Talo-Navicular and Calcaneo-Cuboid Fusion with PEEK H-pode TM vs. Titanium Maxlock TM Locking Plates: Comparison of Functional and Radiographic Outcomes.

BACKGROUND: Locking plates are increasingly used to achieve hindfoot fusion. The objective of this study was to compare hindfoot fusion outcomes with the PEEK H-podeTM (BiotechTM ) locking plate and the titanium MaxlockTM (Tornier-WrightTM ) locking plate.

HYPOTHESIS: A polyetheretherketone (PEEK) H-podeTM locking plate provides similar fusion rates to a titanium MaxlockTM locking plate for talo-navicular and calcaneo-cuboid arthrodesis.

METHODS: We conducted a retrospective comparative study in 39 patients (including 21 [54%] with pes planovalgus and 11 [28%] with neurological equinovarus deformities) who underwent talo-navicular and/or calcaneo-cuboid fusion, usually combined with subtalar fusion. The first 17 patients (January 2014-February 2016) were managed with MaxlockTM locking plates and the next 22 patients (March 2016-August 2018) with H-podeTM locking plates. These two cohorts of consecutive patients were comparable regarding age, sex distribution, body mass index, and comorbidities. At last follow-up more than 1 year after surgery, we compared functional scores, pain intensity, and fusion assessed by radiographs and computed tomography (CT) (threshold set at 33%).

RESULTS: Mean follow-up was 42 months (range, 34-63 months) in the MaxlockTM group and 25 months (range, 12-36 months) in the H-podeTM group. At last follow-up, the two groups were not significantly different for the mean values of the American Orthopedic Foot & Ankle Society score, European Foot & Ankle Society score, and visual analogue scale pain score. Neither were the two groups significantly different for talo-navicular and calcaneo-cuboid fusion by CT. In the MaxlockTM group, we found non-significant trends towards a higher proportion of patients with talo-navicular non-union (18% vs. 5% in the H-podeTM group) and weaker talo-navicular fusion in patients with pes planovalgus (60.8% vs. 82.0%, respectively). Radiographic results overestimated the fusion rates.

DISCUSSION: Talo-navicular and calcaneo-cuboid fusion was not significantly different with H-podeTM and MaxlockTM  locking plates. CT was more accurate than standard radiography to assess fusion. These results underline the usefulness of PEEK locking plates for talo-navicular and calcaneo-cuboid fusion; moreover, the radiolucency of PEEK facilitates the interpretation of radiographs.

LEVEL OF EVIDENCE: IV.