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The flexor synovial sheath anatomy of the little finger: a macroscopic study
C S Phillips1, R Falender, D P Mass
1University of Chicago Hospital, Department of Surgery, IL 60637-1470, USA.
Abstract:
Anatomy texts describe the flexor synovial sheath of the little finger as extending proximally into the palm to join with the ulnar bursa in 80% of cases. Based on this, one would expect frequent extension of little finger flexor synovial sheath infections into the forearm. Methylene blue injection followed by open tenogram was used to define the anatomy of the flexor synovial sheath of the little finger in 60 cadaver hands. In 27 hands, the flexor synovial sheath extended proximally from the bony profundus tendon insertion to terminate at the palmar aponeurosis pulley. A stricture of varying length separated the flexor synovial sheath from the more proximal ulnar bursa. In 19 hands, the flexor synovial sheath was continuous with the ulnar bursa, conforming to the conventional textbook description. In 14 hands, the flexor synovial sheath stopped at the proximal border of the A1 pulley. An inconsistent defect from 1 to 10 mm was noted. The clinical implications of these findings suggest that many little finger flexor synovial sheath infections, when caught early and after careful physical examination, need only be managed by drainage at the distal palmar level.
Insights
Anatomical study reveals the flexor synovial sheath of the little finger often terminates before reaching the ulnar bursa. This suggests many little finger infections may only require distal palmar drainage for effective treatment.
Area of Science:
- Anatomy
- Hand Surgery
- Infectious Disease
Background:
- Conventional anatomical descriptions state the flexor synovial sheath of the little finger joins the ulnar bursa in most cases.
- This anatomical understanding implies frequent proximal spread of little finger infections into the forearm.
Purpose of the Study:
- To precisely define the proximal extent of the flexor synovial sheath of the little finger.
- To clarify the relationship between the flexor synovial sheath and the ulnar bursa.
- To inform clinical management of little finger flexor synovial sheath infections.
Main Methods:
- Methylene blue injection into the flexor synovial sheath of 60 cadaver hands.
- Open tenography to visualize the sheath's extent and relationship with the ulnar bursa.
Main Results:
- In 27 hands, the sheath extended to the palmar aponeurosis pulley, separated from the ulnar bursa by a stricture.
- In 19 hands, continuity with the ulnar bursa was observed, aligning with textbook descriptions.
- In 14 hands, the sheath terminated at the A1 pulley, with inconsistent defects noted.
Conclusions:
- The flexor synovial sheath of the little finger exhibits variable proximal extension.
- A significant portion of cases do not show direct continuity with the ulnar bursa.
- Early-stage little finger flexor synovial sheath infections may be effectively managed with distal palmar drainage.