Cochrane in CORR: Arthroscopic Surgery for Degenerative Knee Disease (Osteoarthritis Including Degenerative Meniscal Tears)

Importance of the Topic Osteoarthritis (OA) of the knee is both common and a major contributor to disability. The symptoms of OA affect 10% of the worldwide population older than 60 years of age [18]. The incidence of degenerative meniscal tears increases with age and is strongly correlated with the presence of OA [3]. Although arthroscopic surgery, particularly arthroscopic debridement [8, 10], has been used to treat symptomatic degenerative meniscal tears, numerous studies have found it not to be superior to placebo surgery or nonsurgical treatments. A robust 2017 systematic review identified 13 randomized controlled trials and 12 observational studies that compared arthroscopy to placebo or nonoperative controls [4] and found no clinically important benefits of knee arthroscopy in terms of pain or function at 3 months or 2 years after surgery when compared to placebo or nonsurgical interventions. Despite the absence of clinical benefits to surgery in numerous studies, the number of patients undergoing knee arthroscopy and the average age of those patients have both increased [5]. Additionally, several orthopaedic professional and subspecialty societies continue to endorse the use of arthroscopic debridement for treating degenerative meniscal tears [1, 2, 17]. Because of the disconnect between those endorsements and the high-quality evidence from numerous randomized trials conducted around the world demonstrating arthroscopic surgery not to be beneficial for this indication when compared to safer, nonsurgical alternatives, debate in the orthopaedic community persists about how to treat degenerative meniscal tears and early osteoarthritis of the knee [6, 12, 13]. The current Cochrane review by O’Connor and colleagues updated the previously mentioned systematic review published in 2017 [4]. Synthesis of the available evidence is important to attempt to bridge the gap between knowledge and practice. In the current review [14], the authors analyzed 16 randomized control trials and trials that used quasi-randomized methods to determine the balance of risk and benefits associated with arthroscopic surgery for degenerative knee disease including OA and degenerative meniscal tears. The trials in this review compared patient-reported outcomes, including physical function, pain, return to activity, time to recovery, quality of life, treatment failure, and adverse events from patients who underwent arthroscopic surgery of the knee to placebo or nonoperative treatment. The review included 2105 patients. Overall, the authors found that arthroscopic surgery provides little or no benefit in pain, function, or knee-specific quality of life compared to placebo procedures and nonsurgical approaches like exercise programs and injection. Upon Closer Inspection The work by O’Connor and colleagues [14] is an up-to-date, robust review that included participants and interventions that largely reflect clinical practice. Control groups included placebo (four studies), exercise programs (eight studies), NSAIDs (one study), non-arthroscopic lavage (one study), glucocorticoid injection (one study), and hyaluronic acid (one study). Additionally, the studies in the review represented a diverse global population with varying levels of OA with and without meniscal tears. The follow-up for the studies demonstrated no difference in the short and longer term, with many studies having follow-up for 2 or more years. The review found that arthroscopic surgery provides little or no benefit in pain and function compared to placebo procedures (high certainty), exercise programs (moderate certainty), NSAIDs (low certainty), injections (low certainty), and nonarthroscopic lavage (low certainty). Though the participants included were diverse, the review excluded patients with acute traumatic knee pain. Additionally, six of the included studies excluded patients with locking or locked knees. Though these patients are rare in the degenerative population, critics of the available evidence have previously argued that this subgroup of patients may be more likely to benefit from surgical intervention. It should be noted, however, that thus far, subgroup analysis has failed to identify benefits in such groups [15, 16], and so any such claims must be considered speculative and unsupported by high-quality evidence. Post hoc analysis in a randomized controlled trial comparing arthroscopy to placebo demonstrated no difference in any of the primary or secondary outcome measures for patients with mechanical symptoms or unstable tears [16]; that is, no greater improvement was observed from surgery in patients with mechanical symptoms or unstable tears. Additionally, a 2020 study examined patient preoperative clinical factors proposed to be important in the success of meniscal surgery (including mechanical symptoms and traumatic tears) and found them to poorly predict changes in patient-reported outcomes 1 year postsurgery [15]. Treatment crossover was also present, which may underestimate the effectiveness of surgery. Conversely, though, patients who crossover to surgical groups in this setting are likely to be motivated and especially likely to gain benefit from the placebo effect, which appears rather substantial in this setting. Several included studies had patient crossover from nonoperative or placebo to surgery [7, 9, 11]. One study [9] demonstrated 30% crossover from the nonoperative to arthroscopic group. Patients who have persistent symptoms despite nonoperative management and crossed into the surgical arm in this trial had improvement of their symptoms after knee arthroscopy [9]. This study, however, was unblinded and thus may have increased the likelihood that patients would request operative intervention for their persistent symptoms. The rate of crossover in a large, blinded randomized controlled trial was lower (9%) [16], and that study found those who did cross over had no additional benefit from the arthroscopic procedure. Blinding in any future studies should be ensured to minimize bias and decrease patient crossover. Take-home Messages O’Connor and colleagues [14] confirm what has been previously demonstrated—that arthroscopic surgery shows little to no benefit over placebo and nonoperative interventions (including exercise programs and injection) in patients with degenerative changes in the knee. The review included patients with knee OA (with and without meniscal tears) and with degenerative meniscal tears alone. This review adds to the growing body of evidence demonstrating that surgical intervention is ineffective in this condition. It is important to have a frank discussion with patients regarding the natural course of knee OA and degenerative meniscal tears. Thorough counseling is necessary to ensure patients understand that abundant evidence demonstrates this procedure has shown no clinically important benefit over placebo and conservative treatments. Nonoperative interventions and lifestyle modification should be considered first-line treatment in the degenerative knee. Surgeons who continue to support the use of arthroscopic surgery in this patient population have a responsibility to conduct trials to provide evidence that identifies subgroups in which it may be beneficial.