Introduction

Radius is a long bone located on the lateral side of forearm. The shaft widens rapidly toward the distal end, which is shallow anteriorly [1]. The proximal and distal ends of radius are commonly susceptible to trauma. Approximately 2-6% of fractures occur at the proximal end and the neck of radius, while the distal end fractures account for about 8-20% of radius fractures and more commonly seen in geriatric population [2]. However, distal end fractures are prevalent across all age groups, but the pediatric and elderly populations are considered at high risk.

Various studies have shown that up to 25% of fractures in children involve the distal end of the radius [3]. Adolescents are at higher risk due to a significant gap between skeletal growth and mineralization during puberty that may increase fragility with additional cortical porosity of radius and metaphysis[4]. The incidence of lower end fractures has been rising recently in elder population, largely due to an increasing number of falls among the elderly people accounting for up to 18% of all fractures in over 65 age group [5].Among the women population, postmenopausal women are particularly at risk because of calcium deficiency and decreased bone density associated with osteoporosis[6] and urban woman having 30% greater risk than rural women[7]. There are different types of distal radius fractures including Colles’ fracture which is a metaphyseal injury of the cortico-cancellous junction, characterized by dorsal tilt, shift, and impaction which occurs most commonly in elderly people. Smith's fractures involve palmar tilt, wrist joint injury involved Barton's fracture involved dorsal aspect of articular surface and Chauffer's fracture is an intra-articular fracture of radial styloid [8].

Apart from fractures, distal end of the radius is a common site for aggressive malignant tumor and it is treated by endoprosthesis, where correct surgical technique is essential for the desired outcome [9]. Following surgery, reduction in the radius length along with the altered palmar tilt causes considerable loss of movements in the forearm and wrist joint with decreased grip strength [10,11]. Indian studies in the Sindhudurg and Konkan regions of Maharashtra State show that approximately 39.9% of wrist fractures are treated surgically, which incurs considerable expenses [12]. Some studies have shown the concave shape of the anterior se distal radius and its angle relative to the plate design. However, there is still a lack of comprehensive morphological information regarding the anterior and inferior surfaces of the lower end of the radius [13-15]. While many morphological studies on the radius exist in the fields of forensic anthropology and orthopaedics, they often rely on radiographic images, where soft tissue shadows or angulation during imaging can alter the measured values [16].

A study on the morphology of the lower end of radius and its variations in Indian ethnicity is scarce. Therefore, it is necessary to review surgical methods for the distal part of the radius and carefully consider the shape of the anterior and inferior articular surfaces. A thorough understanding of the bony architecture, measurements, and their variations is crucial for designing various prosthetic plates, reconstructing the radio carpal joint and reducing post-surgical complications in wrist fracture surgery [17].

Aim and Objective

Aim: To analyse the morphology and morphometric features of distal end of radius for understanding their clinical implications in orthopedic practice.

Objective: The following parameters were studied morphologically and morphometrically.

a. Length of styloid process of radius.

b. Shape of lateral and medial facet of inferior articular surface of distal radius.

c. Circumferential diameter of distal end of radius.

Methods

The descriptive cross sectional study among 110 human dry radius bones which were segregated into 55 right and 55 left sides from the Department of Anatomy were used for the study. The study was approved by Institutional Ethical Committee, Vinayaka Mission’s Kirupananda Variyar Medical College and Hospitals, Salem, Tamil Nadu, India. The equipment used were vernier calipers, inelastic thread, measuring scale and digital photography camera.

The following parameters were measured on both right and left side:

a. Length of styloid process of radius: It was measured by using vernier caliper from tip of the styloid process to the lower vertical line of anterior border of radius bone (Fig: 1)

Fig 1: Measurement of length of Styloid Process of Radius (from the end of the anterior border to the tip of styloid process)	Fig 2: Measurement of Circumferential Diameter of Distal End of Radius (Encircle the thread 1cm above the upper margin of ulnar facet (UF) and measure  Circumferential Diameter)

b. Circumferential diameter of lower end of radius: It was measured by using an inelastic thread surrounding 1cm above the upper margin of ulnar notch of radius and thread was measured with normal ruler. (Fig: 2)

c. Shape of inferior articular facet of radius: All different shapes were documented (Fig: 3)

Fig 3: Various Shapes of Inferior Articular Facet (M=Medial, L=Lateral

d. Any abnormal bony variations in architecture were documented.

Inclusion criteria: Radius bones with intact lower end.

Exclusion criteria: Deformed and damaged lower end of radius bones.

Statistical Analysis:

Statistical parameters were analyzed with ‘SPSS software 16’. Standard deviation, mean values and the range were calculated from the obtained results. Paired sample t’ test was used to differentiate morphometric values between the right and the left sides of lower end of radius

Results

The mean length of the styloid process of the right side was 1.15cm, SD ± 0.16 cm with the variance of 0.03cm whereas the mean length of left side was 1.10cm, SD ± 0.14cm and variance was 0.02cm.

The mean circumferential diameter of right side was 8.70 cm SD ± 0.73cm and maximum and minimum mean circumferential diameter of right side were 10.30cm and 7.30 cm respectively. The mean circumferential diameter of left side was 8.47cm SD ± 0.75cm and maximum and minimum mean circumferential diameter of left side were 9.90cm and 6.60cm respectively.

The Shape of inferior articular facet in the inferior articular surface of distal radius varied from quadrangular in the medial facet (R = 92% L = 98%), triangular (R = 67 % L = 96 %) and oval (R = 32% L = 5.4 %) in the lateral facet.

Discussion

The distal end of radius is anatomically important as it forms wrist joint with scaphoid and lunate bones. It maintains the vertical position and supports the movements of forearm and hand [1]. The body weight is directly transmitted from the wrist joint to the radius, making the anatomy of the lower end of the radius of great clinical significance [18]. Fractures being common in the distal end[19]. Fractures are treated conservatively, but unstable fractures need surgical treatments, and proper positioning of the various components of the distal end of the radius during surgery is crucial to restoring normal wrist joint function, as improper positioning can lead to disability [20]. With proper diagnosis and treatment, satisfactory outcomes can be achieved even in severe injuries [21]. Therefore, knowledge of the anatomy of the distal articular surface of the radius is important for radiologists, oncologists and orthopaedic surgeons for accurately diagnosing clinical conditions affecting this region and in planning traumatic wrist surgeries.

In the present study, the mean length of the styloid process on the right side was found to be longer than on the left side which contrasts with findings in the Nepalese population, where the left side is longer than the right [22]. In the present study are in accordance with previous Indian studies, suggesting that clinicians should consider these values when performing wrist surgeries for fractures and designing prosthesis plates for the Indian population[20,24].

In the present study distal end circumference diameter was 8.70 ± 0.73 cm on the right side and 8.47 ± 0.73 cm on the left side in our study. The previous study reported mean circumference diameter of the distal radius was which were 8.40 ± 0.81 cm on the right side and 8.38 ± 0.79 cm on the left side [2]. The comparison of circumferential diameter of lower end of radius showed right side diameter was larger than the left side diameter its statistically significant p value (Table 3). The circumference diameter of the distal end of radius fractures are frequently articular injuries, resulting in disruption of both the radiocarpal and distal radioulnar joints. Even though these fractures may heal, there is a high incidence of malunion, joint disability, and instability. This emphasizes the importance of alignment correction, preservation of normal radial length, and reconstruction of the congruity of the radiocarpal and radioulnar joints [25].The smooth carpal articular surface is divided by a ridge into medial and lateral areas, with the medial area being quadrangular in shape and the lateral area being triangular [1].

This indicates that on the right bone, the predominant shape of the medial facets was quadrangular, while the lateral facets were mostly triangular. On the left side, the lateral facets were predominantly triangular and the medial facets were primarily quadrangular (fig: 3). Previous study stated that shape of the scaphoid facet was found to be triangular, and the lunate facet was quadrilateral in Indian study [20]. There is limited information available in the literature regarding the shapes of the facet. However, the structure of the scaphoid and lunate facet is crucial for diagnosing, treating fractures and dislocations, as well as identifying and correcting deformities such as Madelung deformity. To the best of our knowledge, details regarding the shapes of the facets on the right and left sides have not been documented in previous studies.

The tendon injuries, including both flexor and extensor tendons, are associated with volar plating of distal radius fractures [26]. Although tendon damage is influenced by the surgeon's skill and technique, improper measurements or anatomical variations can also alter the outcome.

Morphometric values of the distal end of the radius vary among different races, yet orthopaedic surgeons follow fracture treatment protocols and reference values based on western population, which may not be suitable for the Indian population [20] due to genetic variations, diet and nutrition that affects the bone mass and density. The restoration of normal range of motion, grip strength, and pain relief, as well as the prevention of post-traumatic arthritis caused by misalignment and complications such as tendon or nerve damage, all depend on proper alignment of fractures with accurate measurements of the lower end of the radius and the correct articular shape and surface.

Conclusions

This study aimed to analyze the measurements and shape variations of the distal end of the radius. In the present study data findings guiding as a reference for orthopedic surgeons and radiologist’s essential aiding in prosthetic and reconstructive surgeries and enhancing clinical outcomes.

Acknowledgements

The authors sincerely wish to thank the management, administrators and the Professor and Head of the department of Anatomy of Vinayaka Mission’s Kirupananda Variyar Medical College and Hospitals, Salem for their whole hearted support and permission to utilize the resources and conduct this study. The authors acknowledge the great help received from the scholars whose articles are cited and included in references of this manuscript. The authors are also grateful to authors, editors and publishers of all those articles, journals and books from where the literature for this article has been reviewed and discussed.

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