The METEOR trial: No rush to repair a torn meniscus

Many patients who have osteoarthritis of the knee and a torn meniscus can defer having the meniscus repaired and undergo physical therapy instead. If a trial of physical therapy does not help, they can opt for surgery later.

This seems to be the take-home message from the recent Meniscal Tear in Osteoarthritis Research (METEOR) trial,¹ which compared the efficacy of arthroscopic partial meniscectomy plus physical therapy vs physical therapy alone for patients with knee symptoms, a meniscal tear, and mild to moderate osteoarthritis of the knee.¹

In brief, patients improved to a roughly similar degree with either approach, and although many patients assigned to physical therapy eventually underwent surgery anyway by 6 months, the delay did not adversely affect outcomes.

In this article, we review the background, design, and findings of the METEOR trial, and their implications for clinical practice.

SURGERY: HIGH VOLUME, BUT LITTLE EVIDENCE

Magnetic resonance imaging (MRI) often incidentally reveals meniscal lesions in middle-aged and older patients who have osteoarthritis and knee pain.² Should these patients undergo arthroscopic meniscal repair? The decision is difficult, since it is hard to distinguish the symptoms of a meniscal tear from those of osteoarthritis.³

Current evidence suggests that, for symptomatic knee osteoarthritis by itself, arthroscopic surgery is no more effective than conservative management.^4,5 But what about surgery for a torn meniscus in addition to osteoarthritis?

Osteoarthritis is the most common joint disease, accounting for many physician visits.⁶ More than 26 million Americans over age 25 have some form of it, and the prevalence of symptomatic, radiographically confirmed osteoarthritis of the knee was 12.1% in the third National Health and Nutrition Examination Survey.⁷

We used to consider osteoarthritis a “wear-and-tear” disease—thus the term “degenerative joint disease.” But today, we know that it is an active response to injury, involving inflammatory and metabolic pathways.⁸ Moreover, the risk of osteoarthritis and its progression seems to be higher in those who have had meniscal injury and total or arthroscopic partial meniscectomy.^9,10

MRI is not commonly used in managing knee osteoarthritis, but it has been used diagnostically in patients with symptoms of a meniscal tear, such as clicking, locking, popping, giving way, and pain with pivoting or twisting. Traumatic meniscal tears (a longitudinal or radial tear pattern) most often occur in active younger people and often lead to meniscal surgery.^11,12 In contrast, degenerative meniscal tears (horizontal, oblique, or complex tear pattern or meniscal maceration) tend to occur in older people,^11,12 but how to manage them is not widely agreed upon.

Of note, most patients with osteoarthritis of the knee have torn, macerated, or heavily damaged menisci.^13,14 Meniscal lesions are also common in middle-aged people in the general population, with a higher prevalence in people who are older, heavier, or female, or who have a family history of osteoarthritis.¹⁵

These abnormalities are only weakly associated with symptoms.² However, when a patient has knee symptoms and a torn meniscus is detected on MRI, the tear is often assumed to be the source of the symptoms, and meniscal tears are the most common reason for arthroscopy.¹⁶

Since we have no way to prevent the progression of joint damage from osteoarthritis with drugs or by any other means, the goal is to alleviate the symptoms. Many patients report pain relief or functional improvement after arthroscopic surgery. But arthroscopic lavage or debridement for osteoarthritis has not been found to be better than conservative treatment or placebo in randomized controlled trials.^4,5

In contrast, the current standard treatment for a symptomatic degenerative meniscal tear is arthroscopic partial meniscectomy. Nearly 500,000 of these procedures are performed annually in the United States.¹⁶ But based on the best evidence, arthroscopic partial meniscectomy does not result in better pain relief and functional improvement than does physical therapy alone in patients who have a torn meniscus and knee osteoarthritis.^17,18

OVERVIEW OF THE METEOR TRIAL

The METEOR trial was a randomized controlled trial conducted at seven US tertiary referral centers. Its aim was to compare the short-term (6-month) and long-term (12-month) efficacy of arthroscopic partial meniscectomy and physical therapy in patients with symptomatic meniscal tear and osteoarthritis of the knee.¹⁹ It was supported by the National Institute of Arthritis and Musculoskeletal and Skin Diseases.¹

Patients were age 45 and older

METEOR patients had to be at least 45 years old and have symptomatic meniscal tears and knee osteoarthritis detected on MRI or radiography.¹

Osteoarthritis was defined broadly, given that it begins well before the appearance of radiographic evidence such as an osteophyte or joint-space narrowing.¹⁹ Patients with cartilage defects on MRI were also enrolled, as were patients with radiographically documented osteoarthritis.¹⁹

Patients were considered to have a symptomatic meniscal tear if they had had at least 4 weeks of symptoms (such as episodic pain and pain that was acute and localized to one spot on the knee, as well as typical mechanical pain suggesting a meniscal tear, such as clicking, catching, popping, giving way, or pain with pivoting or twisting) in addition to evidence of a meniscal tear on MRI.¹⁹

Patients were excluded if they had a chronically locked knee (a clear-cut indication for arthroscopic partial meniscectomy), advanced osteoarthritis (Kellgren-Lawrence grade 4), inflammatory arthritis, clinically symptomatic chondrocalcinosis, or bilateral symptomatic meniscal tears.¹⁹ Patients who had undergone surgery or injection of a viscosupplement in the index knee during the past 4 weeks were also excluded.¹⁹

Of 1,330 eligible patients, 351 (26.4%) were enrolled and randomly assigned in a 1:1 ratio to a treatment group by means of a secure program on the trial website.^1,19 Of those who were eligible but did not enroll, 195 (14.6%) were not referred and 784 (58.9%) declined to participate. Of those who declined, more preferred surgery than physical therapy (36.1% vs 21%). No information is available on any differences in baseline characteristics between the enrolled patients and the eligible patients who declined.

Randomization was done in blocks of varying size within each site, stratified according to sex and the extent of osteoarthritis on baseline radiography. The extent of osteoarthritis was categorized either as Kellgren-Lawrence grade 0 (normal, no features of osteoarthritis) to grade 2 (definite osteoarthritis, a definite osteophyte without joint-space narrowing) or as Kellgren-Lawrence grade 3 (moderate osteoarthritis, < 50% joint-space narrowing).^1,19 The two treatment groups were similar with respect to age, sex, race or ethnicity, baseline Kellgren-Lawrence grade, and baseline Western Ontario and McMaster Universities Arthritis Index (WOMAC) physical function score.¹

The mean age of the participants was 58, and 85% were white. Sixty-three percent had Kellgren-Lawrence grade 0 to 2 osteoarthritis, and 27% had grade 3.¹

Surgery plus physical therapy vs physical therapy alone

The surgery group underwent arthroscopic partial meniscectomy, which involved trimming the damaged meniscus back to a stable rim^1,19 and trimming loose fragments of cartilage and bone.

After the procedure, patients were scheduled for physical therapy. Although there is no consensus on the need for or the effectiveness of postoperative physical therapy in this setting, the investigators believed that including it in both study groups would help to isolate the independent effects of surgery. The physical therapy regimen after surgery was similar to that provided in the nonoperative group.^1,19

Physical therapy was designed to address inflammation, range of motion, muscle strength, muscle-length restriction, functional mobility, and proprioception and balance.^1,19 There were three stages; criteria for advancing from one phase to the next included the level of self-reported pain, observed strength, range of knee motion, knee effusion, and functional mobility.^1,18

The duration of participation varied depending on the pace of improvement. Generally, the program lasted about 6 weeks.^1,19

Crossover and other therapies were allowed

Crossover from physical therapy alone to surgery was allowed during the trial if the patient and surgeon thought it was clinically indicated.

Participants in both groups were permitted to take acetaminophen and nonsteroidal anti-inflammatory drugs as needed. Intra-articular injections of glucocorticoids were also allowed during the trial.