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. 2020 May 21;15(5):e0232988.
doi: 10.1371/journal.pone.0232988. eCollection 2020.

Computer tomographic analysis of anatomic characteristics of the ulna - essential parameters for preshaped implants

Johannes Christof Hopf  1 , Andreas Jähnig  1 , Tobias Jorg  2 , Ruben Sebastian Westphal  3 , Daniel Wagner  1 , Pol Maria Rommens  1
Affiliations

Computer tomographic analysis of anatomic characteristics of the ulna - essential parameters for preshaped implants

Johannes Christof Hopf et al. PLoS One. .

Abstract

Purpose: Anatomically preshaped implants are needed for exact restoration of the anatomy after fractures of the proximal ulna and ulnar shaft, which enables a good functional outcome. Aim of this computed tomographic analysis was to identify specific characteristics of the ulna. The data serve for the development of a new intramedullary implant for stabilisation of proximal and diaphyseal ulna fractures.

Methods: With a standardized research method 100 CT scans of the ulna were evaluated regarding anatomic parameters like width of the medullary canal, proximal ulna dorsal angulation and varus angulation. Also, correlations of these parameters were analyzed statistically.

Results: The mean proximal ulna dorsal angulation (PUDA) was 6.4° (SD 2.8°), while the mean varus angulation of the proximal ulna was 12.4° (SD 3.3°). The length of the ulna bone was 253.6 mm (SD 19.9 mm) on average. The average minimum diameter of the medullary canal was 4.2 mm (SD 1.1 mm) located at 141.3 mm (SD 19.7 mm) from the olecranon tip. There is a positive correlation between age and minimum diameter in our patient cohort (p< 0.001).

Conclusion: Our study described the anatomy of the proximal ulna and the ulna shaft with a reproducible research method in a representative patient cohort. The knowledge of the evaluated anatomic parameters can lead to an improvement of any implant design for the fixation of proximal and diaphyseal ulna fractures.

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Conflict of interest statement

The authors have declared that no competing interests exist.

Figures

Fig 1
Fig 1. Morphometric measurements.
a: Measurements of the proximal ulna varus angulation and apex of varus angulation; b: Proximal ulna dorsal angulation (PUDA) and apex of PUDA; c: Coronoid and olecranon heights; d: Diameter of the medullary canal in a 2d-slice with a maximum Hounsfield unit of 647.
Fig 2
Fig 2. PUDA histogram.
Histogram of the proximal ulna dorsal angulation (PUDA) of our patient cohort.
Fig 3
Fig 3. Varus angulation histogram.
Histogram of the proximal ulna varus angulation of our patient cohort.
Fig 4
Fig 4. Diameter of medullary canal.
Distribution of the maximum diameter of the medullary canal depending on the distance from the olecranon tip in boxplots.
Fig 5
Fig 5. PUDA in relation to ulnar length.
Histogram of the PUDA apex in relation to the total length of the ulna.
Fig 6
Fig 6. Diameter of medullary canal and age.
Scatterplot of the correlation of minimum diameter of the medullary canal and age in our patient cohort with regression line and estimated confidence interval.
Fig 7
Fig 7. Position of minimum diameter and age.
Scatterplot of the correlation of the position of the minimum diameter of the medullary canal and age in our patient cohort with regression line and estimated confidence interval.
See this image and copyright information in PMC

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