Reproducibility of newly developed spinal topography measurements for scoliosis.

OBJECTIVE: In an effort to limit exposure to ionizing radiation and fully characterize three dimensional changes in the spine of patients with scoliosis reliable non-invasive methods of spinal back contour analysis (Milwaukee Topographic Scanner) (MTS) have been developed. STUDY DESIGN: The current study compares spinal topography measurements among different subject positions and evaluates the reproducibility of the system for both inter-rater and intra-rater reliability. METHODS: A dummy cast (plastic cast) of one patient with adolescent idiopathic scoliosis was created in order to test the reliability of the MTS. The dummy cast was positioned and rotated in 3D while scanned by two investigators using the MTS. A total of twelve parameters including Q-angle (an analog to X-ray's Cobb angle) were extracted. RESULTS: All measurements of intra-rater and inter-rater reliability were excellent (Intraclass Correlation Coefficients ranging from 0.89 to 0.99) with the exception of Pelvic Tilt (intra-rater ICC is 0.61) and lordosis angle (inter-rater ICC is 0.82). No significant variability among investigators was observed for all tested metrics. No significant variability due to position was observed for the majority of back contour measurements but there were significant changes in the T1-S1 angle, T1-S1 deviation, T1-NC angle, T1-NC deviation, and Back Height metric (p< 0.05). CONCLUSIONS: The MTS is a reliable method of raster stereography in the measurement of the back contour, which will help monitor the progression of children with idiopathic scoliosis and reduce the use of X-rays.

Motion of the multisegmental foot in hallux valgus.

BACKGROUND: Hallux valgus is a common condition characterized by lateral deviation of the large toe and medial deviation of the first metatarsal. While some gait analyses of patients with hallux valgus have been performed using plantar pressures, very little is known about the kinematics of gait in this population. The purpose of this study was to evaluate triplanar kinematics in patients with hallux valgus using a multisegmental foot model. MATERIALS AND METHODS: A 15-camera Vicon Motion Analysis System was used to evaluate the gait of 38 feet in 33 patients with mild to severe hallux valgus. The Milwaukee foot model was used to characterize dynamic foot and ankle kinematics and temporal-spatial parameters. Values were compared with normal subjects. Outcomes were evaluated using the SF-36 assessment tool. RESULTS: Patients with hallux valgus showed significantly decreased velocity and stride length and prolonged stance. Significant alterations in gait kinematics were observed in various planes in all segments (hallux, forefoot, hindfoot, and tibia) of the foot and ankle, particularly in the ranges of motion of the hallux and the forefoot. CONCLUSION: The results demonstrate significantly altered kinematic and temporal-spatial parameters reflective of reduced ambulatory function in patients with hallux valgus. As reports describing multisegmental foot and ankle kinematics in this population are limited, this study is valuable in characterizing gait in patients with hallux valgus. CLINICAL RELEVANCE: A better understanding of altered gait dynamics of the multisegmental foot in patients with hallux valgus provides valuable insight on how distal pathology affects proximal segments.

Multisegmental foot modeling: a review.

Over the past two decades, a number of multisegmental foot models have been developed in order to characterize foot kinematics. This paper reviews methods of multisegmental foot modeling, technical elements of the models, select clinical applications of the models, and future directions in this area of research. Technical areas discussed include angular derotation mechanisms and capture technology. Models discussed address two-, three-, four-, five-, and nine-segment approaches. Additional models which address foot segments using other definitions, are also discussed. Clinical applications of multisegmental foot models include pathologic gait characterization in rheumatoid arthritis, posterior tibial tendon dysfunction, and hallux rigidus. Areas of continued development, including soft tissue artifact and nomenclature, are also discussed.