Biomechanics and Orthotic Treatment of the Adult Acquired Flatfoot

Higher revision rates in patients with preoperative contralateral pes planovalgus deformity following total knee arthroplasty

PURPOSE

The purpose of this study was to compare the incidence of revision in those with pes planovalgus deformity to those without using a large national database. Given the reciprocal changes in lower extremity alignment associated with planovalgus foot deformity, it has been suggested that patients with this deformity has worse outcomes following total knee arthroplasty (TKA).

METHODS

A retrospective cohort analysis of patients undergoing elective TKA was conducted using the PearlDiver database. Patients were stratified into three cohorts: those without pes planovalgus, patients with ipsilateral or bilateral pes planovalgus relative to the TKA, and patients with contralateral pes planovalgus. Patients with prior foot reconstructive surgery were excluded. The cohorts were each matched to those without pes planovalgus. Bivariate analysis was performed comparing 90-day medical complications and 2- and 4-year revisions following TKA. An adjusted number needed to be exposed for one additional person to be harmed (NNEH) was calculated using the adjusted odds ratio (OR) and unexposed event rate.

RESULTS

Following matched analysis, those with contralateral pes planovalgus had similar odds (OR 3.41; 95% CI 0.93-12.54; p = n.s.) for aseptic revision within 2 years but significantly higher odds (OR 3.35; 95% CI 1.08-10.41; p = 0.03) within 4 years when compared to those without a pes planovalgus deformity. Within 4 years, there was no significant difference in the incidence of aseptic revision (p = n.s.) in patients with ipsilateral/bilateral pes planovalgus. No patients in any cohort underwent septic revision within 4 years of TKA.

CONCLUSION

This study found that patients with contralateral pes planovalgus deformity had higher odds of aseptic revision within 4 years following primary TKA in a national database, suggesting that the change in gait kinematics associated with this deformity could possibly be associated with increased revision rates.

LEVEL OF EVIDENCE

Level III.

Surgical Considerations for Revision Flatfoot Reconstruction: Overcorrection/Undercorrection

Reconstructive surgery of the symptomatic pes planus deformity is a very common procedure with relatively good outcomes. Many factors such as patient selection, patient expectations, and surgical execution can influence the results. In addition to achieving osseous union, the overall postoperative alignment is critical in determining functional outcome. Specifically, under- and over-correction respectively present their own unique problems and symptomatology. The purpose of this review is to discuss the adverse outcomes after mal-reduction of flatfoot reconstruction and emphasize the strategies to correct the subsequent deformity.

Injuries to the Spring Ligament: Nonoperative Treatment

The fibrocartilage within the superomedial calcaneonavicular (spring) ligament is part of an interwoven complex of ligaments that span the ankle, subtalar, and talonavicular joints. Acute isolated rupture of the spring ligament has been reported in association with an eversion ankle sprain. Attenuation and failure of the spring ligament causes complex 3D changes called the progressive collapsing foot deformity (PCFD). This deformity is characterized by hindfoot eversion, forefoot supination, collapse of the medial longitudinal arch, and forefoot abduction. Nonoperative treatment of an isolated spring ligament rupture and PCFD using various designs of orthoses have shown promising results.

Biomechanical comparison among five mid/hindfoot arthrodeses procedures in treating flatfoot using a musculoskeletal multibody driven finite element model

BACKGROUND AND OBJECTIVE

Mid/hindfoot arthrodesis could modify the misalignment of adult-acquired flatfoot and attenuate pain. However, the long-term biomechanical effects of these surgical procedures remain unclear, and the quantitative evidence is scarce. Therefore, we aimed to investigate and quantify the influences of five mid/hindfoot arthrodeses on the internal foot biomechanics during walking stance.

METHODS

A young participant with flexible flatfoot was recruited for this study. We reconstructed a subject-specific musculoskeletal multibody driven-finite element (FE) foot model based on the foot magnetic resonance imaging. The severe flatfoot model was developed from the flexible flatfoot through the attenuation of ligaments and the unloading of the posterior tibial muscle. The five mid/hindfoot arthrodeses simulations (subtalar, talonavicular, calcaneocuboid, double, and triple arthrodeses) and a control condition (no arthrodesis) were performed simultaneously in the detailed foot multibody dynamics model and FE model. Muscle forces calculated by a detailed multi-segment foot model and ground reaction force were used to drive the foot FE model. The internal foot loadings were compared among control and these arthrodeses conditions at the first and second vertical ground reaction force (VGRF) peak and VGRF valley instants.

RESULTS

The results indicated that the navicular heights in double and triple arthrodeses were higher than other surgical procedures, while the subtalar arthrodesis had the smallest values. Five mid/hindfoot arthrodeses reduced the peak plantar fascia stress compared to control. However, double and triple arthrodeses increased the peak medial cuneo-navicular joint contact pressures and peak foot pressures as well as the metatarsal bones stresses.

CONCLUSION

Although mid/hindfoot arthrodesis generally reduced the collapse of medial longitudinal arch and plantar fascia loading during the stance phase, the increased loading in the adjacent unfused joint and metatarsal bones for double and triple arthrodeses should be noted. These findings could account for some symptoms experienced by flatfoot patients after surgery, which may facilitate the optimization of surgical protocols.

Progressive Collapsing Foot Deformity. Is There Really a Johnson and Strom Stage I?

Johnson and Strom stage I posterior tibialis tendon dysfunction presents with pain and swelling but preserved function and no deformity. Diagnosis is clinical. Pathomechanics explains the overloading of the tendon that may be worsened by a tight gastrocnemius, but systemic inflammatory disease may also be responsible for a stage I condition. Medial heel wedged orthoses are effective in most patients. Surgery usually consists of an open/endoscopic tenosynovectomy. In cases of complete tendon rupture, flexor digitorum longus tendon transfer may be considered. Stage I patients with a higher risk of progression-inflammatory conditions, excessive laxity, obese-may benefit from a "prophylactic" medializing calcaneal osteotomy.

Podiatrists' views and experiences of using real time clinical gait analysis in the assessment and treatment of posterior tibial tendon dysfunction

Background

Real time clinical gait analysis (RTCGA) is often incorporated as part of a general or lower limb musculoskeletal (MSK) adult patient assessment. However, it is not known if RTCGA is clinically effective as a useful outcome measure or aids in decision making. Whether there is a clinical worth in conducting RTCGA in adult MSK consultations remains controversial. The aim of this study was to provide unique insights into MSK podiatrists use and opinions of RTCGA, using Posterior Tibial Tendon Dysfunction (PTTD) as an exemplar adult condition.

Methods

A qualitative approach was employed to explore MSK podiatrists’ views and experiences of RTCGA when assessing or treating patients with PTTD. Semi-structured interviews were conducted via Skype video calls which were transcribed using an orthographic transcription method. Thematic analysis was employed to identify key meanings and report patterns within the data.

Results

Twenty nine MSK podiatrists who used RTCGA in the assessment and treatment of PTTD participated in the study. Five themes were identified as 1) RTCGA Method; 2) Working with RTCGA; 3) RTCGA uses; 4) What could aid RTCGA; 5) How RTCGA skills are acquired. This is the first known study to explore this topic of relevance to clinicians and researchers alike. Clinical observations were not only kinematic, but also included patient perceived experiences such as pain and orthotic comfort with normative kinematic reference values not perceived as important to that management goal. The most common barefoot RTCGA observations performed were the rearfoot to leg angle, medial bulge, forefoot abduction and arch integrity. However, a high amount of variation in many gait observations was noted between participants. Documentation methods also varied with a four-point scale system to grade motion and position most often employed and RTCGA was most often learnt through experience. The main barriers to performing RTCGA were clinical time and space restrictions.

Conclusion

Findings from this study have provided a view of how podiatry MSK clinicians utilise RTCGA within their practice. MSK podiatrists use RTCGA as both an outcome measure and as an aid in decision making. This implies a perceived worth in conducting RTCGA, however further work is recommended that focusses on development of a national guideline to RTCGA to be adopted.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13047-021-00482-8.

Influence of arch support heights on the internal foot mechanics of flatfoot during walking: A muscle-driven finite element analysis

BACKGROUND

Different arch support heights of the customized foot orthosis could produce different effects on the internal biomechanics of the foot. However, quantitative evidence is scarce. Therefore, we aimed to investigate and quantify the influence of arch support heights on the internal foot biomechanics during walking stance.

METHODS

We reconstructed a foot finite element model from a volunteer with flexible flatfoot. The model enabled a three-dimensional representation of the plantar fascia and its interactions with surrounding osteotendinous structures. The volunteer walked in foot orthosis with different arch heights (low, neutral, and high). Muscle forces during gaits were calculated by a multibody model and used to drive a foot finite element model. The foot contact pressures and plantar fascia strains in different regions were compared among the insole conditions at the first and second vertical ground reaction force (VGRF) peak and VGRF valley instants.

RESULTS

The results indicated that peak foot pressures decreased in balanced standing and second VGRF as the arch support height increased. However, peak midfoot pressures increased during all simulated instants. Meanwhile, high arch support decreased the plantar fascia loading by 5%-15.4% in proximal regions but increased in the middle and distal regions.

CONCLUSION

Although arch support could generally decrease the plantar foot pressure and plantar fascia loading, the excessive arch height may induce high midfoot pressure and loadings at the central portion of the plantar fascia. The consideration of fascia-soft tissue interaction in modeling could improve the prediction of plantar fascia strains towards design optimization for orthoses.

Design and Preliminary Validation of Individual Customized Insole for Adults with Flexible Flatfeet Based on the Plantar Pressure Redistribution

Flatfoot is a common musculoskeletal deformity. One of the most effective treatments is to wear individually customized plantar pressure-based insoles to help users change the abnormally distributed pressure on the pelma. However, most previous studies were divided only into several plantar areas without detailed plantar characteristic analysis. In this study, a new insole is designed which redistributes pressure following the analysis of characteristic points of plantar pressure, and practical evaluation during walking of subjects while wearing the insole. In total, 10 subjects with flexible flatfeet have participated in the performance of gait experiments by wearing flat insoles, orthotic insoles, and plantar pressure redistribution insoles (PPRI). The results showed that the stance time of PPRI was significantly lower than that of the flat insoles under slow gait. PPRI in the second to third metatarsal and medial heel area showed better unloading capabilities than orthotic insoles. In the metatarsal and heel area, the PPRI also had its advantage in percentage of contact area compared to flat insole and orthotic insole. The results prove that PPRI improves the plantar pressure distribution and gait efficiency of adults with flexible flatfeet, and can be applied into clinical application.