Three-dimensional analysis of different first metatarsal osteotomies in a hallux valgus model.
BACKGROUND
This study evaluates and compares three-dimensional (3-D) changes in geometry of the first metatarsal (MT1) independent of soft tissue corrections of 5 common osteotomies: three distal (Chevron, Mitchell, and Wilson), one proximal (Stephens basal), and one combined proximal/distal (Scarf), using standardized synthetic bone models.


METHODS
A digitizing system was used to measure and record points on the synthetic bone models in 3-D space. Computer vector analysis calculated 3-D rotations and translations of the MT1 head plus the conventional intermetatarsal angle (IMA) and distal metatarsal articular angle (DMAA).


RESULTS
The Wilson and Mitchell's osteotomies produced significant shortening (p < 0.001) in contrast to the three other osteotomies. All the osteotomies produced a reduction in the 3-D IMA. The Scarf and Stephens basal osteotomies reduced the DMAA. All of the osteotomies resulted in lateral translations and depression of the MT1 head. While there were no significant (p > 0.05) translational differences between the Scarf and Stephens basal osteotomies, there were rotational differences, with the Stephens basal producing significantly more plantar flexion (p = 0.000) and pronation (p < 0.001) than the Scarf.


CONCLUSIONS
This geometric study indicated many of the MT1 head changes following metatarsal osteotomy to be out-of-plane translational and multiplanar rotations which cannot be determined using AP radiographs alone.


CONCLUSIONS
We advocate judicious choice of osteotomy to achieve the desired correction of hallux valgus in each individual.
Northern General Hospital, Sheffield Foot & Ankle Unit, UK.
Avril D
AD
McCarthy
Mark Bowen
MB
Davies
Kevin R
KR
Wembridge
Chris
C
Blundell
D001837:Body Weights and Measures; D006215:Hallux Valgus / Q000000981:diagnostic imaging / Q000473:pathology* / Q000601:surgery*; D006801:Humans; D021621:Imaging, Three-Dimensional; D008682:Metatarsal Bones / Q000000981:diagnostic imaging / Q000473:pathology* / Q000601:surgery*; D008683:Metatarsophalangeal Joint / Q000000981:diagnostic imaging / Q000473:pathology; D008954:Models, Biological; D010027:Osteotomy / Q000379:methods*; D011859:Radiography; D015203:Reproducibility of Results