Blumensaat's Line Research Articles

The Effect of C-Arm Position on Femoral Tunnel Placement in Medial Patellofemoral Ligament Reconstruction

Background: Medial patellofemoral ligament (MPFL) reconstruction is a common treatment for patellar instability. Yet nearly 40% of revisions result from femoral tunnel misplacement. One reason may be the positioning of the C-arm relative to the knee. Purpose: To assess how the C-arm’s position affects femoral MPFL placement when the image receptor is positioned either contralateral or ipsilateral to the operated knee. Study Design: Controlled laboratory study. Methods: Ten human cadaveric knee specimens were dissected, and the femoral MPFL insertion site was identified and marked using a 10-mm eyelet. According to the possible clinical scenarios, true lateral radiographs in 2 different C-arm positions were taken. In the first scenario, the image receptor was on the ipsilateral side, being 5 cm away from the knee with the x-ray beam directed from medial to lateral (ML5). In the second scenario, the image receptor was on the contralateral side, being 25 cm away from the knee with the x-ray beam directed from lateral to medial (LM25). In each radiograph, the eyelet position was recorded and the distance (proximal-distal and anterior-posterior) from the optimal radiographic insertion point according to the literature was determined. Differences between the groups were calculated using the Wilcoxon signed-rank test, and a P value of <.05 was considered significant. Results: The anatomic femoral MPFL insertion in the ML5-position was located a mean of 2.7 ± 2.4 mm proximal and 4.5 ± 5.5 mm anterior to the Schöttle point. This resulted in an absolute distance of 7.2 ± 3.0 mm. In the LM25-position, it was located a mean of –0.7 ± 1.8 mm distal and 3.0 ± 5.3 mm anterior, which resulted in an absolute distance of 5.4 ± 3.2 mm. The ML5 was located more anterior (1.5 ± 2.1 mm) and proximal (3.4 ± 2.4 mm) compared with the LM25 position. Measurements following methods described in the literature significantly differed in both axes in the LM25 view when compared with the ML5 view measurements ( P = .005). Conclusion: Compared with the ipsilateral C-arm position (ML5), the contralateral C-arm position (LM25) showed a smaller range with a lower standard deviation in identifying the femoral MPFL approach across all measurement methods. Clinical Relevance: When applying the method according to Schöttle et al to locate the femoral MPFL insertion point, it should be noted that in the proximal-distal orientation, the femoral MPFL insertion point is situated proximal to the Blumensaat line in the contralateral view (LM25). In contrast, when using the ipsilateral view (ML5), the femoral MPFL footprint is positioned just distal to the proximal edge of the medial condyle.

Lateral femoral impaction fractures during an ACL tear extend posteriorly on the weight-bearing area of the tibiofemoral joint.

Posterior elongation of the physiological terminal sulcus (TS) due to lateral femoral condyle impaction fracture (LFC-IF) after an anterior cruciate ligament (ACL) tear could potentially decrease the weight-bearing area of the tibiofemoral joint, decrease the tension on lateral meniscus and cause flattening of the LFC which would influence rotational knee motion and cause anisometry of the lateral and anterolateral stabilizers. Therefore, the purpose of the study was to assess if the LFC-IF elongates the physiological TS posteriorly. One hundred patients magnetic resonance images (MRIs) (75 males, 25 females, mean age 32.2 years, SD = 8.2) were included with a 1:1 ratio between the full-thickness ACL tear group and the control group (patients with knee MRI performed due to other reasons, with no tear of ACL on MRI and negative clinical tests). Two independent raters evaluated the sagittal T1-weighted preselected MRI scans. The principal measurement of interest was the distance from the intersection of the Blumensaat line with subchondral bone to the posterior border of the TS/LFC-IF. The median distance from the Blumensaat line to the posterior border of the TS/LFC-IF was significantly higher in the ACL tear group: 14.3 mm, interquartile range (IQR) = 11.6-16.4 mm versus control group: 12.8 mm, IQR = 9.0-15.0 mm, p = 0.038. Intrarater and inter-rater reliabilities were >0.90. LFC-IF after full-thickness ACL tear significantly elongates the physiological TS in the posterior direction. Level III.

Evaluation of the Angle Between the Long Axis of the Femoral Anterior Cruciate Ligament Footprint and Bony Morphology of the Knee: A Cadaveric Descriptive Study.

There have been numerous studies of the anterior cruciate ligament (ACL) anatomy, but few have focused on the long axis angle of the femoral ACL footprint. This study investigated the angle between the long axis of the femoral ACL footprint and the bony morphology of the knee. This study is a cadaveric descriptive study. Thirty non-paired formalin-fixed knees of Japanese cadavers were used. Anteromedial (AM) and posterolateral (PL) bundles were identified according to the tension pattern differences during the complete range of motion of the knee. In the ACL femoral footprint, there is a fold between the mid-substance insertion site and fan-like extension fibers. After identifying AM and PL bundles of mid-substance fibers, the mid-substance and fan-like extension fibers were divided into those bundles and stained. We defined the line passing through the center of the AM and PL bundles as the long axis of the ACL. The center points of each of the four areas and the angle between the long axis of the ACL and the bony morphology of the knee were calculated using Image J software. The mean angle between the axis of the femoral shaft and the long axis of the ACL mid-substance insertion was 28.8 ± 12.2degrees. The mean angle between the Blumensaat line and the long axis of the mid-substance was 54.2 ± 13.5degrees. The mean angle between the axis of the femoral shaft and the long axis of the femoral ACL footprint was approximately 29degrees. There is a wide variation in the long axis of the femoral ACL footprint. To achieve better clinical results through a more anatomically accurate reconstruction, it can be beneficial to replicate the ACL femoral footprint along its native long axis.

Femoral Tunnel Position in Anatomical Double-bundle ACL Reconstruction is not Affected by Blumensaat's Line Morphology.

The aim of this study was to reveal the influence of the morphological variations of the Blumensaat's line on anteromedial (AM) and posterolateral (PL) femoral tunnel position in anatomical double-bundle anterior cruciate ligament (ACL) reconstruction.Fifty-three subjects undergoing anatomical double-bundle ACL reconstruction were included (29 female, 24 male; median age 27.4 years; range: 14-50 years). Using an inside-out transportal technique, the PL tunnel position was made on a line drawn vertically from the bottommost point of the lateral condyle at 90 degrees of knee flexion, spanning a distance of 5 to 8 mm, to the edge of the joint cartilage. AM tunnel position was made 2 mm distal to the PL tunnel position. Following Iriuchishima's classification, the morphology of the Blumensaat's line was classified into straight and hill (large and small) types. Femoral tunnel position was determined using the quadrant method. A Mann-Whitney U test was performed to compare straight and hill type knees according to AM and PL femoral tunnel position.There were 18 straight and 35 hill type knees (13 small and 22 large hill). AM and PL femoral tunnel position in straight type knees were 21.7 ± 7.0 and 33.6 ± 10.5% in the shallow-deep direction, and 42.1 ± 11.1 and 72.1 ± 8.5% in the high-low direction, respectively. In hill type knees, AM and PL femoral tunnel position were 21.3 ± 5.8 and 36.9 ± 7.1% in the shallow-deep direction, and 44.6 ± 10.7 and 72.1 ± 9.7% in the high-low direction, respectively. No significant difference in AM or PL femoral tunnel position was detected between straight and hill type knees.AM and PL femoral tunnel position in anatomical double-bundle ACL reconstruction was not affected by the morphological variations of the Blumensaat's line. Surgeons do not need to consider Blumensaat's line morphology if AM and PL femoral tunnel position is targeted at the bottommost point of the lateral condyle. This was a level of evidence III study.

Is Blumensaat Inclination Angle (BIA) and Angle between Blumensaat line and Tibal Slope (BATS) a Risk Factor for ACL Injury?

Is Blumensaat Inclination Angle (BIA) and Angle between Blumensaat line and Tibal Slope (BATS) a Risk Factor for ACL Injury?

Radiographic Landmark Measurements for the Femoral Footprint of the Medial Patellofemoral Complex May Be Affected by Visible Femoral Shaft Length on Lateral Knee Radiographs

To assess the effect of visible femoral shaft length on the accuracy of radiographic landmarks of the medial patellofemoral complex (MPFC). In 9 cadaveric knees, the MPFC footprint was exposed on the medial femur, and its proximal and distal boundaries were marked. Lateral fluoroscopic images of the knee were assessed in 1-cm length increments, beginning 1 cm proximal to the medial condyle and continuing proximally to 8 cm. The MPFC midpoint was described on each image relative to the posterior cortical line of the femur and a line perpendicular to this line through the proximal margin of the medial condyle. In addition, the MPFC midpoint was assessed relative to a line from the proximal posterior cortex to the midpoint of Blumensaat line. Using the posterior cortical line as a reference, the MPFC radiographic landmark moved anteriorly with decreasing visible femoral shaft on radiographs, particularly at 4 cm and less. However, no proximal-distal change was noted. Linear regression analysis demonstrated a relationship between visible femoral shaft and MPFC position on radiographs (R= 0.461, R2= 0.212, B= -0.636, P < .001). For every centimeter decrease in the visible femoral shaft, the radiographic MPFC footprint moved anteriorly by 0.636 mm. Receiver operating characteristic curve analysis revealed that a minimum of 4 cm of femoral shaft on lateral radiographs is required for accurate MPFC footprint localization (area under the curve= 0.80; sensitivity= 76.7%; specificity= 69.0%; P < .001). In contrast, no anterior-posterior change was seen when referencing a line from the proximal posterior cortex to the midpoint of Blumensaat line. When using the posterior cortical line to identify the midpoint of the MPFC, at least 4 cm of femoral shaft should be visible for accurate assessment. If less than 4 cm of shaft is visible, a line through the midpoint of Blumensaat line and the proximal posterior cortex can be used as an alternative method to estimate the position of the femoral footprint. As fluoroscopy is frequently used intraoperatively for MPFC reconstruction, our findings may serve as a guide when assessing femoral tunnel placement on fluoroscopy.

Femoral Tunnel Length in Anatomical Double-Bundle Anterior Cruciate Ligament Reconstruction Is Correlated with Body Size and Knee Morphology.

The purpose of this study was to reveal the correlation between anteromedial (AM) and posterolateral (PL) femoral tunnel lengths in anatomical double-bundle anterior cruciate ligament (ACL) reconstruction and body size and knee morphology. Thirty-four subjects undergoing anatomical double-bundle ACL reconstruction were included in this study. Preoperative body size (height, body weight, and body mass index) was measured. Using preoperative magnetic resonance imaging (MRI), quadriceps tendon thickness and the whole anterior-posterior length of the knee were measured. Using postoperative computed tomography (CT), axial and sagittal views of the femoral condyle were evaluated. The correlation between measured intraoperative AM and PL femoral tunnel lengths, and body size and knee morphology using preoperative MRI and postoperative CT parameters was statistically analyzed. Both AM and PL femoral tunnel lengths were significantly correlated with height, body weight, posterior condylar length, and Blumensaat's line length. These results suggest that the femoral ACL tunnel length created using a transportal technique can be estimated preoperatively by measuring the subject's body size and/or the knee morphology using MRI or CT. For clinical relevance, surgeons should be careful to create femoral tunnel of sufficient length when using a transportal technique, especially in knees of subjects with smaller body size and knee morphology. Level of evidence is III.

Can the ACL Cross-Sectional Area Be Predicted? Size Correlation and Proportion between the ACL Cross-Sectional Area and the Femoral Intercondylar Notch Area.

The purpose of this study was to reveal the correlation and proportion between the anterior cruciate ligament (ACL) cross-sectional area and the femoral intercondylar notch area. Sixty-three subjects (33 female and 30 male) less than 50 years old were included in this study. All subjects complained of knee pain, although magnetic resonance imaging (MRI) showed no structural damage of the knee. Using the T2 axial slice of the MRI perpendicular to the bone shaft, the ACL cross-sectional area and the femoral intercondylar notch area were measured. Measurements were made at the most proximal (S1), ⅓ (S2), ⅔ (S3), and the most distal (S4) Blumensaat's line levels. The correlation and the proportion between the ACL cross-sectional area and the notch area were calculated. The ACL cross-sectional area was: S1: 35.9 ± 10mm2, S2: 59.9 ± 14mm2, S3: 67.2 ± 19.5mm2, and S4: 70.7 ± 20.3mm2. The notch area was: S1: 215.5 ± 43mm2, S2: 311.8 ± 65mm2, S3: 453.8 ± 86mm2, and S4: 503.7 ± 99.8mm2. The ACL cross-sectional area and the notch area were found to be significantly correlated at the S3 (Pearson's coefficient correlation: 0.510, p = 0.000) and S4 (Pearson's coefficient correlation: 0.529, p = 0.000) levels. The proportion of the ACL cross-sectional area to the notch area was 15% in S3 and 14% in S4. The ACL cross-sectional area was found to be significantly correlated with the femoral intercondylar notch area at the distal level of the Blumensaat's line. The ACL cross-sectional area was found to be approximately 15% of the notch area. The ACL cross-sectional area can be predicted by measuring the femoral intercondylar notch area. This finding can be useful for achieving greater accuracy in anatomical ACL reconstruction. LEVEL OF EVIDENCE: III.

Correlation between spatial inclination of Blumensaat line and anterior cruciate ligament injury based on EOS biplanar 3D imaging system

To explore correlation between femoral mechanical axis and Blumensaat line (FMBL) angle of knee joint (angle between Blumensaat line and femoral mechanical axis), α angle (angle between Blumensaat line and axis of distal femur in sagittal plane) on EOS biplane imaging and non-contact anterior cruciate ligament(ACL) injury, and evaluate angle for its accuracy in predicting the populations prone to non-contact ACL injury. From February 2018 to October 2020, EOS imaging and clinical data from 88 patients (176 knees) with unilateral non-contact ACL injury were retrospectively analyzed, including 53 males and 35 females, aged from 18 to 45 years old with an average of (30.3±6.2) years old, 48 patients on the left side and 40 patients on the right side. The patients were divided into ACL-affected group and ACL-health group according to side of ACL injuries, and 51 patients (51 knees) with non-ACL identified from EOS database were included in normal control group, including 28 males and 23 females, aged from 20 to 44 years old with an average of (31.6±5.5) years old, 26 patients on the left side and 25 patients on the right side. Full-length EOS imaging of skeleton extremitatis inferioris among three groups were reconstructed to 3D images of skeletal system with EOS software, and then FMBL angle and α angle were measured on the images. Univariate binary Logistic regression analysis was performed to determine the influence of the univariate(FMBL angle or α angle) on ACL status(normal or torn). And the angle cutoff value for univariate was selected based on receiver operating characteristics curve (ROC) to got the best accuracy. There was no statistically significant difference in age, gender and side distribution between ACL-injured group and normal control group(P>0.05). Statistical analyses (one-way ANOVA) indicated no significant difference in FMBL angle between ACL-injured knee group (32.8±2.3)° and ACL-injured contralateral knee group(32.5±2.3)°(P>0.05), but the values between two groups were significantly lower than that in normal control group (37.0±2.0)°(P<0.001). There was no statistically significant difference in α angle among three groups (P>0.05). Univariate binary Logistic regression analysis demonstrated that FMBL angle was risk factor for non-contact ACL injury[OR=0.433, 95%CI(0.330, 0.569), P<0.001]. The area under ROC curve for FMBL angle was 0.909[95%CI(0.861, 0.958), P<0.001], and the sensitivity and specificity were 70.5% and 98.0% respectively, cut-off value was 33.7°. FMBL angle formed by Blumensaat line and femoral mechanical axis is one of the risk factors for non-contact ACL injury and has good predictive accuracy. The general population with FMBL angle below 33.7° may be increased risk for ACL injury.

Patient-Individualized Identification of Medial Patellofemoral Ligament Attachment Site to Femur Using "CLASS" MRI Sequences.

Malposition of the femoral tunnel during medial patellofemoral ligament (MPFL) reconstruction may increase the risk of recurrence of patellar dislocation due to isometric changes during flexion and extension. Different methods have been described to identify the MPFL isometric point using fluoroscopy. However, femoral tunnel malposition was found to be the cause of 38.1% of revisions due to patellar redislocation. This high rate of malposition has raised the question of individual anatomical variability. Magnetic resonance imaging (MRI) was performed on 80 native knees using the CLASS (MRI-generated Compressed Lateral and anteroposterior Anatomical Systematic Sequence) algorithm to identify the femoral MPFL insertion. The insertions were identified on the MRI views by 2 senior orthopaedic surgeons in order to assess the reliability and reproducibility of the method. The distribution of the MPFL insertion locations was then described in a 2-plane coordinate system and compared with MPFL insertion locations identified with other methods in previously published studies. The CLASS MPFL footprint was located 0.83 mm anterior to the posterior cortex (line 1) and 3.66 mm proximal to the Blumensaat line (line 2). Analysis demonstrated 0.90 and 0.89 reproducibility and 0.89 and 0.80 reliability of the CLASS method to identify the anatomical femoral MPFL insertion point. The distribution did not correlate with previously published data obtained with other methods. The definitions of the MPFL insertion point in the studies by Schöttle et al. and Fujino et al. most closely approximated the CLASS location in relation to the posterior femoral cortex, but there were significant differences between the CLASS method and all 4 previously published methods in relation to the proximal-distal location. When we averaged the distances from line 1 and line 2, the method that came closest to the CLASS method was that of Stephen et al., followed by the method of Schöttle et al. The CLASS algorithm is a reliable and reproducible method to identify the MPFL femoral insertion from MRI views. Measurement using the CLASS algorithm shows substantial individual anatomical variation that may not be adequately captured with existing measurement methods. While further research must target translation of this method to clinical use, we believe that this method has the potential to create a safe template for sagittal fluoroscopic identification of the femoral tunnel during MPFL surgical reconstruction. Prognostic Level II. See Instructions for Authors for a complete description of levels of evidence.

Ideal Anchor Points for Patellar Anti-rotational Sutures for Management of Medial Patellar Luxation in Dogs: A Radiographic Survey.

The aim of this study was to identify the ideal anchor point for patellar anti-rotational sutures for adjunctive stabilization of medial patellar luxation in both small and large breed dogs. Retrospective radiographic survey was performed on 110 stifles from 101 dogs. Radiographs were grouped based on patient weight (≤15 kg; >15 kg) and diagnosis (medial patellar luxation, cranial cruciate ligament rupture, and normal joints). Radiographic measurements included: the proximal, middle, and distal points of the trochlear ridge, the caudal aspect of Blumensaat's line (roof of the intercondylar notch), the centre of the lateral fabella, as well as the "best-fit" centre of a circle overlying the trochlea. These landmark coordinates were used to calculate radii for comparison, and for scaling between joints. Use of the fabellar centre resulted in larger radii (corrected p <0.001) than those from the best-fit circle centre for all but one combination of patient group and trochlear end point locations. Using the best-fit circle centre, radius variation was less marked than with the fabellar centre. Significant differences in location for centres of the best-fit circle and fabella were seen across all patient categories (Pillai's trace p <0.001). The fabella is unlikely to be the best choice for anchoring a patellar anti-rotational suture. Use of the best-fit circle centre to place a suture anchor should be preferred to maximise suture isometry during joint flexion and extension in large and small breed dogs.

Anteromedial Portal versus Transtibial Drilling Techniques for Femoral Tunnel Placement in Arthroscopic Anterior Cruciate Ligament Reconstruction: Radiographic Evaluation and Functional Outcomes at 2 Years Follow-Up.

The aim of this study was to compare the functional and radiographic outcomes of arthroscopic single-bundle anterior cruciate ligament reconstruction (ACLR) using either the anteromedial (AM) portal technique or transtibial (TT) technique. We identified 404 patients who underwent arthroscopic ACLR by a single surgeon between January 2006 and December 2016 at our institution. The TT portal was utilized in femoral tunnel drilling in 202 patients (TT group) while the AM portal was used in 202 patients (AM group). The mean postoperative follow-up duration was 26 months (range: 24-33 months). Postoperative radiographic femoral and tibial tunnel positions were assessed by two independent observers. Functional outcomes were evaluated with Tegner, Lysholm, and Knee Injury and Osteoarthritis Outcome score (KOOS) scores. On the anteroposterior plain radiographs, the mean femoral tunnel position relative to the lateral femoral condyle was 46.8% for the AM group versus 48.6% in the TT group, respectively (p=0.003). The mean graft inclination angle was 31.9° and 22° in the AM and TT groups, respectively (p<0.0001). On the lateral radiographs, the mean femoral tunnel placement across Blumensaat's line in relation to the anterior femoral cortex was 84% in the AM group while it was 78% in the TT group (p<0.0001). At 2 years postoperatively, there were no significant differences in the mean Tegner, Lysholm, and KOOS scores between the two patient groups. The graft failure rate at 2 years follow-up was 4.5% (n=9) in the AM group while it was 2.5% (n=5) in the TT group (p=0.2). Femoral tunnel placement was more anatomical with the AM portal technique compared with the TT technique. However, there was no significant difference in postoperative functional outcomes between the two patient groups. The AM portal technique appears to have a higher graft failure rate. This might be attributed to increased graft loading in an anatomical position.

Computer-assisted navigation in ACL reconstruction improves anatomic tunnel placement with similar clinical outcomes

BackgroundWhile the use of navigation systems in anterior cruciate ligament (ACL) reconstruction theoretically improves tunnel placement accuracy and clinical outcomes, the existing literature remains inconclusive. We aimed to evaluate the potential benefits of navigated ACL reconstruction on tunnel placement and clinical outcomes. MethodsIn this retrospective study, we evaluated a cohort of patients who underwent conventional or navigated (OrthoPilot system) primary ACL reconstruction at our institution from June 2004 to October 2009. Anteroposterior and lateral radiographic knee assessments were evaluated to assess postoperative tunnel positioning. Clinical outcomes, including the International Knee Documentation Committee classification, Lysholm score, and Tegner score, were evaluated preoperatively and 1-year postoperatively. Radiographic and clinical outcomes were compared and analysed using independent 2-sample t-tests and Chi-square tests. ResultsSixty patients met the inclusion criteria and were included for analysis, comprising of 26 navigated and 34 conventional reconstructions. Postoperative radiographs showed no differences in tibial tunnel position between both groups, but a significantly smaller deviation from the recommended position in the navigated group (navigated: 5.96 %; conventional: 7.92 %; p = 0.008). Femoral tunnel placements in the navigated group were significantly more perpendicularly away from the Blumensaat line (navigated: 38.90 %; conventional: 31.94 %; p = 0.001), with a greater deviation from recommended position (navigated: 11.00 %; conventional: 6.94 %; p = 0.009). There were no differences in 1-year postoperative clinical outcomes (p > 0.05). ConclusionNavigated ACL reconstruction resulted in a more anatomic femoral tunnel placement and similar clinical outcomes as conventional reconstruction. Further research should be conducted to clarify the potential biomechanical and clinical impacts of navigated ACL reconstruction.

Effect of Anterolateral Structure Augmentation on Graft Maturity After Anterior Cruciate Ligament Reconstruction: A Clinical and MRI Follow-up of 2 Years

Background: Anterolateral structure augmentation (ALSA) has been applied to prevent residual rotatory instability and lower clinical failure rates after anterior cruciate ligament (ACL) reconstruction (ACLR); however, the effect of combined ALSA on the maturity of ACL grafts remains unknown. Purpose: To evaluate the graft maturity and patient–reported outcomes in patients who underwent double–bundle ACLR with or without ALSA. Study Design: Cohort study; Level of evidence, 3. Methods: A total of 92 patients who underwent double–bundle ACLR between January 2016 and July 2019 were included in the present study—44 patients with isolated ACLR (ACLR group) and 48 patients with combined ACLR and ALSA (ALSA group). Demographic characteristics, intraoperative findings, and patient–reported outcomes were prospectively collected. On postoperative magnetic resonance imaging at the 2–year follow–up, the signal–to–noise quotient (SNQ) values were separately calculated for 6 sections of the ACL graft, including the femoral intratunnel graft (FTG), intra–articular graft (IAG), and tibial intratunnel graft (TTG) of the anteromedial bundle (AMB) and the posterolateral bundle (PLB). Superior graft maturity was usually indicated by lower SNQ values. Results: The rates of return to preinjury sports were 47.9% and 27.3% in the ALSA and ACLR groups, respectively (difference, 20.6% [95% CI, 1.3%-40%]; P = .042). The AMB demonstrated significantly lower SNQ values in the ALSA group than in the ACLR group (FTG, 7.04 ± 3.65 vs 9.44 ± 4.51 [P = .006]; IAG, 6.62 ± 4.19 vs 8.77 ± 5.92 [P = .046]; TTG, 6.93 ± 3.82 vs 8.75 ± 4.55 [P = .040]). The SNQ values were significantly lower in the ALSA group for 2 of the 3 sections of the PLB (IAG, 7.73 ± 4.61 vs 9.88 ± 5.61 [P = .047]; TTG, 5.88 ± 3.10 vs 8.57 ± 4.32 [P = .001]). Partial lateral meniscectomy was correlated with higher SNQ values of the TTG in the AMB (β = 0.27; P = .009) and the PLB (β = 0.25; P = .008), with both groups pooled. Higher body mass index, smaller ACL graft–Blumensaat line angles, larger AMB graft diameters, and lower postoperative Tegner scores were also associated with inferior maturity in specific regions of the ACL graft. Conclusion: A combination of ACLR and ALSA is a desirable option to improve the maturity of ACL grafts for patients who are young or expected to return to pivoting sports. Meanwhile, further investigations with higher levels of evidence and longer periods of follow–up are warranted.

Relationship Between Number of Lateral Intercondylar Ridges and Area of Denser Bone on the Lateral Intercondylar Wall.

Background:A deeper understanding of the anatomy of the intercondylar notch of the femur may help reduce technical errors during anatomic anterior cruciate ligament (ACL) reconstruction.Purposes:To classify the number of ridges on the lateral intercondylar wall, identify factors influencing the number of ridges, and define the relationship between the area of denser bone on the lateral intercondylar wall and the lateral intercondylar ridge.Study Design:Descriptive laboratory study.Methods:Included were 89 patients with computed tomography (CT) images of the knee joint. On full lateral view of the lateral femoral condyle, the authors evaluated for the presence of a lateral intercondylar ridge. The height and area of the lateral intercondylar wall (notch height and lateral notch area) and the length of Blumensaat line were calculated. Notch outlet length, axial notch area, notch width index, and transepicondylar length were also calculated using 3-dimensional CT. Maximum intensity projection was used to identify the area of denser bone on the femoral lateral intercondylar wall, and the relationship between this area and the lateral intercondylar ridge was investigated.Results:The lateral intercondylar ridge exhibited 3 types of morphological variations. The invisible type (no ridge) was observed in 20 knees (22.5%); the ridge type (1 ridge), in 23 knees (25.8%); and the plateau type (2 ridges), in 46 knees (51.7%). There were significant differences in notch height, lateral notch area, Blumensaat line length, and denser bone area among the ridge types (P ≤ .031 for all). The locations of the anterior ridge of the plateau type and of all 23 ridges of the ridge type corresponded to the anterior margin line of the area of denser bone.Conclusion:Significant differences were seen in the 3 types of lateral intercondylar ridges. The anterior margin line of the denser bone area on the lateral intercondylar wall was found to correspond to the anterior border of the plateau type and the ridge type.Clinical Relevance:The variations in the lateral intercondylar ridge may affect measurement accuracy during evaluation of ACL tunnel position while using the ridge as a landmark. The plateau-type ridge and the area of denser bone on the lateral intercondylar wall may provide a new way for surgeons to determine the femoral tunnel.

Use of Blumensaat's line for assessment of cranial tibial subluxation in dogs with cranial cruciate ligament deficiency.

This study aimed to determine whether Blumensaat's line, a consistently present radiographic feature delineating the peak of the femoral intercondylar fossa, could be used to assess for cranial tibial subluxation in canine stifles with cranial cruciate ligament disease. Thirty sequential, neutrally positioned, standing-angle stifle radiographs were taken from dogs presenting to a specialist referral centre for treatment of cruciate ligament disease. Thirty similarly positioned radiographs of healthy canine stifles were used as a control group. The radiographs were anonymised and submitted to blinded observers for measurement of the tibial plateau angle, patella tendon angle, Blumensaat's line length and the length of Blumensaat's line cranial to the tibial mechanical axis. Finding that the tibial mechanical axis intersects Blumensaat's line cranial to its midpoint, as a marker of cranial tibial subluxation, had a positive predictive value of 76% for subsequent surgical identification of cruciate ligament disease. Tibial cranial subluxation is detectable and quantifiable radiographically using the intersection of the tibial mechanical axis and Blumensaat's line. Once quantified, this measurement could be used both as a radiographic marker of cruciate ligament disease and to adjust tibial osteotomy procedures to minimise the risk of under advancement of the tibial tuberosity resulting in a persistently unstable stifle.

Posteriorly positioned femoral grafts decrease long-term failure in anterior cruciate ligament reconstruction, femoral and tibial graft positions did not affect long-term reported outcome

PurposeTo investigate the effect that femoral and tibial tunnel positions have on long-term reported and clinical outcome and to identify a safe zone based on favourable outcome.MethodsSeventy-eight patients from a previous randomised controlled trial were included and were followed with a mean follow-up of 11.4 years. All patients had primary trans-tibial anterior cruciate ligament reconstruction performed. The femoral and tibial tunnel positions were visualised and translated in percentages with three-dimensional computed tomography post-operatively. There were 3 separate outcome variables: patient-reported outcome measured with the IKDC Subjective Knee Form, overall failure, and radiographic osteoarthritis. The correlation between tunnel aperture positions and outcome was determined with multivariate regression. The area with best outcome was defined as the safe zone and was determined with Youden’s index in conjunction with receiver operating characteristics.ResultsNo significant relationship was found between tunnel aperture positions and IKDC Subjective Knee Form at 10-year follow-up. The posterior-to-anterior femoral tunnel aperture position parallel to Blumensaat line showed a significant relationship (p = 0.03) to overall failure at 10-year follow-up. The mean posterior-to-anterior tunnel position of the group that did not fail was 37.7% compared to 44.1% in the overall failure group. Femoral tunnel apertures placed further anteriorly had more overall failures at long-term. The cut-off point lies at 35.0% from posterior-to-anterior parallel to Blumensaat. Of the 16 overall failures, 15 (93.8%) were placed further anteriorly than the cut-off point. No significant relationship was found between tunnel aperture positions and radiographic osteoarthritis.ConclusionFemoral and tibial tunnel positions were not associated with long-term patient-reported outcome and radiographic osteoarthritis. Long-term overall failure was more frequently seen in patients with a more anteriorly placed femoral tunnel. This study identified a safe zone located at the most posterior 35% of the femoral condyle parallel to Blumensaat. This knowledge offers guidance to surgeons to operate more precisely and accurately and reconstruct a long-lasting graft.Level of evidenceLevel III.

Comparison of Weightbearing and Nonweightbearing Juvenile Osteochondritis Dissecans Lesions of the Lateral Femoral Condyle.

Background:Repetitive microtrauma may contribute to osteochondritis dissecans (OCD) lesions of the femoral condyle. The effect of differential loading between OCD weightbearing (WB) zones has not been studied.Purpose:To determine whether clinical and radiographic variables differ by WB zone in lateral femoral condyle OCD lesions.Study Design:Cohort study; Level of evidence, 3.Methods:We retrospectively reviewed a consecutive series of patients aged <18 years with lateral femoral condyle OCD lesions presenting at a single institution between 2004 and 2018. Patients with OCD lesions outside of the lateral femoral condyle were excluded. Lesions were localized on radiographs using the Cahill and Berg classification, referencing the Blumensaat line and an extension of the posterior femoral cortex. Progeny bone characteristics evaluated at baseline and 24-month follow-up included ossification, distinct borders from parent bone, and displacement. Baseline lesion dimensions were measured on magnetic resonance imaging (MRI) scans. We evaluated posttreatment pain level, return-to-activity rate, and patient-reported outcome measures (PROMs) including the Pediatric International Knee Documentation Committee score, Knee injury and Osteoarthritis Outcome Score, and Pediatric Functional Activity Brief Scale.Results:A total of 62 lateral femoral condyle OCD lesions (mean follow-up, 24.1 months) presented within the study period: 26 WB lesions and 36 nonweightbearing (NWB) lesions. At presentation, no differences between the lesion types were observed in symptom chronicity or symptomatology. NWB lesions were deeper on MRI scans (sagittal depth, 7.11 vs 5.96 mm; P = .046; coronal depth ratio, 0.05 vs 0.01 mm; P = .003), were more likely to develop progeny bone (69.4% vs 44%; P = .047), and demonstrated higher radiographic healing rates (52.8% vs 24%; P = .025) compared with WB lesions. PROMs at follow-up were available for 25 of 62 patients (40.3%), with no statistically significant differences between cohorts at any time. Return to full activity was observed in 72% of WB and 82.1% of NWB lesions (P = .378).Conclusion:Lateral femoral condyle OCD lesions of the knee in WB and NWB zones presented similarly at initial evaluation; however, NWB lesions demonstrated higher rates of progeny bone formation and radiographic healing at mean 2-year follow-up.

Radiological Evaluation of Age- and Gender-Related Changes in the Blumensaat Line

Radiological Evaluation of Age- and Gender-Related Changes in the Blumensaat Line

Influence of femoral tunnel exit on the 3D graft bending angle in anterior cruciate ligament reconstruction

PurposeTo quantify the influence of the femoral tunnel exit (FTE) on the graft bending angle (GBA) and GBA-excursion throughout a full range of motion (ROM) in single-bundle anterior cruciate ligament (ACL) reconstruction.MethodsThree-dimensional (3D) surface models of five healthy knees were generated from a weight-bearing CT obtained throughout a full ROM (0, 30, 60, 90, 120°) and femoral and tibial ACL insertions were computed. The FTE was simulated for 16 predefined positions, referenced to the Blumensaat's line, for each patient throughout a full ROM (0, 30, 60, 90, 120°) resulting in a total of 400 simulations. 3D GBA was calculated between the 3D directional vector of the ACL and the femoral tunnel, while the intra-articular ACL insertions remained unchanged. For each simulation the 3D GBA, GBA-excursion, tunnel length and posterior tunnel blow-out were analysed.ResultsOverall, mean GBA decreased with increasing knee flexion for each FTE (p < 0.001). A more distal location of the FTE along the Blumensaat's line resulted in an increase of GBA and GBA-excursion of 8.5 ± 0.6° and 17.6 ± 1.1° /cm respectively (p < 0.001), while a more anterior location resulted in a change of GBA and GBA-excursion of -2.3 ± 0.6° /cm (+ 0.6 ± 0.4°/ cm from 0–60° flexion) and 9.8 ± 1.1 /cm respectively (p < 0.001).Mean tunnel length was 38.5 ± 5.2 mm (range 29.6–50.5). Posterior tunnel blow-out did not occur for any FTE.ConclusionAiming for a more proximal and posterior FTE, with respect to Blumensaat’s line, reliably reduces GBA and GBA-excursion, while preserving adequate tunnel length. This might aid to reduce excessive graft stress at the femoral tunnel aperture, decrease femoral tunnel widening and promote graft-healing.Level of EvidenceIV