High failure rates in comminuted patella fractures (AO/OTA 34-C3) fixed with an isolated new patella specific 2.7 mm variable angle locking plate.

Abstract

Objectives: To compare the outcomes of comminuted patella fractures fixed with a new patella-specific 2.7mm variable angle (VA) locking plate in isolation versus when augmentation of fracture fixation is applied with the plate.

Methods: Design:Retrospective.

Setting: Academic Level I Trauma Center.

Patient selection criteria: All acute comminuted patella fractures (AO/OTA 34-C3; complete displaced or undisplaced articular, frontal/coronal multifragmentary fractures) in adult patients primarily treated with a new patella-specific 2.7 mm VA locking plate (Synthes, Paoli, PA) between January 2021 and February 2024 at a single academic center were reviewed and divided in those fixed with the patella plate alone and those with additional bony and/or soft tissue augmentation. Excluded were those with < 90 follow-up, set a priori, unless complications occurred <90 days.

Outcome measures and comparisons: Comparison of patient age, sex, BMI, ASA, FRAX score, open fracture, polytrauma involvement, length of follow-up and post-operative protocols was made between groups. The primary outcome measure was loss of fixation. Secondary outcomes were mode of failure and other surgical complications.

Results: There were a total of 38 included patients, with no lack of or loss of follow-up, with 20 grouped into patella plate alone, and 18 into patella plate plus augmentation. The plate only group had a higher mean age (63.7 vs. 46.9, p=0.024), with no between-group differences in sex (65% vs. 44% female, p=0.20), BMI (p=0.51), 10-year fracture risk (FRAX) (p=0.06), open fractures (p=0.30), polytrauma involvement (p=0.97), or postoperative weight-bearing (p=0.76) or range of motion (p=0.06) protocols. There were eight failures (40.0%) in the plate-only group, and two failures in the plate with augmentation group (11.1%); (p=0.043). When controlling for known risk factors for osteoporosis and poor bone quality using the FRAX 10-year fracture risk on multivariable regression analysis, plate fixation with fracture augmentation was associated with a lower risk of fixation failure (OR=0.14, 95% CI 0.02-0.75; p=0.036). The plate-only group failed by loss of distal (62.5%, n=5) and proximal fixation (37.5%, n=3). Each of the two failures in the plate plus augmentation group had loss of distal fixation.

Conclusions: Treatment of comminuted patella fractures with a new patella-specific 2.7mm VA locking plate has a high failure rate when used in isolation. Augmenting fracture fixation with soft-tissue repair and/or independent fracture fragment fixation may significantly decrease failure rates. In particular, augmentation of the tendon avulsion component to restore the extensor mechanism appears critical.

Level of evidence: Therapeutic Level 3.