Novel classification for multi-ligament knee injury including both tibiofemoral joint factor and patellofemoral joint factor (193)
Authors: Tajima Takuya , Yamaguchi Nami , Morita Yudai , Yokoe Takuji , Chosa Etsuo 
Published: October 2021

Objectives: Multi-ligament knee injury (MLKI) shows very varied symptoms which was depended on the combination of injured ligaments. Schenck`s knee dislocation classification which was one of useful classifications for surgeon in decision making. However, Schenck`s classification is only referred to the factors of cruciate ligament and collateral ligament. It is well known that knee joint consists of two important structure; tibiofemoral joint and patellofemoral joint. Knee extensor structure is one of important factors of knee function. Dislocation of patella, quadriceps or patella tendon rupture are sometimes occurred in the knee trauma and provided severe instability or disability of knee function. Of course, these injuries were also target for consideration of treatment. Moreover, knee extensor structure disruption was sometimes combined with other knee ligaments such as cruciate or collateral ligament. Unfortunately, the case of combined cruciate or collateral ligament with knee extensor structure disruption could not classified in the previous classifications. Therefore, we proposed new classification for MLKI which contains both femorotibial factor and patellofemoral factor. We established and defined several categories in accordance with number of injured ligaments, combination of injured ligaments, and additional combined injury such as fracture, nerve injury, vascular injury. It was hypothesized that all cases at least two ligaments involved situation not only combination of tibiofemoral factor, but also including patellofemoral factor, could classify and divide into the new established classification. Methods: The present study was conducted in 2019, involving patient who was diagnosed MLKI at our institute. The study followed both retrospective and prospective observational design including data collected from Apr 2007 to Aug 2020. The experimental design was reviewed and approved (Accession No. 0-0602) by the Ethics Committee of our institute. The procedures followed were in accordance with the ethical standards of the responsible committee on human experimentation (institutional and national) and with the Helsinki Declaration of 1975, as revised in 2000. Inclusion criteria were the cases of two or more injured ligaments diagnosed clinically and by MRI testing and dynamic X-ray testing. Detail of ligament around knee joint were defined as follows; ‘cruciate ligaments` which contains ACL and PCL; ‘collateral ligaments` which contains MCL and posterolateral corner (PLC) certainly include lateral collateral ligament, and; ‘patellofemoral joint factor` which contains medial patellofemoral ligament (MPFL), quadriceps tendon and patellar tendon. Exclusion criteria was any prior knee surgery cases. Total 65 MLKI cases were met the inclusion criteria and were enrolled in this study. We focused on the number of injured ligaments, combination of the injured ligaments, and complication such as fracture, neurovascular injury. Based on the number of injured ligaments, 2 injured ligaments case was categorized as Type A, 3 injured ligaments case was as Type B, 4 ligaments case was as Type C, and 5 ligaments case was as Type D, respectively. We defined that injured ligament counting was follows; cruciate ligament group; ACL and/or PCL, collateral ligament group; MCL and/or PLC, and PF joint group; one of the MPFL or patellar tendon or quadriceps tendon. Depended on the combination of injured ligaments, each case was subdivided into 1 to 5 in Type A and B, into 1 to 3 in Type C. Additional injuries with MLKI were also subdivided as follows; MLKI with fracture case was defined as X, with neurovascular injury case was as Y, and both fracture and neurovascular injury case was as Z. (Table 1, 2, 3, and 4). For each case, final decision of injured ligament was recorded under clinical examination and image evaluation. MLKI cases were divided into both Schenk’s KD classification and the present new established classification. Results: Fifty-seven of 65 cases were divided into Schenck’s KD classification as follows; 19 cases of ACL+MCL and 13 cases of ACL+PLC and 9 cases of PCL+PLC and 2 cases of PCL+MCL as KD-?, 4cases of ACL+PCL as KD-? and one case of ACL+PCL with fracture as KD-?2, 6 cases of ACL+MCL, 2 cases of ACL+PCL+PLC as KD-?, and 1 case of ACL+PCL+MCL+MCL with fracture as KD-?5, respectively. Eight cases (12.3%) could not be divided into Schenk’s KD classification. Combination of these 8 cases were follows; 2 cases of PLC+MPFL, and single case of ACL+MCL+PLC, ACL+PCL+MCL+PLC+MPFL, ACL+MPFL, PCL+PLC+MPFL+ fracture, ACL+MCL+MPFL, and PCL+ patella tendon, respectively. Seven of 8cases contained PF joint factor injury. At the established new classification for MLKI, all 65 cases were divided into each category, successfully. PLC+MPFL was divided into Type-A5, ACL+MCL+PLC was Type-B2, ACL+PCL+MCL+PLC+MPFL was Type-D, ACL+MPFL was Type-A4, PCL+PLC+MPFL was Type-B3-X, ACL+MCL+MPFL was Type-B3, and PCL+ patella tendon was Type-A4. Conclusions: Several classification systems have been reported for diagnosis of MLKI cases. Kennedy `s classification and the French Society of Orthopedic Surgery and Traumatology 2008 classification were focused on the mechanism and direction of dislocation. These classifications were available for understanding comprehension mechanism of injured knee. However, previous classifications including Schenck’s classification were lack of PF joint factor. It is very important for knee surgeon that understanding injured mechanism as well as number of injured ligaments and combination of injured ligaments for decision making for surgery. The present classification was useful for MLKI case which contains both tibiofemoral factor and patellofemoral factor.