Scoping for Knee OA Revisited: It's Still Not OK
Abstract & Commentary
By Allan J. Wilke, MD, Residency Program Director, Associate Professor of Family Medicine, University of Alabama at Birmingham School of Medicine Huntsville Regional Medical Campus, Huntsville. Dr. Wilke reports no financial relationship to this field of study.
Synopsis: In knee OA, arthroscopic surgery confers no benefit.
Source: Kirkley A, et al. A randomized trial of arthroscopic surgery for osteoarthritis of the knee. N Engl J Med 2008;359:1097-1107.
Six years ago, NEJM reported1 (and I reviewed2) Moseley's study of the use of arthroscopy to treat knee osteoarthritis (OA). The conclusion was that patients randomized to surgery did not experience reduced pain or improved function. After the study was published, several concerns were raised, namely, the study group was composed of elderly male veterans,3 X-rays during posterior-anterior flexion in a weight-bearing position were not performed,4 the pain scale was not validated, and the study was underpowered.5
Kirkley and colleagues from the University of Western Ontario report their trial that answers those concerns. Patients had to be at least 18 years old and without large meniscal tears. They screened 277 patients for eligibility, and after appropriate exclusion, they randomized 188. Reasons for exclusion included more than 5° of misalignment, inflammatory or postinfectious arthritis, previous arthroscopy, history of major knee trauma, severe OA, and corticosteroid knee injection in the last three months, among others. Subjects were X-rayed to grade the severity of OA, received a detailed physical examination of the knee, and completed several questionnaires and clinical scoring tools, including the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) and the Short Form-36 Physical Component Summary, both validated instruments.
Patients were randomized to the study group, which received optimized physical and medical therapy and arthroscopic treatment, or the control group which only received the physical and medical therapy. Arthroscopic therapy could involve synovectomy, debridement, or excision of meniscal degenerative tears, cartilage fragments, or chondral flaps and osteophytes. Physical therapy involved 1-hour weekly sessions for 12 weeks. Participants were also instructed in a home exercise program. Medical therapy began with acetaminophen and nonsteroidal anti-inflammatory drugs, and progressed to hyaluronic acid injection if necessary. Patients were also offered oral glucosamine. Patients were seen periodically by a nurse who was blind to treatment, and all patients wore a neoprene sleeve over their knees to hide the study groups' surgical scars. There were 94 patients assigned to surgery; two withdrew consent and six declined to undergo arthroscopy. The same number was assigned to the control group. Eight withdrew consent. The two groups were similar in all respects. They were in their late 50s and predominantly female, with a body mass index of 31 kg/m2.
At the 3-month check, the WOMAC scores in the surgery group showed greater improvement than the control group. After that and through two years of follow-up, there were no significant differences between the groups. Both groups showed improvement. The investigators performed subgroup analysis for patients who were having mechanical symptoms of catching or locking; again, there was no difference between the groups. When physical function, pain, or quality of life was compared, the groups were similar.
Commentary
Medicine has a shameful history of adopting new technology and medications without thorough testing. "First, do no harm" has been replaced by "We do it because we can." Marx, in his editorial,6 concludes "osteoarthritis of the knee (in the absence of a history and physical examination suggesting meniscal or other findings) is not an indication for arthroscopic surgery and indeed has been associated with inferior outcomes after arthroscopic knee surgery." Since patients in both groups improved with physical and medical therapy, that should be our mainstay of treatment, along with encouraging our patients to lose weight and to walk regularly.
By the way, think twice about ordering an MRI of the knee for patients with unclear knee symptoms. In a companion article7 in this issue, Englund and colleagues present their study of 991 middle-aged and elderly people who had MRIs of their right knee. Among women 50-59 years old, 19% had a meniscal tear or destruction, and for men 70-90 years old, the prevalence was 56%. Most (61%) did not have any knee symptoms during the previous month. Among people with radiologic evidence of OA, there was no significant difference in meniscal injury between those with symptoms (63%) and those without (60%). Among people without radiologic evidence of OA, 32% of those with symptoms had some meniscal injury, vs 23% of those without, which was statistically significant. So if your patient presents with knee symptoms and you get an X-ray that does not demonstrate OA, you have a 1 in 3 chance of finding a meniscal injury on MRI, but because the baseline prevalence is 23%, there is only a 9% chance that the injury is related to the symptoms.
References
1. Moseley JB, et al. A controlled trial of arthroscopic surgery for osteoarthritis of the knee. N Engl J Med 2002; 347:81-88.
2. Wilke AJ. Should 'my friend Arthur' have a visit from the scope? Intern Med Alert 2002;24:113-114.
3. Jackson RW. Arthroscopic surgery for osteoarthritis of the knee. N Engl J Med 2002;347:1717-1719.
4. Ewing W, Ewing JW. Arthroscopic surgery for osteo-arthritis of the knee. N Engl J Med 2002;347:1717-1719.
5. Chambers KG, Schulzer M. Arthroscopic surgery for osteo-arthritis of the knee. N Engl J Med 2002;347:1717-1719.
6. Marx RG. Arthroscopic surgery for osteoarthritis of the knee? N Engl J Med 2008;359:1169-1170.
7. Englund M, et al. Incidental meniscal findings on knee MRI in middle-aged and elderly persons. N Engl J Med 2008;359:1108-1115.
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