Paediatric limb deficiency

Children are not little adults

Though there are some areas of general overlap, the management of limb loss in children is quite different to adults. Key differentiations include:

  1. A high proportion of congential limb deficiency versus acquired amputation (~3:1)
  2. Terminology / Classification
  3. An immature skeleton
  4. Adjustment
  5. Habilitation versus rehabilitation
  6. Growth and development considerations
  7. Paediatric distinctions when undergoing amputation

Congenital versus acquired loss

Even with nomenclature, children and adults differ when it comes to describing limb loss. In paediatrics, the term ‘amputee’ or ‘amputation’ is replaced with limb difference or limb deficiency, as the majority of children with limb loss are born this way (ie. congenital). The proportion of congenital versus acquired limb deficiency can range between 60:40 up to 75:25.

For the proportion of children that suffer an acquired loss, the primary causes are:

  1. 75% traumatic (eg. lawn mower, farm machinery, motor vehichle accidents, etc). These losses are usually unilateral; 60 % are often lower limb with a distribution of Transtibial > Transfemoral > Transradial > Ankle disarticulation.
  2. Of the remaining 25% of acquired loss, malignancy and infection rank highly.

Terminology/Classification

Congenital limb deficiency simply means the partial or total absence of a limb at birth. Classification/description of these deficiencies has been more challenging than simply stating transfemoral or transtibial amputation levels for example in the lower limb. A variety of limb classification systems have been used over the years, including (Frantz and O’Rahilly 1961; Henkel and Willert, 1969; McCredie 1974; and Swanson 1976). The current and accepted form of classification that has been adopted internationally since 1998 and is the ISPO classification system. This form of classification utilizes anatomical and radiological evidence for describing the limb deficiency. It states whether the deficiency occurs in a transverse or longitudinal orientation and which anatomical structures are partially or totally absent.(ADD REFERENCE +/- PICTURES)

Growth and Development

The management of paediatric limb deficiency requires a longitudinal outlook. This is to take into account the many development stages children go through from 0-18yrs, growth spurts and the need for education and anticipatory guidance for the family.

Unlike adult prosthetic prescription, a child may undergo a vast array of prosthetic changes as they grow eg. stumpies to extension prostheses with feet, to single axis knee units, to polycentric knee units, etc.

On top of the management of prosthetic alterations to match growth and cognitive development, there are the skeletal immaturity factors that need to be monitored throughout childhood (ie. Growth spurts, terminal overgrowth, limb length discrepancies, etc).

Possible reasons for review through a paediatric limb deficiency service:

  1. Prosthetic provision
    • Interim prosthetic program for assessment of prosthetic proficiency
    • Definitive prosthetic prescription
    • Prosthetic review (eg. addition or change in prosthetic components)
  2. Prosthetic training
    • Initial prosthetic (interim program)
    • Specific task (eg. upper limb deficiency)
    • Specific componentry eg. myoelectric training
    • Developmental training (eg. walking, running, etc)
    • Recreational prostheses (eg. musicianship)
  3. Developmental reviews
    • Key stages of development (eg. 0-1yr, pre schooling, growth spurts, etc)
  4. Assistive and Adaptive Devices (particularly for children with upper limb deficiencies)
  5. Psychosocial support
    • Antenatal counseling
    • Pre amputation counseling
    • Issues of bullying, body image, etc.
    • Peer support
  6. Referral for genetic counseling
  7. Pain management
  8. Orthopaedic referral / collaboration
    • Pre amputation planning
    • Timing of epiphysiodesis
    • Assessment and management of terminal overgrowth
    • Conversion amputation
    • Asymmetric deformity progression
    • Considerations for limb lengthening
  9. Stump care (eg. skin breakdown/wound management)
  10. Pain management
  11. Anticipatory guidance (eg. medical, prosthetic, psychosocial, recreational, etc).

An Immature skeletal system

As is obvious, in paediatrics we are dealing with an immature skeletal system and hence issues related to growth are of primary importance. From a simple prosthetic perspective, children require more frequent prosthetic changes. In adult populations, replacement of prostheses may occur once every three years, whereas for children it is more often every year and more frequently in the early years and during adolescent growth spurts.

With the rapid changes in growth there are also biomechanical and orthopaedic challenges throughout development that need to be anticipated and managed.

With congential limb deficiency, issues regarding limb reconstruction and/or limb lengthening are discussions that are required for a variety of limb deficiencies eg. Proximal Femoral Focal Deficiency; Congenital short femur, Longitudinal deficiency of the fibula.

Many children may choose the path of limb reconstruction rather than an amputation (commonly known as a conversion amputation). However, should the limb reconstruction path not deliver the desired goals of the child, family and treating team, then a switch to the conversion amputation may occur later in childhood.

Appropriateness and timing of conversion amputations is another area of collaboration between orthopaedic and rehabilitation teams.

When considering amputations, preservation of joints remains a common objection. However due to the immaturity of the skeletal system, issues such as terminal overgrowth and the maintenance of growth centres arise. In paediatrics, it is preferable for amputations to occur through joints (disarticulations) rather than through the diaphysis. This principle may lead to less cosmetic outcomes (ie. the bulbous shape of the distal stump), however the preservation of growth centres and avoidance of terminal overgrowth issues mean a better biomechanical outcome in the future and less surgical intervention throughout childhood.

In the event of amputations that do occur through the diaphysis (eg. trauma), then terminal overgrowth become issues that need to be carefully monitored through until skeletal maturity.

The theory behind terminal overgrowth appears to be that the cut bone is trying to create callous (as in after a fracture). This overgrowth tapers and causes distal stump pain. Clinically, it can be identified by the tapering shape of the distal stump; a bursa can often be felt under the most distal point and if severe, the area can feel warm and appear red. An x-ray is often requested to confirm terminal overgrowth.

Adjustment

Congenital Limb Deficiency

  • In the paediatric population, because the majority of children are born with limb deficiency, there is little adjustment to body image for the child. However with those that acquire an amputation (be it through a conversion amputation or traumatic amputation), the issue of adjustment does have to be addressed.
  • Though children may not go through a period of adjustment, parents and extended family members definitely do and hence support for these family members is paramount in the early phases.
  • Ideally, if the limb deficiency is identified in pre-natal scanning, an early referral helps the clinic team meet with the family prior to birth to help address the concerns and questions parents and extended family may have.
  • A follow up review is also advisable as soon as practicable after birth to allow the family further opportunity to discuss concerns and queries.

Congenital Limb Deficiency undergoing conversion amputation

  • Where a planned amputation occurs (ie. Conversion amputation), then pre-amputation counseling is carried out so that the child and family can adjust to the upcoming. This is often carried out with the use of therapy dolls and play therapy to illustrate the level of amputation and the use of a prosthesis in future life.
  • The period and inclusions of pre-amputation counseling varies for each child and family. Meeting another child and family who have gone through the same or similar process can be beneficial. It assists the child to see what life after enduring the impending surgery.
  • Pre-amputation counseling also includes clear guidance about the various phases the child and family will go through (ie. Pre-amputation planning, surgical admission, post-operative healing, stump bandaging, pre-prosthetic casting, prosthetic fitting, prosthetic rehabilitation and where appropriate participation in recreational and leisure pursuits).
  • Post operative, medical (pain relief), physical (desensitization, contracture prevention, early mobilization, etc) and psychosocial support are utilized to continue to address the issues around adjustment.

Traumatic Amputation

  • In the event of traumatic amputations there is often no time to for counseling pre-operatively.
  • The key factors that assist in adjustment often include timely support and again guidance as to the various phases that follow surgery.
  • In the post-operative phase, a team approach is adopted to address pain from the surgery, phantom sensation and phantom pain. In children phantom pain is not usually a long standing issue, however in the traumatic cases (and long standing tumours), anecdotally, there is a higher likelihood of phantom pain.
  • In traumatic cases, a greater emphasis post operatively on medical (pain relief), physical (desensitization, contracture prevention, early mobilization, etc) and psychosocial support is needed to aid in adjustment due to the absence of minimal input that can be given in the pre-amputation phase.

With children and families, many childhood milestones, will cause a recurrence of grief and adjustment. Anticipatory guidance is important as a child enters child-care, the first year of schooling, sporting and recreational pursuits, etc.

The focus on family adjustment is key as the child often reflects their adjustment to their limb deficiency from those that are significant in their lives (parents, grandparents, older siblings).

‘Habilitation’ versus Rehabilitation

Prosthetic rehabilitation in children is often more aptly described as ‘habilitation’ as many of the skills taught are newly acquired rather than needing to be reacquired as in adult rehabilitation.

Decision making around prosthetic prescription and rehabilitation are often guided by a combination of factors. Initial prescription may revolve around physical development (eg. ‘fit to sit’ for upper limb deficiencies; ‘pull to stand’ for lower limb deficiencies), but the component and rehabilitation approach often are influenced by cognitive development.

For children receiving their first limb, the prosthesis is seen as a tool that can assist in play (eg. for being able to stand and cruise, reach toys that are higher, etc). It is often recommended to the family that the limb remain in the toy box when not in use, so that the child develops positive associations with the limb.

For children who have a lower limb deficiency, after progressing through the developmental sequences prior to upright mobility, the issue with prosthetic rehabilitation is often that children ‘get up an go’ and hence this period of input requires adequate understanding of developmental progressions without immediately seeking a mature gait pattern. As children mature, refinement of gait can be made, but therapy is again tailored to their level of development.

The primary role of paediatric prosthetic rehabilitation is not so much rehabilitation but anticipatory guidance to assist the child and family problem solve upcoming developmental milestones eg. growth spurts, commencement of schooling, engagement in sports and recreation, etc.

Paediatric distinction when undergoing amputation

Preoperative Phase

  • As indicated in the ‘Adjustment’ section, where possible (planned amputations) children and families require a developmentally appropriate approach to preoperative counseling. It involves not only the child, but also parents siblings, grandparents and other significant members of the family unit.
  • All members of the team are often involved in this phase
    • Medical (appropriate information and guidance, pain management, etc)
    • Social Worker (preamputation counseling)
    • Occupational Therapist (preamuputation counseling, play therapy, home modification and/or equipment planning).
    • Physiotherapist (preamputation counseling, physical preparation, equipment planning, guidance through the various phases to follow)

Pain management involves the pre-surgical commencement of medications that may limit post-operative phantom limb pain eg. Gabapentin.

Surgical Principles

As indicated in the ‘Immature Skeletal System’ section, the principles that guide amputation levels are different to the adult population:

  • Preserving growth centres is a key principle that both limits the discrepancy between limbs and allows for greatest mechanical advantage as the child grows.
  • Preservation of joints is a key principle, much like in adults, however in paediatrics it is taken one step further, in that operations such as a rotationplasty have been developed where ankle joints can substitute as knee joints.
  • Where the joint cannot be saved, amputations are preferable through joints rather than through the diaphysis. The primary reasons for this surgical principle is that it preserves growth centres and prevents risks of terminal bony overgrowth. In adult populations amputations through the diaphysis are preferred due to their cosmetic appearance and prosthetic socket design.

Post Operatively

  • Paediatric populations rarely have the list of comorbidities of adults and hence post-operative issues around wound healing are more related to the child’s activity rather than inactivity.
  • Children heal relatively quickly and can be out of hospital within a matter of days to a week.
  • Faster healing also progresses them through their post operative phase sooner and it may be as soon as 10 days post-operatively when sutures are removed and shaping of the stump may commence.
  • Unlike adult populations, where shrinker socks appear to be more readily used, these socks rarely are appropriate or available in paediatric sizes. Often due to the uniqueness of the stump because of its anatomy (ie. Congential limb deficiencies), stump bandaging is utilized in the pre-casting phase.

Prosthetic Provision

  • Prosthetic fitting can occur as early as 3 weeks following surgery if no complications are encountered and the stump has little oedema.
  • Paediatric prosthetic design requires a high degree of adjustability, need to be lightweight and durable.
  • Prosthetic design also reflects developmental stages eg. Child with disarticulation may go form having stumpy (socket with peg base) in early years and progression to attachment of foot and then progression to a knee joint. The size and weight of components often dictate when a component may be added rather than simply gauging when a child is cognitively ready to use a new component eg. progression from extension prosthesis to inclusion of a knee joint.
  • Due to rapid growth, the prosthesis may include design features unlike adult populations eg. added sockets or thicknesses of sockets, more modular components to accommodate height growth; growth oriented suspension systems, etc.

Complications

  • As indicated in the ‘Immature Skeletal System’ section, the key difference in paediatrics with regard to post-operative complications is the development of terminal overgrowth. This is far more frequent in children than in adult populations.
  • Its recurrence can be as frequent as every two years until reaching skeletal maturity.

Follow Up

  • Paediatric limb deficiency requires far greater follow up than in adult populations due to ongoing growth and development.
  • For this reason, it is important to see children who are using prostheses at least once a year. Many children with upper limb deficiencies that don’t use prostheses, may access the clinic ever 2-3 years. Children who are undergoing growth spurts may require reviews 3-6monthly.

Resources

Day, H.J.B. The ISO/ISPO Classification of Congenital Limb Deficiency in Atlas of Limb Prosthetics. http://www.oandplibrary.org

References