Adult Acquired Flatfoot Deformity due to Spring Ligament Rupture Paul Butterworth, B.Pod, M.Pod, Carl Kihm, DPM and Craig Camasta, DPM, FACFAS Background Adult acquired flatfoot deformity (AAFD) may result from failure of osseous, ligamentous or tendonous structures that support the medial longitudinal arch. Failure of the posterior tibial tendon has traditionally been described as the main mechanism leading to AAFD (1-3). Recent literature suggests that disruption of the spring ligament complex can result in secondary strain on the posterior tibial tendon which it is unable to compensate for, subsequently resulting in its insufficiency (2, 4-6). Previous reports of spring ligament rupture without concomitant posterior tibial tendon pathology are sparse. The authors searched PubMed and CINAHL using the following search terms: spring ligament, calcaneonavicular ligament, posterior tibial tendon dysfunction and adult acquired flatfoot. The searches revealed four relevant studies (2, 4, 5, 7). None of these studies described using talonavicular and naviculocuneiform arthrodeses as the primary procedures of choice to correct the deformity, as the authors have done in this report. Case Report A forty year old female presented with chronic right foot pain and decreased function following a soccor injury at the age of sixteen. Medical treatment rendered at that time was cast immobilization for suspected fractures of multiple metatarsals, as reported by the patient. The patient attended for a podiatric surgical opinion 24 years later, complaining of severe pain on weightbearing which increased in severity throughout the course of the day. Non- steroidal anti-inflammatories provided minimal benefit when used sporadically. Clinical examination revealed a pes planovalgus foot type unilaterally with forefoot abductus indicated by a positive too many toes sign. The patient was unable to perform a single toe raise on the right side, arousing suspicion of posterior tibial tendon pathology. Gastrocnemius equinus was identified on the affected side with a positive Silfverskiold test. Talonavicular joint motion was excessive and induced pain and crepitus. Pain upon palpation and passive motion of the second and third metatarsocuneiform joints was also noted. Concomitant forefoot pathology included a mild hallux abducto valgus deformity and flexible claw toe deformities of the third, fourth and fifth digits. Pre-operative radiograph assessment was consistent with these clinical findings and the diagnosis of AAFD was made (figures 1 and 3). A curvilinear incision originating at the talonavicular joint and extending distally over the naviculocuneiform joints was utilized. Dissection was carried through the skin down to the subcutaneous tissues and deep fascia. Loose soft tissue was identified extending from the talonavicular capsule. The tissue was debrided in situ and appeared consistent with a full thickness tear of the superomedial component of the spring ligament (figure 5). Histopathological examination confirmed the intra-operative diagnosis. Surgical exploration revealed an intact posterior tibial tendon without pathological changes to its sheath (figure 5). Intra-operative talonavicular and naviculocuneiform joint instability was confirmed and arthrodeses of both joints was deemed necessary. Gastrocnemius aponeurosis recession from a medial approach served to alleviate the deforming ankle equinus force. Concomitant arthrodesis procedures of the second and third metatarsocuneiform joints were performed to address post-traumatic arthritic changes in these joints. The hallux abducto valgus deformity was corrected via a distal chevron osteotomy and lateral release. Flexor tenotomies of digits three through five addressed flexible deformities of these digits. Standard layered closure was performed for all incisions including re-approximation of the superomedial calcaneonavicular ligament. Restoration of the medial longitudinal arch was apparent on post-operative radiographs (figures 2 and 4). Discussion Misdiagnosis of spring ligament ruptures have been recognized in previous case reports (2, 4-5). Diagnosis preoperatively can be difficult due in part to unreliable diagnostic imaging techniques; which are often costly and do not alter treatment pathways (8). The spring ligament is poorly visualized on MRI due to its complex orientation which does not allow imaging in a single plane (8). The close relationship of the spring ligament with the posterior tibial tendon also makes it difficult to differentiate the two structures during clinical examination or by means of diagnostic imaging (8). Plain film radiographs allow the clinician to assess joint integrity and position but do not provide delineation between posterior tibial tendon and spring ligament pathology. Shibuya et al examined the relationship between posterior tibial tendon pathology and spring ligament rupture using radiographical measurements (9). These authors reported a direct correlation between end stage posterior tibial tendon dysfunction and spring ligament rupture (9). In addition, end stage posterior tibial tendon dysfunction demonstrated a statistically significant association with increased talar declination and Mearys angles (9). Following talonavicular and naviculocuneiform arthrodeses, our patient presented also showed significant improvements in both talar declination and Mearys angles (figures 1-4). However, arthrodesis of the second and third metatarsocuneiform joints may also have contributed to the stability of the midfoot and further aided in correction of these radiographical parameters. In the presence of spring ligament rupture, treatment options are varied and include primary ligament repair, tendon transfers or augmentation and bony realignment procedures of abnormal joints (2, 4-5, 10). Soft tissue procedures alone are not indicated in suspected cases of joint subluxation and deformity (11, 12). Stabilization of the talonavicular joint has been described previously for correction of symptomatic flatfoot (12-14). Primary arthrodesis of the talonavicular joint has been shown to provide a significant reduction in the total range of available motion in the subtalar and calcaneocuboid joints, making it a valuable procedure to reduce abnormal motion of the rearfoot (14-16). Naviculocuneiform arthrodesis has been recommended as an isolated procedure and in conjunction with talonavicular arthrodesis for the correction of AAFD (17-20). It may be used to balance a symptomatic flatfoot and to establish medial column stability and alignment (17). Conclusion Failure of the posterior tibial tendon is understood to result in collapse of the medial longitudinal arch as seen in AAFD; however, the role of the spring ligament complex is emphasized here. Surgeons should routinely inspect the integrity of the spring ligament and carefully consider its potential influence in the presence of joint instability and AAFD. References 1. Jennings MM, Christensen JC. The effects of sectioning the spring ligament on rear foot stability and posterior tibial tendon efficiency. Journal of foot and ankle surgery. 47(3): , Borton DC, Saxby TS. Tear of the plantar calcaneo-navicular (spring) ligament causing flatfoot a case report. Journal of bone and joint surgery (Br). 79-B (4): , Mann RA, Thompson FM. Rupture of the posterior tibial tendon causing flat foot. Journal of bone and joint surgery (Am). 67-A: , Tryfonidis M, Jackson W, Mansour R et al. Acquired adult flat foot due to isolated plantar calcaneonavicular (spring) ligament insufficiency with a normal tibialis posterior tendon. Journal of foot and ankle surgery. 14(2): 89-95, Shuen V, Prem H. Acquired unilateral pes planus in a child caused by a ruptured calcaneo-navicular (spring) ligament. Journal of pediatric orthopedics. 18(3): , Deland JT. The adult acquired flat foot and spring ligament complex: pathology and implications for treatment. Foot and ankle clinics. 6(1): , Mansour R, The J, Sharp RJ et al. Ultrasound assessment of the spring ligament complex. European Radiology. 18(11): , Rule J, Yao L, Seeger LL. Spring ligament of the ankle: Normal MR anatomy. American journal of radiology. 161: , Shibuya N, Ramanujam CL, Garcia GM. Association of tibialis tendon pathology with other radiographic findings in the foot: a case control study. Journal of foot and ankle surgery. 47(6): , Jacobs AM. Soft tissue procedures for the stabilization of medial arch pathology in the management of flexible flatfoot deformity. Clinics in podiatric medicine and surgery. 24(4): , Sitler DF, Bell SJ. Soft tissue procedures. Foot and ankle clinics. 8(3): , Mothershed RA, Stapp MD, Smith TF. Talonavicular arthrodesis for correction of posterior tibial tendon dysfunction. Clinics in podiatric medicine and surgery. 16(3): , Camasta CA, Menke CR, Hall PB. A review of 51 talonavicular joint arthrodeses for flexible pes valgus deformity. Journal of foot and ankle surgery. Abstract (Pubmed), PMID Weinheimer D. Talonavicular arthrodesis. Clinics in podiatric medicine and surgery. 21(2): , Rammelt S, Marti RK, Zwipp H. Arthodesis of the subtalar joint. Abstract (Pubmed), PMID Astion DJ, Deland JT, Otis JC et al. Motion of the hindfoot after simulated arthrodesis. Journal of bone and joint surgery (Am). 79-A (2): , Budny AM, Grossman JP. Naviculocuneiform arthrodesis. Clinics in podiatric medicine and surgery. 24(4):753-63, Cohen BE, Ogden F. Medial column procedures in the acquired flatfoot deformity. Foot and ankle clinics. 12(2):287-99, Greisberg J, Assal M, Hansen ST et al. Isolated medial column stabilization improves alignment in adult-acquired flatfoot. Clinics in orthopaedic related research. 435: , Ford LA, Hamilton GA. Naviculocuneiform arthrodesis. Clinics in podiatric medicine and surgery. 21(1): , Further Reading Domzalski M, Kwapisz A, Krol A et al. The role of the plantar calcaneonavicular ligament complex in the development of the adult flat foot: anatomical study. Abstract (Pubmed), PMID Taniguchi A, Tanaka Y, Takakura Y et al. Anatomy of the spring ligament. Journal of bone and joint surgery (Am). 85-A (11): , Sarrafian SK. Anatomy of the foot and ankle: descriptive, topographic, functional. Philadelphia: Lippincott; , Davis WH, Sobel M, Di Carlo EF et al. Gross, histological and microvascular anatomy and biomechanical testing of the spring ligament complex. Foot and ankle international. 17(2): , Bloome DM, Marymont JV, Varner KE. Variations on the insertion of the posterior tibialis tendon: a cadaveric study. Foot and ankle international. 24(10): , Patel V, Ebraheim NA, Frogameni A et al. Morphometric dimensions of the calcaneonavicular (spring) ligament. Foot and ankle international. 28(8): , Figures 1 and 2: Note the improvement in the dorsoplantar talocalcaneal and talar 1 st metatarsal angles postoperatively Figure 5: The small arrow indicates normal appearance of the posterior tibial tendon and the large arrow denotes a full thickness tear of the spring ligament (superomedial calcaneonavicular ligament). Figures 3 and 4: Postoperative improvement is noted in talar-1 st metatarsal angle (Mearys angle), talar declination and calcaneal inclination angle.