Soft Tissue CAM Impingement in Adolescents: MRI reveals impingement lesions underappreciated on x-ray (138)

Objectives: The presence of femoroacetabular impingement (FAI) in adolescents has been established. However, the existence of a non-ossified CAM lesion in adolescent femoracetabular impingement (FAI) is not well described. The purpose of this study is to evaluate the presence of a non-ossified or soft CAM lesion in adolescent patients with FAI. Methods: A review of a prospective cohort of patients with symptomatic FAI in an institutional registry was performed. Subjects were included if they had an MRI and lateral x-ray of the hip (45o Dunn, Cross Table, or frog) at a baseline visit. On MRI, evaluation of the anterolateral femoral head was evaluated using radial, coronal, sagittal, or axial oblique sequences. When a soft CAM lesion was identified (all found between 2-5 o’clock), an alpha angle was performed on MRI and plain radiograph. The cohort of soft CAM lesions was reviewed and differences between radiographic and MRI alpha angles were assessed using a paired T-Test. Results: Thirty-one (9.3%) of 332 hips (mean age 16.4 yrs, range 13.66-19.59 yrs; 83.9% F) were identified with a soft impinging lesion at the femoral head-neck junction on MRI. The most common primary sport was track & field (4), the average duration of symptoms was 92.4 weeks and a majority with insidious onset (77.4%). The average alpha angle on MRI was greater than on x-ray [63.53 ± 7.94o vs 51.25 ± 7.92o; p<.05]. All subjects with soft CAM lesions demonstrated soft tissue consistent with extension of the physis (n=1),thickening of the peri-chondral ring (n=22), or thickening of the periosteum (n=8). Twenty-two of these patients (71%) with soft impingement underwent hip preservation surgery (n=13 labral repairs) with improvements in clinical outcome. Conclusions: In adolescent patients with symptomatic hip impingement, MRI may be useful to identify soft CAM lesions (non-ossified) that are under-represented on x-ray.

SOFT TISSUE CAM IMPINGEMENT IN ADOLESCENTS: MRI REVEALS IMPINGEMENT LESIONS UNDERAPPRECIATED ON X-RAY

Background: The presence of femoroacetabular impingement (FAI) in adolescents has been established. However, the existence of a non-ossified CAM lesion in adolescent femoracetabular impingement (FAI) is not well described. Hypthesis/Purpose: The purpose of this study is to evaluate the presence of a non-ossified or soft CAM lesion in adolescent patients with FAI. Methods: A review of a prospective cohort of patients with symptomatic FAI in an institutional registry was performed. Subjects were included if they had an MRI and lateral x-ray of the hip (45o Dunn, Cross Table, or frog) at a baseline visit. On MRI, evaluation of the anterolateral femoral head was evaluated using radial, coronal, sagittal, or axial oblique sequences. When a soft CAM lesion was identified (all found between 2-5 o’clock), an alpha angle was performed on MRI and plain radiograph. The cohort of soft CAM lesions was reviewed and differences between radiographic and MRI alpha angles were assessed using a paired T-Test. Results: Thirty-one (9.3%) of 332 hips (mean age 16.4 yrs, range 13.66-19.59 yrs; 83.9% F) were identified with a soft impinging lesion at the femoral head-neck junction on MRI. The most common primary sport was track & field (4), the average duration of symptoms was 92.4 weeks and a majority with insidious onset (77.4%). The average alpha angle on MRI was greater than on x-ray [63.53 ± 7.94o vs 51.25 ± 7.92o; p<0.05]. All subjects with soft CAM lesions demonstrated soft tissue consistent with extension of the physis (n=1),thickening of the peri-chondral ring (n=22), or thickening of the periosteum (n=8). Twenty-two of these patients (71%) with soft impingement underwent hip preservation surgery (n=13 labral repairs) with improvements in clinical outcome. Conclusion: In adolescent patients with symptomatic hip impingement, MRI may be useful to identify soft CAM lesions (non-ossified) that are under-represented on x-ray.

The Kinetics of Primary Alpha Plate Growth in Titanium Alloys

The kinetics of primary α-Ti colony/Widmanstätten plate growth from the β are examined in Ti-6246, comparing a simple quasi-analytic model to experiment. The plate growth velocity depends sensitively both on the diffusivity D(T) of the rate-limiting species and on the supersaturation around the growing plate. These result in a maxima in growth velocity around 40 K below the transus, once sufficient supersaturation is available to drive the plate growth. In Ti-6246, the plate growth velocity was found to be around 0.32 μm min−1 at 850 °C, which was in good agreement with the model prediction of 0.36 μm min−1. The solute field around the growing plates, and the plate thickness, was found to be quite variable, due to the intergrowth of plates and soft impingement. This solute field was found to extend to up to 30 nm, and the interface concentration in the β was found to be around 6.4 at. pct Mo. It was found that the increasing O content from 500 to 1500 wppm will have minimal effect on the plate lengths expected during continuous cooling; in contrast, Mo approximately doubles the plate lengths obtained for every 2 wt pct Mo reduction. Alloys using V as the β stabilizer instead of Mo are expected to have much faster plate growth kinetics at nominally equivalent V contents. These findings will provide a useful tool for the integrated design of alloys and process routes to achieve tailored microstructures.

A Mixed-Mode Model Considering Soft Impingement Effects for Solid-State Partitioning Phase Transformations

The original mixed-mode model is reformulated by considering the soft impingement effect and applying a general polynomial method of dealing with the concentration gradient in front of the interface. Comparison with the numerical solution shows that the reformulated mixed-mode model is more precise than the original model. The effect of soft impingement on the kinetics of partitioning phase transformation depends on both the growth mode and the degree of super-saturation.