Sonography of the superomedial part of the spring ligament complex of the foot: a study of cadavers and asymptomatic volunteers.
ABSTRACT To evaluate the ability of high-resolution sonography for assessing the thickness and echogenicity of the superomedial part of the normal spring ligament in the foot in cadavers and asymptomatic volunteers.
The superomedial part of the normal spring ligament of four cadaveric feet was imaged with a high-resolution linear array transducer. Upon localization, the ligament was injected with 0.1% methylene blue with sonographic guidance. A posteromedial approach was used to dissect the feet immediately following injection to confirm accurate identification of the ligament. The bilateral ligaments in 40 asymptomatic adult volunteers were subsequently imaged.
Surgical dissection confirmed the accurate injection of methylene blue into all four cadaveric ligaments. The superomedial part of the normal spring ligament was identified bilaterally in all of the 40 asymptomatic volunteers, with a mean thickness of 3 mm in longitudinal short axes. The ligament was echogenic relative to surrounding fat, and it was thinner in women. Differences in ligament measurements with respect to age, sex, side (left vs. right) and foot dominance were not significant. The volunteers' height, weight and body mass index had a weakly positive correlation with ligament thickness.
High-resolution ultrasound can be used to identify and measure the thickness of the superomedial part of the normal spring ligament. The provided baseline measurements for the normal ligament could prove valuable when assessing the abnormal ligament.
- SourceAvailable from: stanford.edu
Conference Paper: Perturbation bounds for structured robust stability[Show abstract] [Hide abstract]
ABSTRACT: Structured robust stability involves large (but bounded) perturbations in certain loops of a multivariate system. That is, structured robust stability entails stability in the face of large, structured perturbations. The authors study the persistence under small, unstructured parametric perturbations of the robust stability (structured or unstructured) of a system. They derive parameter perturbation bounds which when repeated, ensure the robust stability of the perturbed modelsDecision and Control, 1988., Proceedings of the 27th IEEE Conference on; 01/1989
- [Show abstract] [Hide abstract]
ABSTRACT: We present nine cases of acquired flat foot deformity (AFFD) in adults caused by isolated spring ligament insufficiency. We present the clinical sign that allows differentiation of this diagnosis from posterior tibialis tendon (PTT) dysfunction namely the ability to single leg tiptoe, but with persistent forefoot abduction and heel valgus. In addition we illustrate the unique radiological features which allow confirmation of the diagnosis. Only a solitary previous case report has documented this alternative aetiology of AFFD; in that case, diagnosis was made intra-operatively. Six patients have been managed with orthoses. Three patients underwent surgery; one patient who presented early had isolated repair of the spring ligament complex. The remaining two required a calcaneal osteotomy and flexor digitorum longus transfer as for a PTT reconstruction. We propose that early diagnosis (with ultrasound confirmation) and management of this condition would offer a better prognosis and allow less interventional surgery.Foot and Ankle Surgery 02/2008; 14(2):89-95. DOI:10.1016/j.fas.2007.11.005
- [Show abstract] [Hide abstract]
ABSTRACT: This study was conducted to document the normal ultrasound anatomy of the spring ligament in asymptomatic subjects and to prospectively determine the frequency of ultrasound abnormality of the spring ligament in patients with suspected posterior tibial tendinopathy. The superomedial calcaneonavicular ligament (CNL) of 10 healthy volunteers was examined by ultrasound. Nineteen patients with a clinical diagnosis of suspected posterior tibial tendinopathy and/or chronic pain along the course of the tendon were examined by ultrasound. The superomedial CNL thickness was measured. Normal anatomy of the superomedial CNL could be demonstrated in all the volunteers. The mean of the combined proximal measurements was 4 mm and of the distal measurements 3.6 mm. Sixteen patients with posterior tibial tendinopathy had increased thickness of the spring ligament, which was more evident on its distal portion over the talar head. One patient had superomedial CNL insufficiency with normal posterior tibial tendon. The mean proximal measurement in the study group was 5.1 mm and the distal measurement 6.1 mm. The differences between the measurements in the study group and controls were highly significant (proximal site P < 0.01, distal site P < 0.001). Spring-ligament laxity or tear is characterised by thickening. There is a strong association between posterior tibial tendinopathy and abnormality of the spring ligament.European Radiology 11/2008; 18(11):2670-5. DOI:10.1007/s00330-008-1047-1 · 4.34 Impact Factor