Volar Plate Impingement Following Scaphoid Fracture Nonunion Surgery Using a Volar Locking Plate: A Retrospective Case Series.

Purpose: Internal fixation using volar locking plates is one surgical option for addressing scaphoid fracture nonunion. Concerns about impingement and plate removal remain, and there is limited literature on imaging findings. This study assessed volar plate impingement (VPI) using a classification based on radiographs and computed tomography (CT) scans.

Methods: A retrospective chart review was conducted on patients who underwent open reduction and internal fixation of scaphoid waist nonunion with a volar plate and bone grafting. Exclusions included less than 90 days of follow-up, lack of postoperative CT scans, or continued nonunion, which were excluded to eliminate further confounding variables in plate impingement. Three hand surgeons independently reviewed postoperative CT scans and radiographs, classifying VPI into four groups: none, mild (extra-articular wear), moderate (wear/bone loss involving the articular surface), and severe (plate blocking flexion and "spanning" the joint). These findings were correlated with plate removal.

Results: Twenty-one patients met the inclusion criteria. Computed tomography evaluation revealed five patients with no impingement, five mild, six moderate, and five severe. Only two patients exhibited impingement on X-ray evaluation. Eight patients (38%) underwent plate removal because of symptomatic impingement associated with pain or limited flexion. Three of five with severe impingement had plates removed, with one more planned for removal. Three of six with moderate impingement underwent plate removal. The impingement scale showed moderate inter-rater reliability.

Conclusions: The diagnosis of VPI based on CT scans is common after volar locked plating and occurs along a spectrum of findings ranging from minimal bony change to articular wear/block to motion. Radiographs are less sensitive to VPI and do not correlate with CT. Plate removal should be based on clinical symptoms, and a CT scan is more diagnostic than plain radiographs when evaluating for plate impingement.

Type of study/level of evidence: Level IV.