Radiographic correction of stage III posterior tibial tendon dysfunction with a modified triple arthrodesis

Background: The literature supports fusion as the surgical treatment of choice for stage III posterior tibial tendon dysfunction (PTTD). The present study reports the radiographic correction following a modified triple arthrodesis (fusions of the subtalar, talonavicular, and first tarsometatarsal joints) in patients with stage III PTTD.

Methods: An institutional review board-approved retrospective study was performed to assess the radiographic outcome of a modified triple arthrodesis in 21 patients (22 feet). Pre- and postoperative weight-bearing radiographs were reviewed in a blinded fashion by clinicians of varying levels of training. The talo-first metatarsal, talocalcaneal, and talonavicular coverage angles were measured on anteroposterior views. On lateral views, the talo-first metatarsal (Meary's), talocalcaneal, calcaneal pitch, and talar declination angles and the medial cuneiform to floor distance were measured. Statistical analysis was performed to compare pre- and postoperative measurements, assess the degree of correction, and determine interobserver reliability of the radiographic measurements.

Results: All measurements improved significantly after treatment with a modified triple arthrodesis (P ≤ .001). The medial cuneiform to floor distance (0.910), talonavicular coverage angle (0.896), and lateral talo-first metatarsal angle (0.873) were the most reproducible between observers. Postoperatively, 100% of feet were corrected to normal medial cuneiform to floor distance and talonavicular coverage angle, and 90.9% were corrected to a normal lateral talo-first metatarsal angle.

Conclusion: The modified triple arthrodesis resulted in a reliable and reproducible correction of the deformity seen in rigid stage III PTTD.

Level of evidence: Level IV, case series.