[Radiographic analysis of the orientation of the distal articular surface of the first metatarsal in the horizontal plane].

PURPOSE OF THE STUDY: The lateral obliquity of the distal metatarsal articular surface is a predominant anatomical factor in hallux valgus pathology. It is important to know its normal angular value.

MATERIAL-

METHODS

The study included 105 feet without any pathology (48 females and 57 males; 53 left and 52 right between 15 and 72 year old). Weight-bearing, anteroposterior X-rays of the foot was made. We measured the distal metatarsal articular angulation (DMAA), the intermetatarsal angle, the metatarsophalangeal angle, the obliquity of the metatarsocuneiform joint and the length of the first and second metatarsal, and the length of the hallux.

RESULTS

The main value of the DMAA was 5.78 degrees in our study, 6.79 degrees for women and 4.92 degrees for men. There was no difference between left and right side, no correlation between intermetatarsal angle and DMAA, neither between biometrics parameters and DMAA.

DISCUSSION: Our results confirm the Richardson study on cadaver with a main value of 6 degrees for the DMAA. The DMAA value increases in women and it does not increase proportionaly to the intermetatarsal angle; it increases with the value of the metatarsophalangeal angle. All these points have to be taken in consideration in hallux valgus evaluation.

CONCLUSION

The distal metatarsal articular surface has a lateral obliquity of 5.78 degrees. It must be evaluated before surgical correction of hallux valgus, in order to decrease recurrence rate of this pathology and iatrogenic deformity.