Operative treatment of primary patellar dislocation does not improve medium-term outcome - A 7-year follow-up report and risk analysis of 127 randomized patients

Background: The best treatment for primary patellar dislocation has been the subject of debate. Surgery has been recommended for all patients or for special subgroups to improve outcome. We have previously reported similar 2-year results after closed or open treatment. This report concerns 127 patients who were re-evaluated by questionnaire at least 5 years after the primary onset. Patients and methods: At baseline, the patients were randomized regarding closed treatment (57) or individually adjusted proximal realignment operation (70). All patients were re-evaluated after a mean follow-up of 7 (6-9) years. Results: The outcomes were similar: the patient's own overall opinion was excellent or good after closed treatment in 81 % of cases and after operative treatment in 67%. Mean Kujala and Hughston VAS knee scores were 90 and 94, respectively, after closed treatment and 88 and 89 after operative treatment. The proportions of stable patellae were 30% and 36% for closed treatment and operative treatment, respectively. In a multivariate risk analysis, there was a correlation between a Kujala score of less than 90 and female sex (OR: 3.5; 95% Cl: 1.4-9.0), loose bodies on radiographs (4.1; 1.2-15), and also an initial history of contralateral patellar instability (3.6; 0.9-15). There were 2 risk factors for recurrent instability: initial contralateral instability (4.9; 0.9-28) and young age (0.9; 0.8-1.0/year). Girls with open tibial apophysis had the worst prognosis for instability (88%; 95% CI: 77-98). Interpretation: We do not recommend proximal realignment surgery for treatment of primary dislocation of the patella.