Children’s Orthopaedics multiple-choice questions

Part 1 of the FRCS (Tr & Orth) is the written part of the exam and consists of two papers. The first paper is sat in the morning while the second paper takes place in the afternoon. The Joint Committee on Intercollegiate Examinations endeavours to provide a minimum of 30 minutes between each paper.

It is considered the easiest part of the exam to pass, the clinicals and vivas being the difficult hurdles. This can lead to a false sense of security and some candidates may not apply themselves in their reading preparation as much as needed. The other issue is that candidates are not expected to fail this section, and this may increase expectations and pressures on candidates. The UK In-Training exam acts as a dress rehearsal and should be completed yearly by orthopaedic trainees. Your score should improve yearly and ideally peak the year before you sit the real exam. From 2013, the pass mark for the Part 1 exam has been increased by the Examination Board. This was unpredicted and means that candidates have to ‘up’ their exam preparation to avoid falling at this hurdle.

Background

Although a rare condition (2:100 000), slipped upper femoral epiphysis (SUFE) is one of the most common types of paediatric and adolescent hip disorder. The incidence of SUFE varies with:

1. Sex: SUFE is more common in boys (75% of cases) with the peak incidence occurring at 12 to 15 years compared with 10 to 13 years in girls. Thus, boys tend to have their slip 2 years older than girls. SUFE is rarely reported after the age of 20 years [1].

2. Race [2]: SUFE is more common in those of African and Polynesian descent.

3. Laterality: SUFE is more common on the left side (as is developmental dysplasia of the hip (DDH)). The reason is unknown; it may be related to the sitting posture of right-handed children while writing. The incidence of bilaterality has been reported to be as high as 50%, although the generally accepted incidence is 20%. In children with bilateral involvement, 50–60% present with simultaneous SUFEs and those who present with a unilateral SUFE and subsequently develop a contralateral SUFE do so within 18 months. Younger patients and those with endocrine or metabolic abnormalities are at much higher risk of bilateral involvement.

4. Seasonal variations: this is debatable; some studies have suggested that SUFE is more common in June and July.

Aetiology

Although, the cause is poorly understood, it is believed that increased shear forces or a weak growth plate (the physis) in adolescence predisposes to SUFE. This results in the head of the femur staying in the acetabulum and the neck slipping forward and outward.

Non-accidental injury

Background

Ambrose Tardieu first reported non-accidental injury (NAI) in 1860, noting the correlation between cutaneous lesions, fractures, subdural haematomas and death [1]. Caffey again highlighted the association between long bone fractures and subdural haematomas in 1946 [2]. However, it was Henry Kempe who raised the profile of NAI in 1962 when he coined the term ‘battered-child syndrome’ [3]. He described the association between multiple fractures, subdural haematomas, failure to thrive, soft-tissue swelling or bruising and sudden unexplained death. He also highlighted the importance of situations in which the type or degree of injury did not correlate with the history. The US Child Abuse Prevention and Treatment Act (CAPTA) defines child abuse and neglect as:

Child abuse is more common than most would expect; it is estimated that 7% of children suffer serious physical abuse. Studies suggest that 25% of fatally abused children had been seen recently by a healthcare provider [4].

Since 1998, I have convened an annual core curriculum lecture course in paediatric orthopaedics at Alder Hey Children’s Hospital. Over the years, we have frequently been asked to recommend books that succinctly cover all of the necessary information and I now believe that we have found such a book in Postgraduate Paediatric Orthopaedics: The Candidate's Guide to the FRCS (Tr & Orth) Examination. As the title suggests, the text is targeted toward trainees sitting the FRCS (Tr & Orth) examination but the book would also be useful for those who seek to enhance or maintain their paediatric orthopaedic knowledge base, including practicing orthopaedic surgeons, GPs, paediatricians and specialist physiotherapists. The text is much more than lecture notes and covers all of the major subjects with sufficient information to keep the reader interested, while still delivering the required facts to an examination candidate as quickly as possible. I congratulate the editors and the authors for producing such as useful text.

Aetiology

The incidence of obstetric brachial plexus birth injury (OBPI) is around 1 per 1000 live births. Around 25% of patients are left with permanent disability without intervention. The shoulder is the most commonly affected joint and, owing to the subsequent imbalance of musculature, the abnormal deforming forces cause dysplasia of the glenohumeral joint. In the growing child, this presents with a changing pattern of pathology, which requires a multidisciplinary approach and a broad range of treatment modalities to optimize function.

A common cause is a traction injury to the brachial plexus during the later stages of vaginal delivery when the head is pulled away from the shoulder. The mechanism of injury is a forced lateral flexion of the cervical spine, resulting in injury initially to the upper cervical roots (C5–C7), causing an Erb’s palsy, and, in more severe cases, the entire brachial plexus (C5–T1). With this mechanism, isolated lower root injuries (C8–T1, Klumpke’s palsy) do not tend to occur in OBPI. Other rare causes are abnormal forces on the shoulder over the sacral promontory or abnormal forces in an abnormal uterus, such as a bicornuate or fibroid uterus.

Introduction

We can almost hear you sigh and exclaim, ‘Not another chapter on general FRCS (Tr & Orth) exam guidance!’ There are so many ‘candidate’s exam experiences’ out there for everybody to read and digest. What new spin can they add to the same old story?

It is still necessary to include this chapter, as it neatly sets the scene for the exam. Perhaps more importantly, the exam focus regularly changes and you definitely want to keep ahead with the latest developments.

Finally, the nature of the book means that it is necessary to consider how the paediatric section of the exam fits together within the wider FRCS (Tr & Orth) exam.

A lot of this general advice can be found elsewhere, as we alluded to, in the various candidate accounts floating round the internet. The problem is that most of these ‘candidate experiences’ are in a very similar vein and after reading the first two or three very little extra new material is then uncovered. While the general exam guidance advice in the general and viva-focused Postgraduate Orthopaedics books contains few surprises, both books cover the material to a greater depth and sophistication than elsewhere. Candidates may want to search out the relevant book chapters for this information.

Why another exam-related FRCS (Tr & Orth) book? Don’t we cover paediatrics in the chapters of the other Postgraduate Orthopaedics books?

1. We always felt the need for a more definitive guide to the paediatric component of the FRCS exam.

2. We were never entirely happy that the FRCS (Tr & Orth) paediatric syllabus was particularly well covered or developed in a number of orthopaedic books. Most lacked the specific subject focus that candidates needed to pass the FRCS (Tr & Orth) exam.

General orthopaedic books tended to scratch the surface of a difficult area of orthopaedics that needs to be learnt well for the exam. Specialized books on paediatrics meant you could lose all focus of the subject’s relevance and end up not extracting the relevant or specific detail required to pass the exam. Moreover, you could find yourself spending a lot of unnecessary time and effort drowning in these specialized textbooks and not have enough time left to read the basic science, trauma or hands sections.

The development of the upper limb begins during the fourth week of life in utero, when a limb bud, consisting of undifferentiated mesenchymal cells encased in ectoderm, develops. By 9 weeks, the bud has developed into an arm and hand with identifiable digits, and by 12 weeks the digits have differentiated.

Growth and differentiation are under the control of signal regions at the tip of the developing limb with complicated interactions and feedback systems (Figure 9.1). Induction of mesenchymal cells in the ‘progress zone’ at the tip of the developing limb occurs under the influence of specific zones. The apical epidermal ridge (AER) is the director of growth in the proximodistal axis (excision of the AER results in a limb stump only, while transplantation may result in a duplicate limb). Differentiation in the radioulnar axis is under the control of the zone of polarizing activity (ZPA) (transplantation of the ZPA can give rise to a ‘mirror hand’). Differentiation in the volardorsal axis is under the control of the dorsal ectoderm (excision and rotation of this zone causes dorsal muscles to form ventrally). Thus, there is a complicated interaction between genes and the proteins they encode, which induces the cells of the AER, ZPA and dorsal zone that drive limb developing and patterning. Anomalies in these processes result in anomalies in limb development, and may be the result of genetic mutation, interruption of a pathway at molecular level or gross insult. The aetiology of such insults can be environmental, e.g. radiation, infection or chemical (including drugs), or hereditary, as part of a syndrome.

Bow leg and knock knees

Bow leg (Figure 4.1) and knock knees are common referrals to children’s orthopaedic clinics. Most are physiological; however, pathological causes must be excluded (Table 4.1).

The leg alignment in the coronal plane (varus and valgus) undergoes a unique pattern of changes from birth until adulthood, as described by Salenius and Vankka [1]. Most newborn babies have an average knee varus of 10°–15°. This begins to be corrected during the second year of life, reaching about 10° of valgus at around 4 years of age. The valgus alignment then gradually decreases, reaching the adult value (5° of valgus) around 8 years of age (see Figure 4.2). The standard deviation (SD) is 8° (more in the boys, 10°, and less in the girls, 7°).

Children with physiological genu varum and internal tibial torsion typically come to medical attention after the standing age (between 12 and 24 months), usually because of parental concern regarding the appearance of the legs, and these children have no other significant findings on clinical examination.

Recognizing ‘normal’

In any paediatric orthopaedic examination, it is vital that progress in achieving developmental milestones is evaluated. Familiarity with the normal will alert the examiner to the abnormal.

Mobility and ambulation

Approximately 90% of normally developing infants are able to:

• Roll themselves by 6 months,

• Sit without support by 8 months,

• Pull themselves up to stand by 10 months,

• Walk by 15 months,

• Hop on one foot by 4 years.

Note, however, that 10% of children will normally achieve these milestones later, but failure to walk by 2 years of age should be investigated.

A normal toddler gait is wide-based and stiff-kneed. A mature ‘adult’ gait, with its characteristic reciprocal arm swing, develops from 3.5 years onward.

Upper-limb development

• Transfer of objects between hands: normally from 8 months,

• Opposition and release of objects: from 1 year,

• Proper grasp and release: 18 months,

• Finger-grip to hold a crayon: 2 years,

• Writing: from 4 to 5 years.

The following red flags should prompt further evaluation:

• Not rolling over by 6 months,

• Not sitting by 8 months,

• Handedness before 12 months,

• No words by 14 months,

• Not walking by 18 months.