistant Professor of Medicine, Division of Rheumatology, Department of Medicine, University of Pittsburgh, PA

C. Kent Kwoh, MD
Professor of Medicine and Medical Imaging, The Charles A. L. and Suzanne M. Stephens Chair of Rheumatology; Chief, Division of Rheumatology; and Director, University of Arizona Arthritis Center, Department of Medicine, University of Arizona, Tucson; Member, Treatment Guidelines Committee, Osteoarthritis Research Society International

Address: C. Kent Kwoh, MD, The University of Arizona Arthritis Center, 1501 North Campbell Avenue, PO Box 245093, Tucson, AZ 85724-5093; e-mail: kwoh@arthritis.arizona.edu

ABSTRACTIt is uncertain whether arthroscopic partial meniscectomy is better than physical therapy in patients who have a symptomatic torn meniscus on top of osteoarthritis of the knee. The Meniscal Repair in Osteoarthritis Research (METEOR) trial concluded that physical therapy is acceptable at first, and that surgery is not routinely needed. In patients assigned to physical therapy who eventually needed surgery, the delay resulting from a trial of conservative management did not impair outcomes at 12 months from the initial presentation. Here, we analyze the background, design, findings, and clinical implications of the METEOR trial.

KEY POINTS

  • METEOR trial was a randomized controlled trial comparing the short-term and long-term efficacy of arthroscopic partial meniscectomy vs physical therapy in patients with a symptomatic meniscal tear and knee osteoarthritis.
  • Both treatment groups in the METEOR trial received physical therapy in order to determine the incremental benefit of surgery and physical therapy compared with physical therapy alone.
  • The trial investigators used specific definitions of osteoarthritis and symptoms of meniscal tear.
  • Meniscectomy is often performed for patients with symptoms consistent with a meniscal tear and evidence of a meniscal tear on magnetic resonance imaging, but the benefits of this procedure are unclear.

OUTCOMES MEASURED

WOMAC physical function score

The primary outcome of the METEOR trial was the difference between the study groups in the change in WOMAC physical function score from baseline to 6 months, at which point participants were expected to have achieved maximum improvement.1,19 Questionnaires were also administered at 3 months to assess the early response to surgery or physical therapy and again at 12 months.

The complete WOMAC also measures pain and stiffness in addition to physical function, with separate subscales for each. The change in WOMAC score is one of the most widely endorsed outcome measures in assessing interventions in osteoarthritis or other conditions of the lower extremities.20 The METEOR trial authors considered the WOMAC scale to be highly valid and reliable, with a Cronbach alpha value of 0.97 (maximum value = 1; the higher the better).

No ceiling or floor effects were observed in the WOMAC physical function score in patients with osteoarthritis and a meniscal tear in a pilot study for METEOR.19

In the main METEOR study, WOMAC physical function was scored on a scale of 0 to 100, with a higher score indicating worse physical function.1 Changes in the score were also measured as a yes-or-no question, defined a priori as whether the score declined by at least 8 points, which is considered the minimal clinically important difference in osteoarthritis patients.1,19

KOOS and MOS SF-36 scores

Secondary outcomes were measured in several domains, including pain, generic functional status, quality of life, and health care utilization.1,19

The KOOS (Knee Injury and OA Outcome Scale) is specific for knee pain, being designed to evaluate short-term and long-term symptoms and function in patients with knee injury and associated problems.21 It has five subscales, which are scored separately: pain, other symptoms, activities of daily living, sport and recreation, and knee-related quality of life.21 Since the WOMAC pain scale showed a ceiling effect in the pilot study in patients undergoing surgery, the authors chose the KOOS pain scale as a pain measure.19 Scores were transformed to a 0–100 scale, with a higher score indicating more pain.1

The MOS SF-36 (Medical Outcomes Study 36-item short form) was used to measure general health status and function.1,19

STATISTICAL ANALYSIS: INTENTION-TO-TREAT AND AS-TREATED

The study was powered to detect a 10-point difference in WOMAC physical function scores at 6 months of follow-up between the operative and nonoperative groups, anticipating losses to follow-up and crossover, with preplanned subgroup (Kellgren–Lawrence grade 0–2 vs grade 3) analysis.1,19

The primary analysis used a modified intention-to-treat approach and was implemented with an analysis of covariance with changes in the WOMAC score from baseline to 6 months as the dependent variable, treatment as the independent variable of interest, and study site as a covariate. Other covariates, such as age, sex, and baseline Kellgren-Lawrence grade, were balanced across groups and were therefore not included in the analysis.1,19

Secondary analyses used an “as-treated” approach, ie, according to the treatment actually received.1,19 Secondary intention-to-treat analysis—using binary outcome measures in which treatment failure was defined as improvement in the WOMAC score of less than 8 points or crossing over to the other treatment—was also performed to estimate efficacy at the level of the patient rather than at the group level.1,19

BOTH GROUPS IMPROVED

In the intention-to-treat analyses at 6 months and 12 months after randomization, both groups improved, with no clinically important or statistically significant differences between the groups in functional status (WOMAC score, MOS SF-36 score) or pain (KOOS score).1 The mean improvement (decline) in the WOMAC score from baseline to 6 months was 20.9 points in the surgery group vs 18.5 points in the physical therapy group, a difference of 2.4 points (95% confidence interval [CI], −1.8 to 6.5).1

35% of physical therapy patients underwent surgery by 12 months

Of the 177 patients randomized to physical therapy alone, by 6 months 1 had died, 1 had undergone total knee replacement, 4 had withdrawn, and 2 were lost to follow-up. Of the 169 remaining, 51 (30%) had undergone arthroscopic partial meniscectomy. An additional 8 patients who were assigned to physical therapy crossed over to surgery between 6 and 12 months.1,19

Of the 174 patients randomized to surgery, by 6 months 1 had died, 3 had undergone total knee replacement, 7 had withdrawn, and 2 were ineligible. Of the 161 remaining, 9 (6%) had not undergone the procedure.

Other outcomes

Subgroup analysis based on the baseline radiographic grade (Kellgren-Lawrence grade 0 to 2 vs grade 3) did not show a difference between groups in functional improvement at 6 months (P = .13 for interaction).1

No statistically significant difference was noted in rates of overall or specific adverse events between the two groups over the first 12 months.1 Adverse events rated as mild or moderate in severity occurred in 15 participants in the surgery group and 13 participants in the physical therapy group.1 Long-term risks associated with these interventions are being assessed, and longitudinal assessment of imaging studies is planned to address this question but is not yet available.1,18

In the physical therapy group, 21 patients (12%) received intra-articular glucocorticoid injections, as did 9 patients (6%) in the surgery group.1,19

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