The effects of medial and lateral displacement calcaneal osteotomies on ankle and subtalar joint pressure distribution

Determining the changes in morphology and loading status following medial displacement calcaneal osteotomy for flatfoot using patient-specific finite element models

Medial displacement calcaneal osteotomy (MDCO) is the standard procedure for flatfoot. We investigated the effect of MDCO on the foot using a finite element analysis. Foot models were created from computed tomography data of 8 patients with flat feet. MDCO was performed on each model with bone translation distance of 4, 8, and 12 mm. The morphological changes, plantar pressures, and stress percentage on the talocrural and subtalar joints were evaluated before and after surgery. Morphological evaluation showed improvement in the medial longitudinal arch. The stress percentage of plantar pressure in the medial area decreased, and the stress percentage of plantar pressure in the mid- and lateral forefoot area increased. At the talocrural joint, the medial and middle stress percentage increased, while the lateral and posterior stress percentage decreased. In the subtalar joint, the stress percentage in the middle subtalar joint increased and that in the posterior subtalar joint decreased. Within the posterior subtalar joint, the anterior and medial stress percentage increased, while the posterior and lateral stress percentage decreased. Preoperative simulation using the finite element analysis may be useful in understanding postoperative morphological changes and loading conditions to perform patient-specific surgery.

Deformity Correction: Do Osteochondral Lesion of the Talus and Tibia Change After Realignment Surgery?

Malalignment of the lower limb, distal tibia, foot, and hindfoot can all contribute to altered biomechanics in the ankle joint, resulting in increased focal pressure. The development of some osteochondral lesions of the ankle joint may share a similar pathophysiology, where eccentric loading to the talus or tibia within the ankle joint can lead to cartilage injury or adaptive changes. While the association between malalignment and the development of osteochondral lesions of the ankle joint may seem intuitive, the impact of realignment procedures on these lesions and patient symptoms remains a relatively underexplored topic in the literature. A comprehensive understanding of the potential role of realignment surgery in managing osteochondral lesions of the talus and tibia is crucial for advancing our knowledge of this challenging pathologic condition.

Testing protocols and measurement techniques when using pressure sensors for sport and health applications: A comparative review

Plantar pressure measurement systems are routinely used in sports and health applications to assess locomotion. The purpose of this review is to describe and critically discuss: (a) applications of the pressure measurement systems in sport and healthcare, (b) testing protocols and considerations for clinical gait analysis, (c) clinical recommendations for interpreting plantar pressure data, (d) calibration procedures and their accuracy, and (e) the future of pressure sensor data analysis. Rigid pressure platforms are typically used to measure plantar pressures for the assessment of foot function during standing and walking, particularly when barefoot, and are the most accurate for measuring plantar pressures. For reliable data, two step protocol prior to contacting the pressure plate is recommended. In-shoe systems are most suitable for measuring plantar pressures in the field during daily living or dynamic sporting movements as they are often wireless and can measure multiple steps. They are the most suitable equipment to assess the effects of footwear and orthotics on plantar pressures. However, they typically have lower spatial resolution and sampling frequency than platform systems. Users of pressure measurement systems need to consider the suitability of the calibration procedures for their chosen application when selecting and using a pressure measurement system. For some applications, a bespoke calibration procedure is required to improve validity and reliability of the pressure measurement system. The testing machines that are commonly used for dynamic calibration of pressure measurement systems frequently have loading rates of less than even those found in walking, so the development of testing protocols that truly measure the loading rates found in many sporting movements are required. There is clear potential for AI techniques to assist in the analysis and interpretation of plantar pressure data to enable the more complete use of pressure system data in clinical diagnoses and monitoring.

Impact of the medial displacement calcaneal osteotomy on foot biomechanics: a systematic literature review

INTRODUCTION

Progressive collapsing foot deformity (PCFD), formally known as "adult-acquired flatfoot deformity" (AAFFD), is a complex foot deformity consisting of multiple components. If surgery is required, joint-preserving procedures, such as a medial displacement calcaneal osteotomy (MDCO), are frequently performed. The aim of this systematic review is to provide a summary of the evidence on the impact of MDCO on foot biomechanics.

MATERIALS AND METHODS

A systematic literature search across two major sources (PubMed and Scopus) without time limitation was performed according to the Preferred Reporting Items for Systematic Review and Meta-Analyses (PRISMA) criteria. Only original research studies reporting on biomechanical changes following a MDCO were included. Exclusion criteria consisted of review articles, case studies, and studies not written in English. 27 studies were included and the methodologic quality graded according to the QUACS scale and the modified Coleman score.

RESULTS

The 27 included studies consisted of 18 cadaveric, 7 studies based on biomechanical models, and 2 clinical studies. The impact of MDCO on the following five major parameters were assessed: plantar fascia (n = 6), medial longitudinal arch (n = 9), hind- and midfoot joint pressures (n = 10), Achilles tendon (n = 5), and gait pattern parameters (n = 3). The quality of the studies was moderate to good with a pooled mean QUACS score of 65% (range 46-92%) for in-vitro and a pooled mean Coleman score of 58 (range 56-65) points for clinical studies.

CONCLUSION

A thorough knowledge of how MDCO impacts foot function is key in properly understanding the postoperative effects of this commonly performed procedure. According to the evidence, MDCO impacts the function of the plantar fascia and Achilles tendon, the integrity of the medial longitudinal arch, hind- and midfoot joint pressures, and consequently specific gait pattern parameters.

The Unloading Effect of Supramalleolar Versus Sliding Calcaneal Osteotomy for Treatment of Osteochondral Lesions of the Medial Talus: A Biomechanical Study

Background

In patients with osteochondral lesion, defects of the medial talus, or failed cartilage surgery, a periarticular osteotomy can unload the medial compartment.

Purpose

To compare the effects of supramalleolar osteotomy (SMOT) versus sliding calcaneal osteotomy (SCO) for pressure redistribution and unloading of the medial ankle joint in normal, varus-aligned, and valgus-aligned distal tibiae.

Study Design

Controlled laboratory study.

Methods

Included were 8 cadaveric lower legs with verified neutral ankle alignment (lateral distal tibial angle [LDTA] = 0°) and hindfoot valgus within normal range (0°-10°). SMOT was performed to modify LDTA between 5° valgus, neutral, and 5° varus. In addition, a 10-mm lateral SCO was performed and tested in each position in random order. Axial loading (700 N) of the tibia was applied with the foot in neutral alignment in a customized testing frame. Pressure distribution in the ankle joint and subtalar joint, center of force, and contact area were recorded using high-resolution Tekscan pressure sensors.

Results

At neutral tibial alignment, SCO unloaded the medial joint by a mean of 10% ± 10% or 66 ± 51 N (P = .04) compared with 6% ± 12% or 55 ± 72 N with SMOT to 5° valgus (P = .12). The achieved deload was not significantly different (ns) between techniques. In ankles with 5° varus alignment at baseline, SMOT to correct LDTA to neutral insufficiently addressed pressure redistribution and increased medial load by 6% ± 9% or 34 ± 33 N (ns). LDTA correction to 5° valgus (10° SMOT) unloaded the medial joint by 0.4% ± 14% or 20 ± 75 N (ns) compared with 9% ± 11% or 36 ± 45 N with SCO (ns). SCO was significantly superior to 5° SMOT (P = .017) but not 10° SMOT. The subtalar joint was affected by both SCO and SMOT, where SCO unloaded but SMOT loaded the medial side.

Conclusion

SCO reliably unloaded the medial compartment of the ankle joint for a neutral tibial axis. Changes in the LDTA by SMOT did not positively affect load distribution, especially in varus alignment. The subtalar joint was affected by SCO and SMOT in opposite ways, which should be considered in the treatment algorithm.

Clinical Relevance

SCO may be considered a reliable option for beneficial load-shifting in ankles with neutral alignment or 5° varus malalignment.

Commercially available pressure sensors for sport and health applications: A comparative review

Pressure measurement systems have numerous applications in healthcare and sport. The purpose of this review is to: (a) describe the brief history of the development of pressure sensors for clinical and sport applications, (b) discuss the design requirements for pressure measurement systems for different applications, (c) critique the suitability, reliability, and validity of commercial pressure measurement systems, and (d) suggest future directions for the development of pressure measurements systems in this area. Commercial pressure measurement systems generally use capacitive or resistive sensors, and typically capacitive sensors have been reported to be more valid and reliable than resistive sensors for prolonged use. It is important to acknowledge, however, that the selection of sensors is contingent upon the specific application requirements. Recent improvements in sensor and wireless technology and computational power have resulted in systems that have higher sensor density and sampling frequency with improved usability - thinner, lighter platforms, some of which are wireless, and reduced the obtrusiveness of in-shoe systems due to wireless data transmission and smaller data-logger and control units. Future developments of pressure sensors should focus on the design of systems that can measure or accurately predict shear stresses in conjunction with pressure, as it is thought the combination of both contributes to the development of pressure ulcers and diabetic plantar ulcers. The focus for the development of in-shoe pressure measurement systems is to minimise any potential interference to the patient or athlete, and to reduce power consumption of the wireless systems to improve the battery life, so these systems can be used to monitor daily activity. A potential solution to reduce the obtrusiveness of in-shoe systems include thin flexible pressure sensors which can be incorporated into socks. Although some experimental systems are available further work is needed to improve their validity and reliability.

The Relationship between Frontal, Axial Leg Alignment, and Ankle Joint Line Orientation-a Radiographic Analysis of Healthy Subjects

OBJECTIVE

Ankle joint line orientation (AJLO) is influenced by the subtalar foot and frontal leg alignment. However, the influence of axial leg alignment on AJLO remains unclear. The study aimed to analyze the influence of frontal, axial leg alignment on AJLO in healthy subjects.

METHODS

Thirty healthy subjects (60 legs) without prior surgery underwent standing biplanar long leg radiograph (LLR) between 2016 and 2020. AJLO was measured in standing long-leg radiographs relative to the ground. Meary's angle and calcaneal pitch were measured. Hip-knee-ankle angle (HKA), femoral antetorsion, and tibial torsion were assessed with SterEOS software (EOS Imaging, Paris, France). LLR was acquired with the feet directing straight anteriorly, which corresponds to a neutral foot progression angle (FPA). The influence of subtalar, frontal, and axial alignment on AJLO was analyzed in a multiple regression model.

RESULTS

An increase in knee valgus increased relative valgus AJLO by 0.5° (95% CI: 0.2° to 0.7°) per 1° (P < 0.001). A decrease in femoral antetorsion increased relative valgus AJLO by 0.2° (95% CI: 0.1° to 0.2°) per 1° (P < 0.001), whereas Meary's angle and calcaneal pitch did not influence AJLO.

CONCLUSION

A link between frontal, axial leg alignment, and AJLO could be demonstrated, indicating that a valgus leg alignment and relative femoral retrotorsion are associated with an increase of valgus AJLO in healthy subjects when placing their feet in a neutral position. Alteration of the frontal, or rotational profile after realignment surgery or by implant positioning might influence the AJLO, when the FPA is kept constant.

Joint Preserving Surgery for Valgus Ankle Osteoarthritis

Valgus ankle OA is a complex problem with multiple etiologies that can either be isolated or superimposed on top of other medical or musculoskeletal disorders. Proper medical history, physical, and preoperative radiological examinations are crucial in deciding on surgery and planning the surgical approach. JPS, especially the varisating medial closing-wedge SMOT with solid plate fixation, has been consistently associated with good outcomes for patients with valgus ankle OA. To further improve JPS for valgus ankle OA, further clinical and biomechanical studies are required to address the long-term clinical and functional outcomes and complications.

Joint Preservation Strategies for Managing Varus Ankle Deformities

Joint preserving strategies have evolved to a successful treatment option in early and midstage medial ankle OA caused by varus deformity. Though talar tilt can often not be fully corrected, it provides substantial postoperative pain relief, functional improvement, and slowing of the degenerative process. Osseous balancing with osteotomies is the main step for restoration of ankle mechanics and normalization of joint load. Overall, the key for success is to understand the underlying causes that have contributed to the varus OA in each case, and to use all treatment modalities necessary to restore appropriate alignment of the hindfoot complex.

Calcaneal Osteotomies in the Treatment of Progressive Collapsing Foot Deformity. What are the Restrictions for the Holy Grail?

The progressive collapsing foot deformity is a complex three-dimensional deformity, including valgus malalignment of the heel. The medial displacement calcaneal osteotomy is an established surgical procedure reliably resulting in an efficient correction of the inframalleolar alignment. However, complications are common, including undercorrection of underlying deformity, progression of hindfoot osteoarthritis and/or deformity, and/or symptomatic hardware.

Tendon lengthening after achilles tendon rupture-passive effects on the ankle joint in a cadaveric pilot study simulating weight bearing

BACKGROUND

In recent years, primary Achilles tendon ruptures have increased due to the aging population's participation in physically demanding activities. These injuries commonly occur during recreational sports and frequently lead to a long-term reduction in activity despite treatment. Non-operative methods of treatment for Achilles tendon ruptures may result in the Achilles healing in a lengthened position compared to the pre-injury state. This study uses a cadaveric model that simulates static weight bearing to explore the effect of a lengthened Achilles tendon on ankle joint load distribution.

METHODS

Five lower limb cadaveric specimens were placed on a custom jig, where a 334 N (75 lb) load was applied at the femoral head, and the foot was supported against a plate to simulate static double-leg stance. A pressure mapping sensor was inserted into the ankle joint. A percutaneous triple hemiresection tendo-Achilles lengthening procedure (Hoke procedure) was performed on each specimen to simulate tendon lengthening after conservative treatment. Contact pressure, peak pressure, and center-of-pressure were measured for native and tendon-lengthened conditions.

RESULTS

Tendon rupture did not significantly alter average contact pressure, peak contact pressures, or center-of-pressure in the ankle joint compared with native tendon.

CONCLUSION

Achilles lengthening does not significantly change contact pressures of the ankle joint in this model . This result suggests that the passive restraint on ankle joint translation imposed by the Achilles tendon is minimal without muscle activation.

Surgical Biomechanics: Principles of Procedure Choice

Surgical treatment of foot and ankle ailments is common, but in the past the choice of procedures was often dictated principally by positional considerations. This article reviews the use of the 2 primary biomechanical approaches, the kinematic and kinetic methods, and presents a novel unified method to guide surgical procedure choice, the kineticokinematic approach. Decision-making methods and resources are discussed and 2 case studies are presented to elucidate how this method may be used when choosing surgical procedures.

The incision strategy for minimizing sural nerve injury in medial displacement calcaneal osteotomy: a cadaveric study

Background

The skin incision for medial displacement calcaneal osteotomy (MDCO) often damages the sural nerve. We aimed to identify the practical reference area in which the surgeon can incise the skin to minimize the injury of the sural nerve during MDCO.

Methods

The foot and ankles of 20 cadavers were dissected. The landmarks were the following four anatomical references: point A, the tip of the lateral malleolus; point B, the inferior margin of the calcaneus on the vertical line through point A; point C, the posteroinferior apex of the calcaneus; and point D, the lateral border of the Achilles tendon on the horizontal line through point A. The distances from the sural nerve to points A and B in the vertical direction (lines D1 and D2, respectively), to points A and C in the diagonal direction (lines D3 and D4, respectively), and to points A and D in the horizontal direction (lines D5 and D6, respectively) were measured.

Results

The median ratios of D1 to D1+D2, D3 to D3+D4, and D5 to D5+D6 were 0.34 (range 0.25 to 0.45), 0.23 (range 0.16 to 0.33), and 0.38 (range 0.26 to 0.50), respectively.

Conclusions

The distance ratios according to easily identifiable references would be a more practical incision strategy for surgeons to minimize sural nerve injury in both open and minimally invasive/percutaneous MDCO.

Management of Posttraumatic Ankle Arthritis: Literature Review

PURPOSE OF REVIEW

Trauma is the principle cause of osteoarthritis in the ankle, which is associated with significant morbidity. This review highlights the current literature for the purpose of bringing the reader up-to-date on the management of posttraumatic ankle arthritis, describing treatment efficacy, indications, contraindications, and complications.

RECENT FINDINGS

Recent studies on osteoarthritis have demonstrated variability among anatomic locations regarding the mechanisms and rates of development for posttraumatic osteoarthritis, which are attributed to newly discovered biological differences intrinsic to each joint. Regarding surgical management of posttraumatic ankle arthritis, osteochondral allograft transplantation of the talus, and supramalleolar osteotomies have demonstrated promising results. Additionally, the outpatient setting was found to be appropriate for managing pain following total ankle arthroplasty, associated with low complication rates and no readmission. Management for posttraumatic ankle arthritis is generally progressive. Initial treatment entails nonpharmacologic options with surgery reserved for posttraumatic ankle arthritis refractory to conservative treatment. Patient demographics and lifestyles should be carefully considered when formulating a management strategy, as outcomes are dependent upon the satisfaction of each set of respective criteria. Ultimately, the management of posttraumatic ankle arthritis should be individualized to satisfy the needs and desires, which are specific to each patient.

Comparison of Lateralizing Calcaneal Osteotomies for Varus Hindfoot Correction

BACKGROUND

There is limited consensus on the optimal operative technique for correcting heel varus in patients with Charcot-Marie-Tooth (CMT) disease. This comparative study evaluated the ability of 4 lateralizing calcaneal osteotomies, with and without Dwyer wedge resection and coronal rotation of the posterior tuberosity, to correct severe heel varus.

METHODS

The computed tomography (CT) scan of a teenage CMT patient with severe hindfoot varus was used to create 3-dimensional (3D)-printed models of the talus, calcaneus, and cuboid. A custom jig facilitated precise replication of the osteotomy cuts. Four different configurations were created: oblique osteotomy with lateralization, oblique osteotomy with lateralization and internal rotation of the posterior tuberosity, Dwyer wedge resection with lateralization, and Dwyer wedge resection with lateralization and internal rotation. CT scans were performed on each model before and after osteotomy. Statistical analysis was used to evaluate differences in several predefined radiographic parameters.

RESULTS

The sequential transformations generated increasing lateral translation of the weight-bearing calcaneus. Dwyer wedge osteotomy significantly improved lateralization (effect = 8.0 mm), valgus hindfoot angle (effect = 6.1 degrees), and coronal calcaneal tilt (effect = -17.6 degrees) compared with the oblique osteotomy. Internal rotation of the posterior tuberosity further improved lateralization (effect = 3.3 mm), valgus hindfoot angle (effect = 2.5 degrees), and coronal calcaneal tilt (effect = -11.7 degrees). Dwyer osteotomy models had on average 5-mm shorter posterior tuberosity lengths than the oblique osteotomies. The addition of rotation did not significantly affect length.

CONCLUSIONS

Significant lateralization of the posterior tuberosity was achieved in all transformations. The Dwyer wedge osteotomy improved hindfoot valgus angle, coronal calcaneal tilt, and lateralization of the weight-bearing surface compared with oblique osteotomy. Posterior tuberosity internal rotation further lateralized the plantar surface and normalized weight bearing. Lateralization, combined with Dwyer osteotomy and coronal plane internal rotation, achieved the greatest correction of varus heel.

CLINICAL RELEVANCE

This study compares multiple lateralizing calcaneal osteotomies and proposes a combined technique of lateralization, Dwyer wedge resection, and coronal plane rotation to address advanced cavovarus hindfoot deformities.

Pressure Distribution in the Ankle and Subtalar Joint With Routine and Oversized Foot Orthoses

BACKGROUND

Foot orthoses are used to treat many disorders that affect the lower limb. These assistive devices have the potential to alter the forces, load distribution, and orientation within various joints in the foot and ankle. This study attempts to quantify the effects of orthoses on the intra-articular force distribution of the ankle and subtalar joint using a cadaveric testing jig to simulate weight bearing.

METHODS

Five lower-limb cadaveric specimens were placed on a custom jig, where a 334-N (75-lb) load was applied at the femoral head, and the foot was supported against a plate to simulate double-leg stance. Pressure-mapping sensors were inserted into the ankle and subtalar joint. Mean pressure, peak pressure, contact area, and center of force were measured in both the ankle and subtalar joints for barefoot and 2 medial foot orthosis conditions. The 2 orthosis conditions were performed using (1) a 1.5-cm-height wedge to simulate normal orthoses and (2) a 3-cm-height wedge to simulate oversized orthoses.

RESULTS

The contact area experienced in the subtalar joint significantly decreased during 3-cm orthotic posting of the medial arch, but neither orthosis had a significant effect on the spatial mean pressure or peak pressure experienced in either joint.

CONCLUSION

The use of an oversized orthosis could lead to a decrease in the contact area and alterations in the distribution of pressure within the subtalar joint.

CLINICAL RELEVANCE

The use of inappropriate orthoses could negatively impact the force distribution in the lower limb.

Use of 3D Prints to Compare the Efficacy of Three Different Calcaneal Osteotomies for the Correction of Heel Varus

BACKGROUND

Cavovarus deformity of the hindfoot is typically caused by neurologic disorders. Multiple osteotomies have been described for the correction of varus deformity but without clinical comparison. In this study, we used 18 identical 3-dimensional (3D) prints of a patient with heel varus to compare the operative correction obtained with Dwyer, oblique, and Z osteotomies.

METHODS

A computed tomography (CT) scan of a patient with heel varus was used to create 18 identical 3D prints of the talus, calcaneus, and cuboid. Coordinate frames were added to the talus and calcaneus to evaluate rotation. The prints were then divided into 3 groups of 6 models each. A custom jig precisely and accurately replicated each osteotomy. Following the simulated operations, cut models were CT scanned and compared with 6 uncut models. Measurements were calculated using multiplanar reconstruction image processing. An analysis of variance (ANOVA) was performed on the initial data to determine significant differences among the measured variables. A Tukey Studentized range test was run to compare variables that showed statistically significant differences using the ANOVA.

RESULTS

The coronal angle of the Dwyer and oblique osteotomies was significantly less than that of the Z osteotomy ( P < .05). The axial angle, lateral displacement, and calcaneal shortening of the uncut model and Z osteotomy were significantly less than the Dwyer and oblique osteotomies.

CONCLUSIONS

Dwyer, oblique, and Z osteotomies did not create either lateral translation or coronal rotation without the addition of a lateralizing slide or rotation of the posterior tuberosity.

CLINICAL RELEVANCE

Dwyer and oblique osteotomies would be best suited for mild deformity, yet the amount of calcaneal shortening must be acknowledged. A Z osteotomy is a complex procedure that has the capability of correcting moderate-severe coronal plane rotation but fails to provide lateralization of the pull of the Achilles insertion.

Changes in ankle joint motion after Supramalleolar osteotomy: a cadaveric model

Background

Malalignment of the ankle joint has been found after trauma, by neurological disorders, genetic predisposition and other unidentified factors, and results in asymmetrical joint loading. For a medial open wedge supramalleolar osteotomy(SMO), there are some debates as to whether concurrent fibular osteotomy should be performed. We assessed the changes in motion of ankle joint and plantar pressure after supramalleolar osteotomy without fibular osteotomy.

Methods

Ten lower leg specimens below the knee were prepared from fresh-frozen human cadavers. They were harvested from five males (10 ankles)whose average age was 70 years. We assessed the motion of ankle joint as well as plantar pressure for SS(supra-syndesmotic) SMO and IS(intra-syndesmotic) SMO. After the osteotomy, each specimen was subjected to axial compression from 20 N preload to 350 N representing half-body weight. For the measurement of the motion of ankle joint, the changes in gap and point, angles in ankle joint were measured. The plantar pressure were also recorded using TekScan sensors.

Results

The changes in the various gap, point, and angles movements on SS-SMO and IS-SMO showed no statistically significant differences between the two groups. Regarding the shift of plantar center of force (COF) were noted in the anterolateral direction, but not statistically significant.

Conclusions

SS-SMO and IS-SMO with intact fibula showed similar biomechanical effect on the ankle joint. We propose that IS-SMO should be considered carefully for the treatment of osteoarthrosis when fibular osteotomy is not performed because lateral cortex fracture was less likely using the intrasyndesmosis plane because of soft tissue support.

Minimally invasive calcaneal osteotomy: A cadaveric and clinical evaluation

BACKGROUND

A cadaveric and clinical study was performed to assess whether a minimally invasive technique is a potentially safer alternative compared to a calcaneal osteotomy through an open lateral approach.

METHODS

Cadaveric: A minimally invasive calcaneal osteotomy (MICO) was performed on nine cadaveric specimens. These were examined to identify any nerve injury and to quantify the displacement achieved with the osteotomy. Clinical: A retrospective review of a sequential case series of medializing MICO's performed by the senior author between October 2011 and November 2014 was undertaken.

RESULTS

Cadaveric: Neurological structures remained uninjured in all specimens. The distance of the sural nerve and the main trunk of the tibial nerve to the superior limb of the oblique osteotomy was 6.2±4.8mm (range 0-14mm) and 7.3±3.6mm (range 4-12mm), respectively. The mean coronal shift achieved was 16.7±3.4mm (range 12-21mm). Clinical: The senior author carried out 35 medializing MICO procedures. Radiological and clinical union occurred in all 35 cases (100%). There were no neurovascular or wound complications.

CONCLUSION

Minimally invasive calcaneal osteotomy offers a safe alternative to an open procedure with promising clinical results.

Effects of Medial Displacement Calcaneal Osteotomy and Calcaneal Z Osteotomy on Subtalar Joint Pressures: A Cadaveric Flatfoot Model

Medial displacement calcaneal osteotomies have been shown to be successful in the surgical management of adult acquired flatfoot, in particular, stage 2 deformity. Classically, the medial displacement calcaneal osteotomy technique has been performed. However, a calcaneal Z osteotomy has been more recently described and applied in the surgical management of flatfoot deformity. Although the potential advantages of the calcaneal Z technique have been reported, data on its effect on the subtalar joint are lacking. A validated flatfoot model was induced in 8 cadaveric feet that had been randomly assigned to either medial displacement calcaneal osteotomy (n = 4) or calcaneal Z osteotomy (n = 4). The feet were loaded through the tibia with a constant ground reaction force of 400 N, with a simultaneous increase in the Achilles tendon force to 300 or 500 N. The subtalar joint pressures were recorded before and after osteotomy. We did not detect any statistically significant differences between the 2 techniques in terms of their effects on subtalar joint pressure.

Supramalleolar Osteotomies for the Treatment of Ankle Arthritis

Supramalleolar osteotomy is a joint-preserving surgical treatment for patients with asymmetric valgus or varus ankle arthritis. The primary goal of the procedure is to realign the spatial relationship between the talus and tibia and thereby normalize joint loading within the ankle. Procedures to balance the soft tissues, as well as hindfoot osteotomy and arthrodesis, may also be necessary. Clinical studies of supramalleolar osteotomy demonstrate that correction of the altered biomechanics associated with asymmetric arthritis improves functional outcomes.

[Dwyer osteotomy : Lateral sliding osteotomy of calcaneus]

OBJECTIVE

To correct the underlying inframalleolar varus deformity and to restore physiologic biomechanics of the hindfoot.

INDICATIONS

Neurologic, posttraumatic, congenital, and idiopathic cavovarus deformity. In patients with end-stage ankle osteoarthritis with varus heel malposition as additional single-stage procedure complementing total ankle replacement. Severe peroneal tendinopathy with concomitant cavovarus deformity.

CONTRAINDICATIONS

General surgical or anesthesiological risks, infections, critical soft tissue conditions, nonmanageable hindfoot instability, neurovascular impairment of the lower extremity, neuroarthropathy (e. g., Charcot arthropathy), end-stage osteoarthritis of the subtalar joint, severely reduced bone quality, high age, insulin-dependent diabetes mellitus, smoking.

SURGICAL TECHNIQUE

The lateral calcaneus cortex is exposed using a lateral incision. The osteotomy is performed through an oscillating saw. The posterior osteotomy fragment is manually mobilized and shifted laterally. If needed, a laterally based wedge can be removed and/or the osteotomy fragment can be translated cranially. The osteotomy is stabilized with two cannulated screws, followed by wound closure.

POSTOPERATIVE MANAGEMENT

A soft wound dressing is used. Thromboprophylaxis is recommended. Patient mobilization starts on postoperative day 1 with 15 kg partial weight bearing using a stabilizing walking boot or cast for 6 weeks. Following clinical and radiographic follow-up at 6 weeks, full weight bearing is initiated step by step.

RESULTS

Between January 2009 and June 2013, a Dwyer osteotomy was performed in 31 patients with a mean age of 45.7 ± 16.3 years (range 21.5-77.4 years). All patients had a substantial inframalleolar cavovarus deformity with preoperative moment arm of the calcaneus of -17.9 ± 3.3 mm (range -22.5 to -10.5 mm), which has been improved significantly to 1.6 ± 5.9 mm (range -16.9 to 9.9 mm). Significant pain relief from 6.3 ± 1.9 (range 4-10) to 1.1 ± 1.1 (range 0-4) using the visual analogue scale was observed. The American Orthopaedic Foot and Ankle Society score significantly improved from 33.1 ± 14.2 (range 10-60) to 78.0 ± 10.5 (range 55-95).

Hindfoot deformity and calcaneal tuberosity osteotomies

Calcaneal tuberosity osteotomies are commonly used to treat coronal plane deformities of the hindfoot. Assessing hindfoot alignment can be difficult and there is little evidence to guide the physician when considering the surgical treatment of these deformities. The indications for a calcaneal osteotomy are unclear in the literature because most of the published studies supporting their use are confounded by concurrent procedures such as in adult-acquired flatfoot correction or cavovarus reconstruction. For the same reason, the biomechanical consequences, long-term effects, and performance in vivo are largely unknown.

LEVEL OF EVIDENCE

Expert opinion, Level V.

Subtalar joint configuration on weightbearing CT scan

BACKGROUND

Standard values that describe the morphology of the subtalar (ST) joint have previously been obtained from cadaveric studies or by using conventional unloaded radiographs. It is known that these parameters differ significantly from those measured in vivo and in loaded images, limiting the diagnostic value of the previously published morphological parameters in the literature. However, the morphology of the ST joint clearly affects its function. The objective of this study was to determine the morphology of the posterior facet of the ST joint using loaded computed tomography (CT) images and to describe the different configurations found in asymptomatic patients.

METHODS

A weightbearing CT scan was performed on 59 patients without any history of hindfoot and ankle pathology. The shape of the posterior facet and the subtalar vertical angle (SVA) were measured in 3 different coronal planes of the ST joint.

RESULTS

The posterior facet was concave in 88% and flat in 12%. The posterior facet was oriented in valgus in 90% and varus in 10% when measured in the middle coronal plane. However, the SVA changed depending on which coronal plane it was measured in.

CONCLUSION

We believe it is important to get a better insight into the morphological parameters of the ST joint.

CLINICAL RELEVANCE

Knowledge of subtalar joint morphology could help clarify why certain failures have occurred in reconstructive hindfoot surgery and thus might help plan the surgical procedure to reduce these failures in the future.

Site-specific loading at the fifth metatarsal base in rehabilitative devices: implications for Jones fracture treatment

BACKGROUND

Fractures of the fifth metatarsal base are a relatively common injury. Whether treated surgically or nonsurgically, injury rehabilitation typically involves immobilization in a rigid sandal or short controlled ankle movement (CAM) walker boot.

OBJECTIVE

To determine the peak pressure, contact pressure, and impulse at the base of the fifth metatarsal in 3 common footwear devices during common gait activities.

DESIGN

This was a retrospective comparative study.

SETTING

Research was conducted in a sports performance laboratory at a university.

PARTICIPANTS

Twenty subjects without a recent history of foot injuries volunteered to participate.

METHODS

Each subject performed 3 common gait activities (walking, heel walking, and pivoting) in 3 footwear devices (short CAM walker boot, postoperative sandal, running shoe). Pressure data were sampled (100 Hz) using individually sized plantar pressure insoles and software (Tekscan). Walking trials were collected at 1.0 m/s ± 5% (FusionSport Timing Gates).

OUTCOME MEASUREMENTS

Peak pressure, contact pressure, and impulse at the fifth metatarsal base region were determined for all trials for all subjects. Mixed-effect regression models were used to compare pairwise differences in outcome variables between footwear devices.

RESULTS

The CAM walker boot resulted in significantly lower peak pressure at the fifth metatarsal during walking and heel-walking relative to the postoperative sandal (P < .01) and during heel-walking (P < .01) relative to the standard athletic shoe. The CAM walker boot significantly reduced contact pressures at the fifth metatarsal during walking and heel-walking relative to the postoperative sandal (P < .01), and during heel-walking relative to the standard athletic shoe (P < .001).

CONCLUSIONS

Our results suggest that the short CAM walker boot more effectively offloads the fifth metatarsal during common gait activities than a postoperative sandal or a standard athletic shoe. A short CAM walker boot may be a beneficial rehabilitative tool for patients undergoing rehabilitation after treatment of Jones fractures and other base of fifth metatarsal fractures.

Effect of supramalleolar osteotomy and total ankle replacement on talar position in the varus osteoarthritic ankle: a comparative study

BACKGROUND

In varus osteoarthritic ankles, joint congruency is usually lost leading to progressive wear of the medial tibiotalar joint. Recent studies have shown that balancing the hindfoot with the aid of supramalleolar osteotomy (SMOT) is an effective method to decrease symptoms and to delay progression of osteoarthritis of the ankle joint. Resurfacing the articular surfaces with total ankle replacement (TAR), in contrast, may compensate for the lost joint congruency and lost stability of the talus at the peritalar joint. However, no literature exists with regard to the overall correction of talar position in all 3 planes when using these 2 treatment modalities. The purpose of this study was to determine the effect of SMOT and TAR on talar position in all 3 planes, and to compare the efficiency of both procedures in restoring overall hindfoot geometry.

METHODS

Out of 104 ankles with a varus-tilted ankle, 52 patients were treated with SMOT and 52 with TAR. Weight-bearing radiographs were analyzed to measure the talar position in all 3 planes, including the talar tilt angle (TT), the sagittal talocalcaneal inclination angle (TCI), and the talometatarsal 1 angle (TMT1) pre- and postoperatively.

RESULTS

Although after TAR the talar position was corrected in all the 3 planes, SMOT on the other hand did not fully correct the TT, and furthermore TMT1 remained unchanged.

CONCLUSIONS

Resurfacing of the worn-out articular surface and tensioning of ligaments, as is the case in TAR, radiographically restores the hindfoot geometry in the neutral position better than SMOT does.

LEVEL OF EVIDENCE

Level III, retrospective comparative study.

Geometry of the lateral sliding, closing wedge calcaneal osteotomy: review of the two methods and technical tip to minimize shortening

BACKGROUND

A lateral closing wedge osteotomy is used for correction of varus hindfoot deformities. Since its original description, different techniques and geometries of the calcaneal bone wedge resection have been described. Even though the techniques seem similar, very different final bone architectures result from each technique, the effects of which are not known. This paper explores several of these techniques and the implications in deformity correction as well as the secondary effects of calcaneal shortening.

METHODS

Mathematical and geometric analysis is performed in 2-dimensions for several hypothetical calcaneal osteotomies as described by the original authors. The resulting changes are calculated and compared.

RESULTS

The shape of the bone resection for the lateral closing wedge osteotomy does not result in significantly different final calcaneal architectures. Both techniques studied result in the same amount of calcaneal shortening and deformity correction. However, when lateral calcaneal wedge resection is combined with lateral translation of the tuberosity for additional deformity correction, more calcaneal shortening is seen with posteriorly directed osteotomies than those that are transverse.

CONCLUSION

The lateral closing wedge osteotomy of the calcaneus results in correction of varus hindfoot deformity at the expense of some calcaneal shortening. Lateral translation of the tuberosity may result in additional calcaneal. The clinical effects of calcaneal shortening or medial soft tissue or nerve tethering from these different techniques are unknown and deserve further investigation.

LEVEL OF EVIDENCE

Level V, expert opinion.

What is the role and limit of calcaneal osteotomy in the cavovarus foot?

Calcaneal osteotomy is a commonly used tool in cavovarus foot reconstructions. Understanding the indications and limitations of such an osteotomy is critical to success in reconstruction. We present a comprehensive review of surgical calcaneal osteotomy techniques and the currently available state of literature for their indications and limitations.

Ankle joint pressure changes in a pes cavovarus model: supramalleolar valgus osteotomy versus lateralizing calcaneal osteotomy

BACKGROUND

A fixed cavovarus foot deformity can be associated with anteromedial ankle arthrosis due to elevated medial joint contact stresses. Supramalleolar valgus osteotomies (SMOT) and lateralizing calcaneal osteotomies (LCOT) are commonly used to treat symptoms by redistributing joint contact forces. In a cavovarus model, the effects of SMOT and LCOT on the lateralization of the center of force (COF) and reduction of the peak pressure in the ankle joint were compared.

METHODS

A previously published cavovarus model with fixed hindfoot varus was simulated in 10 cadaver specimens. Closing wedge supramalleolar valgus osteotomies 3 cm above the ankle joint level (6 and 11 degrees) and lateral sliding calcaneal osteotomies (5 and 10 mm displacement) were analyzed at 300 N axial static load (half body weight). The COF migration and peak pressure decrease in the ankle were recorded using high-resolution TekScan pressure sensors.

RESULTS

A significant lateral COF shift was observed for each osteotomy: 2.1 mm for the 6 degrees (P = .014) and 2.3 mm for the 11 degrees SMOT (P = .010). The 5 mm LCOT led to a lateral shift of 2.0 mm (P = .042) and the 10 mm LCOT to a shift of 3.0 mm (P = .006). Comparing the different osteotomies among themselves no significant differences were recorded. No significant anteroposterior COF shift was seen. A significant peak pressure reduction was recorded for each osteotomy: The SMOT led to a reduction of 29% (P = .033) for the 6 degrees and 47% (P = .003) for the 11 degrees osteotomy, and the LCOT to a reduction of 41% (P = .003) for the 5 mm and 49% (P = .002) for the 10 mm osteotomy. Similar to the COF lateralization no significant differences between the osteotomies were seen.

CONCLUSION

LCOT and SMOT significantly reduced anteromedial ankle joint contact stresses in this cavovarus model. The unloading effects of both osteotomies were equivalent. More correction did not lead to significantly more lateralization of the COF or more reduction of peak pressure but a trend was seen.

CLINICAL RELEVANCE

In patients with fixed cavovarus feet, both SMOT and LCOT provided equally good redistribution of elevated ankle joint contact forces. Increasing the amount of displacement did not seem to equally improve the joint pressures. The site of osteotomy could therefore be chosen on the basis of surgeon's preference, simplicity, or local factors in case of more complex reconstructions.

Joint-preserving surgery of valgus ankle osteoarthritis

Patients with posttraumatic ankle osteoarthritis (OA) typically present with asymmetric involvement of the tibiotalar joint, resulting in valgus or varus deformity of the ankle and hindfoot. Without appropriate treatment, patients with asymmetric ankle OA typically develop full end-stage ankle OA. Ankles with valgus deformities suffer from a lateral joint overload with subsequent lateral tibiotalar joint degeneration, which causes further lateral load shift. In these cases patients may benefit from joint-preserving realignment surgery to unload the degenerated lateral area and normalize joint biomechanics. This article describes the authors' algorithm for the treatment of patients with asymmetric valgus ankle OA.

The role of the fibula in varus and valgus deformity of the tibia

It has been suggested that a supramalleolar osteotomy can return the load distribution in the ankle joint to normal. However, due to the lack of biomechanical data, this supposition remains empirical. The purpose of this biomechanical study was to determine the effect of simulated supramalleolar varus and valgus alignment on the tibiotalar joint pressure, in order to investigate its relationship to the development of osteoarthritis. We also wished to establish the rationale behind corrective osteotomy of the distal tibia.

We studied 17 cadaveric lower legs and quantified the changes in pressure and force transfer across the tibiotalar joint for various degrees of varus and valgus deformity in the supramalleolar area. We assumed that a supramalleolar osteotomy which created a varus deformity of the ankle would result in medial overload of the tibiotalar joint. Similarly, we thought that creating a supramalleolar valgus deformity would cause a shift in contact towards the lateral side of the tibiotalar joint. The opposite was observed. The restricting role of the fibula was revealed by carrying out an osteotomy directly above the syndesmosis. In end-stage ankle osteoarthritis with either a valgus or varus deformity, the role of the fibula should be appreciated and its effect addressed where appropriate.

Incidence of plantar lateral foot pain before and after the use of trial metal wedges in lateral column lengthening

BACKGROUND

One of the major concerns with lateral column lengthening (LCL) in symptomatic flatfoot deformity treatment is the risk of postoperative plantar lateral foot discomfort. We evaluated whether this risk can be minimized by using trial metal wedges. Using our study's evaluation tools, the incidence of postoperative plantar lateral foot discomfort before and after using trial metal wedges was determined.

MATERIALS AND METHODS

The incidence of planter lateral foot pain after LCL was retrospectively assessed in 122 consecutive patients (132 feet) after they had undergone flatfoot reconstruction with LCL between 2001 and 2007. To determine if the incidence could be reduced, levels of pain or revision were compared before and after the use of trial metal wedges. The ratio of wedge size to preoperative radiographic calcaneal length was also determined.

RESULTS

The overall incidence of plantar lateral discomfort was 11.2%. The incidence of pain or revision was lower after the introduction of trial metal wedges (6.3% compared to 14.7%), but did not reach significance (p = 0.084). There was no significant difference found in the ratio of the size of bone graft wedge to calcaneal length between the two groups (p = 0.805).

CONCLUSION

The incidence of plantar lateral foot discomfort overall was 11.2% after LCL. We believe this risk may be reduced using trial metal wedges, properly judging eversion stiffness and carefully assessing the position of the foot intraoperatively.

Effect of supramalleolar varus and valgus deformities on the tibiotalar joint: a cadaveric study

BACKGROUND

Distal tibia coronal plane malalignment predisposes the ankle joint to asymmetric load. The purpose of this cadaveric study was to quantify changes in pressure and force transfer in an ankle with a supramalleolar deformity.

MATERIALS AND METHODS

Seventeen cadaveric lower legs were loaded with 700 N after creating supramalleolar varus and valgus deformities. The fibula was left intact in 11 specimens and osteotomized in six. Tekscan© sensors were used to measure the tibiotalar pressure characteristics.

RESULTS

In isolated supramalleolar deformity, the center of force and peak pressure moved in an anteromedial direction for valgus and posterolateral direction for varus deformities. The change was in an anteromedial direction for varus and in a posterolateral direction for valgus deformities in specimens with an osteotomized fibula.

CONCLUSION

Two essentially different groups of varus and valgus deformities of the ankle joint need to be distinguished. The first group is an isolated frontal plane deformity and the second group is a frontal plane deformity with associated incongruency of the ankle mortise.

CLINICAL RELEVANCE

Our findings underline the complexity of asymmetric osteoarthritis of the ankle joint. In addition, results from this study provide useful information for future basic research on coronal plane deformity of the hindfoot and for determining appropriate surgical approaches.

Ankle joint pressure changes in a pes cavovarus model after lateralizing calcaneal osteotomies

BACKGROUND

Tendon transfers and calcaneal osteotomies are commonly used to treat symptoms related to medial ankle arthrosis in fixed pes cavovarus. However, the relative effect of these osteotomies in terms of lateralizing the ground contact point of the hindfoot and redistributing ankle joint contact stresses are unknown.

MATERIALS AND METHODS

Pes cavovarus with fixed hindfoot varus was simulated in eight cadaver specimens. The effect of three types of calcaneal osteotomies on the migration of the center of force and tibiotalar peak pressure at 300 N axial static load (half-body weight) were recorded using pressure sensors.

RESULTS

A significant lateral shift of the center of force was observed: 4.9 mm for the laterally closing Z-shaped osteotomy with additional lateralization of the tuberosity, 3.4 mm for the lateral sliding osteotomy of the calcaneal tuberosity, and 2.7 mm for the laterally closing Z-shaped osteotomy (all p < 0.001). A significant peak pressure reduction was recorded: -0.53 MPa for the Z-shaped osteotomy with lateralization, -0.58 MPa for the lateral sliding osteotomy of the calcaneal tuberosity, and -0.41 MPa for the Z-shaped osteotomy (all p < 0.01).

CONCLUSION

This cadaver study supports the hypothesis that lateralizing calcaneal osteotomies substantially help to normalize ankle contact stresses in pes cavovarus.

Hindfoot motion following reconstruction for posterior tibial tendon dysfunction

INTRODUCTION

Due to advances in technology, segmental gait analysis of the foot is now possible and can elucidate hindfoot deformity in persons with posterior tibial tendon dysfunction (PTTD). This study evaluated the motion of the hindfoot and ankle power following surgical reconstruction for PTTD utilizing a segmental foot model during gait.

MATERIALS AND METHODS

Twenty patients who underwent posterior tibial tendon reconstruction for Stage 2 PTTD using transfer of the flexor digitorum longus tendon to the navicular tuberosity, reconstruction of the calcaneo-navicular ligament complex, and a medial displacement calcaneal osteotomy were evaluated at a minimum followup of 1 year. Three-dimensional gait analysis was performed utilizing a 4-segment foot model. Temporal-spatial parameters included walking velocity, cadence, step length, and single support time. Sagittal, coronal, and transverse hindfoot motion with respect to the tibia/fibula and ankle power was calculated throughout the gait cycle.

RESULTS

Walking velocity, cadence, and step length were not significantly different between the study subjects and the normal control group. Study patients did show a significantly smaller single support time on both the affected and unaffected limbs compared to controls. There was no statistical difference in plantarflexion-dorsiflexion, varus-valgus, or ankle push-off power between the affected and unaffected sides of the study subjects, or between the affected side and the controls.

CONCLUSION

In this preliminary postoperative study, surgical reconstruction for PTTD effects quantifiable objective improvement in walking velocity, hindfoot motion and power.

Results of resection for middle facet tarsal coalitions in adults

The optimum surgical procedure for talocalcaneal coalitions has not been definitively determined. The authors performed this study to evaluate the results achieved with talocalcaneal tarsal coalition resection with regard to preoperative radiographic findings in relation to postoperative outcomes. They reviewed the medical records of 7 patients and conducted telephone interviews using a modified American Orthopaedic Foot and Ankle Society Ankle-Hindfoot Scale. The average age at surgery was 31 years (range, 15-56 years), and the follow-up period averaged 17.4 months (range, 7-36 months). In 6 cases, the resection was successful, with the mean preoperative Ankle-Hindfoot score of 36.5 improving to 50.5 (P = .51). One patient failed the resection and underwent a subtalar arthrodesis 1 year after the resection procedure. Radiographic evaluation showed that higher cartilaginous content of the tarsal coalition was associated with a better outcome in Ankle-Hindfoot scores (r = .894, P = .016); the relationship of patient age and changes in scores was r = .692 but was not statistically significant because of small sample size. Resection of tarsal coalition led to higher Ankle-Hindfoot scores for 6 of 7 patients at least 1 year postoperatively, and that higher cartilagenous content of the coalition was statistically significantly correlated with better postoperative outcomes.

Valgus ankle deformity and arthritis

This article describes several conditions that may result in valgus ankle arthritis. The emphasis is on correction of pathology or deformity to prevent valgus arthritis from developing. The surgical techniques available for the treatment of this form of ankle arthritis, once it develops, are described also.

A comparison of lateral column lengthening and medial translational osteotomy of the calcaneus for the reconstruction of adult acquired flatfoot

BACKGROUND

This study compared the effects of lateral column lengthening and medial translational calcaneal osteotomy on pedal realignment and degeneration of adjacent hindfoot joints noted on radiographs.

METHODS

Forty patients who had either a lateral column lengthening (25 feet) or calcaneal osteotomy (17 feet) to reconstruct a flatfoot were retrospectively reviewed as two groups. Six parameters of foot alignment were measured from weightbearing preoperative, early postoperative, and latest followup radiographs. The magnitude of realignment achieved initially and preserved at latest followup was determined for each group. The talonavicular and subtalar joints were graded for radiographic evidence of arthritis before the reconstruction and at latest followup. Demographic information, complication rate, and reoperation associated with each group also were determined by chart review.

RESULTS

The group that received a lateral column lengthening demonstrated a greater initial realignment than the group treated with a calcaneal osteotomy. The lengthening group also demonstrated greater realignment than the osteotomized group when they were compared at their respective latest followup. The lengthening group had a higher number of adjacent joints with progression of arthritis. The rate of nonunion was higher with a lateral column lengthening; however, the rate of reoperation after an osteotomy was more than twice that observed after a lateral column lengthening.

CONCLUSIONS

The lateral column lengthening group achieved greater realignment initially and maintained correction better over time than the calcaneal osteotomy group while having a lower reoperation rate despite a higher incidence of nonunion and radiographic progression of adjacent joint arthritis.

Calcaneal osteotomies for the treatment of adult-acquired flatfoot

Calcaneal osteotomies are useful procedures for the treatment of stage 2 adult-acquired flatfoot. Often combined with adjunctive soft-tissue procedures, the posterior calcaneal displacement osteotomy and Evans procedure provide effective realignment of pes planovalgus deformity. Preoperative evaluation, indications, contraindications, surgical considerations and techniques are discussed.

Tendon transfers and realignment osteotomies for treatment of stage II posterior tibial tendon dysfunction

Posterior tibial tendon dysfunction (PTTD) has been approached with a multitude of surgical techniques. This article outlines the current understanding of the flexor digitorum longus transfer and flexor hallucis longus transfer in the context of various osteotomy techniques for the correction of stage II PTTD. Pertinent clinical literature and scientific evidence will also be compared and analyzed.

Stage IV posterior tibial tendon rupture

Adult acquired flatfoot deformity progresses through well defined stages as set out by Johnson and Strom. Myerson modified this classification system with the addition of a fourth, more advanced stage of the disease. This stage describes the involvement of the tibiotalar joint in addition to the hindfoot malalignment seen in stages II and III. This most advanced stage is comprised of a hindfoot valgus deformity, resulting from degeneration of the posterior tibial tendon, with associated valgus tilting of the talus within the mortise. The deformity at the tibiotalar joint may or may not be rigid. Although rigid deformities are still best treated with fusions of the ankle and hindfoot, supple tibiotalar deformity may be treated with joint sparing procedures involving reconstructive procedures of the foot and deltoid ligaments.

Effect of tibiotalar joint arthrodesis on adjacent tarsal joint pressure in a cadaver model

BACKGROUND

Tibiotalar arthrodesis is the most common treatment of end-stage symptomatic ankle arthritis, but concerns exist about late findings of adjacent tarsal joint osteoarthritis. The purpose of this study was to evaluate the changes of pressure in the talonavicular, subtalar, and calcaneocuboid joints before and after rigid tibiotalar joint immobilization and at different levels of tibiopedal dorsiflexion.

METHODS

Twelve cadaver foot specimens were cyclically loaded on a servohydraulic test frame to 700 N. Joint contact pressure, peak pressure, and contact area in the three tarsal joints were measured before and after tibiotalar joint immobilization with three 6.5-mm screws to simulate ankle arthrodesis. Measurements were obtained at tibiopedal dorsiflexion angles of 0, 10, 20, and 30 degrees in normal ankle joints and at dorsiflexion angles of 0, 10, and 20 degrees in fixed tibiotalar joints. Paired Student's t-tests and one-way ANOVA with repeated measures were used to analyze the data.

RESULTS

Joint contact pressures did not show any statistically significant difference for the talonavicular and calcaneocuboid joints in the intact ankle. Contact pressures in the talonavicular and calcaneocuboid joints showed significant differences between 0 and 10 degrees and between 0 and 20 degrees of dorsiflexion (p<0.05) in the fused ankle specimens. Comparison of the contact pressure of the talonavicular and the calcaneocuboid joints between the intact and the fused ankle specimens showed a significant difference at 10 and 20 degrees of dorsiflexion (p<0.05). Subtalar joint contact pressure in the intact ankle showed a significant difference between 0 and 30 degrees of dorsiflexion (p<0.05).

CONCLUSIONS

These changes in joint pressures and contact area are consistent with findings of transverse tarsal joint arthritis seen in clinical studies. The current findings suggest that a substantial pressure increase in the talonavicular and calcaneocuboid joints at tibiopedal dorsiflexion levels simulating a late stance phase of the gait cycle may be responsible for the secondary tarsal joint degeneration occurring in late ankle arthrodesis.

Measuring contact area, force, and pressure for bioengineering applications: Using Fuji Film and TekScan systems

The goal of this study was to compare the TekScan I-Scan Pressure Measurement System with two methods of analysis involving the Fuji Film Prescale Pressure Measuring System in estimating area, force and pressure. Fuji Film and TekScan sensors were alternately placed between a cylindrical peg and a finely ground steel base plate, and compressed with known forces. All Fuji stains were digitally scanned and analyzed. The Erase method of Fuji Film analysis consisted of manually removing portions of the image judged by the user to be outside the perimeter of the stain. The second method of Fuji Film analysis, termed the Threshold method, used the threshold tool to analyze only those pixels that were stained from loading. The TekScan system utilized special matrix-based sensors interfaced with a Windows compatible desktop computer that was equipped with specialized data acquisition hardware and analysis software. The data from this study did not support the hypothesis that all three methods would have accuracies within +/-5% of a known value, when estimating area, force and pressure. Specifically, the TekScan system was found to be more accurate than either of the Fuji Film methods when estimating area and pressure.

Effects of a UCBL orthosis and a calcaneal osteotomy on tibiotalar contact characteristics in a cadaver flatfoot model

BACKGROUND

A flatfoot deformity alters the contact characteristics of the ankle joint, shifting the location of articulation posterolaterally, increasing pressure, and decreasing the contact area within the ankle. These changes may explain the pattern of articular degeneration and subsequent angulation observed in a long-standing adult acquired flatfoot. Corrective orthoses and surgical reconstruction have been used to realign pes planovalgus feet, but the effects of these treatments on tibiotalar contact characteristics are unknown. We hypothesized that realignment of a flatfoot with either corrective orthosis or surgical reconstruction would restore the contact characteristics of the ankle to the intact state.

METHODS

The mean value of the contact area, contact pressure, peak contact pressure, and the relative locations of the global contact area and peak pressure within the ankle joint were determined from imprints created on pressure sensitive film for a series of cadaver lower limbs subjected to a weightbearing load in simulated midstance phase of gait. Each limb was loaded sequentially under four conditions: intact, flatfoot, flatfoot realigned with UCBL orthosis, and flatfoot realigned with a medial translational osteotomy of the calcaneus.

RESULTS

The use of the UCBL orthosis and calcaneal osteotomy altered the contact characteristics of the ankle when compared with the flatfoot condition. Both interventions significantly decreased the mean global contact pressure from the flatfoot value, with the orthosis, demonstrating a significantly greater correction than the osteotomy. The orthosis also significantly reduced the peak contact pressure from the flatfoot value. Both interventions significantly corrected the lateral shift of the center of the peak contact pressure from the flatfoot value. The shift in the center of the global contact area approached significance when the orthosis was compared with the flatfoot.

CONCLUSIONS

The changes observed in the magnitude and location of the mean and peak pressures indicate that the UCBL orthosis and calcaneal osteotomy altered hindfoot alignment to significantly influence tibiotalar contact characteristics. The results further suggest that the UCBL orthosis corrected ankle malalignment better than the calcaneal osteotomy in an adult acquired flatfoot. This study provides biomechanical data to support the clinical impression that realignment of the hindfoot corrects the pathologic tibiotalar contact characteristics associated with an adult acquired flatfoot. The results support the conclusion that the clinical management of a pes planovalgus foot with a UCBL orthosis or a medial translational osteotomy of the calcaneus may avert the onset of pantalar disease seen with late-stage posterior tibial tendon dysfunction.

Preliminary gait analysis results after posterior tibial tendon reconstruction: a prospective study

The purpose of this study was to investigate the effect on gait in patients who underwent reconstruction for stage II posterior tibial tendon (PTT) dysfunction. Twelve patients with stage II PTT dysfunction underwent surgical reconstruction consisting of debridement of the posterior tibial tendon, flexor digitorum longus tendon transfer to the navicular tuberosity, medial displacement calcaneal osteotomy, and spring ligament reconstruction. Midfoot arthrodesis was performed in six patients and gastrocnemius recession in three. Gait analysis was performed 2 weeks prior to surgery and 1 year postoperatively. Preoperative and postoperative data were compared to determine differences in temporal-spatial parameters, lower limb kinematics, and ankle push-off power. Step length for the operated side increased from 52.6 +/- 9.6 cm before the surgery to 57.5 +/- 7.1 cm after the surgery (p =.048). Cadence improved from 100.2 +/- 10.7 steps/min to 109.1 +/- 8.5 steps/min (p =.05), thus increasing velocity from 87.6 +/- 22.6 cm/s to 103.4 +/- 15.9 cm/s (p =.042). Single support percentage was unchanged. Maximum sagittal ankle joint power at push-off increased from 0.79 +/- 0.35 W before surgery to 1.2 +/- 0.5 W after surgery (p =.042). There were statistically significant improvements in all radiographic parameters studied. This is the first prospective study to evaluate the in vivo effects on gait in patients undergoing this common surgical procedure. Analysis demonstrated statistically significant improvement in kinetic and kinematic parameters of gait function.