Influence of Talar and Calcaneal Morphology on Subtalar Kinematics During Walking.

BACKGROUND: Cadaver biomechanical testing suggests that the morphology of articulating bones contributes to the stability of the joints and determines their kinematics; however, there are no studies examining the correlation between bone morphology and kinematics of the subtalar joint. The purpose of this study was to investigate the influence of talar and calcaneal morphology on subtalar kinematics during walking in healthy individuals. METHODS: Forty ankles (20 healthy subjects, 10 women/10 men) were included. Participants walked at a self-selected pace while synchronized biplane radiographs of the hindfoot were acquired at 100 images per second during stance. Motion of the talus and calcaneus was tracked using a validated volumetric model-based tracking process, and subtalar kinematics were calculated. Talar and calcaneal morphology were evaluated using statistical shape modeling. Pearson correlation coefficients were used to assess the relationship between subtalar kinematics and the morphology features of the talus and calcaneus. RESULTS: This study found that a shallower posterior facet of the talus was correlated with the subtalar joint being in more dorsiflexion, more inversion, and more internal rotation, and higher curvature in the posterior facet was correlated with more inversion and eversion range of motion during stance. In the calcaneus, a gentler slope of the middle facet was correlated with greater subtalar inversion. CONCLUSION: The morphology of the posterior facet of the talus was found to a primary factor driving multiplanar subtalar joint kinematics during the stance phase of gait. CLINICAL RELEVANCE: This new knowledge relating form and function in the hindfoot may assist in identifying individuals susceptible to subtalar instability and in improving implant design to achieve desired kinematics after surgery.

The Influence of Radiograph Obliquity on Böhler's and Gissane's Angles in Calcanei.

In calcaneal fractures, Böhler's and Gissane's angles are considered important parameters to guide treatment strategy and provide prognostic information during follow-up visits. Therefore, lateral radiographs have to be accurate. The aim of this study was to evaluate the effect of craniocaudal and posteroanterior angular variations (i.e., simulate lower leg malposition) from the true lateral radiograph on Böhler's and Gissane's angles. In this radioanatomical study, 15 embalmed, skeletally mature, human anatomic lower limb specimens were used. Using predefined criteria, a true lateral radiograph (i.e., 0° angular variation) was obtained. Angular variations from this true lateral radiograph were made from -30° to +30° deviation in the craniocaudal and posteroanterior direction at 5° intervals. Böhler's and Gissane angles were independently assessed by 2 experienced trauma surgeons. Böhler's angle decreased with increasing caudal angular variations (maximum -4.3° deviation at -30°). With increasing of the posterior angular variations, Böhler's angle increased (maximum 5.0° deviation at +30°) from the true lateral radiograph, but all deviations were within the measurement error. The deviation of the angle of Gissane was most pronounced in the cranial direction, with the mean angle decreasing by -8.8° at +30° angular variation. Varying angular obliquity in the caudal and posteroanterior direction hardly affected Gissane's angle. Foot malpositioning during the making of a lateral radiograph has little influence on Böhler's and Gissane's angles. If used for clinical decision-making in initial treatment and during follow-up of calcaneal fractures, these parameters can reliably be obtained from any lateral radiograph.

Morphometric measurement and types of articular facets on the talus and calcaneus in an Anatolian population / Mediciones morfométricas y tipos de facetas articulares en el talus y calcáneo de una población Anatolia

Anatomical variations in terms of ligamentous attachments, articulations and bony morphology are common in the subtalar region. The shape of the articular facets of the talus and calcaneus and their relationship to each other are important for joint function and surgical procedures. In this study an assessment of the morphology of the articular facets of the talus and calcaneus, in an Anatolian population, was undertaken. 49 tali and 57 calcanei from Anatolian adults of unknown gender were examined. The types of articular facets on the talus and calcaneus were determined using the following classification: Type A1, the distance between the anterior and middle facets was less than 2 mm; Type A2, the distance between the anterior and middle facets was 2-5 mm; Type A3, the distance between the anterior and middle facets was more than 5 mm; Type A4, there was only one articular facet; Type B1, the separation between the anterior and middle facets was not complete; Type B2, separation of the anterior and middle facets was present; Type C, no separation between the anterior, middle and posterior facets was present, i.e. there was one articular facet. In addition, the anteroposterior length and width of the talus and calcaneus, together with the width, length and depth of sulcus tali and sulcus calcanei were determined. Left and right tali, respectively, displayed the folowing types of articular facet: A1, 0 %, 0 %; A2, 0 %, 3,4 %; A3, 0 %, 0 %; A4, 0 %, 0 %; B1, 60 %, 51,8 %; and B2, 40 %, 44.8 %. Articular facets on left and right calcanei, respectively, were: A1, 10 %, 7.4 %; A2, 10 %, 14.8 %; A3, 16.7 %, 11.1 %; A4, 3.3 %, 3.7 %; B1, 30 %, 22.2 %; B2, 30 %, 40.8 %. The length and width of left and right tali were 50.5±3.81 mm and 39.5±2.97 mm, and 53.1±4.38 mm and 39.3±3.66 mm, respectively. The width, length and depth of left and right sulcus tali were: 5.2±1.09 mm, 21.7±2.73 mm and 5.7±0.84 mm, and 6.1±2.05 mm, 21.1±3.66 mm and 5.7±1.52 mm, respectively. For left and right calcanei length and width were; 76.1±5.44 mm 44.0±3.97 mm, and 75.7±6.76 mm and 45.9±4.21 mm, respectively. The width, length and depth of left and right sulcus calcanei were: 6.4±1.19 mm, 31.9±2.76 mm and 4.0±0.81 mm, and 5.5±1.00 mm, 32.4±3.23 mm and 4.4±1.05 mm, respectively. The articular facets on both the talus and calcaneus in the Anatolian population studied was predominantly type B. This observations is similar to previous reports conducted in America, India and Africa, but differ from those undertaken in Europe. A knowledge of variations of the articular facets of the talus and calcaneus provides a valuable road map for orthopaedic surgeons, as well as others involved in foot rehabilitation.

Las variaciones anatómicas de ligamentos, articulaciones y morfología ósea son comunes en la región subtalar. La forma de las facetas articulares del talus y calcáneo y su relación mutua son importantes para la función articular y los procedimientos quirúrgicos. En este estudio se realizó una evaluación de la morfología de las facetas articulares del talus y del calcáneo en una población de Anatolia. Se examinaron 49 talus y 57 calcáneos de individuos adultos anatolios de sexo no conocido. Se clasificaron las facetas articulares del talus y el calcáneo de la siguiente manera: Tipo A1, la distancia entre las facetas anterior y media fue inferior a 2 mm; Tipo A2, la distancia entre las facetas anterior y media fue de 2-5 mm; Tipo A3, la distancia entre las facetas anterior y media fue de más de 5 mm; Tipo A4, sólo había una faceta articular; Tipo B1, la separación entre las facetas anterior y media no fue completa; Tipo B2, la separación de las facetas anterior y media estaba presente; Tipo C, no existía separación entre las facetas anterior, media y posterior, es decir, había una faceta articular. Además, se determinó la longitud anteroposterior y el ancho del talus y del calcáneo, junto con el ancho, la longitud y la profundidad del surco talar y del surco del calcáneo. Los talus izquierdo y derecho, respectivamente, mostraron los siguientes tipos de faceta articular: A1, 0 %, 0 %; A2, 0 %, 3,4 %; A3, 0 %, 0 %; A4, 0 %, 0 %; B1, 60 %, 51,8 %; B2, 40 %, 44,8 %. Las facetas articulares de los calcáneos izquierdo y derecho, respectivamente, fueron: A1, 10 %, 7,4 %; A2, 10 %, 14,8 %; A3, 16,7 %, 11,1 %; A4, 3,3 %, 3,7 %; B1, 30 %, 22,2 %; B2, 30 %, 40,8 %. La longitud y el ancho de talus izquierdo y derecho fueron 50,5±3,81 mm y 39,5±2,97 mm, y 53,1±4,38 mm y 39,3±3,66 mm, respectivamente. El ancho, la longitud y la profundidad del surco talar izquierdo y derecho fueron: 5,2±1,09 mm, 21,7 ± 2,73 mm y 5,7±0,84 mm, y 6,1±2,05 mm, 21,1±3,66 mm y 5,7±1,52 mm, respectivamente. Para el calcáneo izquierdo y derecho, la longitud y ancho fueron: 76,1±5,44 mm 44,0±3,97 mm y 75,7±6,76 mm y 45,9±4,21 mm, respectivamente. El ancho, longitud y profundidad del surco del calcáneo izquierdo y derecho fueron: 6,4±1,19 mm, 31,9±2,76 mm y 4,0±0,81 mm, y 5,5±1,00 mm, 32,4±3,23 mm y 4,4±1,05 mm, respectivamente. Las facetas articulares, tanto en el talus como en el calcáneo en la población de Anatolia estudiada, eran predominantemente de tipo B. Estas observaciones son similares a reportes previos realizados en América, India y África, pero difieren de los realizados en Europa. Un conocimiento de las variaciones de las facetas articulares del talus y del calcáneo proporciona una valiosa hoja de ruta para los cirujanos ortopédicos, así como otros involucrados en la rehabilitación de los pies.

Quantification of Subtalar Posterior Facet Involvement During Intramedullary Guidance of Total Ankle Arthroplasty:A Cadaveric Study.

Total ankle arthroplasty is an evolving treatment of ankle arthritis. One implant uses intramedullary guidance to enhance accuracy by accessing the tibial canal through the inferior aspect of the foot, potentially placing the subtalar joint articulation at risk. The purpose of the present cadaveric anatomic evaluation was to identify posterior subtalar articular facet joint involvement during intramedullary guidance to the tibial canal. Ten below-the-knee cadaveric specimens were used. After drilling into the tibial medullary canal with a 6-mm drill bit and using the standard targeting jig, the specimens were dissected, and the posterior facet was evaluated. We graded posterior facet involvement according to the location of the drill hole and, if within the facet, the percentage of the facet violated by the drill bit, with 100% representing the full circumference of the 6-mm drill bit. Of the 8 specimens in which the drill bit passed through the subtalar posterior articular facet, the encroachment was peripheral in all cases, with no specimen showing circumferential 6-mm drill bit articular penetration (no cases with 100%). Sinus tarsi penetration occurred in 20% of the cases. The dissections with articular involvement included 3 specimens with >50% of the drill bit penetrating and 5 with <50%. The portion of the posterior facet involved among the specimens that were violated was anterocentral in the joint. A risk of damage to the posterior facet of the subtalar joint exists with intramedullary total ankle systems. Our study has demonstrated that the drill bit will involve the anterocentral and anterolateral portions of the posterior facet of the subtalar joint, with <6 mm articular disruption in all cases.

Evans osteotomy and risk to subtalar joint articular facets and sustentaculum tali: a cadaver study.

The Evans lateral column lengthening procedure allows correction of abduction, improved talar head coverage, decreased forefoot and rearfoot valgus, and improvement of medial column arch height. However, identifying the structures at risk when performing this osteotomy has proved difficult in vivo. Using 10 cadaveric lower limbs, we performed the Evans calcaneal osteotomy and determined whether violation of the calcaneal facets and the sustentaculum tali occurred. Based on our findings, we recommend directing the osteotomy from posterolateral to anteromedial.

Predictive factors for residual equinovarus deformity following Ponseti treatment and percutaneous Achilles tenotomy for idiopathic clubfoot: a retrospective review of 50 cases followed for median 2 years.

BACKGROUND AND PURPOSE: There is no consensus on how to predict residual equinovarus deformities after application of the Ponseti method. We assessed the prognostic value of clinical scoring systems, and also radiographic parameters that can be measured just before percutaneous Achilles tenotomy (PAT). METHOD: We reviewed 50 cases of clubfoot in 35 patients who were treated using the Ponseti method, including PAT, to analyze the factors that are predictive of residual equinovarus deformities. Mean age at the time of PAT was 2.4 (1.4-3.5) months, and the mean follow-up period was 23 (9-61) months. We divided these cases into 2 groups according to the need for further surgery to treat the residual deformities. RESULTS: 40 feet with satisfactory results were included in group 1, whereas the remaining 10 feet that required further surgery for unsatisfactory residual deformities were included in group 2. We compared the initial Dimeglio and Pirani scores obtained before the first Ponseti casting, follow-up Pirani scores, and radiographic parameters determined just before PAT between these 2 groups. There was no statistically significant difference between the groups in terms of the initial Dimeglio and Pirani scores, although the follow-up Pirani scores and lateral tibiocalcaneal angle were higher and the lateral talocalcaneal angle was lower in group 2 at the time of PAT. INTERPRETATION: We conclude that the Pirani score, lateral tibiocalcaneal angle, and talocalcaneal angle, when assessed immediately before PAT, might be predictive factors for residual equinovarus deformity following Ponseti treatment for severe idiopathic clubfoot.

Subtalar joint arthrodesis.

Isolated subtalar joint arthrodesis has gained popularity more recently. Research has shown that it preserves rearfoot motion, does not increase the risk of arthritis in adjacent joints, and is not an especially complex operative procedure. It decreases the chance of midtarsal joint nonunion and malunion postoperatively. This article takes an in-depth approach to isolated talocalcaneal fusions. Anatomy and biomechanics of the subtalar joint are reviewed. Clinical presentation and radiologic evaluation are discussed. Conservative treatment, operative technique, and postoperative management are included.

Artroscopía de la articulación subastragalina: técnica quirúrgica, indicaciones, resultados y complicaciones / Subtalar joint arthroscopy: surgical technique, indications, results and complications

Introducción: El abordaje artroscópico para el tratamiento de la patología subastragalina se encuentra en pleno desarrollo. El propósito del presente trabajo es efectuar una descripción de las indicaciones, técnica quirúrgica, resultados y complicaciones en la realización de la artroscopía de la articulación subastragalina. Material y método: Se presenta 14 pacientes con patología de la articulación subastragalina, tratados durante los años 2003 al 2009. Se realizaron 11 artroscopías posteriores y 3 laterales. Seguimiento: 36 meses (R=15-69). Todos los pacientes fueron evaluados mediante el score AOFAS y a los 12 meses de la cirugía se les pregunto: 1- Si estaban satisfechos con el resultado de la cirugía. 2- Si volverían a realizar la intervención. Resultados: La indicación más frecuente de artroscopía para la articulación subastragalina ha sido en nuestra casuística la artrosis (35,71 por ciento). El score AOFAS promedio fue de 88,42 (R=46-100). El 78,58 por ciento de los pacientes estaban satisfechos con el resultado del procedimiento y un 85,72 por ciento volvería a operarse. Tuvimos una complicación de un paciente con hipoestesia del talón (7,14 por ciento). Conclusiones: La artroscopía de la articulación subastragalina es una herramienta diagnóstica y terapéutica segura, reproducible y confiable, exige un conocimiento de la anatomía artroscópica de la región y debe ser llevada a cabo por artroscopistas con experiencia. Diseño del estudio: Serie de casos. Nivel de evidencia: IV.

Portal safety and efficacy of anterior subtalar arthroscopy: a cadaveric study.

Anterior subtalar arthroscopy was performed in 14 feet of 7 cadaveric bodies using the primary visualization and working portals. The cartilage of the anterior/middle calcaneal facet that can be reached was marked. The feet were dissected and the distances between the portals and surrounding cutaneous nerves were measured. Any damage to the ligaments of the sinus tarsi was noted. The percentage area of the articular cartilage that was marked was measured. In all specimens, the primary visualization portal tract passed through the lateral root of the inferior extensor retinaculum. The primary working portal tract passed through the lateral root in nine specimens (64%). Cervical ligament was intact in all specimens. In three specimens (21%), the primary visualization portal tract passed through the posterior edge of the intermediate root of the inferior extensor retinaculum. The interosseous talocalcaneal ligament was intact in all specimens. The primary visualization portal tract passed through the medial root of the inferior extensor retinaculum in eight specimens (57%). The primary working portal tract passed through the medial root of the inferior extensor retinaculum in one specimen. The average working area on the calcaneal facet was 95% +/- 4% of the total articular surface. There was no case of nerve injury in all specimens. In conclusion, anterior subtalar arthroscopy is a minimally invasive approach to deal with pathologies of this joint without the need of extensive resection of the ligamentous structures of the sinus tarsi.

Comparação de protocolos para determinação do ângulo de pronação subtalar / Comparison of protocols for determining the subtalar joint angle

INTRODUÇÃO: Muitos estudos têm analisado a máxima pronação subtalar sem preocupações na escolha do modelo de determinação dessa variável. OBJETIVO: Comparar a máxima pronação subtalar e o seu momento de ocorrência durante a fase de suporte, determinados a partir de dois modelos matemáticos compostos de dois e quatro pontos de referência, respectivamente. METODOLOGIA: Dezesseis corredores participaram de dois testes de economia de corrida em esteira rolante, nas velocidades de 16 e 17 km.h-1. RESULTADOS: Houveram diferenças significativas no consumo de oxigênio entre as velocidades adotadas, contrário aos valores de máxima pronação subtalar e de seus momentos de ocorrência que não apresentaram diferenças significativas entre as velocidades, independente do modelo matemático adotado. Comparando-se os dois modelos matemáticos, os valores de máxima pronação subtalar apresentaram diferenças significativas, independentemente da velocidade. Em contrapartida, os momentos de ocorrências da máxima pronação subtalar não apresentaram diferenças significativas. CONCLUSÃO: A medida da máxima pronação subtalar é influenciada pelo modelo matemático adotado. Entretanto, o momento de ocorrência da máxima pronação subtalar ao longo da fase de suporte independe do modelo.

INTRODUCTION: Many studies have analyzed the maximum subtalar pronation without any concern over the choice of model for determining this variable. OBJECTIVE: To compare the maximum subtalar pronation and its moment of occurrence during the stance phase, determined based on two mathematical models consisting of two and four reference points, respectively. METHOD: Sixteen runners participated in two running economy tests on a treadmill at speeds of 16 and 17 km.h-1. RESULT: The study showed significant differences in oxygen consumption between the speeds adopted, contrary to the values of maximum subtalar pronation and their moments of occurrence, which did not show any significant differences between the speeds, regardless of the mathematical model adopted. Comparing the two mathematical models, the values of maximum subtalar pronation showed significant differences, regardless of speed. However, the moments of occurrence of maximum subtalar pronation showed no significant differences. CONCLUSION: The measure of maximum subtalar pronation is influenced by the mathematical model adopted. However, the moment of occurrence of maximum subtalar pronation during the stance phase is independent of the model.

The distance between the sural nerve and ideal portal placements in lateral subtalar arthroscopy: a cadaveric study.

BACKGROUND: There have been limited studies assessing the relative safety of lateral portals for subtalar arthroscopy in terms of their distance from the sural nerve and its branches. The aim of this cadaveric study was to assess and compare the distance of lateral subtalar arthroscopy portal sites to the sural nerve and its branches. MATERIALS AND METHODS: Twenty embalmed cadaveric lower limbs were dissected exposing the nerves and tendons and subtalar arthroscopy portals were replicated using pins. The anatomically important distances were measured with a digital caliper. Statistical analysis of the data was performed using SPSS for Windows 11.5 (SPSS Inc, Chicago, IL) using Friedman Tests and Wilcoxon Signed Ranks tests. RESULTS: The median distance of the anterior and middle subtalar portals to the nearest nerve was 21.3 mm and 20.9 mm, respectively, and 11.4 mm for the posterior portal. There was no statistically significant difference between anterior and middle portals (p=0.87) but there was statistically significant difference between anterior versus posterior and middle versus posterior portals (p=0.001 in each comparison). CONCLUSION: The anterior and middle subtalar portals were both less likely to damage important structures than the posterior subtalar portal. CLINICAL RELEVANCE: The results of this study can be of value to the surgeon when planning arthroscopic procedures to the subtalar joint from the lateral approach.

The posterior talofibular ligament: an anatomical study with clinical implication in clubfoot surgery.

BACKGROUND: The role of the posterior talofibular ligament (PTFL) in the clubfoot deformity remains unclear. We conducted an anatomical study to precise its topography and role in maintaining tibiotalar equinus in patients with clubfoot deformity. METHODS: Ten ankles were dissected using a wide posterior exposure. The PTFL was identified at the posterior aspect of the ankle and its relations with other anatomical structures were noted. RESULTS: After opening of the tibiotalar and subtalar joints, the superior aspect of the PTFL was clearly seen, running horizontally from the fibula to a prominent tubercle on the posterior surface of the talus. The tibiotalar and subatalar joint capsules joined together laterally on the posterior edge of the PTFL and medially on the posterior part of the talus. A fibrous structure identified as being the "tibial slip" was noted in four cases between the posterior medial aspect of the lateral malleolus and the tibiotalar posterior capsule. Two different groups of fibers were identified inside the PTFL. CONCLUSIONS: Correcting the equinus and inversion of the talus needed an extensive release of soft tissues of the posterior part of the ankle. Our description of both short anterior and long posterior fibers of the PTFL improved our comprehension of functional anatomy of this ligament. We have found that PTFL is part of a posterior joint complex between the tibiotalar and subtalar joint. The posterior joint complex is a heritage of ankle evolution from a prehensile to a weight-bearing joint pattern. The inferior tibiofibular transverse ligament, the tibial slip and the calcaneofibular ligament are interpreted as derivatives of this ancestral meniscus and stabilize the weight-bearing ankle. Because the posterior fibers of the PTFL and the tibial slip are part of the complex, they should be excised like the posterior capsules during clubfoot surgery.

Arthroscopic visualization of the posterior subtalar joint in the prone position: a cadaver study.

PURPOSE: Subtalar arthroscopy in the prone position is thought to allow broader access to the posterior aspect of the joint than in the standard supine or lateral position. This study is aimed to assess if using the posteromedial (PM) portal in the prone position can increase the working area available through the dorsal and ventral posterolateral (PL) portals commonly used in the standard techniques. TYPE OF STUDY: In vitro cadaver study. METHODS: Six below-knee cadaver specimens were subjected to experimental arthroscopy on the posterior subtalar joint in a simulated prone position. On both the talar and calcaneal surfaces, the working areas (the maximal extent available to a working instrument while preserving surrounding cartilage) for the PL portals and the PM portal were identified. The combined area was compared with the area available from the PL portals alone, to assess the area extended with the PM portal. RESULTS: The talar working areas provided by the PL portals and PM portal were 31% +/- 13% and 26% +/- 8% of the total articular surface, respectively. The combined working area (43% +/- 13%) was greater than the PL working area alone; use of the PM portal increased the working area by a factor of 1.45. The calcaneal working areas from the PL and PM portals were 25% +/- 11% and 20 +/- 7%, respectively. The combined working area (35% +/- 14%) was similarly increased by a factor of 1.46 using the PM portal compared with PL portals alone (P < .05). CONCLUSIONS: In prone subtalar arthroscopy, significant extension of the working area was found by adding the PM portal to the standard PL portals, on both the talar and calcaneal surfaces. CLINICAL RELEVANCE: The PM portal that can be used in the prone position has a potential to increase the arthroscopic working area in the posterior subtalar joint.

Resection for symptomatic talocalcaneal coalition.

Over a 10-year period, 20 persistently symptomatic talocalcaneal tarsal coalitions were treated with resection. These cases were reviewed at an average of 29 months after treatment. Preoperative computed tomography (CT) scans were obtained in 17 of 20 feet. Good or excellent clinical results were obtained in 77% of patients with resection of coalitions involving one third or less of the total joint surface. Increasing age in this group was not a contraindication to surgery. Four patients had an uncommon varus deformity and were treated with resection. Overall this subgroup had a poorer prognosis.

Tarsal coalition.

Tarsal coalition is a bridging between the tarsal bones of the foot. The bridge may be composed of bone, cartilage, fibrous tissue, or a combination of these. When symptomatic, patients usually present with hindfoot pain and frequent sprains as children, adolescents, or young adults. The classical appearance is a rigid flatfoot with heel valgus and abduction of the forefoot. Flexible cavus feet have been reported. The incidence in the general population is less than 1%, and the most common types are talocalcaneal and calcaneonavicular coalitions. The cause is attributed to failure of segmentation and differentiation of the primitive mesenchyme. Calcaneonavicular coalitions can be diagnosed with an oblique radiograph of the hindfoot. Most talocalcaneal coalitions require computerized tomography for diagnostic confirmation. Magnetic resonance Imaging may be useful for cartilaginous and fibrous coalitions. Casting is the usual initial treatment for the symptomatic individual. With treatment failure, in the absence of degenerative changes, resection of the coalition can be performed with good results. Isolated subtalar fusion may be performed for failed talocalcaneal resections. Failed subtalar fusions and failed calcaneonavicular resection may be treated with triple arthrodesis.

Anatomic structures at risk: combined subtalar and ankle arthrodesis with a retrograde intramedullary rod.

Retrograde intramedullary rodding from the calcaneus, through the talus, and into the tibia is currently an evolving procedure being used for salvage of severe foot/ankle deformity, arthritis, tumor, and instability. In this study, retrograde rodding was performed on six cadaver specimens. The specimens were then dissected to determine the subcalcaneal structures at risk and the optimal insertion point for the rod. This study elucidated the structures most at risk and showed the optimal insertion site to be at the junction of the sustentaculum tali and the body of the calcaneus.

Arthroscopy of the subtalar joint: establishing a medial portal.

One of the recently introduced procedures for studying the posterior subtalar joint is subtalar arthroscopy. There is no reference in the literature to the possibility of a medial portal that might be used either for arthroscopic insertion, probing, or instrumental manipulation. The two portals mentioned in the literature are the anterolateral and the posterolateral portals. For evaluating the possibility of establishing a medial portal, six embalmed adult cadaver feet were used to study the anatomical relations to the proposed medial portal. The subtalar joints of another six fresh adult cadaver feet were then arthroscoped, after distraction of the joint, using the anterolateral, posterolateral, and medial portals. Findings indicated that the medial portal gives good visualization of the posterior subtalar joint. Clinical application has not yet been assessed.

The tendo Achillis as it relates to rearfoot position. A new classification for evaluation of calcaneal stance position.

In summary, it has been demonstrated by the statistical analysis of 48 subjects (96 feet) that as the foot moves from the neutral to the resting calcaneal stance position, the tendo Achillis alignment is displaced lateral to the center of gravity. Class I heels demonstrated a direct correlation with tendo Achillis deviation suggesting that their subtalar joint motion is in the transverse plane. Class II and III heels did not directly correlate with Achilles deviation, suggesting probable frontal plane variability. Class IV heels showed no correlation with rearfoot pathology and are considered to be a consequence of distal or proximal pronatory forces. We advocate the recognition of the Achilles tendon as it interacts with transverse and frontal plane subtalar joint motion and believe that it deserves ample attention when evaluating the patient biomechanically as well as surgically.