The subtalar joint axis palpation technique part 2: reliability and validity results using cadaver feet

Turmell-Meter: A Device for Estimating the Subtalar and Talocrural Axes of the Human Ankle Joint by Applying the Product of Exponentials Formula

The human ankle is a complex joint, most commonly represented as the talocrural and subtalar axes. It is troublesome to take in vivo measurements of the ankle joint. There are no instruments for patients lying on flat surfaces; employed in outdoor or remote sites. We have developed a "Turmell-meter" to address these issues. It started with the study of ankle anatomy and anthropometry. We also use the product of exponentials' formula to visualize the movements. We built a prototype using human proportions and statistics. For pose estimation, we used a trilateration method by applying tetrahedral geometry. We computed the axis direction by fitting circles in 3D, plotting the manifold and chart as an ankle joint model. We presented the results of simulations, a prototype comprising 45 parts, specifically designed draw-wire sensors, and electronics. Finally, we tested the device by capturing positions and fitting them into the bi-axial ankle model as a Riemannian manifold. The Turmell-meter is a hardware platform for human ankle joint axes estimation. The measurement accuracy and precision depend on the sensor quality; we address this issue by designing an electronics capture circuit, measuring the real measurement with a Vernier caliper. Then, we adjust the analog voltages and filter the 10-bit digital value. The Technology Readiness Level is 2. The proposed ankle joint model has the properties of a chart in a geometric manifold, and we provided the details.

Surgical Biomechanics: Principles of Procedure Choice

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

Slow velocity of the center of pressure and high heel pressures may increase the risk of Sever's disease: a case-control study

Background

This study determined if the body mass index, dynamic plantar-pressures, plantar surface contact-area, velocity of the centre of pressure (COP), gastrocnemius equinus, and gastrocnemius soleus equines are related to calcaneal apophysitis (Sever’s disease) in athletic children.

Methods

This case-control study examined 106 boys enrolled in a soccer academy, including 53 with Sever’s disease and 53 age-matched healthy controls. The dynamic average and maximum peak plantar-pressures, plantar surface contact-area, and velocity of the COP were evaluated with a digital pressure sensor platform. Goniometry was used to measure the ankle dorsiflexion range of motion and thereby identify gastrocnemius equinus and gastrocnemius soleus equinus.

Results

Participants with Sever’s condition had significantly higher BMI and peak plantar-pressures (maximum and average) at the heel (Cohen’s d > 3 for pressures) than the controls. Those with Sever’s disease also had significantly slower velocity of the COP (Cohen’s d > 3). Boys with Sever’s disease were also 8 times more likely to have bilateral gastrocnemius equinus than disease controls.

Conclusions

High heel plantar pressure and low velocity of COP are related to Sever’s condition in boys, although it is not clear whether these factors predispose individuals to the disease or are consequences of the disease. Gastrocnemius ankle equinus could be a predisposing factor for Sever’s condition.

Reliability and validity of the Zebris FDM-THQ instrumented treadmill during running trials

Little is known about the reliability, validity and smallest detectable differences of selected kinetic and temporal variables recorded by the Zebris FDM-THQ instrumented treadmill especially during running. Twenty male participants (age = 31.9 years (±5.6), height = 1.81 m (±0.08), mass = 80.2 kg (±9.5), body mass index = 24.53 kg/m² (±2.53)) walked (5 km/h) and ran (10 and 15 km/h) on an instrumented treadmill, wearing running shoes fitted with Pedar-X insoles. A test-double retest protocol was conducted over two consecutive days. Maximal vertical force (F_max), contact time (CT) and flight time (FT) data from 10 consecutive steps were collected. Within- and between-day reliability, smallest detectable differences (SDD) and validity (95% limits of agreement (LOA)) were calculated. ICC values for the Zebris for Fmax were acceptable (ICC ≥ 0.7) while CT and FT reliability indices were predominantly good (ICC ≥ 0.8) to excellent (ICC ≥ 0.9). The Zebris significantly underestimated Fmax when compared with the Pedar-X. The 95% LOA increased with speed. SDD ranged between 96 N and 169 N for Fmax, 0.017s and 0.055s for CT and 0.021s and 0.026s for FT. In conclusion, Zebris reliability was acceptable to excellent for the variables examined, but inferior in comparison with Pedar-X. With increased running speeds, a bias effect (underestimation) existed for the Zebris compared with Pedar-X.

Biomechanical podiatric evaluation in an Italian cohort of patients with systemic sclerosis: A pilot study

OBJECTIVE

Foot problems are often present in Systemic Sclerosis (SSc) patients, however studies regarding podiatric problems related to SSc are lacking and there are no data evaluating the foot biomechanical changes. The aim of the present pilot study was to evaluate podiatric problems in an Italian cohort of SSc patients by assessing received podiatric services, foot pain and disability and biomechanical foot deformity.

MATERIAL AND METHODS

25 consecutive SSc patients were enrolled from the Division of Rheumatology, University of Florence. All SSc patients were assessed by: Standards of Care for People with Foot Musculoskeletal Health problems: Audit Tool, Foot Function Index (FFI), Weight and non-weight bearing foot joint assessment, (Foot Posture Index (FPI) and Gait Cycle), Health Assessment Questionnaire (HAQ) and Medical Outcomes Survey Short Form 36 (SF-36).

RESULTS

Audit Tool - Only 7 (28%) out of the 25 patients with SSc had a specific podiatric assessment and treatment: no patient received a foot health assessment within the first 6 months of disease diagnosis and no patient received information about foot involvement. 1 patient (4%) received foot assessment every year; 1 patient (4%) received specific information about the disease and 5 patients (20%) received information about the benefits of using adapted footwear and insoles. FFI - Values of pain, disability and activity limitations, reported in FFI, are 4.7±5.1, 5.1±3.2 and 3.2±3.1 (M±DS), respectively. Non-weight bearing foot joint assessment shows a rearfoot varus deformity in 64% of patients, forefoot varus deformity in 42% and 6% forefoot valgus deformity. Weight bearing foot joint assessment, through FPI shows a pronated foot 20% of patients with and 34% with highly pronated overall foot posture. Gait analysis shows that 64% of patients has a contact of the calcaneus in invertion while 36% in eversion. In the midstance, 78% have the foot in pronation and 22% in supination, while in propulsion 12% presents a takeoff of the foot in supination and 88% in the pronation. HAQ result is 1.13±0.80, SFI and SMI scales of SF-36 have scores of 32.38±10.65 and 38.67±11.40, respectively.

CONCLUSION

Our results shows that podiatric problems in SSc patients are common, serious but foot assessment and health care are inadequate. Thus, foot health information should be improved in order to better empower patients to self-manage low risk problems and help identify high-risk problems, which require specialist care.