Utility of Arthroscopic Surgery for Osteoarthritis of the Knee

Abstract

Currently, there is no consensus as to which patients would benefit most from arthroscopic surgery of the knee. Recently published randomized trials have shown limited efficacy for arthroscopic debridement and partial meniscectomy in patients with knee osteoarthritis. However, these clinical trials and others are limited by methodological problems. Indeed, many surgeons believe that arthroscopic surgery is indicated in a select group of patients, namely those with mild osteoarthritis and associated meniscal injury. More level I evidence will be required to better define the role of arthroscopic surgery in patients with osteoarthritis of the knee.

Introduction

Osteoarthritis of the knee is a leading cause of disability in the geriatric population. When medical management fails to provide symptomatic relief, a variety of arthroscopic procedures are considered, including lavage, debridement, partial meniscectomy, and abrasion arthroplasty. ^{1 -4} Although arthroscopic surgery has become a commonly performed procedure for degenerative knee arthritis, there is ongoing debate regarding its use as a treatment modality for osteoarthritis. Currently, there is no consensus as to which patients would benefit most from these procedures. Previous studies have yielded conflicting findings about the efficacy of arthroscopy, with some authors ^{1,4 -7} reporting satisfactory results and others ^3,8 arguing that it may be overutilized or it may contribute to unnecessary delays of total knee arthroplasty. The majority of these studies have relied on retrospective reviews of patient records, which carry the potential for bias inherent in such analyses. ⁹

Several recent randomized controlled studies have suggested limited clinical value for arthroscopic debridement ^10,11 and partial meniscectomy ^12,13 in patients with knee osteoarthritis. Sihvonen et al ¹² recently published a randomized, multicenter, double-blind trial in Finnish patients and reported no differences in outcomes between arthroscopic partial meniscectomy and a sham surgical procedure, a finding consistent with prior reports.^2.10,11,13 However, these clinical trials and others ^10,11 are limited by methodological problems and have raised concern regarding their interpretation among leading authorities. ^14,15 The aim of this review is to evaluate the current literature to better clarify the role of arthroscopic surgery for knee osteoarthritis in the elderly patients.

Current Evidence

Several earlier studies have sought to identify which subset of patients would benefit the most from arthroscopic surgery. The results of these studies suggest that arthroscopy is appropriate when performed in the earlier stages of the degenerative process. Aaron et al ¹⁶ conducted a cross-sectional study of 110 patients who underwent arthroscopic debridement for treatment of knee osteoarthritis. The authors found that good clinical outcomes were significantly correlated with mild arthritis (Kellgren-Lawrence grade 2), normal limb alignment, and a joint space width of ≥3 mm (P < .001). Conversely, patients with severe arthritis (Kellgren-Lawrence grade 4), limb malalignment, and a joint space width of <2 mm fared poorly. These findings are in agreement with previous studies ⁴ that identified a more normal mechanical axis and fewer prior surgeries to be strongly associated with better outcomes (P < .0001). Jackson et al ¹ performed a retrospective review of 121 patients at 4- to 6-year follow-up treated with arthroscopic lavage and debridement. Patients with earlier stages of degeneration (stages I, II, and III) had good to excellent results (77%-100%), while the majority of those with more advanced disease (stage IV) assessed their result as poor or fair, with 29% eventually requiring arthroplasty.

Arthroscopic surgery is believed to be especially beneficial in the treatment of the arthritic knee when there is associated meniscal damage. In the prospective study by Dervin et al, ¹⁷ the authors identified 3 clinical variables that were significantly associated with improvement after arthroscopic debridement, medial joint-line tenderness (P = .04), a positive Steinman test (P = .01), and the presence of an unstable meniscal tear (P = .01), all of which represent meniscal pathology. Figueroa et al ⁶ reported a higher percentage of good and excellent results with arthroscopic debridement in patients who had associated meniscal and cartilage injuries (76% and 84.6%, respectively). Katz et al ² reported on 351 patients with evidence of a meniscal tear and mild to moderate osteoarthritis on imaging who were assigned to either arthroscopic partial meniscectomy or physical therapy alone. Although both groups gained similar improvements in functional status and knee pain at 6 months, 30% of patients in the physical therapy arm eventually crossed over to surgery within the first 6 months.

In contrast to these earlier studies, there is now a growing body of randomized trials that calls into question the clinical efficacy of arthroscopic surgery for osteoarthritis of the knee. Moseley et al ¹⁰ broke new ground by publishing the first randomized controlled trial comparing arthroscopic debridement and arthroscopic lavage with placebo surgery in 180 patients with knee osteoarthritis. The primary end point was knee pain at 24 months after the intervention, as assessed by a 12-item self-reported knee-specific pain scale. Neither the debridement nor the lavage groups outperformed the placebo group at 12 or 24 months (P > .05). This led to the suggestion that a placebo effect may be at least partly responsible for the benefit seen with arthroscopic treatment. These findings were corroborated by Kirkley et al ¹¹ who randomized 178 patients with moderate to severe knee osteoarthritis to either arthroscopic surgery with physical and medical therapy or to treatment with physical and medical therapy alone. After 2 years, no significant differences were observed in Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) scores (P = .22). Similar results have been described for arthroscopic partial meniscectomy in at least 3 independent prospective randomized trials. ^2,12,13 In the most recent study by Sihvonen et al, ¹² 146 patients with knee symptoms but without radiographic evidence of osteoarthritis were randomized to either arthroscopic partial meniscectomy or sham surgery, which included a diagnostic arthroscopy with joint irrigation and lavage. Both groups demonstrated improvement in the Lysholm score, the Western Ontario Meniscal Evaluation Tool score, and visual analog pain scores after exercise at 1 year after intervention; however, no significant differences were noted between the groups. The authors concluded that arthroscopic partial meniscectomy provided no lasting benefit in patients with meniscal damage

Although these studies represent the small body of level I evidence in the literature, there are key limitations with each trial that merit critical evaluation. One of the concerns raised in the study by Moseley et al ¹⁰ was its use of a nonvalidated tool (the Knee-Specific Pain Scale) for assessing osteoarthritis outcomes. Moreover, the patients who initially met inclusion criteria were not universally included as some 44% declined to participate. Those who were included in the trial had more severe arthritis than those who declined participation (P < .001), creating an opportunity for selection bias and rendering the results subject to the effect of disease severity on outcomes exhibited in other lower level studies. Kirkley et al ¹¹ addressed some of these issues by measuring primary outcomes with the WOMAC score, a validated instrument for knee osteoarthritis that is cited extensively in the literature. ^2,17 Kirkley et al ¹¹ excluded patients with significant meniscal tears from their study. In fact, Marx ¹⁸ notes in his editorial that patients with findings of both meniscal injury and mild osteoarthritis stand to benefit the most from arthroscopic surgery. Although Sihvonen et al ¹² did include patients with tears of the medial meniscus, those with lateral meniscal tears, traumatic meniscal tears, or mechanical symptoms were excluded from their study. Furthermore, several authors ^14,15 have noted that the study population of 205 participants was small compared with the number that would be expected given their normal surgical volume. The authors’ use of a diagnostic arthroscopy with lavage as a sham surgery has also come under scrutiny, as this procedure may have contributed to the positive results seen in the placebo arm by diluting or removing inflammatory mediators known to exacerbate the natural history of knee osteoarthritis. ^14,15

Conclusion

The utility of arthroscopic surgery for osteoarthritis of the knee continues to be a topic of vigorous debate. Although recently published randomized trials have cast doubt on the value of arthroscopic procedures for knee osteoarthritis, many surgeons believe that arthroscopic surgery is indicated in a select group of patients, namely those with mild osteoarthritis and associated meniscal injury. The authors of the recent randomized trials are to be commended for their contribution of level I evidence to the literature, and more studies of this caliber will be required to better define the role of arthroscopic surgery in patients with osteoarthritis of the knee.