Abstract
Background
Kaplan fibers (KFs) are critical stabilizers of the knee, yet their role in anterior tibial subluxation of the lateral compartment (ATSLC) in anterior cruciate ligament (ACL) injury remains unclear. This study is to determine whether KF injury is independently associated with increased ATSLC on magnetic resonance imaging (MRI) in patients with an injured ACL, and to identify risk factors for high-grade ATSLC (≥ 4.5 mm).
Patients and methods
This retrospective study enrolled 132 patients with ACL injury who underwent MRI within 12 weeks of trauma. MRI was used to evaluate the integrity of the ACL, KFs, anterolateral ligament (ALL), bony morphology, and ATSLC. Two trained observers independently assessed all images using standardized criteria. Agreement between observers was calculated using standard reliability metrics. Multivariable linear regression was performed to evaluate the independent association between KF injury and ATSLC. Logistic regression and receiver operating characteristic analysis were used to identify predictors of high-grade anterior tibial subluxation (≥ 4.5 mm) in patients with combined ACL and anterolateral complex injuries.
Results
Of the 132 patients, 35.6% had KF injuries. These patients exhibited higher rates of ALL injury and distinct bony morphologic features. KF injury independently explained 15.1% of anterior tibial subluxation variability (P < 0.001). In patients with combined anterolateral complex injuries, increased lateral femoral condyle width ratio was identified as an independent predictor of high-grade subluxation.
Data conclusion
KF injury is independently associated with greater anterior tibial subluxation, suggesting a key role in post-traumatic knee instability. Specific femoral anatomical feature may further predict high-risk cases.
Level of evidence
Level IV.
Keywords: Anterior cruciate ligament, Kaplan fibers, Anterolateral ligament, Morphological parameters, Anterior tibial subluxation of the lateral compartment
Introduction
Anterior cruciate ligament (ACL) injury is one of the most prevalent sports-related knee injuries, with a rising global incidence [1, 2]. It significantly compromises joint stability and predisposes patients to cartilage degeneration and post-traumatic osteoarthritis [3, 4]. Although anterior cruciate ligament reconstruction (ACLR) is the standard treatment, many patients suffer from graft failure, particularly in cases with anterolateral rotatory instability (ALRI), where isolated ACLR may be insufficient [5–7]. This highlights the importance of the anterolateral stabilizers of the knee.
The anterolateral complex (ALC) of the knee consists of the superficial and deep layers of the iliotibial band, including the Kaplan fibers (KFs), as well as the iliopatellar band, anterolateral ligament (ALL), and joint capsule [8]. As secondary stabilizers of the ACL, these structures play a vital role in resisting internal tibial rotation during knee flexion. Moreover, biomechanical evidence suggests that KFs contribute more to rotational restraint than the ALL, especially at flexion angles beyond 30° [6, 9].
In recent years, magnetic resonance imaging (MRI) has enabled reliable visualization of KFs, with identification rates ranging from 93.4% to 100% using standard imaging sequences [10–12]. Despite evolving diagnostic criteria, KF injuries have been reported in 6–61% of ACL-injured knees, suggesting they may be more frequently affected than previously recognized [11, 13]. However, the clinical implications of KF injury, especially its potential independent contributions to knee instability, remain underexplored.
Anterior tibial subluxation of the lateral compartment (ATSLC), measured on MRI, has emerged as a promising static imaging marker of knee instability following ACL injury. An increased ATSLC is closely associated with higher degrees of rotatory instability and may persist even after ACLR, negatively affecting surgical outcomes [14–16]. While prior studies have identified ALL and lateral meniscus posterior root injuries as independent contributors to elevated ATSLC [17, 18], the specific role of KF injury in this context has yet to be clearly defined. Considering the biomechanical role of KFs in controlling internal rotation, it is reasonable to hypothesize that damage to these structures may contribute to abnormal tibiofemoral relationship.
Therefore, the present study was designed to investigate whether KF injury is independently associated with increased ATSLC in patients with an injured ACL, and to identify risk factors for high-grade ATSLC (≥ 4.5 mm) in those with combined ACL and ALC injuries.
Patients and methods
Patient selection
This retrospective study included patients with an injured ACL who underwent primary ACLR at a single medical center between January 2020 and December 2023. Inclusion criteria were: (1) age 14–55 years, (2) MRI performed within 12 weeks post-injury at our institution, (3) MRI-confirmed partial or complete ACL injury, (4) complete clinical data, and (5) arthroscopically confirmed ACL injury. Patients were excluded if they had any of the following: (1) prior fractures or ligament injuries (n = 48), (2) joint infection (n = 2), (3) previous surgery (n = 19), (4) MRI evidence of tears involving the popliteus tendon (PT), biceps femoris tendon (BFT), or popliteofibular ligament (PFL) (n = 28), or (5) inadequate MRI image quality (n = 121). After applying these criteria, a total of 132 patients were included in the final analysis. The study was approved by the institutional ethics board, and informed consent was obtained from all participants.
Baseline data collection
Baseline clinical variables included age, sex, side of injury, and the time interval from injury to MRI evaluation.
MRI evaluation and measurements
MRI examinations were performed on 3.0-T (Verio, Siemens Healthineers) or 1.5-T (Aera, Siemens Healthineers) scanners following a standardized institutional protocol, which included sagittal T1-weighted sequences and proton-density-weighted sequences in coronal, sagittal, and axial planes. Imaging parameters were at or close to the following ranges: repetition time (TR), 500–3500 ms; echo time (TE), 19–39 ms; field of view, 15–18 cm; slice thickness, 3.0–4.0 mm with an interslice gap of 0.3–1.2 mm; and number of excitations, 1. Parallel imaging was applied when available (acceleration factor up to 2). Typical acquisitions consisted of 23–25 slices. Patients were positioned supine with the knee relaxed in a natural flexion of 10–15°, and secured in a dedicated knee coil.
A musculoskeletal radiologist and an orthopedic surgeon (Z.Z. and P.B., 6 years and 3 years of experience) independently evaluated all images, blinded to clinical information. Both had prior training to standardize assessment of structures such as KFs and ALL. In cases of disagreement, a senior radiologist (L.B., 32 years of experience) conducted an independent review after 2 weeks.
ACL status was categorized as partial or complete rupture. Meniscal injuries and collateral ligaments injuries were recorded by location, as were associated injuries of the posterior cruciate ligament (PCL). The status of the KFs was evaluated according to the diagnostic criteria proposed by Batty et al. [19], with the same the threshold applied for images obtained from both 1.5-T and 3.0-T scanners. As summarized in Table 1, KF injury was diagnosed if ≥ 1 direct sign or ≥ 2 indirect signs appeared on any plane. Representative MRI findings of KF injury are shown in Fig. 1. ALL injury was defined per Helito et al. [20] as fiber discontinuity or surrounding edema with irregular contour. Representative MRI appearances of normal and injured ALL are shown in Fig. 2.
Table 1.
MRI diagnostic criteria for KF injury (Batty et al. [19])
| Sign of injury | Criteria |
|---|---|
| Direct sign | Discontinuity of the KFs |
| Femoral avulsion of the KFs | |
| Indirect sign | Thickening and/or intrasubstance signal change of the KFs |
| Focal bone marrow edema at KFs insertion site to the femur | |
| Soft tissue edema in region of KFs | |
| Wavy appearance to the KFs |
MRI, magnetic resonance imaging; KFs, Kaplan fibers
Fig. 1.
MRI signs of Kaplan fiber (KF) injury. a KFs discontinuity with pericapsular edema (white arrow). b Signal alteration of the KFs (white arrow). c Bone marrow edema at the femoral insertion of the KFs (white arrow). d A wavy contour of the KFs (yellow arrow)
Fig. 2.
MRI findings of normal and injured anterolateral ligament (ALL). a A normal ALL (white arrow). b An injured ALL showing periligamentous edema and an irregular contour (yellow arrow)
Bony morphological parameters were measured on MRI following methods described previously [17, 21]. Specifically, lateral femoral condyle (LFC) depth and height were measured on sagittal images at the most medial tibiofibular joint; the LFC width ratio was calculated as the LFC width divided by the total bicondylar width; lateral tibial plateau (LTP) depth and lateral tibial slope (LTS) were also measured on corresponding sagittal images (Figs. 3 and 4).
Fig. 3.
Measurements of morphological parameters of the lateral femoral condyle (LFC) and lateral tibial plateau (LTP). a At the most medial tibiofemoral compartment, a line perpendicular to the femoral shaft axis intersects the anterior and posterior cortices of the LFC; the length of the yellow line from the intersection to the posterior cortex represents the LFC depth. b A best-fit circle tangent to the posterior cortex of the LFC (white circle); the diameter of the yellow line denotes the LFC height. c At the level of the widest femoral condyles, yellow line (medial/lateral condyle) indicates total condylar width; yellow diameter of the white circle represents the LFC width. LFC width ratio = LFC width/total condylar width. d At the most medial tibiofemoral compartment, two white lines (parallel to femoral shaft axis, tangent to tibial plateau anterior/posterior cortices) define LTP depth as yellow line length between them
Fig. 4.
Measurement of lateral tibial slope (LTS) and anterior tibial subluxation of the lateral compartment (ATSLC). a At the most medial tibiofemoral compartment, the angle between the lateral tibial plateau (LTP) tangent and a line perpendicular to the tibial shaft axis is defined as the LTS. b At the same compartment, a best-fit circle aligned to the posterior cortex of the lateral femoral condyle; two LTP tangent-perpendicular lines (LTP posterior edge/circle tangent); the red line connecting these two lines represents the ATSLC distance
ATSLC was measured according to the method described by McDonald et al. [22]. Iwaki et al. initially described this electronic measurement technique on cadaveric knee specimens and validated the accuracy of MRI as a tool for measuring knee kinematic parameters [23]. Later, Tanaka et al. began using this MRI technique to assess the static tibiofemoral relationship [24]. Results obtained using this method have demonstrated excellent inter- and intra-observer reliability in several studies [14, 16, 18]. To ensure consistency in the lateral compartment, measurements were taken using standard reference points for each compartment. On sagittal slices at the most medial aspect of the tibiofibular joint, the distance between the LTP and the LFC was recorded. Positive values indicated anterior subluxation, while negative values indicated posterior displacement. Measurement precision was set at 0.01 mm (Fig. 4b).
Statistical analysis
All statistical analyses were performed using SPSS software (version 25.0; IBM Corp., Armonk, NY, USA). Normality of continuous variables was assessed using the Shapiro–Wilk test. Normally distributed data were expressed as mean ± standard deviation and compared using independent-samples t-tests; non-normally distributed data were presented as median (interquartile range) and analyzed using the Mann–Whitney U test. Categorical variables were reported as counts (percentages) and compared using the chi-square test or Fisher’s exact test, as appropriate. Ordinal variables were analyzed using the Mann–Whitney U test.
A multivariable linear regression model was used to examine the association between KF injury and ATSLC. Prior studies have shown that meniscal injury and ALL injury are associated with anterolateral tibial subluxation [17, 18], suggesting that these structural injuries and anatomic variations may confound the association of our interest. To account for potential confounding factors, selected variables were entered into the regression model in a hierarchical fashion. The change in R2 and significance of variables across models were calculated to evaluate the independent contribution of KF injury to ATSLC.
Potential risk factors for high-grade ATSLC (≥ 4.5 mm) were identified through univariate analysis followed by multivariable logistic regression (P < 0.20 for entry). Odds ratios (OR), 95% confidence intervals (CI), and P-values are reported. Model performance was evaluated using receiver operating characteristic (ROC) analysis, including area under the curve (AUC), optimal cutoff (Youden index), and corresponding sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV). AUC values were interpreted according to Mandrekar’s criteria [25]. Multicollinearity was assessed using variance inflation factors (VIFs), with VIFs < 10 indicating no concern. A two-sided P-value ≤ 0.05 was considered statistically significant.
Interobserver agreement for KFs and anterolateral ligament assessments was assessed using Cohen’s kappa according to established guidelines [26]. Measurement reliability for continuous variables was evaluated using intraclass correlation coefficients (ICC) following recommended standards [27].
Results
Baseline characteristics
A total of 132 patients with ACL injury were enrolled, including 96 men and 36 women, with an average age of 31.1 ± 10.7 years. Left knee injuries were observed in 79 patients, and right knee injuries in 53 patients. The time interval from injury to MRI evaluation was 3.9 ± 3.9 weeks on average. Fifteen patients had partial ACL injuries, while 117 had complete ACL ruptures.
KF injuries were identified in 47 patients (35.6%). Based on KF status, patients were categorized into an ACL + KF injury group and an ACL-only injury group. As summarized in Table 2, no significant differences were found between the two groups in sex (P = 0.119), age (P = 0.497), side of injury (P = 0.676), time interval from injury to MRI evaluation (P = 0.277), or severity of ACL injury (P = 0.292).
Table 2.
Comparison of baseline characteristics between patients with ACL + KF injury and patients with ACL-only injury
| Baseline characteristics | ACL + KF injury (n = 47) |
ACL-only injury (n = 85) |
P value |
|---|---|---|---|
| Sex | 0.119 | ||
| Male | 38 (80.9) | 58 (68.2) | |
| Female | 9 (19.1) | 27 (31.8) | |
| Age (years) | 31.8 ± 8.6 | 30.6 ± 11.7 | 0.497 |
| Side of injury | 0.676 | ||
| Left | 27 (57.4) | 52 (61.2) | |
| Right | 20 (42.6) | 33 (38.8) | |
| Time from injury to MRI (weeks) | 3.4 ± 3.5 | 4.2 ± 4.1 | 0.277 |
| Severity of ACL injury | 0.292 | ||
| Partial injury | 3 (6.4) | 12 (14.1) | |
| Complete injury | 44 (93.6) | 73 (85.9) |
Data are presented as n (%) or mean ± SD. ACL, anterior cruciate ligament; KF, Kaplan fiber; MRI, magnetic resonance imaging
MRI measurement reliability
The interobserver agreement for identifying KFs and ALL on MRI was substantial. Quantitative measurements of bone morphology and joint alignment parameters demonstrated excellent interobserver reliability, as reflected by high ICCs. Detailed reliability metrics are presented in Table 3.
Table 3.
Interobserver reliability of MRI measurement
| MRI measurement | Cohen’s kappa | ICC |
|---|---|---|
| KFs | 0.702 | – |
| ALL | 0.755 | – |
| LFC depth | – | 0.908 |
| LFC height | – | 0.923 |
| LFC width ratio | – | 0.920 |
| LTP depth | – | 0.943 |
| LTS | – | 0.871 |
| ATSLC | – | 0.918 |
MRI, magnetic resonance imaging; ICC, intraclass correlation coefficients; KFs, Kaplan fibers; ALL, anterolateral ligament; LFC, lateral femoral condyle; LTP, lateral tibial plateau; LTS, lateral tibial slope; ATSLC, anterior tibial subluxation of the lateral compartment
Concomitant structural injury comparison
There were no statistically significant differences between the two groups in the incidence of concomitant PCL injuries. Similarly, no significant differences were observed between the groups regarding the incidence and location of medial and lateral meniscus injuries, or the incidence of collateral ligament injuries (Table 4).
Table 4.
Comparison of concomitant structural injury between patients with ACL + KF injury and patients with ACL-only injury
| Concomitant structural injury | ACL + KF injury (n = 47) |
ACL-only injury (n = 85) |
P value |
|---|---|---|---|
| PCL injury | 14 (29.8) | 17 (20.0) | 0.204 |
| Meniscus injury | |||
| MM injury | 30 (63.8) | 52 (61.2) | 0.763 |
| LM injury | 29 (61.7) | 44 (51.8) | 0.272 |
| MM injury | |||
| MMAH injury | 7 (14.9) | 7 (8.2) | 0.234 |
| MMB injury | 9 (19.1) | 16 (18.8) | 0.906 |
| MMPH injury | 30 (63.8) | 49 (57.6) | 0.488 |
| LM injury | |||
| LMAH injury | 16 (34.0) | 24 (28.2) | 0.487 |
| LMB injury | 8 (17.0) | 17 (20.0) | 0.676 |
| LMPH injury | 23 (48.9) | 33 (38.8) | 0.260 |
| Collateral ligament injury | |||
| MCL injury | 17 (36.2) | 29 (34.1) | 0.813 |
| LCL injury | 15 (31.9) | 20 (23.5) | 0.296 |
| ALL injury* | 38 (80.9) | 51 (60.0) | 0.014 |
Data presented as n (%). ACL, anterior cruciate ligament; KF, Kaplan fiber; PCL, posterior cruciate ligament; MM, medial meniscus; LM, lateral meniscus; MMAH, medial meniscus anterior horn; MMB, medial meniscus body; MMPH, medial meniscus posterior horn; LMAH, lateral meniscus anterior horn; LMB, lateral meniscus body; LMPH, lateral meniscus posterior horn; MCL, medial collateral ligament; LCL, lateral collateral ligament; ALL, anterolateral ligament. * Variable shows a statistically significant P value; the corresponding P value is bolded
However, the ACL + KF injury group had a significantly higher rate of ALL injury compared with the ACL-only injury group (80.9% versus 60.0%, P = 0.014) (Table 4).
Morphological parameters comparison
The ACL + KF injury group demonstrated significantly greater LFC depth (P = 0.011), height (P = 0.010), and width ratio (P = 0.001) compared with the ACL-only injury group. No significant differences were found between the two groups in terms of LTP depth (P = 0.308) or LTS (P = 0.080). The detailed results are summarized in Table 5.
Table 5.
Comparison of morphological parameters between patients with ACL + KF injury and patients with ACL-only injury
| Morphological parameters | ACL + KF injury (n = 47) |
ACL-only injury (n = 85) |
P value |
|---|---|---|---|
| LFC depth (mm)* | 39.8 ± 3.2 | 38.3 ± 3.4 | 0.011 |
| LFC height (mm)* | 36.8 ± 3.2 | 35.2 ± 3.4 | 0.010 |
| LFC width ratio (%)* | 29.8 ± 2.2 | 28.6 ± 1.9 | 0.001 |
| LTP depth (mm) | 47.9 ± 4.9 | 47.0 ± 4.8 | 0.308 |
| LTS (°) | 8.8 ± 3.3 | 7.8 ± 3.1 | 0.080 |
Data presented as mean ± SD. ACL, anterior cruciate ligament; KF, Kaplan fiber; LFC, lateral femoral condyle; LTP, lateral tibial plateau; LTS, lateral tibial slope. * Variable shows a statistically significant P value; the corresponding P value is bolded
Association between KF status and ATSLC
Hierarchical linear regression analysis showed that model 1 (confounders only) explained 24.6% of ATSLC variance (R2 = 0.246, P < 0.001). Adding KF injury (model 2) increased the R2 to 0.397, reflecting an additional 15.1% variance explained. KF injury was associated with a mean ATSLC increase of 3.367 mm (95% CI 2.124–4.611, P < 0.001). The time interval from injury to MRI (P = 0.012) and a smaller LTP depth (P = 0.031) were also identified as significant predictors. After adjusting for KF injury, variables such as ALL injury and LFC width ratio were no longer significant. Detailed results are summarized in Table 6.
Table 6.
Multiple linear regression analysis of ATSLC in patients with ACL injury
| Model 1 | Model 2 | |||||||
|---|---|---|---|---|---|---|---|---|
| β | 95% CI | P Value | R2 | β | 95% CI | P Value | R2 | |
| Model | 0.003 | 0.246 | < 0.001 | 0.397 | ||||
| Male | 1.506 | −0.376 to 3.389 | 0.116 | 1.403 | −0.288 to 3.094 | 0.103 | ||
| Age | 0.026 | −0.039 to 0.090 | 0.435 | 0.003 | −0.056 to 0.062 | 0.920 | ||
| Time from injury to MRI* | 0.171 | 0.007 to 0.335 | 0.041 | 0.189 | 0.042 to 0.337 | 0.012 | ||
| Complete ACL injury | 1.581 | −0.304 to 3.465 | 0.099 | 1.294 | −0.402 to 2.990 | 0.134 | ||
| PCL injury | 1.161 | −0.280 to 2.603 | 0.113 | 0.851 | −0.448 to 2.151 | 0.197 | ||
| MM injury | −0.245 | −1.509 to 1.018 | 0.701 | −0.048 | −1.185 to 1.089 | 0.934 | ||
| LM injury | 0.604 | −0.590 to 1.799 | 0.318 | 0.242 | −0.839 to 1.323 | 0.658 | ||
| MCL injury | 0.369 | −1.078 to 1.815 | 0.614 | 0.649 | −0.654 to 1.953 | 0.326 | ||
| LCL injury | −0.897 | −2.376 to 0.581 | 0.232 | −1.059 | −2.389 to 0.271 | 0.117 | ||
| LFC depth | 0.123 | −0.210 to 0.457 | 0.466 | 0.089 | −0.211 to 0.389 | 0.557 | ||
| LFC height | 0.215 | −0.179 to 0.609 | 0.281 | 0.074 | −0.283 to 0.431 | 0.682 | ||
| LFC width ratio* | 0.336 | 0.047 to 0.624 | 0.023 | 0.092 | −0.183 to 0.366 | 0.510 | ||
| LTP depth* | −0.257 | −0.446 to −0.068 | 0.008 | −0.189 | −0.361 to −0.017 | 0.031 | ||
| LTS | 0.151 | −0.042 to 0.343 | 0.124 | 0.083 | −0.091 to 0.258 | 0.346 | ||
| ALL injury* | 1.418 | 0.133 to 2.704 | 0.031 | 0.795 | −0.383 to 1.972 | 0.184 | ||
| KF injury* | – | – | – | 3.367 | 2.124 to 4.611 | < 0.001 | ||
β, the regression coefficient; 95% CI, 95% confidence interval; R2, coefficient of determination. ATSLC, anterior tibial subluxation of the lateral compartment, ACL, anterior cruciate ligament; MRI, magnetic resonance imaging; PCL, posterior cruciate ligament; MM, medial meniscus; LM, lateral meniscus; MCL, medial collateral ligament; LCL, lateral collateral ligament; LFC, lateral femoral condyle; LTP, lateral tibial plateau; LTS, lateral tibial slope; ALL, anterolateral ligament; KF, Kaplan fiber. *Variable shows a statistically significant P value; the corresponding P value is bolded
Risk factors for high-grade ATSLC in ACL + ALC injury patients
Given the close relationship between KF and ALL injuries, patients with either lesion were classified as ACL + ALC injury (n = 98). These patients were further stratified into a high-grade ATSLC group (ATSLC ≥ 4.5 mm, n = 44) and a low-grade ATSLC group (ATSLC < 4.5 mm, n = 54) for subsequent analyses.
Univariate analysis identified sex (P = 0.111), medial collateral ligament (MCL) injury (P = 0.111), LFC width ratio (P = 0.008), and LTS (P = 0.067) as candidate variables (Table 7). Multivariable regression analysis showed that LFC width ratio (OR = 1.281; 95% CI 1.035–1.585; P = 0.023) was the only independent risk factor. Each 1% increase in LFC width ratio raised the risk of high-grade ATSLC by 28.1% (Table 8).
Table 7.
Univariate analysis between high-grade ATSLC group and low-grade ATSLC group in patients with ACL + ALC injury
| Variable | High-grade ATSLC (n = 44) |
Low-grade ATSLC (n = 54) |
P value |
|---|---|---|---|
| Sex* | 0.111 | ||
| Male | 37 (84.1) | 38 (70.4) | |
| Female | 7 (15.9) | 16 (29.6) | |
| Age (years) | 30.8 ± 9.1 | 31.9 ± 11.1 | 0.684 |
| Time from injury to MRI (weeks) | 3.2 ± 3.5 | 3.8 ± 3.7 | 0.339 |
| Complete ACL injury | 41 (93.2) | 48 (88.9) | 0.704 |
| PCL injury | 13 (29.5) | 11 (20.4) | 0.293 |
| Meniscus injury | |||
| MM injury | 28 (63.6) | 37 (68.5) | 0.611 |
| LM injury | 25 (56.8) | 29 (53.7) | 0.758 |
| Collateral ligament injury | |||
| MCL injury* | 19 (43.2) | 15 (27.8) | 0.111 |
| LCL injury | 15 (34.1) | 14 (25.9) | 0.378 |
| LFC depth (mm) | 39.4 ± 3.1 | 39.0 ± 3.8 | 0.663 |
| LFC height (mm) | 36.5 ± 3.1 | 35.9 ± 3.5 | 0.358 |
| LFC width ratio (%)* | 29.6 ± 1.9 | 28.5 ± 2.3 | 0.008 |
| LTP depth (mm) | 47.6 ± 4.7 | 47.9 ± 4.7 | 0.740 |
| LTS (°)* | 9.2 ± 3.1 | 8.0 ± 3.3 | 0.067 |
Data presented as n (%) or mean ± SD. ATSLC, anterior tibial subluxation of the lateral compartment; ACL, anterior cruciate ligament; ALC, anterolateral complex; MRI, magnetic resonance imaging; PCL, posterior cruciate ligament; MM, medial meniscus; LM, lateral meniscus; MCL, medial collateral ligament; LCL, lateral collateral ligament; LFC, lateral femoral condyle; LTP, lateral tibial plateau; LTS, lateral tibial slope. High-grade ATSLC, ATSLC ≥ 4.5 mm; low-grade ATSLC, ATSLC < 4.5 mm. *Variable shows a P value < 0.20; the corresponding P value is bolded
Table 8.
Logistic regression analysis for ATSLC grade in patients with ACL + ALC injury
| Variable | β | SE (β) | OR (95% CI) | p value |
|---|---|---|---|---|
| Intercept | −9.312 | 3.298 | – | – |
| Male | 0.882 | 0.561 | 2.415 (0.804–7.260) | 0.116 |
| MCL injury | 0.566 | 0.470 | 1.761 (0.701–4.425) | 0.228 |
| LFC width ratio* | 0.247 | 0.109 | 1.281 (1.035–1.585) | 0.023 |
| LTS | 0.121 | 0.070 | 1.129 (0.984–1.294) | 0.084 |
ATSLC grade was the dependent variable (1 = high-grade, 0 = low-grade). β, regression coefficient; SE, standard error; OR, odds ratio; 95% CI, 95% confidence interval. ATSLC, anterior tibial subluxation of the lateral compartment, ACL, anterior cruciate ligament; ALC, anterolateral complex; MCL, medial collateral ligament; LFC, lateral femoral condyle. *Variable shows a statistically significant P value; the corresponding P value is bolded
ROC analysis showed that the overall model had acceptable discrimination (AUC = 0.710), while the LFC width ratio had lower predictive ability (AUC = 0.651). Optimal cutoff was 27.5% for LFC width ratio (0.932 sensitivity, 0.885 NPV), but specificity and PPV were low (Table 9; Fig. 5).
Table 9.
Diagnostic value of significant predictors and overall model performance for high-grade ATSLC
| AUC | AUC (95% CI) |
Cutoff | Sensitivity | Specificity | PPV | NPV | |
|---|---|---|---|---|---|---|---|
| Model | 0.710 | 0.607–0.814 | 0.459 | 0.705 | 0.722 | 0.674 | 0.750 |
| LFC width ratio | 0.651 | 0.543–0.759 | 27.467 | 0.932 | 0.426 | 0.569 | 0.885 |
AUC, area under the curve; 95% CI, 95% confidence interval; PPV, positive predictive value; NPV, negative predictive value. ATSLC, anterior tibial subluxation of the lateral compartment, LFC, lateral femoral condyle. High-grade ATSLC, ATSLC ≥ 4.5 mm
Fig. 5.
Receiver operating characteristic (ROC) curves of the overall model and lateral femoral condyle (LFC)
Discussion
MRI remains the primary noninvasive tool for evaluating anterolateral structures, and thus its diagnostic accuracy and reliability are critical. A study has shown that routine MRI has been reported to detect ALL injury with high sensitivity and specificity (88% and 100%, respectively) [28], and Berthold et al. confirmed the accurate detection of KF injuries on MRI in a cadaveric study [29]. However, other available evidence remains limited. In this study, KF and ALL injuries were evaluated using standardized diagnostic criteria, which have demonstrated excellent interobserver agreement in previous studies as well as in our cohort [19, 20], supporting the reliability of our evaluation of anterolateral structures injuries.
Prior study has demonstrated that KFs can be reliably identified on routine MRI, with no significant difference in injury detection rates between 1.5-T and 3.0-T images when using the same criteria [11]. And the interval from injury to MRI has been recognized as an important factor affecting diagnosis of anterolateral structure injuries [30, 31]. Previous studies have suggested that the detection rate of KF and ALL injuries may decrease as the time from injury increases, possibly owing to varying degrees of healing [12, 32]. To maintain adequate diagnostic sensitivity and reduce heterogeneity, only patients who underwent MRI within 12 weeks after injury were included in the present study, which is consistent with prior studies of anterolateral structure injuries [11, 33]. Moreover, baseline comparisons showed no significant difference in the injury to MRI interval between patients with and without KF injury, suggesting that the potential influence of this factor on the reliability of our findings may be limited.
We found no significant associations between KF injury and PCL, meniscal, or collateral ligament injuries. Previous studies have reported varying results, highlighting the complex injury mechanisms of the knee. Batty et al. and Devitt et al. respectively found a higher incidence of lateral meniscal injury in patients with combined KF injury [19, 34]. In our study, although patients with combined KF injury had higher rates of lateral meniscus and its anterior and posterior horn injuries, no statistical significance was observed, consistent with the findings of Lynch et al. and Watanabe et al. [11, 35] Balendra et al. reported a correlation between KF injury and MCL injury [36], while another study revealed that KF injury is associated with increased risk of both MCL and lateral collateral ligament (LCL) injuries [19]. Although our study also showed a similar trend, it did not reach statistical significance. However, our finding of a higher ALL injury rate in the ACL + KF group reinforces the close anatomical and functional relationship within the ALC, consistent with ALL’s recognized role in anterolateral stability [37–39].
Prior studies have linked similar morphological features to ACL injury risk and reconstruction outcomes, suggesting altered tibiofemoral kinematics and increased rotational laxity as potential mechanisms [40–42]. On the basis of MRI measurements, our study suggests that larger LFC depth, height, and width ratios may be associated with a higher risk of KF injury. However, given the limited research on the correlation between bone morphology and KF injury, this relationship lacks biomechanical evidence for support. While previous studies have proposed that femoral condyle depth may be linked to altered loading patterns of anterolateral structures such as the ALL [43], further high-quality cadaveric studies are needed to validate the potential mechanisms underlying KF injury patterns.
The key finding of this study is that KF injury is an independent risk factor for increased ATSLC in patients with an injured ACL, accounting for 15.1% of ATSLC variability. While cadaveric studies show that KFs provide stronger restraint against tibial rotation than the ALL [6, 44], their complete transection models may not reflect clinical KF injury patterns. By using ATSLC as a static MRI marker of rotational instability, our study provides in vivo imaging evidence of the association between KF injury and knee instability. Recent studies support this association: KF injury has been linked to greater tibial rotation and high-grade pivot shift in ACL-deficient patients [38, 45].
Importantly, after adjusting for KF injury, the association between ALL injury and ATSLC disappeared, suggesting that KFs may be the dominant contributor to ALC-related instability. Notably, prior studies linking ALL injury to ATSLC did not account for KF injury [17]. Accordingly, we analyzed KFs and ALL as a combined ALC injury to better capture their collective role.
Since posterior–lateral structures (PLS) injury is commonly observed in the ACL-injured population and is considered to play a significant role in knee instability [46–48], we aimed to minimize the potential confounding effect of these structures on our causal inference of ATSLC. After excluding PT, BFT, and PFL injuries, we included LCL injury, another component of PLS, as a confounder in the ATSLC regression model. The results indicated that, even after accounting for LCL injury, the correlation between KF injury and ATSLC remained significant. Moreover, in our model, longer time from injury to MRI was significantly associated with increased ATSLC, consistent with findings from previous studies [49]. Although our study suggests a potential relationship between LTP depth and ATSLC, the supporting evidence remains limited.
We found that greater LFC width ratio emerged as an independent predictor of high-grade ATSLC in ACL + ALC injuries, indicating potential anatomical correlates of knee instability. LFC morphology may alter tibiofemoral kinematics and contribute to increased pivot shift [50]. Zheng et al. found that increased LFC depth and decreased LFC height are associated with a higher risk of ATSLC [17]. However, research on the relationship between LFC width and knee stability remains limited. In addition, the cutoff value of the LFC width ratio (27.5%) was calculated using the Youden index. Although this threshold demonstrated promising sensitivity (0.932) and negative predictive value (0.885) in our cohort, the limited specificity and predictive performance indicate that this threshold may lead to a higher risk of overdiagnosis. Therefore, it should be interpreted with caution. More importantly, this threshold should be regarded as an exploratory result for high-grade ATSLC risk factors, as it has not been validated in any external cohorts and thus cannot provide reference value for clinical practice. Future studies still need to verify the reliability of this threshold in larger and more diverse cohorts. Moreover, while the relationship between LTS and knee injury has been widely reported [51–53], Song et al. also identified increased tibial slope as an independent risk factor for ATSLC > 6 mm [54]. In our multivariable model, the impact of LTS on high-grade ATSLC was not statistically significant.
This study has several limitations. (1) All MRI data were obtained at a single center using an institution scanning protocol. Although this protocol reflects routine clinical practice, differences in sequence settings and acquisition parameters among different institutions may affect structural visualization and quantitative measurements; therefore, our findings should be interpreted with caution when extrapolated to other imaging protocols. (2) Anterolateral structure injuries were assessed using MRI as a single detective tool, without confirmation from other imaging techniques or direct visualization, which may introduce measurement-related bias. Interpretation may be influenced by partial volume effects, particularly in individuals with relatively thin KFs or in the presence of surrounding edema. (3) Evaluation of KF injury using MRI inevitably involves subjectivity; however, independent assessment conducted by two observers and reporting of interobserver agreement were used to mitigate this bias. (4) Meniscal root integrity was not systematically evaluated owing to the absence of arthroscopic probing evidence. As lateral meniscus posterior root lesions have been reported as an independent contributor to increased ATSLC, the absence of this variable may introduce confounding factors into our research. This should be taken into account when interpreting our findings. (5) The findings of this study were based on an ACL injury cohort from a single center, which limits external validity. Moreover, limited clinical characteristics may reduce comparability with other studies. More comprehensive clinical information (e.g., activity level, sport involvement, and body mass index (BMI)), and multicenter ACL injury cohorts are warranted in further studies.
Conclusions
On the basis of single-center data, the incidence of KF injury within 12 weeks of ACL injury was 35.6%, and it was closely associated with ALL injury and LFC morphology. KF injury was independently associated with increased ATSLC, a marker of knee instability. Finally, in ACL + ALC injuries, greater LFC width ratio was identified as a potential risk factor for high-grade ATSLC.
Acknowledgements
Not applicable.
Author contributions
Conception and design: Bailin Pan, Jinjin Ma, Xiaozhuan Wang, Chuangxin Lin; analysis and interpretation of the data: all authors; drafting of the article: Bailin Pan, Shangmin Chen, Yuanying Lin; critical revision of the article for important intellectual content: Jinjin Ma, Xiaozhuan Wang; final approval of the article: Chuangxin Lin; provision of study materials: Bendan Lin, Laixi Zhou, Du Lin; statistical expertise: Shangmin Chen, Du Lin, Zhaohan Zhou; obtaining of funding: Chuangxin Lin; administrative, technical, or logistic support: Du Lin, Zhaohan Zhou, Bendan Lin, Laixi Zhou; collection and assembly of data: Bailin Pan, Shangmin Chen, Yuanying Lin.
Funding
This work was supported by grants from the National Natural Science Foundation of China (no. 82472526), the Natural Science Foundation of Guangdong Province (no. 2022A1515010431), and the Guangdong Province Science and Technology Special Fund Project (no. STKJ202209068 and no. 2025TQ09Y046).
Data availability
The data that support the findings of this study are available from the corresponding author upon reasonable request.
Declarations
Ethics approval and consent to participate
This study was conducted in accordance with the Declaration of Helsinki and was approved by the Shantou Central Hospital Ethics Committee Ethical Review Opinion (approval number: (2025) Research No.142). Written informed consent was obtained from all participants prior to inclusion.
Consent for publication
All individual personal data included in the manuscript have been obtained with the individual’s consent for submission and publication.
Competing interests
The authors declare no conflicts of interest.
Footnotes
Publisher’s Note
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Bailin Pan, Shangmin Chen, and Yuanying Lin have contributed equally to this work and share first authorship.
Contributor Information
Jinjin Ma, Email: jinjinma@scut.edu.cn.
Xiaozhuan Wang, Email: wxz24568@163.com.
Chuangxin Lin, Email: lin0604@126.com.
References
- 1.Mall NA, Chalmers PN, Moric M, Tanaka MJ, Cole BJ, Bach BR Jr et al (2014) Incidence and trends of anterior cruciate ligament reconstruction in the United States. Am J Sports Med 42:2363–2370 [DOI] [PubMed] [Google Scholar]
- 2.Musahl V, Karlsson J (2019) Anterior cruciate ligament tear. N Engl J Med 380:2341–2348 [DOI] [PubMed] [Google Scholar]
- 3.Filbay SR, Skou ST, Bullock GS, Le CY, Räisänen AM, Toomey C et al (2022) Long-term quality of life, work limitation, physical activity, economic cost and disease burden following ACL and meniscal injury: a systematic review and meta-analysis for the OPTIKNEE consensus. Br J Sports Med 56:1465–1474 [DOI] [PubMed] [Google Scholar]
- 4.Beard DJ, Davies L, Cook JA, Stokes J, Leal J, Fletcher H et al (2022) Rehabilitation versus surgical reconstruction for non-acute anterior cruciate ligament injury (ACL SNNAP): a pragmatic randomised controlled trial. Lancet 400:605–615 [DOI] [PubMed] [Google Scholar]
- 5.Brophy RH, Lowry KJ (2023) American Academy of Orthopaedic surgeons clinical practice guideline summary: management of anterior cruciate ligament injuries. J Am Acad Orthop Surg 31:531–537 [DOI] [PMC free article] [PubMed] [Google Scholar]
- 6.Willinger L, Athwal KK, Holthof S, Imhoff AB, Williams A, Amis AA (2023) Role of the anterior cruciate ligament, anterolateral complex, and lateral meniscus posterior root in anterolateral rotatory knee instability: a biomechanical study. Am J Sports Med 51:1136–1145 [DOI] [PMC free article] [PubMed] [Google Scholar]
- 7.Lee DH, Kim CH, Kim TH, Kim SG (2023) Sectioning of the anterolateral ligaments in anterior cruciate ligament sectioned knees increases internal rotation of the knee joint: a systematic review and meta-analysis of cadaveric studies. Arthroscopy 39:1692–1701 [DOI] [PubMed] [Google Scholar]
- 8.Getgood A, Brown C, Lording T, Amis A, Claes S, Geeslin A et al (2019) The anterolateral complex of the knee: results from the International ALC Consensus Group Meeting. Knee Surg Sports Traumatol Arthrosc 27:166–176 [DOI] [PubMed] [Google Scholar]
- 9.van der Wal WA, Meijer DT, Hoogeslag RAG, LaPrade RF (2024) The Iliotibial band is the main secondary stabilizer for anterolateral rotatory instability and both a Lemaire Tenodesis and anterolateral ligament reconstruction can restore native knee kinematics in the anterior cruciate ligament reconstructed knee: a systematic review of biomechanical cadaveric studies. Arthroscopy 40:632-647.e631 [DOI] [PubMed] [Google Scholar]
- 10.Batty L, Murgier J, O’Sullivan R, Webster KE, Feller JA, Devitt BM (2019) The Kaplan fibers of the iliotibial band can be identified on routine knee magnetic resonance imaging. Am J Sports Med 47:2895–2903 [DOI] [PubMed] [Google Scholar]
- 11.Watanabe S, Nagai K, Hoshino Y, Kataoka K, Nakanishi Y, Araki D et al (2022) Influence of injury to the Kaplan fibers of the iliotibial band on anterolateral rotatory knee laxity in anterior cruciate ligament injury: a retrospective cohort study. Am J Sports Med 50:3265–3272 [DOI] [PubMed] [Google Scholar]
- 12.Lord BR, Devitt BM, Hookway SR, Klemm HJ, Webster KE, Whitehead TS et al (2023) The resolution of Kaplan fiber injuries is observed in a majority of cases at 9 months after acute primary anterior cruciate ligament reconstruction: a radiological study. Am J Sports Med 51:2596–2602 [DOI] [PubMed] [Google Scholar]
- 13.Poursalehian M, Hajiaghajani S, Ayati Firoozabadi M, Dehghani Ashkezari D, Mortazavi SMJ (2024) Kaplan fibers of iliotibial band: a comprehensive review of current literature. EFORT Open Rev 9:980–989 [DOI] [PMC free article] [PubMed] [Google Scholar]
- 14.Song GY, Zhang H, Zhang J, Zhang ZJ, Zheng T, Feng H (2020) Excessive preoperative anterior tibial subluxation in extension is associated with inferior knee stability after anatomic anterior cruciate ligament reconstruction. Am J Sports Med 48:573–580 [DOI] [PubMed] [Google Scholar]
- 15.Ye Z, Wu X, Chen J, Cho E, Xie G, Dong S et al (2023) Association between anterior tibial subluxation of lateral compartment and high-grade knee laxity in patients with anterior cruciate ligament deficiency. Am J Sports Med 51:1698–1707 [DOI] [PubMed] [Google Scholar]
- 16.Lian J, Novaretti JV, Sheean AJ, Patel NK, Whaley S, Popchak A et al (2019) Static lateral tibial plateau subluxation predicts high-grade rotatory knee laxity in anterior cruciate ligament-deficient knees. Am J Sports Med 47:277–284 [DOI] [PubMed] [Google Scholar]
- 17.Zheng T, Song G, Wang C, Li Y, Zhang Z, Cao Y et al (2023) Effect of anterolateral ligament status and inherent knee anatomy on anterior tibial subluxation of the lateral compartment after acute anterior cruciate ligament injury: a cohort study based on MRI analysis. Am J Sports Med 51:968–976 [DOI] [PubMed] [Google Scholar]
- 18.Zheng T, Song GY, Feng H, Zhang H, Li Y, Li X et al (2020) Lateral meniscus posterior root lesion influences anterior tibial subluxation of the lateral compartment in extension after anterior cruciate ligament injury. Am J Sports Med 48:838–846 [DOI] [PubMed] [Google Scholar]
- 19.Batty LM, Murgier J, Feller JA, O’Sullivan R, Webster KE, Devitt BM (2020) Radiological identification of injury to the kaplan fibers of the iliotibial band in association with anterior cruciate ligament injury. Am J Sports Med 48:2213–2220 [DOI] [PubMed] [Google Scholar]
- 20.Helito CP, Helito PVP, Leão RV, Demange MK, Bordalo-Rodrigues M (2017) Anterolateral ligament abnormalities are associated with peripheral ligament and osseous injuries in acute ruptures of the anterior cruciate ligament. Knee Surg Sports Traumatol Arthrosc 25:1140–1148 [DOI] [PubMed] [Google Scholar]
- 21.Van Haver A, De Roo K, De Beule M, Van Cauter S, Audenaert E, Claessens T et al (2014) Semi-automated landmark-based 3D analysis reveals new morphometric characteristics in the trochlear dysplastic femur. Knee Surg Sports Traumatol Arthrosc 22:2698–2708 [DOI] [PubMed] [Google Scholar]
- 22.McDonald LS, van der List JP, Jones KJ, Zuiderbaan HA, Nguyen JT, Potter HG et al (2017) Passive anterior tibial subluxation in the setting of anterior cruciate ligament injuries: a comparative analysis of ligament-deficient states. Am J Sports Med 45:1537–1546 [DOI] [PubMed] [Google Scholar]
- 23.Iwaki H, Pinskerova V, Freeman MA (2000) Tibiofemoral movement 1: the shapes and relative movements of the femur and tibia in the unloaded cadaver knee. J Bone Joint Surg Br 82:1189–1195 [DOI] [PubMed] [Google Scholar]
- 24.Tanaka MJ, Jones KJ, Gargiulo AM, Delos D, Wickiewicz TL, Potter HG et al (2013) Passive anterior tibial subluxation in anterior cruciate ligament-deficient knees. Am J Sports Med 41:2347–2352 [DOI] [PubMed] [Google Scholar]
- 25.Mandrekar JN (2010) Receiver operating characteristic curve in diagnostic test assessment. J Thorac Oncol 5:1315–1316 [DOI] [PubMed] [Google Scholar]
- 26.McHugh ML (2012) Interrater reliability: the kappa statistic. Biochem Med (Zagreb) 22:276–282 [PMC free article] [PubMed] [Google Scholar]
- 27.Koo TK, Li MY (2016) A guideline of selecting and reporting intraclass correlation coefficients for reliability research. J Chiropr Med 15:155–163 [DOI] [PMC free article] [PubMed] [Google Scholar]
- 28.Monaco E, Helito CP, Redler A, Argento G, De Carli A, Saithna A et al (2019) Correlation between magnetic resonance imaging and surgical exploration of the anterolateral structures of the acute anterior cruciate ligament-injured knee. Am J Sports Med 47:1186–1193 [DOI] [PubMed] [Google Scholar]
- 29.Berthold DP, Willinger L, Muench LN, Forkel P, Schmitt A, Woertler K et al (2020) Visualization of proximal and distal Kaplan fibers using 3-dimensional magnetic resonance imaging and anatomic dissection. Am J Sports Med 48:1929–1936 [DOI] [PubMed] [Google Scholar]
- 30.Shi BY, Levine B, Ghazikhanian V, Bugarin A, Schroeder G, Wu S et al (2022) Reliability of MRI detection of kaplan fiber injury in pediatric and adolescent patients with ACL tears. Orthop J Sports Med 10:23259671221128600 [DOI] [PMC free article] [PubMed] [Google Scholar]
- 31.Han AX, Tan TJ, Nguyen T, Lee DYH (2020) Timing of magnetic resonance imaging affects the accuracy and interobserver agreement of anterolateral ligament tears detection in anterior cruciate ligament deficient knees. Knee Surg Relat Res 32:64 [DOI] [PMC free article] [PubMed] [Google Scholar]
- 32.Saithna A, Helito CP, Vieira TD, Sonnery-Cottet B, Muramatsu K (2021) The anterolateral ligament has limited intrinsic healing potential: a serial, 3-dimensional-magnetic resonance imaging study of anterior cruciate ligament-injured knees from the SANTI Study Group. Am J Sports Med 49:2125–2135 [DOI] [PubMed] [Google Scholar]
- 33.Berthold DP, Willinger L, LeVasseur MR, Marrero DE, Bell R, Muench LN et al (2021) High rate of initially overlooked Kaplan fiber complex injuries in patients with isolated anterior cruciate ligament injury. Am J Sports Med 49:2117–2124 [DOI] [PMC free article] [PubMed] [Google Scholar]
- 34.Devitt BM, Al’khafaji I, Blucher N, Batty LM, Murgier J, Webster KE et al (2021) Association between radiological evidence of Kaplan fiber injury, intraoperative findings, and pivot-shift grade in the setting of acute anterior cruciate ligament injury. Am J Sports Med 49:1262–1269 [DOI] [PubMed] [Google Scholar]
- 35.Lynch TB, Swan ER, Cognetti D, Arana Mireles A, Byerly D, Bernot JM et al (2022) MRI does not reliably detect kaplan fiber injury in skeletally immature patients with an acute ACL tear. Orthop J Sports Med 10:23259671221130356 [DOI] [PMC free article] [PubMed] [Google Scholar]
- 36.Balendra G, Willinger L, Pai V, Mitchell A, Lee J, Jones M et al (2022) Anterolateral complex injuries occur in the majority of “isolated” anterior cruciate ligament ruptures. Knee Surg Sports Traumatol Arthrosc 30:176–183 [DOI] [PubMed] [Google Scholar]
- 37.Kraeutler MJ, Welton KL, Chahla J, LaPrade RF, McCarty EC (2018) Current concepts of the anterolateral ligament of the knee: anatomy, biomechanics, and reconstruction. Am J Sports Med 46:1235–1242 [DOI] [PubMed] [Google Scholar]
- 38.Cui J, Cheng S, Luo Y, Li Q, Li F, Wang Y et al (2024) Influence of injury to the Kaplan fibers and anterolateral ligament on pivot-shift phenomenon in adult and adolescent patients with anterior cruciate ligament injury: a retrospective cohort study. Orthop J Sports Med 12:23259671241288250 [DOI] [PMC free article] [PubMed] [Google Scholar]
- 39.Helito PVP, Helito CP, Rodrigues MB (2023) Anterolateral ligament MRI of the knee in ACL injuries: MRI abnormalities association with instability. Eur Radiol 33:1456–1464 [DOI] [PubMed] [Google Scholar]
- 40.Li R, Yuan X, Fang Z, Liu Y, Chen X, Zhang J (2020) A decreased ratio of height of lateral femoral condyle to anteroposterior diameter is a risk factor for anterior cruciate ligament rupture. BMC Musculoskelet Disord 21:402 [DOI] [PMC free article] [PubMed] [Google Scholar]
- 41.Vasta S, Andrade R, Pereira R, Bastos R, Battaglia AG, Papalia R et al (2018) Bone morphology and morphometry of the lateral femoral condyle is a risk factor for ACL injury. Knee Surg Sports Traumatol Arthrosc 26:2817–2825 [DOI] [PubMed] [Google Scholar]
- 42.Choi NH, Lee DM, Shin HJ, Victoroff BN (2023) Combined anterolateral ligament and anterior cruciate ligament injury is associated with increased lateral femoral condyle ratio. Arthroscopy 39:1235–1241 [DOI] [PubMed] [Google Scholar]
- 43.Pfeiffer TR, Burnham JM, Hughes JD, Kanakamedala AC, Herbst E, Popchak A et al (2018) An increased lateral femoral condyle ratio is a risk factor for anterior cruciate ligament injury. J Bone Joint Surg Am 100:857–864 [DOI] [PubMed] [Google Scholar]
- 44.Geeslin AG, Chahla J, Moatshe G, Muckenhirn KJ, Kruckeberg BM, Brady AW et al (2018) Anterolateral knee extra-articular stabilizers: a robotic sectioning study of the anterolateral ligament and distal iliotibial band Kaplan fibers. Am J Sports Med 46:1352–1361 [DOI] [PubMed] [Google Scholar]
- 45.Farinelli L, Meena A, Sonnery-Cottet B, Vieira TD, Pioger C, Tapasvi S et al (2023) Distal Kaplan fibers and anterolateral ligament injuries are associated with greater intra-articular internal tibial rotation in ACL-deficient knees based on magnetic resonance imaging. J Exp Orthop 10:113 [DOI] [PMC free article] [PubMed] [Google Scholar]
- 46.Collins MS, Bond JR, Crush AB, Stuart MJ, King AH, Levy BA (2015) MRI injury patterns in surgically confirmed and reconstructed posterolateral corner knee injuries. Knee Surg Sports Traumatol Arthrosc 23:2943–2949 [DOI] [PubMed] [Google Scholar]
- 47.Rakhra KS, Delorme JP, Sanders B, Liew A (2022) The diagnostic accuracy of MRI for evaluating the posterolateral corner in acute knee dislocation. Eur Radiol 32:6752–6758 [DOI] [PubMed] [Google Scholar]
- 48.Temponi EF, de Carvalho Júnior LH, Saithna A, Thaunat M, Sonnery-Cottet B (2017) Incidence and MRI characterization of the spectrum of posterolateral corner injuries occurring in association with ACL rupture. Skeletal Radiol 46:1063–1070 [DOI] [PubMed] [Google Scholar]
- 49.Zhang ZY, Wang C, Maimaitimin M, Huang HJ, Pan XY, Maimaitijiang P et al (2021) Anterior and rotational tibial subluxation in the setting of anterior cruciate ligament injuries: An MRI analysis. Knee 33:365–373 [DOI] [PubMed] [Google Scholar]
- 50.Fernandes MS, Pereira R, Andrade R, Vasta S, Pereira H, Pinheiro JP et al (2017) Is the femoral lateral condyle’s bone morphology the trochlea of the ACL? Knee Surg Sports Traumatol Arthrosc 25:207–214 [DOI] [PubMed] [Google Scholar]
- 51.Zhang ZY, Pan XY, Maimaitijiang P, Meng LY, He ZY, Zhao Q et al (2022) Anterior tibial subluxation measured under a modified protocol is positively correlated with posterior tibial slope: a comparative study of MRI measurement methods. Knee Surg Sports Traumatol Arthrosc 30:3350–3360 [DOI] [PubMed] [Google Scholar]
- 52.Bernholt D, DePhillipo NN, Aman ZS, Samuelsen BT, Kennedy MI, LaPrade RF (2021) Increased posterior tibial slope results in increased incidence of posterior lateral meniscal root tears in ACL reconstruction patients. Knee Surg Sports Traumatol Arthrosc 29:3883–3891 [DOI] [PubMed] [Google Scholar]
- 53.Ye Z, Xu J, Chen J, Qiao Y, Wu C, Xie G et al (2022) Steep lateral tibial slope measured on magnetic resonance imaging is the best radiological predictor of anterior cruciate ligament reconstruction failure. Knee Surg Sports Traumatol Arthrosc 30:3377–3385 [DOI] [PubMed] [Google Scholar]
- 54.Song GY, Zhang H, Zhang J, Liu X, Xue Z, Qian Y et al (2018) Greater static anterior tibial subluxation of the lateral compartment after an acute anterior cruciate ligament injury is associated with an increased posterior tibial slope. Am J Sports Med 46:1617–1623 [DOI] [PubMed] [Google Scholar]
Associated Data
This section collects any data citations, data availability statements, or supplementary materials included in this article.
Data Availability Statement
The data that support the findings of this study are available from the corresponding author upon reasonable request.