Principles and Management of Pediatric Foot and Ankle Deformities and Malformations, 1 Ed.

CHAPTER 1. INTRODUCTION

“Techniques change, but principles are forever.” I do not recall when I first heard that declaration or who in history first stated it, but it has been my mantra for decades. There may be no part of the human body for which the wisdom of those words is more poignant than the child’s foot. With 26 bones, at least 31 articulations, and countless muscle/tendon attachments, the foot is comparable only to the hand as the most complex anatomic region of the musculoskeletal system. This anatomic complexity contributes to the extremely wide variety of deformities and malformations that afflict the foot. And although the incidence of malformations of the foot is comparable to that of the hand, there are far more deformations (deformities) of the foot than the hand.

PURPOSE OF THE BOOK

The foot, and the child’s foot in particular, is a complex anatomic body part with many bones, joints, muscles, and tendons working in concert to provide a stable, but supple, platform that helps it accommodate to the changing terrain below and propel the body in space. There are many congenital, developmental, and acquired deformities, as well as malformations, that challenge the ability of the foot to serve those complex and important functions. There is great variability in the natural history, severity, flexibility/rigidity, age at onset, age at treatment, and rate of progression of these conditions. In addition, the effects of growth and development, as well as the effects of previous treatment, on the common and rare deformities and malformations of the child’s foot make a cookbook approach to management unreasonable. That great variability also makes prospective, controlled studies of treatment effectiveness almost impossible to carry out. Therefore, a principles-based approach is necessary to ensure the best possible treatment outcomes.

The traditional approach to treating foot deformities in children has been based on techniques. There is often a cookbook association of a named operation with a named deformity. Unfortunately, the operation typically addresses only one or possibly two of the multiple deformities that are present. That approach can lead to poor surgical outcomes if the severity and rigidity of the deformities are greater than usual or if additional unrecognized segmental deformities exist. Furthermore, there are many iatrogenic foot deformities and rare idiopathic deformities and malformations for which there are no reported cookbook treatments. Without a thorough understanding of foot deformities and malformations, it is challenging to determine what to do in these situations. Moreover, techniques change because of technologic advances and human creativity. Without a thorough understanding of foot deformities and malformations, it is difficult or impossible to assess and compare old and new techniques. The obvious conclusion is that the management of the varied, and often rare, foot deformities and malformations in children must be based on principles. And principles-based management is dependent on principles-based assessment.

A principle is a basic generalization that is accepted as true and can be used as a basis for reasoning or conduct. The purpose of this book is to present, in one source, the principles of assessment and management of foot deformities and malformations in children and adolescents that have been conceived, developed, organized, and explained by one pediatric orthopedic surgeon with almost three decades of extensive experience studying and treating these conditions. The principles are then applied to the individual deformities and malformations. Finally, detailed descriptions of soft tissue and bony procedural techniques are presented, many of which are difficult or impossible to find elsewhere.

This book is not intended to be encyclopedic but, instead, practical and immediately applicable. Indications for nonoperative and operative management are stressed. Surgical techniques are described and illustrated. Pitfalls and complications of treatment are discussed.

For more detailed information on the definition, epidemiology, etiology, clinical features, radiographic features, pathoanatomy, natural history, and treatment of foot deformities and malformations in children, see my chapter entitled The foot. In: Weinstein SL, Flynn JM, eds. Lovell and Winter’s Pediatric Orthopedics. 7th ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2013:1425–1562. It is a valuable companion resource.

HOW TO USE THE BOOK

Following this introductory chapter, Chapters 2 to 4 elucidate the basic, assessment, and management principles needed to effectively treat foot deformities and malformations in children and adolescents. A thorough understanding of these principles is required before focusing on a particular foot deformity or malformation. In Chapters 5 and 6, each of the major, and some of the minor, foot deformities and malformations is considered in regard to definition, elucidation of the segmental deformities, imaging, natural history, nonoperative treatment, operative indications, and operative treatment. The correction of most foot deformities and malformations involves the concurrent or sequential utilization of more than one soft tissue and/or bone procedure. To avoid redundancy, the procedures are individually described in detail in Chapters 7 and 8. The operative treatment section for each deformity and malformation in Chapters 5 and 6 references the techniques in these final two chapters. The operative treatment section also indicates how the individual procedures are combined and, in some cases, modified for a particular condition.

The references are included at the end of the book, but are not annotated within the text. This is a “how to” book that is based on one surgeon’s knowledge and extensive experience in this field. The principles are original to the author. The techniques are original to the author or the author’s interpretation and/or modification of the originals. The references allow the interested reader to access the original pertinent literature.

Although the numerous images in this book should help clarify the principles and techniques for the reader, observation and manipulation of a life-size foot skeleton model (that is held together by elastic cords) will add three-dimensional clarity and should be used liberally.

To get started, definitions are in order.

Deformity/deformation: A deformity/deformation is a malalignment of relatively normally formed bones at a joint. A deformity can refer to malalignment at a single joint, but in most named deformities of the foot (clubfoot, cavovarus foot, skewfoot, etc.), there are at least two segmental deformities that are often in rotationally opposite directions from each other (see Basic Principle #5, Chapter 2). The malalignment may be (1) structural/rigid, i.e., characterized by restriction of normal joint motion, or (2) flexible, i.e., passively correctable. The latter may be idiopathic or dynamic (due to an underlying muscle imbalance). Structural/rigid and flexible deformities can be congenital, acquired, developmental, idiopathic, iatrogenic, caused by an underlying neuromuscular disorder, or some combination of these.

Malformation: A malformation is an incorrectly created anatomic part. Malformations fall into five broad categories: too large, too small, too many, too few, joined together/failed to separate (Table 1-1).

Congenital mal-deformation: Deformities can be associated with malformations. This is particularly true for malformations in the category of joined together/failed to separate and present at birth, i.e., congenital subtalar synostosis (see Chapter 6). In the flatfoot deformity associated with fibula hemimelia, Apert syndrome, and lower extremity hemiatrophy, there is congenital synostosis of the talus and calcaneus (and also commonly the cuboid and navicular). This is a failure of segmentation (failure of apoptosis) between the involved bones that begins as an extensive synchondrosis and undergoes metaplasia to a synostosis during early childhood. The calcaneus is attached to the talus in a laterally displaced position, creating valgus alignment of the hindfoot without the other components of eversion deformity of the subtalar joint. These rare, congenital, rigid flatfeet with extensive tarsal coalitions should perhaps be called congenital mal-deformations.

Developmental mal-deformation: Congenital subtalar synostosis, a congenital mal-deformation, is quite different from the common, limited-size tarsal coalition. The latter is autosomal dominant, affects up to 13% of the population, and undergoes metaplasia from syndesmosis to synchondrosis to synostosis between the ages of 8 and 16 years, with progressive loss of subtalar motion and loss of longitudinal arch height (see Chapter 5). These are not congenital, though they are genetically programmed to develop. They result in a synostosis, which is a malformation, but not in the usual sense, in that they are not congenital, i.e., present at birth. Perhaps these should be called developmental mal-deformations.

Anatomic variation: And finally, one should be cautious in applying the term deformity to an anatomic variation. Most babies have physiologically normal, asymptomatic flexible flatfeet (see Basic Principle #4, Chapter 2). It is estimated that approximately 20% to 25% of adults have that same foot shape which, according to Harris and Beath, is the normal contour of a strong and stable foot and of little consequence as a cause of disability. Roughly 25% of the flatfooted adults, those with heel cord contractures, have pain (see Chapter 5). Perhaps, a painful flexible flatfoot with heel cord contracture should be called a deformity, and a painless flexible flatfoot without heel cord contracture should be considered merely an anatomic variation.

Though this classification system has never been formally proposed, I will refer to it from time to time in this book.

I hope this book provides the reader with the knowledge and tools needed to meet the many challenges associated with assessing and managing foot deformities and malformations in children.