Anthropometric dimensions serve as critical tools in estimating height and bone length from skeletal remains, playing a pivotal role in forensic anthropology and medico-legal investigations. These measurements facilitate the identification of missing persons and provide insights into population health trends and body size variations.(1,2) The reconstruction of stature from skeletal elements has been a cornerstone of forensic practice since the early 19th century, with regression formulas derived from long bone lengths enabling accurate estimations.(3-5) In contemporary contexts, where fractures of long bones are increasingly common due to lifestyle changes and mechanical dependencies, understanding the vascular supply—via nutrient, periosteal, metaphyseal, and epiphyseal arteries—is essential for assessing fracture healing and pathological outcomes.(6) Anthropometry encompasses the quantitative assessment of human body dimensions, including muscles, adipose tissues, and bones, and has been employed by anthropologists and medical scientists for over a century to infer body size and stature.(7,8) Stature estimation from skeletal remains not only aids in health assessments across populations but also holds significant value in medico-legal scenarios for victim identification.(9) While pelvic and cranial bones are ideal for morphometric analysis in anthropological practice,(3) lower limb long bones such as the femur and tibia remain the gold standard for living stature reconstruction due to their robust correlation with height.(10,11) However, in cases where lower limb elements are absent or fragmented, upper limb bones—including the humerus, radius, and ulna—offer viable alternatives for stature and sex determination.(12) The humerus, the longest and strongest bone of the upper extremity, features an expanded proximal end (comprising the head, anatomical and surgical necks, greater and lesser tubercles, and intertubercular sulcus), a cylindrical shaft, and a distal end (including the capitulum, trochlea, radial and coronoid fossae, olecranon fossa, and medial and lateral epicondyles).(13) Its intact form and segmental morphology are invaluable for anatomists and forensic experts in skeletal identification, particularly in anthropology and forensic science where cranial or pelvic remains are unavailable.(14) Morphometric analysis of long bone fragments becomes indispensable when complete skeletons are not recoverable; for instance, proximal or distal humeral segments can be used to extrapolate total bone length for sex estimation and stature projection.(15,16) The distal humerus, with its trochlear asymmetry contributing to the elbow's carrying angle, is especially useful for sex determination due to sexual dimorphism in epicondylar breadth and trochlear dimensions.(17) Despite advancements in imaging and computational modeling, population-specific data on humeral segments remain limited, particularly for South Asian cohorts. Variations in segmental lengths—such as those between the humeral head and greater tuberosity or the olecranon fossa and trochlea—can influence forensic interpretations and orthopedic interventions, including fracture fixation and implant design.(18,19) Prior studies have highlighted bilateral asymmetries and ethnic differences in these parameters, underscoring the need for localized reference values.(20) This study aims to conduct a comprehensive morphometric analysis of humeral segments in an adult Indian population, providing baseline data to enhance forensic, anthropological, and clinical applications, including trauma evaluation and reconstructive surgery.

This cross-sectional observational study was conducted on archival dry adult human humeri sourced from established osteological collections, with measurements performed.(21) The study was carried out at the Departments of Anatomy, Government Medical Colleges (GMC), Nandyal and Kadapa. A total of 120 intact, dry adult human humeri (74 right-sided and 46 left-sided) were selected from the departmental bone collections, which primarily consist of bones from adult donors of South Indian ancestry. Inclusion criteria encompassed clean, undamaged, and complete adult humeri without evidence of pathological alterations, fractures, or developmental anomalies. Bones from subadult individuals, those with mechanical damage, fragmentation, or signs of post-mortem alteration were excluded to ensure measurement accuracy. Demographic details such as age, sex, and exact cause of death were unavailable for the archival specimens, precluding subgroup analyses based on these variables.(22) The primary exposure was the side (right or left) of the humerus, with the outcome being segmental morphometric dimensions. Measurements focused on six predefined parameters to assess proximal, shaft, and distal humeral morphology, selected based on their relevance to stature estimation and forensic reconstruction: (1) maximum humeral length, measured from the most superior point of the humeral head to the most inferior point of the medial epicondyle using an anthropometric board; (2) distance between the articular surface of the humeral head and the apex of the greater tuberosity (H1); (3) distance between the caput humeri and collum anatomicum (H2); (4) proximal-to-distal extent of the olecranon fossa (H3); (5) distance from the distal margin of the olecranon fossa to the proximal margin of the trochlea (H4); and (6) distance from the proximal margin of the olecranon fossa to the proximal margin of the trochlea (H5). All linear measurements were taken using vernier calipers with a precision of 0.01 mm. To enhance reliability, each measurement was performed twice by a single trained observer (K.J.), with discrepancies exceeding 0.5 mm resolved by a third measurement. Illustrations of the measurement landmarks are provided in Figure 1.(23) Potential sources of bias included selection bias due to the archival nature of the collection, which may not fully represent population variability, and measurement error from manual instrumentation. These were mitigated by restricting inclusion to intact bones from verified adult collections and employing standardized protocols with intra-observer verification. As demographic covariates were absent, no adjustments for confounding factors such as age or sex were possible, though this aligns with the descriptive aims of the study.(24) The sample size of 120 humeri was determined a priori based on power calculations from prior morphometric studies, aiming for a minimum detectable difference of 2 mm in segmental lengths with 80% power and alpha=0.05, assuming a standard deviation of 5 mm from comparable literature.(25) This yielded sufficient precision for descriptive statistics without subgroup stratification. Data were entered into a secure spreadsheet and analysed using SPSS version 16.0 (IBM Corp., Armonk, NY, USA). Continuous variables were summarized as mean ± standard deviation (SD). Bilateral comparisons were performed using independent-samples t-tests, with statistical significance set at p<0.05. No imputation was required for missing data, as all selected bones were fully measurable. Multivariable modeling was not undertaken due to the observational, descriptive design.(26)

Participants A total of 120 dry adult human humeri were included in the analysis, comprising 74 right-sided (61.7%) and 46 left-sided (38.3%) specimens. All bones were confirmed to be from adult individuals based on epiphyseal fusion and morphological maturity, with no exclusions occurring after initial selection. The sample was drawn from archival collections of South Indian origin, though individual demographic details (e.g., age, sex) were unavailable, limiting further stratification.(27) Descriptive Data The morphometric parameters assessed included maximum humeral length and five segmental distances, as detailed in the Methods. Measurements were obtained bilaterally, with data summarized by side to account for potential asymmetry. Overall, the mean maximum humeral length across all specimens was 301.9 ± 27.4 mm, reflecting typical adult dimensions in the studied population. Proximal segments (e.g., head to greater tuberosity) demonstrated low variability, indicative of conserved anatomical proportions, while distal segments (e.g., olecranon fossa to trochlea) showed slightly greater dispersion, consistent with functional adaptations at the elbow joint.(28) These values are presented in Table 1. Table 1. Segmental Morphometric Measurements of the Humerus (Mean ± SD, mm) Parameter Right (n=74) Left (n=46) p-value* Maximum length 302.6 ± 28.2 301.2 ± 26.4 0.78 H1: Articular head surface to greater tuberosity 7.3 ± 1.6 7.6 ± 1.3 0.32 H2: Caput humeri to collum anatomicum 41.1 ± 5.9 41.6 ± 7.2 0.75 H3: Proximal-to-distal extent of olecranon fossa 39.6 ± 1.2 40.3 ± 2.8 0.21 H4: Distal olecranon fossa to proximal trochlea 22.6 ± 2.6 23.4 ± 1.8 0.18 H5: Proximal olecranon fossa to proximal trochlea 23.1 ± 2.2 26.4 ± 2.8 0.001 *Independent-samples t-test for bilateral differences; p < 0.05 considered significant. Representative images of the humeri used in the study are shown in Figure 2, illustrating the intact morphology and measurement landmarks. Outcome Data and Main Results The primary outcome was the quantification of segmental lengths, which revealed consistent bilateral symmetry across most parameters. Maximum humeral length showed no significant difference between sides (p=0.78), averaging over 300 mm, which aligns with established norms for South Asian adults. Proximal measurements (H1 and H2) exhibited minimal asymmetry, with means of 7.3–7.6 mm for H1 and 41.1–41.6 mm for H2, reflecting stable glenohumeral articulation geometry. Distal segments (H3–H5) demonstrated greater precision in the olecranon fossa extent (H3: 39.6–40.3 mm), while H4 (22.6–23.4 mm) underscored the compact trochlear positioning essential for elbow stability. Notably, H5 showed a statistically significant leftward increase (26.4 mm vs. 23.1 mm; p=0.001), suggesting subtle lateralization in distal humeral architecture, potentially related to dominant-side biomechanics.(29) Overall variability (SD range: 1.2–7.2 mm) was low, supporting the reliability of these segments for forensic reconstruction. Other Analyses Subgroup analyses by side confirmed no additional asymmetries beyond H5, with effect sizes (Cohen's d) ranging from 0.05 (maximum length) to 0.52 (H5), indicating small to moderate clinical relevance. No outliers were identified via boxplot inspection, and normality assumptions (Shapiro-Wilk test, p>0.05 for all variables) supported parametric comparisons. These findings provide a robust dataset for population-specific benchmarks, with pooled means (right + left) yielding: maximum length 301.9 mm; H1 7.4 mm; H2 41.3 mm; H3 39.9 mm; H4 23.0 mm; and H5 24.4 mm.(30)

This study presents a comprehensive morphometric analysis of 120 adult dry human humeri, revealing baseline segmental measurements that underscore the humerus's role as a reliable proxy for stature estimation and skeletal identification. The maximum humeral length averaged 301.9 ± 27.4 mm, with no significant bilateral differences (p=0.78), aligning with anatomical expectations for adult South Indian populations. Proximal segments, such as the distance from the articular head surface to the greater tuberosity (H1: 7.4 ± 1.5 mm) and caput humeri to collum anatomicum (H2: 41.3 ± 6.5 mm), exhibited low variability (SD <7 mm), reflecting conserved glenohumeral morphology essential for shoulder stability. Distal segments demonstrated greater precision in the olecranon fossa extent (H3: 39.9 ± 2.1 mm; p=0.21) and trochlear positioning (H4: 23.0 ± 2.3 mm; p=0.18), while a notable leftward asymmetry in H5 (proximal olecranon fossa to proximal trochlea: 24.4 ± 2.7 mm overall; p=0.001) suggests potential biomechanical adaptations, possibly linked to handedness or load-bearing preferences. These findings provide a robust dataset for segmental reconstruction, particularly useful when intact bones are unavailable, and highlight the humerus's utility in bridging proximal and distal fracture assessments.(31) Interpretation The observed maximum humeral length of 301.9 mm closely mirrors values reported in prior South Asian cohorts, reinforcing population-specific norms. For instance, Prasad et al. (17) documented 302.8 ± 25.6 mm (right) and 296.8 ± 19.6 mm (left) in a comparable Indian sample, attributing minor discrepancies to regional dietary influences on bone robusticity. Similarly, Vinay et al. (12) reported 306.3 ± 21.2 mm (right) and 301.1 ± 22.4 mm (left) in South Indians, with our slightly shorter averages potentially reflecting sample age variability or archival preservation effects. In contrast, Sanjeev et al. (9) found a higher 307.6 ± 8.5 mm in a Bihar population, possibly due to their smaller sample (n=60) and focus on transverse/vertical head diameters (39.1 ± 1.3 mm and 41.4 ± 1.0 mm), which our proximal H1 (7.4 mm) complements by emphasizing tuberosity positioning for rotator cuff attachments. Distal measurements further illuminate ethnic and functional variances. Our H3 (olecranon fossa extent: 39.9 mm) exceeds Sanjeev et al.'s 18.4 ± 0.9 mm, likely stemming from differing landmarks—our proximal-to-distal fossa depth versus their edge-specific spans—highlighting methodological nuances in elbow joint morphometry.(9) H4 (22.6–23.4 mm) aligns with Prasad et al.'s 22.6 ± 1.3 mm (right) and 21.7 ± 1.8 mm (left),(17) supporting the trochlea's role in valgus carrying angle formation, as its medial flange depth influences ulnar articulation. Shaziya Afzal et al. (15) reported analogous distal metrics in 70 humeri, including medial-to-lateral epicondyle breadth (59.5 ± 2.5 mm right; 57.6 ± 3.5 mm left) and trochlear anteroposterior diameter (16.6 ± 1.5 mm right; 16.3 ± 1.2 mm left), which indirectly validate our H4/H5 asymmetry (p=0.001) as a dimorphic trait for sex estimation in trauma pathology. Internationally, Akman et al. (13) in a Turkish cohort (n=120) yielded comparable proximal values—H1: 6.5 ± 1.6 mm (right), H2: 41.0 ± 5.1 mm—but shorter distal segments (H3: 24.2 ± 2.0 mm; H4: 20.0 ± 2.2 mm), attributable to Mediterranean body proportions versus South Asian robusticity.(13) Jolly Agarwal et al. (14) noted left humeral lengths of 289.2 ± 23.9 mm and trochlear transverse widths of 22.1 ± 3.0 mm, echoing our distal consistency yet diverging in epicondylar distances (38.2 ± 4.0 mm trochlea-to-capitulum), possibly due to their emphasis on shaft curvature for implant fitting. Premjeet et al. (16) in 62 humeri reported head surface areas of 23.5–23.9 cm² and trochlear breadths of 26.4 mm, aligning with our H2 (41.3 mm) for proximal robustness but exceeding in shaft diameters (31.5–32.4 mm maximum), suggesting nutritional influences on cortical thickness. These congruences affirm the humerus's forensic value, as regression models from long bone fragments enhance stature prediction accuracy by 5–10% in fragmented remains.(32) Pathologically, our segmental data inform fracture line propagation: proximal H1/H2 variability (SD 1.5–6.5 mm) aids in distinguishing surgical neck fractures, while distal H3–H5 precision supports olecranon avulsion reconstructions.(33) Bilateral asymmetry in H5 may reflect adaptive remodeling from repetitive upper limb use, with implications for ergonomic pathology in occupational trauma. Overall, while our findings bolster existing literature, subtle deviations underscore the imperative for ethnicity-calibrated databases to refine medico-legal interpretations.(34) Limitations Several limitations temper the generalizability of these results. Foremost, the archival sample lacked demographic covariates (age, sex, stature), precluding stratified analyses and regression modeling for sex/stature prediction, a common constraint in osteological studies.(35) The unbalanced sidedness (74 right vs. 46 left) may amplify H5 asymmetry, though statistical power remained adequate (post-hoc power >0.80). Single-observer measurements, despite intra-rater reliability checks, introduce potential subjectivity, mitigated but not eliminated by caliper precision (0.01 mm).(36) Exclusion of pathological specimens restricts applicability to diseased states, such as osteoporosis-induced fractures, and the South Indian focus limits extrapolation to global populations. Finally, absence of 3D imaging overlooks volumetric asymmetries, warranting future multimodal approaches.(37) Generalizability These morphometric benchmarks are most applicable to South Asian adults, enhancing forensic pathology in regions with high skeletal recovery rates from disasters or conflicts. The segmental focus extends utility to fragmentary evidence, improving identification accuracy by 15–20% in incomplete assemblages.(38) Clinically, values inform orthopedic prosthetics and trauma simulations, particularly for elbow arthroplasty where trochlear mismatches elevate revision rates by 12%.(39) Broader validation across ancestries—e.g., via meta-analysis—could standardize global protocols, while integrating AI-driven landmarking may refine precision in real-time pathological assessments.(40) Ultimately, this study advocates for expanded osteological repositories to bridge anthropological and clinical domains.

This study provides baseline morphometric data for humeral segments, highlighting subtle bilateral differences. These findings may aid pathologists, anthropologists, and orthopedic surgeons in skeletal analysis, fracture pathology evaluation, and surgical planning.

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