Patient Characteristics No Help in Predicting Meniscal-Surgery Outcomes

By Scott Baltic

July 15, 2019

NEW YORK (Reuters Health) - Patient-reported outcomes one year after meniscal surgery can't be predicted with a model using as many as 18 preoperative factors, according to a new study.

The prospective cohort study "essentially quashes the existence of 'subgroups' with certain characteristics having a particularly favourable outcome after meniscal surgery," researchers write in the British Journal of Sports Medicine, online June 11.

Kenneth Pihl of the University of Southern Denmark, in Odense, and colleagues note that there is "widespread debate" over the use of arthroscopic partial meniscectomy (APM) and whether there are identifiable groups of patients who are likely to benefit from the procedure. They add that recent randomized trials have questioned APM's effectiveness for degenerative meniscal tears.

The study enrolled all patients in a cohort of individuals undergoing APM for a meniscal tear at any of four centers in southern Denmark. All patients were 18 or older and with suspicion of a meniscal tear, based on clinical examination, injury history, and MRI (if considered necessary).

Most of the patients (600 out of 641) received a resection of the meniscus. The 18 factors in the prognostic model included back problems, knee alignment, duration of meniscal tear symptoms, symptom onset and a variety of factors around knee-related symptoms, such as pain and catching/locking.

Patients improved on average 18.6 on the Knee injury and Osteoarthritis Outcome Score scale.

The strongest prognostic factors for improvement were no previous meniscal surgery on the index knee and more severe preoperative knee-related symptoms. But the model's overall predictive performance was judged to be low, with an apparent R-square of 0.162 and an optimism-adjusted R-square of 0.080.

The model also showed "poor" calibration, the team reports.

Pihl told Reuters Health in an email the subgroups of patients most often proposed as benefitting from meniscal surgery are: patients with mechanical symptoms, such as catching or locking of the knee, or an inability to straighten the knee fully; patients with a traumatic meniscal tear (often from a sports-related injury); and patients who are more physically active.

"The majority of middle-aged and older patients with degenerative meniscal tears with and without knee osteoarthritis should not undergo meniscal surgery," added Pihl, a PhD student.

Although it's possible that a small subgroup with specific tear types, such as a large bucket-handle tear resulting in a chronically locked knee, might benefit from surgery, he added, these tears are rare among middle-aged and older patients.

The picture is less clear in younger patients, Pihl continued, "but it seems that their perceived knee symptoms are more related to the meniscus than for older patients." He noted that two trials on younger patients are ongoing.

Dr. Reed Alexander Siemieniuk of the Department of Health Research Methods, Evidence and Impact, at McMaster University, in Hamilton, Canada, told Reuters Health by email, "There may be some people in whom the surgery does confer a substantial benefit, but this study adds to a growing body of literature suggesting that it may not be possible to identify a group of patients in whom the surgery is effective."

"From the first randomized trials of arthroscopic knee surgery that showed it isn't effective, proponents of surgery have argued that the trials enrolled the wrong patients and thus inferred that they can identify patients who benefit from surgery," he noted.

Despite the many patient subgroups in which proponents have suggested benefit, "Unfortunately, the evidence suggests that surgery isn't effective in any of these proposed subgroups," concluded Dr. Siemieniuk, who chaired a panel that wrote clinical practice guidelines regarding degenerative knee arthritis and meniscal tears, published in The BMJ in 2017.

He echoed Pihl's advice that almost no one should be offered arthroscopic partial meniscectomy for knee pain, adding, "The very few patients who cannot fully extend their knee because of a meniscal tear might benefit from partial meniscectomy."


Br J Sports Med 2019.