Lateral Posterior Tibial Slope Research Articles

Paper 25: The Impact of Posterior Tibial Slope on Meniscal Injury in Acute ACL Ruptures: A Large, Retrospective Registry Study

Objectives: Increased posterior tibial slope has previously been associated with an elevated risk of anterior cruciate ligament (ACL) rupture. Recent studies have suggested there may be a relationship between posterior slope and meniscal tears in ACL ruptures, however, these studies have either included chronic ACL injuries, revision ACL reconstructions or an overall low number of study participants. The goal of this study is to leverage a large ACL registry to assess the impact of posterior tibial slope on meniscal tears in acute ACL ruptures. Methods: A large, single-institution knee registry was consulted to identify all patients between the age of 18 and 45 who underwent primary ACL reconstruction between Jan 2019 and July 2022 for acute, noncontact ACL rupture, defined as undergoing surgery within 90 days of injury. Patients with pre-existing meniscal pathology, chronic ACL reconstructions, revisions, multi-ligament knee injuries and nonoperatively managed ACL injuries were excluded. Preoperative MRIs were used to measure lateral and medial posterior tibial slope for all patients. Meniscal injury seen in-situ during arthroscopy was recorded based on operative reports. Demographics data, including age, sex, and body mass index, was also recorded. Independent cohorts were created based on the presence or absence of any meniscal injury. Two-tailed student’s t tests were used to compare average medial and lateral posterior tibial slopes between these groups. Separate analyses were also performed to assess the impact of posterior slope on medial and lateral meniscus tears independently. Multiple logistic regression was carried out to determine risk factors for meniscal injury in this population. Results: 1059 patients ultimately met inclusion criteria. The average age was 29.5 and there were 532 (50%) women. There were 253 (24%) patients with isolated lateral meniscus tears, 152 (14%) patients with isolated medial meniscus tears and 93 (9%) patients with both medial and lateral tears. The average lateral and medial posterior tibial slopes were 5.54 (-4.2 to 13.4) and 5.67 (0 to 15.7), respectively. Increased lateral tibial slope was associated with a statistically significant increase in rate of any meniscal tear (p=.0022). Lateral slope was also associated with a higher rate of lateral meniscal tears, specifically (p=.0009). Multiple logistic regression identified elevated BMI and male sex as independent risk factors for meniscal injury in this population. Conclusions: Increased lateral posterior tibial slope is associated with a higher rate of meniscus injury in acute ACL ruptures and should be considered when devising treatment algorithms for patients in this population. [Table: see text][Table: see text][Table: see text][Table: see text]

Posterior Tibial Slope in Patients Undergoing Bilateral Versus Unilateral ACL Reconstruction: MRI and Radiographic Analyses

Background: An increased posterior tibial slope (PTS) is a risk factor for primary anterior cruciate ligament (ACL) tears and graft failure, but the PTS has not been well-defined in those who have experienced bilateral ACL injuries. Purpose: The primary aim was to compare the PTS, as well as the rate of an elevated PTS (>12° on lateral radiography; >7° on magnetic resonance imaging [MRI]), between patients who have undergone bilateral ACL reconstruction (ACLR) versus unilateral ACLR. A secondary purpose was to examine whether these associations remained consistent on both plain radiography and MRI. Study Design: Cross-sectional study; Level of evidence, 3. Methods: We retrospectively identified patients who underwent primary ACLR at our institution from the years 2012 to 2020. Patients who underwent nonsimultaneous bilateral ACLR (n = 53) were matched to those who underwent unilateral ACLR (n = 53) by age, sex, and body mass index. Exclusion criteria were rotated lateral radiographs, MRI scans of inadequate quality, and concomitant ligament injuries or fractures. Those who had undergone unilateral ACLR with <5-year follow-up were further excluded. There were 3 blinded readers who measured the PTS on lateral radiographs, while the medial PTS (MPTS) and lateral PTS (LPTS) were measured on MRI scans. Bivariate regression was performed to determine the correlation between radiographic and MRI measurements. Results: The PTS on radiography (11.26° vs 10.13°, respectively; P = .044) and the LPTS on MRI (7.32° vs 6.08°, respectively; P = .012) in the bilateral ACLR group were significantly greater than those in the unilateral ACLR group but not the MPTS on MRI (4.55° vs 4.17°, respectively; P = .590). The percentage of patients in the bilateral group with a radiographic PTS >12° was 41.0% compared with 13.2% in the unilateral group (P = .012). The bilateral group had a significantly higher rate of an LPTS >7° compared with the unilateral group (53.8% vs 32.1%, respectively; P = .016) but not for an MPTS >7° (P = .190). On MRI, the LPTS (6.90°± 2.73°) was significantly greater than the MPTS (4.41°± 2.92°) (P < .001). There was a weak correlation between MPTS and radiographic PTS measurements (R = 0.24; P = .021), but LPTS and radiographic PTS measurements were not significantly correlated (R = 0.03; P = .810). Conclusion: Patients who underwent bilateral ACLR had a significantly greater PTS on radiography and a significantly greater LPTS on MRI compared with those who underwent unilateral ACLR. The rate of a radiographic PTS >12° was 2.4 times greater among patients undergoing bilateral ACLR compared with those undergoing unilateral ACLR. PTS measurements on radiography demonstrated a weak to negligible correlation with PTS measurements on MRI, suggesting that future normative PTS values should be reported specific to the imaging modality.

Paper 24: Reliability of Posterior Tibial Slope Measurement on Magnetic Resonance Imaging Versus Computed Tomography

Objectives: Increased posterior tibial slope (PTS) has been linked to higher rates of anterior cruciate ligament (ACL) injury and ACL graft failure post-reconstruction. In recent years, more specific investigations have delineated distinct roles of the medial tibial plateau (MTP) and lateral tibial plateau (LTP) geometries on anteroposterior and rotatory stability of the knee. While the diagnostic workup of patients with ACL insufficiency typically consists of radiographs and magnetic resonance imaging (MRI), computed tomography (CT), which is the gold standard for evaluating the osseous geometry of the proximal tibia, is not routinely obtained. With increased understanding of the roles of the MTP and LTP geometries on tibiofemoral kinematics, accurate sagittal slope measurements of both the MTP and LTP will be crucial for further defining the treatment algorithm for ACL insufficiency. It is currently unknown whether traditional MRI can be used to accurately measure PTS and how well these measurements correlate to those on CT. Therefore, the purpose of this study was to compare PTS measurements of the MTP and LTP on MRI versus CT. Methods: After Institutional Review Board approval was obtained, an institutional picture archiving and communication system imaging database was retrospectively queried for patients that received concurrent MRI and CT imaging of the same knee within a one-year interval. Knees with significant arthrosis (Kellgren-Lawrence grade &gt;2), deformity, proximal tibia fracture, or artifact that obscured visualization of proximal tibia landmarks were excluded. On paired MRI and CT studies, PTS of the MTP and LTP were measured using a previously described, validated method (Hudek et al, Clin Orthop Relat Res, 2009) by two independent raters (Figure 1). Interrater reliability of PTS measurements was assessed using the intraclass correlation coefficient (ICC). Intermethod agreement between MRI and CT measurements was assessed using the ICC and Bland-Altman analysis. Results: A total of 41 knees in 40 patients (mean age, 37.9±13.4 years, 78.0% male) met final inclusion criteria. Interrater reliability was moderate for MRI measurements (ICC = 0.62-0.73) and high for CT measurements (ICC = 0.83-0.86). Mean measurements of PTS at the MTP were 3.3±2.8° (range, -4.7-8.4°) and 3.7±3.1° (range, -3.8-10.4°) on MRI and CT, respectively. Mean measurements of PTS at the LTP were 4.5±3.8° (range, -8.0-10.6°) and 5.2±3.6° (range, -3.6-15.7°) on MRI and CT, respectively. The mean absolute differences in PTS measurements between MRI and CT were 2.6±2.1° and 2.6±2.6° at the MTP and LTP, respectively. Poor intermethod agreement between MRI and CT was observed at the MTP (ICC = 0.31-0.41), while moderate intermethod agreement was observed at the LTP (ICC = 0.61-0.62). Bland-Altman plots demonstrated high variability and minimal bias of PTS measurements on MRI compared to CT (-0.9° [95% Limit of Agreement (LOA) -7.5-5.6°] for MTP; -1.0° [95% LOA -7.2-5.2°] for LTP) (Figure 2). Conclusions: With increased understanding of the roles of the medial and lateral tibial plateau geometries on tibiofemoral stability in the setting of ACL insufficiency, accurate measurements of PTS are necessary to guide treatment decisions. In this study, PTS measurements on MRI demonstrated lower interrater reliability compared to PTS measurements on CT. Poor-to-moderate agreement was observed for measurements of PTS of the MTP and LTP between paired MRI and CT studies, with high variability and minimal bias. Therefore, measurements of medial and lateral PTS may not be reliable on traditional MRI.

Relationship Between Lateral Tibial Posterior Slope and Tibiofemoral Kinematics During Simulated Jump Landings in Male Cadaveric Knees.

It is not known mechanistically whether a steeper lateral posterior tibial slope (LTS) leads to an increase in anterior tibial translation (ATT) as well as internal tibial rotation (ITR) during a given jump landing. A steeper LTS will result in increased ATT and ITR during simulated jump landings when applying knee compression, flexion, and internal tibial torque of increasing severity. Descriptive laboratory study. Seven pairs of cadaveric knees were harvested from young male adult donors (mean ± SD; age, 25.71 ± 5.53 years; weight, 71.51 ± 4.81 kg). The LTS of each knee was measured by a blinded observer from 3-T magnetic resonance images. Two sets of 25 impact trials of ∼700 N (1× body weight [BW] ±10%) followed by 2 sets of 25 trials of 1400 N (2× BW ±10%) were applied to a randomly selected knee of each pair. Similarly, on the contralateral knee, 2 sets of 25 impact trials of ∼1800 N (2.5× BW ±10%) followed by 2 sets of 25 trials of ∼2100 N (3× BW ±10%) were applied. Three-dimensional knee kinematics, including ATT and ITR, were measured at 400 Hz using optoelectronic motion capture. Two-factor linear mixed effect models were used to determine the relationship of LTS to ATT and ITR as impact loading increased. As LTS increased, so did ATT and ITR during increasingly severe landings. LTS had an increasing effect on ATT (coefficient, 0.50; 95% CI, 0.29-0.71) relative to impact force (coefficient, 0.52; 95% CI, 0.50-0.53). ITR was proportional to LTS (coefficient, 1.36; 95% CI, 0.80-1.93) under increasing impact force (coefficient, 0.49; 95% CI, 0.47-0.52). For steeper LTS, the increase in ITR was proportionally greater than the increase in ATT. In male knee specimens, a steeper LTS significantly increased ATT and ITR during jump landings. Increases in ITR and ATT during jump landings lead to increased strain on the anterior cruciate ligament and are therefore associated with greater risk of ligament failure.

Association of Tibial Tubercle–Trochlear Groove Distance With Risk of ACL Graft Failure

Background: Limited evidence suggests a positive correlation between tibial tubercle–trochlear groove (TT-TG) distance and the risk of native anterior cruciate ligament (ACL) tear. The relationship between TT-TG distance and the risk of ACL graft failure is unknown. Hypothesis: TT-TG distance is independently associated with risk of ACL graft failure. Study Design: Cohort study; Level of evidence, 3. Methods: All patients who underwent ACL revision surgery between 2010 and 2018 at a single institution were identified. A control cohort underwent primary ACL reconstruction (ACLR) between 2006 and 2015, with no evidence of graft failure at 8.1 ± 2.5 years postoperatively. Record review included anthropometrics, graft type, and estimated Tegner activity score at ≥6 months after primary ACLR. Magnetic resonance imaging (MRI) scans after native ACL tear (controls) or graft failure (revision cohort) were assessed for (1) TT-TG distance, (2) proximal tibial slopes, (3) depth of tibial plateau concavity, and (4) tunnel position (revision cohort). Associations between ACL graft failure and MRI measurements, surgical variables, and patient characteristics were evaluated with logistic regression analyses. Sensitivity analyses, excluding patients with tunnel malposition, were performed to confirm multivariable results in patients with “ideal” tunnel placement. Results: Participants included 153 patients who underwent revisions and 144 controls. Controls were older than the patients who underwent revision (26.6 ± 8.8 vs 20.6 ± 7.3 years; P &lt; .001). The mean TT-TG distance and lateral posterior tibial slope (PTS) were smaller for the control group than for the revision group (TT-TG: 9.3 ± 3.9 vs 11.2 ± 4.2 mm; P &lt; .001; lateral PTS: 6.2° ± 3.3° vs 7.2° ± 3.6°; P = .01). TT-TG distance, lateral PTS, and age were associated with risk of ACL graft failure by multivariable analysis (OR, 1.15; 95% CI, 1.07-1.23; P &lt; .001; OR, 1.13; 95% CI, 1.04-1.22; P = .004; and OR, 0.90; 95% CI, 0.87-0.94; P &lt; .001, respectively). With sensitivity analyses, TT-TG distance, lateral PTS, and age at index surgery remained significantly and independently associated with ACL graft failure. Conclusion: Increased TT-TG distance, increased lateral PTS, and younger age are independently associated with increased odds of ACL graft failure. Patients with these characteristics may require a more comprehensive strategy to reduce the risk of ACL reinjury.

Bone Morphological Characteristics as Risk Factors for Anterior Cruciate Ligament Injury: Comparison Between Contact and Noncontact Injury

Background: Altered bone morphologies are considered risk factors for noncontact anterior cruciate ligament (ACL) injuries. Purpose/Hypothesis: This study aimed to investigate bone morphological characteristics as risk factors for ACL tears in contact injuries and compare these factors with those for noncontact ACL injuries. We hypothesized that altered bone morphologies would also be risk factors for contact ACL injury. Study Design: Cross-sectional study; Level of evidence, 3. Methods: Enrolled were patients who underwent primary ACL reconstructions between January 2000 and December 2021 within 6 weeks after injury. Patients in the ACL group were classified according to injury mechanism (contact vs noncontact). During the same period, a control group of patients matched by age, height, and body mass index to the ACL group was selected. The lateral femoral condylar ratio (LFCR), notch width index (NWI), and lateral posterior tibial slope (PTS) were measured. Measured parameters were compared between the control, contact, and noncontact groups using analysis of variance. Results: There were 86 patients in the control group, 102 patients in the contact ACL group, and 105 patients in the noncontact ACL group. The demographic characteristics of the 3 groups did not differ significantly. The contact group had significantly higher LFCRs and lower NWIs compared with the control group ( P &lt; .001 and P = .001, respectively). The noncontact group had significantly higher LFCRs and PTSs and lower NWIs compared with the control group ( P = .031; P &lt; .001; and P &lt; .001, respectively). The noncontact group had significantly higher PTSs and lower NWIs compared with the contact group ( P = .003 and P =.014, respectively). In the contact group, the LFCR, PTS, and NWI were significant risk factors for ACL tears (odds ratio [OR], 1.25 [ P &lt; .001]; OR, 1.16 [ P = .008]; and OR, 1.27 [ P = .001], respectively), and in the noncontact group, the PTS and NWI were significant risk factors for ACL tears (OR, 1.20 [ P &lt; .001]; OR, 1.59 [ P &lt; .001], respectively). Conclusion: Altered bone morphological characteristics of the knee were found to be risk factors for ACL tears in contact injuries as well as noncontact injuries. Altered morphology has a more significant effect in noncontact ACL injuries.

Anatomical factors associated with the development of anterior tibial spine fractures based on MRI measurements

BackgroundNumerous studies have investigated anatomic factors for anterior cruciate ligament (ACL) injuries, such as posterior tibial slope (PTS) and notch width index (NWI). However, anterior tibial spine fracture (ATSF) as a specific pattern of ACL injury, a bony avulsion of the ACL from its insertion on the intercondylar spine of the tibia, has rarely been explored for its anatomical risk factors. Identifying anatomic parameters of the knee associated with ATSF is important for understanding injury mechanisms and prevention.MethodsPatients who underwent surgery for ATSF between January 2010 and December 2021 were retrospectively reviewed, and 38 patients were included in the study group. Thirty-eight patients who suffered from isolated meniscal tear without other pathologic findings were matched in a 1:1 fashion by age, sex and BMI to the study group. The lateral posterior tibial slope (LPTS), medial posterior tibial slope (MPTS), medial tibial depth, lateral tibial height, lateral femoral condyle ratio (LFCR) and NWI were measured and compared between the ATSF and control groups. Binary logistic regressions identified independent predictors of ATSF. Receiver operator characteristic (ROC) curves were performed to compare the diagnostic performance and determine the cutoff values of associated parameters.ResultsThe LPTS, LFCR and MPTS were significantly larger in the knees in the ATSF group than in the control group (P = 0.001, P = 0.012 and P = 0.005, respectively). The NWI was significantly smaller in the knees in the ATSF group than in the control group (P = 0.005). According to the results of logistic regression analysis, the LPTS, LFCR and NWI were independently associated with ATSF. The LPTS was the strongest predictor variable, and the ROC analysis revealed 63.2% sensitivity and 76.3% specificity (area under the curve, 0.731; 95% CI 0.619–0.844) for values above 6.9.ConclusionThe LPTS, LFCR and NWI were found to be associated with the ATSF; in particular, LPTS could provide the most accurate predictive performance. The findings of this study may aid clinicians in identifying people at risk for ATSF and taking individualized preventive measures. However, further investigation regarding the pattern and biomechanical mechanisms of this injury is required.

Effect of demographic features on morphometric variables of the knee joint: Sample of a 20 to 40-year-old Turkish population.

This study aimed to investigate the relationship between body mass index (BMI), age, and sex and morphological risk factors that may cause internal knee injuries. The magnetic resonance images of 728 participants who met the inclusion criteria and had a mean age of 34.4 ± 6.8 years were analyzed retrospectively. Demographic differences were analyzed by measuring 17 morphological parameters known to be associated with internal knee injuries. Men had a higher anterior cruciate ligament length (ACLL), anterior cruciate ligament width, (ACLW) lateral femoral condylar width (LFCW), medial femoral condylar width (MFCW), lateral femoral condylar depth (LFCD), distal femoral width (DFW), and intercondylar femoral width (IFW) than women (P < .05). By contrast, the medial meniscus bone angle (MMBA) was lower in men than in women (P < .05). Women aged 31 to 40 years had a lower Insall-Salvati index (ISI) and lateral tibial posterior slope (LTPS) than those aged 21 to 30 years (P < .05), whereas men aged 31 to 40 years had a lower ISI than those aged 21 to 30 years (P < .05). Women with BMI ≥ 30 had a higher LFCW and MFCW but a lower ISI than those with BMI < 30 (P < .05). Men with BMI ≥ 30 had a higher LFCW, MFCW, DFW, and MMBA than those with BMI < 30 (P < .05). The use of value ranges structured according to demographic characteristics, rather than a single value range for all patient groups, may contribute to the evaluation and treatment of the morphological features that are thought to be effective in the development of internal knee injuries. These values may also shed light on future radiological risk scoring systems and artificial intelligence applications in medicine.

Effect of Posterior Tibial Slopes on Graft Survival Rates at 10 Years After Primary Single-Bundle Posterior Cruciate Ligament Reconstruction

Background: Recent biomechanical studies have reported that stress on the posterior cruciate ligament (PCL) graft increases as the posterior tibial slope (PTS) decreases (flattened) in knees with single-bundle (SB) and double-bundle PCL reconstruction. Clinical studies of SB PCL reconstruction have shown that a flattened PTS is associated with a lesser reduction in posterior tibial translation. There is no long-term study on the clinical outcomes and graft survival rates of SB PCL reconstruction based on the medial and lateral PTSs measured on magnetic resonance imaging. Hypothesis: Flattened medial and lateral PTSs are associated with poor clinical outcomes and graft survival rates at a minimum 10-year follow-up after SB PCL reconstruction. Study Design: Cohort study; Level of evidence, 3. Methods: In this cohort study, we retrospectively reviewed 46 patients (mean age, 28.8 ± 9.9 years) who underwent primary SB PCL reconstruction between 2000 and 2009. They were followed up for a minimum of 10 years. The medial and lateral PTSs were measured on preoperative magnetic resonance imaging. As a previous study reported that a steeper medial or lateral PTS showed a higher risk of anterior tibial translation at thresholds of 5.6° and 3.8°, respectively, the patients were divided into 2 groups based on the cutoff values of both the medial (≤5.6° vs >5.6°) and lateral (≤3.8° vs >3.8°) PTSs. Clinical scores (International Knee Documentation Committee subjective score, Lysholm score, and Tegner activity score), radiological outcomes (side-to-side difference [SSD] on stress radiography and osteoarthritis progression), and graft survival rates were compared between the groups at the last follow-up. Results: All clinical scores and the progression of osteoarthritis demonstrated no significant difference between the 2 subgroups of both the medial and lateral PTS groups. The mean SSD on stress radiography after SB PCL reconstruction was significantly greater in patients with a medial PTS ≤5.6° than in patients with a medial PTS >5.6° (8.4 ± 3.9 vs 5.1 ± 2.9 mm, respectively; P = .030), while the lateral PTS subgroups after SB PCL reconstruction demonstrated no significant difference. The minimum 10-year graft survival rate was significantly lower in patients with a medial PTS ≤5.6° (68.4% vs 92.6%, respectively; P = .029) and a lateral PTS ≤3.8° (50.0% vs 91.7%, respectively; P = .001). Conclusion: A flattened medial PTS (≤5.6°) was associated with an increased SSD on stress radiography, and both flattened medial (≤5.6°) and lateral (≤3.8°) PTSs resulted in lower graft survival rates at a minimum 10-year follow-up after primary SB PCL reconstruction.

Elevated Posterior Tibial Slope Is Associated With Anterior Cruciate Ligament Reconstruction Failures: A Systematic Review and Meta-analysis

To evaluate the association of posterior tibial slope (PTS) with anterior cruciate ligament (ACL) reinjury following primary ACL reconstruction. PubMed, Scopus, Embase, and CINAHL databases were searched from inception through March 1, 2021, to retrieve relevant studies. Comparative studies reporting PTS measurements in a cohort of patients experiencing ACL graft failure versus patients with intact primary ACL reconstruction or studies comparing patients undergoing revision ACL reconstruction versus primary ACL reconstruction were included for analysis. A random-effects model was used to calculate the overall standardized mean difference (SMD) between groups. The following inclusion criteria were used: English language; full text available; Level I, II, or III evidence; studies in humans; and skeletally mature patients. After we systematically screened 1,912 studies, 15 studies met the inclusion/exclusion criteria. Radiographic measurements were used in 6 studies reporting medial PTS in 411 ACL failures versus 2808 controls. Patients with ACL failure had significantly greater medial PTS compared with controls (SMD 0.50; 95% confidence interval [CI] 0.23-0.77; P < .001). Magnetic resonance imaging (MRI) was used in 9 studies reporting lateral PTS measurements in 641 patients with a failed ACL reconstruction compared with 705 controls. Seven of the MRI studies also measured medial PTS in 552 failures versus 641 controls. Patients with ACL failure had significantly greater lateral PTS on MRI (SMD 0.58; 95% CI 0.13-1.03; P= .012) and medial PTS on MRI (SMD 0.59; 95% CI 0.23-0.96; P= .001) compared with controls. The present meta-analysis demonstrated that patients with elevated PTS on radiographs and MRI are at increased risk for ACL graft failure after primary ACL reconstruction. Level III, meta-analysis of Level III studies.

The morphology of the femoral posterior condyle affects the external rotation of the femur

PurposeThe purpose of this study was to identify factors related to the external rotation of the femur during knee flexion.MethodsThree-dimensional (3D) digital models of the femur and tibia were reconstructed from computed tomography images of 41 healthy Japanese subjects. Thirteen parameters related to femoral and tibial morphology and alignment of the lower extremities were evaluated, including the inclination angle of the posterior lateral and medial femoral condyles, the ratio of the medial and lateral posterior condyle radii approximated as spheres, the spherical condylar angle, the posterior condylar angle, the medial and lateral posterior tibial slope, the difference of medial and lateral posterior tibial slope, the tibiofemoral rotation angle, the 3D femorotibial angle, the 3D hip-knee-ankle angle, and the passing point of the weight-bearing line (medial–lateral and anterior–posterior). The rotation angle of the femur relative to the tibia during squatting was investigated using a 3D to 2D image matching technique and the relationships with the13 parameters were determined.ResultsThe femur externally rotated substantially up to 20° of knee flexion (9.2° ± 3.7°) and gently rotated after 20° of knee flexion (12.8° ± 6.2°). The external rotation angle at 20°–120° of knee flexion correlated with the spherical condylar angle, the tibiofemoral rotation angle and the inclination angle of the posterior medial condyles (correlation coefficient; 0.506, 0.364, 0.337, respectively).ConclusionThe parameter that was most related to the external rotation of the femur during knee flexion was the spherical condylar angle.Level of EvidenceIV

Morphological Risk Factors for Posterior Cruciate Ligament Tear and Tibial Avulsion Injuries of the Tibial Plateau and Femoral Condyle

Background: Identification of morphological risk factors associated with the knee that threaten ligaments is important for understanding injury mechanisms and prevention. However, the morphological risk factors for posterior cruciate ligament (PCL) lesions are not clearly understood. Purpose: To investigate whether the medial tibial depth (MTD), medial and lateral posterior tibial slope, asymmetry of the medial and lateral slopes, radius of the sagittal plane medial femoral condyle, coronal tibial slope, and notch width index (NWI) were risk factors for PCL intrasubstance tearing (PCLIT) and tibial avulsion fractures (PCLAF). Study Design: Cross-sectional study; Level of evidence, 3. Methods: Between January 2015 and March 2022, 82 patients with isolated PCLIT, 68 patients with isolated PCLAF, and 82 controls without any ligamentous or meniscal pathologic findings as determined via physical examination and magnetic resonance imaging were included. Values were compared among the 3 groups. Logistic regression analysis was performed to confirm the risk factors. Receiver operating characteristic curves were defined for the morphological indicators and combination of risk factors. Results: Logistic regression analysis revealed (1) MTD, lateral minus medial posterior tibial slope, radius of the posterior circle of the medial femoral condyle, and NWI as significant independent predictors for PCLIT and (2) MTD and NWI for PCLAF. The areas under the curve combining the 4 indicators for PCLIT and noncontact PCLIT were 0.79 (95% CI, 0.72-0.86) and 0.90 (95% CI, 0.85-0.96), respectively. The area under the curve for the combination of MTD and NWI for PCLAF was 0.78 (95% CI, 0.70-0.86). Conclusion: Decreased MTD and NWI were associated with an increased incidence of PCLIT and PCLAF. Increased asymmetry of the medial and lateral slopes and the radius of the posterior circle of the medial femoral condyle were associated with the presence of PCLIT. In addition, the model of a combination of risk factors showed good predictive ability for noncontact PCLIT. These findings may aid clinicians in identifying patients at risk for PCL lesions. Further studies are warranted for identifying the effect of these factors on biomechanical mechanisms.

Steeper lateral posterior tibial slope and greater lateral-medial slope asymmetry correlate with greater preoperative pivot-shift in anterior cruciate ligament injury

PurposeTo investigate the association between posterior tibial slope (PTS) and preoperative pivot-shift phenomenon in anterior cruciate ligament (ACL)-injured knees.MethodsFifty unilateral ACL-injured patients (mean age: 28.0 ± 11.4 years, 29 males) who underwent ACL reconstruction were retrospectively included. Patients with a history of injury to the ipsilateral knee joint, concomitant ligament injuries with ACL injury, and/or more than one year from injury to surgery, were excluded. Pivot-shift tests were performed preoperatively under general anaesthesia using an electromagnetic measurement system, and tibial acceleration (m/s2) during the posterior reduction of the tibia was measured. Medial and lateral PTS (°) were measured respectively using high-resolution CT images taken two weeks after surgery. Lateral-medial slope asymmetry was calculated by subtracting medial PTS from lateral PTS (lateral-medial PTS) and we evaluated the correlation between each PTS parameter (medial PTS, lateral PTS, and lateral-medial slope asymmetry) and tibial acceleration during the pivot-shift test. The level of significance was set at p < 0.05.ResultsMedial PTS was 4.9 ± 2.0°, and lateral PTS was 5.2 ± 1.9°. The lateral-medial slope asymmetry was 0.3 ± 1.6° (range: -2.9 to 3.8). Tibial acceleration during the pivot-shift test in the ACL-injured knee was 1.6 ± 0.1 m/s2. Preoperative tibial acceleration was positively correlated with lateral PTS (r = 0.436, p < 0.01), and lateral-medial slope asymmetry (r = 0.443, p < 0.01), while no significant correlation was found between preoperative tibial acceleration and medial PTS (r = 0.06, p = 0.70).ConclusionPreoperative greater tibial acceleration during the pivot-shift test was associated with steeper lateral PTS and greater lateral-medial slope asymmetry in ACL-injured knees. These findings improve our understanding of anterolateral rotatory knee laxity by linking tibial bony morphology to quantitative measurement of pivot-shift phenomenon. Surgeons should be aware that not only lateral PTS but also lateral-medial slope asymmetry are the factors associated with preoperative pivot-shift.Level of EvidenceLevel IV.

Association of Elevated Posterior Tibial Slope With Revision Anterior Cruciate Ligament Graft Failure in a Matched Cohort Analysis

Background: Elevated posterior tibial slope (PTS) has been identified as an important risk factor in anterior cruciate ligament (ACL) injuries and ACL graft failures. The cutoff value to recommend treatment with slope-reducing osteotomy remains unclear and is based on expert opinion and small case series. Purpose: (1) To determine whether there is a difference in PTS shown on lateral knee radiographs and magnetic resonance imaging (MRI) scans in a group of patients who experienced revision ACL graft failure versus a control group of patients who underwent successful revision ACL reconstruction, (2) to identify cutoff values of PTS measurements that predict risk of revision ACL graft failure, and (3) to examine whether there is a correlation between radiographic and MRI measurements of PTS. Study Design: Case-control study; Level of evidence, 3. Methods: A total of 38 patients who experienced revision ACL graft failure were identified from a revision ACL database. These patients were matched 1:1 by age, sex, and graft type to a group of 38 control patients who underwent revision ACL reconstruction with no evidence of graft failure at a minimum 2 years of follow-up. Medial and lateral PTS were measured by lateral knee radiographs and MRI scans of the affected limb. Demographics, surgical characteristics, and PTS were compared between the groups. The optimal cutoff values of medial and lateral PTS per radiographs and MRI scans for predicting increased risk of revision ACL graft failure were determined by receiver operating characteristic curves. Conditional multivariable logistic regression was used to assess the relative contribution of PTS cutoff values as a predictor of revision graft failure. Results: The mean PTS values in the failure group were significantly higher than those in the control group on radiographs (medial, 13.2°± 2.9° vs 10.3°± 2.9°; P < .001; lateral, 12.9°± 3.0° vs 9.8°± 2.8°; P < .001) and MRI scans (medial, 7.2°± 3.1° vs 4.8°± 2.9°; P < .001; lateral, 8.4 ± 3.1° vs 5.9 ± 3.0°; P < .001). A radiographic medial PTS ≥14° had the highest increased risk of revision ACL graft failure with sensitivity equal to 50% and specificity to 92.1% (odds ratio, 18.71; 95% CI, 2.0-174.9; P = .01). Conclusion: Elevated PTS was a significant risk factor for revision ACL graft failure. Patients with radiographic medial PTS ≥14° had 18.7-times increased risk of revision ACL failure.

The prevalence of fabella and its relationship with the lateral posterior condylar offset and lateral posterior tibial slope values.

This study aims to analyze whether the lateral posterior condylar offset (LPCO) and lateral posterior tibial slope (LPTS) values are associated with the presence of fabella by evaluating the frequency of fabella, its location, and whether it is bilateral and the relationship of the fabella with age, sex, and the presence of osteoarthritis. Between January 2016 and December 2020, computed tomography (CT) scans including 1,952 knee regions of 1,220 patients (861 males, 359 females; mean age: 54.5±19.7 years; range, 10 to 98 years) were retrospectively analyzed. Age, sex, and the presence of fabella whether unilateral (left or right) or bilateral were recorded. Of the patients with a bilateral knee CT, those with fabella on one side and without on the other were studied further to investigate the effect of fabella on the posterolateral corner (PLC). In these patients, the LPCO and LPTS values, presence of knee osteoarthritis, fabella-femoral distance, and sagittal anterior-posterior diameter of the fabella were evaluated. While there was no evidence of fabella in 867 (71.1%) patients, it was present in 353 (28.9%) patients. The linear correlation analysis revealed that the correlations between the right LPCO and the right LPTS (r=-0.295; p<0.001) and between the left LPCO and the left LPTS (r=-0.574; p<0.001) were significant. It was observed that LPTS decreased with increasing LPCO. According to the results of the point biserial correlation analysis, there was a significant correlation between the presence of fabella on the right side and the right LPCO value (r=-0.643; p<0.001) and between the presence of fabella on the left side and the left LPCO (r=-0.284; p=0.024). When the two knees were compared, fabella was less present in the knee whose LPCO was higher than that of the other knee, whereas it was more common in the knee whose LPCO was lower than that of the other knee. We found a significant correlation between each side's fabella and LPCO values and between the presence of fabella on the left side and the left LPTS. The presence of fabella in the knee joint may be associated with LPCO and LPTS values of the knee. The comparison of the two knees of the same patient may reveal that if a fabella is present in a knee, the LPCO value of that knee is lower than that of the other knee. We believe that the reason for this is that the presence of fabella increases the distance to the center of rotation of the knee joint.

Lateral posterior tibial slope does not affect femoral but does affect tibial tunnel widening following anatomic anterior cruciate ligament reconstruction using a Bone–Patellar Tendon–Bone graft

BackgroundTunnel widening (TW) after anterior cruciate ligament (ACL) reconstruction has been a research area of interest in ACL reconstruction. In recent years, it has been noted that posterior tibial slope (PTS) affects several types of outcomes after ACL reconstruction including TW. However, the relationships between femoral and tibial TW and between PTS and TW following anatomical ACL reconstruction using a bone–patellar tendon–bone (BTB) graft are often not understood. Therefore, the purpose of this study was to retrospectively clarify the magnitude of femoral and tibial TW and the effect of PTS on TW following anatomical ACL reconstruction using a BTB graft. MethodsA total of 111 patients who underwent isolated ACL reconstructions using BTB grafts were included in this study. Femoral and tibial tunnel aperture areas were measured using three-dimensional computed tomography (3D CT) at 1 week and 1 year postoperatively, and femoral and tibial TW (%) was calculated. Lateral and medial PTS was also measured using 3D CT. ResultsAs compared with 1 week postoperatively, the mean tibial tunnel aperture areas increased by 30.6% ± 28.5%, and the mean femoral tunnel aperture areas increased by 28.3% ± 27.9% when measured at 1 year postoperatively. Although no significant difference was observed between femoral and tibial TW, a significant positive correlation was noted between femoral and tibial TW (r = 0.240, p = 0.011). A significant correlation was observed only between lateral PTS and tibial TW (r = 0.354, p < 0.001). There was no significant correlation between medial PTS and tibial TW, lateral PTS and femoral TW, or medial PTS and femoral TW. ConclusionSignificant positive correlation was observed between femoral and tibial TW. Steeper lateral PTS correlated with greater tibial TW; on the other hand, medial PTS did not correlate with tibial TW. Although lateral PTS affected tibial TW, it did not affect femoral TW.

Meniscal Bone Angle Is a Strong Predictor of Anterior Cruciate Ligament Injury

To evaluate the influence of lateral posterior tibial slope (LPTS) and meniscal bone angle (MBA) on primary anterior cruciate ligament (ACL) tear risk in an adult population through the LPTS-MBA ratio. A retrospective case-control study was performed with patients from a tertiary hospital who underwent primary ACL surgery and had preoperative magnetic resonance imaging (MRI). These subjects were matched by age and sex in a 1:1 ratio to patients who had an MRI without ACL tear. LPTS and MBA were measured on MRI scan. Quantitative data are presented in the median ± interquartile range (IQR). Identification of independent risk factors for primary ACL tear was performed using multivariable logistic regression. Receiver operating characteristics curves detected any variable with strong discriminative capacity. In total, 95 patients with primary ACL tear confirmed on MRI were matched with 95 controls (N= 190). Nearly 80% were male subjects, with a median age of 26 years. In the ACL tear group, the median value of LPTS-MBA ratio was 0.20 (IQR 0.11-0.37) versus 0.12 (IQR 0.08-0.19) in the control group (P= .001). LPTS had a median value of 4.20° in the ACL tear group (IQR 2.05-7.35°) and 2.90° in the control group (IQR, 2.05-5.00°) (P= .026), whereas MBA was 19° (IQR, 16-24°) versus 26° (IQR, 24-30°) (P= .001), respectively. Logistic regression showed that LPTS (odds ratio 1.20, 95% confidence interval 1.03-1.42, P= .021) and MBA (odds ratio 0.78, 95% confidence interval 0.71-0.85, P= .001) were independent predictors. The area under the curve (AUC) of LPTS-MBA ratio was 0.69, greater than that of LPTS alone (AUC= 0.61) but lower than that for MBA (AUC= 0.82). In this study, a reduced MBA was the strongest predictive variable associated with a primary ACL tear. A threshold of 22.35° of MBA was associated with an increased risk of ACL tear, with a sensitivity of 70% and specificity of 84%. A cut-off of 0.22 of LPTS-MBA was associated with an increased risk of ACL tear, with a sensitivity of 55% and specificity of 87%. Level III, case-control study.

Is Posterior Tibial Slope and Mechanism of Failure Crucial for an Anatomically Reconstructed Primary Hamstring Graft Anterior Cruciate Ligament?

Purpose Native anterior cruciate ligament (ACL) failure is multifactorial with tibial slope identified as a crucial risk factor. The aim was to examine relation between lateral posterior tibial slope (LTPS) and failed ACL primary reconstruction by negating the associated risk factors such as tunnel position, gender, and graft types based on the mechanism of failure. Materials and Methods Our retrospective study included 102 patients, diagnosed as failed primary anterior cruciate ligament reconstruction (ACLR). The LPTS was measured on lateral radiographs and the tunnel position assessed by magnetic resonance imaging on both femoral, tibial side by two musculoskeletal radiologists. We compared the slopes in patients based on their mechanism of failure. Results The mean LPTS in patients with anatomically placed tunnel (9.28° ± 3.5°; range, 4°–18°) was significantly higher than the rest (7.7° ± 2.9°; range, 3°–15°; P = 0.01). There was a significant association of higher tibial slope in graft rupture due to contact mechanism of failure (P = 0.02). LPTS was not significantly associated with noncontact mechanism of failure. Conclusion LTPS is a significant risk factor for failure in hamstring graft reconstructed ACL patients with optimally placed tunnels. LPTS ≥10° increases the risk of hamstring graft failure due to contact mechanism.

Posterior tibial slope and meniscal slope correlate with in vivo tibial internal rotation during running and drop jump.

The relationship between tibial bony and meniscus anatomy and knee kinematics during in vivo, high-impact activities remains unclear. This study aimed to determine if the posterior tibial slope (PTS) and meniscal slope (MS) are associated with in vivo anterior-posterior translation and internal tibia rotation during running and double-leg drop jumps in healthy knees. Nineteen collegiate athletes performed fast running at 5.0m/s on an instrumented treadmill and double-leg drop jump from a 60cm platform while biplane radiographs of the knee were acquired at 150Hz. Tibiofemoral kinematics were determined using a validated model-based tracking process. Medial and lateral PTS and MS were measured using magnetic resonance imaging (MRI). In fast running, more internal tibia rotation was associated with greater PTS (ρ = 0.336, P = 0.039) and MS (ρ = 0.405, P = 0.012) in the medial knee compartment. In the double-leg drop jump, more internal tibia rotation was associated with greater PTS (ρ = 0.431, P = 0.007) and MS (ρ = 0.323, P = 0.005) in the medial knee compartment, as well as a greater PTS in the lateral knee compartment (ρ = 0.445, P = 0.005). These findings suggest that the medial and lateral PTS and medial MS are associated with the amount of knee rotation during high-impact activities. These in vivo findings improve our understanding of ACL injury risk by linking bone and meniscus morphology to dynamic kinematics.

The role of lateral and medial posterior tibial slope in anterior cruciate ligament injuries: a case-control study

&lt;p&gt;&lt;strong&gt;Background: &lt;/strong&gt;The anterior cruciate ligament (ACL) is one of the major stabilisers of the knee and is the most frequently involved ligament in knee injuries and related functional instability. The objective of the study was to compare the lateral posterior tibial slope (LPTS) and medial posterior tibial slope (MPTS) among those with ACL injury and those with the intact ligament.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Methods:&lt;/strong&gt; MRI of 65 (male-43, female-22) ACL injured and 65 (male-58, female-7) ACL intact knees were studied. Using RadiAnt DICOM viewer software, the slopes of both medial and LPTS s were measured. The statistical analysis was performed by IBM SPSS 25. Associations between various factors were assessed using the Chi square test for categorical variables and independent t test were done for quantitative variables. P&amp;lt;0.05 had been considered statistically significant.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Results: &lt;/strong&gt;Among cases the mean LPTS was 10.23&lt;sup&gt;0&lt;/sup&gt;±3.93&lt;sup&gt;0&lt;/sup&gt; and mean MPTS was 6.61&lt;sup&gt;0&lt;/sup&gt;±3.49&lt;sup&gt;0&lt;/sup&gt;. Among controls, mean LPTS was 8.46&lt;sup&gt;0&lt;/sup&gt;±3.63&lt;sup&gt;0&lt;/sup&gt;, mean MPTS was 5.51&lt;sup&gt;0&lt;/sup&gt;±2.91&lt;sup&gt;0&lt;/sup&gt;. Case had a statistically significant (p=0.009) steeper LPTS than control population. MPTS of cases were steeper than the control population with no statistical significance (p=0.055).&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Conclusions:&lt;/strong&gt; In this study, the LPTS was significantly increased among patients with ACL injury as compared with ligament-intact controls. LPTS measurements should be considered as a significant independent modifiable risk factor for ACL injury.&lt;/p&gt;