Preoperative PROMIS Physical Function Scores Predict Postoperative Outcomes Following Total Ankle Replacement

SLR - December 2021 - Steven Cooperman

Reference: Conti MS, Caolo KC, Cororaton AD, Deland JT, Demetracopoulos CA, Ellis SJ. Preoperative PROMIS Physical Function Scores Predict Postoperative Outcomes Following Total Ankle Replacement. Foot & Ankle Orthopaedics. July 2021. doi:10.1177/24730114211020335

Level of Evidence: III – Retrospective Comparative Series

Scientific Literature Review

Reviewed By: Steven Cooperman, DPM
Residency Program: Highlands/Presbyterian St. Luke’s Medical Center – Denver, CO

Podiatric Relevance: Total ankle arthroplasty/replacement (TAR) is an increasingly prevalent treatment for end-stage ankle arthritis. To date, many studies have demonstrated significant efficacy in relieving pain and improving physical function in large cohorts of patients, though there are still subsets of patients who do not experience improvement. Patient reported outcome measures may aid treating surgeons in pre-operative selection in order to further decrease the number of patients who do not experience relief. In this study, the Patient-Reported Outcome Measurement Information System (PROMIS) Physical Function Computerized Adaptive Test was used to determine if pre-operative PROMIS physical function, pain interference, pain intensity, and depression t scores were predictive of two-year improvement.

Methods: This retrospective study identified patients from a registry of prospectively collected data using CPT codes for TAR. Inclusion criteria included: patients who received a fixed-bearing TAR by three fellowship-trained foot and ankle orthopedic surgeons from a single academic institution for end-stage ankle arthritis between February 2016-2018. PROMIS scores were prospectively collected pre-operatively and at one-, two-, and five-years post-op. Minimal clinically important differences (MCIDs) for all domains were evaluated. Logistic regression analysis was performed to determine pre-operative PROMIS thresholds with sensitivity and specificity for the patients who achieved MCID.

Results: One hundred eleven feet in 105 patients met inclusion and exclusion criteria with an average follow up of 24.5 months. All domains had significant improvement, with greatest improvements in the pain intensity and interference domains. The MCID for the PROMIS physical function domain was 3.8, with 85.6 percent of the cohort achieving that at two years post-op. MCIDs for pain interference and intensity subscales were 5.0 and 4.8 respectively, with 81.8 percent and 89.5 percent of patients achieving these scores. The depression subscale MCID was 3.8, with only 37.4 percent of patients achieving this at two years post-op. For the logistic regression analysis pre-op PROMIS thresholds for sensitivity and specificity were as follows: Physical function, 36.2 and 26.4; pain intensity, 47.1 and 63.5; depression, 43.3 and 56.4.

Conclusions: While study limitations exist, such as the need for further validation of preliminary pre-operative PROMIS thresholds, this study appears to be a good start in the direction of identifying thresholds for predicting postoperative outcomes following TAR. This study found that pre-operative PROMIS physical function scores and pain intensity scores were predictive of meaningful clinical improvement from TAR, at 36.2 and 47.1 respectively. When comparing the findings of this study to those of PROMIS thresholds for hallux valgus patients undergoing bunionectomy, the higher threshold is seen in the bunionectomy group. This suggests that patients with more significant physical function limitations may achieve a higher benefit following TAR than those with less severe symptoms. However, delaying TAR due to higher physical function should be balanced with the knowledge that earlier intervention may retain more motion. Based on this, surgeons should strongly consider the implementation of routine use of patient reported outcome measures as an adjunctive tool to radiographic and clinical decision making when evaluating a patient for TAR. Additionally, this data can help guide future research regarding patient-reported outcomes following TAR as further validation is required.