# A Comparative Study of the Presence of the Palmaris Longus Tendon Using Physical and Ultrasound Examination

## TL;DR

This study compares physical exams and ultrasound for detecting the palmaris longus tendon, finding ultrasound more accurate.

## Contribution

The study introduces a direct comparison between physical examination and ultrasound for PLT detection, highlighting ultrasound's superior accuracy.

## Key findings

- Ultrasound detected the PLT in 72.13% of wrists bilaterally and 5.74% unilaterally.
- Physical exams detected the PLT in 56.28% of wrists bilaterally and 6.56% unilaterally.
- Ultrasonography showed significantly higher accuracy than physical examination methods.

## Abstract

Introduction

The palmaris longus muscle (PLM), located in the forearm's anterior compartment, plays an essential role in wrist flexion. Its tendon is often used for grafting because of its accessibility and minimal function. However, its anatomy varies, with congenital absence being the most common variation. This study aims to detect the incidence of the palmaris longus tendon (PLT) and compare physical examination methods with standard ultrasonography, as previous studies have only utilized physical examinations.

Methods

In this study, 61 participants were examined bilaterally (122 wrists) using three different physical examination methods: the Schaeffer, Thompson, and Mishra I tests. The ultrasonography test was conducted by a single observer using a GE LOGIQ e ultrasound system (GE HealthCare Technologies, Inc., Chicago, IL, USA), equipped with a linear transducer with a frequency range of 12-15 Hz, attached transversely to the anterior distal forearm. The tendon was visualized anterior to the median nerve, medial to the flexor carpi radialis, and superficial to the flexor retinaculum. To assess the difference between physical examination and ultrasound, statistical analyses were conducted on subgroups using a t-test. Additionally, PLT incidence was evaluated according to gender, ethnicity, and hand dominance.

Results

On ultrasound examination, the PLT was detected in 72.13% of wrists bilaterally (n = 88), 5.74% unilaterally (n = 7), and was absent in 22.13% of the 122 wrists examined (n = 27). Physical examination methods detected an average of 56.28% bilaterally (n = 68.66), 6.56% unilaterally (n = 8), and 37.16% as absent (n = 45.33). Total detection by ultrasound was 77.87% (n = 95), while the physical examination average was 62.84% (n = 76.66). Overall, there is a significant difference between the physical examination methods and ultrasonography in detecting PLT, with ultrasonography demonstrating greater accuracy. It should also be noted that the prevalence of PLT is not affected by gender.

Conclusion

Ultrasonography is crucial in clinical settings to confirm the presence of the PLT, even when a physical examination is inconclusive. Physical and ultrasound approaches can, therefore, be combined to avoid producing incorrect negative results when locating the PLT for tendon grafting.