The Relationship Between the Intercrease Line and the A1 Digital Pulley: A Cadaveric Study

Morphological features of the chiasma tendinum and its relation with surface landmarks and pulleys: a cadaveric study

Aim

Chiasma tendinum (Camper’s chiasm) is of great importance in the delicate movements and stability of the fingers and takes place poorly in the literature. This study aims to reveal the morphometric details of the chiasma tendinum in relation with pulleys and other relevant structures.

Materials and methods

Palm and 2nd to 5th fingers of 10 (6 male, 4 female) formalin fixed cadavers were used bilaterally. After determining the superficial reference points on the fingers, the skin and the tendon sheath were incised, and then measurements of chiasma tendinum and related tendons were performed. The measurements were analyzed with respect to fingers, genders, and sides. Finally, the types of chiasma tendinum were identified and then grouped as symmetrical, asymmetrical, and pseudo chiasm.

Results

Pulley and chiasma tendinum positions were correlated with finger length (p < 0.01). Pulley lengths were significantly less in females. Asymmetrical chiasma tendinum types were found in 45% of the fingers. In most comparisons, values for fifth finger were significantly different than that of other fingers and chiasma tendinum types differed according to fingers and gender. The case of no fiber exchange was observed only in the 5th finger in 15%.

Conclusion

Findings related to the prediction of location of the pulleys and chiasma tendinum according to the superficial signs, awareness of cases where one of the two arms of the flexor digitorum superficialis is extremely thin and no fiber exchanges that may be risk factors for spontaneous tendon rupture may help provide more accurate approaches in relevant clinical applications.

Projection of the A1-Pulley of the Thumb onto Superficial Anatomical Landmarks: An Anatomical Study and a Useful Guide to Surgeons

BACKGROUND

The aim of our study was to project the A1-pulley of the thumb onto the total thumb length to enable its complete division with and without direct sight.

MATERIALS AND METHODS

The study involved 50 hands from adult human cadavers. The proximal and distal borders of the A1-pulley were measured with reference to the first metacarpophalangeal joint (MCPJ). The length of the thumb was defined as the interval between the first carpometacarpal joint (CMCJ) and the apex of the thumb. The length of the pulley is calculated proportionally with reference to the line between the first CMCJ and apex of the thumb.

RESULTS

Approximated by computing 95% confidence intervals, the pulley can be expected to lie in an area between 34.0% (proximal border) and 57.8% (distal border) alongside this line.

CONCLUSION

Percutaneous and minimally-invasive division of the A1-pulley needs to be performed between 34.0 and 57.8% of the length between the first CMCJ and apex of the thumb.