Purpose: We present a new basilar osteotomy we have called TRADE. This osteotomy uses a single flat-oblique cut to achieve lateral basimetatarsal translation with lowering and derotation.

Material: The ATLAS system was used. This system includes a four point axial staple for the phalanx and a staple plate for the metatarsus. The staple plaque was designed around the tibial osteotomy plates. It is composed of a straight plate screwed to the diaphysis. It carries two spikes at variable angles that penetrate the epiphysis perpendicularly. The desired angle is measured peroperatively and the plate is bent appropriately using a graduated template. Application of the staple plate then imposes the exact correction.

Method: We tested the basal osteotomy on five anatomic hallux valgus specimens, including one fresh specimen. We also reviewed 125 files of patients who underwent double flat-oblique osteotomy fixed with the system. Each type of hallux valgus was defined pre- and postoperatively, clinically and radiologically: four views, three to determine the orientation of the deformity in the three planes and a fourth one to assess reducibility. The operative technique involved four times. The first was often not necessary: lateral release, depending on the degree of retraction on the reduction view. The second time, the medial chevron osteotomy of the first phalanx, was almost always needed. The third time was the basimetatarsal ostetomy; the flat-oblique direction was determined from an abacus taking into account three variables: varus, rotation, lowering. The fourth time, exostosectomy with capsule retention, was not always needed. The patients experienced little pain postoperatively when the procedure was limited to the two osteotomies without affecting the soft tissues. For the 125 cases, intermetatarsal deviation was improved from 18°67 to 6°86, metatarsophalangeal angle from 33°59 to 11° and pronation from 13°42 to 0°72.

Conclusion: The TRADE osteotomy allows correction in all three planes. Correction is particularly precise in the frontal plane where the risk of undercorrection and recurrence is high. The procedure can be modulated according to the radiological presentation and can be limited to two osteotomies using short skin incisions without opening the joint.

Purpose: All displacements can be described with x, y, z coordinates. We propose an anterior view of the first metatarsal associated with a peroperative test to determine the precise position in the frontal plane, both statically and dynamically. Lateral release is an important step in surgical treatment of hallux valgus. Both the extent of release and the potential benefit of no release must be carefully evaluated. We propose a view allowing an assessment of the metatarsophalangeal reducibility.

Material and method: Peroperative test. This test explores cuneometatarsal laxity. We conducted a prospective study in 100 cases. A 12/100 pin was used to immobilise the first cuneiform and a 20/100 pin was placed in the base of the first metatarsal. A third distal pin in the neck was used to pivot the bone on its axis. A small protractor was used to measure the angle by projection with ±2.5° precision.

Modified Guntz view. This is a weight-bearing anterior view of the first metatarsal. The cassette is positioned posteriorly. The patient stands with the heal raised 40 mm on a 20mmx20mm plexiglass bar. The metatarsal diaphysis must appear perfectly vertical. An isosceles triangle is constructed on the articular facets; the base of the triangle is perfectly horizontal and defines the pronation-supination angle. We made 100 measurements and checked correlation with the peroperative test.

Reduction view. A Zimmer brace was used to reduce the varus metatarsus and adduct the toe. The metatarsophalangeal angle and the position of the sesamoids were used to assess reducibility.

Results: Pronation and/or pronation instability was = 10° in 96% of the patients. The reduction view enabled classifiation by three grades of reducibility.

Discussion: Our contribution is determining for correction of displacements taking into account the frontal plane. No other study has shown so clearly the existence of metatarsal pronation. We also confirmed the presence of a large proportion of cuneometatarsal instability. The extent of lateral release or the potential benefit of no release can now be assessed.

Conclusion: A certain number of failures have undoubtedly been related to neglect of the parameters studied here. It is indispensable to explore the frontal plane and the dynamic parameters before establishing indications for new flat-oblique metatarsal osteotomies using conventional or minimally invasive techniques.