Table 1 Characteristics of the subjects and the study populations by MRI signal grade of menisci (N = 124)
From: Risk factors for lesions of the knee menisci among workers in South Korea’s national parks
| Variables | Number of subjects | MRI signal grade of meniscia | ||||
|---|---|---|---|---|---|---|
| Grade 0-1 | Grade 2-3 | P-value* | ||||
| N | % | N (%) | N (%) | |||
| General characteristics | ||||||
| Sex | Male | 116 | 93.5 | 48 (41.4) | 68 (58.6) | 0.361 |
| Female | 8 | 6.5 | 2 (25.0) | 6 (75.0) | ||
| Age (year) | <45 | 66 | 53.2 | 32 (48.5) | 34 (51.5) | 0.048 |
| ≥45 | 58 | 46.8 | 18 (31.0) | 40 (69.0) | ||
| Body mass index (BMI) (kg/m2) | <25 | 75 | 60.5 | 31 (41.3) | 44 (58.7) | 0.777 |
| ≥25 | 49 | 39.5 | 19 (38.8) | 30 (61.2) | ||
| Smoking | Never or past | 32 | 25.8 | 11 (34.4) | 21 (65.6) | 0.426 |
| Current | 92 | 74.2 | 39 (42.4) | 53 (57.6) | ||
| Alcohol drinking | <1 times/week | 64 | 51.6 | 23 (35.9) | 41 (64.1) | 0.304 |
| ≥1 times/week | 60 | 48.4 | 27 (45.0) | 33 (55.0) | ||
| Regular exercise | Once a week or more | 109 | 87.9 | 46 (42.2) | 63 (57.8) | 0.250 |
| Less than once a week | 15 | 12.1 | 4 (26.7) | 11 (73.3) | ||
| Leisure activityb | No | 47 | 37.9 | 22 (46.8) | 25 (53.2) | 0.250 |
| Yes | 77 | 62.1 | 28 (36.4) | 49 (63.6) | ||
| Previous exercise-related knee injury | No | 90 | 72.6 | 37 (41.1) | 53 (58.9) | 0.771 |
| Yes | 34 | 27.4 | 13 (38.2) | 21 (61.8) | ||
| Previous accident-related knee injury | No | 78 | 62.9 | 36 (46.2) | 42 (53.8) | 0.085 |
| Yes | 46 | 37.1 | 14 (30.4) | 32 (69.6) | ||
| Previous work-related knee injury | No | 61 | 49.2 | 29 (47.5) | 32 (52.5) | 0.107 |
| Yes | 63 | 50.8 | 21 (33.3) | 42 (66.7) | ||
| Previous knee pain | No | 22 | 17.7 | 11 (50.0) | 11 (50.0) | 0.308 |
| Yes | 102 | 82.3 | 39 (38.2) | 63 (61.8) | ||
| Past medical historyc | No | 86 | 69.4 | 39 (45.4) | 47 (54.6) | 0.086 |
| Yes | 38 | 30.6 | 11 (28.9) | 27 (71.1) | ||
| Occupational characteristics | ||||||
| Overtime labor | No | 23 | 18.5 | 9 (39.1) | 14 (60.9) | 0.897 |
| Yes | 101 | 81.5 | 41 (40.6) | 60 (59.4) | ||
| Holiday use | Yes | 119 | 96.0 | 48 (40.3) | 71 (59.7) | 0.988 |
| No | 5 | 4.0 | 2 (40.0) | 3 (60.0) | ||
| Physical burden of workd | Low | 101 | 81.5 | 42 (41.6) | 59 (58.4) | 0.548 |
| High | 23 | 18.5 | 8 (34.8) | 15 (65.2) | ||
| Stair flighte | No | 92 | 74.2 | 41 (44.6) | 51 (55.4) | 0.103 |
| Yes | 32 | 25.8 | 9 (28.1) | 23 (71.9) | ||
| Kneelingf | No | 100 | 80.6 | 41 (41.0) | 59 (59.0) | 0.754 |
| Yes | 24 | 19.4 | 9 (37.5) | 15 (62.5) | ||
| The cumulative intensity of trekking 1 | <17 years | 67 | 54.0 | 34 (50.8) | 33 (49.2) | 0.010 |
| (= Tenure) | ≥17 years | 57 | 46.0 | 16 (28.1) | 41 (71.9) | |
| The cumulative intensity of trekking 2g | Low | 40 | 32.3 | 21 (52.5) | 19 (47.5) | 0.019 |
| Medium | 55 | 44.3 | 22 (40.0) | 33 (60.0) | ||
| High | 29 | 23.4 | 7 (24.1) | 22 (75.9) | ||
| The cumulative intensity of trekking 3h | Low | 42 | 33.9 | 23 (54.8) | 19 (45.2) | 0.006 |
| Medium | 65 | 52.4 | 24 (36.9) | 41 (63.1) | ||
| High | 17 | 13.7 | 3 (17.6) | 14 (82.4) | ||
| MRI scan area | Left knee | 59 | 47.6 | |||
| Right knee | 60 | 48.4 | ||||
| Both knees | 5 | 4.0 | ||||
| MRI signal grade of meniscii | 0 | 36 | 29.0 | |||
| 1 | 14 | 11.3 | ||||
| 2 | 57 | 46.0 | ||||
| 3 | 17 | 13.7 | ||||
| Location of menisci tear | No menisci tear | 50 | 40.3 | |||
| Lateral | 22 | 17.8 | ||||
| Medial | 52 | 41.9 | ||||
| Site of menisci tear | No menisci tear | 50 | 40.3 | |||
| Anterior horn | 11 | 8.9 | ||||
| Body of menisci | 5 | 4.0 | ||||
| Posterior horn | 58 | 46.8 | ||||
| Type of menisci tear | No menisci tear | 50 | 40.3 | |||
| Longitudinal | 0 | 0.0 | ||||
| Radial | 29 | 23.4 | ||||
| Horizontal | 43 | 34.7 | ||||
| Complex | 2 | 1.6 | ||||