The Growing Child

Michael G. Vitale, MD, MPH

John M. (Jack) Flynn, MD

David L. Skaggs, MD, MMM

Alain Diméglio, MD¹

James O. Sanders, MD¹

¹Gurus:

Adapted with permission from Alain Diméglio, MD.

General Considerations

To stay out of trouble when treating orthopaedic problems in the growing child, it is important to have a practical understanding of normal growth and development. We do not need to be developmental pediatricians but need to be able to recognize when something is amiss. The pediatric orthopaedic surgeon is often the first to evaluate the child with subtle developmental delays or alternations in growth that may signal an underlying problem. While this chapter will provide an overview of important aspects of growth and development, more specific aspects of growth as they pertain to the spine, leg length discrepancy, and limb alignment are covered in those chapters.

It is important to recognize that the definition of “normal” depends on whether or not you are dealing with an underlying condition. Normal size and normal motor milestones are different for children with Down syndrome, achondroplasia, or Marfan syndrome. In some cases, specific growth charts have been made for these conditions. While our primary role is to treat the musculoskeletal consequence of problems with growth and development, we can help families by having a high level of suspicion and referring these families to their primary care provider, geneticist, or other pediatric specialist.

Recording height and weight is important and not only for the EMR! While growth is fastest in the first 3 years of life and then again at puberty, steady increase in height and weight is expected regardless of age in the skeletally immature child. Any child that is losing weight (not on purpose) over a few months could be showing signs of trouble. Tracking changes in height is especially useful in guiding treatment decisions in the adolescent with scoliosis. Knowing the timing of the growth peak provides valuable information on the likelihood of progression of scoliosis to a magnitude requiring spinal arthrodesis¹ (Table 3-1). Likewise, orthopaedists who are monitoring leg length inequalities find a growth chart or electronic equivalent valuable.

PHYSIS: “FRIEND OR FOE”

Think about what a tough job the physis has! In order to end up with a fully grown, “straight,” and symmetric body, hundreds of physes need to perform perfectly over many years. In a way it is amazing that growth disturbances don’t happen more often. The physis can be both friend and foe and can at times keep us out of trouble but at other times do the opposite.

Orthopaedic surgeons caring for children also need to have a good understanding of the percentage of growth that is contributed by each physis (Fig. 3-1). Such knowledge of normal growth and development helps the orthopaedic surgeon time epiphysiodesis and understand the potential effects of a traumatic growth arrest.

TABLE 3-1 Useful Guides for Childhood Stature and Growth

By the age of 5 y, birth height has usually doubled and the child is about 60% of adult height.
Arm span should be nearly equal to standing height.
The head is disproportionately large at birth.
In the lower extremity, most growth is around the knee; the opposite is true for the upper extremity where most growth comes from the proximal humerus and wrist.
Skeletal maturity varies considerably, so it is critical to consider bone age rather than chronological age especially around adolescence!

Figure 3-1 Percentage contribution of femoral and tibial physes to lower extremity growth. (Adapted with permission from Hubbard EW, Liu RW, Iobst CA. Understanding skeletal growth and predicting limb-length inequality in pediatric patients. J Am Acad Orthop Surg. 2019;27(9):312-319. Copyright © 2019 by the American Academy of Orthopaedic Surgeons.)

While physeal injuries are covered in detail in other chapters in this book, a few general principles will help us stay out of trouble. For example, an understanding of the normal pattern of physeal ossification centers is helpful in diagnosing occult fractures of the elbow and other areas. Fractures of the distal femoral physis result in a 30% to 50% chance of growth arrest, and these patients need careful follow-up. On the other hand, proximal humerus fractures rarely result in significant problems with growth and alignment.

When considering whether to do an epiphysiodesis to treat leg length discrepancy, it is important to understand growth remaining in the opposite leg. The multiplier method allows for a quick calculation of the predicted limb length discrepancy at skeletal maturity, without the need to plot graphs, and is based on as few as one or two measurements. This method is independent of generation, height, socioeconomic class, ethnicity, and race. Paley et al. verified the accuracy of this method clinically by evaluating patients who had been managed with limb-lengthening or epiphysiodesis.²,³,⁴ And, yes, there is an app for that!

Special Considerations for Different Age Groups

THE INFANT

The typical infant is born with flexion contractures. The hips are generally externally rotated. Genu varum and flat feet are normal. On the other hand, asymmetry of any kind should prompt attention. Be alert for possible handedness before the age of 1 year as it may be a sign of hemiplegia or any other unilateral problem. The orthopaedist caring for infants and toddlers should be generally familiar with a series of milestones that can help quickly identify a child who is lagging behind (Table 3-2). Such an understanding of milestones can have an important role in managing a potential musculoskeletal problem, and counseling families as to whether further investigation is needed. A consult with a developmental pediatrician should be if a child is falling short of developmental milestones.

TABLE 3-2 Key Motor Milestones to Keep the Orthopaedist Out of Trouble

Age	Achievement
2 mo	Good head control in prone position; partial head control in supine position
3 mo	Loss of grasp primitive
4 mo	Good head control in supine position; rolls over prone to supine
6 mo	When prone, lifts head and chest with weight on hands; sits with support Loss of Moro primitive reflex Loss of asymmetric and symmetric tonic neck primitive reflex
8 mo	Sits independently; reaches for toys
10 mo	Crawls; stands holding onto furniture Loss of neck-righting primitive reflex
12 mo	Walks independently or with hand support Gain of parachute postural reflex
18 mo	Developing handedness
2 y	Jumps; knows full name
3 y	Goes upstairs alternating feet; stands momentarily on one foot; knows age and gender
4 y	Hops on one foot; throws ball overhand
5 y	Skips; dresses independently