The Impact of Spring Ligament Injuries on Flatfoot Deformity: An Exploratory Study of Morphological and Radiographic...

Background: Spring ligament (SL) injuries are primarily associated with progressive collapsing flatfoot deformity, but can also occur due to trauma. It remains unclear whether the morphological changes following trauma differ from those caused by chronic overload. The aim of this study was (1) to analyze whether a relationship exists between the injury pattern and foot deformity and (2) to evaluate whether there is a distinction between trauma-related and non-trauma-related injuries. Method: We prospectively enrolled 198 patients with a median age of 57 years (range, 13 to 86 years; female, 127 (64%); male, 71 (36%)) who had a clinically diagnosed, surgically confirmed, and classified SL injury. We used weight-bearing standard X-rays to assess foot deformity. The control group consisted of 30 patients (median age 51 years, range, 44-66; female, 21 (70.0%); male, 9 (30.0%)) with no foot deformities or prior foot surgeries. Results: A 41.9% incidence of trauma was identified as the cause of these injuries, accounting for 16 (20.8%) of isolated injuries to the SL, 30 (42.9%) of SL injury accompanied by a posterior tibial (PT) tendon avulsion, and 37 (72.5%) of SL injury alongside a bony avulsion at the navicular injuries. The odds of being post-traumatic decreased with each year of age by a factor of 0.97 (95% CI: 0.95-0.99). Conclusions: While all radiographic measurements for flatfoot deformity became pathological after an injury to the SL, they did not accurately predict the injury patterns of the SL and distal PT tendon. Generally, post-traumatic cases exhibited lower severity of foot deformity, suggesting that other structures beyond the SL may contribute to the development of flatfoot deformity.