Dataset Information

An Anatomic Study on Whether the Patella is Centered in an Ideal Anteroposterior Radiograph of the Knee.

ABSTRACT:

Background

Currently, an anteroposterior radiograph of the knee is judged based on a centered position of the patella between the femoral condyles. We are not aware of any anatomic literature supporting this recommendation.

Questions/purposes

Orthogonal images are required for accurate assessment of knee deformity. Although an image with the patella centered at the distal femur is generally accepted as a true anteroposterior (AP) radiograph of the knee, there is minimal anatomic data to support that this view is orthogonal to a true lateral view of the knee where the condyles are overlapped. We designed an anatomical study to test the relationship between these two radiographic views.

Methods

We studied 428 well-preserved cadaveric skeletons ranging from 40 to 79 years of age at death. Centering of the patella was calculated based on distal femoral and patellar widths. Multiple regression analysis was then performed to determine the relationship between patellar centering and age, gender, ethnicity, mechanical lateral distal femoral angle (mLDFA), medial proximal tibial angle (MPTA), femoral anteversion, and contralateral centering.

Results

Average patellar centering was 0.13?±?0.04, indicating that the average patella was laterally positioned in the distal femur. Only mLDFA and contralateral centering showed statistically significant independent correlations with patellar centering with modest standardized beta coefficients of 0.10 and 0.23, respectively.

Conclusions

In the average specimen, the patella is laterally deviated by 13% of the condylar width. Clinicians should be aware that a lateral view with the femoral condyles overlapped is not always orthogonal to a patella-centered AP view when planning and implementing deformity correction.

SUBMITTER: Ajuwon AA

PROVIDER: S-EPMC4481249 | biostudies-literature | 2015 Jul

REPOSITORIES: biostudies-literature

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Publications

An Anatomic Study on Whether the Patella is Centered in an Ideal Anteroposterior Radiograph of the Knee.

Ajuwon Ademola A AA Desai Ronak R Farhang Kathleen K Lasko Colin E CE Liu Raymond W RW

HSS journal : the musculoskeletal journal of Hospital for Special Surgery 20141202 2

<h4>Background</h4>Currently, an anteroposterior radiograph of the knee is judged based on a centered position of the patella between the femoral condyles. We are not aware of any anatomic literature supporting this recommendation.<h4>Questions/purposes</h4>Orthogonal images are required for accurate assessment of knee deformity. Although an image with the patella centered at the distal femur is generally accepted as a true anteroposterior (AP) radiograph of the knee, there is minimal anatomic d ...[more]

PMID: 26140030

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Project description:Background/objectiveGraft-tunnel length mismatch is a common intraoperative technical problem for anterior cruciate ligament reconstruction (ACLR) using a bone-patellar tendon-bone graft (BPTB). The patella-to-condyle and the patella-to-notch distances are two measurements in an anteroposterior knee radiograph. The objective of this study was to evaluate the sensitivities, specificities and reliabilities of those 2 measurements for detecting patients who had a patellar tendon length exceeding 45?mm.MethodsPreoperative plain radiographs of patients who underwent ACLR with a BPTB graft were evaluated independently by two orthopaedic surgeons 3 times each at 2-weekly intervals. The sensitivities and specificities of the two measurements for detecting patients who have a patellar tendon length exceeding 45?mm were calculated. The optimal cutoff point was estimated using Youden index, and the receiver operating characteristic (ROC) curve and area under the curve (AUC) were evaluated with a 95% CI. As for the inter- and intra-rater reliabilities, intraclass correlation coefficients (ICC) were determined.ResultsOne hundred and twenty-seven patients with an average age of 29.5 years old were evaluated. The mean patellar tendon length was 41.3?±?5.0?mm. Patients with a length more than 45?mm (20 patients, 16%) had significantly higher patella-to-condyle and patella-to-notch distances, and more frequent use of bone staples for distal graft fixation than patients with a length???45?mm. To detect patients with a patellar tendon length over 45?mm, the optimal cutoff point for the patella-to-condyle distance was set at 14.5?mm, which had a sensitivity of 80%, specificity of 71%, and AUC of 0.76. In the case of the patella-to-notch distance, the cutoff point of 5.5?mm had a sensitivity of 80%, specificity of 66%, and AUC of 0.73. The intra- and inter-rater reliabilities of the two measurements were excellent, with ICCs of over 0.90.ConclusionsPreoperative measurements of the patella-to-condyle and the patella-to-notch distances in AP knee radiographs can be valuable tools, with good sensitivities and specificities, for the determination of the patellar tendon length when using a BPTB graft for an ACLR. They had an acceptable level of discrimination capability and excellent reliability.

Project description:Pelvic sagittal inclination (PSI) is often evaluated in patients with hip pathology using lateral radiographs. However, it would be useful if PSI could be predicted from an anteroposterior radiograph since this film is ubiquitous in the evaluation of hip pathology. Herein, computer-modeling was applied to predict PSI from radiographic measurements assessed in the anteroposterior plane. Three-dimensional surface models of the pelvis, femur, and sacrum were reconstructed from computed tomography images of 50 women with hip dysplasia. This study cohort was selected as changes in PSI alter femoral head coverage, which is relevant to the diagnosis and treatment of hip dysplasia, a known cause of hip osteoarthritis. Five radiographic parameters commonly used to independently estimate PSI were evaluated after bone surfaces were projected to an anteroposterior plane, including the symphysis to sacrococcygeal joint distance (S-S distance), the pelvic foramen aspect ratio (PF ratio), the distance between the symphysis and a line connecting the femoral head centers (S-H distance), the sacro-femoral-pubic angle (SFP angle), and the pelvic vertical ratio (PVR). Regression models determined the ability of these parameters to predict PSI from -20° to 20° at 1° increment. All five parameters showed a strong correlation with the PSI (all r > 0.9). From the regression models, PSI was estimated with a median (maximum) absolute error of 3.6° (18.4°), 3.8° (17.7°), 5.2° (17.9°), 5.8° (28.8°), and 3.2° (23.5°) for the S-S distance, PF ratio, S-H distance, SFP angle, and PVR, respectively. The regression model for S-S distance had a mean slope of 2.18 that ranged from 1.98 to 2.41 when the sacrococcygeal joint was located superior to the symphysis. Results indicated that substantial errors occur when estimating the actual value of PSI from an anteroposterior radiograph. However, the change in PSI could be estimated from the S-S distance, which may aid surgeons to successfully increase head coverage through periacetabular osteotomy and to locate the acetabular cup in a functional position for total hip arthroplasty.

Dataset Information

An Anatomic Study on Whether the Patella is Centered in an Ideal Anteroposterior Radiograph of the Knee.

Background

Questions/purposes

Methods

Results

Conclusions

Publications

An Anatomic Study on Whether the Patella is Centered in an Ideal Anteroposterior Radiograph of the Knee.

Similar Datasets

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