Radiographic Measurements of Pes Planovalgus Do Not Predict Clinical Outcomes in Tarsal Coalition Excision.

Objective: Many patients who undergo tarsal coalition excision have persistent postoperative pain. Most studies have utilized cat scan (CT) scan parameters of pes planovalgus and heel valgus but have found this to be an inconsistent predictor of outcomes. Plain radiographic parameters have been less utilized in trying to predict outcomes after coalition excision. Radiographic talonavicular coverage angle correlates with pain in patients with flexible pes planovalgus (PPV) but has not been studied in tarsal coalition population. Furthermore, foot alignment is not understood to change after simple coalition excision. The purpose of this study was to compare plain radiographic parameters, including talonavicular coverage angle, with pain after tarsal coalition excision, as well as compare preoperative and postoperative weight-bearing radiographs.

Methods: Seventy-seven feet that underwent excision of the tarsal coalition had clinical outcomes and radiographic data collected >1 year postoperatively. Measures of PPV on preoperative and postoperative weight-bearing radiographs and CT scans were evaluated.

Results: Patients were an average of 13 years old at excision. Of the total, 65% had calcaneonavicular (CN) coalitions, whereas the remainder had talocalcaneal coalitions. All patients had significant postoperative improvement in clinical outcomes but 34% (13/38) had continued pain at the most recent follow-up, more so in talocalcaneal than CN coalitions (55% vs 26%, P < 0.001). The subset with CN coalitions had more severe preoperative PPV but greater postoperative PPV improvement. Except for a weak correlation between radiographic weight-bearing (anterior-posterior) talus-first metatarsal angle and pain with activity (r = -0.54), there were no other correlations between preoperative radiographic parameters and clinical outcomes. Heel valgus on CT did not correlate with radiographic measurements of PPV or pain.

Conclusions: We did not find a correlation of radiographic PPV with persistent pain after tarsal coalition excision. We did find improvement in radiographic PPV in CN coalitions after treatment with simple excision. Heel valgus on CT was not a useful metric for evaluating PPV in the setting of a tarsal coalition.

Level of evidence: Level III-prognostic study.