Page 70 - Tobillo y Pie 9.1

Managing the adult flexible flatfoot deformity. The past, present and the future. An evolution of thinking

substitute for the torn PTT. This of course failed to osteotomy to the FDL transfer as introduced by
recognize the variety of deformities that exist in the Myerson, became a routine part of this reconstruction
AFFD, in particular, the various joints on the medial for many surgeons, and although it addressed the
side of the foot, which can sag or develop arthritis. The valgus deformity of the heel, it still failed to address the
same applied to the various types of abduction of the imbalance of muscle forces on the hindfoot following
forefoot or midfoot where the apex could be either at rupture of the PTT. Stage III consisted of rigid deformity
the talonavicular (TN), naviculocuneiform (NC) or with hindfoot valgus in which the subtalar joint was
tarsometatarsal (TMT) joint. Because of the plethora not correctable to neutral, and triple arthrodesis was
of these surgical alternatives, choosing a procedure was the treatment of choice. While the majority of rigid
confusing. Decision-making does, of course, depend deformities do indeed require a triple arthrodesis, there
on the severity of the deformity, the appearance of the are many additional procedures, which must also be
foot, and the flexibility of the hindfoot and forefoot. considered as part of the spectrum of a rigid flatfoot
Perhaps the most important aspect of decision- deformity. Myerson subsequently added a Stage IV to
making is the presence of flexibility in the hindfoot. this rudimentary classification system which included
Specifically, is the subtalar joint completely correctable valgus deformity of the ankle associated with a rupture
into a neutral position with or without supination of the deltoid ligament. (5)
of the forefoot? If such a reduction is possible, can it A classification system of the flatfoot is only helpful
be achieved without associated significant forefoot if it describes and characterizes all types of deformity,
supination? The overall approach to correction of and provides a corresponding treatment alternative
deformity is therefore based on the flexibility of the for every aspect of deformity. We recognized that few
foot; the presence of rupture of the posterior tibial adult acquired flatfoot deformities could be placed into
tendon, the spring ligament, or the deltoid ligament; one of the four stages described above. Probably the
and the presence of any arthritis or secondary deformity most detailed and clinically useful system recognized
of the midfoot. To understand this further, one must is the one devised by Myerson et al. in 2007, which
study the classification systems for the flatfoot that is described in more detail below. This system
(7)
have been used over these past decades, since these describes the characteristic clinical and radiographic
give an indication as to what the surgical options were findings for each stage and the treatment algorithm,
considered historically for each deformity. which should be adopted.
The first attempt at a classification of the adult Stage II: PTT rupture with flexible flatfoot
acquired flatfoot was by Johnson and Strom in the late
1980’s. This was quite simplistic, and divided the This stage is characterized by a collapse of the
(3)
problem into three stages: Stage I was considered to longitudinal arch, hindfoot valgus, weakness of inversion
be an early flatfoot associated with tenosynovitis but in a plantar flexed foot and inability to perform a single
with minimal flatfoot deformity, and if non surgical heel rise test. The pathology is a weak or ruptured
treatment failed, they proposed a tenosynovectomy tendon but the hindfoot is still mobile. It is further
of the PTT. This however completely ignored the fact divided into three sub-stages with the first sub-stage
that tenosynovitis is invariably associated with a slight being further subdivided into two categories.
flatfoot and a tight gastrocnemius. Therefore, we would Stage IIA (hindfoot valgus): This stage is characterized
now routinely add a medial translational calcaneus by a flexible hindfoot valgus. Once the heel is reduced
osteotomy with or without a gastrocnemius recession to to neutral position, the forefoot supination is either
the tenosynovectomy for early stage disease. Their stage II minimal or completely reducible (Stage IIA 1) or fixed
consisted of a flexible flatfoot deformity, but the type (Stage IIA 2). Forefoot supination occurs because the
of flexibility and the apex of the deformity was never forefoot always has to remain plantigrade regardless of
characterized. For most of the 1980’s and 1990’s this what is happening in the hindfoot. So, if the hindfoot
type of deformity was treated with a flexor digitorum moves into valgus, the forefoot has to adapt to these
longus (FDL) transfer. Some surgeons transferred the changes allowing the medial and lateral columns of
FDL into the navicular, and some as a tenodesis to the the forefoot to remain in contact with the floor. If one
ruptured PTT, but no recognition of the different types reduces the heel into a neutral position, then these
of midfoot and hindfoot deformity was made at this changes become apparent with a supination of the
time. The addition of a medial translational calcaneus medial forefoot.
60 Tobillo y Pie 2017;9(1):58-68