Standard Knee Radiographs Research Articles

Variability Between Full-Length Lateral Radiographs and Standard Short Knee Radiographs When Evaluating Posterior Tibial Slope in Revision ACL Patients.

Increased posterior tibial slope (PTS) has been identified as a risk factor for failure after anterior cruciate ligament (ACL) reconstruction. Correction of PTS may improve outcomes after revision ACL reconstruction. There are conflicting reports demonstrating the measurement of the PTS on standard short knee (SSK) radiographs versus full-length lateral (FLL) radiographs including the entire tibia. To compare PTS measurements between SSK and FLL radiographs in patients who failed primary ACL reconstruction. It was hypothesized that there would be high variability between the SSK and FLL radiographic measurements. Cohort study (diagnosis); Level of evidence, 2. The medial and lateral PTS were measured on the SSK and FLL radiographs of 33 patients with failed primary ACL reconstructions. All measurements were performed by 2 trained independent observers (A.A.M., J.S.), and inter- and intraobserver reliability were calculated using the intraclass correlation coefficient (ICC). Measurements recorded by the observer with the higher intraobserver ICC were used for comparison of the PTS on SSK versus FLL radiographs. Both the inter- and the intraobserver reliability values of the PTS measurements were excellent. There was a significant difference in mean PTS on the medial plateau as measured on the SSK and FLL radiographs (11.2°± 5.3° vs 12.5°± 4.6°; P = .03), with the FLL radiographs demonstrating higher PTS. There was also a significant difference in the mean PTS on the lateral plateau as measured on SSK versus FLL radiographs (10.7°± 4.3° vs 12.2°± 4°, respectively; P = .01), with the FLL radiographs demonstrating higher PTS. Notably, 66.67% of the absolute measurements for PTS on the medial plateau differed by ≥2°, with variability as high as 8.5°. Results indicated that FLL and SSK radiographs are not interchangeable measurements for PTS associated with failed ACL reconstruction. Because FLL radiographs demonstrate less variability than SSK radiographs, we recommend obtaining them to evaluate these complex patients.

Deep Learning Artificial Intelligence Tool for Automated Radiographic Determination of Posterior Tibial Slope in Patients With ACL Injury.

An increased posterior tibial slope (PTS) corresponds with an increased risk of graft failure after anterior cruciate ligament (ACL) reconstruction (ACLR). Validated methods of manual PTS measurements are subject to potential interobserver variability and can be inefficient on large datasets. To develop a deep learning artificial intelligence technique for automated PTS measurement from standard lateral knee radiographs. It was hypothesized that this deep learning tool would be able to measure the PTS on a high volume of radiographs expeditiously and that these measurements would be similar to previously validated manual measurements. Cohort study (diagnosis); Level of evidence, 2. A deep learning U-Net model was developed on a cohort of 300 postoperative short-leg lateral radiographs from patients who underwent ACLR to segment the tibial shaft, tibial joint surface, and tibial tuberosity. The model was trained via a random split after an 80 to 20 train-validation scheme. Masks for training images were manually segmented, and the model was trained for 400 epochs. An image processing pipeline was then deployed to annotate and measure the PTS using the predicted segmentation masks. Finally, the performance of this combined pipeline was compared with human measurements performed by 2 study personnel using a previously validated manual technique for measuring the PTS on short-leg lateral radiographs on an independent test set consisting of both pre- and postoperative images. The U-Net semantic segmentation model achieved a mean Dice similarity coefficient of 0.885 on the validation cohort. The mean difference between the human-made and computer-vision measurements was 1.92° (σ = 2.81° [P = .24]). Extreme disagreements between the human and machine measurements, as defined by ≥5° differences, occurred <5% of the time. The model was incorporated into a web-based digital application front-end for demonstration purposes, which can measure a single uploaded image in Portable Network Graphics format in a mean time of 5 seconds. We developed an efficient and reliable deep learning computer vision algorithm to automate the PTS measurement on short-leg lateral knee radiographs. This tool, which demonstrated good agreement with human annotations, represents an effective clinical adjunct for measuring the PTS as part of the preoperative assessment of patients with ACL injuries.

Paper 44: Deep Learning Artificial Intelligence Tool for Automated Radiographic Determination of Posterior Tibial Slope in Patients with Anterior Cruciate Ligament Injuries

Objectives: An increased posterior tibial slope (PTS) corresponds with an increased risk of graft failure following anterior cruciate ligament reconstruction (ACLR). Validated methods of human PTS measurements are subject to interobserver variability and can be inefficient on large-scale sets of images. The purpose of this study is to develop a deep learning artificial intelligence technique for the automated measurement of PTS from standard lateral knee radiographs. Methods: A deep learning U-Net model was developed on a cohort of 300 postoperative short leg lateral radiographs from ACLR patients to segment the tibial shaft, tibial joint surface, and tibial tuberosity. The model was trained via a random split following an 80:20 train-validation scheme. Masks for training images were manually segmented and the model was trained for 400 epochs. An image processing pipeline was then deployed to annotate and measure the PTS using the predicted segmentation masks. Finally, the performance of this combined pipeline was compared to human measurements performed by two study personnel using a previously validated manual technique for measuring PTS on short leg lateral radiographs on an independent test-set consisting of both preoperative and postoperative images. Results: The U-Net semantic segmentation model achieved a mean Dice similarity coefficient of 0.885 on the validation cohort. The mean difference between human-made and computer-vision measurements was 1.92⁰ (σ = 2.81⁰, P=0.24). Extreme disagreements between human and machine measurements as defined by differences ≥5⁰ occurred less than 5% of the time. The model was incorporated into a web based digital application for demonstration purposes which can provide measurement of an uploaded image in portable network graphics format in less than 5 seconds. Conclusions: We developed an accurate and reliable deep learning computer vision algorithm to automate the measurement of PTS on lateral knee radiographs. This tool will be deployed for clinical use on an institution-wide basis and, pending external validation, be made available to outside orthopaedic surgeons. This will provide an efficient and accurate tool to measure PTS during the preoperative assessment of ACL-injured patients.

Comparison of the Tibial Posterior Slope Angle Between the Tibial Mechanical Axis and Various Diaphyseal Tibial Axes After Total Knee Arthroplasty

BackgroundThe posterior tibial slope angle (PTS) is crucial for sagittal alignment after total knee arthroplasty (TKA). This study aimed to determine which PTS based on the lateral view of standard knee radiographs (LSKRs; 36 × 43 cm) reflects the PTS based on a full-length lateral tibial radiograph (FLTR). MethodsA total of 290 patients (355 knees) who underwent primary TKA were retrospectively recruited. Cross-sectional views from the 3-dimensional digital model of the tibial prosthesis and bone complex in the sagittal plane were used as FLTRs and LSKRs. Considering the region 21.5 cm proximal to the site of FLTR as the spot for LSKR to determine the 5 tibial diaphyseal axes, the axis that simulates the PTS as determined by the tibial mechanical axis between the center of the tibial component and the ankle plafond in LSKR was determined and compared. ResultsPTS (α5) defined by the line connecting the midpoints of tibial width between the region 10-cm distal to the knee joint and the distal end of the tibia based on LSKR revealed the least mean difference (0.13° ± 1.00°) and the strongest correlation (P < .001, r = 0.948) with PTS based on FLTR (α0). The number of knees in α5, indicating a difference of <2° from α0, was 333 of 355 (93.8%). The equivalence test results indicated that α0 and α5 were statistically equivalent within a difference of 2° (P < .001). ConclusionsPTS (α5) can be used as a clinically reliable substitution of the true PTS on an FLTR for evaluating sagittal alignment after TKA.

Paper 82: High Variability Exists Between Longstanding Lateral Radiographs and Standard Lateral Knee Radiographs Evaluating Posterior Tibial Slope in Revision ACL Patients

Objectives:Increased posterior tibial slope (PTS) has been identified as a risk factor for both short-term and long-term failure after anterior cruciate ligament (ACL) reconstruction. Correction of PTS may improve outcomes after revision ACL reconstruction. Conflicting reports demonstrate the most accurate way to measure the PTS on standard short knee radiographs versus longstanding lateral radiographs including the entire tibia. Many reports advocate short knee radiographs as adequate for the evaluation of posterior tibial slope and deciding surgical treatment. The purpose of this study was to compare posterior tibial slope measurements between standard short segment knee (SSK) and longstanding lateral knee radiographs (LSL) in a failed ACL cohort. We hypothesize that there is high variability in SSK measurements compared to LSL. Our secondary hypothesis is that our series of surgical deformity corrections for failed ACL reconstructions with increased PTS includes a significant number of biplanar deformities requiring altered technique to completely address all deformities.Methods:The medial and lateral PTS were measured on 35 consecutive patients with failed ACL reconstructions using SSK and LSL using previously published techniques. Coronal plane deformity was assessed by the tibiofemoral angle on AP long standing films. All measurements were made by two trained independent observers at two different times separated by one month for calculation of inter- and intra-observer reliability using intra-class correlation coefficients (ICCs). Measurements recorded by the observer with the higher intra-observer ICC for the SSK and LSL were used for calculation. Paired t-tests were used for direct comparison of tibial slope measurements between the SSK and LSL conditions. P-values less than 0.05 were considered statistically significant.Results:There was a statistically significant difference in average lateral plateau PTS between standard short knee lateral and longstanding lateral radiographs (11.0 degrees versus 12.2 degrees, P =0.031). More importantly, 66.6% of the absolute measurements differed by at least 3 degrees, with variability as high as 7 degrees in our series as shown in Figures 1 and 2. 20/35 patients (57.1%) also had varus or valgus deformity > 2 degrees. Twelve patients underwent posterior slope correction as part of their revision ACL reconstruction. 8/12 of those patients (66.7%) had varus/valgus deformity > 2 degrees, and 41.7% (5/12) of patients required biplanar proximal tibial osteotomy correction to adequately address their multiplanar deformity.Conclusions:Long segment radiographs more completely evaluate the complex deformities of posterior tibial slope associated with failed ACL reconstruction, with less variability than standard short knee radiographs. In our series, a high percentage of patients needed biplanar correction, and we recommend obtaining long segment anteroposterior and lateral radiographs as essential imaging in these patients.

The effect of physical therapy and exercise on pain and functional capacity according to the radiological grade of knee osteoarthritis.

Physical therapy and exercise programs are frequently used in the treatment of knee osteoarthritis (OA). However, it is not known at what stage of knee OA it is more effective. The purpose of this work was to determine the relationship between the effectiveness of the physical therapy and exercise programs and the radiological findings presence/grade of knee OA. Overall, 92 patients (65F, 27M) with knee OA were enrolled in the retrospective study. Standard knee radiographs were graded according to Kellgren-Lawrence. Pain and functional status were evaluated using a visual analog scale (VAS) and the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) at baseline, at the end of the physical therapy program (first month), and at third-month control visits. The demographic characteristics and VAS/WOMAC scores of the subjects were obtained from patient files. We analyzed 131 knees of 92 patients with knee OA (65F, 27M, mean age 53.02 ± 11.13 years). The mean total VAS and WOMAC scores on the first and third months were significantly lower than the initial values (all p< 0.001). The mean VAS scores on the first and third months were significantly lower than the initial values in the group without radiological damage, but WOMAC scores were similar between the evaluations (p= 0.009, p 50 = 0.003, respectively). The mean VAS and WOMAC scores on the first and third months were significantly lower than the initial values in the grade 1 according to the Kellgren-Lawrence radiological grades (all p< 0.001). According to the results of our study, physical therapy and exercise was effective on pain in all patients with knee OA, but only effective on knee functional capacity in the group with radiological findings, and especially more effective in patients with Kellgren-Lawrence grade 1.

High Incidence of Intra-articular Injuries With Segond Fractures of the Tibia in the Pediatric and Adolescent Population.

Segond fractures (avulsion fractures of the proximal lateral tibia) are highly associated with anterior cruciate ligament (ACL) tears in adult patients. This large case series of pediatric Segond fractures describes the associated intra-articular knee injuries to determine if these fractures have a high incidence of ACL tears or its equivalent injury in young patients. Institutional review board approved retrospective study at a tertiary children's hospital of patients under 19 years who were diagnosed with a Segond fracture between 2009 and 2019 was conducted. Demographics, clinical data, imaging features, associated injuries, and treatment information were collected. Fifty-three patients (44 males and 9 females) with median age 15.4 (11.8 to 19) years with Segond fractures of the proximal tibia on radiographic imaging were included. Diagnosis of associated injuries was established based on clinical examination, radiology report, and arthroscopic findings. Median Segond fracture size was 2.0×9.0 mm measured on standard anteroposterior knee radiographs. Magnetic resonance imaging (MRI) was obtained in 49/53 (92.5%) patients. Associated injuries included ACL tears (39 patients, 73.6%), tibial spine fractures (9, 17.0%), and other injuries (5, 9.4%). 37/53 (69.8%) patients had meniscal injury. Three (5.7%) patients sustained multiligament injuries. All associated injuries were confirmed by either MRI/computerized tomography or direct operative examination. Among Segond fractures found with ACL tears, 12 (30.8%) were contact injuries, 30 (76.9%) were sports injuries. In associated tibial spine fractures, 7 (78%) injuries were contact in nature and were sports related. There was a statistically significant difference (P=0.013) in age, patients with tibial spine fractures (median 13.6 y) being younger than those with ACL tears (median 15.4 y). 12/53 (22.6%) had associated articular cartilaginous injuries, 3 of which were treated surgically. Overall, 81.1% of patients were treated operatively for associated intra-articular injuries. This large case series of Pediatric Segond fractures suggests a high association with intra-articular injuries, specifically, ACL tears and its equivalent injury, that is, tibial spine fractures, the later more common in the younger patient population. An MRI is recommended in patients with a Segond fracture for characterizing the exact intra-articular injury to help plan the appropriate management. Level IV-prognostic.

The Prevalence of Knee Symptoms, Radiographic, and Symptomatic Osteoarthritis at Four Time Points: The Johnston County Osteoarthritis Project, 1999-2018.

ObjectiveTo describe point prevalence of knee symptoms, radiographic knee osteoarthritis (rKOA), severe rKOA, and symptomatic rKOA at four time points in the longitudinal, population‐based Johnston County Osteoarthritis Project (JoCo OA).MethodsData were from 2573 JoCo OA participants with up to 18 years of follow‐up (1999‐2018) and standardized fixed‐flexion knee radiographs read by a single, reliable expert musculoskeletal radiologist. The four outcomes were 1) self‐reported knee symptoms, defined by “On most days, do you have pain, aching, or stiffness in your right/left knee?”; 2) rKOA, defined as a Kellgren‐Lawrence grade (KLG) of 2 to 4); 3) severe rKOA, defined as a KLG of 3 or 4; and 4) symptomatic rKOA, defined as both symptoms and rKOA in the same joint. Weighted prevalence estimates and 95% confidence intervals (CIs) were generated overall and by age group, sex, race, and body mass index (BMI).ResultsMost recently (2017‐2018, T4), the overall prevalence (percentage) of knee symptoms, rKOA, severe rKOA, and symptomatic rKOA was 41% (95% CI: 35‐47%), 61% (95% CI: 56‐67%), 35% (95% CI: 30‐40%), and 30% (95% CI: 24‐35%), respectively. From time point T1 to T4, prevalence increased for rKOA, severe rKOA, and symptomatic rKOA but not for knee symptoms. The prevalence of both severe rKOA (17‐39%) and symptomatic rKOA (23‐30%) was consistently higher among women. The prevalence of all outcomes was higher among those with higher BMI and among Black participants at all time points, particularly rKOA (35‐69%) and severe rKOA (22‐46%).ConclusionThese updated estimates demonstrate a large and increasing burden of knee OA, particularly among women and Black individuals.

ARE SEGOND FRACTURES OF THE TIBIA PATHOGNOMONIC FOR ACL TEARS IN THE PEDIATRIC AND ADOLESCENT POPULATION?

Background:Segond fractures (avulsion fractures of the proximal lateral tibia) are considered to be pathognomonic for anterior cruciate ligament (ACL) tears in adult patients.Purpose:To describe the largest case series of pediatric Segond fractures and associated intra-articular injuries of the knee to determine if these fractures are pathognomonic for ACL tears in young patients.Methods:IRB-approved retrospective study of patients under 20 years who presented with Segond fracture to a tertiary children’s hospital between 2009-2019. Demographics, clinical data, imaging features, associated injuries, and treatment information were collected.Results:55 patients (46 males, 9 females) with mean age 15.2 years (11.8-19.1) with Segond fractures of the proximal tibia on radiology imaging were identified (Fig.1.2). Diagnosis of associated injuries was established based on clinical examination, radiology report and findings during arthroscopy. Average Segond fracture size was 2.7 x 9.5mm as measured on standard knee radiographs. Magnetic resonance imaging (MRI) was obtained in 49/55(89%) patients. Associated injuries included anterior cruciate ligament (ACL) tears (39 patients, 70.9%), tibial eminence fractures (9, 16.4%), and all other injuries (7, 12.7%) (Table 1.1). Among Segond fractures found with ACL tears, 12 (30.8%) were contact injuries, 30 (76.9%) were sports injuries. In associated tibial spine fractures, 7 (78%) injuries were contact in nature and were sports related. When age was compared between the patient group with ACL tears (mean 15.7 years) to the ones with tibial spine fractures ( mean 13.9 years), there was a statistically significant difference(p=0.007). 12/55 (21.8%) had associated articular cartilaginous injuries, 3 of which required surgical intervention. 37/55 (67.3%) patients had meniscal injury. 3 (5.5%) patients suffered multi-ligament injuries. Overall, 87.2% of the patients required surgical management for associated intra-articular injuries of the knee.Conclusion:The Segond (tibial avulsion) fracture is associated with intra-articular injuries the pediatric population, most commonly ACL tears and meniscus tears. However, the largest case series in the pediatric population suggests that they are not pathognomonic for ACL tears as a notable proportion of patients, especially the ones who are younger in age, have tibial eminence fractures or no ACL tears.Figure 1.2.Antero-posterior knee radiograph showing Segond avulsion fracture of the proximal lateral tibia

An accurate method for locating the joint line during revision total knee arthroplasty: A radiologic study in the Chinese population

BackgroundThe systems for precisely locating the joint line during primary and revision total knee arthroplasty are still controversial, and they should be better evaluated in the Chinese population. MethodsA total of 451 standard anteroposterior knee radiographs from 451 healthy Chinese people (283 males and 168 females, the average age of 33.26 years, range 20–50 years) were included to measure the femoral width (FW) and the distances from the adductor tubercle (AT), the medial epicondyle (ME), the lateral epicondyle (LE), and the fibular head (FH) to the joint line (JL). Correlation between FW and distances from landmarks to the joint line was evaluated using Pearson correlation coefficient, and the ratios of ATJL, MEJL, LEJL, FHJL to FW were calculated. ResultsThe average distances from the AT, the ME, the LE, the FH to the JL were 49.4 ± 5.0 mm, 28.3 ± 3.1 mm, 26.9 ± 2.9 mm, 20.0 ± 4.0 mm, respectively. An excellent linear correlation was found between FW and the distance from AT to the joint line (R = 0.836, R2 = 0.698); it was more reliable than the LE (R = 0.686, R2 = 0.471) and the ME (R = 0.672, R2 = 0.452). The average ratios of ATJL/FW, MEJL/FW, LEJL/FW were 0.553, 0.317, and 0.302, respectively. There were significant differences between our results and the studies based on the Western people. ConclusionThe AT can be used as a reliable landmark to locate the JL precisely by the formula (ATJL = 0.548 × FW in males; ATJL = 0.562 × FW in females) in the Chinese population. The LE and ME can be the second choices. Moreover, it may be better to use ratios from the research based on the same race.

Posterior Tibial Slope Measurements Using the Anatomic Axis Are Significantly Increased Compared With Those That Use the Mechanical Axis

To compare posterior tibial slope (PTS) measurements from standard lateral knee radiographs with measurements from full-length lateral tibia radiographs. We performed a multicenter, prospective study. Lateral knee and full-length lateral tibia radiographs were obtained for each patient, and PTS was measured. Slope measurements were obtained by measuring the angle between an average of the medial and lateral tibial plateaus and a representative tibial diaphysis line. The proximal anatomic axis was measured on lateral knee radiographs, and both the mechanical axis and anatomic axis were measured on full-length lateral tibia radiographs. The mechanical axis was defined as the center of the plateau to the center of the plafond, and the anatomic axis was defined as the center of the tibial diaphysis. The minimal clinically significant difference was defined a priori as 2° of PTS or greater. A total of 140 patients met the inclusion criteria. The average PTS using the proximal anatomic axis was 11.6° ± 3.2° on lateral knee radiographs; the PTS measured on full-length lateral tibia radiographs was 9.5° ± 3.4° using the mechanical axis and 11.8° ± 3.1° using the anatomic axis. There was a significant difference between the measurements with the mechanical axis and both anatomic axis measurements (P < .01) but no significant difference between the 2 anatomic axis measurement techniques (P=.574). In total, 55% of patients (n= 77) had a 2° or greater difference between the proximal anatomic axis and mechanical axis PTS measurement techniques. There was no significant difference between PTS measurements that used the proximal anatomic axis from lateral knee radiographs and those that used the anatomic axis from full-length lateral tibia radiographs. Thus, lateral knee radiographs are adequate to accurately obtain tibial slope measurements. However, there was a significant difference between PTS measurements that used the anatomic axis and those that used the mechanical axis of the tibia. It is recommended that future studies report tibial slope based upon measurements that utilize the anatomic axis in order to ensure that subsequent conclusions are comparable, independent of the radiographic view.

The combination of an inflammatory peripheral blood gene expression and imaging biomarkers enhance prediction of radiographic progression in knee osteoarthritis

ObjectivePredictive biomarkers of progression in knee osteoarthritis are sought to enable clinical trials of structure-modifying drugs. A peripheral blood leukocyte (PBL) inflammatory gene signature, MRI-based bone marrow lesions (BML) and meniscus extrusion scores, meniscal lesions, and osteophytes on X-ray each have been shown separately to predict radiographic joint space narrowing (JSN) in subjects with symptomatic knee osteoarthritis (SKOA). In these studies, we determined whether the combination of the PBL inflammatory gene expression and these imaging findings at baseline enhanced the prognostic value of either alone.MethodsPBL inflammatory gene expression (increased mRNA for IL-1β, TNFα, and COX-2), routine radiographs, and 3T knee MRI were assessed in two independent populations with SKOA: an NYU cohort and the Osteoarthritis Initiative (OAI). At baseline and 24 months, subjects underwent standardized fixed-flexion knee radiographs and knee MRI. Medial JSN (mJSN) was determined as the change in medial JSW. Progressors were defined by an mJSN cut-point (≥ 0.5 mm/24 months). Models were evaluated by odds ratios (OR) and area under the receiver operating characteristic curve (AUC).ResultsWe validated our prior finding in these two independent (NYU and OAI) cohorts, individually and combined, that an inflammatory PBL inflammatory gene expression predicted radiographic progression of SKOA after adjustment for age, sex, and BMI. Similarly, the presence of baseline BML and meniscal lesions by MRI or semiquantitative osteophyte score on X-ray each predicted radiographic medial JSN at 24 months. The combination of the PBL inflammatory gene expression and medial BML increased the AUC from 0.66 (p = 0.004) to 0.75 (p < 0.0001) and the odds ratio from 6.31 to 19.10 (p < 0.0001) in the combined cohort of 473 subjects. The addition of osteophyte score to BML and PBL inflammatory gene expression further increased the predictive value of any single biomarker. A causal analysis demonstrated that the PBL inflammatory gene expression and BML independently influenced mJSN.ConclusionThe use of the PBL inflammatory gene expression together with imaging biomarkers as combinatorial predictive biomarkers, markedly enhances the identification of radiographic progressors. The identification of the SKOA population at risk for progression will help in the future design of disease-modifying OA drug trials and personalized medicine strategies.

Non-weightbearing imaging and standard knee radiographs are inferior to formal alignment radiographs for calculating coronal alignment of the knee

IntroductionRealignment knee osteotomy relies on accurate preoperative assessment of coronal alignment. Weightbearing (WB) ‘long-leg’ (LL) radiographs are the accepted gold-standard investigation, though in practice standard knee radiographs (short leg; SL) and non-weightbearing (NWB) cross-sectional imaging such as computed tomography (CT) scanograms have been used. We compare the accuracy of SL and NWB radiographs to formal LL alignment radiographs. MethodsA prospectively maintained osteotomy database was reviewed to identify the study population. All patients underwent standardised weightbearing long-leg alignment radiographs. The series was screened consecutively until 30 patients who also underwent WB SL radiographs (‘WB cohort’), and 30 with NWB SL (‘NWB cohort’) radiographs, were identified. Anatomic tibiofemoral angle was calculated by independent reviewers using a validated technique from both radiographs and contrasted. Results60 patients were identified as outlined in the study protocol. There were no differences in baseline demographics. Coronal alignment calculated from SL and LL radiographs differed significantly (median difference 2.1°, p < 0.001). Alignment values from weightbearing SL radiographs demonstrated markedly greater agreement with LL values than those from NWB radiographs (intraclass correlation coefficient 0.878 vs 0.657), with the NWB cohort also exhibiting greater outlier and extreme outlier incidence. ConclusionOur data adds to the growing evidence that SL radiographs are inadequate in the interpretation of knee alignment. In addition, we demonstrate that NWB radiographs (and by extension other NWB modalities such CT scanograms) demonstrate poorer agreement to gold-standard than WB methods. Coronal alignment of the knee cannot be reliably measured from non-weightbearing imaging modalities. Implications for practiceThough potentially useful as an adjunct, non-weightbearing cross-sectional imaging and standard knee radiographs should not be used as a proxy for formal weightbearing long-leg radiographs in osteotomy planning.

Predicting the mechanical hip–knee–ankle angle accurately from standard knee radiographs: a cross-validation experiment in 100 patients

Background and purpose — Being able to predict the hip–knee–ankle angle (HKAA) from standard knee radiographs allows studies on malalignment in cohorts lacking full-limb radiography. We aimed to develop an automated image analysis pipeline to measure the femoro-tibial angle (FTA) from standard knee radiographs and test various FTA definitions to predict the HKAA. Patients and methods — We included 110 pairs of standard knee and full-limb radiographs. Automatic search algorithms found anatomic landmarks on standard knee radiographs. Based on these landmarks, the FTA was automatically calculated according to 9 different definitions (6 described in the literature and 3 newly developed). Pearson and intra-class correlation coefficient [ICC]) were determined between the FTA and HKAA as measured on full-limb radiographs. Subsequently, the top 4 FTA definitions were used to predict the HKAA in a 5-fold cross-validation setting. Results — Across all pairs of images, the Pearson correlations between FTA and HKAA ranged between 0.83 and 0.90. The ICC values from 0.83 to 0.90. In the cross-validation experiments to predict the HKAA, these values decreased only minimally. The mean absolute error for the best method to predict the HKAA from standard knee radiographs was 1.8° (SD 1.3). Interpretation — We showed that the HKAA can be automatically predicted from standard knee radiographs with fair accuracy and high correlation compared with the true HKAA. Therefore, this method enables research of the relationship between malalignment and knee pathology in large (epidemiological) studies lacking full-limb radiography.

Langenskiöld Classification for Blount Disease: Is It Reliable?

Backgrounds:Blount disease (BD) is a developmental disease which medial part of the proximal tibial physis resulting genu varum. Plain radiographs are necessary for diagnosis. For this purpose, Langenskiöld classification is used. There are not enough data about Langenskiöld classification's reliability in the English literature. The purpose of this study is to evaluate the intra- and inter-reliability of Langenskiöld classification in BD.Materials and Methods:Thirty seven patients with BD were included in this cross-sectional study. Two separate presentations including clinical findings and standard knee radiographs were evaluated by three different groups (residents, surgeons, and pediatric orthopedic surgeons) and were sent to the observers every other month by hiding patients’ personal information. Intraobserver and interobserver reliabilities in these three groups were examined. Intraclass correlation coefficient (ICC) tests were used for this purpose.Results:Intraobserver reliability (ICC) was similar (excellent) in three groups (0.822, 0.804, and 0.763). Interobserver reliability among three groups was meanly excellent.Conclusion:Agreement to Langenskiöld classifications found excellent for three groups. Surgical experience did not change intraobserver and interobserver reliability in Langenskiöld classification.

A whole leg radiograph is not necessary for postoperative determination of the mechanical leg axis after total knee arthroplasty.

Anteroposterior (AP) whole leg radiographs (WLR) in the standing position for assessment of the mechanical leg axis are generally performed preoperatively for the planning of total knee replacement (TKR) and postoperatively to assess the leg axis. The objective of the present study was to investigate whether, if preoperative WLR are available, postoperative AP standard knee radiographs in the standing position are sufficient for calculating the mechanical leg axis. In the present prospective study, the mechanical and the anatomical leg axes were determined on the basis of WLR from 104 patients prior to implantation of a TKR and the difference was calculated. Twelve weeks postoperatively, standing long AP radiographs and WLR were prepared. In addition, the mechanical axis was calculated by adding the preoperative difference between the anatomical and mechanical axis to the anatomical axis from the postoperative AP radiographs. Accuracy, bias and level of agreement for calculated relative to measured mechanical alignment were determined. Mean accuracy of calculated mechanical alignment was 0.5° ± 0.4°, and mean bias was 0.0° ± 0.6° (p = 1.00). Bland-Altman analysis revealed a 95% upper and lower level of agreement of -1.3° and 1.3°, respectively. A preoperative WLR and a postoperative long AP knee standard radiograph are sufficient to determine the mechanical leg axis after TKR. If these are available, it is possible to do without WLR after TKR, particularly since they involve higher radiation exposure, are time-consuming, and are also prone to errors in the first postoperative weeks. II diagnostic study.

Methodical clinical measurement of knee deformity

The recognition of the pattern and severity of deformity in knee osteoarthritis has important implications in its management and prognosis. A number of methods can be used to assess and measure the coronal and sagittal knee alignment: clinical deformity measuring device like a goniometer, standard knee radiographs, hip-knee-ankle (HKA) radiographs, computer navigation systems, magnetic resonance scan, computerized tomographic scan or simply a surgeon’s subjective measurement. Each of these methods has advantages and disadvantages. The aim of this study was to compare three methods of measurement: clinical measurement with a goniometer; HKA radiographs and computer navigation. This study included 54 patients with arthritic knees, who underwent total knee replacement with computer navigation. The deformity in both coronal and sagittal planes was measured using the three methods and the results compared using Bland Altman limits of agreement. The clinical measurement differed greatly from radiographic and computer navigation measurements. According to Bland Altman limits of agreement clinical measurements could be up to 10° away from the radiographic or computer navigated measurements in coronal plane. In the sagittal plane the clinical measurements could be up to 12° away compared to computer navigation measurements. A combination of these measurements methods should be taken into account when assessing the deformity of a knee especially in relation to posture and weight bearing status. The methodical clinical measurement of knee deformity as described in this paper gives too wide a margin of error and should not be relied upon in isolation.

A Tomahawk Shape of the Femur Predicts Greater Rotatory Knee Laxity in Patients with Anterior Cruciate Ligament Ruptures

Aims and Objectives: Interindividual variations in knee laxity are poorly understood. Utilizing novel pivot shift arthrometers and patients in our ACL registry the magnitude of the pivot shift was found to vary between 0-14 mm of anterior translation in the lateral compartment. Increased tibial slope was found to influence the magnitude of the pivot shift, however, it is unclear if femur morphology might influence the magnitude of the pivot shift. Therefore, the purpose of this study was to determine the relationship between anterior translation of the lateral compartment during a quantitative pivot shift test and the posterior femoral offset, quantified as the “tomahawk ratio”, in patients with complete ACL rupture. It was hypothesized that the “tomahawk ratio” would correlate with increased anterior translation of the lateral compartment of the knee. Materials and Methods: Consecutive patients with no history of prior knee surgeries undergoing primary ACL reconstruction were analyzed. A standardized pivot shift test was performed preoperatively under anesthesia on both knees and quantified using tablet technology as previously described. Radiographic measurements were made using standard lateral knee radiographs. The long axis of the femur shaft was determined by a line through the center of two circles centered on the femoral shaft. The axis of the femoral condyle was determined by a line between the most posterior and most anterior points of the lateral condyle. The distance from the intersection of these lines to the posterior end of the condyle was divided by the total anteroposterior length of the condyle. This ratio was defined as “tomahawk ratio”. Pearson correlation coefficient was used to analyze correlations (p- value < 0.05). Results: Data sets were successfully obtained for 32 female and 25 male patients. The mean anterior translation of the lateral compartment during the pivot shift test was found to be 3.96 ±2.38 mm and 1.27±0.89 mm for the involved and uninvolved knees, respectively, with a mean side-to-side difference of 2.70±2.25 mm. The mean length of the lateral femoral condyle on x-ray was 68.36±5.31 mm, and the mean tomahawk ratio was 63.16±4.53%. There was a significant correlation between the tomahawk ratio and the absolute quantitative (r = 0.370 p < 0.05) and side-to-side differences in anterior translation of the lateral compartment (r =0.419 p < 0.05). Conclusion: The main finding from this study is that ACL-deficient patients with larger posterior femoral offsets quantified as the “tomahawk ratio” were found to have higher lateral translations of the knee during the pivot shift test. This suggests that variation in knee instability may be significantly affected by femoral bony morphology characterized by a larger posterior portion of the lateral condyle. This study may assist clinicians in evaluating ACL injuries and identifying patients at greater risk for increased rotational knee instability.

Radiographic markers for measuring tibial rotation based on CT-reconstructed radiographs: an accuracy and feasibility study.

Malreduction in the axial plane (malrotation) following tibial fracture surgery is often undiagnosed. A few clinical and radiographic methods have been proposed for measuring tibial rotation intraoperatively, yet have failed to match the accuracy of computed tomography (CT). The aim of this study was to develop radiographic tools for future intraoperative assessment of the tibial shaft rotation profile. The setting was a laboratory computerized analysis. Twenty lower limb CT scans were used to construct a three-dimensional (3D) model using AMIRA© software. A virtual 3D cylinder was implanted in the posterior condylar line and in the transmalleolar axis. The 3D models were used to simulate four standard knee and ankle plain radiographs. On each radiograph, four landmarks were depicted by two observers and their relation with the cylinder was measured and analyzed for accuracy and reproducibility. A cadaveric lower leg was implanted with two Kirschner wires. A CT scan was performed in addition to 2D fluoroscopy. The simulated radiographs and the fluoroscopy were compared for accuracy. Measurement of the landmarks showed reliability in most of the knee anteroposterior and ankle mortise radiographs (coefficients of variation <0.01 and =0.01) respectively. Cadaveric measurement of the landmarks using real fluoroscopy and simulated radiographs were similar. To date, no reliable and common methods have been reported for the evaluation of tibial axial rotation. We propose a model in which simple radiographic landmarks can be used to calculate a 3D coordinate system that accurately assesses the axial rotation angle of the tibial shaft.

Impact of surgeon’s hand and ocular dominance on right and left total knee arthroplasty alignment

Postoperative alignment is an important modifiable confounder that contributes to the longevity of total knee arthroplasty (TKA). Studies have shown that surgeon’s handedness can affect surgical performance; however, no studies have assessed the effect of surgeon’s hand or ocular dominance on TKA alignment. The purpose of this study was to evaluate the effect of surgeon’s hand and ocular dominance on coronal plane alignment in TKA.&#x0D; We retrospectively evaluated 138 patients who underwent sequential bilateral TKA by the same surgeon, using the Genesis II PS knee (Smith &amp; Nephew, Memphis, TN). We assessed postoperative alignment by measuring and comparing anatomical tibiofemoral angle (TFA) bilaterally on standard postoperative knee radiographs, as well as Knee Society function and pain scores to determine any functional differences. Lastly, we evaluated whether a crossed hand-ocular dominant surgeon had greater accuracy when performing a TKA on the side opposite their hand dominance compared to uncrossed hand-ocular dominant surgeons.&#x0D; All surgeons were right-hand dominant and there was a significantly larger anatomical TFA on left TKAs (mean [SD], 4.6° [2.8°]) compared to right TKAs (3.8° [2.5°]) (P = 0.003). There was no significant difference between right and left Knee Society function (P = 0.09) and pain scores (P = 0.86). When comparing left TKAs, surgeons with uncrossed hand-ocular dominance (4.5°) performed with equal accuracy compared to surgeons with crossed hand-ocular dominance (4.8°) (2-tailed test = 0.597), indicating no effect of ocular dominance.&#x0D; In summary, hand but not ocular dominance was shown to have significant postoperative alignment effects on TKA.