Abstract
Functional deficient of the little finger flexor digitorum superficialis (FDS-V) is known to be present in our population. The aim of this study is to evaluate the prevalence of the absence of FDS-V function in the Hong Kong Chinese population. The association between FDS-V absence and various variables (age, gender, hand dominance, occupation, smoking status, plamaris longus absence) were evaluated. The effects on the grip power due to FDS-V absence were analyzed. The anatomical variations were studied by cadaveric study. The clinical and anatomical variations were correlated by MRI study.
152 adult Chinese men and women from age 18 to 65 were recruited randomly. Subjects with congenital abnormalities, history of hand injury, history of upper limb surgery or underlying neuromuscular diseases were excluded. This study has 3 different parts. The first part is a clinical survey to determine the prevalence of the absence of FDS-V function by both the standard test and the modified test. The second part is a cadaveric study to determine the anatomical variations of FDS-V tendon by cadaveric dissection. The third part of this study is to correlate the clinical findings with MRI study.
Total 152 subjects were recruited with 51 male and 101 female, average age 37.6. The prevalence of the absence of FDS-V function by the standard test was 40.1% for right hand and 37.5% for left hand (38.8%). The prevalence of the absence of FDS-V function by the modified test was 9.2% on the right hand and 9.9% on the left hand (9.54%). The absence of FDS-V function was found more common to be bilateral than unilateral. This was found that 68.6% were bilateral by the standard test and 61% were bilateral by the modified test. The associations of functional FDS-V absence with various variables were insignificant. The effects of various variables on the grip power were analyzed using the multiple linear regression. Gender was1he only variable that had significant effects on the grip power for both the right and left hand. On either hand, the absence of Palmaris longus tendon and the absence of the FDS-V function had no significant effects on the grip power. Cadaveric study showed that the little finger FDS tendon was present in all 10 cadaveric hands. Abnormal muscle or tendon interconnection was not found. MRI study showed that there was hypoplastic tendon in subjects with absent FDS-V function.
The prevalence of the absence of FDS-V function in the Hong Kong Chinese population was 38.8% by the standard test and 9.54% by the modified test. The absence of little finger FDS function has no significant effects on the functional status as quantified by the grip power. We can postulate that patients with little finger FDS tendon injury can have normal range of motion and hand function if the FDP tendon is intact.
Correspondence should be addressed to: Associate Professor N. Susan Stott, Orthopaedic Department, Starship Children’s Hospital, Private Bag 92024, Auckland, New Zealand.
