3D Bone Shape Research Articles

3D bone shape from CT-scans provides an objective measure of osteoarthritis severity: Data from the IMI-APPROACH study

Decisions regarding total knee arthroplasty are usually made using a patient's own assessment of pain and the structural disposition of the joint as seen on plain film radiographs. Pain severity can fluctuate, and radiographs can be misleading, with the apparent joint status affected by anatomical orientation. An important component of the surgical management of knee osteoarthritis (OA) is the timing of surgical intervention: knee arthroplasty performed too early in the course of the disease may increase the need for revision surgery.Femoral 3D bone shape (B-score) from MR images is an objective measure of OA severity and has been correlated with current and future risk of pain. We aimed to derive the B-score from CT images and compare it against the B-score derived from MR images.We used baseline and 24-month image data from the IMI-APPROACH 2-year prospective cohort study, comprising pairs of CT and MR images taken for each subject-timepoint. The femur was automatically segmented in both CT and MR modalities using an active appearance model, a machine-learning method, to measure the B-score. Linear regression was used to test for correlation between measures. Limits of agreement and bias were tested using Bland-Altman analysis.CT-MR pairs of the same knee were available from 424 participants (78 % women). B-scores from CT and MR were strongly correlated (CCC = 0.980) with negligible bias of 0.0106 (95 % CI: −0. 0281, +0.0493).The strong correlation and small B-score bias suggests that B-scores may be measured reliably using CT images. Since CT images are used in planning robot-assisted knee arthroplasty, with further study B-scores derived from CT surgical planning images could in principle provide a useful objective input to deciding the appropriateness, timing and type of knee arthroplasty.

Prognostic value of B-score for predicting joint replacement in the context of osteoarthritis phenotypes: Data from the osteoarthritis initiative

ObjectiveDeveloping new therapies for knee osteoarthritis (KOA) requires improved prediction of disease progression. This study evaluated the prognostic value of clinical clusters and machine-learning derived quantitative 3D bone shape B-score for predicting total and partial knee replacement (KR). DesignThis retrospective study used longitudinal data from the Osteoarthritis Initiative. A previous study used patients' clinical profiles to delineate phenotypic clusters. For these clusters, the distribution of B-scores was assessed (employing Tukey's method). The value of both cluster allocation and B-score for KR-prediction was then evaluated using multivariable Cox regression models and Kaplan-Meier curves for time-to-event analyses. The impact of using B-score vs. cluster was evaluated using a likelihood ratio test for the multivariable Cox model; global performances were assessed by concordance statistics (Harrell's C-index) and time dependent receiver operating characteristic (ROC) curves. ResultsB-score differed significantly for the individual clinical clusters (p ​< ​0.001). Overall, 9.4% of participants had a KR over 9 years, with a shorter time to event in clusters with high B-score at baseline. Those clusters were characterized clinically by a high rate of comorbidities and potential signs of inflammation. Both phenotype and B-score independently predicted KR, with better prediction if combined (P ​< ​0.001). B-score added predictive value in groups with less pain and radiographic severity but limited physical activity. ConclusionsB-scores correlated with phenotypes based on clinical patient profiles. B-score and phenotype independently predicted KR surgery, with higher predictive value if combined. This can be used for patient stratification in drug development and potentially risk prediction in clinical practice.

3-dimensional bone shape and knee osteoarthritis: What have we learned?

The concept that multiple joint tissues are involved in the osteoarthritis (OA) disease process is now widely accepted. There have been significant and important insights over the past two decades in the understanding of bone as a tissue undergoing pathological changes in OA. The specific bony changes of osteophyte growth and “bone attrition” associated with OA have been recognized for many years with several semi-quantitative radiographic and magnetic resonance imaging (MRI) grading systems designed to capture the magnitude of these changes. Over the past decade, there has been significant and important progress in the quantitative measurement of these changes. Manual methods for measuring bone area from 3D MR images have been improved with automation which offers both superior precision and a more responsive measurement that has been applied in several DMOAD randomized controlled trials. Measurement of true 3D bone shape, as opposed to simple geometric measures such as curvature and length, depends on automated methods of segmentation. In this field, important developments have taken place in the statistical parameterization of shape and the construction of OA vs non-OA shape metrics. Work has demonstrated that bone shape may provide an indication of OA status, may predict future OA onset, and is associated with clinical markers of OA such as pain, function and total joint replacement (TKR). Thus, bone shape may be a useful imaging biomarker for OA.

Using 3D MRI Bone Shape to Predict Pre-Osteoarthritis of the Knee 2 Years After Anterior Cruciate Ligament Reconstruction

Background: Anterior cruciate ligament (ACL) injury increases risks for osteoarthritis (OA), a poorly modifiable and disabling condition. Joint changes of potentially reversible pre-OA have been described just 2 years after ACL reconstruction (ACLR) when early bone shape changes have also been reported. Purpose: This study evaluates relationships between interlimb differences in tibiofemoral bone shape derived from statistical shape modeling (SSM) of magnetic resonance imaging (MRI) and participant factors on patient-reported outcomes 2 years after unilateral ACLR. Study Design: Cross-sectional study; Level of evidence, 3. Methods: SSM-derived tibiofemoral bone shape and subchondral bone area were assessed from bilateral knee MRI scans of 72 participants with unilateral ACLR (mean age, 34 ± 11 years; 32 women) and compared with a reference cohort of 398 older individuals without OA (mean age, 50 ± 3 years; 213 women). Multivariable logistic regression models examined relationships between participant and surgical factors with interlimb differences in bone shapes or subchondral bone areas. Relationships between patient-reported outcomes and the interlimb differences in bone shape and subchondral area were examined using similar models. Results: Bone shape scores and subchondral bone areas were greater (more OA-like) in ACLR knees than uninjured contralateral knees in every bone metric tested (P≤ .001). Interlimb differences in femur shape scores of participants with ACLR were 65% greater (P < .001) than those of the significantly older reference cohort. Taller height, medial meniscal tears, and decreasing age were associated with larger interlimb differences in shape scores and subchondral areas (P < .05). Bone–patellar tendon–bone (BPTB) autograft recipients demonstrated greater interlimb subchondral area differences compared with allograft recipients (P < .05). Interlimb differences for hamstring autograft recipients did not differ from those with BPTB or allograft. Greater interlimb differences in medial femur subchondral areas were associated with worse patient-reported Knee injury and Osteoarthritis Outcome Score Symptoms (R = 0.27; P = .040). Conclusion: Even in the absence of radiographic OA, just 2 years after unilateral ACLR patients showed greater bone shape scores and subchondral areas consistent with pre-OA in their ACLR knees. Furthermore, greater medial femur bone areas were weakly associated with worse symptoms. Patients who are younger, are taller, have meniscal tears, or have BPTB grafts may be at increased risk for bony asymmetries 2 years after ACLR.

Comparison of 3D quantitative osteoarthritis imaging biomarkers from paired CT and MR images: data from the IMI-APPROACH study

IntroductionMRI bone surface area and femoral bone shape (B-score) measures have been employed as quantitative endpoints in DMOAD clinical trials. Computerized Tomography (CT) imaging is more commonly used for 3D visualization of bony anatomy due to its high bone-soft tissue contrast. We aimed to compare CT and MRI assessments of 3D imaging biomarkers.MethodsWe used baseline and 24-month image data from the IMI-APPROACH 2-year prospective cohort study. Femur and tibia were automatically segmented using active appearance models, a machine-learning method, to measure 3D bone shape, area and 3D joint space width (3DJSW). Linear regression was used to test for correlation between measures. Limits of agreement and bias were tested using Bland-Altman analysis.ResultsCT-MR pairs of the same knee were available from 434 participants (78% female). B-scores from CT and MR were strongly correlated (CCC = 0.967) with minimal bias of 0.1 (SDD = 0.227). Area measures were also correlated but showed a consistent bias (MR smaller). 3DJSW showed different biases (MR larger) in both lateral and medial compartments.DiscussionThe strong correlation and small B-score bias suggests that B-score may be measured reliably using either modality. It is likely that the bone surface identified using MR and CT will be at slightly different positions within the bone/cartilage boundary. The negative bone area bias suggests the MR bone boundary is inside the CT boundary producing smaller areas for MR, consistent with the positive 3DJSW bias. The lateral-medial 3DJSW difference is possibly due to a difference in knee pose during acquisition (extended for CT, flexed for MR).Trial registrationNCT03883568

WBCT and its evolving role in OA research and clinical practice

ObjectiveAlthough radiography has traditionally been the most common means of imaging knee and ankle osteoarthritis (OA), the technology is limited in its abilities to accurately detect features of OA and provide accurate, sensitive, and responsive imaging biomarkers. More advanced modalities such as non-weight-bearing CT and MRI reveal additional details not well visualized on weight-bearing radiographs, such as 3D bone shape, subchondral cysts, and presence of meniscal extrusions. However, the clinical value of these imaging modalities is limited by the non-functional position during image acquisition. This mini-review examines the value added by WBCT and its evolving role in lower limb OA research and clinical practice. DesignNarrative mini-review. ResultsWeight-bearing computed tomography (WBCT) recently has been found to detect signs of OA that are commonly not as well visualized by other imaging modalities. Studies have shown that WBCT detects osteophytes, subchondral cysts and joint space narrowing more accurately than radiographs. The structural changes associated with assessment of functionally loaded knees and the 3D models provided by WBCT offer compelling insight into disease processes not easily discernable on other imaging modalities. Emerging evidence suggests that WBCT reveals meniscal extrusion not detected by MRI and that contrast enhancement—WBCT arthrography (WBCTa)— visualizes meniscal tears not seen on MRI. ConclusionsClinicians specializing in foot and ankle disorders have adopted WBCT as an imaging modality of choice and its value is becoming recognized for evaluation of other lower limb joints as well.

Effect of zoledronic acid with or without methylprednisolone on 3D bone area and bone shape in patients with symptomatic knee osteoarthritis: A post-hoc analysis of the ZAP2 trial

ObjectiveTo evaluate the effect of annual infusions of zoledronic acid (ZA) with or without a single injection of methylprednisolone, compared to placebo, on quantitative magnetic resonance imaging 3-D bone area and bone shape in participants with symptomatic knee osteoarthritis (OA). MethodsThis was a post-hoc analysis of the ZAP2 trial. Active appearance modelling was used to assess bone area (mm2) and femur bone shape (B-score) in 262 participants (mean 61.8 ± 8.0 years, 51% female) at baseline, 6, and 24 months. Radiographic joint space narrowing (JSN) was measured at baseline. An ‘OA shape’ was defined as a B-score of >1.96. ResultsAt baseline 65% of participants demonstrated an OA shape. Treatment with ZA plus methylprednisolone but not ZA alone, compared to placebo, was associated with significantly slower expansion in bone area at the medial femoral (-33.9 mm2, 95% confidence interval [CI] -61.8 to -6.0) and lateral femoral (-22.0 mm2, 95%CI -40.7 to -3.4) compartments over 24 months. B-score increased in all groups, with no significant between-group differences. There were significant interactions of JSN (grade 0 vs grade 1–2) and B-score (≤1.96 vs >1.96) with treatment effect on bone area (p < 0.05), such that ZA plus methylprednisolone slowed the expansion of medial and lateral femoral bone area over 24 months in participants with JSN grade 1–2 or a B-score of >1.96. ConclusionsZA plus methylprednisolone may retard expansion of bone area over 24 months, but ZA alone may not. Neither ZA with or without methylprednisolone slowed progression of bone shape over 6 or 24 months.

Evaluation of Subtalar Joint's Compensatory Function in Varus Ankle Osteoarthritis Using Globally Optimal Iterative Closest Points (Go-ICP).

Background:A previous study on 2-dimensional evaluation of the subtalar joint functioning in varus ankle osteoarthritis concluded that varus deformity was compensated for by the subtalar joint during early stages but not in the advanced stages. Although compensatory function is expected both along the axial and coronal planes, compensatory function in all 3 dimensions (3D) remains unevaluated. This study evaluated the 3D-compensatory function of a varus subtalar joint using Globally Optimal Iterative Closest Points (Go-ICP), a 3D-shape registration algorithm, after 3D-bone shape reconstruction using computed tomography.Methods:This study included 22 ankles: 4 stage 2 ankles, 5 stage 3a ankles, 6 stage 3b ankles, and 4 stage 4 ankles, categorized according to the Takakura-Tanaka classification. As the control group, 3 ankles without prior ankle injuries and disorders and 4 stage 2 ankles were included. One control ankle was used as a reference. Relative values compared with the reference ankle were evaluated in each group using Go-ICP. Each axis was set so that dorsiflexion, valgus, and abduction were positive on the X axis, Y axis, and Z axis, respectively.Results:Rotation angles of the talus (Rotation T) and calcaneus (Rotation C) on the Y axis in the control and stage 3b were −7.6, −28, −2.1, and −13 degrees, respectively, indicating significant differences. Value of Rotation T-Rotation C (Rotation T-C) represents compensatory function of the subtalar joint. In all ankles, there was a correlation between Rotation T and Rotation T-C on the Y axis and Z axis (P < .01, r = 0.84; P < .01, r = −0.84, respectively). There was a correlation between Rotation T values on the on Y and Z axes (P = .01, r = 0.53).Conclusion:In varus ankle osteoarthritis, the talus had varus deformity with adduction. Compensatory function in the coronal plane persisted, even in the advanced stages; however, it was not sufficiently maintained in stage 3b. Furthermore, compensatory function in the axial plane was relatively sustained.Level of Evidence:Level III, retrospective comparative study.

Statistical shape model of the talus bone morphology: A comparison between impinged and nonimpinged ankles.

Diagnosis of ankle impingement is performed primarily by clinical examination, whereas medical imaging is used for severity staging and treatment guidance. The association of impingement symptoms with regional three-dimensional (3D) bone shape variaties visible in medical images has not been systematically explored, nor do we know the type and magnitude of this relation. In this cross-sectional case-control study, we hypothesized that 3D talus bone shape could be used to quantitatively formulate the discriminating shape variations between ankles with impingement from ankles without impingement, and we aimed to characterize and quantify these variations. We used statistical shape modeling (SSM) methods to determine the most prevalent modes of shape variations that discriminate between the impinged and nonimpinged ankles. Results of the compactness and parallel analysis test on the statistical shape model identify 8 prominent shape modes of variations (MoVs) representing approximately 78% of the total 3D variations in the population of shapes, among which two modes captured discriminating features between impinged and nonimpinged ankles (p value of 0.023 and 0.042). Visual inspection confirms that these two shape modes, capturing abnormalities in the anterior and posterior parts of talus, represent the two main bony risk factors in anterior and posterior ankle impingement. In conclusion, in this research using SSM we have identified shape MoVs that were found to correlate significantly with bony ankle impingement. We also illustrated potential guidance from SSMs for surgical planning.

Estimating and abstracting the 3D structure of feline bones using neural networks on X-ray (2D) images

Computing 3D bone models using traditional Computed Tomography (CT) requires a high-radiation dose, cost and time. We present a fully automated, domain-agnostic method for estimating the 3D structure of a bone from a pair of 2D X-ray images. Our triplet loss-trained neural network extracts a 128-dimensional embedding of the 2D X-ray images. A classifier then finds the most closely matching 3D bone shape from a predefined set of shapes. Our predictions have an average root mean square (RMS) distance of 1.08 mm between the predicted and true shapes, making our approach more accurate than the average achieved by eight other examined 3D bone reconstruction approaches. Each embedding extracted from a 2D bone image is optimized to uniquely identify the 3D bone CT from which the 2D image originated and can serve as a kind of fingerprint of each bone; possible applications include faster, image content-based bone database searches for forensic purposes.

3D patella and femur bone shape modeling for patella instability patients

Purpose: Lateral patellar instability is a common knee problem that accounts for more than 10% of the musculoskeletal specialist office visits. It causes significant functional impairment to the young and active patient population. Dislocation and relocation of the patella loads cartilage traumatically, resulting in cartilage degeneration which can be consistently detected with MRI within 10 years from the initial instability episode. Moreover, patellar instability increases the risk of developing osteoarthritis by a factor of 8.

3D patella bone shape modeling after ACL injury and the association with cartilage health over 3-years after acl reconstruction

3D patella bone shape modeling after ACL injury and the association with cartilage health over 3-years after acl reconstruction

Marked and rapid change of bone shape in acutely ACL injured knees – an exploratory analysis of the Kanon trial

To investigate changes in knee 3D bone shape over the first 5 years after acute anterior cruciate ligament (ACL) injury in participants of the randomized controlled KANON-trial. Serial MR images over 5 years from 121 young (32 women, mean age 26.1 years) adults with an acute ACL tear in a previously un-injured knee were analyzed using statistical shape models for bone. A matched reference cohort of 176 individuals was selected from the Osteoarthritis Initiative (OAI). Primary endpoint was change in bone area of the medial femoral condyle; exploratory analyses compared results by treatment and examined other knee regions. Comparisons were made using repeated measures mixed model ANOVA with adjustment for age, sex and body mass index (BMI). Mean medial femur bone area increased 3.2% (78.0 [95% CI 70.2 to 86.4] mm2) over 5 years after ACL injury and most prominently in knees treated with ACL reconstruction (ACLR). A higher rate of increase occurred over the first 2years compared to the latter 3-years (66.2 [59.3 to 73.2] vs 17.6 [12.2 to 23.0] mm2) and was 6.7 times faster than in the reference cohort. The pattern and location of shape change in the extrapolated KANON data was very similar to that observed in another knee-osteoarthritis cohort. 3D shape modelling after acute ACL injury revealed rapid bone shape changes, already evident at 3 months. The bone-change pattern after ACL injury demonstrated flattening and bone growth on the outer margins of the condyles similar to that reported in established knee osteoarthritis.

The relationship between two different measures of osteoarthritis bone pathology, bone marrow lesions and 3D bone shape: data from the Osteoarthritis Initiative

SummaryObjectiveBone shape and bone marrow lesions (BMLs) represent different features of Magnetic resonance imaging (MRI)-detected subchondral pathology in osteoarthritis (OA). The aim of this study was to determine how these features are related and how they change in OA progression.Methods600 participants from the Osteoarthritis Initiative (OAI) FNIH Biomarkers Initiative were included, having Kellgren–Lawrence grade 1–3, at baseline and MRI data at baseline and 24 months. The associations between 3D quantitative bone shape vectors and presence of (MRI Osteoarthritis Knee Score) MOAKS semi-quantitative BMLs (total BML size ≥1) were analysed for femurs and tibias using linear regression. Responsiveness over 24 months was calculated for both features in four pre-defined progression groups and reported as standardised response means (SRMs). Multilevel models investigated the longitudinal relationship between change in BML size and change in bone shape.ResultsMean age was 61.5, 59% female and mean body mass index (BMI) 30.7. Correlation between baseline femur vector and BML was r = 0.28, P < 0.001. The presence of BMLs was associated with higher bone shape vector; coefficient (95% CI) 0.75 (0.54, 0.96) and 0.57 (0.38, 0.77) for femur and tibia respectively, both P < 0.001. After covariate adjustment, only the femur remained significant [coefficient 0.49, (95% CI 0.30, 0.68)]. Longitudinally bone vector demonstrated more responsiveness to change than BMLs (SRM 0.89 vs 0.13) while multilevel models revealed that increase in BML size was related to a more positive bone shape vector (representing worsening OA).ConclusionThere is a relationship between bone shape and BMLs, with prevalence of BMLs associated with increasing OA bone shape. Bone shape demonstrated greater responsiveness than semi-quantitative BMLs.

The relationship between two different measures of osteoarthritis bone pathology, bone marrow lesions and 3D bone shape: data from the osteoarthritis initiative

Purpose: Magnetic resonance imaging (MRI) has provided great insights into the development of OA, and helped highlight the importance of subchondral bone pathology. Bone shape and bone marrow lesions (BMLs) represent different features of MRI-detected subchondral pathology in osteoarthritis (OA) and while BMLs are well studied the relationship between these two remains poorly understood. It is important to understand if they represent a single construct or different parts of the OA process, and to further explore their use as imaging biomarkers. The aim of this study was to determine how these features are related and how they change in OA progression. Methods: 600 participants from the FNIH Biomarkers Initiative of the OAI were included, having Kellgren–Lawrence (KL) 1, 2 or 3 at baseline and MRI data at baseline and 24 months. MRI images obtained from the OAI were scored for BMLs using the semi-quantitative MOAKS system that scores 3 features using an ordinal scale for size, number of BMLs and percentage of lesion that is a BML as opposed to a cyst. Quantitative 3D bone shape data was provided by Imorphics (Manchester, UK) using active appearance models (AAMs) applied separately for femur and tibia from 3T DESS-we images. The shape vector for each bone was calculated by taking the principal components of the mean non-OA shape and the mean OA shape and the vector was normalised by setting the mean OA shape to +1 and mean non-OA shape as −1, with each unit increase of 1 representing 1 standard deviation (SD) calculated in non-OA knees. Four BML scores were computed: “BML total size”, “BML total number”, “BML total sub regions” and BML maximum size”. At baseline the correlation between the BML scores and bone shape measures were assessed using Spearman`s correlation coefficients. The association between 3D quantitative bone shape vectors and BMLs at baseline was analysed using linear regression. Presence of a BML was defined as BML total size ≥ 1. Responsiveness was calculated for both features in 4 pre-defined progression groups and reported as standardised response means (SRMs).Due to nesting of repeated measurements within individuals, multilevel linear modelling was used to assess the longitudinal relationship between change in BML size and change in bone shape vector. Results: Mean age was 61.5, 59% were female and mean BMI was 30.7. Correlation between baseline femur shape vector and femur BML total size was r = 0.28, P < 0.001 and similar for the tibia. Linear models revealed an association between presence of a femur BML at baseline and baseline 3D femur vector in both univariable and multivariable models (adjusted coefficient 0.49, 95% CI 0.30, 0.68) indicating a more positive femur vector (indicative of “increased OA”) in individuals with BMLs at baseline, with a difference equivalent to 0.5 × SD of non-OA knees. Longitudinally bone shape demonstrated more responsiveness to change than all BML measures (SRM 0.89 vs 0.13) for femur bone shape vector vs BML total size respectively (Table 1). Univariable growth models revealed that bone shape vector tended to be more positive over time (indicating worsening) while BML total size reduced over time. Multilevel models also showed that an increase in BML size was related to a more positive bone shape vector (representing worsening OA). Conclusions: There is a relationship between bone shape and BMLs, with increasing OA bone shape vector associated with higher prevalence of BMLs. Bone shape vector demonstrated greater responsiveness than semi-quantitative BMLs over time periods typical of a clinical trial.Table 1Responsiveness of bone shape and BML measures over 24 monthsRadiographic and pain progression N = 194Radiographic progression only N = 103Pain progression only N = 103No progression N = 2002 year responsiveness, SRM (95%CI)Bone shapeFemur0.89 (0.72,1.02)1.02 (0.85,1.20)0.46 (0.31,0.61)0.61 (0.49,0.72)Tibia0.84 (0.70,0.97)0.76 (0.56,0.96)0.26 (0.07,0.43)0.47 (0.33,0.69)BMLsFemur BML total size−0.13 (−0.26,0.02)−0.15 (−0.35,0.07)−0.31 (−0.51,−0.13)−0.24 (−0.37,0.13)Femur BML total number0.38 (0.26,0.50)0.20 (−0.02,0.41)0.17 (−0.04,0.35)0.27 (0.14,0.38)Tibia BML total size0.11 (−0.02,0.26)0.14 (−0.04,0.31)−0.04 (−0.23,0.15)−0.01(−0.16,0.11)Tibia BML total number0.37 (0.24,0.51)0.31 (0.12,0.51)0.19 (0.00,0.33)0.16 (0.02,0.29)Femur BML maximum size−0.05 (−0.19,−0.09)−0.01 (−0.19,0.21)−0.20 (−0.38,0.01)−0.11 (−0.25,0.02)BML total sub regions−0.02 (−0.15,0.13)−0.03 (−0.23,0.15)−0.13 (−0.32,0.07)−0.06 (−0.20,0.08) Open table in a new tab

Study of the interactions between proximal femur 3d bone shape, cartilage health, and biomechanics in patients with hip Osteoarthritis.

In this study quantitative MRI and gait analysis were used to investigate the relationships between proximal femur 3D bone shape, cartilage morphology, cartilage biochemical composition, and joint biomechanics in subject with hip Osteoarthritis (OA). Eighty subjects underwent unilateral hip MR-imaging: T1ρ and T2 relaxation times were extracted through voxel based relaxometry and bone shape was assessed with 3D MRI-based statistical shape modeling. In addition, 3D gait analysis was performed in seventy-six of the studied subjects. Associations between shape, cartilage lesion presence, severity, and cartilage T1ρ and T2 were analyzed with linear regression and statistical parametric mapping. An ad hoc analysis was performed to investigate biomechanics and shape associations. Our results showed that subjects with a higher neck shaft angle in the coronal plane (higher mode 1, coxa valga), thicker femoral neck and a less spherical femoral head (higher mode 5, pistol grip) exhibited more severe acetabular and femoral cartilage abnormalities, showing different interactions with demographics factors. Subjects with coxa valga also demonstrated a prolongation of T1ρ and T2. Subjects with pistol grip deformity exhibited reduced hip internal rotation angles and subjects with coxa valga exhibited higher peak hip adduction moment and moment impulse. The results of this study establish a clear relationship between 3D proximal femur shape variations and markers of hip joint degeneration-morphological, compositional, well as insight on the possible interactions with demographics and biomechanics, suggesting that 3D MRI-based bone shape maybe a promising biomarker of early hip joint degeneration. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:330-341, 2018.

3D Knee Bone Shape Predisposes to ACL Rupture: Data from the Osteoarthritis Initiative and the Kanon Study

3D Knee Bone Shape Predisposes to ACL Rupture: Data from the Osteoarthritis Initiative and the Kanon Study

The relationship between three-dimensional knee MRI bone shape and total knee replacement-a case control study: data from the Osteoarthritis Initiative.

Objective. There is growing understanding of the importance of bone in OA. Our aim was to determine the relationship between 3D MRI bone shape and total knee replacement (TKR).Methods. A nested case-control study within the Osteoarthritis Initiative cohort identified case knees with confirmed TKR for OA and controls that were matched using propensity scores. Active appearance modelling quantification of the bone shape of all knee bones identified vectors between knees having or not having OA. Vectors were scaled such that −1 and +1 represented the mean non-OA and mean OA shapes.Results. Compared to controls (n = 310), TKR cases (n = 310) had a more positive mean baseline 3D bone shape vector, indicating more advanced structural OA, for the femur [mean 0.98 vs −0.11; difference (95% CI) 1.10 (0.88, 1.31)], tibia [mean 0.86 vs −0.07; difference (95% CI) 0.94 (0.72, 1.16)] and patella [mean 0.95 vs 0.03; difference (95% CI) 0.92 (0.65, 1.20)]. Odds ratios (95% CI) for TKR per normalized unit of 3D bone shape vector for the femur, tibia and patella were: 1.85 (1.59, 2.16), 1.64 (1.42, 1.89) and 1.36 (1.22, 1.50), respectively, all P < 0.001. After including Kellgren–Lawrence grade in a multivariable analysis, only the femur 3D shape vector remained significantly associated with TKR [odds ratio 1.24 (1.02, 1.51)].Conclusion. 3D bone shape was associated with the endpoint of this study, TKR, with femoral shape being most associated. This study contributes to the validation of quantitative MRI bone biomarkers for OA structure-modification trials.

The relationship between knee symptoms and 3D MRI knee bone shape: Data from the Osteoarthritis Initiative

The relationship between knee symptoms and 3D MRI knee bone shape: Data from the Osteoarthritis Initiative

3D MRI-based knee shape and its association with incident osteoarthritis and sex differences (data from OAI dataset)

Purpose: This study utilizes a 3D magnetic resonance imaging (MRI) based statistical shape modeling (SSM) method to analyze differences in bone shape of the knee joint that may be associated with incident OA. The purpose of this study is two-fold: (i) to investigate differences in knee bone shape between incident osteoarthritis (OA) cases and controls; and (ii) to investigate sex differences in bone shape. Methods: 20 subjects (10 women) without radiographic signs of OA at baseline (KL=0), but with incident OA at 4 years follow up (KL=2) (cases) were identified randomly from the Osteoarthritis Initiative dataset and matched for age, BMI, and gender in a ratio of 1:1 to 20 controls (10 women) who did not show radiographic evidence of OA over the examination period (KL=0 at baseline and at 4 years). All 40 subjects underwent right knee 3.0 Tesla MR scans. Baseline sagittal 3D double-echo steady-state (DESS) with water excitation images (field of view = 140 mm, number of slices = 160, slice thickness = 0.7 mm, TE/TR 4.7/16.3 mm, TR pixel spacing (0.37 mm, 0.46 mm)) were processed using an in-house Matlab program that segmented the femur and tibia semi-automatically from a collection of plotted markers. A vertex-to-vertex correspondence of the reference knee was mapped onto each candidate surface using a fully automatic landmark-matching algorithm, invariant of size and rotation. Principal Component Analysis (PCA) of the covariance matrix for the landmarks provided relevant shape information. Each case was described by 20 tibia and femur modes (F1-F20, T1-T20) that represent aspects of the 3D bone shape. The mean shape and±5 standard deviations of each mode are presented (Figure 1). Results: Cases and controls had similar mean age and BMI (cases: age = 58.1±6.6 years, BMI = 26.3±2.9 kg/m2, controls: age = 58.1±7.0 years, BMI = 26.4±2.9 kg/m2, p > 0.05). With respect to femoral modes, cases had significant differences in modes F4 (cases: −97.74±178.08, controls: 92.86±176.39 p = 0.002) and F8 (cases: −44.06±107.89, controls: 41.86±124.02, p = 0.027). Negative values in F4 indicated an increase in the length and width of the lateral condyle of the femur relative to the medial condyle, whereas negative F8 values suggested a deeper trochlear groove. For the tibia, differences were less pronounced. In mode T3, cases were borderline different from control knees (cases: −121.92±283.35, controls: 136.26±471.43, p = 0.052). In T4, cases also showed a trend towards significance (cases: −100.91±337.68, controls: 112.79±297.13, p = 0.053). Negative values represent elevation of the medial tibial plateau in T3, and a flatter posterior tibial slope in T4. With respect to our secondary aim, the analysis of bone shape between sexes with knee OA showed that femoral mode F7 was −40.1±134.5 for men, while it was 57.7±103.8 (p = 0.019) for women. Similarly, mean F13 was significantly different in men (−26.15±86.5) versus women (38.1±93.8, p = 0.0032). Negative values in F7 indicated a narrowed intercondylar notch and shallow trochlear groove, whereas positive values showed widened condyles and a deeper trochlear groove. Negative F13 values yielded both a deeper intercondylar notch and trochlear groove. Tibial mode T3 was also significantly different between men (99.7±435.8) and women (−176.4±256.2, p = 0.045). Shape description for T3 is as above. Conclusions: This study suggests that shape differences including a wider and longer lateral condyle (F4), deeper trochlear groove (F8), elevated medial tibial plateau (T3), and flatter posterior slope (T4), may be associated with incident OA. Also, tibial plateau elevation (T3), intercondylar notch width (F7/F13), and trochlear depth (F7/F13) are associated with sex differences. Future analyses of shape modes may allow for their use as target biomarkers in OA.