Foot Deformity Correction Planning in the Sagittal Plane Based on the Vitruvian Foot First Metatarsal Mechanical Axis and Calcaneus Anatomic Axis.

The aim of the study was to test a novel planning method for simultaneous midfoot and hindfoot deformity correction, based on reference lines and angles (RLA) of the talus, calcaneus and first metatarsal in 64 normal radiographs from 55 patients. Talus Joint Line (TJL), from the border of the articular surface of the talus and the posterior process of talus, and mechanical axis of the first metatarsal form the mechanical Lateral Talometatarsal Angle (mLTMA) = 23.6º (±3.2). The length of the first metatarsal line was measured from its intersections with the TJL and first metatarsal head and it was 4.3 (±0.94) times longer that TJL (k). For hindfoot correction planning, we used an axis of the calcaneus formed by a line starting at the middle of the back of the calcaneal tuberosity and going perpendicular to a line from the top point to the bottom point of the calcaneal tuberosity. The intersection of the calcaneal line and the anterior continuation of TJL form the lateral heel angle (LHA) = 15.2º (±3.4).The following parameters were identified: the length from the intersection point of the lines and anterior point of TJL was 2.56 ± 1.1 longer than TJL (k1). The length from the intersection point and posterior border of the calcaneus was 4.59 ± 1.0 times longer than TJL (k2). Planning using the new method was demonstrated and confirmed on 3 case examples. A novel method for analysis and planning of midfoot and hindfoot sagittal plane deformity correction may be used separately or simultaneously for complex deformity correction.

Foot Deformity Correction Planning in the Sagittal Plane Based on the Vitruvian Foot First Metatarsal Anatomic Axis.

The aim of this study was to test a novel planning method for midfoot deformity correction, based on reference lines and angles (RLA) of talus and first metatarsal of 64 normal radiographs from 55 patients. The anatomic lateral talometatarsal angle (aLTMA), resulting from the intersection of talus joint line (TJL), from the border of the articular surface of the talus to the posterior process of talus, and the anatomic axis of the first metatarsal, was 28.5° ± 4.5°. The intersection of those 2 lines divided the TJL in 2 segments (ac and ab) with the ratio k1 = 0.7 ± 0.3. The length of the first metatarsal line was measured from its intersection with the TJL and first metatarsal head, and it was 3.6 times longer that of the TJL (k2). To analyze foot deformity, we propose to draw the TJL line as follows. Use the k1 ratio to determine the point where the aLMTA intersects the TJL. From this point, an idealized anatomic first metatarsal line should be drawn, at 28.5° from the TJL. The distal end of that line is based on the k2 ratio (3.6 × TJL length). Next, the actual anatomic lateral talometatarsal line of the deformed foot is drawn. The intersection between these 2 lines identifies the apex and magnitude of the deformity. Deformity correction planning using the proposed method was demonstrated and confirmed in 2 cases. A reference method for analysis and planning of midfoot sagittal plane deformity correction independent of foot position relative to the ankle joint or the presence of concomitant hindfoot deformity appears promising for future investigation and use.

New Sagittal Plane Reference Parameters for Foot Deformity Correction Planning: The Vitruvian Foot.

Currently available methods for analysis and planning of post-traumatic or congenital deformity correction of the foot have some limitations. The aim of this retrospective study was to establish reference lines and angles (RLAs), and the resulting ratios, based on reproducible anatomic points on sagittal feet radiographs. The key starting point of our evaluation was the previously undescribed length and position of the talus joint line (TJL), from the border of the articular surface of the talus and the posterior process of talus. First, we calculated the relationships between the TJL and the axes of the foot, particularly the anatomic and mechanical lateral talometatarsal angle axes of the first metatarsal. Then, we assessed the relationships with the calcaneus, particularly the lateral heel angle. Finally, we calculated the parameters (angles and coefficients k) derived from the TJL and the foot-bearing points (foot quadrilateral). A total of 64 normal radiographs from 55 patients were analyzed. The values that resulted are as follows: anatomic lateral talometatarsal angle = 28.5° ± 4.5°, mechanical lateral talometatarsal angle = 23.6° ± 3.2°, lateral heel angle = 15.2° ± 3.4°, foot quadrilateral: abc = 144.6° ± 9.4°, bcd = 31.3° ± 2.6°, cda = 79.2° ± 9.8°, dab = 105.0° ± 8.3°, k1 = 3.09 ± 0.4, k2 = 3.77 ± 0.78, and k3 = 1.56 ± 0.24. Sagittal plane reference lines and angles are proposed, providing quantitative values for reference. These parameters have the potential to be easily implemented in foot deformity analysis and correction planning.