Feasibility study of early prediction of postoperative MRI findings for knee stability after anterior cruciate ligament reconstruction

Evaluation of a New MRI-Based Classification of Graft Status After Superior Capsule Reconstruction

Background

A classification system for the graft state after superior capsule reconstruction (SCR) using magnetic resonance imaging (MRI) has not been described previously.

Purpose

To introduce a new, MRI-based classification system for graft integrity after SCR and to evaluate the system according to postoperative outcomes.

Study Design

Cohort study (diagnosis); Level of evidence, 3.

Method

Included were 62 consecutive patients who underwent SCR using autologous fascia lata graft between January 2013 and April 2021. Postoperative outcomes were assessed (American Shoulder and Elbow Surgeons [ASES] score, Constant score, pain visual analog scale [pVAS], range of motion [ROM], acromiohumeral distance [AHD], Hamada grade). Graft status was classified by 2 orthopaedic surgeons on postoperative MRI in accordance with the signal intensity and the presence or extent of the tear, as follows: type 1 (hypointense signal without tear), type 2 (hyperintense signal without tear), type 3 (partial-thickness tear), type 4 (full-thickness tear with partial continuity), and type 5 (full-thickness tear with complete discontinuity). Intra- and interobserver agreement were assessed using Cohen kappa. The correlation between postoperative outcomes (ASES score, Constant score, pVAS, ROM, AHD, and Hamada grade) and the SCR graft classification system was assessed with the Pearson correlation coefficient, and the outcomes were compared according to classification type.

Results

Patients were classified according to the new system as follows: type 1 (n = 15), type 2 (n = 20), type 3 (n = 7), type 4 (n = 8), and type 5 (n = 12). There was excellent interobserver agreement (κ = 0.819) and intraobserver agreement (κ = 0.937 and 0.919). The classification system showed a moderate to high correlation with the ASES score (r = -0.451; P = .001), pVAS (r = 0.359; P = .005), AHD (r = -0.642; P < .001), and Hamada grade (r = 0.414; P < .001). Patients classified as having types 1 and 2 showed better outcomes in terms of ASES score, pVAS, ROM, and AHD compared with type 5 patients (P ≤ .021 for all).

Conclusion

The new classification system was highly reproducible and showed clinical utility for both radiological and clinical evaluation after SCR.

Use of oblique sagittal and coronal weighted images for diagnosis and grading of ACL graft injury

Background

This study was done to evaluate the value of adding the oblique sagittal and oblique coronal MRI to the standard MRI knee protocol for evaluation of suspected ACL graft injuries.

Results

This was a cross-sectional analytic study where we reviewed 36 MRI knee examinations of 36 patients (30 males, 6 females, age range: 17–60 years, mean age: 26 years) who were subjected to ACL reconstruction and follow-up arthroscopy. Two experienced radiologists, blinded to the results of each other, evaluated the status and the severity of the ACL graft injury using the routine knee MRI (protocol A) and using the routine MRI after adding the oblique sagittal and coronal imaging (protocol B). Weighted kappa statistics were used to evaluate the diagnostic accuracies of the knee MRI before and after the addition of the oblique sagittal and coronal weighted images (protocol A and protocol B, respectively) and to assess the interobserver agreement. The weighted kappa values according to the routine knee MRI were 0.357 (reader 1) and 0.399 (reader 2). The inclusion of additional oblique coronal imaging increased the weighted kappa values to 0.505 (reader 1) and 0.528 (reader 2). The interobserver agreement weighted kappa value also increased from 0.606 to 0.759 by adding the oblique sagittal and coronal imaging to the routine knee MRI examination.

Conclusion

The additional use of oblique sagittal and coronal MRI of the knee improves the diagnostic accuracy for diagnosing and grading ACL graft injury with the arthroscopy used as a gold standard.