Value of passive anterior tibial subluxation on axial MRI in identifying anterior cruciate ligament functional deficiency in patients with advanced anteromedial osteoarthritis of the knee: a case-control study

Abstract

Background A functionally deficient anterior cruciate ligament (ACL) is considered one of the contraindications in unicompartmental knee arthroplasty (UKA). But there is still a lack of standardized and reproducible methods to assess ACL functional integrity in patients with advanced anteromedial osteoarthritis of the knee (AMOA). This study explores the value of passive anterior tibial subluxation (PATS) on axial MRI in evaluating ACL status in this population. Methods Patients who met UKA indications between November 2017 and September 2020 were included and grouped into “intact” (ACLI) or “deficient” (ACLD) group according to their ACL status during surgery. All participants underwent MRI with a standardized protocol. The measurements of medial and lateral PATS were conducted on axial MRI, and the mean of them was calculated as global PATS. Then the reliability and diagnostic ability of PATS were determined. Results A total of 85 patients (45 for ACLI group, 40 for ACLD group) were included after selection. The measurements of PATS showed excellent intra- and inter-observer reliabilities (with an intraclass correlation coefficient of at least 0.986). The global PATS of the ACLI group was significantly lower than that of the ACLD group (− 2.30 ± 1.96 vs. 1.03 ± 1.96 mm, P<0.0001). The diagnostic ability of global PATS was good (area under the curve = 0.897), and a threshold of 1.2 mm had a specificity of 100%, a sensitivity of 55%, and an accuracy of 78.82%. Conclusion An axial global PATS of 1.2 mm on MRI is greatly specific for identifying a functionally deficient ACL in patients with advanced AMOA.

A radiographic model predicting the status of the anterior cruciate ligament in varus knee with osteoarthritis

“…It was worth mentioning that the predictive model in our study had a higher accuracy (AUC = 0.949) than the predictive index (AUC = 0.897) of Tao et.al. [ 35 ], and higher sensitivity (96.2%) than the predictive index (55.0% and 93.3%) of Tao et.al. [ 35 ] and Johnson et.al.…”

“…Previous studies have reported the relationship between intraoperative findings of ACL and preoperative evaluations with physical examination, radiographs, or MRI [ 15 , 21 , 35 ]. Waldstein et.al.…”

“…Tao et.al. [ 35 ] found that an axial global passive anterior tibial subluxation (PATS) (> 1.2 mm) on MRI could be used as a predictive factor for a functionally deficient ACL, with the AUC, sensitivity, and specificity values of 0.897, 55% and 100%. Johnson et.al.…”

“…[ 35 ], and higher sensitivity (96.2%) than the predictive index (55.0% and 93.3%) of Tao et.al. [ 35 ] and Johnson et.al. [ 21 ].…”

Is conventional magnetic resonance imaging superior to radiography in the functional integrity evaluation of anterior cruciate ligament in patients with knee osteoarthritis?

“…However, there was no statistically significant difference in the diagnostic accuracy of a single parameter of radiography and MRI. A functionally-deficient ACL is currently considered to be contraindicated for UKA [ 18 ]. Therefore, whenever possible, preoperative MRI should be performed to help evaluate the ACL functional integrity and optimize subsequent operative plans.…”