Biomechanical Evaluation of Spring Ligament Reconstruction with the Suture Tape or Tendon Graft in a Cadaveric Flatfoot Model

Research Type: Level 4 – Case series Introduction/Purpose: Adult-acquired flatfoot deformity (AAFD) can occur due to posterior tibialis tendon (PTT) degeneration and spring and deltoid ligament insufficiency. Some repair techniques reconstruct the spring ligament. A current repair technique involves suture-tape augmentation with anchors from the calcaneus to the navicular. We have developed a novel tendon graft reconstruction repair utilizing graft tissue from the medial talar neck to the navicular. The purpose of this study was to compare these two reconstruction methods in a cadaveric flatfoot model. Methods: Five matched-pair fresh-frozen cadaver feet (four female and one male, age 76.4±11.3 years) underwent flatfoot creation and reconstruction. The feet were cyclically loaded with 16,000 cycles from 200 N to 1.5× body weight at 1 Hz. Each foot was randomly assigned to undergo either suture-tape augmentation or tendon graft reconstruction. Radiographic parameters, foot motion, and pressure mapping were measured before loading, after loading, and after repair. Ramp-to-failure testing was conducted as well. Results: The cadaveric flatfoot model was successfully created, demonstrated by significant changes in Meary’s angle (mean change = 7.4°, < .05), talonavicular coverage (mean change = 14.7°, p < .05), and medial cuneiform height (mean change = 5.6mm, p < .05). The tendon graft technique (mean change = 7.1°, p < .05) resulted in more significant improvements in Meary’s angle compared to the other technique (mean change = 2.3°). There were no significant differences in inversion and eversion data between repair techniques. The tendon graft technique had a significantly higher failure threshold (mean failure = 2864.9 N, p< 0.05) compared to the other technique (mean failure = 2594.8N), and a lower failure rate (1/5 failed with tendon graft vs. 3/5 failed with suture tape). Conclusion: Both techniques successfully restored arch alignment and preserved hindfoot motion in a cadaveric flatfoot model. However, the tendon graft technique demonstrated greater improvement in alignment and failure resistance. Further evaluation of the tendon graft technique is necessary to determine its viability as a substitute for stabilizing procedures like osteotomies or fusions. Given the potential for host tissue incorporation, the tendon graft technique may offer better long-term durability. Foot Specimen Set Up for Loading Figure 1: (A) Lateral view of the foot with retro-reflective markers and of the Achilles tendon sandwiched between sailcloth. (B) Anterior view of the foot with retro-reflective markers.