ACUTE SPRING LIGAMENT-COMPLEX TEAR

30 yr old male inversion injury some months ago with ongoing pain and progressive pes planus

MRI Ankle/Foot (Triplanar PD and PD fat-sat sequences):

  • Bone bruising med/plantar aspects talar head-neck; sustentaculum and anterior process calcaneus and lateral navicular (consistent with midfoot inversion injury).
  • High grade tear superomedial portion spring ligament and tibiospring component superficial deltoid ligament. MPO and IPL bands of the spring ligament thickened / scarred but intact.
  • Partial tearing of the cervical and interosseous talocalcaneal ligaments in the sinus tarsi.

 

spring1_1

PD SPAIR Sagittal – Talus, navicular and anterior calcaneal marrow oedema / bone bruising

spring2_2

(i) PD Coronal –Ruptured superomedial component Spring Lig

(ii) PD SPAIR Coronal  –Ruptured superomedial component Spring Lig (arrows at defect)

(iii) PD SPAIR Sagittal – SM portion Spring ligament tear cleft/rupture

 

Discussion

  • Calcaneonavicular ligament (Spring Ligament) complex is a key static stabilizer of the medial longitudinal arch and is frequently injured (often in association with posterior tibial tendon insufficiency).
  • Disruption of SL destabilizes longitudinal arch -> allowing plantar and medial rotation of talar head and valgus alignment of the calcaneus (pes planovalgus) – clinical result is an acquired flatfoot deformity.
  • Acute injuries of the spring ligament are rare (often athletes / trauma). Isolated tears of the spring ligament without associated PTT tear are very rare and can present as an acquired flatfoot deformity.
  • Surgical repair is now an important management component of adult-acquired flatfoot.
  • Toye et al (2005) correlated surgically proven SL tears with MRI findings: abnormal spring ligament calibre, signal intensity, waviness, full-thickness gap, and posterior tibial tendonopathy. The finding unique to cases with surgically proven tears is a full-thickness gap in the ligament, (79% of the 14 cases).

 

Anatomy

  • 3 bands of Spring:
    • Superomedial: medial surface of sustentaculum tali to navicular (most important for stability and most commonly injured component)
    • Medioplantar oblique: anterior margin of sustentaculum to navicular
    • Inferoplantar longitudinal: body of calcaneus to navicular

 

Imaging

  • MRI – PD and PD SPAIR imaging (tri-planar with thin sections)
  • CT – Torn ligament poorly defined (soft tissue windows)
  • XR – Flatfoot deformity may be evident

spring3_3

 

Differential Diagnoses

  • PTT tear / tendinopathy
  • Deltoid ligament sprain
  • Spring ligament recess
  • Navicular stress fracture (vague midfoot pain)

 

Further Reading:

  • Stadnick, ME. Spring Ligament Tear. MRI Web Clinic – January 2008
  • Toye LR, et al. MRI of Spring Ligament Tears. AJR 2005;184:1475-1480
  • Orr JD et al. Isolated spring ligament failure as a cause of adult-acquired flatfoot deformity. Foot Ankle Int. 2013: 34(6) 818-23
  • Stat Dx online (including graphic on current page)