Anatomical landmarks for safer carpal tunnel decompression: an experimental cadaveric study

Abstract

BackgroundCarpal tunnel syndrome is a common presentation to surgical outpatient clinics. Treatment of carpal tunnel syndrome involves surgical division of the flexor retinaculum. Palmar and recurrent branches of the median nerve as well as the superficial palmar arch are at risk of damage.MethodologyThirteen cadavers of Sri Lankan nationality were selected. Cadavers with deformed or damaged hands were excluded. All selected cadavers were preserved with the conventional arterial method using formalin as the main preservative. Both hands of the cadavers were placed in the anatomical position and dissected carefully. We took pre- determined measurements using a vernier caliper. We hypothesized that the structures at risk during carpal tunnel decompression such as recurrent branch of the median nerve and superficial palmar arch can be protected if simple anatomical landmarks are identified. We also hypothesized that an avascular area exists in the flexor retinaculum, identification of which facilitates safe dissection with minimal intra operative bleeding. Therefore we attempted to characterize the anatomical extent of such an avascular area as well as anatomical landmarks for a safer carpal tunnel decompression.Ethical clearance was obtained for the study.ResultsIn a majority of specimens the recurrent branch was a single trunk (n =20, 76.9%). Similarly 84.6% (n = 22) were extra ligamentous in location. Mean distance from the distal border of the TCL to the recurrent branch was 7.75 mm. Mean distance from the distal border of TCL to the superficial palmar arch was 11.48 mm. Mean length of the flexor retinaculum, as measured along the incision, was 27.00 mm. Mean proximal and distal width of the avascular area on TCL was 11.10 mm and 7.09 mm respectively.ConclusionWe recommend incision along the radial border of the extended ring finger for carpal tunnel decompression. Extending the incision more than 8.16 mm proximally and 7.75 mm distally from the corresponding borders of the TCL should be avoided. Incision should be kept to a mean length of 27.0 mm, which corresponds to the length of TCL along the above axis. We also propose an avascular area along the TCL, identification of which minimizes blood loss.

The double tunnels technique: an alternative minimally invasive approach for carpal tunnel syndrome

“…7 It is possible to mark on the palm of the hand the position of the superficial palmar arch and distal extent of the retinaculum. [6][7][8] Because the mean length of the flexor retinaculum is 2.7 cm, 28 it is possible to completely dissect the TCL without the risk of superficial palmar arch damage. During surgery it is also possible to perform an ultrasonographic evaluation to assess the complete section of the TCL.…”

“…Watchmaker 35 et al showed that the palmar cutaneous branch of the median nerve appears 2.09 ± 0.31 cm from the distal wrist crease. Samarakoon et al 28 revealed that the palmar incision must not be extended more than 8.16 mm from the proximal border of the TCL, to avoid inadvertently dividing the palmar cutaneous branch. Therefore, it is possible to avoid injuries of the recurrent branch and palmar cutaneous branch of the median nerve through a longitudinal palmar incision placed 5 mm ulnar and 6 mm radial to the junction between the longitude of the third finger and distal skin crease and extended not more than 8.16 mm proximally from the corresponding TCL border (safe area).…”

Carpal tunnel release: Safe and simple identification of the flexor retinaculum based on superficial anatomical landmarks

“…Since CTR is the most common performed surgery of the wrist and hand (Tung and Mackinnon, 2001;Soltani et al, 2013), the FR's relation to adjacent vascular and neurological structures (Olave et al, 2001;Chern et al, 2009;Samarakoon et al, 2014) as well as its detailed insertion points (Manley et al 2013) have already been defined. Despite its convenience, the FR has only been projected onto superficial landmarks by Yavuz et al (2013).…”

Identification of optimal site of G1 placement for median orthodromic palmar nerve conduction study

“…CTS is caused by compression of the median nerve as it courses under the transverse carpal ligament (TCL) . The TCL is 2–3 cm wide, and the proximal border is usually located at the level of the palmar wrist crease . It is generally believed that the nerve is most severely compressed at the proximal TCL.…”

“…4 The TCL is 2-3 cm wide, and the proximal border is usually located at the level of the palmar wrist crease. [4][5][6][7] It is generally believed that the nerve is most severely compressed at the proximal TCL. However, the precise site of the proximal border of the TCL, and therefore the exact site of compression of the median nerve, is variable.…”