The area method for measuring acetabular cup anteversion: An accurate and autonomous solution.

Several radiological methods of measuring anteversion of the acetabular component after total hip arthroplasty have been described, all time-consuming and with varying reproducibility. This study aimed to compare the recently proposed Area method to true cup anteversion as determined by an accelerometer. This study further applied this method programmatically to autonomously determine radiographic cup orientation using two computer programs, then compared these results to hand and accelerometer measurements. 160 anteroposterior pelvis radiographs were taken of a standard Sawbones® pelvis fitted with a total hip arthroplasty system. The acetabular cup was re-oriented between each radiograph, with anteversion ranging from 0° to 90°. An accelerometer was mounted to the cup to measure true cup anteversion. Radiographic anteversion was independently measured via three methods: by hand, linear image processing, and machine learning. Measurements were compared to triaxial accelerometer recordings. Coefficient of determination (R2) was found to be 0.997, 0.991, and 0.989 for hand measurements, the machine learning, and linear image processing, respectively. The machine learning program and hand measurements overestimated anteversion by 0.70° and 0.02° respectively. The program using linear techniques underestimated anteversion by 5.02°. Average runtime was 0.03 and 0.59 s for the machine learning and linear image processing program, respectively. The machine learning program averaged within 1° of cup orientation given a true cup anteversion less than 51°, and within 2° given an anteversion less than 85°. The Area method showed great accuracy and reliability with hand measurements compared to true anteversion. The results of this study support the use of machine learning for accurate, timely, autonomous assessment of cup orientation.

Acute fibular sesamoid fracture: one part of the spectrum of sesamoid pathologies.

A 35-year-old male athlete presented with acute pain plantar to the hallux metatarsophalangeal joint following jumping to catch a basketball.

Metaphyseal and diaphyseal chondroblastomas.

OBJECTIVE: Epiphyseal/apophyseal locations are important diagnostic radiological features of chondroblastomas (CB). Although the tumor may secondarily involve the metaphysis, reports of primary metaphyseal or diaphyseal CB without any epiphyseal or apophyseal involvement are exceptionally rare and frequently present as a diagnostic dilemma. The purpose of this study was to present seven cases of pure metaphyseal and/or diaphyseal CB along with a review of pertinent literature. METHODS: A retrospective review of databases at two major referral centers revealed 390 cases of CB between 1960 and 2009. Out of these, seven histologically proven CB cases (1.8%) were found to be radiologically located in metaphysis and/or diaphysis, without involving the epiphysis and/or apophysis, and formed the study cohort. RESULTS: There were four males and three females (age range 2-25 years). Locations included proximal femur (n = 1), distal femur (2), proximal humerus (2), clavicle (1), and proximal radius (1). All lesions showed marginal sclerosis. A periosteal reaction was seen in five cases (71%), cortical expansion in four cases (57%), and chondroid matrix in four cases (57%). A CT (two cases) demonstrated a matrix in both cases. An MR (one case) showed extensive perilesional edema. Bone scan (one case) showed intense uptake. CONCLUSION: Pure metaphyseal and/or diaphyseal CB are exceedingly rare. A presumptive diagnosis may be considered in the appropriate age group in the presence of chondroid matrix, perilesional edema, periosteal reaction, and marginal sclerosis. Regardless of all the diagnostic possibilities, biopsy may still be required. However, knowledge of this entity will help make the final diagnosis and guide the correct treatment.