Publications by authors named "Zachary R Ashwell"

6 Publications

  • Page 1 of 1

Combined Lateral Osseolabral Coverage Is Normal in Hips With Acetabular Dysplasia.

Arthroscopy 2019 03 4;35(3):800-806. Epub 2019 Feb 4.

Department of Orthopedics, University of Colorado School of Medicine, Aurora, Colorado, U.S.A.

Purpose: To compare the lateral osseolabral coverage between groups of patients with different degrees of acetabular bony coverage using a magnetic resonance imaging parameter known as the combined lateral center-edge angle (cLCEA).

Methods: The cLCEA was measured among a consecutive series of patients presenting to a dedicated hip preservation surgeon with a magnetic resonance imaging scan. The cLCEA was measured using a coronal T1 or proton density image and was defined as the angle subtended by (1) a line through the center of the femoral head and orthogonal to the transverse line passing through the teardrops of both hips and (2) an oblique line drawn from the center of the femoral head to the free edge of the lateral acetabular labrum. The average difference between the lateral center-edge angle (LCEA) and the cLCEA was calculated and compared between groups based on acetabular bony coverage: dysplasia (LCEA <20°), borderline dysplasia (LCEA 20°-24.9°), normal coverage (LCEA 25°-39.9°), and overcoverage (LCEA ≥40°).

Results: In total, 341 patients (386 hips) were included. There were no significant differences in cLCEA between hips with normal acetabular coverage and dysplasia (P = .10) or borderline dysplasia (P = .46). Despite the large difference in mean LCEA between dysplasia (14.8° ± 3.9°) and acetabular overcoverage (43.1° ± 2.8°), the mean cLCEA values exhibited only a modest difference (44.7° ± 4.9° vs 52.7° ± 4.5°, respectively). Concordantly, hips with dysplasia exhibited the largest difference between mean LCEA and cLCEA (delta = 29.9° ± 4.7°) and hips with acetabular overcoverage had the smallest difference between measures (9.6° ± 5.2°).

Conclusions: With decreasing acetabular bony coverage, there is increasing labral size such that the total osseolabral coverage, measured by the combined LCEA, remains equivalent between hips with normal acetabular coverage versus dysplasia.

Level Of Evidence: Level III, retrospective comparative study.
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http://dx.doi.org/10.1016/j.arthro.2018.10.133DOI Listing
March 2019

Gymnast's wrist in a 12-year-old female with MRI correlation.

Radiol Case Rep 2019 Mar 14;14(3):360-364. Epub 2018 Dec 14.

University of Washington, Department of Radiology, Musculoskeletal Radiology Division, UW Medical Center - Roosevelt, 4245 Roosevelt Way NE Box 354755, Seattle, WA 98109, USA.

We describe a case of chronic overuse injury of the distal radial physis (gymnast's wrist). While the radiographic appearance of this entity has been reported, there are limited studies highlighting the MR appearance of this entity. This lesion is being seen with increasing frequency in young, elite gymnasts. If this injury goes unrecognized, there is potential for abnormal osseous development, with premature physeal fusion, abnormal joint inclination and even Madelung deformity.
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http://dx.doi.org/10.1016/j.radcr.2018.09.010DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6297268PMC
March 2019

The Iliofemoral Line: A Radiographic Sign of Acetabular Dysplasia in the Adult Hip.

Am J Sports Med 2017 Sep 13;45(11):2493-2500. Epub 2017 Jun 13.

Department of Orthopedics, University of Colorado School of Medicine, Aurora, Colorado, USA.

Background: Several radiographic parameters utilized for the diagnosis of acetabular dysplasia in adults suffer from poor reproducibility and reliability.

Purpose: To define and validate a novel radiographic parameter (the iliofemoral line [IFL]) for the detection of frank and borderline hip dysplasia and to compare the sensitivity and specificity of this radiographic marker to those of previously validated qualitative parameters.

Study Design: Cohort study (diagnosis); Level of evidence, 2.

Methods: A consecutive cohort of 222 adult patients (436 hips) undergoing hip preservation surgery was included. The IFL, which extends from the lateral femoral neck through the inner cortical lip of the iliac crest, intersects the femoral head in cases of dysplasia. Percent medialization of the IFL was defined as the horizontal distance of the exposed femoral head lateral to the IFL, relative to the horizontal femoral head width at the center of the femoral head.

Results: Percent medialization of the IFL was strongly correlated to the lateral center edge angle ( P < .0001). Values of percent medialization ranging from 15% to 22% predicted the presence of borderline hip dysplasia with a sensitivity of 62% and specificity of 89%, while values exceeding 22% predicted the presence of frank acetabular dysplasia with a sensitivity of 77% and specificity of 94%. By comparison, abnormality of the Shenton line demonstrated a sensitivity of 3.7% and specificity of 97% for the detection of borderline dysplasia and a sensitivity of 16% and specificity of 99% for the detection of frank acetabular dysplasia. Compared with the Shenton line, percent medialization of the IFL was significantly more sensitive for the detection of both borderline and frank acetabular dysplasia (both P < .0001). The intraobserver and interobserver reproducibility of the horizontal difference outside the IFL were 0.99 and 0.96, respectively.

Conclusion: Percent medialization of the IFL is a reliable and accurate radiographic marker of frank acetabular dysplasia and, to a lesser extent, borderline dysplasia. The use of this radiographic parameter as an additional tool may enable the earlier detection of borderline and frank hip dysplasia in young adults presenting with hip pain.
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http://dx.doi.org/10.1177/0363546517708983DOI Listing
September 2017

Lateral acetabular coverage as a predictor of femoroacetabular cartilage thickness.

J Hip Preserv Surg 2016 Oct 10;3(4):262-269. Epub 2016 Nov 10.

Department of Orthopaedics, Division of Sports Medicine and Hip Preservation, University of Colorado School of Medicine, Aurora, CO 80045, USA.

To investigate the correlation between femoroacetabular cartilage thickness and lateral acetabular coverage in patients undergoing hip arthroscopy for a variety of indications. Articular cartilage at the hip is hypothesized to undergo adaptive change secondary to unique patterns of pathomechanical loading which results in a direct relationship between acetabular coverage and femoroacetabular cartilage thickness. A cohort of 252 patients presenting to our dedicated hip preservation service between June 2013 and June 2015 were retrospectively analysed. Preoperative radiographs and MRI studies were obtained for all symptomatic hips and classified according to radiographic lateral center edge angle (LCEA) as follows: normal acetabular coverage (25-40°), acetabular overcoverage (≥40°), borderline dysplasia (20-24.9°) and frank dysplasia (<20°). Femoroacetabular cartilage thickness was measured on a preoperative MRI-scan at the fovea, middle sourcil, and lateral sourcil. In all groups, cartilage thickness was maximized at the lateral sourcil relative to the middle sourcil or fovea ( < 0.001). Furthermore, articular cartilage thickness was significantly increased when comparing one group to successive groups with diminished lateral acetabular coverage. Indeed, multivariate analyses confirmed LCEA to be the strongest determinant of femoroacetabular cartilage thickness compared with age, gender, body-mass index or presence of cam/pincer lesions. Patients with borderline and frank dysplasia exhibit increased values of femoroacetabular cartilage thickness in the weight-bearing zone, potentially indicating a compensatory reaction to the lack of bony coverage. Articular cartilage thickness may serve as an instability marker and inform clinical decision-making for patients with borderline dysplasia.
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http://dx.doi.org/10.1093/jhps/hnw034DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5883176PMC
October 2016

Unique Utility of Sonography for Detection of an Iatrogenic Radial Nerve Injury.

J Ultrasound Med 2016 May 23;35(5):1101-3. Epub 2016 Mar 23.

Department of Radiology, University of Colorado School of Medicine, Aurora, Colorado USA.

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http://dx.doi.org/10.7863/ultra.15.07053DOI Listing
May 2016

Upper-limb joint power and its distribution in spinal cord injured wheelchair users: steady-state self-selected speed versus maximal acceleration trials.

Arch Phys Med Rehabil 2007 Apr;88(4):456-63

Department of Rehabilitation Medicine, University of Washington, Seattle, WA 98053, USA.

Objective: To compare upper-limb joint power magnitude and distribution between the shoulder, elbow, and wrist during maximal acceleration (MAC) versus steady-state, self-selected speed (SSS) manual wheelchair propulsion.

Design: Cross-sectional biomechanic study.

Setting: Research university and teaching hospital.

Participants: Volunteer sample of 13 manual wheelchair users with spinal cord injury below T1.

Interventions: Not applicable.

Main Outcome Measures: Propulsive joint power magnitude and fractional distribution among upper-limb joints.

Results: Wilcoxon signed-rank testing revealed shoulder power was larger for MAC versus SSS (median peak, 101.5W; interquartile range [IQR], 74.6; median peak, 37.7W; IQR, 22.9; respectively) (P<.01). Elbow and wrist power were unchanged. Peak shoulder power fraction was larger for MAC versus SSS (median peak, 1.055; IQR, .110 vs peak, .870; IQR, .252) (P<.01). Peak elbow power fraction was smaller for MAC versus SSS (median peak, -.012; IQR, .144 vs peak, .146; IQR, .206) (P<.05). Peak wrist power fraction was smaller for MAC versus SSS (median peak, -.058; IQR, .057 vs peak, -.010; IQR, .150) (P<.05).

Conclusions: Power at the shoulder was larger than at other joints. Peak shoulder joint power and power fraction was larger during MAC versus SSS propulsion. Elbow and wrist power fractions were smaller for MAC versus SSS propulsion. Higher joint power, present under MAC, may predispose manual wheelchair users to injury, particularly at the shoulder.
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http://dx.doi.org/10.1016/j.apmr.2007.01.016DOI Listing
April 2007