Combining preoperative expectations and postoperative met expectations to predict patient-reported outcomes after knee surgery

Introduction: Both preoperative expectations and postoperative met expectations can independently influence patient-reported outcomes (PROs), however, their combined effect on PROs is not well understood. This study aimed to determine the prognostic significance of categorizing non-arthroplasty knee surgery patients into clusters based on both preoperative expectations and postoperative met expectations. Methods: 638 patients who underwent non-arthroplasty knee surgery from June 2015 to May 2021 at a single academic institution were analyzed. Patients were grouped based on both preoperative expectations and two-year postoperative met expectations scores using cluster analysis. Four distinct expectations cluster groups were formed: high preoperative-high met expectations (HIGH-HIGH), low preoperative-high met expectations (LOW-HIGH), high preoperative-low met expectations (HIGH-LOW), and low preoperative-low met expectations (LOW-LOW). Socioeconomic data and PROs were compared based on cluster group, and logistic regression was performed to determine the likelihood of achieving a patient-perceived "completely better" status based on cluster group. Results: Patients with high met expectations, regardless of preoperative expectations, reported better two-year PROs compared to patients with low met expectations. Patients with high preoperative expectations achieved better outcomes only when those expectations were met postoperatively. Low preoperative expectations did not preclude patients from achieving good outcomes, as long as those expectations were met. The HIGH-HIGH group had increased odds of achieving completely better status compared to the LOW-HIGH group (OR = 1.68, p = .02), HIGH-LOW group (OR = 16.69, p < .001), and LOW-LOW group (OR = 5.17, p < .001). The HIGH-LOW group had decreased odds of achieving completely better status compared to the LOW-LOW group (OR = .31, p = .01). Conclusion: Met expectations may be a stronger predictor of postoperative outcomes than preoperative expectations in non-arthroplasty knee surgery. This study highlights the importance of setting realistic preoperative expectations and focusing on achieving expectations postoperatively. These findings offer valuable insights for clinicians to manage patient expectations effectively based on individual characteristics and expected treatment outcomes.