Table 1

Baseline characteristics of the participants allocated to APM or placebo surgery

Placebo surgery
 Female28 (40)29 (38)
 Male42 (60)47 (62)
Age (years)52.1±6.952.0±7.2
Body mass index (kg/m2)26.9±4.027.9±4.0
Duration of symptoms (months)10 (3–50)10 (3–47)
Kellgren-Lawrence grade*
 018 (26)25 (33)
 140 (57)37 (49)
 212 (17)14 (18)
 OARSI sum score†1.9±1.21.7±1.3
Meniscal tests
 Positive McMurray test‡16 (23)15 (20)
 Pain provoked by forced flexion and compression50 (71)59 (78)
 Pain provoked by palpation at the joint line63 (90)74 (97)
 Symptoms of catching or locking32 (46)37 (49)
 WOMET score§56.4±17.352.8±18.1
 Lysholm score¶60.2±14.760.1±14.6
 Pain after exercise (VAS)**5.8±2.06.1±2.0
  • Values are numbers (percentages), means±SD or medians (ranges).

  • *Kellgren and Lawrence scale is a radiographic classification of the severity of knee osteoarthritis. Grade 0 denotes no osteoarthritis, grade 1 possible osteoarthritis, and grade 2 mild osteoarthritis. Scoring based on a consensus reading of two experienced musculoskeletal radiologists blinded to treatment allocation and clinical data.

  • †The sum of marginal tibiofemoral osteophyte grades and tibiofemoral joint space narrowing (JSN) grades based on the atlas by the Osteoarthritis Research Society International (OARSI) (continuous outcome, hypothetical range 0–18).

  • ‡Results of a McMurray test are positive if a “click” over the medial tibiofemoral joint line is felt by the examiner during flexion and extension of the knee under varus stress.

  • §The Western Ontario Meniscal Evaluation Tool (WOMET) contains 16 items addressing three domains: 9 items addressing physical symptoms; 4 items addressing disabilities with regard to sports, recreation, work, and lifestyle; and 3 items addressing emotions. The score indicates the percentage of a normal score; therefore, 100 is the best possible score, and 0 is the worst possible score.

  • ¶The Lysholm knee score is based on an eight-item questionnaire designed to evaluate knee function and symptoms in activities of daily living. Scores range from 0 to 100; higher scores indicate less severe symptoms.

  • **Knee pain after exercise (during the preceding week) was assessed on a rating scale of 0 to 10, with 0 denoting no pain and 10 denoting extreme pain.

  • APM, arthroscopic partial meniscectomy; VAS, Visual Analogue Scale.