Baseline characteristics in patients undergoing high tibial osteotomy, with or without conversion to total knee replacement*
| Characteristic | No. (%) of HTO procedures† n = 643 | No. (%) of HTO procedures with conversion to TKR† n = 103 | No. (%) of HTO procedures without conversion to TKR† n = 540 |
|---|---|---|---|
| Age, yr; mean ± SD | 46.9 ± 9.0 | 50.2 ± 6.7 | 46. 3 ± 9.3 |
| Sex, male | 498 (77.5) | 72 (70.0) | 426 (79.0) |
| Body mass index, kg/m2; mean ± SD | 29.7 ± 5.1 | 31.0 ± 5.6 | 29.5 ± 5.0 |
| Correction size, mm;‡ mean ± SD | 11.5 ± 3.2 | 12.2 ± 3.2 | 11.4 ± 3.2 |
| Preoperative mechanical axis angle, °;§ mean ± SD | −7.9 ± 3.7 | −8.7 ± 3.9 | −7.8 ± 3.6 |
| Postoperative mechanical axis angle, °;§¶ mean ± SD | 0.9 ± 2.6 | 0.2 ± 3.1 | 1.1 ± 2.5 |
| KOOS Pain subscale score;** mean ± SD | 53.2 ± 19.5 | 46.3 ± 18.7 | 54.5 ± 19.4 |
| Kellgren and Lawrence grade†† | |||
| 0 | 4 (0.6) | 0 (0.0) | 4 (0.7) |
| 1 | 68 (10.6) | 1 (1.0) | 67 (12.4) |
| 2 | 193 (30.1) | 15 (14.6) | 178 (33.0) |
| 3 | 244 (38.0) | 50 (48.5) | 194 (35.9) |
| 4 | 134 (20.8) | 37 (35.9) | 97 (18.0) |
| Osteoarthritis Research Society International Joint Space Narrowing grade‡‡ | |||
| Medial tibiofemoral compartment | |||
| 0 | 14 (2.2) | 0 (0.0) | 14 (2.7) |
| 1 | 184 (29.4) | 19 (19.2) | 165 (31.4) |
| 2 | 251 (40.2) | 40 (40.4) | 211 (40.1) |
| 3 | 176 (28.2) | 40 (40.4) | 136 (25.9) |
| Lateral tibiofemoral compartment | |||
| 0 | 524 (83.8) | 86 (86.8) | 438 (83.3) |
| 1 | 91 (14.6) | 12 (12.1) | 79 (15.0) |
| 2 | 9 (1.4) | 1 (1.0) | 9 (1.7) |
| 3 | 1 (0.2) | 0 (0.0) | 0 (0.0) |
Note: HTO = high tibial osteotomy, KOOS = Knee injury and Osteoarthritis Outcome Score, SD = standard deviation, TKR = total knee replacement.
↵* All patients had a clinical diagnosis of knee osteoarthritis according to the American College of Rheumatology Criteria as described by Altman and colleagues. (50) Clinical knee osteoarthritis is defined as knee pain and 3 of the 6 following criteria: morning stiffness < 30 minutes, age > 50 years, crepitus, bony tenderness, bony enlargement or no palpable warmth.
↵† Unless specified otherwise.
↵‡ Wedge size for HTO.
↵§ A negative angle indicates varus alignment and a positive angle indicates valgus alignment.
↵¶ Correction achieved during surgery, measured during postoperative examination.
↵** A score of 0 indicates extreme knee symptoms; 100 indicates no knee symptoms.
↵†† The Kellgren and Lawrence grade evaluates the degree of radiographic osteoarthritis severity. A grade of 0 indicates a normal knee; grade 1 indicates doubtful joint space narrowing and possible osteophytic lipping; grade 2 indicates possible joint space narrowing and definite osteophytes; grade 3 indicates definite joint space narrowing, multiple moderate osteophytes, some sclerosis and possible deformity of the bone contour; and grade 4 indicates marked joint space narrowing, large osteophytes, severe sclerosis and definite deformity of bone contour.
↵‡‡ The Osteoarthritis Research Society International (OARSI) Radiographic Atlas for Osteoarthritis is a semiquantitative scoring system that includes compartment-specific joint space narrowing grades on a scale of 0 (normal joint space) to 3 (total loss of joint space). Grading using OARSI was available for 625 of the 643 knee procedures.