Abstract
BackgroundA 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.MethodsPatients 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.ResultsA 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%.ConclusionAn axial global PATS of 1.2 mm on MRI is greatly specific for identifying a functionally deficient ACL in patients with advanced AMOA.
Highlights
A functionally deficient anterior cruciate ligament (ACL) is considered one of the contraindications in unicompartmental knee arthroplasty (UKA)
Better clinical outcome of UKA comes with appropriate patient selection, in which patients with lateral compartment cartilage defect, functionally deficient anterior cruciate ligament (ACL), and severe knee deformity are contraindicated for Oxford UKA [3, 4]
Patients with ACL complete tear on magnetic resonance imaging (MRI) (n = 6), ACL status not. Both the measurements of medial passive anterior tibial subluxation (PATS) and lateral PATS showed excellent intra-observer agreements considering the intraclass correlation coefficient (ICC) were greater than 0.99 (Table 2)
Summary
A functionally deficient anterior cruciate ligament (ACL) is considered one of the contraindications in unicompartmental knee arthroplasty (UKA). 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. Better clinical outcome of UKA comes with appropriate patient selection, in which patients with lateral compartment cartilage defect, functionally deficient anterior cruciate ligament (ACL), and severe knee deformity are contraindicated for Oxford UKA [3, 4]. Direct observation of ACL’s texture and continuity on magnetic resonance imaging (MRI) in the degenerative knee may exaggerate the extent of ACL injury and exclude the potential UKA candidates with functionally intact ACL [8, 9]. The presence of posterior tibial bony erosion on the lateral radiograph is an indicator for identifying insufficient ACLs, this parameter is hard to quantify and subject to subjectivity and knee malposition [6, 10, 11]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
