Reconstruction operations for acquired flatfoot: biomechanical evaluation

Investigation into the effect of deltoid ligament injury on rotational ankle instability using a three-dimensional ankle finite element model

Background

Injury to the lateral collateral ligament of the ankle may cause ankle instability and, when combined with deltoid ligament (DL) injury, may lead to a more complex situation known as rotational ankle instability (RAI). It is unclear how DL rupture interferes with the mechanical function of an ankle joint with RAI.

Purpose

To study the influence of DL injury on the biomechanical function of the ankle joint.

Methods

A comprehensive finite element model of an ankle joint, incorporating detailed ligaments, was developed from MRI scans of an adult female. A range of ligament injury scenarios were simulated in the ankle joint model, which was then subjected to a static standing load of 300 N and a 1.5 Nm internal and external rotation torque. The analysis focused on comparing the distribution and peak values of von Mises stress in the articular cartilages of both the tibia and talus and measuring the talus rotation angle and contact area of the talocrural joint.

Results

The dimensions and location of insertion points of ligaments in the finite element ankle model were adopted from previous anatomical research and dissection studies. The anterior drawer distance in the finite element model was within 6.5% of the anatomical range, and the talus tilt angle was within 3% of anatomical results. During static standing, a combined rupture of the anterior talofibular ligament (ATFL) and anterior tibiotalar ligament (ATTL) generates new stress concentrations on the talus cartilage, which markedly increases the joint contact area and stress on the cartilage. During static standing with external rotation, the anterior talofibular ligament and anterior tibiotalar ligament ruptured the ankle's rotational angle by 21.8% compared to an intact joint. In contrast, static standing with internal rotation led to a similar increase in stress and a nearly 2.5 times increase in the talus rotational angle.

Conclusion

Injury to the DL altered the stress distribution in the tibiotalar joint and increased the talus rotation angle when subjected to a rotational torque, which may increase the risk of RAI. When treating RAI, it is essential to address not only multi-band DL injuries but also single-band deep DL injuries, especially those affecting the ATTL.

Role of Robotic Gait Simulators in Elucidating Foot and Ankle Pathomechanics

Testing with cadaveric foot and ankle specimens began as mechanical techniques to study foot function and then evolved into static simulations of specific instances of gait, before technologies were eventually developed to fully replicate the gait cycle. This article summarizes the clinical applications of dynamic cadaveric gait simulation, including foot bone kinematics and joint function, muscle function, ligament function, orthopaedic foot and ankle pathologies, and total ankle replacements. The literature was reviewed and an in-depth summary was written in each section to highlight one of the more sophisticated simulators. The limitations of dynamic cadaveric simulation were also reviewed.

Length change pattern of the ankle deltoid ligament during physiological ankle motion

BACKGROUND

Length change pattern of the ankle deltoid ligament during physiological ankle motion is still confused currently and had not been studied in vivo.

METHODS

The deltoid ligaments from 7 cadaveric specimens were dissected. Lengths of each band during 30° plantarflexion to 20° dorsiflexion were measured. A dual fluoroscopy imaging system was utilized to capture the images of hindfoot joint of 7 healthy subjects during the stance phase of walking. 3D bone models were reconstructed from CT images. Lengths of each band were calculated after model-image registration utilizing a solid modeling software. Percentage of length variation and poses when the bands were in maximum extension were documented among each band.

RESULTS

The anterior border of tibiocalcaneal ligament (TCL) had only 1.7% length variation in vitro and 5.7% length variation in vivo. The tibionavicular ligament, tibiospring ligament, and deep anterior tibiotalar ligament were in maximum extension at 30° plantarflexion, however, superficial posterior tibiotalar ligament, deep posterior tibiotalar ligament, and the posterior border of TCL were in maximum extension at 20° dorsiflexion. The tibionavicular ligament, tibiospring ligament, and deep anterior tibiotalar ligament were in maximum extension during foot flat. The TCL was in maximum extension during midstance. The superficial posterior tibiotalar ligament and deep posterior tibiotalar ligament were in maximum extension during heel off and toe off.

CONCLUSION

The length of TCL did not change during ankle dorsiflexion and plantarflexion. The bands anterior to and posterior to the TCL showed different length change pattern during physiological ankle dorsiflexion and plantarflexion.

Clinical Appearance of Medial Ankle Instability

Whereas tenderness, ecchymosis, and swelling over the deltoid ligament have relatively poor sensitivity, resulting valgus and pronation deformity that is seen to disappear when the patient is asked to activate the posterior tibial muscle or to go in tiptoe position is the hallmark for the presence of medial ankle instability. A pain on palpation at anteromedial edge of the ankle confirms the diagnosis. Various stress tests permit to confirm and specify the injury pattern. A pseudo hallux rigidus is the consequence of a hyperactivity of flexor hallucis longus muscle to protect the foot against the valgus and pronation deformity.

Consensus for the Indication of a Medializing Displacement Calcaneal Osteotomy in the Treatment of Progressive Collapsing Foot Deformity

RECOMMENDATION

There is evidence that the medial displacement calcaneal osteotomy (MDCO) can be effective in treating the progressive collapsing foot deformity (PCFD). This juxta-articular osteotomy of the tuberosity shifts the mechanical axis of the calcaneus from a more lateral position to a more medial position, which provides mechanical advantage in the reconstruction for this condition. This also shifts the action of the Achilles tendon medially, which minimizes the everting deforming effect and improves the inversion forces. When isolated hindfoot valgus exists with adequate talonavicular joint coverage (less than 35%-40% uncoverage) and a lack of significant forefoot supination, varus, or abduction, we recommend performing this osteotomy as an isolated bony procedure, with or without additional soft tissue procedures. The clinical goal of the hindfoot valgus correction is to achieve a clinically neutral heel, as defined by a vertical axis from the heel up the longitudinal axis of the Achilles tendon and distal aspect of the leg. The typical range when performing a MDCO, while considering the location and rotation of the osteotomy, is 7 to 15 mm of correction.

LEVEL OF EVIDENCE

Level V, consensus, expert opinion.

Treatment of Stage 4 Flatfoot

Stage 4 flatfoot represents only a small proportion of flatfoot cases and is likely to become even rarer. The evidence base to guide treatment is limited to case series and expert opinion. Therefore, a pragmatic approach to treatment must be taken. Low-demand individuals may manage well with conservative treatment. Surgical management is complex, likely to require staging, and has a significant complication profile. Patients should be fully informed and understanding of this. First principles of surgery should be followed, including restoring hindfoot and ankle joint alignment, appropriate soft tissue balancing, and optimizing function by limiting arthrodeses and subsequent stiffness.

Results of subtalar arthroereisis for posterior tibial tendon dysfunction stage IIA1. Based on 35 patients

BACKGROUND

The aim of the study was to evaluate the clinical and radiological results obtained in the treatment of adult flexible flatfoot secondary to posterior tibial dysfunction with subtalar arthroereisis using a Kalix ^® endorthesis.

METHODS

35 patients (37 feet) were studied, having been operated between January 2010 and January 2015 for reducible flatfoot secondary to posterior tibial tendon dysfunction stage IIA1 of Bluman.

RESULTS

The average follow up was 47.52 months with a minimum of 14 months and a maximum of 75 months. The average age was 54.85, with an age range from 40 to 80 years old. In 74% of cases excellent or good results were obtained, according to our evaluation. The most common complication of this procedure was persistent pain in the sinus tarsi. 35% of cases in this group required implant removal for this reason.

CONCLUSIONS

We believe that arthroereisis is valid for the treatment of flat foot secondary to posterior tibial tendon dysfunction at this stage, giving a high percentage of good and excellent results.

Analysis of 3-dimensional finite element after reconstruction of impaired ankle deltoid ligament

We compared four repair techniques for impaired ankle ligament deltoideum, namely Wiltberger, Deland, Kitaoka and Hintermann using a 3-dimensional finite element. We built an ankle ligament deltoideum model, including six pieces of bone structures, gristles and main ligaments around the ankle. After testing the model, we built an impaired ligament deltoideum model plus four reconstruction models. Subsequently, different levels of force on ankles with different flexion were imposed and ankle biomechanics were compared. In the course of bending, from plantar flexion 20° to back flexion 20°, the extortion of talus decreased while the eversion increased. Four reconstruction models failed to bring back the impaired ankle to normal, with an obvious increase of extortion and eversion. The Kitaoka technique was useful to reduce the extortion angle in a consequential manner. Compared with the other three techniques, the Kitaoka technique produced better results for extortion angle and the difference was statistically significant. However, in case of eversion, there was no significant difference among the four techniques (P>0.05). Lateral ligament's stress in all the four models was different from the normal one. When the ankle was imposed with extortion moment of force, stress of anterior talofibular ligament with the Kitaoka reconstruction method was close to that of the complete deltoid ligament. When ankle was imposed with eversion moment of force, stress of anterior talofibular ligament with Kitaoka and Deland reconstruction methods were close to that of the complete deltoid ligament. We concluded that Kitaoka and Deland tendon reconstruction technique could recover impaired ankle deltoid ligament and re-established its normal biomechanics characteristics.

Reconstruction of superficial deltoid ligaments with allograft tendons in medial ankle instability: A technical report

BACKGROUND

Deltoid ligament insufficiency can cause arthritic changes with various symptoms in the ankle joint. However, reconstruction procedures of the medial collateral and deltoid ligaments have drawn less attention than those of the lateral ankle ligaments. Few techniques for reconstructing deltoid ligaments are available, and those that are can be complex.

OBJECTIVE

We introduce a new surgical method for reconstructing superficial deltoid ligaments that is simple and straightforward.

CONCLUSION

With this method, the tibionavicular and tibiocalcaneal ligaments can be reconstructed efficiently and easily.

Percutaneous Deltoid Ligament Augmentation Using Suture Tape for Medial Ankle Instability

Compared with lateral ankle instability, medial ankle instability has many fewer treatment strategies and fewer reconstructive options available. The best method for deltoid ligament reconstruction remains unclear. Percutaneous deltoid ligament augmentation using suture tape represents a novel alternative technique for chronic medial ankle instability.

Radiographic Identification of the Deltoid Ligament Complex of the Medial Ankle

BACKGROUND

An injury to the deltoid ligament complex of the ankle can require surgical intervention in cases of chronic instability. There is an absence of data describing medial ankle ligament anatomy on standard radiographic views.

PURPOSE

To quantitatively describe the anatomic origins and insertions of the individual ligamentous bands of the superficial and deep deltoid on standard lateral and mortise radiographic views with reference to osseous landmarks and anatomic axes.

STUDY DESIGN

Descriptive laboratory study.

METHODS

Twelve nonpaired, fresh-frozen cadaveric foot and ankle specimens were utilized. Specimens were dissected free of all overlying soft tissue to identify individual ligamentous bands of the superficial and deep deltoid ligaments and to isolate their distinct origins and insertions. Footprint centers were identified on standard lateral and mortise radiographs by 2-mm stainless steel spheres embedded at the level of the cortical bone. Distances to osseous landmarks were measured independently by 2 blinded reviewers to calculate mean distances and evaluate reliability and repeatability measures using intraclass correlation coefficients.

RESULTS

Varying subsets of the 4 superficial deltoid bands including the tibionavicular (12/12), tibiospring (12/12), tibiocalcaneal (9/12), and superficial posterior tibiotalar (9/12) ligaments were found across specimens. On the lateral view, the tibionavicular ligament was the most anterior and attached 7.6 ± 1.9 mm superior and anterior to the inferior tip of the medial malleolus. The tibiospring ligament attached 12.1 ± 2.2 mm superior and anterior to the inferior tip of the medial malleolus and attached to the spring ligament, which coursed from its origin 12.3 ± 1.6 mm anterior and slightly inferior to the posterior point of the sustentaculum tali to its insertion on the navicular tuberosity. The tibiocalcaneal ligament and superficial posterior tibiotalar ligament were found posteriorly in the majority of specimens. Two constituents of the deep deltoid, including the deep anterior tibiotalar (11/12) and deep posterior tibiotalar (12/12) ligaments, were found in the majority of specimens. The deep posterior was larger and coursed from the tibia, 8.1 ± 2.2 mm posterior and superior to the inferior tip of the medial malleolus, to its attachment on the talus, 15.5 ± 2.4 mm superior and anterior to the posterior inferior point of the talus on the lateral view.

CONCLUSION

Quantitative radiographic relationships describing the anatomic origins and insertions of the individual superficial and deep deltoid constituents were defined with excellent reliability and reproducibility.

CLINICAL RELEVANCE

Radiographic parameters will augment current anatomic data by assisting with preoperative planning, intraoperative guidance, and postoperative assessment. These radiographic guidelines will facilitate the development of novel anatomic reconstructions and allow surgeons to plan the locations of reconstruction tunnels.

Treatment of Stage II Adult Acquired Flatfoot Deformity With Subtalar Arthroereises

The role of arthroereises in the treatment of adult acquired flatfoot deformity (AAFD) has been controversial. This study aims to evaluate the outcome of subtalar arthroereisis in treating stage II AAFD. A total of 24 feet with stage II AAFD were treated surgically between 2009 and 2011 using subtalar arthroereisis. The average follow-up was 29.7 months (range = 24 to 35 months). The average postoperative AOFAS (American Orthopaedic Foot and Ankle Society) Ankle-Hindfoot Scale score was 85.6 (compared with 51.7 preoperatively). Average preoperative talar-first metatarsal angle and talonavicular coverage angle were -13.9° and 38.3°, respectively. The average postoperative angles were 1.6° and 11.2°, respectively (P < .01). No deformity recurrences were found at the time of last follow-up, with the exception of 1 case. Subtalar arthroereisis appears to be a reasonable treatment option for stage IIA and IIC AAFD. It can be used alone to correct mild hindfoot valgus, and it can also be performed with a calcaneal osteotomy to gain more correction in severe stage II AAFD.

LEVELS OF EVIDENCE

Therapeutic, Level IV: Retrospective Case Series.

Technical tips: reconstruction of deep and superficial deltoid ligaments by peroneus longus tendon in stage 4 posterior tibial tendon dysfunction

The deltoid ligament is composed of the superficial and deep layers. Disruption of the deltoid ligament can occur in rotational ankle fracture, chronic ankle instability, or stage 4 posterior tibial tendon dysfunction. Correcting valgus tilt at the time of flatfoot reconstruction in case of stage 4 posterior tibial tendon dysfunction may prevent future collapse and the need for ankle arthrodesis or possibly ankle arthroplasty. We describe a technique of reconstruction of both the superficial and deep deltoid ligaments by peroneus longus tendon.

Calcaneal "Z" osteotomy effect on hindfoot varus after triple arthrodesis in a cadaver model

BACKGROUND

Triple arthrodesis involves subtalar, talonavicular, and calcaneocuboid joint fusion and is performed to relieve pain and correct deformity. Complications include malunion resulting in equinovarus and lateral column overload, which can lead to painful callosities and stress fractures. This study quantified the effectiveness of a closing-wedge calcaneal "Z" osteotomy for correction of the varus condition and reduction of abnormal loading of the lateral border of the foot.

METHODS

Ten fresh-frozen feet were used. Angle meters were attached to the calcaneus and second cuneiform to measure hindfoot and midfoot varus, and pressure sensors were placed under the first and fifth metatarsal heads to document loading of the borders of the foot. Tensile loads were applied to ten extrinsic tendons and the Achilles tendon while an 1187 N axial foot load was applied. Calcaneus and second cuneiform coronal plane angles and medial and lateral plantar pressures were measured initially, after triple fusion-induced varus, and after "Z" osteotomy.

RESULTS

The calcaneal "Z" osteotomy had no significant corrective effect, with hindfoot alignment virtually identical before and after the procedure under the described foot loading conditions. Similarly, second cuneiform inclination, representative of midfoot alignment, showed no change from the osteotomy. Medial and lateral peak plantar pressures after calcaneal "Z" osteotomy did not differ from those measured after varus triple fusion.

CONCLUSION

In this cadaver model of varus malunited triple arthrodesis, the closing-wedge calcaneal "Z" osteotomy was ineffective for correction of bone alignment and lateral forefoot overloading under the tested conditions.

CLINICAL RELEVANCE

The results provide additional information on which to base treatment after triple arthrodesis with varus malunion.

Reverse Evans peroneus brevis medial ankle stabilization for balancing valgus ankle contracture during total ankle replacement

Medial ankle instability secondary to deltoid ligament insufficiency is frequently encountered when performing total ankle replacement and remains a challenge. In the present techniques report, we describe a "reverse" Evans peroneus brevis tendon nonanatomic deltoid ligament reconstruction for medial ankle stabilization harvested through limited incisions using simple topographic anatomic landmarks. The harvested peroneus brevis tendon is brought through a drill hole in the talus from laterally to medially, aiming for the junction of the talar neck and body plantar to the midline. The tendon is the brought superiorly and obliquely to the anterior medial aspect of the distal tibia where it is secured under a plate and screw construct. This modified Evans peroneus brevis tendon nonanatomic deltoid ligament reconstruction is useful in providing medial ankle stability during or after primary and revision total ankle replacement.

The ligament anatomy of the deltoid complex of the ankle: a qualitative and quantitative anatomical study

BACKGROUND

The deltoid ligament has both superficial and deep layers and consists of up to six ligamentous bands. The prevalence of the individual bands is variable, and no consensus as to which bands are constant or variable exists. Although other studies have looked at the variance in the deltoid anatomy, none have quantified the distance to relevant osseous landmarks.

METHODS

The deltoid ligaments from fourteen non-paired, fresh-frozen cadaveric specimens were isolated and the ligamentous bands were identified. The lengths, footprint areas, orientations, and distances from relevant osseous landmarks were measured with a three-dimensional coordinate measurement device.

RESULTS

In all specimens, the tibionavicular, tibiospring, and deep posterior tibiotalar ligaments were identified. Three additional bands were variable in our specimen cohort: the tibiocalcaneal, superficial posterior tibiotalar, and deep anterior tibiotalar ligaments. The deep posterior tibiotalar ligament was the largest band of the deltoid ligament. The origins from the distal center of the intercollicular groove were 16.1 mm (95% confidence interval, 14.7 to 17.5 mm) for the tibionavicular ligament, 13.1 mm (95% confidence interval, 11.1 to 15.1 mm) for the tibiospring ligament, and 7.6 mm (95% confidence interval, 6.7 to 8.5 mm) for the deep posterior tibiotalar ligament. Relevant to other pertinent osseous landmarks, the tibionavicular ligament inserted at 9.7 mm (95% confidence interval, 8.4 to 11.0 mm) from the tuberosity of the navicular, the tibiospring inserted at 35% (95% confidence interval, 33.4% to 36.6%) of the spring ligament's posteroanterior distance, and the deep posterior tibiotalar ligament inserted at 17.8 mm (95% confidence interval, 16.3 to 19.3 mm) from the posteromedial talar tubercle.

CONCLUSIONS

The tibionavicular, tibiospring, and deep posterior tibiotalar ligament bands were constant components of the deltoid ligament. The deep posterior tibiotalar ligament was the largest band of the deltoid ligament.

CLINICAL RELEVANCE

The anatomical data regarding the deltoid ligament bands in this study will help to guide anatomical placement of repairs and reconstructions for deltoid ligament injury or instability.

Biomechanical assessment of flexible flatfoot correction: comparison of techniques in a cadaver model

BACKGROUND

Options for surgical correction of acquired flexible flatfoot deformity involve bone and soft-tissue reconstruction. We used an advanced cadaver model to evaluate the ability of key surgical procedures to correct the deformity and to resist subsequent loss of correction.

METHODS

Stage-IIB flatfoot deformity was created in ten cadaver feet through ligament sectioning and repetitive loading. Six corrective procedures were evaluated: (1) lateral column lengthening, (2) medial displacement calcaneal osteotomy with flexor digitorum longus transfer, (3) Treatment 2 plus lateral column lengthening, (4) Treatment 3 plus "pants-over-vest" spring ligament repair, (5) Treatment 3 plus spring ligament repair with use of the distal posterior tibialis stump, and (6) Treatment 3 plus spring ligament repair with suture and anchor. Correction of metatarsal dorsiflexion and of navicular eversion were quantified initially and periodically during postoperative cyclic loading.

RESULTS

Metatarsal dorsiflexion induced by arch flattening was initially corrected by 5.5° to 10.6°, depending on the procedure. Navicular eversion was initially reduced by 2.1° to 7.7°. The correction afforded by Treatments 1, 3, 4, 5, and 6 exceeded that of Treatment 2 initially and throughout postoperative loading. Inclusion of spring ligament repair did not significantly enhance correction.

CONCLUSIONS

Under the tested conditions, medial displacement calcaneal osteotomy with flexor digitorum longus tendon transfer was inferior to the other evaluated treatments for stage-IIB deformity. Procedures incorporating lateral column lengthening provided the most sagittal and coronal midfoot deformity correction. Addition of spring ligament repair to a combination of these three procedures did not substantially improve correction.

CLINICAL RELEVANCE

An understanding of treatment effectiveness is essential for optimizing operative management of symptomatic flatfoot deformity. This study provides empirical evidence of the advantage of lateral column lengthening and novel information on resistance to postoperative loss of correction.

Tibialis posterior tendon and deltoid and spring ligament injuries in the elite athlete

The tibialis posterior tendon and the spring and deltoid ligament complexes combine to provide dynamic and passive stabilization on the medial side of the ankle and hindfoot. Some of the injuries will involve acute injury to previous healthy structures, but many will develop insidiously. The clinician must be aware of new treatment strategies and the level of accompanying scientific evidence regarding injuries sustained by athletes in these areas, while acknowledging that more traditional management applied to nonathletic patients is still likely to be appropriate in the setting of treatment for elite athletes.

Biomechanical evaluation of tenodesis reconstruction in ankle with deltoid ligament deficiency: a finite element analysis

PURPOSE

Isolated deltoid ligament injuries are relatively uncommon but can be a significant source of pain and disability. Several approaches to deltoid reconstruction have been reported. However, there is no previous comparative study of Wiltberger, Deland, Kitaoka and Hintermann procedures with respect to biomechanical characteristics such as kinematics, ligaments and grafts stresses using finite element analysis. The purpose of this study was to evaluate the biomechanical results of those deltoid ligament reconstructions using finite element analysis.

METHODS

A three-dimensional finite element model of the ankle including six bony structures, cartilage and nine principal ligaments surrounding the ankle joint complex was developed and validated. In addition to the intact model, superficial deltoid-deficient, deltoid-deficient, Wiltberger reconstruction, Deland reconstruction, Kitaoka reconstruction and Hintermann reconstruction models were simulated. Then, the forces in the ligaments and grafts and the kinematics of talus and calcaneus were predicted for an eversional or external torque through the range of ankle flexion.

RESULTS

No reconstructions could completely restore the values for ankle flexibility and the stresses of the lateral ligaments to normality. The Kitaoka procedure was the most effective technique in eliminating external rotation displacement. The Deland procedure restored better the talar tilt than the other three reconstructions.

CONCLUSION

This study showed that Kitaoka and Deland procedures have advantages with regard to rotational stabilities as well as ligaments stress in comparison with other methods.

Tendon transfer options in managing the adult flexible flatfoot

Patients undergoing surgery for posterior tibial tendon dysfunction may require tendon transfer. The flexor digitorum longus is most commonly transferred, although the flexor hallucis longus and peroneus brevis have also been described in the literature. This article discusses the advantages and disadvantages of the different tendons, the surgical techniques used to perform them, and their results in the literature, concentrating principally on studies in which additional bone procedures were not performed. This article will also discuss the potential role for isolated soft tissue procedures in the treatment of stage 2 posterior tibial tendon dysfunction.

Is there a role for subtalar arthroereisis in the management of adult acquired flatfoot?

Subtalar arthroereisis, often combined with Achilles tendon lengthening, is a simple and effective way to treat flexible flatfoot in adults. The most common complication is pain in sinus tarsi, which usually disappears after removal of the implant. Midterm results are good and it does not hinder other treatments in the future.

Calcaneal osteotomy in the treatment of adult acquired flatfoot deformity

Calcaneal osteotomies are an essential part of our current armamentarium in the treatment of AAFD. Soft tissue correction or bony realignment alone have failed to adequately correct the deformity; therefore, both procedures are used simultaneously to achieve long-term correction. Medial displacement and lateral column lengthening osteotomies in isolation or in combination and the Malerba osteotomy have been employed along with soft tissue balancing to good effect by various authors. The goal is to create a stable bony configuration with adequate soft tissue balance to maintain dynamic equilibrium in the hindfoot. In “pronatory syndromes,” the relation of the osteotomy to the posterior subtalar facet modifies the biomechanics of the hindfoot in different ways. Anterior calcaneal osteotomies correct deformities in the transverse plane (forefoot abduction), whereas posterior tuberosity osteotomies result in “varization” of the calcaneus and correct the frontal plane deformity. The choice of osteotomy depends on the plane of the dominant deformity. If the subtalar axis is more horizontal than normal, transverse plane movement is cancelled out and the frontal plane eversion–inversion is predominant. The patient presents with marked hindfoot valgus without significant forefoot abduction. Conversely, if the subtalar axis is more vertical than normal, transverse plane movement is predominant and the patient presents with forefoot abduction and instability of the medial midtarsal joints, although without significant hindfoot valgus. In this situation, a lateral column lengthening procedure is recommended to decrease the uncovering of the talar head and improve the height of the arch while correcting the forefoot abduction. With a predominant frontal plane deformity, medialization of the calcaneal tuberosity is used to displace the calcaneal weight bearing axis medially, aligning it with the tibial axis and restoring the function of the gastrosoleus as a heel invertor. An essential prerequisite for this is the absence of arthritis affecting the subtalar joint. The Achilles tendon may need to be lengthened at the same time.

Update on stage IV acquired adult flatfoot disorder: when the deltoid ligament becomes dysfunctional

Deltoid ligament complex insufficiency is a fundamental pathologic component of stage IV AAFD. Failure of the deltoid ligament allows the talus to tilt into valgus within the ankle mortise. If left untreated, ankle joint biomechanics are altered and may lead to debilitating tibiotalar arthritis. All surgical treatments that address the valgus talar tilt seen with stage IV AAFD require accompanying procedures to properly realign the hindfoot. Stage IV AAFD can be subdivided into two groups. Patients with a flexible ankle deformity without advanced tibiotalar arthritis (stage IV-A) can be considered for a joint-sparing procedure. A variety of procedures have been described, but longterm follow-up studies have yet to determine which of these techniques is optimal. Patients with a rigid valgus ankle deformity or a flexible deformity accompanied by advanced tibiotalar arthritis (stage IV-B) should be considered for a joint-sacrificing procedure. To date, the most reliable results for stage IV-B AAFD have been reported with either tibiotalocalcaneal or pan-talar arthrodesis.

[Problems in complex hindfoot corrections]

This article discusses the intraoperative and postoperative problems seen in the treatment of posterior tibial tendon dysfunction. Problems associated with tendon transposition procedures, osteotomy and arthrodesis are discussed. The preoperative, intraoperative and postoperative problems and complications and how to avoid or treat them will be addressed. The individual procedures are often part of other complex hindfoot reconstructions. For this reason the general and special aspects of treating posterior tibial dysfunction can often be transferred to avoiding and resolving problems in hindfoot surgery.

Minimally invasive deltoid ligament reconstruction for stage IV flatfoot deformity

BACKGROUND

Stage IV is the most advanced form of acquired adult flatfoot deformity (AAFD). It is present when valgus tibiotalar angulation occurs with foot deformities associated with AAFD. Tibiotalocalcaneal or pantalar fusion has been the gold standard for treatment of Stage IV AAFD. However, in some of these patients the tibiotalar deformity is correctable. We sought to determine whether minimally invasive deltoid ligament reconstruction in conjunction with triple arthrodesis (MIDLR/Triple) allows tibiotalar joint sparing surgical therapy in Stage IV-A AAFD patients.

MATERIALS AND METHODS

Patients diagnosed with Stage IV-A AAFD were given the option of undergoing ankle joint sparing surgery with the MIDLR/Triple technique. Those that chose this option were followed longitudinally. Eight patients underwent the ankle joint sparing procedure. Average followup was 36 months. Radiographic and functional outcome measures were obtained. Success was defined as maintenance of 3 degrees or less of valgus tibiotalar angulation and greater than 2 mm of lateral joint space remaining at final followup.

RESULTS

At final followup, five were judged to have a successful outcome. In those, tibiotalar valgus angulation was reduced from 6.4±2.9 degrees to 2.0±2.0 degrees, lateral ankle joint space was maintained at preoperative levels and SF-12 functional scores were equal to age matched normative scores. The only parameter found to be predictive of successful outcome was the magnitude of preoperative tibiotalar tilt.

CONCLUSIONS

MIDLR/triple is a new treatment option that requires significant care in patient selection and surgical execution. It is a choice that allows for preservation of ankle motion in patients diagnosed with Stage IV-A AAFD who have less than 10 degrees of valgus tibiotalar tilt on preoperative standing ankle radiographs.

Tendon disorders of the foot and ankle, part 3: the posterior tibial tendon

This article provides a review of posterior tibial tendon pathology and the authors' preferred management. The tibialis posterior musculotendinous unit is the most powerful inverter of the foot and an important dynamic stabilizer of the arch. In the stance phase of the gait cycle, it serves as an initiator of both ankle plantar flexion and subtalar inversion. This creates a rigid midfoot by stabilizing the transverse tarsal joint, and allows for increased power generation by the gastrocsoleus complex through toe-off. Injuries to the posterior tibialis tendon include traumatic laceration and dislocation, as well as tenosynovitis and tendinopathy, which can lead to attenuation and rupture. If these injuries are not addressed, significant clinical deformity and disability can result.

A comparison in the muscle activity of the abductor hallucis and the medial longitudinal arch angle during toe curl and short foot exercises

OBJECTIVE

To compare the muscle activity of the abductor hallucis (AbdH) and the medial longitudinal arch (MLA) angle during toe curl (TC) and short foot (SF) exercises while sitting or in one-leg standing position.

DESIGN

Two-way repeated-measures ANOVA was used to analyze the effects of exercise type and position on the muscle activity of the AbdH and the MLA angle.

PARTICIPANTS

Twenty subjects with normal feet participated in this study.

MAIN OUTCOME MEASURES

The muscle activity of the AbdH and the MLA angle were measured during TC and SF exercises while sitting or in one-leg standing position.

RESULTS

The EMG activity of AbdH in SF exercise was significantly greater than during TC exercise in both exercise postural positions (p < 0.001). During the SF exercise, the EMG activity of the AbdH in the one-leg standing position was significantly higher than that while sitting (p < 0.001). The MLA angle in SF exercise was significantly smaller than during TC exercise in both postural positions (p < 0.001).

CONCLUSIONS

These results suggest that SF exercise is a more useful strengthening exercise than TC exercise in activating the AbdH muscle.

Deltoid ligament reconstruction with peroneus longus autograft in flatfoot deformity

BACKGROUND

Stage IV posterior tibial tendon insufficiency is characterized by the presence of valgus talar tilt in the setting of a flatfoot deformity which results from attenuation of the deltoid ligament. Correcting valgus tilt at the time of flatfoot reconstruction may prevent future collapse and the need for joint sacrificing procedures. The purpose of this study was to report the intermediate-term results of patients who underwent deltoid ligament reconstruction using a peroneus longus tendon transfer.

MATERIALS AND METHODS

Five patients (mean age, 67 years ± 5.3 years) who underwent flatfoot reconstruction along with deltoid ligament reconstruction using a peroneus longus autograft were evaluated at a mean of 8.9 ± 1.7 years after surgery. The FAOS, SF-36v2, and VAS surveys were administered. The correction of valgus talar tilt was determined with weightbearing radiographs of the ankle. Ankle range of motion along with standing hindfoot alignment was assessed.

RESULTS

The postoperative average FAOS and SF-36v2 were 68.3 (range, 55.2 to 85.0) and 75.7 (range, 40 to 92), respectively. The valgus talar tilt improved from 7.7 degrees preoperatively to 2.1 degrees postoperatively. Mean ankle range of motion was 47 degrees (range, 40 degrees to 55 degrees). Mean hindfoot alignment was 4 degrees valgus (range, 1 degree varus to 8 degrees valgus).

CONCLUSION

Deltoid ligament reconstruction using a peroneus longus tendon transfer was a useful technique for reducing tibiotalar tilt in the setting of stage IV flatfoot deformity. Correction and function were maintained at intermediate-term followup.

Effects of foot orthoses on the work of friction of the posterior tibial tendon

BACKGROUND

Posterior tibial tendon dysfunction is a significant contributor to flatfeet. Non-operative treatments, like in-shoe orthoses, have varying degrees of success. This study examined changes to the work of friction of the posterior tibial tendon under three conditions: intact, simulated flatfoot, and flatfoot with an orthosis. It was hypothesized that work of friction of the posterior tibial tendon would significantly increase in the flatfoot, yet return to normal with an orthosis. Changes to bone orientation were also expected.

METHODS

Six lower limb cadavers were mounted in a foot simulator, that applied axial and a posterior tibial tendon load. Posterior tibial tendon excursion, gliding resistance, and foot kinematics were monitored, and work of friction calculated. Each specimen moved through a range of motion in the coronal, transverse, and sagittal planes.

FINDINGS

Mean work of friction during motion in the coronal plane were 0.17 N cm (SD 0.07 N cm), 0.25 N cm (SD 0.09 N cm), and 0.23 N cm (SD 0.09 N cm) for the intact, flatfoot, and orthosis conditions, respectively. Motion in the transverse plane yielded average WoF of 0.36 N cm (SD 0.28 N cm), 0.64 N cm (SD 0.25 N cm), and 0.57 N cm (SD 0.38 N cm) in the same three conditions, respectively. The average tibio-calcaneal and tibio-metatarsal valgus angles significantly increased in the flatfoot condition (5.8 degrees and 9 degrees , respectively). However, the orthosis did slightly correct this angle.

INTERPRETATION

The prefabricated orthosis did not consistently restore normal work of friction, though it did correct the flatfoot visually. This implies that patients with flatfeet may be predisposed to developing posterior tibial tendon dysfunction due to abnormal gliding resistance, though bone orientations are restored.

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.

Fatigue of the plantar intrinsic foot muscles increases navicular drop

Our purpose was to assess the effect of foot intrinsic muscle fatigue on pronation, as assessed with navicular drop, during static stance. Twenty-one healthy young adults participated. Navicular drop was measured before and after fatiguing exercise of the plantar foot intrinsic muscles. Surface electromyography of the abductor hallucis muscle was recorded during maximum voluntary isometric contractions (MVIC) in order to find the baseline median frequency (MedF). Subjects then performed sets of 75 repetitions of isotonic flexion contractions of the intrinsic foot muscles against a 4.55 kg weight on a custom pulley system. After each set an MVIC was performed to track shifts in MedF. After a MedF shift of at least 10%, navicular drop measurements were repeated. Subjects exhibited 10.0+/-3.8mm of navicular drop at baseline and 11.8+/-3.8mm after fatigue (p<0.0005). The change in navicular drop was significantly correlated with change in MedF (r=.47, p=.03). The intrinsic foot muscles play a role in support of the medial longitudinal arch in static stance. Disrupting the function of these muscles through fatigue resulted in an increase in pronation as assessed by navicular drop.

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.

The effect of flatfoot deformity and tendon loading on the work of friction measured in the posterior tibial tendon

BACKGROUND

There is limited information regarding the mechanical factors contributing to the progression of posterior tibial tendon dysfunction. Therefore, an investigation of the mechanical forces on the posterior tibial tendon may improve our understanding of this pathology.

METHODS

The gliding resistance and excursion of the posterior tibial tendon in the retromalleolar region was measured in seven cadaveric lower limbs in the coronal, transverse, and sagittal planes. These data were used to calculate the work of friction and to characterize the effect of different tendon loading levels (0.5, 1.0, and 2.0 kg) in the intact and flatfoot conditions.

FINDINGS

Flatfoot deformity significantly increased the excursion of the posterior tibial tendon (P<0.05), increased forefoot and hindfoot range of motion in the coronal and transverse planes (P<0.05) and the work of friction in the coronal and transverse planes (P<0.05), but not in the sagittal plane. There was a significant increase in the work of friction between 0.5 and 2 kg (P<0.05) in all three planes of motion.

INTERPRETATION

The motions in the coronal and transverse planes have a greater effect on the work of friction of the posterior tibial tendon than sagittal plane motion in the flatfoot condition. This study suggests that aggressive treatment of early stage PTT dysfunction with bracing designed to limit coronal and transverse motions, while permitting sagittal motion should be investigated further. Such bracing may decrease the potential of progressive deformity while allowing for more normal ambulation.

Posterior tibial tendon rupture: a refined classification system

Since Johnson's and Strom's classification system in 1989 an increasingly complex array of deformities of the foot has been recognized in association with PTTR. This wide spectrum of deformity is not completely addressed by the current classification system, nor does it leave sufficient room for variation within a given treatment stage. Taking into account ankle and hindfoot valgus, forefoot supination, forefoot abduction, and medial column instability we present and discuss a refined classification for PTTR. Potential treatments for each stage are provided.

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.

Gliding resistance of the posterior tibial tendon

BACKGROUND

Abnormal gliding of the posterior tibial tendon may lead to mechanical trauma, degeneration, and eventually posterior tibial tendon dysfunction. Our study analyzed the gliding resistance of the posterior tibial tendon in intact feet and in feet with simulated flatfoot deformity.

METHODS

An experimental system was developed that allowed direct measurement of gliding resistance at the tendon-sheath interface. Seven normal fresh-frozen cadaver foot specimens were studied, and gliding resistance between the posterior tibial tendon and sheath was measured. The effects of ankle and hindfoot position and the effect of flatfoot deformity on gliding resistance were analyzed. Gliding resistance was measured for 4.9 N applied load to the tendon.

RESULTS

Mean gliding resistance for the neutral position was 77 +/- 13.1 (x10(-2) N). Compared to neutral position, dorsiflexion increased gliding resistance and averaged 130 +/- 38.9 (x10(-2) N), and plantarflexion decreased gliding resistance and averaged 35 +/- 12.6 (x10(-2) N). Flatfoot deformity increased gliding resistance compared to normal feet, averaging 104 +/- 17.0 (x10(-2) N) for neutral, 205 +/- 55.0 (x10(-2) N) for dorsiflexion, and 58 +/- 21.3 (x10(-2) N) for plantarflexion.

CONCLUSIONS

The findings indicate that patients with a preexisting flatfoot deformity may be predisposed to develop posterior tibial tendon dysfunction because of increased gliding resistance and trauma to the tendon surface.

Reconstruction of the chronically failed deltoid ligament: a new technique

BACKGROUND

Chronic deltoid ligament insufficiency that results in valgus tilt of the talus within the ankle mortise (stage IV adult acquired flatfoot) represents a difficult and so far unsolved problem in foot and ankle surgery. If left uncorrected, the deltoid failure with malalignment predisposes to early ankle arthritis and the need for ankle arthrodesis or possibly ankle arthroplasty.

METHODS

Five consecutive patients with deltoid ligament insufficiency resulting in a valgus tilt were treated with a deltoid reconstruction. Reconstruction of the deltoid ligament was done by passing a peroneus longus tendon graft through a bone tunnel in the talus from lateral to medial and then through a second tunnel from the tip of the medial malleolus to the lateral tibia.

RESULTS

At a minimum 2-year followup, all patients had correction of the talar tilt. One patient had 9 degrees of valgus tilt remaining compared to 15 degrees preoperatively, and the procedure was considered a failure. The remaining four patients had correction of the valgus tilt to 4 degrees or less.

CONCLUSION

Although not uniformly successful, deltoid ligament reconstruction using a tendon graft through appropriate bone tunnels can reconstruct the deltoid ligament and correct the valgus talar tilt. Successful results were achieved when combined with correction of flatfoot deformity, which is considered a necessary part of the procedure.

The talonavicular and calcaneocuboid joints: anatomy, biomechanics, and clinical management of the transverse tarsal joint

The transverse tarsal plays a critical role in allowing the foot to transition from a flexible structure that dissipates impact as the foot strikes the ground and accepts the body's weight to the rigid structure that is required for efficient propulsion during toe off.Similarly, the medial longitudinal arch of the foot is controlled by the supportive structures of the talonavicular joint. A fine balance exists between muscular control and static support structures of the talonavicular joint. Failure of one support structure is often followed by fatigue of the remaining support and loss of function of the entire joint complex. This article describes the osseous and ligamentous anatomy of the talonavicular and calcaneocuboid joints and describes the biomechanical role of the transverse tarsal joint in standing and gait. Biomechanical principles are used to illustrate orthotic management of diseases that affect the transverse tarsal joint.

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.

Soft tissue procedures

Soft tissue procedures for PTT dysfunction and adult acquired flat foot improve function and preserve joint motion. These procedures can only be applied to patients who have correctable deformities. The durability of these procedures, without the addition of bone realignment procedures, has been questioned and needs to be investigated further. Reconstruction of the spring ligament complex corrects the flat foot in cadavers but has not been studied clinically. There is still much to be learned in this condition so we are able to provide optimal care for our patients.

Issues relating to failure in the treatment of posterior tibial tendon dysfunction

As our understanding of the underlying cause of flat foot progression improves so will our understanding of how best to catalog and treat the instabilities that are seen. Determining the failure of one type of treatment will be difficult until we can better define the varied pathology and give the treatment methods sufficient time to prove or disprove their premise. If an underlying systemic disease, where either unreliable motor function or unstable ligament support is present, joint arthrodeses are the preferred method of treatment. It is important not to fuse in situ, but rather effect the complete realignment of the foot through the fused joints. At a minimum, I believe that the subtalar fusion is the most appropriate method for gaining a stable correction. Any more stability will warrant a triple arthrodesis. Treatment for the diseased tendon should also be addressed appropriately. Tendon reconstruction alone provides no assurance of weight-bearing deformity correction or lasting function for most patients who have isolated type 2 dysfunction and should be avoided as a stand-alone procedure. It still serves a vital purpose in restoring function to the foot, and, combined with other procedures, aids in the preservation of dynamic response to weight-bearing loads. The choice of adjunctive procedures should be based on the pathology present. Each of the treatment regimens that is discussed in this article has a place in the overall treatment of the clinical disease but none, by itself, seems to correct all of the presentations that are possible for this pathologic entity. The possible exception may be the use of a subtalar realignment and fusion, but this may be overkill in many mild to moderate deformities. Care should be taken in choosing the proper treatment based on the pathology that is presented by each patient.