Radiographic Correction of Stage III Posterior Tibial Tendon Dysfunction With a Modified Triple Arthrodesis

Abstract

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.