The Linburg-Comstock Anomaly: A Study on Prevalence and Effect on Various Strength Metrics

Abstract

Background: The Linburg-Comstock (LC) anomaly is a common tendinous connection between the flexor pollicis longus and flexor digitorum profundus (FDP), most frequently to the FDP of the index finger. The purpose of this study was to obtain epidemiologic data on the LC anomaly in a healthy, ethnically diverse population and to study the effect of the LC anomaly on grip strength, tip pinch strength, key pinch strength, and chuck pinch strength. Methods: We examined 500 healthy subjects (292 females and 208 males) bilaterally for the presence of the LC anomaly. Each subject had their grip strength, tip pinch strength, key pinch strength, and chuck pinch strength measured bilaterally using a dynamometer for grip strength and a pinch meter for all pinch strength measurements. Results: The LC anomaly was present in 213 of the 500 subjects (43%). One hundred one subjects (47%) had a unilateral presentation, and 112 (53%) subjects had a bilateral presentation. The LC anomaly was associated with a weaker tip pinch strength. When examining the LC anomaly among different ethnic groups, the highest prevalence was found in the Hispanic (57%) population followed by Caucasian (50%), Asian (41%), and African American (31%) populations. Conclusions: The LC anomaly has different prevalence according to ethnicity, with a higher prevalence in the Hispanic and Caucasian populations and a lower overall prevalence in the African American populations. The LC anomaly can also result in weaker tip pinch strength.