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

Abstract

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.

Keywords: DRUJ instability; anatomical variation; ligament reconstruction; palmaris longus; tendon graft.

Figure 1

(A) Bony prominence on the ulnar side of the left wrist. (B) Normal gap on the PA view wrist radiograph. (C) A radioulnar distance greater than 6 mm.

Figure 2

Magnetic Resonance Imaging. (A) Axial T1-weighted image revealed a lack of volar RUL, redundant extensor retinaculum, and flipped ECU sub-sheath that trapped between the ECU and the bony surface. (B) The axial T2 weighted image showed hyperintensity suggesting ECU tendinitis. (C) Coronal T2 images suggested an ulnar avulsion of the TFCC palmer 1B (dotted red circle). (Pink asterisk: dorsal RUL; yellow asterisk: ECU tendon; blue arrow: extensor retinaculum; red arrow: flipped ECU sub-sheath; green arrow: tendinitis).

Figure 3

(A) PL variation with a bitendinous portion at the distal attachment. The lateral division (LD) lies superficial to the flexor retinaculum (red dots) and the medial division (MD) lies under the flexor retinaculum. (B) The harvested 13-cm-long tendon.

Figure 4

(A) Dorsally, the whole fourth extensor compartment was retracted radially and subperiosteally. The radial tunnel is made by drilling the ulnar column of distal radius 5 mm radial to the DRUJ and 5 mm proximal to the radiocarpal joint. (B) At the palmar side, a longitudinal incision proximal to the wrist crease is made to harvest the tendon and pass the graft. (C) The volar limb of the graft is passed dorsally to be secured at the fovea interosseous tunnel.

Figure 5

(A) A longitudinal skin incision was made over the DRUJ. The EDM in the 5th compartment was retracted, then, an ulnarly-based flap of dorsal retinaculum is raised over the distal ulna, exposing the DRUJ capsule. In a hyperflexed wrist, a 3.5-mm bony tunnel was made from the fovea to the ulnar neck. (Black dot: Second ulnar tunnel) (B). The second ulnar interosseous tunnel (2.5 mm) is made proximally to pass one of the limbs. (Blue line: the first ulnar tunnel). (C and D) Both limbs are tied with the Pulvertaft weave technique.

Figure 6

An illustration of the intra articular RUL reconstruction technique using a PL graft. Both graft limbs are shown in different colors. (A) Dorsal view. (B) Radio-carpal view.