- oblique diaphyseal osteotomy that is directed proximal-plantar to distal-dorsal;
- long dorsal shelf of bone supports the distal fragment, making dorsal displacement of the osteotomy unlikely;
- type of intrinsically stable metatarsal osteotomy (weightbearing on the foot compresses the osteotomy)
- other types of intrinsically stable osteotomies include the proximal chevron and scarf procedures.
- modified osteotomy:
- osteotomy is extended proximally to enable greater IMA correction (more proximal center of rotation);
- second cut through the plantar metaphyseal cortex completes the osteotomy to prevent extension into the tarsometatarsal joint;
- oblique, bicortical osteotomy is made from the plantar and proximal metaphysis to the distal third of the diaphysis
- angle osteotomy tof 10 to 15 degrees in the sagittal plane;
- osteotomy is angled neutral to the axis of the foot, which can be clinically judged by orienting the saw blade towards the fifth metatarsal shaft;
- second cut is made with a smaller, 5-mm short saw transversely at the plantar metaphysis to complete the osteotomy;
- fragment is mobilized by plantarflexing distal fracture fragment along with longitudinal traction;
- correction of IMA: distal fracture fragment is rotated and translated laterally;
- fixation is achieved with two bicortical screws applied from dorsal to plantar;
- capsule is tightened and sutured back to the first metatarsal head (thru a hole is drilled at the dorsomedial aspect at the metaphyseal junction)
Die operative Behandlung des hallux Valgus. Mau C, Lauber H. Deutsche Zeit Orthop. 1926;197:361-377.