ACL footprint size is correlated with the height and area of the lateral wall of femoral intercondylar notch

Can patient anthropometry predict the anterior cruciate ligament footprint dimensions? - An MRI-based observational study on north Indian population

Background

Anterior Cruciate Ligament (ACL) reconstruction is one of the most common surgeries being currently done. As we usher into the era of Individualized Anatomic Reconstruction, it is very important to understand the native anatomy of ACL. We aimed to assess the ACL footprint dimensions in our patients and correlate it with anthropometric variables, which can help in preoperative decision making.

Method

A total of 143 eligible patients with suspected ACL injury presented during the study period. Out of which 92 were included in the study. Data on patient's age, sex, height, weight and body mass index (BMI) was recorded. The length and area of both the tibial and femoral footprints were measured on MRI. The footprint dimensions were correlated with the recorded anthropometric data.

Results

The ACL tibial footprint length and area, and femoral footprint length and area were found to be 13.3 ± 2.23 mm, 142.6 ± 26.16 mm2, 11.2 ± 1.97 mm, 125.8 ± 28.75 mm2 respectively. Footprint in males was significantly larger than females. A weak (ρ- 0.21 to 0.4) correlation with weight and moderate (ρ- 0.41 to 0.6) correlation with height was observed. Multivariate linear regression analysis yielded height to be the only significant predictor of footprint dimension from which predictive equations were drawn.

Conclusions

Height was found to be the most significant predictor of footprint dimensions in our patients. The predictive equations and graphs can aid in preoperative surgical decision making resulting in a more anatomical ACL reconstruction and improve the post-operative results.

Harvest location has a minimal impact on differences in cross-sectional area of quadriceps tendon in anterior cruciate ligament reconstruction

PURPOSE

Anterior cruciate ligament (ACL) reconstruction with quadriceps tendon (QT) has been gaining popularity. However, it is unknown how differences in harvest location of the QT affect its thickness and cross-sectional area (CSA). The present study aimed to clarify the differences in thickness and CSA of the QT based on location of tendon harvesting.

METHODS

Patients scheduled for, or who underwent, ACL reconstruction were prospectively included in the study. The short-axis images on ultrasound were used to assess the CSA of the QT at 30 and 60 mm proximal to the superior pole of the patella. QT autografts with CSAs greater than or equal to 10 mm of width were included and measured at three different locations, namely the center, medial one-third, and lateral one-third at the widest diameter of the QT. Patients with less than 10-mm width of the QT at 60 mm proximal to the superior pole of the patella were excluded. The thickness and CSA were compared based on the location of tendon harvest.

RESULTS

Thirty-seven patients were recruited for the study. The mean thickness and CSA were larger in the center of the QT compared to the lateral one-third at 30 mm proximal to the superior pole of the patella (thickness, 6.7 ± 1.3 mm vs. 5.9 ± 1.3 mm; P = 0.009; CSA, 65.6 ± 11.4 mm2 vs. 58.8 ± 11.9 mm2; P = 0.036). There were no significant differences in thickness and CSA of the QT among the three assessment locations at 60 mm proximal to the superior pole of the patella (n.s.).

CONCLUSION

The thickness and CSA of QT was greater in the center compared to the lateral one-third at 30 mm proximal to the QT insertion point. However, the difference in value was clinically non-significant, and therefore, harvest location of the QT autograft may not meaningfully impact intraoperative graft diameter. As a result, surgeons may choose the harvest location without concern for resultant graft diameter as long as the enough length of QT is secured.

LEVEL OF EVIDENCE

III.

Anatomic anterior cruciate ligament reconstruction: Freddie Fu's paradigm

Anterior cruciate ligament (ACL) reconstruction techniques have evolved over the past four decades. There is evidence that non-anatomic reconstruction techniques, such as traditional transtibial drilling, fail to recreate the native anatomy of the ACL, which can lead to increased rotatory knee instability, revision risk, and post-traumatic osteoarthritis. Anatomic ACL reconstruction has emerged as the gold standard, with the goal of restoring the patient's native anatomy and knee kinematics. This review will summarise the relevant anatomy, modern anatomic ACL reconstruction techniques, and literature supporting anatomic ACL reconstruction as the new paradigm. LEVEL OF EVIDENCE: Level V, review article.

Current trends in the anterior cruciate ligament part 1: biology and biomechanics

A trend within the orthopedic community is rejection of the belief that "one size fits all." Freddie Fu, among others, strived to individualize the treatment of anterior cruciate ligament (ACL) injuries based on the patient's anatomy. Further, during the last two decades, greater emphasis has been placed on improving the outcomes of ACL reconstruction (ACL-R). Accordingly, anatomic tunnel placement is paramount in preventing graft impingement and restoring knee kinematics. Additionally, identification and management of concomitant knee injuries help to re-establish knee kinematics and prevent lower outcomes and registry studies continue to determine which graft yields the best outcomes. The utilization of registry studies has provided several large-scale epidemiologic studies that have bolstered outcomes data, such as avoiding allografts in pediatric populations and incorporating extra-articular stabilizing procedures in younger athletes to prevent re-rupture. In describing the anatomic and biomechanical understanding of the ACL and the resulting improvements in terms of surgical reconstruction, the purpose of this article is to illustrate how basic science advancements have directly led to improvements in clinical outcomes for ACL-injured patients.Level of evidenceV.

Preoperative ultrasound predicts the intraoperative diameter of the quadriceps tendon autograft more accurately than preoperative magnetic resonance imaging for anterior cruciate ligament reconstruction

PURPOSE

Sizing of potential autografts is essential to match the native anterior cruciate ligament (ACL) dimensions when performing ACL reconstruction (ACLR). We aimed to investigate the accuracy and reliability of the thickness and cross-sectional area (CSA) assessments for the prediction of the intraoperative diameter of the QT autograft using preoperative ultrasound and MRI.

METHODS

Thirty patients (mean age ± standard deviation, 19.9 ± 5.0 years), who underwent ACLR using QT autograft, were included. The maximum thickness of the QT was assessed at 15 and 30 mm proximal using ultrasound with a long axis image, and at 15 mm proximal to the superior pole of the patella using MRI with a sagittal image. The CSA was assessed at the central 10 mm of the medial-lateral QT width at 30 mm proximal using ultrasound with a short axis image, and at 15 mm proximal to the superior pole of the patella using MRI with an axial image. Intraoperatively, QT autograft was harvested with a 10 mm width and the diameter was measured using a graft sizing device.

RESULTS

Intra- and inter-observer reliabilities of all measurements using ultrasound and MRI were good (Intra-class correlation coefficient, 0.720-0.941). Correlation coefficient with the intraoperative diameter of the QT autograft was higher in ultrasound (R = 0.738-0.791, P < 0.001) than MRI (R = 0.449-0.543, P = 0.002-0.013).

CONCLUSIONS

Preoperative ultrasound predicted the intraoperative diameter of the QT autograft more accurately than MRI. Ultrasound may be used clinically to assure a sufficiently large QT autograft diameter to match the diameter of the patient's native ACL.

LEVEL OF EVIDENCE

Level III.

Reliability of Anatomic Bony Landmark Localization of the ACL Femoral Footprint Using 3D MRI

Background:

Nonanatomic placement of anterior cruciate ligament (ACL) grafts is a leading cause of ACL graft failure. Three-dimensional (3D) magnetic resonance imaging (MRI) femoral footprint localization could enhance planning for an ACL graft's position.

Purpose:

To determine the intra- and interobserver reliability of measurements of the ACL femoral footprint position and size obtained from 3D MRI scans.

Study Design:

Cohort study; Level of evidence, 3.

Methods:

A total of 41 patients with complete ACL tears were recruited between November 2014 and May 2016. Preoperatively, a coronal-oblique proton-density fast spin echo 3D acquisition of the contralateral uninjured knee was obtained along the plane of the ACL using a 1.5T MRI scanner. ACL footprint parameters were obtained independently by 2 musculoskeletal radiologists (observers A and B). The distal and anterior positions of the center of the footprint were measured relative to the apex of the deep cartilage at the posteromedial aspect of the lateral femoral condyle, and the surface area of the ACL femoral footprint was approximated from multiplanar reformatted images. After 1 month, the measurements were repeated. Intraclass correlation coefficients (ICCs) were calculated to assess for intra- and interobserver reliability. Bland-Altman plots were produced to screen for potential systematic bias in measurement and to calculate limits of agreement.

Results:

The ICCs for intraobserver reliability of the ACL femoral distal and anterior footprint coordinates were 0.75 and 0.78, respectively, for observer A. For observer B, they were 0.75 and 0.74, respectively. The ICCs for interobserver reliability were 0.75 and 0.85 for the distal and anterior coordinates, respectively. Bland-Altman plots demonstrated no significant systematic bias. For surface area measurements, the intraobserver ICCs were 0.37 and 0.62 for observers A and B, respectively. The interobserver reliability was 0.60. Observer B consistently measured the footprints as slightly larger versus observer A (1.19 ± 0.27 vs 1 ± 0.22 cm², respectively; P < .001).

Conclusion:

Locating the center of the anatomic footprint of the ACL with 3D MRI showed substantial intra- and interobserver agreement. Interobserver agreement for the femoral footprint surface area was fair to moderate.

ANATOMICAL STUDY OF THE POSTEROLATERAL LIGAMENT COMPLEX OF THE KNEE: LCL AND POPLITEUS TENDON

Objective:

To analyse the distances between the femoral insertions of the popliteus tendon (PT) and the lateral collateral ligament (LCL) through dissections of cadaveric specimens in a mixed population.

Methods:

Fresh cadavers were dissected, and the anthropometric data of all specimens were recorded. The distances from the origin of the PT to the LCL in the femoral region and the diameter of each structure were measured using a digital calliper.

Results:

In total, 11 unpaired knees were dissected, eight men and three women, with an average age of 71.5 ± 15.2 years, weight of 57.2 ± 15.6 kg, and a mean height of 170.5 ± 8.2 cm. The distance from the center of the femoral footprint of the LCL to the PT was 10.0 ± 2.4 mm. The distances between the edges closest to each other and those more distant from each other were 3.1 ± 1.1 mm and 16.3 ± 2.4 mm, respectively.

Conclusion:

The distance between the midpoints of the PT and the LCL in our mixed population is smaller than the distances often reported in the literature. PLC reconstruction with separate tunnels for the LCL and PT may not be technically possible for individuals of any population.Level of Evidence III, Diagnostic studies.

In situ cross-sectional area of the quadriceps tendon using preoperative magnetic resonance imaging significantly correlates with the intraoperative diameter of the quadriceps tendon autograft

PURPOSE

Preoperative assessment to determine the sizes of potential autografts is necessary for individualized anterior cruciate ligament reconstruction (ACLR). However, no study has investigated the prediction of the intraoperative diameter of the quadriceps tendon (QT) autograft based upon preoperative imaging. This study investigated the correlation between the intraoperative diameter of a QT autograft and in situ thickness or cross-sectional area (CSA) measured using preoperative MRI.

METHODS

Thirty-one knees of 31 patients (mean age 20.9 ± 5.0 years) who underwent individualized anatomic ACLR using all soft tissue QT autograft were included retrospectively. At 15 mm proximal to the superior pole of the patella, the maximum QT thickness was assessed in the sagittal plane and the CSA was assessed at the central 10 mm of the QT in the axial plane. The angle between the axial plane and a line perpendicular to the QT longitudinal axis was used to calculate an adjusted CSA using a cosine function. Intraoperatively, each QT autograft was harvested with 10 mm width and the diameter was measured using a graft sizing device.

RESULTS

Intra- and inter-observer reliabilities of all measurements using preoperative MRI were excellent (intra-class correlation coefficient, 0.833-0.970). Significant correlations were observed between the thickness, CSA, or adjusted CSA, and the intraoperative diameter (R = 0.434, 0.607, and 0.540, respectively; P < 0.05).

CONCLUSIONS

The CSA correlated most strongly with the QT autograft diameter. For individualized anatomic ACLR, measuring in situ CSA can be useful for preoperative planning of appropriate graft choices prior to surgery.

LEVEL OF EVIDENCE

III.

Analysis of modified double-bundle anterior cruciate ligament reconstruction with implantless fixation on tibial side

PURPOSE

To avoid potential problems of double-bundle anterior cruciate ligament reconstruction (ACLR), various modifications have been reported. This study analyzed a novel technique of modified double-bundle (MDB) ACLR without implant on tibial side in comparison to single-bundle (SB) ACLR.

METHODS

Eighty cases of isolated anterior cruciate ligament tear (40 each in SB group or MDB group) were included. SB ACLR was performed by outside in technique with quadrupled hamstring graft fixed with interference screws. In MDB group, ACLR harvested tendons were looped over each other at the center and free ends whipstitched. Femoral tunnel was created by outside in technique. Anteromedial tibial tunnel was created with tibial guide at 55°. The anatomic posterolateral aiming guide (Smith-Nephew) was used to create posterolateral tunnel. With the help of shuttle sutures, the free end of gracillis was passed through posterolateral tunnel to femoral tunnel followed by semitendinosus graft through anteromedial tunnel to femoral tunnel. On tibial side the graft was looped over bone-bridge between external apertures of anteromedial and posterolateral tunnel. Graft was fixed with interference screw on femoral side in 10° knee flexion. International Knee Documentation Committee (IKDC), Tegner score, Pivot shift and knee laxity test (KLT, Karl-Storz) were recorded pre- and post-surgery. At one year magnetic resonance imaging (MRI) was done. Statistical analysis was done by SPSS software.

RESULTS

Mean preoperative KLT reading of (10.00 ± 1.17) mm in MDB group improved to (4.10 ± 0.56) mm and in SB group it improved from (10.00 ± 0.91) mm to (4.80 ± 0.46) mm. The mean preoperative IKDC score in MDB group improved from (49.49 ± 8.00) to (92.5 ± 1.5) at one year and that in SB group improved from (52.5 ± 6.9) to (88.4 ± 2.6). At one-year 92.5% cases in MDB group achieved their preinjury Tegner activity level as compared to 60% in SB group. The improvement in IKDC, KLT and Tegner scale of MDB group was superior to SB group. MRI confirmed graft integrity at one year and clinically at 2 years.

CONCLUSION

MDB ACLR has shown better outcome than SB ACLR. It is a simple technique that does not require fixation on tibial side and resultant graft is close to native ACL.

Introducing the Lateral Femoral Condyle Index as a Risk Factor for Anterior Cruciate Ligament Injury

BACKGROUND

The asymmetry of the medial and lateral knee compartments contributes significantly to femorotibial biomechanics and pivoting, and it is reported to be a relevant risk factor for an anterior cruciate ligament (ACL) injury.

PURPOSE

(1) To assess the role of femoral condyle sphericity as a risk factor for an ACL rupture and rerupture. (2) To compare the new risk factor with existing bony morphological risk factors via magnetic resonance imaging (MRI) and to assess the most predictive risk factor for an ACL rupture.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

A retrospective case-control study of 60 patients was conducted. Three age- and sex-matched cohorts (each n = 20) were analyzed: ACL reruptures, primary ACL ruptures, and a control group consisting of isolated meniscal tears or patients with anterior knee pain without signs of trochlear dysplasia. The lateral femoral condyle index (LFCI) as a novel MRI measurement was developed to quantify femoral sphericity. In addition, previously known MRI risk factors associated with ACL injury were analyzed (notch width index, medial tibial slope, lateral tibial slope, medial tibial depth, and lateral tibial height). Differences among groups were compared; cutoff values were defined; and diagnostic performance of the risk factors was assessed. The risk factors were subsequently analyzed with multiple logistic regression.

RESULTS

The LFCI was significantly smaller in knees with ACL reruptures (median, 0.67; range, 0.59-0.75) and primary ACL ruptures (0.67; range, 0.60-0.75) than in the control group (0.76; range, 0.6-0.81; P < .01). The LFCI yielded the highest area under the curve among the analyzed risk factors: 0.82 (95% CI, 0.7-0.9). A cutoff of 0.70 yielded a sensitivity of 78% and a specificity of 80% to predict an ACL rupture or rerupture (odds ratio, 13.79; 95% CI, 3.67-51.75). In combination with lateral tibial height (cutoff, 3.8 mm) and lateral tibial slope (cutoff, 2.9°), the diagnostic performance was improved. The area under the curve was 0.86 (95% CI, 0.75-0.94), with a sensitivity of 90% and a specificity of 70% (odds ratio, 21.00; 95% CI, 5.10-85.80).

CONCLUSION

A decreased LFCI is associated with an ACL injury. The LFCI, lateral tibial height, and lateral tibial slope are the most predictive risk factors for an ACL injury. These findings might aid clinicians in identifying patients at risk for an ACL injury and inform the patient after reconstruction for a higher risk of rerupture.

Size and Shape of the Human Anterior Cruciate Ligament and the Impact of Sex and Skeletal Growth: A Systematic Review

BACKGROUND

High rates of anterior cruciate ligament (ACL) injury and surgical reconstruction in both skeletally immature and mature populations have led to many studies investigating the size and shape of the healthy ligament. The purposes of the present study were to compile existing quantitative measurements of the geometry of the ACL, its bundles, and its insertion sites and to describe effects of common covariates such as sex and age.

METHODS

A search of the Web of Science was conducted for studies published from January 1, 1900, to April 11, 2018, describing length, cross-sectional area, volume, orientation, and insertion sites of the ACL. Two reviewers independently screened and reviewed the articles to collect quantitative data for each parameter.

RESULTS

Quantitative data were collected from 92 articles in this systematic review. In studies of adults, reports of average ACL length, cross-sectional area, and volume ranged from 26 to 38 mm, 30 to 53 mm, and 854 to 1,858 mm, respectively. Reported values were commonly found to vary according to sex and skeletal maturity as well as measurement technique.

CONCLUSIONS

Although the geometry of the ACL has been described widely in the literature, quantitative measurements can depend on sex, age, and measurement modality, contributing to variability between studies. As such, care must be taken to account for these factors. The present study condenses measurements describing the geometry of the ACL, its individual bundles, and its insertion sites, accounting for common covariates when possible, to provide a resource to the clinical and scientific communities.

CLINICAL RELEVANCE

Quantitative measures of ACL geometry are informative for developing clinical treatments such as ACL reconstruction. Age and sex can impact these parameters.

Measurement of the Whole and Midsubstance Femoral Insertion of the Anterior Cruciate Ligament: The Comparison with the Elliptically Calculated Femoral Anterior Cruciate Ligament Footprint Area

PURPOSE

The purpose of this study was to measure the detailed morphology of the femoral anterior cruciate ligament (ACL) footprint. The correlation and the comparison between the measured area and the area which mathematically calculated as elliptical were also evaluated.

MATERIALS AND METHODS

Thirty nine nonpaired 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. The ACL was carefully dissected, and the periphery of the ACL insertion site was outlined on both the whole footprint and the midsubstance insertion. Lateral view of the femoral condyle was photographed with a digital camera, and the images were downloaded to a personal computer. The area, length, and width of the femoral ACL footprint were measured with Image J software (National Institution of Health). Using the length and width of the femoral ACL footprint, the elliptical area was calculated as 0.25 π (length × width). Statistical analysis was performed to reveal the correlation and the comparison of the measured and elliptically calculated area.

RESULTS

The sizes of the whole and midsubstance femoral ACL footprints were 127.6 ± 41.7 mm² and 61 ± 20.2 mm², respectively. The sizes of the elliptically calculated whole and midsubstance femoral ACL footprints were 113.9 ± 4.5 mm² and 58.4 ± 3 mm², respectively. Significant difference was observed between the measured and the elliptically calculated area. In the midsubstance insertion, significant correlation was observed between the measured and the elliptically calculated area (Pearson's correlation coefficient = 0.603, P = 0.001). However, no correlation was observed in the whole ACL insertion area.

CONCLUSION

The morphology of the femoral ACL insertion resembles an elliptical shape. However, due to the wide variation in morphology, the femoral ACL insertion cannot be considered mathematically elliptical.

Individualized Anterior Cruciate Ligament Graft Matching: In Vivo Comparison of Cross-sectional Areas of Hamstring, Patellar, and Quadriceps Tendon Grafts and ACL Insertion Area

BACKGROUND

Recent literature correlated anterior cruciate ligament (ACL) reconstruction failure to smaller diameter of the harvested hamstring (HS) autograft. However, this approach may be a simplification, as relation of graft size to native ACL size is not typically assessed and oversized grafts may impart their own complications.

PURPOSE

To evaluate in vivo data to determine if the commonly used autografts reliably restore native ACL size.

STUDY DESIGN

Descriptive laboratory study.

METHODS

Intraoperative data of the tibial insertion area and HS graft diameter were collected and retrospectively evaluated for 46 patients who underwent ACL reconstruction with HS autografts. Magnetic resonance imaging measurements of the cross-sectional area (CSA) of the possible patellar tendon (PT) and quadriceps tendon (QT) autografts were also done for each patient. The percentages of tibial insertion site area restored by the 3 possible grafts were then calculated and compared for each individual.

RESULTS

The mean ACL tibial insertion area was 107.2 mm² (60.5-155.5 mm²). The mean CSAs of PT, HS, and QT were 33.2, 55.3, and 71.4 mm², respectively. When all grafts were evaluated, the percentage reconstruction of the insertion area varied from 16.2% to 123.1% on the tibial site and from 25.5% to 176.7% on the femoral site, differing significantly for each graft type ( P < .05). On average, 32.8% of the tibial insertion area would have been filled with PT, 53.6% by HS, and 69.5% by QT. Based on previous cadaveric studies indicating that graft size goal should be 50.2% ± 15% of the tibial insertion area, 82.7% of patients in the HS group were within this range (36.9%, QT; 30.5%, PT), while 65.2% in the PT group were below it and 60.9% in the QT group were above it.

CONCLUSION

ACL insertion size and the CSAs of 3 commonly used grafts vary greatly for each patient and are not correlated with one another. Thus, if the reconstructed ACL size is determined by the harvested autograft size alone, native ACL size may not be adequately restored. PT grafts tended to undersize the native ACL, while QT might oversize it.

CLINICAL RELEVANCE

These results may help surgeons in preoperative planning, as magnetic resonance imaging measurements can be helpful in determining individualized graft choice to adequately restore the native ACL.

A Preoperative Planning Tool: Aggregate Anterior Approach to the Humerus With Quantitative Comparisons

Extensile approaches to the humerus are often needed when treating complex proximal or distal fractures that have extension into the humeral shaft or in those fractures that occur around implants. The 2 most commonly used approaches for more complex fractures include the modified lateral paratricipital approach and the deltopectoral approach with distal anterior extension. Although the former is well described and quantified, the latter is often associated with variable nomenclature with technical descriptions that can be confusing. Furthermore, a method to expose the entire humerus through an anterior extensile approach has not been described. Here, we illustrate and quantify a technique for connecting anterior humeral approaches in a stepwise fashion to form an aggregate anterior approach (AAA). We also describe a method for further distal extension to expose 100% of the length of the humerus and compare this approach with both the AAA and the lateral paratricipital in terms of access to critical bony landmarks, as well as the length and area of bone exposed.

Increased incidence of anterior cruciate ligament revision surgery in paediatric verses adult population

PURPOSE

To evaluate the anterior cruciate ligament graft failure rate in a population of 1376 patients submitted to single-bundle anterior cruciate ligament reconstruction procedure. It was hypothesized that the younger the patient, the greater the chance of a new anterior cruciate ligament graft ligament injury.

METHODS

A retrospective chart review was performed on patients who had SB anterior cruciate ligament reconstruction between the years, 2001 and 2016, with a minimum post-operative follow-up period of 6 months. The patient population was divided into three groups, according to age: group 1-under 16 years old; group 2-between 16 and 18 years old; and group 3-older than 18 years old. Data collected included sex, laterality and graft choice data.

RESULTS

In group 1 (under 16 years old), there were 61 primary ACL surgeries performed and 15 (24.6%) revision ACL surgeries. In group 2 (between 16 and 18 years old), there was 57 primary ACL procedures, of which 10 (17.5%) were revisions. In the group 3 (older than 18 years of age), 1258 surgeries were done with 116 (9.2%) revisions.

CONCLUSION

The rate of ACL revision surgery in patients under 16 years of age was significantly higher than that found in patients older than 18 years old. When compared to the population between 16 and 18 years old, there were a higher number of failure cases, however, statistically non-significant.

LEVEL OF EVIDENCE

IV.

The intercondylar notch ceiling: an accurate reference for distal femoral resection in total knee arthroplasty for severely degenerated varus knees

PURPOSE

To measure the distance from the intercondylar ceiling to the lowest point of the medial and lateral femoral condyles in a healthy population so to obtain a clearly discernible and accurate landmark for proper distal femoral resection during total knee arthroplasty (TKA).

METHODS

Three-dimensional models of the lower extremities of 100 healthy Chinese subjects were constructed using computed tomography scans. The distance between the distal surface of the medial femoral condyle and the intercondylar notch ceiling, in the direction of the femoral mechanical axis, was measured.

RESULTS

The mean distance from the distal surface of the medial femoral condyle to the intercondylar notch ceiling was 9.1 ± 1.4 and 8.2 ± 1.4 mm in male and female subjects, respectively. Interestingly, this distance did not differ significantly with varying sizes of the distal femur.

CONCLUSIONS

The intercondylar notch ceiling could be used as an accurate landmark to determine the proper distal femoral resection level during TKA. For the clinical relevance, the distal femoral bone cut should be at the level of the intercondylar notch ceiling when using the most of the current TKA prosthesis systems.

Radiographic femoral bicondylar width predicts anterior cruciate ligament insertion site sizes

PURPOSE

The purpose of this study was to determine whether radiographic femoral bicondylar width predicts intra-operative anterior cruciate ligament (ACL) insertion site sizes.

METHODS

Seventy-three consecutive patients (39 males and 34 females; mean age 25.2 years ± 10.2) who underwent anatomic ACL reconstruction were retrospectively reviewed. Femoral condyle width was measured using a pre-operative anteroposterior (AP) radiograph of the operative knee. Lines were drawn through the anatomic axis of the femur, as well as perpendicularly through the condyles. Bicondylar width was measured as the maximum width across both the medial and lateral femoral condyles utilizing this perpendicular line. The ACL insertion site lengths (in the AP direction) of both the tibia and the femur were measured intra-operatively using a commercially available arthroscopic ruler.

RESULTS

The average bicondylar width was significantly smaller for females compared to males (p < 0.05). The average tibial and femoral insertion site sizes were significantly smaller for females compared to males (p < 0.05). Regression analysis predicted tibial (r ² = 0.88) and femoral (r ² = 0.90) insertion site sizes based on femoral bicondylar width measurements.

CONCLUSION

A simple radiographic measurement of femoral bicondylar width can predict intra-operative tibial and femoral insertion site sizes, which has the potential to assist surgeons in performing individualized ACL reconstruction in cases where MRI scan is unavailable.

LEVEL OF EVIDENCE

IV.

Blumensaat's line is not always straight: morphological variations of the lateral wall of the femoral intercondylar notch

PURPOSE

The purpose of this study was to evaluate the morphological variations of the lateral wall of the femoral intercondylar notch.

METHODS

Fifty-two non-paired human cadaver knees were used. All soft tissues around the knee were resected except the ACL. The ACL was cut in the middle, and the femoral bone was cut at the most proximal point of the femoral notch parallel to the plane of the femoral bone shaft. The ACL was carefully dissected, and the periphery of the ACL insertion site was outlined on the femoral side. An accurate lateral view of the femoral condyle was photographed with a digital camera, and the images were downloaded to a personal computer. The morphological variations of Blumensaat's line, the height and area of the lateral wall of the femoral intercondylar notch and the size of the femoral ACL footprints were measured with Image J software.

RESULTS

Blumensaat's line exhibited three types of morphological variations. A straight line was observed in 19 knees (37 %) (straight type). A protrusion spanning less than half of the line was observed at the proximal part of Blumensaat's line in 10 knees (19 %) (small hill type). A protrusion spanning more than half of the line was observed at the proximal part of the line in 23 knees (44 %) (large hill type). In some knees with this large hill type variation, the appearance was similar to that of anterior spur. No significant differences between these three types were observed in either the height and area of the lateral wall of the femoral intercondylar notch or the area of the femoral ACL footprint.

CONCLUSION

In conclusion, Blumensaat's line has three types of morphological variations (straight, small hill and large hill types). For the 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 for the use of Quadrant method. The grid placement of Quadrant method would be changed in the knees of these type variations.

Tibial ACL insertion site length: correlation between preoperative MRI and intra-operative measurements

PURPOSE

This study was undertaken primarily to identify the tibial insertion site length of ruptured ACL fibres in patients undergoing primary ACL reconstruction. A secondary aim was to evaluate the correlation of pre- and intra-operative measurements.

METHODS

In 146 patients undergoing primary ACL reconstruction, a preoperative measurement on MRI of the tibial ACL insertion site length was taken by two raters and then compared with single surgeon's intra-operative measurements using a specialized ruler. Inclusion criteria were primary ACL reconstruction and MRI performed within 3 months prior to surgery on one specific MRI machine at the study centre. Inter-rater and intra-rater reliability based on intra class correlation (ICC) was calculated. Additionally, correlation between preoperative and postoperative measurements and the anthropometric data was assessed using Pearson correlation.

RESULTS

The tibial ACL insertion site had a mean length of 16.6 ± 1.6 mm (11.9-21.0) as measured by MRI, and 16.4 ± 1.6 mm (11.0-20.0) as measured intra-operatively. The ICCs for intra- and inter-rater reliability of the MRI measurements were 0.99 (95 % CI 0.97; 0.99; p < 0.001) and 0.81 (95 % CI 0.75; 0.86; p < 0.001), respectively. Regression analysis demonstrated, after controlling for subject height and weight, that the MRI measurements significantly predicted intra-operative measurement of tibial insertion site length (β = 0.796; R (2)-change 0.77; p < 0.001).

CONCLUSION

Preoperative measurement of the tibial ACL length is possible using MRI and can be a valuable aid in more efficient preoperative planning given the knowledge of expected dimensions of special knee structures.

LEVEL OF EVIDENCE

III.

Anatomic placement of the femoral tunnel by a modified transtibial technique using a large-offset femoral tunnel guide: A cadaveric study

BACKGROUND

The purpose of this study was to assess whether the use of a 10 mm-offset femoral tunnel guide with lateral rotation allows more anatomic placement of femoral tunnel compared to the conventional seven millimeters-offset guide in transtibial anterior cruciate ligament (ACL) reconstruction.

METHODS

Sixteen knees from eight cadavers were employed. Four guide pins were inserted using a seven millimeters- or 10mm-offset transtibial femoral tunnel guide with or without lateral rotation technique in each knee. The pin positions were assessed by the quadrant method. Femoral tunnels were then reamed along the guide pins inserted through the laterally rotated guides: seven millimeters-offset for right knees and 10 mm- offset for left knees. The percentages of the coverage of native ACL femoral footprints were analyzed.

RESULTS

Lateral rotation of the seven millimeters- & 10mm-offset guides placed the pins more posteriorly (lower) by 15.7% and 24.5%, respectively (p<0.001). Laterally rotated 10 mm-offset guides placed the guide pins more distally by 6.2% and more posteriorly by 6.6% than laterally rotated seven millimeters-offset guides. Laterally rotated seven millimeters- & 10 mm-offset guides resulted in average coverage of 52.3% and 61.8% of the native ACL femoral footprints, respectively (p<0.001). The lengths of the tunnels were acceptable.

CONCLUSION

Compared to the conventional seven millimeters-offset guide, the use of a 10mm-offset femoral tunnel guide with lateral rotation allows more anatomic placement of femoral tunnel in transtibial ACL reconstruction.

CLINICAL RELEVANCE

Anatomic single bundle ACL reconstruction by transtibial technique seems feasible by using the technique described in this study.

A Quantitative Exposure Planning Tool for Surgical Approaches to the Sacroiliac Joint

OBJECTIVES

To aid in surgical planning by quantifying and comparing the osseous exposure between the anterior and posterior approaches to the sacroiliac joint.

METHODS

Anterior and posterior approaches were performed on 12 sacroiliac joints in 6 fresh-frozen torsos. Visual and palpable access to relevant surgical landmarks was recorded. Calibrated digital photographs were taken of each approach and analyzed using Image J.

RESULTS

The average surface areas of exposed bone were 44 and 33 cm for the anterior and posterior approaches, respectively. The anterior iliolumbar ligament footprint could be visualized in all anterior approaches, whereas the posterior aspect could be visualized in all but one posterior approach. The anterior approach provided visual and palpable access to the anterior superior edge of the sacroiliac joint in all specimens, the posterior superior edge in 75% of specimens, and the inferior margin in 25% and 50% of specimens, respectively. The inferior sacroiliac joint was easily visualized and palpated in all posterior approaches, although access to the anterior and posterior superior edges was more limited. The anterior S1 neuroforamen was not visualized with either approach and was more consistently palpated when going posterior (33% vs. 92%).

CONCLUSIONS

Both anterior and posterior approaches can be used for open reduction of pure sacroiliac dislocations, each with specific areas for assessing reduction. In light of current plate dimensions, fractures more than 2.5 cm lateral to the anterior iliolumbar ligament footprint are amenable to anterior plate fixation, whereas those more medial may be better addressed through a posterior approach.

Technique of anatomical single bundle ACL reconstruction with rounded rectangle femoral dilator

BACKGROUND

This study aimed to present a new technique for anatomical single bundle anterior cruciate ligament (ACL) reconstruction. We developed an original rounded rectangular dilator set to create rounded rectangular femoral tunnels. This technique can increase the femoral tunnel size without roof impingement, and has the potential to reduce the graft failure rate. We investigated the tunnel position and the incidence of intraoperative complications.

METHOD

The presented technique is anatomical single bundle ACL reconstruction using a semitendinosus graft (with or without the gracilis tendon). The tunnel was drilled via an additional medial portal. Rounded rectangular tunnels were created using a special dilator. Tibial tunnels were created using conventional rounded tunnels. Fixation was achieved using a suspensory device on the femoral side and a plate and screw on the tibial side.

PATIENTS

Fifty patients underwent this surgery, and intraoperative complications were investigated. The femoral tunnel positions were documented postoperatively from computed tomography scans using the quadrant method. The tibial tunnel positions (anterior-to-posterior, medial-to-lateral) were documented using intraoperative X-ray scans.

RESULTS

Only one patient had a partial posterior tunnel wall blowout. The femoral tunnel length varied between 30 and 40mm (mean, 34.9±3.3mm). All femoral and tibial tunnels were located within the area of the anatomical ACL insertions.

CONCLUSION

We did not experience any serious intraoperative complications during anatomical single bundle ACL reconstruction using a rounded rectangle dilator, and the resulting locations of the femoral and tibial tunnels were within the anatomical ACL footprint.

LEVEL OF EVIDENCE

Level IV.

Quantitative comparison of the microscopic anatomy of the human ACL femoral and tibial entheses

The femoral enthesis of the human anterior cruciate ligament (ACL) is known to be more susceptible to injury than the tibial enthesis. To determine whether anatomic differences might help explain this difference, we quantified the microscopic appearance of both entheses in 15 unembalmed knee specimens using light microscopy, toluidine blue stain and image analysis. The amount of calcified fibrocartilage and uncalcified fibrocartilage, and the ligament entheseal attachment angle were then compared between the femoral and tibial entheses via linear mixed-effects models. The results showed marked differences in anatomy between the two entheses. The femoral enthesis exhibited a 3.9-fold more acute ligament attachment angle than the tibial enthesis (p<0.001), a 43% greater calcified fibrocartilage tissue area (p<0.001), and a 226% greater uncalcified fibrocartilage depth (p<0.001), with the latter differences being particularly pronounced in the central region. We conclude that the ACL femoral enthesis has more fibrocartilage and a more acute ligament attachment angle than the tibial enthesis, which provides insight into why it is more vulnerable to failure.

Proportional evaluation of anterior cruciate ligament footprint size and knee bony morphology

PURPOSE

The purpose of this study was to reveal the correlation in size between the native anterior cruciate ligament (ACL) footprint and the femoral intercondylar notch and the tibia plateau, and to calculate the proportion in size between the ACL footprint and knee bony morphology.

METHODS

Twenty-six non-paired human cadaver knees were used. All soft tissues around the knee were resected except the ACL. 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 periphery of the ACL insertion site was outlined on both the femoral and tibial sides. An accurate lateral view of the femoral condyle and an axial view of the tibial plateau were photographed with a digital camera, and the images were downloaded to a personal computer. The size of the femoral and tibial ACL footprints and the area of the lateral wall of the intercondylar notch and the tibia plateau were measured with Image J software (National Institution of Health).

RESULTS

The sizes of the native femoral and tibial ACL footprints were 69.8 ± 25 and 133.8 ± 31.3 mm(2), respectively. The areas of the lateral wall of the intercondylar notch and the tibia plateau were 390.5 ± 70.5 and 2,281.7 ± 377.3 mm(2), respectively. The femoral ACL footprint area and the area of the lateral wall of the femoral intercondylar notch (Pearson's correlation coefficient = 0.603, p = 0.001), and the tibial ACL footprint area and the area of the tibia plateau (Pearson's correlation coefficient = 0.452, p = 0.02) both showed significant correlation. The femoral ACL footprint was 17.8 ± 4.9 %, the size of the lateral wall of the femoral intercondylar notch, and the tibial ACL footprint was 5.9 ± 1.3 %, the size of the tibia plateau.

CONCLUSION

For clinical relevance, the femoral ACL footprint is approximately 18 %, the size of the intercondylar notch, and the tibial ACL footprint is approximately 6 %, the size of the tibia plateau. It might be possible to predict the size of the ACL measuring these parameters preoperatively.

Evaluating the distance between the femoral tunnel centers in anatomic double-bundle anterior cruciate ligament reconstruction using a computer simulation

Purpose

We aimed to clarify the distance between the anteromedial (AM) bundle and posterolateral (PL) bundle tunnel-aperture centers by simulating the anatomical femoral tunnel placement during double-bundle anterior cruciate ligament reconstruction using 3-D computer-aided design models of the knee, in order to discuss the risk of tunnel overlap. Relationships between the AM to PL center distance, body height, and sex difference were also analyzed.

Patients and methods

The positions of the AM and PL tunnel centers were defined based on previous studies using the quadrant method, and were superimposed anatomically onto the 3-D computer-aided design knee models from 68 intact femurs. The distance between the tunnel centers was measured using the 3-D DICOM software package. The correlation between the AM–PL distance and the subject’s body height was assessed, and a cutoff height value for a higher risk of overlap of the AM and PL tunnel apertures was identified.

Results

The distance between the AM and PL centers was 10.2±0.6 mm in males and 9.4±0.5 mm in females (P<0.01). The AM–PL center distance demonstrated good correlation with body height in both males (r=0.66, P<0.01) and females (r=0.63, P<0.01). When 9 mm was defined as the critical distance between the tunnel centers to preserve a 2 mm bony bridge between the two tunnels, the cutoff value was calculated to be a height of 160 cm in males and 155 cm in females.

Conclusion

When AM and PL tunnels were placed anatomically in simulated double-bundle anterior cruciate ligament reconstruction, the distance between the two tunnel centers showed a strong positive correlation with body height. In cases with relatively short stature, the AM and PL tunnel apertures are considered to be at a higher risk of overlap when surgeons choose the double-bundle technique.

Double intramedullary cortical button versus suture anchors for distal biceps tendon repair: a biomechanical comparison

PURPOSE

The aim of this biomechanical in vitro study was to compare the novel technique of double intramedullary cortical button (DICB) fixation with the well-established method of suture anchor (SA) fixation for distal biceps tendon repair.

METHODS

A matched-pair analysis (24 human cadaveric radii) was performed with respect to cyclic loadings and failure strengths. Twelve specimens per group were cyclically loaded for 1,000 cycles at 1.5 Hz from 5 to 50 N and from 5 to 100 N, respectively. The tendon-bone displacement was optically analysed using the Image J Software (National Institute of Health). Afterwards, all specimens were pulled to failure. Maximum load to failure and mode of failure were recorded.

RESULTS

All DICB constructs passed the cyclic loading test, whereas 4 of the 12 specimens within the SA group failed by anchor pull-out. Cyclic loading showed a mean tendon-bone displacement of 0.6 ± 1.4 mm for the DICB group and 1.4 ± 1.4 mm for the SA group (n.s.) after 1,000 cycles with 50 N, and a mean displacement of 2.1 ± 2.4 mm for the DICB group and 3.5 ± 3.7 mm for the SA group (n.s.) after 1,000 cycles with 100 N. Load to failure testing showed a mean failure load of 312 ± 76 N and a stiffness of 67.1 ± 11.7 N/mm for the DICB technique. The mean load to failure for the SA repair was 200 ± 120 N (n.s.) and the stiffness was 55.9 ± 21.3 N/mm (n.s.).

CONCLUSIONS

The novel technique of DICB fixation showed small tendon-bone displacement during cyclic testing and reliable fixation strength to the bone in load to failure. Moreover, all DICB constructs passed cyclic loadings without failure. Based on the current findings, a more aggressive postoperative rehabilitation may be allowed for the DICB repair in clinical use.

Comparison of transtibial and transportal techniques in drilling femoral tunnels during anterior cruciate ligament reconstruction using 3D-CAD models

Purpose

The purpose of this study was to assess the differences in bone tunnel apertures between the trans-accessory medial portal (trans-AMP) technique and the transtibial (TT) technique in double-bundle anterior cruciate ligament reconstruction. The extent of ovalization and the frequency of overlap of the two tunnel apertures were compared.

Methods

The simulation of femoral tunnel drilling with the TT and the trans-AMP techniques was performed using three-dimensional computer aided design models from two volunteers. The incidence angle of drilling against the intercondylar wall, the femoral tunnel position, the ovalization, and the overlap were analyzed. The aperture and location of the tunnels were also examined in real anterior cruciate ligament reconstruction cases (n=36).

Results

The surgical simulation showed that a lower drill incident angle induced by the TT technique made the apertures of two tunnels more ovalized, located anteromedial tunnels in a shallower position to prevent posterior wall blow out, and led to a higher frequency of tunnel overlap. The trans-AMP group had tunnel places within the footprint and had less ovalization and overlap. The results of analysis for tunnels in the clinical cases were consistent with results from the surgical simulation.

Conclusion

In the TT technique, the shallow anteromedial tunnel location and more ovalized tunnel aperture can lead to a higher frequency of tunnel overlap. Compared with the TT technique, the trans-AMP technique was more useful in preparing femoral tunnels anatomically and avoiding tunnel ovalization and overlapping in double-bundle anterior cruciate ligament reconstruction.