Ivan Birch

The impact of hallux valgus on foot kinematics: A cross-sectional, comparative study

BACKGROUND Hallux valgus is a very common foot deformity in modern societies. The impact of this condition on foot function has been described qualitatively and quantitatively. Published patho-mechanical models are mainly underpinned by findings originating from plantar pressure measurements. However, the kinematical patterns of the many foot segments during gait have not been quantified. This study aims to evaluate the kinematics of the various foot segments in the presence of this deformity. METHODS Using the Oxford Foot Model and a 12-camera Motion Analysis System, gait analysis was conducted on a convenience sample of 20 participants with hallux valgus and compared to that of 22 randomly selected symptom-free volunteers. Differences between temporal and kinematical data between groups were analyzed using the unpaired parametric Student t-test (significance level p<0.01). RESULTS During specific gait events, a different range of motion was found at several inter-segment angles. Particularly, the range of motion of the hallux (sagittal plane) and hindfoot (frontal-transverse planes) during stance were significantly different (p<0.01). CONCLUSION Sagittal plane kinematics of the hallux is affected by the first ray deformity in this condition. However, the impact on other segments was found to be limited. This suggests that the patho-mechanical consequences remain limited to the weight bearing function of the first ray.

Inter- and intra-observer reliability of masking in plantar pressure measurement analysis

Plantar pressure measurement is an important tool in gait analysis. Manual placement of small masks (masking) is increasingly used to calculate plantar pressure characteristics. Little is known concerning the reliability of manual masking. The aim of this study was to determine the reliability of masking on 2D plantar pressure footprints, in a population with forefoot deformity (i.e. hallux valgus). Using a random repeated-measure design, four observers identified the third metatarsal head on a peak-pressure barefoot footprint, using a small mask. Subsequently, the location of all five metatarsal heads was identified, using the same size of masks and the same protocol. The 2D positional variation of the masks and the peak pressure (PP) and pressure time integral (PTI) values of each mask were calculated. For single-masking the lowest inter-observer reliability was found for the distal-proximal direction, causing a clear, adverse impact on the reliability of the pressure characteristics (PP and PTI). In the medial-lateral direction the inter-observer reliability could be scored as high. Intra-observer reliability was better and could be scored as high or good for both directions, with a correlated improved reliability of the pressure characteristics. Reliability of multi-masking showed a similar pattern, but overall values tended to be lower. Therefore, small sized masking in order to define pressure characteristics in the forefoot should be done with care.

Reliability of the Maestro radiographic measuring tool

Introduction: Maestro et al. presented a detailed preoperative measuring and classification technique for the forefoot. The purpose of this paper was to determine if the PACS system will allow the Maestro measuring technique and classification system to be reliable and precise. Materials and Methods: This radiographic study was conducted on 73 subjects (36 females, 37 males, age 30.4 ± 9.9) who had given informed consent. The geometrical progression was measured for each foot of each subject by the two observers according to the measuring methodology of Maestro. The intraclass correlation coefficient (ICC), and the 95% lower confidence limit (95% LCL) were calculated for the geometrical progression variables of the lesser metatarsals. Once the feet were classified by each observer, the accordance in classification of the feet was analyzed between the two observers. Results: The radiographic measuring technique of Maestro was a reliable method for analyzing the mathematical progression of the lesser metatarsals through the use of the PACS system. A 92.6% concordance in the classification of the radiological forefoot morphotypes was found between the two observers. Conclusion: We found Maestro et al.s measuring technique and classification system precise and reproducible using PACS digital radiographs. It is hoped that utilization of this technique will lead to better forefoot outcomes and patient satisfaction. Level of Evidence: IV, Case Series

A comparison of the Doppler ultrasound interpretation by student and registered podiatrists

BackgroundHand held Doppler ultrasound machines are routinely used by podiatrists to assess the arterial perfusion of the lower limb. They are practical, painless and effective as a screening tool, and the available general evidence would suggest that interpretation by practitioners is reliable. This study compared the abilities of student and Health and Care Professions Council (HCPC) registered podiatrists to identify correctly Doppler ultrasound outputs.MethodA prospective single blind comparative study design was utilised. Fifteen Doppler recordings of the blood flow in the posterior tibial artery, five each of monophasic, biphasic and triphasic blood flow, were used to compare the interpretation abilities of 30 undergraduate podiatry students and 30 HCPC registered podiatrists. Chi-squared analysis of the results was undertaken.ResultsChi-squared analysis found that there was no statistically significant difference between the overall abilities of student podiatrists and HCPC registered podiatrists to identify correctly Doppler ultrasound recordings (p = 0.285). No significant difference was found in their ability to identify Doppler ultrasound recordings of monophasic, biphasic or triphasic blood flow (p > 0.050).ConclusionThe results of this relatively small study suggest that both student and HCPC registered podiatrists are in general able to identify the nature of blood flow based on the output of handheld Doppler ultrasound units. However, the results raise an issue regarding professional development of practitioners who might have been expected to have enhanced their skills of Doppler ultrasound sound identification since professional registration.

The in vitro reliability of the CODA MPX30 as the basis for a method of assessing the in vivo motion of the subtalar joint.

BACKGROUND The considerable variation in subtalar joint structure and function shown by studies indicates the importance of developing a noninvasive in vivo technique for assessing subtalar joint movement. This article reports the in vitro testing of the CODA MPX30, an active infrared marker motion analysis system. This work represents the first stage in the development of a noninvasive in vivo method for measuring subtalar joint motion during walking. METHODS The in vitro repeatability of the CODA MPX30 systems measurements of marker position, simple and intermarker set angles, was tested. Angular orientations of markers representing the position of the talus and the calcaneus were measured using a purpose-designed marker placement model. RESULTS Marker location measurements were shown to vary by less than 1.0 mm in all of the planes. The measurement of a 90° angle was also found to be repeatable in all of the planes, although measurements made in the yz plane were shown to be consistently inaccurate (mean, 92.47°). Estimation of segmental orientation was found to be repeatable. Estimations of marker set orientations were shown to increase in variability after a coordinate transform was performed (maximum SD, 1.14°). CONCLUSIONS The CODA MPX30 was shown to produce repeatable estimations of marker position. Levels of variation in segmental orientation estimates were shown to increase subsequent to coordinate transforms. The combination of the CODA MPX30 and an appropriate marker placement model offers the basis of an in vivo measurement strategy of subtalar joint movement, an important development in the understanding of the function of the joint during gait.

Quantification of skin marker movement at the malleoli and talar heads.

BACKGROUND Quantifying subtalar joint kinematics during locomotion is a major challenge but is critical to understanding foot function. The difficulty of modeling the subtalar joint is demonstrated by the plethora of three-dimensional multisegment foot models lacking specific consideration of the subtalar joint. Scientific attempts to develop an adequate method of quantifying subtalar joint kinematics should include investigation of the movement of skin-mounted markers. This study reports on a single-subject investigation into this topic. METHODS Radiopaque markers were attached to the skin overlying the medial and lateral malleoli and the medial and lateral talar heads of a single subject. Frontal, sagittal, and transverse plane radiographs were taken with the foot in the fully pronated and fully supinated positions. Parallax corrected measurements were taken of the displacement of the markers from the bony landmarks. Measurements were also taken of the effect of these displacements on angular calculations. RESULTS Skin movement at the four anatomical locations was not uniform, with displacements varying from 0.61 to 22.18 mm. Movement of the malleolar markers was found to be less than that of the talar head markers. The distortion of angular measurements caused by movement of the skin markers relative to the bony landmarks was found to be only 1° in the sagittal and transverse planes and 5° in the frontal plane. CONCLUSIONS For this subject, skin-mounted markers could be used to assess subtalar joint motion. Further studies are necessary to investigate the implications of these findings to the wider population.

Anatomical characteristics of the flexor digitorum accessorius longus muscle and their relevance to tarsal tunnel syndrome a systematic review.

BACKGROUND Clinical and cadaver studies have reported that supernumerary muscles could be the etiology of a variety of pathologic disorders, such as posterior impingement syndrome, tarsal tunnel syndrome (TTS), and flexor hallucis longus tenosynovitis. We describe a unique variant of the flexor digitorum accessorius longus (FDAL) muscle as an apparent cause of TTS, functioning as an independent flexor of the second toe, which has not been described in the literature. In addition to this case report, a systematic review was performed of TTS caused by the FDAL muscle. METHODS A targeted search of PubMed, the Cochrane Library, the Cumulative Index to Nursing and Allied Health Literature, and Web of Science identified full-text papers that fulfilled the inclusion and exclusion criteria. RESULTS Twenty-nine papers were identified for inclusion in the systematic review: 12 clinical papers of TTS caused by the FDAL muscle and 17 cadaver-based papers. CONCLUSIONS Clinicians often do not include the FDAL muscle in the differential diagnosis of TTS. This literature review suggests that the FDAL is an important muscle in terms of its functional and clinical significance. Knowledge of this muscle, its anatomical location and variations, and its magnetic resonance imaging characteristics may help clinicians make an accurate differential diagnosis.

A Novel Device for Standardizing Marker Placement at the Calcaneus

BACKGROUND The determination of anatomical reference frames in the rearfoot during three-dimensional multisegment foot modeling has been hindered by a variety of factors. One of these factors is related to the difficulty in palpating, or the absence of, anatomical landmarks. A novel device (the Calcaneal Marker Device) aimed at standardizing marker placement at the calcaneus was, therefore, developed and evaluated for its reliability. METHODS Throughout a random repeated-measures design, the repeatability of calcaneal marker placement was evaluated for two techniques: manual placement and placement using the Calcaneal Marker Device. Translational changes after marker placement and the clinical effect on intersegment angle calculation were quantified. RESULTS Intraobserver variability was greater in therapist 2 (<5.3 mm) compared with therapist 1 (<2.9 mm). Intraobserver variability was also found to be less than 1.6 mm throughout use of the device. Interobserver variability was found to be significantly higher for the position of markers placed manually (5.8 mm), whereas with the Calcaneal Marker Device, the variability remained lower (<1.3 mm). The effect on the computed intersegment angles followed a similar trend, with variability of 0.4° to 4.0° and 1.0° to 8.7° for CMD and manual placement, respectively. CONCLUSIONS These findings suggest that variations in marker placement are considerably reduced when the novel Calcaneal Marker Device is used, possibly toward the limits dictated by the fine motor skills of therapists and tissue artifacts.

Noninvasive quantification of subtalar joint kinematics: a pilot investigation.

A noninvasive method of assessing the motion of the subtalar joint was developed for use in clinical and research settings. Anatomical reference frames for the calcaneus and talus were produced using a marker placement model utilizing 14 markers. An asymptomatic individual was tested during barefoot walking with a CODA MPX30 system. Intertrial variability and motion patterns, in all three planes, of the calcaneus with respect to the talus were analyzed as part of a validation study. The observed patterns in all three planes were found to have good face validity with published literature as well as good consistency during stance. The findings of this study support the further use of this model in both clinical and research settings, allowing investigation of the motion patterns of a larger cohort than has hitherto been possible.

Arthroscopic Debridement After Total Ankle Arthroplasty

Background: Residual pain due to impingement after ankle arthroplasty can be addressed with arthroscopic debridement. Literature focusing on the effectiveness of arthroscopic debridement after total ankle arthroplasty (TAA) is scarce. The authors report a case series of 12 patients complaining of anterior or posterior impingement pain, 11 of which were in the absence of malalignment which were treated by arthroscopy. Methods: Of the 106 TAAs performed between 2003 and 2012, a total of 12 subjects reported postoperative pain resulting from anterior or anteromedial impingement, medial and/or lateral gutter impingement, posterior impingement, and/or ankylosis. All patients were reviewed on a regular basis through chart review, clinical examination, and radiologic evaluation. The average time to final follow-up was 58.8 months. The average period from the original TAA to the arthroscopic debridement was 38.2 months. Results: The median AOFAS hindfoot score was significantly (P < .05) improved from 64.6 preoperatively to 73.5 postoperatively. Eight subjects reported good pain relief after the arthroscopic debridement, and partial pain relief was reported by 4 subjects. Three patients with painful ankylosis had no improvement in the total range of motion of the TAA implant after the arthroscopic debridement. Conclusion: The results suggest that arthroscopic debridement in patients with residual pain due to impingement syndromes after TAA was effective in 8 of the 12 cases at 2 years’ follow-up. However, the results suggest that arthroscopic debridement in the presence of painful ankylosis associated with or without impingement syndromes results only in partial pain relief and does not improve the range of motion. Level of Evidence: Level IV, case series.