Clinical assessment of anatomical variation of flexor digitorum superficialis in the little finger

Objective: To determine the frequency of anatomical variation of flexor digitorum superficialis in the little finger, prevalence of isolated presence of 5th digit flexor digitorum superficialis tendon and interconnected presence of 4th and 5th digit flexor digitorum superficialis tendon, and to assess the association of anatomical variations with ethnicity. Method: The cross-sectional, descriptive study was conducted at the Bahria University of Health Sciences, Karachi, from August 2022 to May 2024, and comprised subjects of either gender aged 18-23 years belonging to five ethnic communities; Punjabi, Sindhi, Balochi, Pathan and Urdu-speaking. The presence of flexor digitorum superficialis was assessed using the Standard and Modified tests. Data was analysed using SPSS 27. Results: Of the 234 subjects with mean age 20.03±1.08 years, 146(62.4%) were females and 88(37.6%) were males. In terms of ethnicity, there were 163(69.65%) Punjabi subjects, 17(7.26%) Pathan, 13(5.55%) Sindhi, 12(5.12%) Balochi, and 29(12.40%) belonged to the Urdu-speaking community. Flexor digitorum superficialis was noted` in 150(64.1%) of the subjects. Agenesis was observed in 84(35.9%) individuals, with bilateral agenesis in 38(16.2%) and unilateral agenesis in 46(19.7%). The prevalence of right flexor digitorum superficialis showed non- differences (p>0.05) with respect to ethnicity, while the difference was significant on the left side (p=0.05). Significant differences (p=0.032) were observed on the left limb for the isolated presence of 5th digit flexor digitorum superficialis tendon and interconnected presence of 4th and 5th digit flexor digitorum superficialis tendon. Conclusion: There existed anatomical variability in terms of prevalence of flexor digitorum superficialis in the little finger with respect to ethnicity. Unilateral agenesis was more than bilateral agenesis, and active tendon function was more prevalent than interconnected function.