Ajith Peiris Malalasekera

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

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.

Extra and Intramuscular Distribution of the Thoracodorsal Nerve with Regard to Nerve Reconstruction Surgeries

Background The lateral branch of the thoracodorsal nerve (LBTN) is used for nerve transfer in facial, musculocutaneous, axillary nerve injuries and for irreparable C5, C6 spinal nerve lesions and accessory nerve defects. For a successful surgical outcome, the nerve to be used in nerve transfer should be of adequate length and thickness for nerve coaptation. Aim Our objective was to evaluate the length of the LBTN that could be obtained as a donor nerve, externally and within the muscle. Method Eight (8) cadavers with intact upper limbs and thorax which could be positioned in the anatomical position were selected for the study. Cadavers with dissected axillae, brachial plexus or upper limbs were excluded. The thoracodorsal neurovascular bundle was dissected and the number of branches of the thoracodorsal nerve was identified along with its lateral branch. The lateral branch was dissected up to the latissimus dorsi muscle and further intramuscularly. All lengths were measured using a vernier caliper. Results The mean length of the LBTN, up to its first intramuscular branch, is 8.14 cm (range 5.99-12.29 cm). Beyond this, the intramuscular nerve branched further and was of very minute diameter. The mean unbranched intramuscular length of the nerve is 3.36 cm (range 1.3-7.71 cm) which is 41.28% of the total length of the LBTN. Conclusion A significant proportion of the LBTN is found within the latissimus dorsi muscle. This length could potentially be used for direct nerve coaptation by intrafascicular dissection.

Morphological variations of the human ejaculatory ducts in relation to the prostatic urethra: Morphological Variations of the Human Ejaculatory Ducts

Loss of ejaculation can follow transurethral resection of the prostate (TURP). Periverumontanal prostate tissue is preserved in ejaculation‐preserving TURP (ep‐TURP). Knowledge of ejaculatory duct anatomy in relation to the prostatic urethra can help in ep‐TURP. This was evaluated in cross‐sections of the prostate using a 3 D model to determine a safe zone for resecting the prostate in ep‐TURP. A 3 D reconstruction of the ejaculatory ducts was developed on the basis of six prostate gland cross‐sections. The measurements obtained from the 3 D model were standardized according to the maximum width of the prostate. Simple linear regressions were used to predict the relationships of the ejaculatory ducts. The maximum widths of the prostates ranged from 22.60 to 52.10 mm. The ejaculatory ducts entered the prostate with a concavity directed posterolaterally. They then proceeded toward the seminal colliculus in a fairly straight course, and from that point they angulated anteromedially. As they opened into the prostatic urethra they diverged. Significant regression models predicted the relationships of the ejaculatory ducts to the prostatic urethra based on the sizes of the prostates. The 3 D anatomy of ejaculatory ducts can be predicted on the basis of prostate width. The ejaculatory ducts can be preserved with 95% accuracy if a block of tissue 7.5 mm from the midline on either side of the seminal colliculus is preserved, up to 10 mm proximal to the level of the seminal colliculus, during TURP. Clin. Anat. 31:456–461, 2018.