Table 1 Patient demographic of 186 hips
Parameter |  | Cases; LLD > = 5 mm | Controls; LLD < 5 mm | p-value |
|---|---|---|---|---|
Number | n | 84 | 102 | Â |
Post-operative LLD (mm) | Mean (SD) | 9.7 (3.2) | 1.2 (2.9) | < 0.001 |
Gender | n (%) | Â | Â | Â |
 Female |  | 44 (52.4%) | 46 (45.1%) | 0.323 |
 Male |  | 40 (47.6%) | 56 (54.9%) |  |
Age (years) | Mean (SD) | 58.4 (12.4) | 59.1 (13.1) | 0.739 |
BMI (kg/m2) | Mean (SD) | 24.2 (3.8) | 24.6 (3.8) | 0.534 |
Laterality | n (%) | Â | Â | Â |
 Right |  | 46 (54.8%) | 57 (55.9%) | 0.878 |
 Left |  | 38 (45.2%) | 45 (44.1%) |  |
Cause of Osteonecrosis | n (%) | Â | Â | Â |
 Alcohol abuse |  | 22 (26.2%) | 30 (29.4%) | 0.544 |
 Use of glucocorticoids |  | 9 (10.7%) | 12 (11.8%) |  |
 Sickle cell anemia |  | 0 (0%) | 2 (2.0%) |  |
 Systemic lupus erythematosus |  | 0 (0%) | 1 (1.0%) |  |
 Radiation treatment |  | 0 (0%) | 1 (1.0%) |  |
 Unidentified |  | 53 (63.1%) | 56 (54.9%) |  |
Dorr classification | n (%) | Â | Â | Â |
 Type A |  | 17 (20.2%) | 13 (12.7%) | 0.292 |
 Type B |  | 46 (54.8%) | 56 (54.9%) |  |
 Type C |  | 21 (25.0%) | 33 (32.4%) |  |
Pre-operative LLD (mm) | Mean (SD) | -3.2 (5.1) | -7.9 (5.8) | < 0.001 |
Femoral neck resection (mm) | Mean (SD) | 20.6 (4.6) | 20.8 (5.9) | 0.734 |
Acetabular cup size | Median [range] | 52 [46, 62] | 52 [46, 62] | 0.052 |
Femoral stem size | Median [range] | 4 [1, 10] | 5 [1, 10] | 0.087 |
Ceramic head size | n (%) | Â | Â | 0.143 |
 28 mm |  | 42 (50.0%) | 43 (42.2%) |  |
 32 mm |  | 36 (42.9%) | 45 (44.1%) |  |
 36 mm |  | 6 (7.1%) | 14 (13.7%) |  |
Neck length | n (%) | Â | Â | 0.906 |
 Short |  | 1 (1.2%) | 2 (2.0%) |  |
 Medium |  | 68 (81.0%) | 81 (79.4%) |  |
 Long |  | 15(17.9%) | 19 (18.6%) |  |
The amount of lengthening (mm) | Mean (SD) | 12.9 (5.3) | 9.2 (6.0) | < 0.001 |
Cup center respect to GT (mm) | Median [range] | 0.0 [-8.9, 27.6] | -1.4 [-18.7, 10.3] | 0.164 |