Surgical group: comparison of 1974–82 and 1991–96 cohorts
| 1974–82 cohort (n=32) | 1991–96 cohort (n=27) | |
| Number of operations | 40 | 31 |
| Mean follow up (months) | 60 (24–108) | 26.4 (5–78) |
| Demographic details | ||
| M:F ratio | 1:3 | 1:8 |
| Median age (years) | ⩾60 (range 46–74) | 58 (23–81) |
| Median disease duration (years) | ⩾18 (2–40) | 16 (3–49) |
| Clinical features (%) | ||
| RF positive | 66 | 100 |
| Receiving prednisolone | 34 | 15 |
| Indication for surgery (%) | ||
| Pain + neurological deficit | 44 | 67 |
| Neurological deficit only | 44 | 11 |
| Pain only | 13 | 22 |
| Ranawat grade (No (%)) | ||
| I | 4 (12) | 5 (18) |
| II (mild) | 11 (34) | 12 (44) |
| IIIA (moderate) | 6 (19) | 5 (18) |
| IIIB (severe) | 11 (34) | 2 (7) |
| Mortality (No (%)) | ||
| No of deaths—early | 3 (9) | 0 |
| No of deaths—late | 13 (41) | 2 (7) |
| Morbidity | ||
| None | 16 | 21 |
| Failure of fusion | 9 | 4 |
| Wound infection | 4 | 0 |
| Loosening of fixator | 0 | 1 |
| Deep infection/abscess | 1 | 1 |
| Other | 2 | 0 |