Summary

In the setting of MLKI, MRI and clinical signs of patella dislocation are as high as 28.8%.

Abstract

Introduction

Multiligament knee injury (MLKI), including knee dislocation (KD) poses a major trauma for the patient. The timing of the management, acute or delayed, as well type of management, repair or reconstruct, including the type of reconstruction, are all dependent on a number of factors. Equally, the management of isolated patellar dislocation has a specific treatment regime by its own right. What is currently unknown in the literature is the incidence of concomitant patella dislocation in a setting of MLKI. The importance of understanding the incidence adds to the understanding of concomitant injuries that are a consequence of the dislocated patella, rupture of the medial patellofemoral ligament (MPFL) and cartilage lesions of the lateral condyle and the patella. The present study aimed to investigate the incidence of patellar dislocation in the setting of MLKI.

Methods

A retrospective MRI and operative note review of two major trauma centers for the years 2016-2023 was performed. Included were all MLKIs, defined as a disruption of at least two major knee ligaments, anterior cruciate (ACL), posterior cruciate (PCL), medial collateral (MCL) and lateral collateral (LCL) ligaments. Injuries were classified in either ACL- or PCL- based.
All cases had a preoperative MRI and were treated surgically. Patella dislocation on MRI was defined as: 1) Obviously dislocated patella 2) lateralization at least 2/3 with a bone bruise/cartilage injury of the patella, lateral condyle or both, 2) Bony or intrasubstance MPFL rupture with or without a bone bruise/cartilage injury of the patella, lateral condyle or both. Number of MPFL reconstructions was recorded out of the operative notes.

Results

A total of 364 MKLIs were included in the study, 186 from the first center, 178 from the second. PCL-based injury was present in 156 cases (42.9%). Disruption of the MPFL ligament was observed in 75 cases (20.6%). Lateralization of the patella in combination with bone bruise/cartilage injury was observed in another 30 cases (8.2%). An MPFL reconstruction was performed in 15 cases, in 2 cases a repair was performed (4.7%).

Discussion And Conclusion

In the setting of MLKI, MRI and clinical signs of patella dislocation are as high as 28.8%. The extend of the injury, however, does not allow for a proper clinical examination preoperatively and, equally, the primary focus is on the major 4 ligaments. The present study demonstrates that patellar dislocation frequently gets overlooked in the setting of MLKI and gets treated even less frequently. The clinical relevance of currently diagnosing and managing patellar dislocation in the setting of MLKI requires further research.