Aims
To assess the pre- and postoperative responses to each of the 12 individual Oxford Knee Score (OKS) questions and percentages of those that were better, same or worse after primary knee arthroplasty (KA).
Methods
A single centre retrospective cohort study conducted over a 24-month period which included 3259 patients with completed OKS preoperatively and 1-year after KA. There were 1286 males and 1973 females, with an overall mean age of 70.0 (range 34–94). The mean scores for each question of the OKS were compared between baseline and 1-year. The percentage of patients who reported better, the same or worse postoperative symptoms for each question were calculated and represented on a heatmap.
Results
There were significant (p < 0.001) improvements in all 12 questions, all of which demonstrated moderate (Q2, Q7) or large effect sizes. Improvements in individual question responses varied. Symptoms of pain and limping demonstrated the greatest improvement, with 86% of patients enjoying a positive change in their symptoms. Despite this improvement 1067 (41.4%) continued to have mild to severe pain in their knee, and 442 (17.3%) patients limped often to all the time when walking postoperatively. Whereas other questions that did not improve to the same extent for example washing and drying only improved in 53% of patients but only 347 (13.5%) had moderate/extreme trouble or found it impossible to do this postoperatively. Preoperatively four questions (Q1, Q6, Q7, Q8) demonstrated floor effects, postoperatively all questions apart from question 7 (kneeling) demonstrated ceiling effects.
Conclusion
The mean improvement and outcome at 1-year for each of the 12 questions varied according to the patient’s preoperative response. As a clinical tool, the heatmap (improvement, same and worse) will enable communication to patients about their potential change in their knee specific symptoms according to their preoperative responses.
Level of evidence
Retrospective study, Level III.
