Patient reported outcome measures in anterior cruciate ligament rupture and reconstruction: The significance of outcome score prediction

BACKGROUND: Numerous anterior cruciate ligament (ACL) clinical outcome measures exist. However, the result of one score does not equate to the findings of another even when evaluating the same patient group. AIM: To investigate if statistically derived formulae can be used to predict the outcome of one knee scoring system when the result of another is known in patients with ACL rupture before and after reconstruction. METHODS: Fifty patients with ACL rupture were evaluated using nine clinical outcome measures. These included Tegner Activity Score, Lysholm Knee Score, Cincinnati Knee Score, International Knee Documentation Committee (IKDC) Objective Knee Score, Tapper and Hoover Meniscal Grading Score, IKDC Subjective Knee Score, Knee Outcome Survey - Activities of Daily Living Scale (KOS-ADLS), Short Form-12 Item Health Survey and Knee Injury and Osteoarthritis Outcome Score. Thirty-four patients underwent an ACL reconstruction and were reassessed post-operatively. RESULTS: The mean total of each of the nine outcome scores appreciably differed from each other. Significant correlations and regressions were found between most of the outcome scores and were stronger post-operatively. The strongest correlation was found between Cincinnati and KOS-ADLS (r = 0.91, P < 0.001). The strongest regression formula was also found between Cincinnati and KOS-ADLS (R(2) = 0.84, P < 0.001). CONCLUSION: The formulae produced from this study can be used to predict the outcome of one knee score when the results of the other are known. These formulae could facilitate the conduct of systematic reviews and meta-analysis in studies relating to ACL injuries by allowing the pooling of substantially more data.