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Morphological and Morphometric Analysis of Distal End of Ulna in Gujarat Region: A Cross-sectional Study |
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Shabina Dal, Kashyap Trivedi, Shailesh Patel 1. Resident Doctor, Department of Anatomy, Government Medical College, Bhavnagar, Gujarat, India. 2. Resident Doctor, Department of Anatomy, Government Medical College, Bhavnagar, Gujarat, India. 3. Professor and Head, Department of Anatomy, Government Medical College, Bhavnagar, Gujarat, India. |
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Correspondence Address : Shabina Dal, Plot No. 16 A, Behind Sanjivani Complex, Jailroad, Bhavnagar-364001, Gujarat, India. E-mail: Jarindin97@gmail.com |
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| ABSTRACT |  | |||||||||||||||||||||||||||||||||||
: Introduction: Distal end of the ulna is an important anatomical structure for normal hand functioning which is prone to damage such as fracture and avulsion of the ulnar styloid process, that causes distal radioulnar joint instability. Aim: To measure the morphometry and morphological variations of the distal end of ulna. Materials and Methods: A cross-sectional study was conducted in the Department of Anatomy, Government Medical College, Bhavnagar, Gujarat, India in August 2023. A total of 42 (21 on each side) distal end of dry human ulna of unknown gender, age and race were studied. Morphometric parameters include measurement of the Length of styloid process, Height of seat, width of pole and width of fovea with the help of digital vernier caliper. Morphological parameters include shape of styloid process and shape of pole. Descriptive statistics was used. Results: Mean length of styloid process on right and left side was 6±0.65 mm and 5.30±0.92 mm. Mean height of seat on right and left-side was 6.56±0.98 mm and 6.12±0.88 mm. Mean width of pole on right and left-side was 4.99±0.75 mm and 5.15±0.78 mm. Mean width of fovea on right and left-side was 2.58±0.42 mm and 2.68±0.46 mm, respectively. The majority shape of a pole was kidney (57.14%), followed by semicircular (19.04%), comma (16.66%) and semilunar (4.76%). Majority of styloid process was blunt (78.57%), followed by pointed (21.42%). Conclusion: The present study is useful for hand surgeons in dealing with distal ulnar injury and reconstruction of the distal radioulnar joint with prosthesis. | ||||||||||||||||||||||||||||||||||||
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| Keywords : Distal radio ulnar joint, Seat, Styloid process | ||||||||||||||||||||||||||||||||||||
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DOI and Others :
DOI: 10.7860/IJARS/2025/77435.3052
Date of Submission: Dec 20, 2024 Date of Peer Review: Feb 07, 2025 Date of Acceptance: Mar 20, 2025 Date of Publishing: May 01, 2025 AUTHOR DECLARATION: • Financial or Other Competing Interests: None • Was Ethics Committee Approval obtained for this study? No • Was informed consent obtained from the subjects involved in the study? No • For any images presented appropriate consent has been obtained from the subjects. NA PLAGIARISM CHECKING METHODS: • Plagiarism X-checker: Dec 21, 2024 • Manual Googling: Mar 15, 2025 • iThenticate Software: Mar 18, 2025 (16%) ETYMOLOGY: Author Origin EMENDATIONS: 6 |
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| INTRODUCTION |
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Lower end of ulna is made up of head and the styloid process. The head articulate with ulnar notch of the radius to form the inferior radioulnar joint (1). Ulna is separated from the wrist proper by a Fibrocartilagenous disc. The ulna is an important functional element of wrist and hand. The head of ulna has two articular surfaces for articulation with the radius which is known as the “seat.” The seat of the ulna encompasses two-thirds to three-quarter of the perimeter of the ulnar head and is covered with articular cartilage. Radius articular surface for ulna and the ulnar articular surface for the radius varies in shape and curvature (2). The ulnar styloid process is a medial bony projection easily palpated on the medial aspect of the wrist with the forearm supinated (2). The fovea is roughened depression at the base of styloid process on its radial aspect, that provide attachment for the apex of the triangular fibrocartilaginous complex (ligamentum subcruetum) (2). The relative length of radius and ulna are variable. The difference between the length of these bones is called ulnar variance. Ulnar variance is considered abnormal if there is >1 mm difference (2). It is widely accepted that hyperpronation is the typical mechanism of injury in ulnar dorsal dislocation of Distal radioulnar joint, whereas hypersupination is associated with ulnar volar dislocation (3). Galeazzi fracture-dislocation may involve a fracture of the ulnar shaft and styloid process in case of high-energy trauma. During sports activity forceful impact loading on the thenar side of the hand can lead to wrist hyperextension with ulnae deviation (3). Reduction in the length of ulna relative to the radius increases the load born by the lunate, causing compression against the distal radius. The compression is believed to initiate avascular necrosis of the lunate and this condition is known as Kienböck’s disease (3). Thus the present study aimed to assess morphometric and morphological parameters of the distal end of ulna that would help surgeons to enhance the outcome of ulnar prosthesis surgery. | ||||||||||||||||||||||||||||||||||||
| Material and Methods |
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A cross-sectional study was conducted in the Department of Anatomy, Government Medical College, Bhavnagar, Gujarat, India in August 2023. A total of 42 (21 on each side) distal end of dry human ulna of unknown gender, age and race were studied. Ethical committee of the Institute exempts the study regarding dry human bone. Inclusion and Exclusion criteria: All adult dried human ulna bones, irrespective of age, gender and race and completely intact bones were included in the study. Broken, unossified, decalcified and paediatric bones were excluded. Study Procedure Morphometric parameters include measurement of the length of the styloid process, the height of seat, the width of pole and the width of the fovea with the help of a digital Vernier caliper. Morphological parameters include shape of styloid process and shape of pole. All measurement was done by using digital Vernier caliper (accurate to 0.1 mm sensitivity). Each measurement was performed two times by a single observer. The following parameters were studied (Table/Fig 1),(Table/Fig 2)a-d. 1. The mean length of styloid process was measured from the tip to the base of the process. 2. Height of the seat was measured as the vertical distance between the upper margin and to lower margin of the seat. 3. Fovea was measured along the transverse axis meeting outermost point on the lateral margin of the fovea to the lateral end of the base of the styloid of the ulna. Width of fovea was measured in a transverse axis which is the distance between the base of styloid process to the lateral margin of fovea. 4. Pole was measured along the transverse axis as the distance between points where the transverse axis intersects the edge of the pole and the maximum width of pole was measured using a Vernier caliper. Morphological parameters include shape of styloid process and shape of pole. Statistical Analysis Descriptive statistics was used. Continuous variables were expressed as mean and categorical variables were expressed as frequency and percentages. | ||||||||||||||||||||||||||||||||||||
| Results |
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Morphometric parameters: Mean length of styloid process on right-side was 6±0.65 mm, while on left-side it was 5.30±0.92 mm (Table/Fig 3). Morphological parameters: Majority shape of a pole was kidney-shaped (57.14%), followed by semicircular (19.04%) (Table/Fig 4),(Table/Fig 5)a-d. Majority of styloid process is blunt (78.57%), followed by pointed (21.42%) (Table/Fig 6)a,b,(Table/Fig 7). | ||||||||||||||||||||||||||||||||||||
| Discussion |
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The lower end of the ulna is crucial for the proper function of the forearm and hand. The anatomical connection between the distal ulna, distal radius and ulnar carpus is highly precise and this relationship is essential for optimal functional performance. Even small change in this area leads to a significant alteration in load distribution and may result in pain syndrome and Distal Radioulnar Joint (DRUJ) instability (4). In the present study, the average length of the styloid process was 5.65±0.78 mm. A comparison of present study data with various studies is shown in (Table/Fig 8) (4),(5),(6). The present study shows that the styloid process was blunt in 78.57% of cases and pointed in 21.42%, while the study by Oommen SS showed 73% straight and 25% curved, which is similar to the present study (4). In Oommen SS study, kidney-shaped pole was common (84%) and the least common was coma shape (22%) (4). In Gupta C et al., study 48.55% of pole were kidney-shaped and 11.6% were semilunar-shaped (5). The congruence and range of motion at the DRUJ are determined by the size and slope of the seat. The dimensions and projection of the pole are critical for force transmission through the ulna, as the rotation at the DRUJ occurs around the base of the styloid process and the fovea. The size and vascularity of fovea play a significant role in pronation and supination movements. Additionally, the prominence of the Triangular Fibrocartilage Complex (TFCC) and the ulnar styloid process affect the range of wrist adduction and the impact of styloid impingement. Observation of the distal end of the ulna reveals four key components: the seat, pole, fovea and styloid process. Each component plays an important role in the anatomy and function of DRUJ at the wrist, with any change potentially leading to clinical conditions (7). Limitation(s) The present study has limitations regarding age and gender specificity of the ulna while analysing the bone, due to record constraints. | ||||||||||||||||||||||||||||||||||||
| Acknowledgement |
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The authors want to express their gratitude to the head and faculty members of the Department of Anatomy of Government Medical College, Bhavnagar for supporting the research project. The author is thankful to her colleague Dr. Kashyap Trivedi for helping throughout my project. | ||||||||||||||||||||||||||||||||||||
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