Hallux valgus is a relatively common and multifaceted complex deformity of
the front part of the foot. It is the result of multiple effects of innate (endogenous)
and exogenous etiological factors with different degrees of influence.
The degree of hallux valgus deformity is usually assessed by radiological values
of hallux valgus (HV) and intermetatarsal (IM) angles. The aim of the
paper is to justify the definition of hallux valgus deformity as a function of
one angle, (HVA or IMA), and then to determine the functional connection
and the most suitable function equalizing the values of the angles IMA and
HVA. As hallux valgus is a double angulation deformity, the analytically determined
connection between the HVA and IMA angles reduces the study of
the deformity to the study of function with one argument, and makes the
analysis of deformity changes before and after operative treatment simpler.
For the determined connections between the angles, the values of linear proportionality
coefficients and regression coefficients of corresponding linear
functions of analytical equalization of the value of the IM angle and the degree
of deformity for a given value of the HV angle were experimentally determined.
The obtained results were checked on a sample of 396 operatively
treated hallux valgus deformities. The presented analytical approach and the
obtained functional links of IMA and HVA enable quantitative observation of
the change in the degree of deformity based on the radiologically determined
value of these angles, and the established nonlinear function will be useful for
evaluating the expected value of the IM angle and the degree of deformity
based only on the measured value of the HV angle.
