Background/Purpose: Clinicians are challenged to identify those patients with knee pain, osteoarthritis (OA) and imaging evidence of a meniscal tear (MT) who are likely to benefit from arthroscopic partial meniscectomy (APM). Traditionally, clinicians have recommended that patients with “mechanical symptoms” (e.g. locking, clicking, catching) consider APM. The MeTeOR (MT in OA Research) Trial demonstrated similar symptomatic relief in persons treated with APM and those treated initially with physical therapy (PT), with referral for APM if PT did not relieve pain. We analyzed MeTeOR data to compare improvement in mechanical symptoms between subjects that received APM and those that received PT; and to examine whether frequency of baseline mechanical symptoms influenced pain relief at 6 month follow-up.

Methods: MeTeOR is a seven-center RCT of APM vs. standardized PT in subjects age 45+ with symptomatic MT and OA. The baseline survey asked about 5 mechanical symptoms (clicking, catching, popping, locking, giving way), each with 5 responses (“never” to “several times a day”). We summed these 5 items to create a mechanical symptom score. We used t-tests to compare patients who had surgery (at the outset or after crossing over) vs. those treated with PT with respect to changes in mechanical symptom score from baseline to 6 months. We compared baseline mechanical symptom scores with changes over 6 months in WOMAC Pain using correlations (presented as crude r-squared).  We used multivariable linear regression with an interaction to assess whether the association between baseline mechanical symptom score and improvement in WOMAC Pain over 6 months differed between subjects treated with APM vs. those treated with PT.

Results:   351 subjects participated, 57% female, mean age 58.The baseline mean mechanical symptom score was 10.4 (SD 4.9) and mean WOMAC Pain 41.0 (SD 17.8, possible range 0-100 with 0=best). Subjects improved in WOMAC Pain over 6 months by a mean of 21.4 points (SD 18.7). Improvement over 6 months in mechanical symptom score was greater among subjects treated with APM (0.82 SD’s) than among those treated with PT (0.42 SD’s; p=0.01). However, improvement in mechanical symptom score explained just 8% of variability in improvement in WOMAC Pain. We did not find an association between baseline mechanical symptom score and improvement in WOMAC Pain (r-squared <0.02 for both APM- and PT-treated subjects.) Associations between individual symptom frequencies (e.g. locking, catching) and change in WOMAC pain and function scores were also negligible. The association of baseline mechanical symptom score and change in pain score did not differ between subjects receiving APM and those receiving PT (p for interaction=0.44).

Conclusion: While mechanical symptom scores improved more following APM than following PT, MeTeOR data did not support the clinical teaching that frequent mechanical symptoms at baseline predict greater pain relief following APM than following PT.  Thus, clinicians should not rely upon the frequency of mechanical symptoms to predict pain relief following APM but can advise their patients that mechanical symptoms are more likely to resolve with surgery than without.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/influence-of-mechanical-symptoms-on-treatment-outcomes-for-meniscal-tear-in-the-setting-of-osteoarthritis/