Table 1. Baseline Characteristics of the Intention-to-Treat Population.
| No. (%) | ||
|---|---|---|
| APM Group (n = 158) |
PT Group (n = 161) |
|
| Demographics | ||
| Age, mean (SD), y | 57.6 (6.5) | 57.3 (6.8) |
| Women | 80 (50.6) | 81 (50.3) |
| Right knee | 88 (55.7) | 81 (50.3) |
| Education level, beyond high schoola | 67 (42.4) | 86 (53.4) |
| BMI, mean (SD) | 26.7 (3.8) | 27.2 (4.0) |
| 18.5<BMI<25 | 56 (35.4) | 53 (32.9) |
| 25≤BMI<30 | 72 (45.6) | 67 (41.6) |
| 30≤BMI<35 | 30 (19.0) | 41 (25.5) |
| Mechanical complaintsb | 56 (35.4) | 67 (41.6) |
| Imagingc | ||
| Affected meniscus | ||
| Medial | 126 (79.7) | 136 (84.5) |
| Lateral | 30 (19.0) | 25 (15.5) |
| Both | 2 (1.3) | 0 (0) |
| Type of tear on MRI (ISAKOS23) | n = 151 | n = 152 |
| Longitudinal-vertical | 5 (3.3) | 5 (3.3) |
| Horizontal | 80 (53.0) | 69 (45.4) |
| Complex degenerative | 47 (31.1) | 58 (38.1) |
| Radial | 13 (8.6) | 10 (6.6) |
| Vertical flap | 2 (1.3) | 5 (3.3) |
| Unclassifiable | 1 (0.7) | 5 (3.3) |
| Horizontal flap | 3 (2.0) | 0 (0) |
| Osteoarthritis score on radiographs (KL classification14)d | n = 150 | n = 149 |
| 0: None | 18 (12.0) | 15 (10.1) |
| 1: Doubtful | 81 (54.0) | 74 (49.7) |
| 2: Minimal | 45 (30.0) | 55 (36.9) |
| 3: Moderate | 6 (4.0) | 5 (3.3) |
| Knee Function and Pain | ||
| Knee function | ||
| IKDC score (0 [most limitations] to 100 [no limitations]), mean (SD)e | 44.8 (16.6) | 46.5 (14.6) |
| Knee pain | n = 145 | n = 151 |
| VAS during weight-bearing (0 [no pain] to 100 [worst pain imaginable]), median (IQR)f | 61.1 (44.9-83.4) | 59.3 (44.9-77.4) |
Abbreviations: APM, arthroscopic partial meniscectomy; BMI, body mass index (calculated as weight in kilograms divided by height in meters squared); IKDC, International Knee Documentation Committee; IQR, interquartile range; ISAKOS, International Society of Arthroscopy, Knee Surgery, and Orthopedic Sports Medicine; KL, Kellgren-Lawrence; MRI, magnetic resonance imaging; PT, physical therapy; VAS, visual analog scale.
Education level was measured according to the International Standard Classification of Education (ISCED) and dichotomized to low (ISCED level 0-3; eg, early childhood education, primary education, or high school) or high (ISCED level 4-8; eg, any education beyond high school, including bachelor’s, master’s, or doctoral degree).24
In contrast to locking of the knee joint, which was an exclusion criterion, mechanical complaints, such as clicking or catching, were allowed for inclusion.
All participants underwent MRI prior to inclusion, and information on the affected meniscus was based on clinical readings by different radiologists and orthopedic surgeons in participating centers. The type of tear was based on post-hoc readings of the MRIs by one radiologist, and osteoarthritis scores were based on study readings of the MRIs by one other radiologist. Some radiographs and MRIs were unavailable (8 and 7 for APM and 12 and 9 for PT, respectively) for study readings.
KL grade 0 (no osteophytes or joint-space narrowing) indicates no osteoarthritis, grade 1 (questionable osteophytes) indicates early-onset osteoarthritis, grade 2 (definite osteophytes, possible joint-space narrowing) indicates mild osteoarthritis, grade 3 (moderate osteophytes, definite joint-space narrowing, some sclerosis, possible bone-end deformity) indicates moderate osteoarthritis, and grade 4 (large osteophytes, marked joint-space narrowing, severe sclerosis, definite bone ends deformity) indicates severe osteoarthritis.14 KL grade 4 was an exclusion criterion.
IKDC scores range from 0 to 100, in which 0 indicates the highest level of knee symptoms and lowest level of function in daily or sporting activities, and 100 indicates the lowest knee symptoms and highest level of function in daily or sporting activities. Normative mean (SD) values for the IKDC in the United States are 88 (14) for men aged 51 to 65 years and 85 (16) for women aged 51 to 65 years in a population without current knee problems or a history of knee surgery. In a mixed population of people with and without current knee problems, the normative mean (SD) scores are 77 (23) for men aged 51 to 65 years and 71 (26) for women aged 51 to 65 years.19 For example, a patient scores 50.6 on the IKDC if the highest level of activities and the effect of the knee on activities are graded as “moderate” for all asked activities, the level of knee pain is “moderate” (5 of 11), mechanical complaints are absent, and the current knee function is graded as “moderate” (5 of 11).
VAS score ranged from 0 to 100, and was anchored as 0 indicating no pain and 100 indicating maximum pain.