The relationship between ankle, hindfoot, and forefoot position and posterior tibial muscle excursion

A Cadaveric Limb Analysis of the Posterior Tibial Musculotendinous Junction to determine the feasibility of Interosseous Membrane Tendon Transfer

The transfer of the posterior tibial tendon through the interosseous membrane is potentially an effective treatment to correct the deformity of the foot and ankle. Our study aimed to evaluate the anatomical feasibility of anterior transfer of the posterior tibial tendon through the interosseous membrane route using the musculotendinous junction (MTJ). Eighteen adult cadavers were used. The width and thickness of the tibial posterior MTJ, width of the interosseous membrane at the corresponding level, and the window size of the interosseous membrane were measured. Additionally, the distance between the distal end of the MTJ and the tip of the medial malleolus were recorded. The mean length of the posterior tibial tendon was 83.60 mm, the mean distance of the posterior tibial MTJ to medial malleolus tip was 45.48 mm and the mean length of MTJ was 31.74 mm. The mean width of distal end of MTJ was 7.76 mm, thickness of distal end of MTJ was 4.07 mm and the mean width of the interosseous membrane at the distal end of MTJ was 4.76 mm. We found the mean width of the proximal end of MTJ was 20.68 mm, the mean thickness of proximal end of MTJ was 5.52 mm, and mean width of interosseous membrane at the proximal end of MTJ was 8.76 mm. Our study has demonstrated that a 31 mm length incision made at approximately 45 mm from the proximal end of the medial malleolus can safely reach the MTJ. We recommend an opening length of the interosseous membrane of at least 20 mm.

A Three-Dimensional Printed Foot Orthosis for Flexible Flatfoot: An Exploratory Biomechanical Study on Arch Support Reinforcement and Undercut

The advancement of 3D printing and scanning technology enables the digitalization and customization of foot orthosis with better accuracy. However, customized insoles require rectification to direct control and/or correct foot deformity, particularly flatfoot. In this exploratory study, we aimed at two design rectification features (arch stiffness and arch height) using three sets of customized 3D-printed arch support insoles (R+U+, R+U-, and R-U+). The arch support stiffness could be with or without reinforcement (R+/-) and the arch height may or may not have an additional elevation, undercutting (U+/-), which were compared to the control (no insole). Ten collegiate participants (four males and six females) with flexible flatfoot were recruited for gait analysis on foot kinematics, vertical ground reaction force, and plantar pressure parameters. A randomized crossover trial was conducted on the four conditions and analyzed using the Friedman test with pairwise Wilcoxon signed-rank test. Compared to the control, there were significant increases in peak ankle dorsiflexion and peak pressure at the medial midfoot region, accompanied by a significant reduction in peak pressure at the hindfoot region for the insole conditions. In addition, the insoles tended to control hindfoot eversion and forefoot abduction though the effects were not significant. An insole with stronger support features (R+U+) did not necessarily produce more favorable outcomes, probably due to over-cutting or impingement. The outcome of this study provides additional data to assist the design rectification process. Future studies should consider a larger sample size with stratified flatfoot features and covariating ankle flexibility while incorporating more design features, particularly medial insole postings.

Outcomes Following Revision Surgery After Failed Kidner Procedure for Painful Accessory Navicular

BACKGROUND

The Kidner procedure is performed to treat painful accessory navicular syndrome, with varying results. Recurrent pain remains a complication, and to date, there is a paucity of literature regarding the causes of recurrent pain and surgical outcomes of revision.

METHODS

Twenty-one patients who underwent revision surgery for recurrent pain after the Kidner procedure were identified. All patients had their tendon inspected and treated, and all had a medial displacement calcaneal osteotomy. Revision was indicated after 6 months of failed conservative therapy. Pre- and postrevision radiographic measurements included lateral talo-first metatarsal angle (Meary's angle), talonavicular coverage angle, calcaneal pitch, and hindfoot moment arm (HMA). Meary's angle >4 degrees was considered a planus deformity and HMA >9.1 mm was considered a hindfoot valgus deformity; patients fulfilling both criteria were categorized as having planovalgus deformity. Measurements in the contralateral foot were performed to determine whether alignment of the involved side was attributed to failed treatment or a preexisting deformity. Visual analog scale and Foot and Ankle Outcome Scores were compared and average follow-up was 20.1 months (range, 14-26).

RESULTS

Preoperatively, 20 of 21 (95%) patients had a form of valgus heel alignment (planovalgus, n = 11; hindfoot valgus only, n = 9), and 1 had an isolated planus deformity. The contralateral side revealed similar deformity, with 17 of 21 (81%) patients having a form of valgus heel alignment (planovalgus, n = 13; hindfoot valgus only, n = 4) and 4 patients with an isolated planus deformity. All patients underwent realignment surgery with medial displacement calcaneal osteotomy. All radiographic parameters except Meary's angle (P = .885) significantly improved postoperatively along with significantly improved clinical outcomes.

CONCLUSION

Recurrent pain following the Kidner procedure was associated with valgus heel alignment. Revision surgery including realignment procedure alleviated pain and improved functional outcomes with minimal complications. Therefore, we recommend assessing heel alignment in patients presenting with recurrent pain following the Kidner procedure.

LEVEL OF EVIDENCE

Level IV, case series.

Strength of Interference Screw Fixation to Cuboid vs Pulvertaft Weave to Peroneus Brevis for Tibialis Posterior Tendon Transfer for Foot Drop

BACKGROUND

Tibialis posterior (TP) tendon transfer is an effective treatment for foot drop. Currently, standard practice is to immobilize the ankle in a cast for 6 weeks nonweightbearing, risking postoperative stiffness. To assess whether early active dorsiflexion and protected weightbearing could be safe, the current study assessed tendon displacement under cyclic loading and load to failure, comparing the Pulvertaft weave (PW) to interference screw fixation (ISF) in a cadaveric foot model.

METHODS

Twenty-four cadaveric ankles had TP tendon transfer performed, 12 with the PW technique and 12 with ISF to the cuboid. The TP tendon was cycled 1000 times at 50 to 150 N and then loaded to failure in a materials testing machine. Tendon displacement at the insertion site was recorded every 100 cycles. An independent t test and 2-way analysis of variance were performed to compare techniques, with a significance level of P < .05.

RESULTS

Mean tendon displacement was similar in the PW group (2.9 ± 2.5 mm [mean ± SD]) compared with the ISF group (2.4 ± 1.1 mm), P = .35. One specimen in the ISF group failed early by tendon pullout. None of the PW group failed early, although displacement of 8.9 mm was observed in 1 specimen. Mean load to failure was 419.1 ± 82.6 N in the PW group in comparison to 499.4 ± 109.6 N in the ISF group, P = .06.

CONCLUSION

For TP tendon transfer, ISF and PW techniques were comparable, with no differences in tendon displacement after cyclical loading or load to failure. Greater variability was observed in the PW group, suggesting it may be a less reliable technique.

CLINICAL RELEVANCE

The results indicate that early active dorsiflexion and protected weightbearing may be safe for clinical evaluation, with potential benefits for the patient compared with cast immobilization.

Revision Surgery for Recurrent Pain after Excision of the Accessory Navicular and Relocation of the Tibialis Posterior Tendon

BACKGROUND

The results of operative treatments for symptomatic accessory navicular are debatable. In some cases, recurrent pain may develop after the Kidner procedure. The purpose of this study is to review the reasons for recurrent pain after the Kidner procedure and to suggest possible options for revision surgery.

METHODS

We reviewed the clinical and radiological outcomes in 9 patients who underwent revision surgery for recurrent pain after the Kidner procedure. During the revision surgery, the tibialis posterior tendon was reattached to the navicular either by advancing the tendon in 4 patients or by lengthening the tendon in another 4 patients. In the other 1 patient, the flexor digitorum longus tendon was transferred. Surgeries for the accompanying deformities were performed simultaneously in all patients. The results were evaluated using the American Orthopaedic Foot and Ankle Society ankle-hindfoot score and a visual analog scale. The mean follow-up was 2.3 years (range, 1 to 5 years).

RESULTS

The mean American Orthopedic Foot and Ankle Society ankle-hindfoot score improved from 71.25 to 81.50 in the advancement group, and 71.75 to 90.00 in the lengthening group. The mean visual analog scale improved from 7.75 to 4.25 in the advancement group and from 7.50 to 1.75 in the lengthening group.

CONCLUSIONS

Recurrent pain after the Kidner procedure was associated with pes planovalgus or hindfoot valgus deformity. In revision surgery, correction of the associated deformities and reattachment of the tibialis posterior tendon after lengthening may need to be considered.

The effects of short foot exercises and arch support insoles on improvement in the medial longitudinal arch and dynamic balance of flexible flatfoot patients

[Purpose] The purpose of the present study is to apply short foot exercises and arch support insoles in order to improve the medial longitudinal arch of flatfoot and compare the results to identify the effects of the foregoing exercises on the dynamic balance of the feet and the lower limbs. [Subjects and Methods] Fourteen university students with flexible flatfoot were selected by conducting navicular drop tests and randomly assigned to a short foot exercise group of seven subjects and an arch support insoles group of seven subjects. The intervention in the experiment was implemented for 30 minutes per time, three times per week for five weeks in total. [Results] In inter-group comparison conducted through navicular drop tests and Y-balance tests, the short foot exercise group showed significant differences. Among intra-group comparisons, in navicular drop tests, the short foot exercise group showed significant decreases. In Y-balance tests, both the short foot exercise group and the arch support insoles group showed significant increases. [Conclusion] In the present study, it could be seen that to improve flatfoot, applying short foot exercises was more effective than applying arch support insoles in terms of medial longitudinal arch improvement and dynamic balance ability.

The effects of hip external rotator exercises and toe-spread exercises on lower extremity muscle activities during stair-walking in subjects with pronated foot

[Purpose] The purpose of the present study was to examine the effects of toe-spread (TS) exercises and hip external rotator strengthening exercises for pronated feet on lower extremity muscle activities during stair-walking. [Subjects and Methods] The participants were 20 healthy adults with no present or previous pain, no past history of surgery on the foot or the ankle, and no foot deformities. Ten subjects performed hip external rotator strengthening exercises and TS exercises and the remaining ten subjects performed only TS exercises five times per week for four weeks. [Results] Less change in navicular drop height occurred in the group that performed hip external rotator exercises than in the group that performed only TS exercises. The group that performed only TS exercises showed increased abductor hallucis muscle activity during both stair-climbing and -descending, and the group that performed hip external rotator exercises showed increased muscle activities of the vastus medialis and abductor hallucis during stair-climbing and increased muscle activity of only the abductor hallucis during stair-descending after exercise. [Conclusion] Stair-walking can be more effectively performed if the hip external rotator muscle is strengthened when TS exercises are performed for the pronated foot.

Comparison of dynamic balance ability in healthy university students according to foot shape

[Purpose] This study aimed to compare dynamic balance ability according to foot shape, defined as normal, pronated, or supinated on the basis of the height of the medial arch. [Subjects] In this study, 14 subjects for the pronated foot group, 14 for the supinated foot group, and 14 for the normal foot group were selected from among 162 healthy university students by using the navicular drop test proposed by Brody. To measure dynamic balance ability, a star excursion balance test (SEBT) was conducted for each group, in which a cross-shaped line and lines at 45° in eight directions were drawn on the floor. In this study, only three directions were used, namely anterior, posterolateral, and posteromedial. The mean of the SEBT was calculated by measuring three times for each group, and the values were standardized using the following equation: measured value/leg length × 100. [Results] No significant differences in dynamic balance ability were found between the normal, pronated, and supinated foot groups. [Conclusion] No significant differences in dynamic balance ability according to the foot shape were found among the healthy university students with normal, pronated, and supinated feet.

An Ankle-Foot Orthosis With a Lateral Extension Reduces Forefoot Abduction in Subjects With Stage II Posterior Tibial Tendon Dysfunction

STUDY DESIGN

Controlled laboratory, repeated measures.

BACKGROUND

Posterior tibial tendon dysfunction is a common musculoskeletal problem that includes tendon degeneration and collapse of the medial arch of the foot (flatfoot deformity). Ankle-foot orthoses (AFOs) typically are used to correct flatfoot deformity. Correction of flatfoot deformity involves increasing forefoot adduction, forefoot plantar flexion, and hindfoot inversion.

OBJECTIVES

To test whether a foot orthosis with a lateral extension reduces forefoot abduction in patients with stage II posterior tibial tendon dysfunction while walking.

METHODS

The gait of 15 participants with stage II posterior tibial tendon dysfunction was evaluated under 3 conditions: a standard AFO, an AFO with a lateral extension, and a shoe-only control condition. Kinematic variables of interest were evaluated at designated time points in the gait cycle and included hindfoot inversion/eversion, forefoot plantar flexion/dorsiflexion, and forefoot abduction/adduction. A 3-by-4, repeated-measures analysis of variance (brace condition by gait phase) was used to compare variables across conditions.

RESULTS

The AFO with a lateral extension resulted in a significantly greater change in forefoot adduction compared to the standard AFO (2.6°, P = .02) and shoe-only conditions (4.1°, P<.01) across all phases of stance. Forefoot plantar flexion was significantly increased when comparing the standard AFO and AFO with a lateral extension to the shoe-only condition. The AFO with the lateral extension also demonstrated significantly increased hindfoot inversion during the loading response and terminal stance phases.

CONCLUSION

Off-the-shelf and standard AFOs have been shown to improve forefoot plantar flexion and hindfoot eversion, but not forefoot adduction. A lateral extension added to a standard AFO along the forefoot significantly improved forefoot adduction in participants with posterior tibial tendon dysfunction while walking.

Randomized Controlled Trial Comparing Orthosis Augmented by Either Stretching or Stretching and Strengthening for Stage II Tibialis Posterior Tendon Dysfunction

BACKGROUND

The value of strengthening and stretching exercises combined with orthosis treatment in a home-based program has not been evaluated. The purpose of this study was to compare the effects of augmenting orthosis treatment with either stretching or a combination of stretching and strengthening in participants with stage II tibialis posterior tendon dysfunction (TPTD).

METHODS

Participants included 39 patients with stage II TPTD who were recruited from a medical center and then randomly assigned to a strengthening or stretching treatment group. Excluding 3 dropouts, there were 19 participants in the strengthening group and 17 in the stretching group. The stretching treatment consisted of a prefabricated orthosis used in conjunction with stretching exercises. The strengthening treatment consisted of a prefabricated orthosis used in conjunction with the stretching and strengthening exercises. The main outcome measures were self-report (ie, Foot Function Index and Short Musculoskeletal Function Assessment) and isometric deep posterior compartment strength. Two-way analysis of variance was used to test for differences between groups at 6 and 12 weeks after starting the exercise programs.

RESULTS

Both groups significantly improved in pain and function over the 12-week trial period. The self-report measures showed minimal differences between the treatment groups. There were no differences in isometric deep posterior compartment strength.

CONCLUSIONS

A moderate-intensity, home-based exercise program was minimally effective in augmenting orthosis wear alone in participants with stage II TPTD.

LEVEL OF EVIDENCE

Level I, prospective randomized study.

Preinjury and postinjury running analysis along with measurements of strength and tendon length in a patient with a surgically repaired Achilles tendon rupture

STUDY DESIGN

Case report.

BACKGROUND

The Achilles tendon is the most frequently ruptured tendon, and the incidence of Achilles tendon rupture has increased in the last decade. The rupture generally occurs without any preceding warning signs, and therefore preinjury data are seldom available. This case represents a unique opportunity to compare preinjury running mechanics with postinjury evaluation in a patient with an Achilles tendon rupture.

CASE DESCRIPTION

A 23-year-old female sustained a right complete Achilles tendon rupture while playing soccer. Running mechanics data were collected preinjury, as she was a healthy participant in a study on running analysis. In addition, patient-reported symptoms, physical activity level, strength, ankle range of motion, heel-rise ability, Achilles tendon length, and running kinetics were evaluated 1 year after surgical repair.

OUTCOMES

During running, greater ankle dorsiflexion and eversion and rearfoot abduction were noted on the involved side postinjury when compared to preinjury data. In addition, postinjury, the magnitude of all kinetics data was lower on the involved limb when compared to the uninvolved limb. The involved side displayed differences in strength, ankle range of motion, heel rise, and tendon length when compared to the uninvolved side 1 year after injury.

DISCUSSION

Despite a return to normal running routine and reports of only minor limitations with running, considerable changes were noted in running biomechanics 1 year after injury. Calf muscle weakness and Achilles tendon elongation were also found when comparing the involved and uninvolved sides.

Effect of ankle-foot orthotic devices on foot kinematics in Stage II posterior tibial tendon dysfunction

BACKGROUND

Data are limited on the various orthotic devices available for patients with Stage II posterior tibial tendon dysfunction (PTTD). Foot kinematics observed while walking with an orthotic device are hypothesized to be associated with clinical outcomes and could be used to refine future device designs.

METHODS

Fifteen subjects (age, 63.6 ± 6.8 years) with Stage II PTTD walked in the lab under four conditions: (1) shoe only (control condition), (2) shoe with a custom solid AFO (Arizona Co, Mesa, AZ), (3) shoe with a custom articulated AFO (Arizona Co, Mesa, AZ), and (4) shoe with an off-the-shelf AFO (AirLift, DJ Orthopedics). Kinematic data were collected to determine the degree of hindfoot inversion, forefoot plantarflexion (reflective of raising the MLA), and forefoot adduction associated with each condition.

RESULTS

The custom articulated device was associated with greater hindfoot inversion compared to the shoe only condition at loading response (p = 0.002), mid-stance (p < 0.001), and terminal stance (p = 0.02). The custom articulated device, custom solid device, and off-the-shelf device were associated with greater forefoot plantarflexion compared to the shoe only condition across all four phases of stance. There were no differences between any of the devices and the shoe condition associated with forefoot adduction.

CONCLUSION

The custom devices were associated with greater hindfoot inversion and forefoot plantarflexion compared to walking with only a shoe, while the off-the-shelf device was associated with forefoot plantarflexion but no change in hindfoot motion. None of the devices corrected forefoot abduction compared to the shoe only condition.

CLINICAL RELEVANCE

The current biomechanical data may aid in understanding the clinical outcomes seen using these devices as well as provide data to support new designs.

The effects of surface slope on multi-segment foot kinematics in healthy adults

Previous work evaluating the effects of surface slope on gait has focused on lower extremity kinematics and kinetics. However, an assessment of multi-segment foot kinematics during walking on inclined and declined ramps has not been previously reported. Sagittal ankle motion using a single rigid body foot model and three-dimensional hindfoot and forefoot kinematics for 24 healthy adults (16 females and 8 males, average age 25.5 ± 4.4 years) were compared during level surface, inclined surfaces of 3%, 6%, 9% and 12% grade and a declined surface of approximately 7.5% grade at a constant speed using a standard treadmill. Significant differences in peak hindfoot plantarflexion, sagittal plane range of motion and time of peak dorsiflexion, plantarflexion, varus and valgus were seen between surface slope conditions. Significant changes were also seen in forefoot plantarflexion and sagittal plane range of motion however the maximum difference between conditions was less than 3°. These results indicate that foot mechanics can be significantly altered when ambulating on ramps in healthy adults. Specifically, treadmill protocols which incorporate different surface slopes often encountered during ambulation of daily living, may provide an improved technique in evaluating a patient's ability to function in the community.

Deep posterior compartment strength and foot kinematics in subjects with stage II posterior tibial tendon dysfunction

BACKGROUND

Tibialis posterior muscle weakness has been documented in subjects with Stage II posterior tibial tendon dysfunction (PTTD) but the effect of weakness on foot structure remains unclear. The association between strength and flatfoot kinematics may guide treatment such as the use of strengthening programs targeting the tibialis posterior muscle.

MATERIALS AND METHODS

Thirty Stage II PTTD subjects (age; 58.1 +/- 10.5 years, BMI 30.6 +/- 5.4) and 15 matched controls (age; 56.5 +/- 7.7 years, BMI 30.6 +/- 3.6) volunteered for this study. Deep Posterior Compartment strength was measured from both legs of each subject and the strength ratio was used to compare each subject's involved side to their uninvolved side. A 20% deficit was defined, a priori, to define two groups of subjects with PTTD. The strength ratio for each group averaged; 1.06 +/- 0.1 (range 0.87 to 1.36) for controls, 1.06 +/- 0.1 (range, 0.89 to 1.25), for the PTTD strong group, and 0.64 +/- 0.2 (range 0.42 to 0.76) for the PTTD weak group. Across four phases of stance, kinematic measures of flatfoot were compared between the three groups using a two-way mixed effect ANOVA model repeated for each kinematic variable.

RESULTS

Subjects with PTTD regardless of group demonstrated significantly greater hindfoot eversion compared to controls. Subjects with PTTD who were weak demonstrated greater hindfoot eversion compared to subjects with PTTD who were strong. For forefoot abduction and MLA angles the differences between groups depended on the phase of stance with significant differences between each group observed at the pre-swing phase of stance.

CONCLUSION

Strength was associated with the degree of flatfoot deformity observed during walking, however, flatfoot deformity may also occur without strength deficits.

CLINICAL RELEVANCE

Strengthening programs may only partially correct flatfoot kinematics while other clinical interventions such as bracing or surgery may also be indicated.

Isolated talonavicular arthrodesis in patients with rheumatoid arthritis of the foot and tibialis posterior tendon dysfunction

BACKGROUND

The foot is often affected in patients with rheumatoid arthritis. Subtalar joints are involved more frequently than ankle joints. Deformities of subtalar joints often lead to painful flatfoot and valgus deformity of the heel. Major contributors to the early development of foot deformities include talonavicular joint destruction and tibialis posterior tendon dysfunction, mainly due to its rupture.

METHODS

Between 2002 and 2005 we performed isolated talonavicular arthrodesis in 26 patients; twenty women and six men. Tibialis posterior tendon dysfunction was diagnosed preoperatively by physical examination and by MRI. Talonavicular fusion was achieved via screws in eight patients, memory staples in twelve patients and a combination of screws and memory staples in six cases. The average duration of immobilization after the surgery was four weeks, followed by rehabilitation. Full weight bearing was allowed two to three months after surgery.

RESULTS

The mean age of the group at the time of the surgery was 43.6 years. MRI examination revealed a torn tendon in nine cases with no significant destruction of the talonavicular joint seen on X-rays. Mean of postoperative followup was 4.5 years (3 to 7 years). The mean of AOFAS Hindfoot score improved from 48.2 preoperatively to 88.6 points at the last postoperative followup. Eighteen patients had excellent results (none, mild occasional pain), six patients had moderate pain of the foot and two patients had severe pain in evaluation with the score. Complications included superficial wound infections in two patients and a nonunion developed in one case.

CONCLUSIONS

Early isolated talonavicular arthrodesis provides excellent pain relief and prevents further progression of the foot deformities in patients with rheumatoid arthritis and tibialis posterior tendon dysfunction.

A comparison of multi-segment foot kinematics during level overground and treadmill walking

Previous work comparing treadmill and overground walking has focused on lower extremity motion and kinetics, with few identified differences. However, a comparison of multi-segment foot kinematics between these conditions has not been previously reported. Sagittal ankle motion using a single rigid body foot model and three-dimensional hindfoot and forefoot kinematics were compared during barefoot, level, overground walking at a self-selected speed and treadmill walking at a similar speed for 20 healthy adults. Slight differences were seen in ankle plantarflexion and hindfoot plantarflexion during first rocker, as well as peak forefoot eversion and abduction, however all changes were less than 3 degrees , and most were within the day-to-day repeatability. These results indicate that foot mechanics as determined using a multi-segment foot model were similar between overground and treadmill walking at similar speeds in healthy adults. Treadmill protocols may provide a controlled method to analyze a patient's ability to adapt to walking at different speeds and surface slopes, which are encountered often during ambulation of daily living.

Choosing among 3 ankle-foot orthoses for a patient with stage II posterior tibial tendon dysfunction

STUDY DESIGN

Case report.

BACKGROUND

No head-to-head comparisons of different orthoses for patients with stage II posterior tibial tendon dysfunction (PTTD) have been performed to date. Additionally, the cost of orthoses varies considerably, thus choosing an effective orthosis that is affordable to the patient is largely a trial-and-error process.

CASE DESCRIPTION

A 77-year-old woman was seen with complaints of abnormal foot posture ('my foot is out'), minimal medial foot and ankle pain, and a 3-year history of conservatively managed stage II PTTD. The patient was not able to complete 1 single-limb heel rise on the involved side, while she could complete 3 on the uninvolved side. Ankle strength testing revealed a mild to moderate loss of plantar flexor strength (20%-31% deficit on the involved side), combined with a 22% deficit in isometric ankle inversion and forefoot adduction strength. To assist this patient in managing her flatfoot posture and PTTD, 3 orthoses were considered: an off-the-shelf ankle-foot orthosis (AFO), a custom solid AFO, and a custom articulated AFO. The patient's chief complaint was partly cosmetic (ìmy foot is outî). As decreasing flatfoot kinematics may unload the tibialis posterior muscle, thus prevent the progression of foot deformity, the primary goal of orthotic intervention was to improve flatfoot kinematics. Given the difficulties in clinical approaches to evaluating flatfoot kinematics, a quantitative gait analysis, using a multisegment foot model, was used.

OUTCOMES

In the frontal plane, all 3 orthoses were associated with small changes toward hindfoot inversion. In the sagittal plane, between 2.7 degrees and 6.1 degrees , greater forefoot plantar flexion (raising the medial longitudinal arch) occurred. There were no differences among the orthoses on hindfoot inversion and forefoot plantar flexion. In the transverse plane, the off-the-shelf design was associated with forefoot abduction, the custom solid orthosis was associated with no change, and the custom articulated orthosis was associated with forefoot adduction.

DISCUSSION

Based on gait analysis, the higher-cost custom articulated orthosis was chosen as optimal for the patient. This custom articulated orthosis was associated with the greatest change in flatfoot deformity, assessed using gait analysis. The patient felt it produced the greatest correction in foot deformity. Reducing flatfoot deformity while allowing ankle movement may limit progression of stage II PTTD.

LEVEL OF EVIDENCE

Therapy, level 4.

Foot kinematics during a bilateral heel rise test in participants with stage II posterior tibial tendon dysfunction

STUDY DESIGN

Experimental laboratory study using a cross-sectional design.

OBJECTIVES

To compare foot kinematics, using 3-dimensional tracking methods, during a bilateral heel rise between participants with posterior tibial tendon dysfunction (PTTD) and participants with a normal medial longitudinal arch (MLA).

BACKGROUND

The bilateral heel rise test is commonly used to assess patients with PTTD; however, information about foot kinematics during the test is lacking.

METHODS

Forty-five individuals volunteered to participate, including 30 patients diagnosed with unilateral stage II PTTD (mean +/- SD age, 59.8 +/- 11.1 years; body mass index, 29.9 +/- 4.8 kg/m2) and 15 controls (mean +/- SD age, 56.5 +/- 7.7 years; body mass index, 30.6 +/- 3.6 kg/m2). Foot kinematic data were collected during a bilateral heel rise task from the calcaneus (hindfoot), first metatarsal, and hallux, using an Optotrak motion analysis system and Motion Monitor software. A 2-way mixed-effects analysis of variance model, with normalized heel height as a covariate, was used to test for significant differences between the normal MLA and PTTD groups.

RESULTS

The patients in the PTTD group exhibited significantly greater ankle plantar flexion (mean difference between groups, 7.3 degrees ; 95% confidence interval [CI]: 5.1 degrees to 9.5 degrees ), greater first metatarsal dorsiflexion (mean difference between groups, 9.0 degrees ; 95% CI: 3.7 degrees to 14.4 degrees ), and less hallux dorsiflexion (mean difference, 6.7 degrees ; 95% CI: 1.7 degrees to 11.8 degrees ) compared to controls. At peak heel rise, hindfoot inversion was similar (P = .130) between the PTTD and control groups.

CONCLUSION

Except for hindfoot eversion/inversion, the differences in foot kinematics in participants with stage II PTTD, when compared to the control group, mainly occur as an offset, not an alteration in shape, of the kinematic patterns.

Ankle and foot kinematics associated with stage II PTTD during stance

BACKGROUND

Subjects with stage II posterior tibial tendon dysfunction (PTTD) exhibit abnormal foot kinematics; however, how individual segment kinematics (hindfoot (HF) or first metatarsal (first MET) segments) influence global foot kinematics is unclear. The purpose of this study was to compare foot and ankle kinematics and sagittal plane HF and first MET segment kinematics between stage II PTTD and controls.

MATERIALS AND METHODS

Thirty patients with stage II PTTD and 15 healthy controls were evaluated. Kinematic data from the tibia, calcaneus, and first MET were collected during walking using three dimensional motion analysis techniques. A three-segment foot model (HF, calcaneus; first MET, first metatarsal, and tibia) was used to calculate relative angles (ankle, HF relative to tibia; midfoot, first MET relative to HF) and segment angles (HF and first MET relative to the global). A mixed effect ANOVA model was utilized to compare angles between groups for each variable.

RESULTS

Patients with PTTD showed greater ankle plantarflexion (p = 0.02) by 6.8 degrees to 8.4 degrees prior to or at 74% of stance; greater HF eversion (p < 0.01) across stance (mean difference = 4.5 degrees); and greater first MET dorsiflexion (p < 0.01) across stance (mean difference = 8.8 degrees). HF and first MET segment angles revealed greater HF dorsiflexion (p = 0.01) during early stance and greater first MET dorsiflexion (p = 0.001) across stance.

CONCLUSION

Abnormal HF and first MET segment kinematics separately influence both ankle and midfoot movement during walking in subjects with stage II PTTD.

CLINICAL RELEVANCE

These abnormal kinematics may serve as another measure of response to clinical treatment and/or guide for clinical strategies (exercise, orthotics, and surgery) seeking to improve foot kinematics.

Effects of the AirLift PTTD brace on foot kinematics in subjects with stage II posterior tibial tendon dysfunction

STUDY DESIGN

Experimental laboratory study.

OBJECTIVES

To investigate the effect of inflation of the air bladder component of the AirLift PTTD brace on relative foot kinematics in subjects with stage II posterior tibial tendon dysfunction (PTTD).

BACKGROUND

Orthotic devices are commonly recommended in the conservative management of stage II PTTD to improve foot kinematics.

METHODS AND MEASURES

Ten female subjects with stage II PTTD walked in the laboratory wearing the AirLift PTTD brace during 3 testing conditions (air bladder inflation to 0, 4, and 7 PSI [SI equivalent: 0, 27,579, and 48,263 Pa]). Kinematics were recorded from the tibia, calcaneus (hindfoot), and first metatarsal (forefoot), using an Optotrak motion analysis system. Comparisons were made between air bladder inflation and the 0-PSI condition for each of the dependent kinematic variables (hindfoot eversion, forefoot abduction, and forefoot dorsiflexion).

RESULTS

Greater hindfoot inversion was observed with air bladder inflation during the second rocker (mean, 1.7 degrees; range, -0.7 degrees to 6.1 degrees). Less consistent changes in forefoot plantar flexion and forefoot adduction occurred with air bladder inflation. The greatest change toward forefoot plantar flexion was observed during the third rocker (mean, 1.4 degrees; range, -3.8 degrees to 3.9 degrees). The greatest change towards adduction was observed during the third rocker (mean, 2.3 degrees; range, -3.4 degrees to 6.5 degrees).

CONCLUSIONS

On average, the air bladder component of the AirLift PTTD brace was successful in reducing the amount of hindfoot eversion observed in subjects with stage II PTTD; however, the effect on forefoot motion was more variable. Some subjects tested had marked improvement in foot kinematics, while 2 subjects demonstrated negative results. Specific foot characteristics are hypothesized to explain these varied results.

The effect of Stage II posterior tibial tendon dysfunction on deep compartment muscle strength: a new strength test

BACKGROUND

The purpose of this study was to compare isometric subtalar inversion and forefoot adduction strength in subjects with Stage II posterior tibial tendon dysfunction (PTTD) to controls.

MATERIALS AND METHODS

Twenty four subjects with Stage II PTTD and fifteen matched controls volunteered for this study. A force transducer (Model SML-200, Interface, Scottsdale, AZ) was connected with a resistance plate and oscilloscope (TDS 410A, Tektronix, Beaverton, OR) to the foot. Via the oscilloscope, subjects were given feedback on the amount of force produced and muscle activation of the anterior tibialis (AT) muscle. Subjects were instructed to maintain a plantar flexion force while performing a maximal voluntary subtalar inversion and forefoot adduction effort. A two-way ANOVA model with the factors including, side (involved/uninvolved) and group (control/PTTD) was used.

RESULTS

The PTTD group on the involved side showed significantly decreased subtalar inversion and foot adduction strength (0.70 +/- 0.24 N/Kg) compared to the uninvolved side (0.94 +/- 0.24 N/Kg) and controls (involved side = 0.99 +/- 0.24 N/Kg, uninvolved side = 0.97 +/- 0.21 N/Kg). The average AT activation was between 11% to 17% for both groups, however, considerable variability in subjects with PTTD.

CONCLUSION

These data confirm a subtalar inversion and forefoot adduction strength deficit by 20% to 30% in subjects with Stage II PTTD. Although isolating the PT muscle is difficult, a test specific to subtalar inversion and forefoot adduction demonstrated the weakness in this population.

Comparison of changes in posterior tibialis muscle length between subjects with posterior tibial tendon dysfunction and healthy controls during walking

STUDY DESIGN

Case control study.

OBJECTIVE

To compare posterior tibialis (PT) length between subjects with stage II posterior tibial tendon dysfunction (PTTD) and healthy controls during the stance phase of gait.

BACKGROUND

The abnormal kinematics demonstrated by subjects with stage II PTTD are presumed to be associated with a lengthened PT musculotendon, but this relationship has not been fully explored.

METHODS

Seventeen subjects with stage II PTTD and 10 healthy controls volunteered for this study. Subject-specific foot kinematics were collected using 3-D motion analysis techniques for input into a general model of PT musculotendon length (PTLength). The kinematic inputs included hindfoot eversion/inversion (HF Ev/lnv), forefoot abduction/adduction (FF Ab/Add), forefoot plantar flexion/dorsiflexion (FF Pf/Df), and ankle plantar flexion/dorsiflexion (Ankle Pf/Df). To estimate the change in PTLength from neutral the following model was used: PTLength = 0.401(HF Ev/lnv) + 0,270(FF Ab/Add) + 0.137(FF Pf/Df) + 0.057(Ankle Pf/Df). Positive values indicated lengthening from the subtalar neutral (STN) position, while negative values indicated shortening relative to the STN position. A 2-way analysis of variance (ANOVA) model was used to compare PTLength between groups across the stance phases of walking (loading response, midstance, terminal stance, and preswing). Also, a 2-way ANOVA was used to assess the foot kinematics that contributed to alterations in PTLength. The Short Musculoskeletal Functional Assessment Index and Mobility subscale were used to compare function and mobility.

RESULTS

PTLength was significantly greater (lengthened) relative to the STN position in the PTTD group compared to the control group across all phases of stance, with the greatest between-group difference in PTLength occurring during preswing. The greater PTLength in subjects with PTTD compared to controls was principally attributed to significantly greater HF Ev/lnv during loading response (P = .014) and midstance (P = .015). During terminal stance and preswing, each kinematic input to estimate PTLength contributed to lengthening (main effect, P = .03 and P = .01, respectively). Subjects with PTTD with abnormally greater PTLength reported significantly lower function (P = .04) and mobility (P = .03) compared to subjects with PTTD with normal PTLength during walking.

CONCLUSIONS

The greater PTLength, as determined from foot kinematics, suggests that the PT musculotendon is lengthened in subjects with stage II PTTD, compared to healthy controls. The amount of lengthening is not dependent on the phase of gait; however, different foot kinematics contribute to PTLength across the stance phase. Targeting these foot kinematics may limit lengthening of the PT musculotendon. Subjects with excessive PT lengthening experience a decrease in function.