A Modified Palmar Approach With Tendon Splitting for Distal Phalanx Enchondromas of the Thumb: A Report of Two Cases

Abstract

Distal phalanx enchondromas of the thumb are rare and pose unique challenges for surgical management because of the thumb's critical role in hand function. Traditional dorsal and lateral approaches risk damaging extensor tendons, the nail matrix, limiting interphalangeal mobility, or compromising pinch function. This report presents two cases of thumb distal phalanx enchondromas successfully treated using a modified palmar approach with Bruner's incision followed by splitting the insertion of the flexor pollicis longus tendon. Both patients achieved complete curettage, bone regeneration, and full preservation of thumb function at the 1-year follow-up. The incision design avoided high-pressure zones of the pulp, reducing postoperative complications while maintaining functionality. Fluoroscopic guidance facilitated effective curettage through the flexor pollicis longus tendon split without extensive exposure. These findings underscore the tendon splitting palmar approach as a viable option in selected cases, highlighting the importance of individualized surgical strategies to optimize outcomes for distal thumb enchondromas.

Keywords: Distal phalanx; Enchondroma; Minimally invasive surgery; Palmar approach; Thumb.

Figure 1

Pre- and postoperative findings for case 1. A Left of the blue line: Preoperative radiographs, computed tomography, and magnetic resonance imaging (T1- and T2-weighted images), showing frontal (upper row), and sagittal (lower row) views. Right of the blue line: Postoperative radiographs at 1 week and 1 year, with frontal (upper row), and lateral (lower row) views. B Thumb range of motion at 1 year after surgery: extension (upper) and flexion (lower).

Figure 2

A Surgical procedure. (a) The incision (dotted blue line) began more than 20 mm proximal to the fingertip along the midline of the pulp. This incision extended approximately 10 mm from the proximal portion of the pulp to the outer edge of the interphalangeal crease, avoiding the central pulp (X). It was further connected to a Bruner’s incision, which extended approximately 5 mm proximally into the proximal phalanx. (b) A needle (blue cap) was inserted to confirm the level of the thumb interphalangeal joint and was used as a landmark to minimize disruption to subcutaneous tissue and fascia during dissection. (c) The insertion of the flexor pollicis longus tendon was longitudinally split, and the cortical bone was exposed using a custom-designed small retractor shaped from an omega-bent Kirschner wire (blue arrow). (d) A cortical window (yellow arrowhead, approximately 4 × 6 mm) was created using a fine scalpel blade. (e) Curettage was performed through the cortical window under fluoroscopic guidance using a small curved curette (red arrow). B (a) Frontal view of the fluoroscopic image during curettage. (b) Schematic illustration of curettage. Curettage was carefully performed through the cortical window (yellow) to avoid damaging the surrounding thinned cortical bone.

Figure 3

Pre- and postoperative findings for case 2. A Left of the blue line: initial radiographs, computed tomography, and postimmobilization radiographs at 2 months, showing frontal (upper row) and lateral (lower row) views. Right of the blue line: postoperative radiographs at 1 month and 1 year, showing frontal (upper row), and lateral (lower row) views. B Thumb range of motion at 1 year after surgery: extension (upper) and flexion (lower).