First Ray Model Comparing Normal and Hallux Valgus Feet - Computational Biomechanics of the Musculoskeletal System - page 50

4.1 IntroduCtIon
4.1.1 B ackGround
Hallux valgus is an acquired deformity of the toes, characterized by lateral deviation of the hallux
(hallux abducto valgus) and medial deviation of the first metatarsal (metatarsal primus varus).
Another term, bunion, is often used to describe the same condition, more prominent on the enlarged
and chronically swollen medial projected eminence. The condition could lead to disruption of the
alignment of the first metatarsophalangeal joint. Eventually, the patient complains of pain and,
in severe cases, joint dislocation may occur. Impaired gait and poor balance are also common
symptoms in elderly patients (Abhishek et al. 2010; Cho et al. 2009; Koski et al. 1996; Mann and
Coughlin 1981; Menz and Lord 2001a, 2001b; Tinetti, Speechley, and Ginter 1988).
Genetics and sexual dimorphism are two important intrinsic factors leading to hallux valgus, and
family history shows a strong association with the prevalence of hallux valgus (Piqué-Vidal, Solé,
and Antich 2007; Wu and Lobo Louie 2010). Genetics can have a substantial influence on meta-
tarsal shape, arch height, and hypermobility (Bonney and Macnab 1952), with women being two
to three times more susceptible than men (Nguyen et al. 2010; Roddy, Zhang, and Doherty 2008).
Gender imposes differences in anatomy (Gutiérrez Carbonell, Sebastia Forcoda, and Betoldi Lizer
1998), bone morphology (Ferrari and Malone-Lee 2002), bone alignment (Ferrari, Hopkinson,
and Linney 2004), ligamentous laxity (Wilkerson and Mason 2000), and first ray hypermobility
(Coughlin and Shurnas 2003). Other publications have focused on extrinsic factors, such as foot-
wear, occupation, and obesity (Coughlin and Jones 2007; Frey and Zamora 2007; Greer 1938).
Hallux valgus is one of the most common foot complaints (Vanore et al. 2003). Research under-
taken in the United Kingdom reported a high prevalence of 28.4% in adults (Roddy, Zhang, and
Doherty 2008). Owoeye et al. (2011) surveyed secondary school and undergraduate students and
found a prevalence of 15.4%, with 9% reporting pain and 14% reporting an inability to walk for a
prolonged period. Research targeting the elderly also demonstrated a high prevalence of 74% (Menz
and Lord 2005). The high prevalence of hallux valgus imposes an unnecessary economic burden
on the health care system and society in general. Thompson and Coughlin (1994) estimated that
there were 56,500 bunionectomies performed in the United States in 1991, with 27% of all forefoot
surgeries being undertaken to correct hallux valgus deformities. A study conducted in Australia
(Australian Bureau of Statistics 2008) reported an average of 22 absent days following first metatar-
sophalangeal joint surgery, with a productivity loss of AUS$ 3,852 and the average hospitalization
costing AUS$ 3,764.16 (Access Economics 2008; Courtney, Matz, and Webster 2002; Grimm and
Fallat 1999; Mathers et al. 2001).
Though hallux valgus and its surgical correction are routine occurrences, the associated fail-
ures, complications, and recurrences remain. Complication rates range from 10% to 55% (Scioli
1997), and recurrence rates could be as high as 16% (Caminear et al. 2012; Lehman 2003). Failure
rates could surpass 75% with soft tissue correctional procedures, such as the McBride procedure
(Coughlin and Mann 2012). Osteotomy and arthrodesis could lead to over-correction (Easly et al.
1996), metatarsalgia (Wanivenhaus and Feldner-Busetin 1988), avascular necrosis, and arthrosis
(Coughlin and Mann 2012).
4.1.2 B iomecHanical r eSearcH on H allux V alGuS and i tS i nterVention
Biomechanical research on hallux valgus and its correction has been conducted with the aim of
better understanding the pathogenesis of the disease and improving treatment outcomes. The con-
cept of first ray hypermobility, introduced by Morton (1928) and Lapidus (1956), has been hotly
debated in explaining hallux valgus and in selecting interventions (Faber et al. 2001; Glasoe
et al. 2002). The importance of stability was stressed, as advocated by the arthrodesis procedure
(Lapidus 1956). The evaluation of stability was also included in other studies on the osteotomy of