Pain dominates summed scores for hindfoot and ankle trauma

Outcomes in clinical orthopaedic research are often presented as a summed functional score, without the individual component scores. Thus, there is little information about the effect of each component score on the overall score in hindfoot and ankle trauma. The purpose of this study was to determine which subscores were most responsible for the overall variation in summed scores and to evaluate the correlation of multiple scoring systems after foot and ankle fractures or reconstruction.

One hundred fifty-eight patients were evaluated after open reduction internal fixation of the calcaneus, open reduction internal fixation of the plafond, or ankle fusion with the Short Form 36, American Orthopedic Foot and Ankle Society (AOFAS), and Maryland scoring systems. Correlations were made between summed scores using a Pearson correlation matrix and the percentage of overall variation of the summed score that is accounted for by the answer to the pain question within the score.

For all 3 subsets of patients, there was strong statistical correlation of the Short Form 36 physical component summary, AOFAS, and Maryland scores (P < 0.001). The strongest correlation was between the AOFAS and the Maryland scores for each subset: calcaneus (r = 0.957, P < 0.0001), pilon (r = 0.946, P < 0.0001), and ankle fusion (r = 0.944, P < 0.0001). The pain subscore accounted for almost the entire variation in the summed score, being responsible for 80% to 86% of the overall variation. There was minimal change in overall variation when physical examination was factored into the analysis.

Pain dominates the variation in summed scores for hindfoot and ankle trauma and reconstruction. We strongly recommend that when summed scores are used that the individual components are reported.