Validating a Semi-Automated Technique for Segmenting Femoral Articular Cartilage on Ultrasound Images.

OBJECTIVE: To validate a semi-automated technique to segment ultrasound-assessed femoral cartilage without compromising segmentation accuracy to a traditional manual segmentation technique in participants with an anterior cruciate ligament injury (ACL). DESIGN: We recruited 27 participants with a primary unilateral ACL injury at a pre-operative clinic visit. One investigator performed a transverse suprapatellar ultrasound scan with the participant's ACL injured knee in maximum flexion. Three femoral cartilage ultrasound images were recorded. A single expert reader manually segmented the femoral cartilage cross-sectional area in each image. In addition, we created a semi-automatic program to segment the cartilage using a random walker-based method. We quantified the average cartilage thickness and echo-intensity for the manual and semi-automated segmentations. Intraclass correlation coefficients (ICC2,k) and Bland-Altman plots were used to validate the semi-automated technique to the manual segmentation for assessing average cartilage thickness and echo-intensity. A dice correlation coefficient was used to quantify the overlap between the segmentations created with the semi-automated and manual techniques. RESULTS: For average cartilage thickness, there was excellent reliability (ICC2,k = 0.99) and a small mean difference (+0.8%) between the manual and semi-automated segmentations. For average echo-intensity, there was excellent reliability (ICC2,k = 0.97) and a small mean difference (-2.5%) between the manual and semi-automated segmentations. The average dice correlation coefficient between the manual segmentation and semi-automated segmentation was 0.90, indicating high overlap between techniques. CONCLUSIONS: Our novel semi-automated segmentation technique is a valid method that requires less technical expertise and time than manual segmentation in patients after ACL injury.

Reliability of a Novel Semiautomated Ultrasound Segmentation Technique for Assessing Average Regional Femoral Articular Cartilage Thickness.

CONTEXT: Ultrasound imaging is a clinically feasible tool to assess femoral articular cartilage and may have utility in tracking early knee osteoarthritis development. Traditional assessment techniques focus on measurements at a single location, which can be challenging to adopt for novice raters. OBJECTIVE: To introduce a novel semiautomated ultrasound segmentation technique and determine the intrarater and interrater reliability of average regional femoral articular cartilage thickness and echo intensity of a novice and expert rater. DESIGN: Descriptive observational study. SETTING: Orthopedic clinic. PATIENTS OR OTHER PARTICIPANTS: Fifteen participants (mean [SD]; age 23.5 [4.6] y, height = 172.6 [9.3] cm, mass = 79.8 [15.7] kg) with a unilateral history of anterior cruciate ligament reconstruction participated. INTERVENTION: None. MAIN OUTCOME MEASURES: One rater captured anterior femoral cartilage images of the participants' contralateral knees using a transverse suprapatellar ultrasound assessment. The total femoral cartilage cross-sectional area of each image was segmented by a novice and expert rater. A novel custom program automatically separated the cartilage segmentations into medial, lateral, and intercondylar regions to determine the cross-sectional area and cartilage length. The average cartilage thickness in each region was calculated by dividing the cross-sectional area by the cartilage length. Echo intensity was calculated as the average gray-scale pixel value of each region. Two-way random effect intraclass correlations coefficient (ICC) for absolute agreement were used to determine the interrater reliability between a novice and expert rater, as well as the intrarater reliability of the novice rater. RESULTS: The novice rater demonstrated excellent intrarater (ICC [2,k] range = .993-.997) and interrater (ICC [2,k] range = .944-.991) reliability with the expert rater of all femoral articular cartilage average thickness and echo intensity regions. CONCLUSIONS: The novel semiautomated average cartilage thickness and echo-intensity assessment is efficient, systematic, and reliable between an expert and novice rater with minimal training.

State-of-the-art anterior cruciate ligament tears: A primer for primary care physicians.

The purpose of this article is to provide primary care physicians and other members of the medical community with an updated, general review on the subject of anterior cruciate ligament (ACL) tears. We aim to enhance awareness of these injuries and to prepare those practicing in the primary care setting to address these injuries. Because ACL injuries are quite common, it is very likely that a primary care physician will encounter these injuries and need to address them acutely. The current literature is replete with new concepts and controversies regarding ACL injuries, and this article provides a concise review for our target audience in regard to the care of a patient with an ACL injury. This article is composed of an overview with current epidemiologic data, basic anatomy and physiology, clinical presentation, physical examination findings, imaging modalities, and treatment options. After reading this short article, a medical care provider should understand ACL injuries and their appropriate management.