Prevalence of Absence of Palmaris Longus and Its Association with Gender, Hand Dominance and Absence of FDS Tendon to Little Finger Among Malay Population

Stabilization of the radial head with the palmaris longus or the gracilis tendon: an anatomical feasibility study

PURPOSE

The proximal radioulnar joint (PRUJ) and the radiocapitellar joint may be destabilized after trauma. Different techniques for stabilization of PRUJ have been proposed, but none of them can stabilize the radiocapitellar joint at the same time. We propose a ligamentoplasty to stabilize the radial head at these two joints by reconstructing the radial head annular ligament and the lateral collateral ulnar ligament (LCUL) with a single graft (palmaris longus or gracilis tendon of the knee).

METHODS

Fifteen cadaveric upper limbs were used to compare the stabilization obtained by performing our ligamentoplasty with the palmaris longus or the gracilis tendon. For each technique, the stabilization obtained was evaluated by measuring the displacement of the radial head in the anterior, lateral and posterior directions when a force of 1 N was applied in maximum supination, neutral rotation and maximum pronation. We also evaluated whether this technique could damage the ulnar nerve or the posterior interosseous nerve by dissecting them and whether it could limit the range of rotation of the forearm.

RESULTS

Our ligamentoplasty enables to restore PRUJ stability equivalent to the intact ligament condition. The palmaris longus was inconstant (13/15) and too short to allow concomitant reconstruction of the LCUL (except in one case). No nerve damage was found during the dissection, and the range of rotation of the forearm was not limited by the ligamentoplasty. We also report a clinical case with an excellent result and without complications.

CONCLUSION

This ligamentoplasty we have described makes it possible to stabilize the radial head with respect to the radial notch of the ulna and with respect to the capitellum of the humerus. The gracilis tendon is more suitable than the palmaris longus because of its constant presence and length. A clinical series is now necessary to better evaluate this technique.

A rare variation of intrinsic and extrinsic hand muscles represented by a bi-ventered first lumbrical extending into the carpal tunnel combined with bilateral fifth superficial flexor digitorum tendon regression

A rare unilateral variation of the first left lumbrical muscle was discovered in a female Caucasian cadaver dissected during a first year anatomy course at the Paracelsus Medical University - Nuremberg, Germany. The muscle possessed two venters with the first originating near the medial epicondyle of the humerus together with the intramuscular tendon of the superficial flexor digitorum tendon, and the second presenting as a regular first lumbrical muscle with radial palmar origin from first tendon of the deep flexor digitorum muscle. Both muscle bellies were connected by a 1.42mm thick tendon that passed beneath the median nerve and ran through the carpal tunnel. The second belly was enlarged and entered the distal part of the carpal tunnel. Interestingly, the donor revealed further rare variations such as a bilateral regression of the fifth superficial flexor tendons to an obviously non functional connective tissue strand, lack of both palmaris longus muscles, a discoid lateral meniscus in the left knee, and reduction of the plantaris muscle to a fascia-like structure on the right leg. Lumbrical muscle variations extending into the carpal tunnel, especially those associated with auxiliary tendons, have significant clinical relevance due to their association with carpal tunnel syndrome.