Lower anatomical femoral ACL tunnel can be created in the large volume of femoral intercondylar notch.

PURPOSE: The purpose of this study was to investigate the correlation between femoral intercondylar notch volume and the characteristics of femoral tunnels in anatomical single bundle anterior cruciate ligament (ACL) reconstruction. METHODS: Fifty-one subjects (24 male and 27 female: median age 27: range 15-49), were included in this study. Anatomical single bundle ACL reconstruction was performed in all subjects using a trans-portal technique. Femoral tunnel length was measured intra-operatively. Three-dimensional computed tomography (3D-CT) was taken at pre and post-surgery. The intercondylar notch volume was calculated with a truncated-pyramid shape simulation using the pre-operative 3D-CT image. In the post-operative 3D-CT, the modified quadrant method was used to measure femoral ACL tunnel placement. RESULTS: Femoral tunnel placement was 47.6 ± 10.5% in the high-low (proximal-distal) direction, and 22.6 ± 5.4% in the shallow-deep (anterior-posterior) direction. Femoral tunnel length was 35.3 ± 4.4 cm. Femoral intercondylar notch volume was 8.6 ± 2.1cm3. A significant correlation was found between femoral intercondylar notch volume and high-low (proximal-distal) femoral tunnel placement (Pearson's coefficient correlation: 0.469, p = 0.003). CONCLUSION: Femoral ACL tunnel placement at a significantly lower level was found in knees with large femoral intercondylar notch volume in the trans-portal technique. For the clinical relevance, although the sample size of this study was limited, surgeons can create femoral ACL tunnel low (distal) in the notch where close to the anatomical ACL footprint in the knees with large femoral intercondylar notch volume. LEVEL OF EVIDENCE: III.

The radiographic tibial spine area is correlated with the occurrence of ACL injury.

PURPOSE: The purpose of this study was to reveal the possible influence of the tibial spine area on the occurrence of ACL injury. METHODS: Thirty-nine subjects undergoing anatomical ACL reconstruction (30 female, 9 male: average age 29 ± 15.2) and 37 subjects with intact ACL (21 female, 16 male: average age 29 ± 12.5) were included in this study. In the anterior-posterior (A-P) and lateral knee radiograph, the tibial spine area was measured using a PACS system. In axial knee MRI exhibiting the longest femoral epicondylar length, the intercondylar notch area was measured. Tibial spine area, tibial spine area/body height, and tibial spine area/notch area were compared between the ACL tear and intact groups. RESULTS: The A-P tibial spine area of the ACL tear and intact groups was 178 ± 34 and 220.7 ± 58mm2, respectively. The lateral tibial spine area of the ACL tear and intact groups was 145.7 ± 36.9 and 178.9 ± 41.7mm2, respectively. The tibial spine area was significantly larger in the ACL intact group when compared with the ACL tear group (A-P: p = 0.02, lateral: p = 0.03). This trend was unchanged even when the tibial spine area was normalized by body height (A-P: p = 0.01, lateral: p = 0.02). The tibial spine area/notch area of the ACL tear and intact groups showed no significant difference. CONCLUSION: The A-P and lateral tibial spine area was significantly smaller in the ACL tear group when compared with the ACL intact group. Although the sample size was limited, a small tibial spine might be a cause of knee instability, which may result in ACL injury. LEVEL OF EVIDENCE: Level III.

Knees with straight Blumensaat's line have small volume of femoral intercondylar notch.

PURPOSE: Smaller femoral intercondylar notch volume has been identified as a risk factor for anterior cruciate ligament injury. The present study aims to investigate differences in the intercondylar notch volume based on differences in the morphology of Blumensaat's line. METHODS: Eighty-eight (88) subjects (42 male and 46 female: median age 27: range 15-49), were included in this study. Using 3-dimensional computed tomography (3D-CT), the volume of the intercondylar notch was calculated using a truncated-pyramid shape simulation with the formula: [Formula: see text]. Femoral condyle height (h) was measured in the sagittal plane of the knee in 3D-CT. The area of the intercondylar notch was measured in the axial slice containing the most proximal level (S1) and most distal level (S2) of Blumensaat's line. In the sagittal view of the knee, Blumensaat's line morphology was classified into either straight or hill type. Statistical analysis was performed to compare h, S1, S2, and notch volume between the straight and hill type groups. RESULTS: Thirty-six subjects were classified as having straight type morphology and 52 subjects were classified as having hill type morphology. The measured h, S1, and S2, of the straight and hill types were 29 ± 4 and 31 ± 4 mm, 213 ± 72 and 205 ± 51 mm2, 375 ± 114 and 430 ± 94 mm2, respectively. The calculated femoral intercondylar notch volume of the straight and hill types was 8.1 ± 2 and 9.5 ± 2 cm3, respectively. Straight type knees showed significantly smaller S2 (p = 0.04), and notch volume (p = 0.01) when compared with hill type knees. CONCLUSION: Intercondylar notch volume was significantly smaller in knees with straight type Blumensaat's line morphology. Considering that Blumensaat's line represents the roof of the femoral notch, morphological variations in Blumensaat's line are likely to reflect variation in notch volume. For clinical relevance, as a smaller notch volume is a risk factor for ACL injury, straight type Blumensaat's line may also be considered a potential risk factor for ACL injury. LEVEL OF EVIDENCE: Level III.

Truncated-pyramid shape simulation for the measurement of femoral intercondylar notch volume can detect the volume difference between ACL-injured and intact subjects.

PURPOSE: The purpose of this study was to measure the femoral intercondylar notch volume using a truncated-pyramid shape simulation and compare this volume between anterior cruciate ligament (ACL) injured and intact subjects. METHODS: Forty-seven subjects diagnosed with ACL tear by MRI (22 male and 25 female: median age 26: range 15-49), and 41 subjects in which knee MRI was performed and no ACL injury detected (20 males and 21 females: median age 27: range 16-49), were included in this study. Using three-dimensional computed tomography (3D-CT), the axial femoral intercondylar notch area was measured in the slice containing the most proximal (S1) and most distal (S2) level of Blumensaat's line. Femoral condyle height (h) was measured using a sagittal view of knees in 3D-CT. The truncated-pyramid shape simulation was calculated as: Volume = [Formula: see text]. Statistical analysis was performed to compare S1, S2, notch height, and notch volume between the ACL-injured and intact groups. RESULTS: The measured S1, S2, and the notch height of the ACL-injured and intact groups were 201 ± 64 and 214 ± 50mm2, 370 ± 91 and 461 ± 94mm2, and 31 ± 3 and 30 ± 4mm, respectively. The calculated femoral intercondylar notch volume of the ACL-injured and intact groups was 8.6 ± 2.2 and 9.9 ± 2.6cm3, respectively. The ACL intact group showed significantly larger S2 and notch volume when compared with the ACL-injured group. CONCLUSION: For clinical relevance, notch volume and most distal axial notch area parameters were significantly larger in ACL intact subjects. The truncated-pyramid shape simulation is an easy and cost-effective method to evaluate intercondylar notch volume. In knees with small femoral intercondylar notch volume, attention is needed to prevent ACL injury. LEVEL OF EVIDENCE: Level III.

The evaluation of the distance between the popliteus tendon and the lateral collateral ligament footprint and the implant in Total knee Arthroplasty using a 3-dimensional template.

BACKGROUND: The popliteus tendon (PT) or lateral collateral ligament (LCL) stabilizes the postero-lateral aspects of the knees. When surgeons perform total knee arthroplasty (TKA), PT and LCL iatrogenic injuries are a risk because the femoral attachments are relatively close to the femoral bone resection area. The purpose of this study was to evaluate the distance between the PT or LCL footprint and the TKA implant using a 3D template system and to evaluate any significant differences according to the implant model. METHODS: Eighteen non-paired formalin fixed cadaveric lower limbs were used (average age: 80.3). Whole length lower limbs were resected from the pelvis. All the surrounding soft tissue except the PT, knee ligaments and meniscus were removed from the limb. Careful dissection of the PT and LCL was performed, and the femoral footprints were detected. Each footprint periphery was marked with a 1.5 mm K-wire. Computed tomography (CT) scanning of the whole lower limb was then performed. The CT data was analyzed with a 3D template system. This simulation models for TKA were the Journey II BCS and the Persona PS. The area of each footprint, and the length between the most distal and posterior point of the lateral femoral condyle and the edge of each footprint were measured. Matching the implant model to the CT image of the femur, the shortest length between each footprint and the bone resection area were calculated. RESULTS: PT and LCL footprint were detected in all knees. The area of the PT and LCL footprints was 38.7 ± 17.7 mm2 and 58.0 ± 24.6 mm2, respectively. The length between the most distal and posterior point of the lateral femoral condyle and the edge of the PT footprint was 10.3 ± 2.4 mm and 14.2 ± 2.8 mm, respectively. The length between most distal and most posterior point of the lateral femoral condyle and the edge of the LCL footprint was 16.3 ± 2.3 mm and 15.5 ± 3.3 mm, respectively. Under TKA simulation, the shortest length between the PT footprint and the femoral bone resection area for the Journey II BCS and the Persona PS was 4.3 ± 2.5 mm and 3.2 ± 2.9 mm, respectively. The shortest length between the LCL footprint and the femoral bone resection area for the Journey II BCS and the Persona PS was 7.2 ± 2.3 mm and 5.6 ± 2.1 mm, respectively. The PT attachment was damaged by the bone resection of the Journey II BCS and the Persona PS TKA in 3 and 9 knees, respectively. CONCLUSION: The PT and LCL femoral attachments existed close to the femoral bone resection area of the TKA. To prevent postero-lateral instability in TKA, careful attention is needed to avoid damage to the PT and LCL during surgical procedures.

The occurrence of ACL injury influenced by the variance in width between the tibial spine and the femoral intercondylar notch.

PURPOSE: The purpose of this study was to reveal the influence of the variance in width between the tibial spine and the femoral intercondylar notch on the occurrence of ACL injury. METHODS: Thirty-nine subjects undergoing anatomical ACL reconstruction (30 female, 9 male; average age 29 ± 15.2) and 37 subjects with intact ACL (21 female, 16 male; average age 29 ± 12.5) were included in this study. In the anterior-posterior knee radiograph, tibial spine height, and the length between the top of the medial and lateral tibial spine (tibial spine width) were measured. In axial knee MRI exhibiting the longest femoral epicondylar length, intercondylar notch outlet length was measured and notch width index was calculated. Tibial spine width/notch outlet length, and tibial spine width/notch width index were compared between the ACL tear and intact groups. RESULTS: Tibial spine width/notch outlet length of the ACL tear and intact groups was 0.6 ± 0.1 and 0.7 ± 0.1, respectively. Tibial spine width/notch width index of the ACL tear and intact groups was 0.4 ± 0.1, and 0.6 ± 0.1, respectively. Both parameters were significantly larger in the ACL intact group. CONCLUSION: Both tibial spine width/notch outlet length and tibial spine width/notch width index were significantly smaller in the ACL tear group when compared with the ACL intact group. The occurrence of ACL injury influenced by the variance in width between the tibial spine and the femoral intercondylar notch. LEVEL OF EVIDENCE: III.

Morphology of the resident's ridge, and the cortical thickness in the lateral wall of the femoral intercondylar notch correlate with the morphological variations of the Blumensaat's line.

PURPOSE: The purpose of this study was to reveal the morphological correlation between the lateral wall of femoral intercondylar notch and the Blumensaat's line. METHODS: Forty-one non-paired human cadaveric knees were included in this study (23 female, 18 male: median age 83). Knees were resected, and 3 dimensional computed tomography (3D-CT) was performed. In the axial CT image, bony protrusion (resident's ridge) and cortical thickness in the lateral wall of the femoral intercondylar notch were detected. The length between the top of the ridge, or the most anterior, middle, and most posterior border of cortical thickness and posterior femoral condylar line was measured. Following Iriuchishima's classification, the morphology of the Blumensaat's line was classified into straight and hill types (small and large hill types). In the hill types, the length between the hilltop and the posterior border of the Blumensaat's line or the posterior border of the femoral condyle was evaluated. Statistical correlation was calculated between the top of the ridge location, cortical thickness location in the notch, and hilltop location. RESULTS: There were 7 straight type knees and 34 hill type knees (9 small hill type knees and 25 large hill type knees). Only the hill types of knees were evaluated. The top of the ridge, anterior margin, middle, and posterior border of cortical thickness in the lateral wall of the femoral intercondylar notch existed at 61.8 ± 4.6%, 58.3 ± 12.3%, 42.1 ± 7.9%, and 25.5 ± 5.4% from the posterior condylar line, respectively. The hilltop existed at 24.9 ± 5.9% and 30.7 ± 5.0%, from the posterior border of the Blumensaat's line and from the posterior border of the femoral condyle, respectively. Significant correlation was observed between resident's ridge top, cortical thickness location and hilltop location. CONCLUSION: In all cadaveric knees, cortical thickness was detected in the lateral wall of the femoral intercondylar notch. The resident's ridge and cortical thickness location had significant correlation with the hill location in the Blumensaat's line, indicating a continuation of the cortical bone from the posterior cortex of the femoral shaft via the hilltop of the Blumensaat's line to the cortical thickness in the lateral wall of the femoral intercondylar notch. For clinical relevance, hilltop location in the Blumensaat's line is a new bony landmark in anterior cruciate ligament surgery.

The location of the femoral ACL footprint center is different depending on the Blumensaat's line morphology.

PURPOSE: The purpose of this study was to evaluate the difference in the center point of the femoral ACL footprint according to the morphological variations of the Blumensaat's line. METHODS: Fifty-nine non-paired human cadaver knees were used. The ACL was cut in the middle, and the femoral bone was cut at the most proximal point of the femoral notch. Digital images were evaluated using the Image J software. The periphery of the femoral ACL footprint was outlined and the center point was measured automatically. Following Iriuchishima's classification, the morphology of the Blumensaat's line was classified into straight and hill types (small and large hill types). The center of the femoral ACL footprint and hilltop placement were evaluated using the quadrant method. A quadrant grid was placed uniformly, irregardless of hill existence, and not including the articular cartilage. A correlation analysis was performed between the center point of the femoral ACL footprint and hilltop placement. RESULTS: The straight type consisted of 19 knees, and the hill type 40 knees (small hill type 13 knees and large hill type 27 knees). The center of the femoral ACL footprint (shallow-deep/high-low) in the straight and hill type knees was 33.7/47.6%, and 37.2/50.3%, respectively. In the hill type, the ACL footprint center was significantly more shallow when compared to the straight type. Significant correlation was observed between the center point of the femoral ACL footprint and hilltop placement of the Blumensaat's line. CONCLUSION: The center point of the femoral ACL footprint was significantly more shallow in the hill type knees when compared to the straight type. For clinical relevance, considering that the location of the femoral ACL footprint center is different depending on the Blumensaat's line morphology, to perform accurate ACL reconstruction, femoral ACL tunnel placement should be made based on Blumensaat's line morphological variations.

Correlation between the mid-substance cross-sectional anterior cruciate ligament size and the knee osseous morphology.

INTRODUCTION: One of the final goals of anatomical anterior cruciate ligament (ACL) reconstruction is the restoration of native anatomy. It is essential to obtain more accurate predictors of mid-substance ACL size before surgery. However, to the best of our knowledge, no study has reported correlation between the mid-substance cross-sectional ACL size and the knee osseous morphology. The purpose of this study was to reveal correlation between the mid-substance cross-sectional ACL size and the knee osseous morphology. MATERIALS AND METHODS: We used 39 non-paired formalin fixed Japanese cadaveric knees. All surrounding muscles, ligaments and soft tissues in the knee were resected. After soft tissue resection, the knee was flexed at 90°, and a tangential plane of the femoral posterior condyles was marked and cut the ACL. Femoral ACL footprint size, Blumensaat's line length, lateral wall of the femoral intercondylar notch size, lateral wall of the femoral intercondylar notch height, tibial ACL footprint size, tibia plateau size, the whole anterior-posterior (AP) length, the medial and the lateral AP length of the tibia plateau, and the medial-lateral (ML) length of the tibia plateau were measured. The Pearson's product movement correlation was calculated to reveal correlation between the mid-substance cross-sectional ACL size and the measured parameters of the knee osseous morphology. RESULTS: The measured mid-substance cross-sectional ACL size was 49.9 ± 16.3 mm2. The tibial ACL footprint size, the tibia plateau size, the whole AP length of the tibia plateau, the lateral AP length of the tibia plateau and the ML length of the tibia plateau were significantly correlated with the mid-substance cross-sectional ACL size. CONCLUSIONS: For clinical relevance, some tibial sides of the knee osseous morphology were significantly correlated with the mid-substance cross-sectional ACL size. It might be possible to predict the mid-substance ACL size measuring these parameters.

Evaluation of age-related differences in anterior cruciate ligament size.

PURPOSE: The purpose of this study was to reveal the relation between age and the morphological characteristics of the anterior cruciate ligament (ACL) using magnetic resonance imaging (MRI). METHODS: Thirty-seven young subjects who were diagnosed with a meniscus injury without ACL tear using MRI (15 male and 22 female, median age 26, range 15-49), and 33 elderly subjects for whom knee MRI was performed before uni-compartmental knee arthroplasty (11 male and 22 female, median age 77, range 60-83), were included in this study. In the elderly group, healthy ACL gross morphology was confirmed macroscopically during surgery. In all knees, ACL was detected without any intensity alteration. In the MRI evaluation, using the axial slice revealing the greatest length between the medial and lateral epicondyle of the femur, axial ACL size was evaluated. Using the coronal plane image, the sagittal image was sliced parallel with the native ACL. In the sagittal image of the MRI, the largest area of the ACL was measured. Statistical analysis was performed to reveal the correlation between age and ACL size. Both axial and sagittal ACL areas were compared between the young and elderly groups. RESULTS: Age and sagittal ACL area were significantly correlated (Pearson's coefficient correlation: - 0.353, P = 0.003). The sagittal ACL area was significantly larger in the young group when compared with the elderly group (P = 0.001). However, when the sagittal ACL area was normalized by the length of Blumensaat's line, no significant difference was observed. CONCLUSION: For clinical relevance, sagittal ACL size was significantly larger in young subjects. The reason for this difference is likely the difference in knee size. When performing anatomical studies of the ACL using cadaveric knees of elderly specimens, there is the possibility that the ACL size will be underestimated. Considering that the ACL surgery is mainly performed for young subjects, cadavers of younger age should be used in such studies. LEVEL OF EVIDENCE: Diagnostic study, Level III.

Femoral tunnel length in anatomical single-bundle ACL reconstruction is correlated with height, weight, and knee bony morphology.

PURPOSE: The purpose of this study was to reveal the correlation between femoral tunnel length in anatomical single-bundle anterior cruciate ligament (ACL) reconstruction and body size and/or knee morphology. METHODS: Thirty-one subjects undergoing anatomical single-bundle ACL reconstruction were included in this study (20 female, 11 male; median age 46, 15-63). Pre-operative height, body weight, and body mass index (BMI) were measured. In pre-operative magnetic resonance imaging, the thickness of the quadriceps tendon and the whole anterior-posterior (AP) length of the knee were measured using the sagittal slice. Using post-operative three-dimensional computed tomography, accurate axial and lateral views of the femoral condyle were evaluated. The correlation of femoral tunnel length, which was measured intra-operatively, with the height, weight, BMI, quadriceps tendon thickness, AP length of the knee, trans-epicondylar length, the notch area (axial), length of Blumensaat's line, and the height and area of the lateral wall of the femoral intercondylar notch were statistically analyzed. Tunnel placement was also evaluated using a Quadrant method. RESULTS: The average femoral tunnel length was 35.6 ± 4.4 mm. The average height, body weight, and BMI were 162.7 ± 7.2 cm, 61.9 ± 10 kg, and 23.4 ± 3.5, respectively. Femoral tunnel length was significantly correlated with height, body weight and the height and area of lateral wall of the femoral intercondylar notch, and the length of the Blumensaat's line. CONCLUSION: For clinical relevance, the risk of creating a femoral tunnel of insufficient length in anatomical single-bundle ACL reconstruction exists in subjects with small body size. Surgeons should pay careful attention to prevent this from occurring. LEVEL OF EVIDENCE: Case-controlled study, Level III.

The Blumensaat's line morphology influences to the femoral tunnel position in anatomical ACL reconstruction.

PURPOSE: The purpose of this study was to reveal the influence of the morphological variations of the Blumensaat's line on femoral tunnel position in anatomical anterior cruciate ligament (ACL) reconstruction. METHODS: Thirty-eight subjects undergoing anatomical single-bundle ACL reconstruction were included in this study (22 female, 16 male: median age 45: 15-63). Using a trans-portal technique, the femoral tunnel was targeted to reproduce the center of antero-medial bundle. Following Iriuchishima's classification, the morphology of the Blumensaat's line was classified into straight and hill types (small and large hill types). Femoral ACL tunnel position was evaluated using the quadrant method. When the quadrant method grid was applied, the baseline of the grid was matched to the anterior part of the Blumensaat's line, without considering the existence of a hill. Using pre-operative 3D-CT data, the axial and sagittal morphology of the knee was also compared, establlishing straight and hill types. RESULTS: There were 12 straight type knees and 26 hill type knees (7 small hill type knees and 19 large hill type knees). The femoral tunnel position in straight type knees was 23.6 ± 3.7% in the shallow-deep direction, and 41.3 ± 8.2% in the high-low direction. In hill type knees, the tunnel position was 27 ± 4.7% in the shallow-deep direction, and 51 ± 10.1% in the high-low direction. The femoral tunnel was placed significantly more shallow and lower in hill type knees when compared with straight type knees. CONCLUSION: Femoral ACL tunnel placement was significantly influenced by the morphological variations of the Blumensaat's line. As detecting morphological variation in arthroscopic surgery is difficult, surgeons should confirm such variations pre-operatively using radiograph or CT so as to avoid making extremely shallow and low tunnels in hill type knees. LEVEL OF EVIDENCE: Case-controlled study, III.

The correlation between the femoral anterior cruciate ligament footprint area and the morphology of the distal femur: three-dimensional CT evaluation in cadaveric knees.

BACKGROUNDS: "Anatomical" anterior cruciate ligament (ACL) reconstruction is defined as the functional restoration of the ACL to its native dimensions. It is essential to obtain more accurate predictors of ACL size before surgery. The purpose of this study was to investigate the correlation between the native femoral ACL footprint size and the morphology of the distal femur using three-dimensional CT (3D-CT). METHODS: Thirty non-paired Japanese human cadaver knees were used. All soft tissues around the knee were resected except the ACL. For the evaluation of femoral condyle morphology, trans-epicondylar length (TEL), notch outlet length, axial notch area, and notch width index were measured using 3D-CT. The ACL was cut in the middle, and the femoral bone was cut at the most proximal point of the femoral notch. The ACL was carefully dissected, and the boundaries of the ACL insertion site were outlined on the femoral side. An accurate lateral view of the femoral condyle was photographed with a digital camera. The size of the femoral ACL footprint, length of Blumensaat's line, and the height and area of the lateral wall of the femoral intercondylar notch were measured with ImageJ software. RESULTS: Notch height, lateral notch area, and TEL were significantly correlated with the femoral ACL footprint area. Both axial notch area and notch outlet length were significantly correlated with the femoral mid-substance insertion area. CONCLUSION: Morphological evaluation using 3D-CT preoperatively may be useful in predicting the femoral ACL footprint size.

Sagittal femoral condyle morphology correlates with femoral tunnel length in anatomical single bundle ACL reconstruction.

PURPOSE: The purpose of this study was to reveal the correlation between femoral tunnel length and the morphology of the femoral intercondylar notch in anatomical single bundle anterior cruciate ligament (ACL) reconstruction using three-dimensional computed tomography (3D-CT). METHODS: Thirty subjects undergoing anatomical single bundle ACL reconstruction were included in this study (23 female, 7 male: average age 45.5 ± 16.7). In the anatomical single bundle ACL reconstruction, the femoral and tibial tunnels were created close to the antero-medial bundle insertion site with trans-portal technique. Using post-operative three-dimensional computed tomography (3D-CT), accurate axial and lateral views of the femoral condyle were evaluated. The correlation of femoral tunnel length, which was measured intra-operatively, with the transepicondylar length (TEL), notch width index, notch outlet length, the notch area (axial), length of Blumensaat's line, and the height and area of the lateral wall of the femoral intercondylar notch was statistically analyzed. Tunnel placement was also evaluated using a Quadrant method. RESULTS: The average femoral tunnel length was 35.4 ± 4.4 mm. The average TEL, NWI, notch outlet length, and the axial notch area, were 76.9 ± 5.1 mm, 29.1 ± 3.8%, 19.5 ± 3.9 mm, and 257.4 ± 77.4 mm2, respectively. The length of Blumensaat's line and the height and area of the lateral wall of the femoral intercondylar notch were 33.8 ± 3.2 mm, 22.8 ± 2.3 mm, and 738.7 ± 129 mm2, respectively. The length of Blumensaat's line, the height, and the area of the lateral wall of the femoral intercondylar notch were significantly correlated with femoral tunnel length. Femoral tunnel placement was 23.4 ± 4.5% in a shallow-deep direction and 35.4 ± 8.8% in a high-low direction. CONCLUSION: The length of Blumensaat's line, height, and area of the lateral wall of the femoral intercondylar notch are correlated with femoral tunnel length in anatomical single bundle ACL reconstruction. For clinical relevance, these parameters are useful in predicting the length of the femoral tunnel in anatomical single bundle ACL reconstruction for the prevention of extremely short femoral tunnel creation. LEVEL OF EVIDENCE: Case controlled study, Level III.

The importance of Blumensaat's line morphology for accurate femoral ACL footprint evaluation using the quadrant method.

PURPOSE: The purpose of this study was to evaluate the difference in the center position of the ACL footprint based on grid placement using the quadrant method according to the morphological variations of the Blumensaat's line. METHODS: Fifty-nine non-paired human cadaver knees were used. The ACL was cut in the middle, and the femoral bone was cut at the most proximal point of the femoral notch, and the digital images were evaluated using Image J software. The femoral ACL footprint was periphery outlined and the center position was automatically measured. Following Iriuchishima's classification, the morphology of the Blumensaat's line was classified into straight, small hill, and large hill types. From the images, grid quadrants were placed as: Grid (1) without consideration of hill existence and not including the chondral lesion. Grid (2) without consideration of hill existence and including the chondral lesion. Grid (3) with consideration of hill existence and not including the chondral lesion. Grid (4) with consideration of hill existence and including the chondral lesion. RESULTS: The straight type consisted of 19 knees, the small hill type 13 knees, and the large hill type 27 knees. Depending on the quadrant grid placement, significant center position difference was observed both in the shallow-deep, and high-low direction. When hill existence was considered, the center position of the ACL was significantly changed to a high position. CONCLUSION: The center position of the ACL footprint exhibited significant differences according to Blumensaat's line morphology. For clinical relevance, when ACL surgery is performed in knees with small or large hill type variations, surgeons should pay close attention to femoral tunnel evaluation and placement, especially when using the quadrant method.

Compensatory mechanism of the spine after corrective surgery without lumbar-sacral fixation for traumatic thoracolumbar kyphotic spine deformity.

BACKGROUND: It remains unclear whether long fusion including lumbar-sacral fixation is needed in corrective surgery to obtain good global sagittal balance (GSB) for the treatment of traumatic thoracolumbar kyphotic spine deformity. The purposes of this study were to evaluate compensatory mechanism of the spine after corrective surgery without lumbar-sacral fixation and to evaluate the parameters affecting the achievement of good GSB post-operatively. METHODS: Twenty (20) subjects requiring corrective surgery (distal end of fixation was L3) were included in this study. The radiographic parameters were measured pre-operatively and at one month after surgery. Sagittal Vertical Axis (SVA), Lumber Lordosis angle altered by fracture (fLL), Thoracic Kyphosis angle altered by fracture (fTK), Pelvic Tilt (PT), Sacral Slope (SS), Pelvic Incidence (PI), Segmental Lumbar Lordosis (sLL: L3-S/L4-S), and local kyphotic angle were measured. The correlation between correction of local kyphotic angle (CLA) and the change in radiographic parameters was evaluated. Post-operatively, subjects with SVA<50 mm and PI-fLL<10°were regarded as the "good GSB group (G group). The radiographic parameters affecting the achievement of G group were statistically evaluated. RESULTS: fLL, sLL:L3-S and sLL:L4-S were decreased indirectly because the local kyphosis was corrected directly (CLA: 26.5 ± 8.6°) (P < 0.001). CLA and the change in fLL showed significant correlation (r = 0.821), the regression equation being: Y = -0.63X+3.31 (Y: The change in fLL, X: CLA). The radiographic parameters significantly affecting the achievement of G group were: SVA, PT, PI-fLL, sLL: L3-S, and sLL: L4-S (P < 0.01). CONCLUSION: The main compensatory mechanism was the decrease of lordosis in the lumbar spine. fLL was decreased to approximately 60% of CLA after surgery. SVA was not corrected by the compensatory mechanism.

The correlation between femoral sulcus morphology and osteoarthritic changes in the patello-femoral joint.

PURPOSE: The purpose of this study was to reveal the correlation between the type of lesion and the depth of osteoarthritic (OA) changes in the patello-femoral (PF) joint and its bony morphological characteristics using computed tomography (CT) data. METHODS: Eighty-seven cadaveric knees were included in this study with median age of 83 years (62-97). OA depth evaluation was performed following Outerbridge's classification. Patella OA lesions were classified macroscopically using Han's method: type (1) no or minimal lesion, type (2) medial facet lesion without involvement of the ridge, type (3) lateral facet lesion without involvement of the ridge, type (4) lesion involving the ridge only, type (5) medial facet lesion with involvement of the ridge, type (6) lateral facet lesion with involvement of the ridge, and type (7) global lesion. Femoral-side OA lesions in the PF joint were classified using a modified Chang's method. Type (1) no or minimal lesion, type (2) medial facet lesion, type (3) centre of patella groove lesion, type (4) lateral facet lesion, and type (5) global lesion. Whole-body CTs of all cadavers were taken before knee dissection. Using the CT data, patella morphology was evaluated following Wiberg's classification. Femoral sulcus angle (SA), sulcus depth (SD), and sulcus width (SW) were also measured using CT data. RESULTS: The measured SA, SD, and SW were 144.8° ± 7.2°, 7.0 ± 1.6 mm and 3.4 ± 0.3 mm, respectively. When patella OA depth was divided into grades 1-2 (n = 30) and grades 3-4 (n = 57), the SD of grade 1-2 knees was 6.5 ± 1.3 mm, and the SD of grade 3-4 knees was 7.3 ± 1.6 mm, constituting a significant difference (p = 0.01). No significant difference in either SA or SW was observed between the two groups. Patella OA lesion, femoral-side OA lesion, and depth were not affected by SA, SD, or SW. Wiberg's classification also showed no significant correlation with PF-OA. CONCLUSION: Deep SD was significantly correlated with the incidence of severe patella OA. Wiberg's classification, SA, and SW were not correlated with PF-OA. For clinical relevance, there is a risk of PF-OA progression in patients with deep SD, and treatment should be applied accordingly.

The correlation of femoral tunnel length with the height and area of the lateral wall of the femoral intercondylar notch in anatomical single-bundle ACL reconstruction.

PURPOSE: The purpose of this study was to reveal the correlation between femoral tunnel length and the height and area of the lateral wall of the femoral intercondylar notch in anatomical single-bundle anterior cruciate ligament (ACL) reconstruction . METHODS: Twenty-four subjects undergoing anatomical single-bundle ACL reconstruction were included in this study (19 females and 5 males; average age 45.5 ± 16.7). In the anatomical single-bundle ACL reconstruction, the femoral and tibial tunnels were created close to the anteromedial bundle insertion site. Using post-operative three-dimensional computed tomography (3D-CT), an accurate lateral view of the femoral condyle was evaluated. The correlation of femoral tunnel length, which was measured intra-operatively, with the length of Blumensaat's line, and the height and area of the lateral wall of the femoral intercondylar notch was statistically analysed. Tunnel placement was also evaluated using 3D-CT (Quadrant method). RESULTS: The average femoral tunnel length was 35.3 ± 4.9 mm. The length of Blumensaat's line, and the height and area of the lateral wall of the femoral intercondylar notch were 33.6 ± 3.4, 22.8 ± 2.4, and 734.6 ± 136 mm2, respectively. Both the height and the area of the lateral wall of the femoral intercondylar notch were significantly correlated with femoral tunnel length. Femoral tunnel placement was 24.1 ± 3.9 % in a shallow-deep direction, and 33.5 ± 7.7 % in a high-low direction. CONCLUSION: The height and area of the lateral wall of the femoral intercondylar notch are correlated with femoral tunnel length in anatomical single-bundle ACL reconstruction. For clinical relevance, surgeons should be careful not to make the femoral tunnel too short in knees in which the femoral intercondylar notch is low in height or small in size. LEVEL OF EVIDENCE: Case-controlled study, Level III.

The evaluation of muscle recovery after anatomical single-bundle ACL reconstruction using a quadriceps autograft.

PURPOSE: The purpose of this study was to reveal the degree of muscle recovery and report the clinical results of anatomical single-bundle ACL reconstruction using a quadriceps autograft. METHODS: Twenty subjects undergoing anatomical single-bundle ACL reconstruction using a quadriceps autograft were included in this study. A 5-mm-wide, 8-cm-long graft, involving the entire layer of the quadriceps tendon, was harvested without bone block. The average graft diameter was 8.1 ± 1.4 mm. An initial tension of 30 N was applied. The femoral tunnel was created from the far-medial portal. Each femoral and tibial tunnel was created close to the antero-medial bundle insertion site. For the evaluation of muscle recovery (quadriceps and hamstring), a handheld dynamometer was used. The evaluation of muscle recovery was performed pre-operatively, and at 3, 6, 9, and 12 months after surgery. Muscle recovery data were calculated as a percentage of leg strength in the non-operated leg. Anterior tibial translation (ATT), pivot shift test, and IKDC score were evaluated. RESULTS: The average quadriceps strength pre-operatively, and at 3, 6, 9, and 12 months after ACL reconstruction was 90.5 ± 19, 67.8 ± 21.4, 84 ± 17.5, and 85.1 ± 12.6 %, respectively. The average hamstring strength pre-operatively, and at 3, 6, 9, and 12 months after ACL reconstruction was 99.5 ± 13.7, 78.7 ± 11.4, 90.5 ± 19, and 96.7 ± 13.8 %, respectively. ATT pre-operatively and at 12 months after surgery was 5.4 ± 1.3 and 1.0 ± 0.8 mm, respectively. No subjects exhibited positive pivot shift after surgery. Within 6 months following surgery, quadriceps hypotrophy was observed in all subjects. However, the hypotrophy had recovered at 12 months following surgery. No subjects complained of donor site pain after surgery. CONCLUSION: Anatomical single-bundle ACL reconstruction using a quadriceps autograft resulted in equivalent level of muscle recovery and knee stability when compared with previously reported ACL reconstruction using hamstrings tendon with no donor site complications. LEVEL OF EVIDENCE: Case controlled study, Level III.

Prevalence and risk factors of deep vein thrombosis in patients undergoing lumbar spine surgery.

BACKGROUND: Spinal surgery is classified as a moderate risk for DVT. The occurrence of DVT after various spinal surgical procedures was reviewed retrospectively, and the perioperative risk factors in the high-risk group were identified. In addition, the administration of the factor Xa inhibitor to DVT subjects with unstable thrombosis was evaluated to reveal its effectiveness in the prevention of PTE and postoperative complications. METHODS: This study included 588 subjects who underwent lumbar spine surgery. The patient population consisted of the following four groups: the fracture group (F group), the laminectomy group (La group), the TLIF group (T group), and the long fusion group (Lo group). Bilateral lower limb venous ultrasonography was performed on the day before surgery, the day after surgery, and one week after surgery. The incidence of DVT was determined for each group and potential risk factors were evaluated in the group with the highest incidence of DVT. Subjects with DVT who had unstable thrombosis received anticoagulant therapy (factor Xa inhibitor) and their treatment results were assessed. RESULTS: The overall incidence of DVT was 32.3% (190/588). A significantly high incidence of DVT was observed in the Lo group (54.3%; 75/138). Logistic regression and ROC analysis of potential risk factors in the Lo group identified a D-dimer value of 19.5 ug/ml at one week postoperatively as a risk factor of DVT (p = 0.02; odds ratio, 4.09; 95% CI, 2.82-7.88). Overall, 15.8% of subjects (30/190) received anticoagulant therapy. These subjects experienced neither PTE nor epidural hematoma. A follow-up ultrasonography performed at three weeks postoperatively detected the disappearance/resolution of DVT in 86.7% of these subjects (26/30). CONCLUSION: The incidence of DVT varied according to the invasiveness of the procedure. Successful management of DVT hinges on preoperative risk management involving prophylactic treatment and early diagnosis, in order to avoid PTE and other complications.