Summary

Description of the development of the „Warsaw“ classification system which has been designed as a tool for clinicians and radiologists allowing to properly identify and assess the extent of the damage to the posterior tibial plateau and decide further surgical treatment.

Abstract

Introduction

Bone bruises (BB) of the posterior margin of the tibia are commonly observed in patients with anterior cruciate ligament (ACL) injuries (64-94%). Depending on the amount of force and mechanism of injury the extent of the damage may vary from light to moderate bruising, however in more severe cases a compression fracture occurs. The authors' observations and research combined with current literature review indicate that the disruption of the articular surface dedicated for the lateral meniscus (LM) movement may affect knee biomechanics, creating an environment for the occurrence of early-onset osteoarthritis.

Material & Methods
A retrospective study covered cases from 2 European orthopaedic centres. Based on the inclusion criteria, 589 cases (209 female and 254 male patients) with acute complete ACL rupture were assigned to the study group followed by the retrieval of relevant MRI scans. MRIs were done in all available planes, however only axial and coronal STIRs along with sagittal PD images (allowing to visually analyse the position of lateral meniscus on the plateau as a reference point for the observer) were taken into consideration while establishing the classification.
Further prospective observation of cases in which posterolateral tibia fracture (PTF) grade III/IV is ongoing. Patients report for physical examination and are monitored in CT (3 months post-op) and regular follow-up MRIs to determine the ACL-R outcome, healing progress and overall stability and function of the operated joint.

Results

Considering radiological evaluation and input a 4-grade classification has been proposed: grade I - oedema resulting from the contusion of the bone, no changes in the bone shape; grade II - slight compression with the meniscus still fully supported; grade III - bone degradation, only about 50% support for the meniscus; grade IV - less than 50% tibial LM support.
Based on the visual assessment, out of 589 patients BB were found in 463 cases (78,60%). Identified BB cases were subsequently classified as follows: grade I - 94 (20,30%); grade II - 270 (58,31%); grade III - 73 (15,75%); grade IV - 26 (5,61%).

Conclusions&Clinical Relevance
The proposed classification - if accepted by the orthopaedic community, could significantly aid surgeons while deciding surgical treatment at the time of ACL injury. Timely identification of the need for comprehensive surgical treatment could minimise the risk of maintaining knee instability or early-onset osteoarthritis. In the authors' opinion, grades III and IV (amounting to 21,37% of cases covered by this study) require the reduction of the compressed bone at the time of ACL reconstruction. The surgeries done to date show excellent results in terms of patient’s stability and recovery rate.