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First inter metatarsal (IM) angles in Nigerians and their relationship to first metatarso-phalangeal (MTP) joint angle

B C Didia
G S Oladipo
T M Archor
C Agi


Background: No age is immune to the deformity known as Hallux valgus as it has been proven that 50% of adults developed it during adolescence, while 40% of juveniles developed it before the age of 10.5 years.
Aim: To determine from radiographs the normal value of the first inter metatarsal (IM) angle and to establish if there is a relationship between it and the degree of the metatarsophalangeal Joint (MTPJ) angle in Nigerians.
Methods: A total of 364 anteroposterior radiographs of the foot consisting of 135 females and 229 males were employed in the study. Radiographs were selected from Radiology Departments of University of Port Harcourt Teaching Hospital, Port Harcourt, Braithwaite Memorial Hospital, Port Harcourt and Military Hospital, Port Harcourt. IM and first MTPJ angles were measured using the method of Hardy and Clapham.
Results: The mean IM angle in females significantly exceeds that of males and a relationship exists between the size of the IM angle and the first metatarsophalangeal joint angle of Nigerians. The mean first IM angle is 7.62o ± 0.22o for males and 8.58o ±0.25o for females. The difference between sexes was statistically significant (p<0.01).
Conclusion: There is a positive linear correlation between the size of IM angle and the degree of first MTPJ angle. The correlation is much more pronounced in the females (R = 0.34), a difference that we attributed to the effects of more constricting shoes worn by women.

Keywords: First intermetatarsal angle, First metatarsophalangeal angle, Hallux valgus, Hallux varus

PHMJ Vol. 2 (2) 2008: pp. 151-155