A Bitendinous Palmaris Longus: Aberrant Insertions and Its Clinical Impact - A Case Report

The Unpredictable Palmaris Longus Tendon Variation in Distal Radio-Ulnar Joint Reconstruction: A Technical Consideration for Undersized Graft

Background

Distal radioulnar joint (DRUJ) instability results from the disruption of the triangular fibrocartilaginous complex consisting of DRUJ’s primary and secondary stabilizers. The gold standard of stabilization procedure remains ligament reconstruction that utilizes tendon grafts to reanimate the volar and dorsal radioulnar ligament (RUL) as the primary stabilizers of the joint. The palmaris longus (PL) tendon, the graft of choice in reconstructive surgery, is commonly used in DRUJ reconstruction. However, it can exhibit anatomic variations from agenesis to the variation in morphology, location, and attachment that is rarely encountered other than in cadaveric studies.

Case Presentation

We present a case of a 14-year-old boy with ulnar-sided wrist pain and instability following an injury in a boxing match four months before admission. The clinical and radiological results suggested a DRUJ injury with extensor carpi ulnaris (ECU) tendinitis. A ligament reconstruction using the PL tendon graft was planned. Intraoperatively, the PL was found anomalous with dual distal attachments and a short graft length.

Results

We performed Adams ligament reconstruction technique with some modifications to the original design. To overcome the under-sized graft, instead of passing it around the ulnar neck, we added one more bone tunnel on the ulna to enhance the construct stability by a tendon to bone healing.

Conclusion

In reconstructive surgeries, surgeons should consider the other sources of grafts as graft variations exist. Otherwise, as in our case, modifications to the standard technique can be made.

Clinical Application of Anomalous Muscles for Tendon Transfer in the Upper Limb: A Systematic Review of the Literature

Numerous anomalous muscles of the forearm and hand have been reported in the literature. The majority were encountered in cadaver dissections and some were incidentally detected during tendon transfer surgery. Because of the limited number of motors available for transfer, it may be advantageous if an anomalous muscle with favorable anatomy can function as a potential donor in a suitable clinical environment. Although several authors have illustrated various anomalies and their functional significance, the reports of actual utilization of such muscles as donors for tendon reconstructions are sparse. The aim of the study is to conduct a systematic review of the clinical applications of anomalous muscles in the upper extremity. After a thorough search of PubMed, Web of Science, Scopus, and Cochrane Library databases, only three out of 106 studies were found to be relevant. Two of them discussed the anomalous radial wrist extensor tendon transfer for thumb flexion. The third study described the usage of anomalous flexor carpi ulnaris (FCU) for thumb opposition and index finger flexion, and also proposed a classification. This is the first systematic review of the clinical application of anomalous muscles as donors in the upper extremity tendon transfer surgical procedures. Knowledge of the above classification helps in intraoperative evaluation of the type of the anomaly and the possible consideration of anomalous muscle as a source of transplant material in an appropriate clinical setting.

Morphological variability of the palmaris longus muscle in human fetuses

Purpose

The palmaris longus (PL) muscle is characterized by high-morphological variability. It is clinically important as it is routinely harvested for the reconstruction of other tendons. The study characterizes the morphology of the PL in human fetuses and creates a new classification based on its variations that would relate to the spectrum of morphological variability in adults.

Methods

Eighty spontaneously aborted human foetuses (44 male, 36 female, 160 upper limbs), aged 18–38 weeks of gestation, were examined.

Results

The palmaris longus muscle was present in 62.5% of fetuses. The absence was bilateral in 26.25%, and unilateral in 22.5%. Nine types of palmaris longus muscles were identified based on the morphology of its insertion (Types I–IX). All types originated on the medial epicondyle of the humerus. The most common type was Type I, which was characterized by insertion to the palmar aponeurosis (52%). The rarest types were Type VII and Type IX (1% each). Type VII was characterized by partial doubling of the muscle belly, which then turned into two separate tendons that inserted together into the palmar aponeurosis. Type IX was characterized by fusion with the flexor carpi ulnaris muscle.

Conclusion

Our findings concerning morphological variability of the PL in fetuses present a new perspective on the understanding nature of the morphological variation of the PL muscle in adults.

List of evidence

Basic Science Study.

Anatomical variations of the palmaris longus muscle including its relation to the median nerve - a proposal for a new classification

BACKGROUND

The palmaris longus (PL) muscle is characterised by high morphological diversity, and its tendon crosses the median nerve (MN) at different levels. Due to the fact that the palmaris longus tendon is routinely harvested for reconstruction of other tendons, knowledge of its morphological variations is clinically important. Therefore, the purpose of the study was to suggest a new morphological classification of the PL muscle and characterise the relationship of its tendon to the median nerve.

METHODS

Standard dissection was performed on 80 randomised and isolated upper limbs (40 left and 40 right) fixed in a 10% formalin solution. Measurements of muscle belly and tendon were obtained. The course and location of tendon insertion, as well as its relationship to the median nerve, were noted.

RESULTS

The palmaris longus muscle was present in 92.5% of specimens. Three types of palmaris longus muscle were identified based on the morphology of its insertion (types I-III) and these were further subdivided into three subgroups (A-C) according to the ratio of the length of the muscle belly and its tendon. The most frequent was type I (78.8%), where the tendon attached to the palmar aponeurosis, and subtype B, where the tendon-to-belly ratio was 1-1.5 (41.1%). The mean distance from the interstyloid line to the crossing between the median nerve and the palmaris longus tendon was 31.6 mm. In addition, two types of palmaris longus were described.

CONCLUSION

The presented classification of palmaris longus muscle types allows a better characterization of its diversity and may be useful in planning tendon grafting.

A Case of Reverse Palmaris Longus Muscle- An Additional Muscle in the Anterior Compartment of the Forearm

It is uncommon to have additional muscles in the upper limb. Some of them may restrict the movements or compress the nerves and vessels, while others may go unnoticed. During the routine dissection for undergraduate medical students, we observed an additional muscle in the anterior compartment of the forearm in about 60-year-old male cadaver. The muscle had a prominent belly and a long tendon. Distally, it was attached to the flexor retinaculum by a short and thick tendon. Proximally, long tendon of the muscle passed between the flexor carpi ulnaris and palmaris longus and was attached to the common aponeurosis shared by the extensor carpi ulnaris and flexor digitorum profundus muscles. The additional muscle belly was supplied by a branch from the anterior interosseous nerve. The ulnar nerve and artery was passing deep to the fleshy belly of the muscle. The muscle reported here might compress the ulnar nerve and artery and may produce neurovascular symptoms. On the other hand, the tendon and fleshy belly of the muscle could be useful in muscle/tendon grafts. The observations made by us in the present case will supplement our knowledge of variations of the muscles in this region which could be useful for surgeons during the forearm and hand surgeries.