Evaluation of the relationship between non-contact anterior cruciate ligament rupture and eminential morphometry: a cross-sectional and MRI based study

Abstract

Background

The literature does not clearly convey the relationship between eminential morphometry and non-contact anterior cruciate ligament (ACL) ruptures. This study attempts to reveal whether there is a relationship between non-contact ACL ruptures and eminential morphometry.

Methods

Knee magnetic resonance images (MRIs) taken for the various indications between January 2022 and June 2023 were retrospectively scanned. The patients were categorized into 2 groups: those with an ACL rupture and those with an intact ACL. For each patient, eminential angle 1, eminential angle 2, medial eminential height, lateral eminential height, total eminential height, eminential width, and the ratio of tibial plateau width and eminential width to the tibial plateau width were measured by 2 different orthopedists. Patients whose MRIs were used for measurement were evaluated and grouped according to their age, sex, and injury side.

Results

In total, 400 MRIs of 400 patients were included in the study. While 200 patients had an ACL rupture, 200 had an intact ACL. The total eminential height in the ACL rupture group was measured at 16.1 ± 2.6 mm and 15.5 ± 2.7 mm (p = 0.035) in the ACL intact group. Eminental width in the ACL rupture group was measured at 12.1 ± 1.9 mm and 13.0 ± 2.0 mm in the ACL intact group (p = 0.0001). The tibial plateau width was 75.4 ± 15.7 mm in the ACL rupture group and 73.6 ± 5.8 mm in the ACL intact group (p = 0.002). According to the logistic regression analysis, the p-value for males was 0.0001, and for eminential width, the p-value was 0.0001.

Conclusions

A significant difference was found between the ACL rupture and the ACL intact groups regarding eminential height, eminential width, and tibial plateau width parameters. Being male and having a low eminential width were identified as independent risk factors for non-contact ACL.

Trial registration

Not applicable.

Background

An anterior cruciate ligament (ACL) rupture is an injury frequently encountered in daily orthopedics practice that is generally associated with sports. Although it has different prevalence rates in Western societies, its prevalence is accepted as 5–8/10.000 [1, 2]. An ACL rupture generally occurs during sports activities after excessive axial loading of the knee at the degrees near full extension with a non-contact mechanism [3] In addition to pain and swelling in the knee and difficulties in further participating in sports-related activities, an ACL rupture can expedite osteoarthritis development in the long term [4].

A large portion of ACL injuries occur with non-contact mechanisms, which shows that identifying the risks leading up to an ACL rupture can help develop protective measures against injury [5]. Extensive research has been conducted based on the belief that the bone morphology characteristics of individuals might be associated with ACL injuries. These studies focused on the morphometric structure of both the distal femur and tibia. Research conducted on the femoral side focuses more on the intercondylar notch [6, 7]. On the other hand, studies focusing on the tibial side mainly deal with the geometrical structure of the tibial plateau and posterior tibial slope [8–11]. The ACL starts from the posterolateral side of the intercondylar notch in the femur; however, in the tibia, it spreads over a larger area, sticks to an area near the tibial eminentia, and remains there. Studies covering the relationship between tibial eminentia and non-contact ACL rupture are less extensive than morphometric studies. Li et al. showed in their study that decreased medial tibial eminence height was associated with ACL injuries [12]. Kuijk et al., in their study on radiographs, showed that small tibial eminence in shape may be associated with ACL injury [13]. Cimen et al. compared the normal knees of the patients with ACL rupture with their knees morphometrically in their study in which they examined bilateral imaging of the same patients; however, they stated that eminential width measurements were not statistically different between the two groups [14]. There are not many studies in the literature evaluating the relationship between ACL rupture and eminential morphometry. However, there are conflicting results in existing studies. For this reason, the researchers aimed to contribute to the literature on this subject.

In light of the available studies in the literature, the authors believe that there is a relationship between non-contact ACL rupture and eminential morphometry.The purpose of this study relationship between eminential morphometry and non-contact ACL ruptures.

Methods

The data scanning process began after obtaining approval from our hospital’s ethics committee for this retrospective and morphometric study. The radiological data of patients over eighteen, who applied to our hospital for knee injuries, and for whom magnetic resonance imaging (MRI) was conducted under appropriate indication were examined. In order to determine the sample size, a pilot study consisting of 40 individuals (20 study, 20 control group) was conducted. In the study, it was determined that the most significant relationship between the measured morphometric parameters and anterior cruciate ligament (ACL) rupture was with eminence width. In the logistic regression analysis, the odds ratio showing the relationship between eminence width and ACL rupture development was found to be 0.7. In the power analysis performed using G*Power 3.1.9.7 software to determine the required sample size, the total sample size required to obtain significant results with a significance level of 5% and a power of 80% was calculated as 395. Knee magnetic resonance images (MRIs) taken for the various indications between January 2022 and June 2023 were retrospectively scanned. Precisely 1,703 knee MRI examinations were identified during the study period. All MRI images were acquired on a GE Signa Pioneer 3T scanner. The inclusion criteria for the study included being in the 18–50 age range, showing clinical (Lachman and anterior drawer test positivity) and radiological findings supporting ACL rupture diagnosis, and presenting appropriate MRI sections to carry out the determined measurements. Exclusion criteria included being younger than 18, patients with contact ACL injuries, having osteoarthritis findings in the knee, having previous arthroscopic or open surgery history on the related extremity, and having a fracture history in the related extremity. Retrospectively scanned MRIs were categorized into 2 groups; one group with ACL Ruptured and one group with ACL Intact. Patients with positive examination findings (anterior drawer test and Lachmann test) but no ACL injury findings on MRI were not included in either group and were not included in the sample. Additionally, patients with ACL partial rupture were not included in the study sample. The inclusion, exclusion, and patient selection criteria for the study are presented in Fig. 1 in more detail.

Fig. 1.

Study flowchart

Radiological measurements

In addition to the measuring methods defined previously in the literature to evaluate the relationship between eminential morphology and non-contact ACL rupture, 2 additional eminential angular measures defined and used in one of our previous studies, which addressed the relationship between adolescent non-contact ACL rupture and morphometric parameters, were utilized in this study. The radiological measurements conducted on patients included in the study and the reference articles of the related measurements are given below:

1. Eminential Height (Medial and Lateral Eminential Height): Eminence height was calculated as the perpendicular distance between the line connecting the lowest parts of the articular surface of both tibial condyles and the highest point of eminentia. Medial, lateral, and overall eminence height were recorded separately [15]. (Fig. 2A)

Fig. 2.

(A) Medial and Lateral Eminential Height Measurement, (B) Eminential Width and Tibia Plateau Width Measurement, (C) Eminential Angle 1 Measurement, (D) Eminential Angle 2 Measurement

• 2.Eminential Width: The highest point of medial eminentia and the highest point of lateral eminentia were determined in the coronal plan. The distance between these 2 peaks was measured, and the eminential width was determined. (Fig. 2B)
• 3.Tibial Plateau Width: Based on the line connecting the medial and lateral plateau joint lines (connecting the lowest parts of the articular surface of both tibial condyles), the tibial plateau surface was determined during coronal MRI. The distance between the specified endpoints was recorded as tibial plateau width.(Fig. 2B).
• 4.Eminential Angle 1: A line was drawn from the peak of the medial eminence to the intereminence area in the coronal plane, and a line was then drawn from the intereminence area to the peak of the lateral eminence. The angle between these 2 lines was recorded as eminence angle 1 [16] (Fig. 2C).
• 5.Eminential Angle 2: The peaks of the medial and lateral eminences were determined in the coronal plane, and a line connecting them was drawn. The angle made by this line and the joint line was recorded as eminence angle 2 [16] (Fig. 2D).

Note

While measurements in the coronal section were made, the highest visible eminences simultaneously of the tibial eminence were measured.

The measurements conducted with MRI stated above are provided in Fig. 2.

All measurements were conducted by 2 different orthopedists with no access to the identity and demographic characteristics of the patients. The average values of the performed measurements were used for the statistical analysis.

Statistical analysis

Statistical analysis was performed using SPSS software (Version 25.0, SPSS Inc., Chicago, IL, USA). If continuous variables were normal, they were described as the mean ± standard deviation (p > 0.05 in Kolmogorov-Smirnov test or Shapira-Wilk (n < 30)), and if the continuous variables were not normal, they were described as the median. The continuous variables were compared by the use of Student t test or Mann-Whitney U test depending on parametric or non-parametric values; respectively. The categorical variables between the groups were analyzed by using the Chi square test or Fisher’s Exact Test.Factors associated with a p value of less than 0.1 in univariate analysis were further evaluated in a multiple logistic regression analysis.The level for statistical significance was predetermined at p < 0.05.

Results

In total, 400 MRIs of 400 patients were included in the study. While 200 of these patients had an ACL rupture, 200 had intact ACL; 151 of the patients with ACL rupture were males, 49 were females, and, in the ACL intact group, 97 of the patients were males and 103 were females(p = 0,0001). While the mean age of the ACL rupture groups was 34.9 ± 9.4, the mean age in the second group was 36.8 ± 9.6 (p = 0.044). Exactly 124 of the knee MRIs of the ACL rupture group were done on the right knee, and 76 were on the left; for the ACL intact group, there were 125 right-knee and 75 left-knee MRIs.

Numerical data of the measurements given in the material and methods section and data on the comparison of the groups are shown in Table 1.

Table 1.

Measurement values of ACL ruptured and ACL intact patients

	ACL Rupture Group (n = 200)		ACL Intact Group (n = 200)		Total
	Mean ± SD	Median (Min-Max)	Mean ± SD	Median (Min-Max)	Mean ± SD	Median (Min-Max)	p
Eminential Angle 2	5,89 ± 4,0	5,6(0–20)	5,5 ± 3,4	5,0(0–16)	5,7 ± 3,7	5,3(0–20)	0,500
Eminential Angle 1	116,1 ± 13,1	115,5(73–149)	116,9 ± 12,0	118(80,7-146)	116,5 ± 12,6	116,9(73–149)	0,506
Medial Eminence Height	8,5 ± 1,5	8,4(4,5–12,2)	8,2 ± 1,3	8,2(5,2–12,5)	8,3 ± 1,4	8,3(4,5–12,5)	0,056
Lateral Eminence Height	7,6 ± 1,4	7,4(4,6–11,0)	7,5 ± 1,5	7,4(4,2–13,0)	7,5 ± 1,4	7,4(4,2–13,0)	0,495
Total Eminence Height	16,1 ± 2,6	16,1(7,4–23,0)	15,5 ± 2,7	15,4(2,7–24,4)	15,8 ± 2,7	15,7(2,7–24,4)	0,035
Eminential Width	12,1 ± 1,9	12,1(7,4–20,7)	13,0 ± 2,0	12,9(8–21)	12,6 ± 2,0	12,5(7,4–21,0)	0,0001
Tibial Plateau Width	75,4 ± 15,7	76,4(62,3–89,7)	73,6 ± 5,8	73(62,5–85,7)	74,5 ± 5,8	75,3(62,3–89,7)	0,002
Eminential/ Plateau Width	0,17 ± 0,07	0,16(0,09 − 0,74)	0,18 ± 0,02	0,18(0,11 − 0,26)	0,17 ± 0,05	0,17(0,09 − 0,74)	0,084

Angle units: Degree Height and width units : milimeter

Table 1. Data on the radiological measurements and intergroup comparison of the ACL rupture and ACL intact groups.

The statistically significant parameters between the groups were evaluated using logistic regression analysis. Being male and having a smaller eminential width were identified as risk factors for an ACL rupture. Data on the logistic regression analysis are given in Table 2.

Table 2.

Data from logistic regression analysis of sex, age, total eminence height, eminential width, tibia plateau width parameters

	B	S.E.	Wald	df	p	Odds Raio	95% C.I.for Odds Raio
							Lower	Upper
Sex	1,54	0,38	16,9	1	0,0001	4,69	2,25	9,82
Age	-0,02	0,01	3,1	1	0,079	0,98	0,95	1,00
Total Eminence Height	0,06	0,05	1,7	1	0,189	1,06	0,97	1,17
Eminential Width	-0,42	0,07	34,9	1	0,0001	0,66	0,57	0,75
Tibial Plateau Width	0,02	0,03	0,01	1	0,940	1,00	0,94	1,07
Constant	3,91	2,10	3,46	1	0,063	50,3

Table 2. Logistic regression analysis data was done using total eminential height, eminential width, and tibial plateau width parameters, which showed a statistically significant difference between the groups.

Discussion

There is scant research showing the relationship between a non-contact ACL rupture and eminential morphometric parameters. This study compared patients with a non-contact ACL rupture with those with an intact ACL according to MRI-based measurements; the total eminential height, eminential width, and tibial plateau width parameters were statistically different between the 2 groups. Being male and having a low eminential width were identified as independent risk factors for a non-contact ACL rupture.

Several studies in the literature have shown that since female athletes are under 4–6 times more at risk of experiencing an ACL rupture, they are an independent risk factor for this type of rupture [17, 18]. This difference may result from anthropometric characteristics, a viewpoint presented in cadaver and clinical studies [19, 20]. It was also revealed that in addition to anthropometric characteristics, biomechanical differences between the 2 sexes can affect the occurrence of sex-related differences in ACL injuries [21, 22]. However, unlike these findings in the literature, the present study shows that being male can be an independent risk factor for an ACL rupture. This difference may have occurred due to ethnic differences between the studied populations because the literature has clearly shown that proximal tibia structures can differ among populations [23]. In light of the current study’s findings and the data in the literature, it is safe to say that sex can result in different effects in different populations in terms of ACL ruptures.

In their research studying 293 male patients, Cimen et al. found that the tibial eminential width was smaller in the ACL rupture group than in the intact group. However, no statistically significant difference was seen between the two [14]. Nevertheless, the authors identified a statistically significant difference between the groups in terms of tibial plateau width and the ratio of eminential width/tibial plateau width, concluding that the anatomical structure of the proximal tibia might affect the widening of the ACL rupture. When we examined studies focusing on the relationship between eminential morphology and ACL ruptures, eminential width was higher in patients with intact ACL [24, 25]. Van Kuijk et al. used the Rosenberg graphics and the lateral graphs of 168 patients to reveal the relationship between the radiographic shape of the knee and ACL ruptures. The authors concluded that a smaller tibial eminentia could be a risk factor for an ACL rupture [13] Bayer et al., in their systematic review examining knee morphometric parameters, which could be a risk factor for an ACL rupture, found that a reduced tibial eminence size was a risk factor [26]. Misir et al., on the other hand, in their study examining 352 male patients, studied the relationship between ACL ruptures and eminential width, tibial plateau width, and eminentia width index but could not find any statistically significant relationship between these 3 factors and ACL rupture [27] Sturnick et al. included the MRIs of the intact contralateral knee of 88 patients and observed the differences between the 2 groups in terms of eminential morphology [10] The results showed that while a decreased volume of the medial tibial eminentia could pose a risk in males, the same decrease did not pose any risks for an ACL rupture in females [10] However, our study, which evaluated the relationship between eminential morphology and ACL ruptures through measurements effectuated on 200 patients with ruptures and 200 patients with intact ACLs, demonstrated that a significant relationship exists between ACL ruptures and eminential height, eminential width, and tibia plaeau width. There are different data sets and views in the literature about the effect of eminential and proximal tibia morphometric structures on non-contact ACL ruptures. In these studies, the main differences are those in the morphometric structure of the knee in different individuals and populations. Even though related studies have reached different conclusions, fundamentally, the relationship between eminentia and proximal tibia morphometry and non-contact ACL rupture has been established. Because of its similar results, our study also contributes to previous research findings.

Since there is an inadequate number of parameters for the evaluation of eminential morphometry in the literature, the authors of this study utilized 2 different eminential angles, defined in previous research, which studied adolescent ACL ruptures and morphometric parameters. While eminential angle 1 was lower in the ACL rupture group than in the ACL intact group, eminential angle 2 was higher in the ACL rupture group. However, no statistically significant difference was found between these groups in terms of these 2 parameters. Because it is an angular measure and can contribute to defining eminential morphometry in 2-dimensional measurements, comparative studies with higher participation rates and studies that determine validation and cut-off values in different populations can be conducted in the future.

Considering the impact of this study on clinical studies; the data obtained at the end of the study can be used to identify patients at high risk of ACL rupture. Again, in the light of this data, professional athletes can be determined as risky by performing morphometric analyses and more importance can be given to injury prevention programs. In other words, morphometric-based studies can be used to determine the risk status of individuals in terms of ACL rupture. Kuijk [13] and colleagues also made similar clinical recommendations in their study. Clinical and biomechanical studies are needed to understand the impact of these data on current ACL surgery procedures.

This study has some limitations. The study’s retrospective design and the fact that only a specific population was measured affected the generalizability of the study. The gold standard for the diagnosis of ACL rupture is arthroscopic imaging, but this study used diagnostic information from MRI and physical examination findings.In addition, not utilizing any computer or artificial intelligence (AI)-aided measurement techniques may have increased the human-related error margin.

Conclusion

Compared with the ACL intact group, the ACL rupture group had a higher total eminential height and tibial plateau width but a lower eminential width. The differences in these parameters were found to be statistically significant. Being male and having a low eminential width were identified as independent risk factors for non-contact ACL ruptures.

Abbreviations

ACL

Anterior Cruciate Ligament

MRI

Magnetic Resonance Imagining

Author contributions

SA Manuscript writing/editing, protocol and project development, AK Data collection, CC Data collection and Data Analysis, MU Manuscript writing/editing, MD Manuscript writing/editing.

Funding

No Funding.

Data availability

The datasets used during the current study are available from the corresponding author (SA) on reasonable request and after ethical permission.

Declarations

Ethical approval

We confirm that all experiments were performed in accordance with the Declaration of Helsinki. The study was approved by the Ethical Committee of Ankara City Hospital Clinical Ethics Committee, NO. E1-23-4467. Each patient provided written informed consent before participating in the study.

Consent for publication

All authors accept that.

Competing interests

The authors declare no competing interests.