The Reliability of Kaplan’s Cardinal Line as a Potential Surface Marker for the Superficial Palmar Arch During Carpal Tunnel Release - An Anatomical Study With Surgical Perspective

Oct 28, 2026

Kaplan’s cardinal line (KCL) is evaluated as a surface marker for the superficial palmar arch (SPA) during carpal tunnel release, with emphasis on determining KCL–SPA distances and their relation to other superficial landmarks. Sixty hands were dissected after drawing KCL using standard methods, measuring KCL–SPA distances along radial and ulnar ring-finger borders and the DWC–TCL distance. Significant correlation is reported between DWC–TCL and KCL–SPA, supporting KCL as a predictable limit for the distal incision.

LanguageEnglish

CategoryResearch & Report

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Reading Time23 min

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Abstract

Purpose

Methods

Results

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Open Access Original Article DOI: 10.7759/cureus.35144 Review began 01/31/2023 Review ended 02/10/2023 Published 02/18/2023 © Copyright 2023 Kaur et al. This is an open access article distributed under the terms of the Creative Commons Attribution License CC-BY 4.0. , which permits unrestricted use , distribution , and reproduction in any medium , provided the original author and source are credited. The Reliability of Kaplan’s Cardinal Line as a Potential Surface Marker for the Superficial Palmar Arch During Carpal Tunnel Release: An Anatomical Study With Surgical Perspective Harsimarjit Kaur 1 , Apurba Patra 2 , Manjeet Singh 3 , Gurdeep S. Kalyan 1 , Adil Asghar 4 1. Anatomy, Government Medical College Patiala, Patiala, IND 2. Anatomy, All India Institute of Medical Sciences, Bathinda, Bathinda, IND 3. Orthopedics, Maharishi Markandeshwar Institute of Medical Sciences and Research, Ambala, IND 4. Anatomy/Orthopedics, All India Institute of Medical Sciences, Patna, Patna, IND Corresponding author: Apurba Patra, [apurba.cnmc03@gmail.com](apurba.cnmc03@gmail.com) Abstract Purpose Kaplan 's cardinal line (KCL) provides a more accurate reference point to the superficial palmar arch (SPA) . The aim was to determine the KCL-SPA distances and their relationship with the other defined superficial landmarks, such as distal wrist crease (DWC) or distal portion of the transverse carpal ligament (TCL) or DWC-TCL distance. The objective was to determine the distal limit of the incision made during carpal tunnel release (CTR) . Methods Sixty hands were dissected after KCL was drawn on each hand using standard methods. The distance from KCL to the SPA was measured along the radial and ulnar borders of the ring finger and recorded as radial and ulnar KCL-SPA distance, respectively. The distance between the DWC and the distal portion ofthe TCL was also measured (DWC-TCL) . Correlation analysis was done between the DWC-TCL and KCL-SPA distance. The ratios between the radial and ulnar KCL-SPA distance and DWC-TCL distance were calculated and mentioned as radial and ulnar Kaplan cardinal index, respectively. Results KCL-SPA distance was 6.8±3.7 mm along the radial border and 6 .6±3.6 mm along the ulnar border of the ring finger. The DWC-TCL distance was 29.4± 1.2 mm. The means of radial and ulnar Kaplan cardinal indices were 0.23 and 0 .22, respectively. A significant correlation was found between the DWC-TCL distance and the KCL-SPA distances. Conclusion Clinically, KCL can be appraised as a predictable surface landmark in limiting the distal-most extent of the incision during CTR and protecting SPA from transection. The SPA was found to lie at a variable distance from the KCL, and the minimum distance was found to be 3.3 mm. This should be considered as the maximum permissible extension of CTR incision beyond KCL. Categories: Anatomy Keywords: superficial palmar arch, topography, hand surgery, carpal tunnel, anatomical landmark Introduction Clinicians, especially surgeons, use surface marking as an important tool to make out a picture of underlying structures to avoid undue complications during procedures. In hand surgery, carpal tunnel release (CTR) isone of the commonly performed outpatient procedures both by open and endoscopic approach. Although CTR is comparatively a simple and superficial procedure, the chances of fatal complications, such as inadvertent injury to the superficial palmar arch (SPA), are not uncommon. SPA, a superficial continuation of the ulnar artery, runs transversely from the ulnar side to the radial side to join with its radial counterpart and make the arch complete. Variability in its location and perpendicular position to the line of incision in CTR makes it vulnerable to cut [1] . So, the preciseness of the incision, especially the distal limit of the incision, is the key step in preventing iatrogenic injury and establishing a desirable outcome. The line of incisions a

FAQs

What was the study’s primary purpose regarding Kaplan’s cardinal line?

To determine the KCL–SPA distances and their relationship with superficial landmarks such as the distal wrist crease and the distal portion of the transverse carpal ligament, aiming to define the distal limit of the incision in carpal tunnel release.

How were the measurements performed in the methods section?

After KCL was drawn on each hand, distances from KCL to the SPA were measured along radial and ulnar borders of the ring finger, and the distance between the distal wrist crease and the distal portion of the transverse carpal ligament (DWC–TCL) was also measured.

What were the key findings and clinical implication?

KCL–SPA distance averaged about 6.8 mm (radial) and 6.6 mm (ulnar), and DWC–TCL showed a significant correlation with KCL–SPA distances. The authors conclude that KCL can serve as a predictable surface landmark to limit the distal extent of incision and help protect the SPA from transection.

Oct 28, 2026

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