Achilles Tendon Involvement in Pediatric Conditions

25 Achilles Tendon Involvement in Pediatric Conditions

Ramanathan Natarajan and W.J. Ribbans

Introduction Traumatic Conditions A common painful condition in children causing The Achilles tendon is involved in a variety of heel pain is the so-called calcaneal apophysitis pediatric conditions. Intrinsic tendon abnormali- described by Sever in 1918, associated with ties such as tendinopathy and rupture are rare in overuse. Insertional and noninsertional Achilles the pediatric population, but the tendon is often tendon disorders are not infrequently encoun- secondarily involved in some common pediatric tered in adolescents, often from overuse.3 conditions that can be categorized under the fol- lowing headings: • Congenital Neurological Conditions • Developmental Achilles tendon shortening or weakness is a • Traumatic feature of many neurological conditions affecting • Neurological the central or peripheral nervous system (cerebral palsy, poliomyelitis, spina biﬁ da, and hereditary Congenital Conditions neuropathies) and muscles (muscular dystrophy). Achilles tendon spasticity, weakness, or contrac- Contracture of the Achilles tendon is a constant ture in these conditions leads to gait abnormali- feature of congenital conditions such as clubfoot ties. Understanding the role played by the triceps and congenital vertical talus. The tendon can fully surae in the unique coupling of ankle and knee regenerate after complete tenotomies in infancy. motion is essential in the management of gait This unique property is utilized in the currently abnormalities from tightness of the gastro-soleus– popular nonoperative management programs for Achilles tendon complex. congenital clubfoot.1 Lengthening of Tendo Achillis Developmental Conditions As tightness of the Achilles tendon features in Achilles tendon shortening is also a feature of many pediatric conditions, its lengthening is com- developmental conditions such as ﬂ atfoot, and it monly undertaken. Excessive lengthening of the is still unclear whether the tightness of Achilles tendon and the resulting weakness of the gastro- tendon in this condition is a primary or secondary soleus–Achilles tendon complex may lead to dete- abnormality. Another developmental condition rioration of gait, particularly in neurological associated with dynamic or static tightness of the conditions. Understanding of the complex rela- Achilles tendon leading to an abnormal gait is tionship between hip, knee, and ankle joint idiopathic toe walking (ITW).2 kinematics in spastic neurological conditions is

236 25. Achilles Tendon Involvement in Pediatric Conditions 237 necessary to avoid the pitfall of surgically weaken- malities affecting the leg-foot unit in an otherwise ing the Achilles tendon by lengthening. Three normal child. relatively large muscles power the tendon. The Abnormal shortening of the Achilles tendon in two gastrocnemei are bi-articular muscles span- clubfoot is secondary to the intrinsic foot defor- ning the knee and ankle joints. Selective gastroc- mity. The abnormally shaped talus in clubfoot nemius aponeurotic release may be preferable to results in medial talonavicular subluxation9,10 and lengthening of the whole tendon to avoid perma- internal rotation of the calcaneum underneath the nent weakness of the gastro-soleus–Achilles deformed talus. Calcaneal rotation manifests as tendon complex. Permanent weakness of this heel varus and equinus. The soft tissue contrac- musculotendinous complex will cause an abnor- ture of tendons and ligaments, including the mal gait with weak push-off, and is not uncom- Achilles tendon, maintains this deformity. mon after open Achilles tendon lengthening in Surgical release or lengthening of the Achilles congenital clubfoot.4 tendon is often necessary to correct the equinus deformity in clubfoot. The currently popular manipulative treatment methods also employ Congenital Disorders with Achilles Achilles tendon tenotomy for correction of the equinus deformity. Serial weekly casting to correct Tendon Abnormalities all components of the deformity except equinus followed by Achilles tendon tenotomy to achieve Talipes Calcaneovalgus 15° of dorsifl exion at fi nal casting is widely prac- This benign foot positioning abnormality of the ticed (Fig. 25.1). This approach is popularly 11 A 30-year newborn is relatively common (1 in 1,000 live referred to as the “Ponseti method.” follow-up of 71 patients treated12 shows retention births),5 caused by hyper-dorsifl exion of the foot against a tight uterus. Silent hip dysplasia may be of excellent gastro-soleus function in over 78% of associated with this condition6 and needs to be feet, a signifi cant improvement over the results of ruled out by ultrasound examination of the hip. surgically managed clubfeet. Coupled with the The structure of the foot is normal, and the defor- remarkable lack of stiffness in the feet managed mity resolves spontaneously. Passive stretching is by using the Ponseti method, this has led to a great always successful but serial casting may be neces- resurgence of interest in manipulative treatment sary occasionally. The deformity usually resolves of clubfoot. Gait abnormalities secondary to weakness of lengthened Achilles tendon is almost uni- by the sixth month of life and residual Achilles 4,13 tendon sequelae are seldom seen. versal in clubfoot treated by open surgery. Insuffi ciency of the gastro-soleus secondary to Some investigators believe that talipes calcane- open surgical release of clubfoot is common, and ovalgus and symptomatic hypermobile pes planus notoriously diffi cult to treat. Attention to detail seen in an older child may be etiologically linked during the primary procedure may prevent over- and recommend active treatment of the more lengthening. Coronal plane Z-plasty to produce severe deformity.7,8 two wide strips of tendon for correct tensioning of the lengthened tendon is important. Vigorous Congenital Clubfoot postoperative manipulation under anesthetic (Congenital Talipes Equinovarus) during cast change should be avoided to prevent tendon rupture.14 Early diagnosis of gastro-soleus Congenital clubfoot causes a fi xed ankle and foot weakness can be made by gait observation and deformity often identifi ed by the 20-week ante- radiographical appearance of the calcaneus. Man- natal scan. The incidence of the idiopathic condi- agement of symptomatic gastro-soleus weakness tion is 1 to 2 in 1,000 live births. Secondary talipes involves tendon transfer. Peroneus brevis, fl exor equinovarus deformity is seen in a variety of syn- hallucis longus, and tibialis posterior tendons can dromes, arthrogryposis and spinal dysraphism, be transferred to the calcaneus using tendon-bone secondary to muscle imbalance. The idiopathic fi xation where possible. Tibialis anterior transfer type results in localized musculoskeletal abnor- is best avoided to prevent disabling foot drop 238 R. Natarajan and W.J. Ribbans

FIGURE 25.1. Tenotomy of Achilles tendon in a 3-month- old infant to correct clubfoot deformity by Ponseti method. Complete tenotomy of the Achilles tendon in an infant does not cause long-term weakness. (A) Appear- ance of the foot before tenotomy. Note full correction of forefoot deformities. (B) Full correction of equinus after tenotomy. (C) Correction maintained at 6 months of age.

C 25. Achilles Tendon Involvement in Pediatric Conditions 239 postoperatively, but has been used with some bone adjacent to the calcaneal apophysis.3 Achil- success in clubfoot.15 In older children, calcaneal les tendon stretches have been traditionally advo- posterior displacement osteotomy may be neces- cated for this self-limiting condition, although sary to increase the lever arm of the transferred there is no evidence of pathological shortening of tendons. Multiple combined tendon transfers to the Achilles tendon. the calcaneum may not restore normal plantarfl exion strength but several patients have developed toe-up ability, especially when the Overuse Injuries of the Achilles surgery was performed prior to age 6.14 Tendon in Children Insertional and noninsertional Achilles tendon Congenital Vertical Talus (CVT) problems have been reported in adolescent athletes. Achilles tendon rupture from athletic activi- Congenital vertical talus or congenital convex pes ties is extremely rare under the age of 20.19 Clinical valgus is a rigid deformity of the foot with a examination may identify predisposing factors rocker-bottom appearance. CVT is a teratological such as foot pronation in stance, plantar fascia dorsolateral dislocation of the talocalcaneo-navic- and Achilles tendon tightness, cavus foot, and ular joint.16 This condition is rare and often asso- obesity. Faulty running shoes and technique may ciated with other congenital limb, visceral, and also contribute to the symptoms, but a common neuraxis abnormalities. This condition can be dif- underlying cause is excessive physical activity.19 ferentiated from severe fl atfoot by rigidity of the Ultrasonography20 and magnetic resonance foot and resistance to passive restoration of the imaging are helpful in evaluation of these overuse longitudinal arch in CVT. The lateral radiograph injuries. The pathology of Achilles tendon pain in in CVT shows the talus in plantarfl exion almost young athletes includes tendon sheath infl amma- parallel to the distal tibia. In forced plantarfl ex- tion (paratendinopathy), occasional tendinopathy ion, the navicular fails to reduce on the talus and of the main body of the Achilles tendon, and ret- stays dorsal to the talar head.17 rocalcaneal bursitis. In adolescents with intracta- The Achilles tendon is invariably contracted, ble Achilles tendinopathy, the possibility of maintaining the calcaneum in equinus. Surgical juvenile chronic arthritis should be entertained single-stage correction is the mainstay of treat- and appropriate investigations performed. Modi- ment and passive stretching and casting can be fi ed rest, anti-infl ammatory medication, and very used to loosen soft tissues before surgery. Surgery short immobilization of the foot and ankle in a involves dorsal capsulotomy and relocation of the below-knee cast are successful in relieving pain in talonavicular joint, dorsal extensors and peroneal the majority of cases. A talar-neutral orthosis to tendon lengthening if indicated, and lengthening prevent foot pronation and regular Achilles of the tendo Achillis. The relocated talonavicular tendon stretching are generally successful in alle- joint is secured with a wire and held for 4 weeks. viating the symptoms. Surgical management for The results of one-stage surgery for CVT are gener- insertional and noninsertional Achilles tendon ally good, but residual forefoot abduction, midfoot disorders is seldom necessary in this age group. sag, and joint stiffness are to be expected.18

Post-traumatic Achilles Tendon Developmental Foot Disorders with Disorders in Children Achilles Tendon Tightness Sever’s Lesion Hypermobile Flat Foot with Short Tendo Achillis This is a common cause of heel pain in athletic older children and adolescents between the ages In a study of 3,600 Canadian army recruits, Harris of 8 and 12. The etiology is likely to be post-trau- and Beath21 found that the presence or absence of matic due to a micro-injury of the metaphyseal longitudinal foot arch did not correlate with dis- 240 R. Natarajan and W.J. Ribbans ability. They also described a small group of sub- Lengthening of the Achilles tendon should be jects with symptomatic fl at feet in whom there was avoided to prevent weakness. associated Achilles tendon contracture. They coined the phrase “hypermobile fl atfoot with Idiopathic Toe Walking (ITW) short tendo Achillis” to describe this condition.21 Up to 25% of subjects with fl at feet may have an Idiopathic toe walking should be considered a associated Achilles tendon contracture. possible diagnosis in any child who toe walks after Older children with hypermobile fl atfoot asso- the age of two. ITW is a diagnosis of exclusion. ciated with Achilles tendon contracture tend to Neurological conditions that cause toe walking, have callosities over the plantar medial promi- such as cerebral palsy, muscular dystrophy, nence of the talar head, and may not tolerate rigid spinal cord abnormalities, and poliomyelitis, inserts. The heel valgus in these children may be should be excluded. A comprehensive develop- considered a secondary compensation to accom- mental history and clinical examination should modate the tight Achilles tendon, although it is establish the diagnosis, although additional equally possible that the Achilles tendon contrac- gait analysis and EMG studies may occasionally ture is secondary to long-standing heel valgus. be necessary to differentiate mild cerebral palsy Examination of feet with this condition should from ITW.25 reveal normal or excessive painless subtalar joint Children with ITW typically walk on their toes, mobility, restoration of the longitudinal arch but can put their foot fl at on request or when when non-weight-bearing, and Achilles tendon concentrating on their gait. A positive family tightness. Achilles tendon tightness should be history is found in 35–71% of cases.26,27 Develop- assessed with the heel locked in inversion. mental delays relating to speech, language, gross Management should initially be directed to- or fi ne motor skills, and visual-motor develop- ward passive stretching of the Achilles tendon. ment have been found in a signifi cant proportion Older children can be given home stretching of children with ITW. Some investigators have exercises.22 Rigid inserts may not be tolerated suggested that ITW should be viewed as a marker due to pressure against the unyielding medial for developmental problems and recommend that arch eminence of the insert.23 Soft inserts or children with ITW should be referred for a devel- running shoes and regular stretching should opmental assessment.2 reduce the symptoms in most children and ado- The etiology of ITW is not fully understood. lescents with this condition. Surgery should be the The condition was originally described as “con- last resort in a few selected patients. Persistent genital short tendo Achillis,” and this may well be pain over the prominent talar head and medial the case in some patients.28 EMG studies on ITW arch pain on activity despite prolonged nonopera- patients have shown changes similar to those seen tive treatment may constitute an indication for in cerebral palsy patients with equinus deformity. surgery. Biopsy specimens of calf muscles in operated Several surgical procedures have been described. patients have shown features suggestive of a neu- Insertion of expansible sinus tarsi implants to ropathic process, indicating a possible neurogenic limit subtalar joint mobility is advocated for fl ex- basis for this condition.29 ible fl atfoot, particularly in the podiatry literature, The natural history of untreated ITW is not but there are no long-term outcome studies.22 fully understood. In one study, 14 children with Evan’s osteotomy of the anterior process of the ITW were followed up for 7 to 21 years, and 11 of calcaneum to restore the physiological talocalca- these were subjected to clinical examination and neal and talonavicular relationship has withstood their gait videotaped. Three showed some evi- the test of time.24 Additional surgery on the medial dence of toe walking when unobtrusively observed, aspect to reef the spring ligament and shorten the but the others walked with a heel strike. The tendon of tibialis posterior may be necessary in authors concluded that toe walking eventually conjunction with Evan’s osteotomy.23 A gastroc- resolved spontaneously in most children, and rec- nemius slide should be an integral part of any ommended that surgical treatment of ITW should surgery when Achilles tendon tightness is marked. be reserved for the few cases with a fi xed ankle 25. Achilles Tendon Involvement in Pediatric Conditions 241 joint contracture.30 Serial casting has been advo- lesion, the child may suffer from hemiplegic, cated, but appears to be ineffective on its own.31 spastic diplegic, or total-body-involvement cere- To stretch the gastro-soleus–Achilles tendon bral palsy. This chapter focuses on ankle and foot complex, the foot needs to be supinated and dor- abnormalities in cerebral palsy, and refers to the sifl exed, and casted in that position, which is not spastic rather than dystonic type of cerebral amenable to walking.32 palsy. Botulinum toxin A (BTx-A) is being increas- The management of movement disorders in ingly used to treat ITW but the long-term outcome cerebral palsy should involve multiple disciplines of this intervention is not known. BTx-A has been including physiotherapy, pediatric neurology, shown to signifi cantly improve ankle kinematics orthotics, occupational therapy, and gait analysis and normalize foot-strike pattern in ITW patients. in addition to the orthopedic surgeon. Detailed This improvement appears to be maintained at 12 clinical examination to determine strength, selec- months after injection of BTx-A.33 tive control and tone of muscles, deformity of Surgery has been advocated for ITW in the joints, torsion of bones, and evaluation of balance form of closed lengthening followed by a cast. and equilibrium is essential. In a walking child, This procedure appears to produce uniformly gait analysis is an essential tool to make recom- good results.31,32 There is a risk of overlengthening mendations for management.34 the tendon, which can be minimized by undertak- ing percutaneous lengthening. Role of Ankle and Foot in Gait 35 Human gait consists of a stance and swing phase. Achilles Tendon in Childhood The action of the foot in the stance or support Neurological Conditions phase is described in terms of three rockers (Fig. 25.2).36 During the fi rst rocker, the heel makes Cerebral Palsy ground contact, and the ground reaction force (GRF) with its fulcrum at the heel produces a Movement disorders in cerebral palsy result from plantarfl exion moment. This force moment is ante-, peri- or post-natal insult to the immature restrained by the eccentric contraction of anterior brain. Although the primary neurological injury tibial muscles that dampen the GRF and plays a is nonprogressive, secondary musculoskeletal shock-absorbing role. pathology deteriorates in untreated children. The GRF passes anterior to the ankle joint Depending on the level and extent of the brain during the second rocker in the mid-stance. This

1st 2nd 3rd

FIGURE 25.2. The three foot rockers in stance phase. The dorsiflex- tarflexors contract concentrically to achieve a push-off. (Illustration ors and plantarflexors contract eccentrically (lengthening contrac- taken from Gage, 1991; see References 34, 35, 39. Reprinted with tion) in the first and second rockers and are called deceleration permission from Mac Keith Press.) rockers. The third rocker is an acceleration rocker where plan- 242 R. Natarajan and W.J. Ribbans produces a dorsifl exion moment with its fulcrum across both ankle and knee joints, but isolated now at the ankle joint level. This moment is muscle lengthening of the gastrocnemius will resisted by the eccentric contraction of triceps achieve selective weakening without affecting the surae. This restraint comes chiefl y from the slow- soleus, which, as discussed above, is important for twitch soleus muscle with later assistance by the stance phase knee/ankle stability. Further, con- gastrocnemius and long toe fl exors. The tibia is tracted triceps surae dealt with by tendo Achillis held back by the contraction of the soleus, thereby lengthening may shorten with bone growth, as a keeping the GRF in front of the knee joint. By lengthened muscle is not subjected to stretch with remaining anterior to the knee, the GRF main- bone growth. Muscle stretch due to bone growth tains limb stability, as the knee is inherently stable has been shown to be an impetus for muscle in full extension even without quadriceps contrac- growth.40 tion. This extension moment on the knee gener- ated by the GRF to achieve knee stability in Hemiplegia mid-stance even without muscle contraction is called the plantarfl exion/knee extension couple In a hemiplegic child, treatment has traditionally (Fig. 25.3). focused on the ankle to address the commonly Toward the end of the mid-stance phase, the encountered equinus deformity in this condition. combined action of plantarfl exors raises the heel, Gait analysis in hemiplegics has shown a spec- and the fulcrum for this action moves to the meta- trum of limb involvement of increasing severity. tarsal heads. This is the third rocker, and the Based on gait analysis, four basic patterns of action of the plantarfl exors now switches from motor disorders have been identifi ed in hemiple- eccentric or lengthening contraction to concentric gia: types I to IV.41 Dynamic or static equinus is or shortening contraction, thereby achieving the seen due to plantarfl exor overactivity in types I push-off and forward acceleration. and II, without signifi cant involvement of the In cerebral palsy, the fi rst rocker can be absent knee and hip. Inadequate swing phase knee fl exion due to dynamic or static plantarfl exion at the ter- is seen in type III due to co-spasticity of the ham- minal swing phase. In spastic diplegia, initial toe strings and rectus femoris. Type IV hemiplegics contact in stance may occur even without a static have additional involvement of the hip fl exors and or dynamic ankle plantarfl exion due to knee adductors. It is therefore important when manag- fl exion deformity.37 Excessive lengthening of the ing a hemiplegic gait to identify coexisting proxi- Achilles tendon without addressing the knee and mal limb involvement and address all issues hip problems may lead to a dramatic deteriora- simultaneously through orthotics or surgery. tion of gait due to weakness of plantarfl exion causing migration of GRF posterior to the knee, Spastic Diplegia and Total Body Involvement resulting in a crouch gait. Children with cerebral palsy possessing walking potential should undergo In spastic diplegia, the lower limbs are predomi- gait analysis and electromyographic studies to nantly involved with relative upper limb sparing. precisely identify the abnormal kinematics and Ankle involvement is invariably associated with kinetics of their gait before surgery. Surgical pro- knee, hip, and pelvic abnormalities. Gait analysis cedures on triceps surae in cerebral palsy should is essential before surgery to identify the abnor- be undertaken as part of a multilevel surgery to mal kinematics and kinetics at each level. In diple- address pelvis, hip, and knee problems identifi ed gics, initial toe contact at the fi rst rocker can be by gait analysis.38 secondary to knee fl exion deformity, and patients The triceps surae, with other bi-articular may excessively dorsifl ex their ankle to maintain muscles such as psoas, hamstrings, and rectus a foot fl at gait. Since the soleus spans only the femoris, are mainly involved in cerebral palsy, ankle joint, it is not shortened, but may in fact be probably because the strength and timing of these long. Overlengthening of the Achilles tendon in muscles have to be far more precise than mono- such patients will worsen the knee and hip fl exion, articular muscles.39 Lengthening of the Achilles leading to a crouch gait (Fig. 25.4). Secondary tendon as a whole will weaken the triceps surae tightness of the gastrocnemius occurs when the 25. Achilles Tendon Involvement in Pediatric Conditions 243

FIGURE 25.3. Plantarflexion/knee extension couple. The contraction of soleus during the second rocker restrains the tibia and keeps the knee joint behind the ground reaction force (GRF). The knee joint is inherently stable in extension even without the contraction of quadriceps. (Illustration taken from Gage, 1991; see References 34, 35, 39. Reprinted with permission from Mac Keith Press.)

Soleus

PF / KE COUPLE

GRF 244 R. Natarajan and W.J. Ribbans

Toe walker Foot flat

Post-Op Calcaneal Gait

FIGURE 25.4. In a spastic diplegic child with crouched knee and leading to a calcaneus gait. (Illustration taken from Herring JA, ed., toe-to-toe gait, the ankle is actually in a neutral position. Excessive Tachdjian’s Pediatric Orthopaedics, Vol. 2. Philadelphia: W.B. Saun- lengthening of Achilles tendon causes excessive ankle dorsiflexion, ders Company, 2002. Reprinted with permission from Elsevier.)

knee is surgically straightened by hamstrings Achilles Tendon Lengthening in Cerebral Palsy lengthening: this will necessitate gastrocnemius Isolated Achilles tendon surgery and multilevel release. Again, surgery should address hip, knee, surgery in cerebral palsy is best delayed until chil- ankle, and foot problems simultaneously. dren are at least 8 year old: by that time, gait is 45 Botulinum Toxin A (BTx-A) in Cerebral Palsy well established. Equinus deformity in cerebral palsy can be corrected by selective gastrocnemius Botulinum toxin A (BTx-A) is widely used to recession or by Achilles tendon lengthening. The control spasticity in cerebral palsy.42 BTx-A acts Silverskiold test differentiates tightness of the by blocking neurotransmission to muscles, reduc- Achilles tendon from isolated tightness of gas- ing spasticity, and improving muscle balance. trocnemius component alone. If full correction of BTx-A injections in the calf muscle can signifi - the ankle equinus is achieved by fl exing the knee, cantly delay surgery in children with cerebral the gastrocnemius is involved, and a selective palsy, thereby reducing the incidence of repeat release is indicated. The Silverskiold test per- surgery.43 Recurrence of Achilles tendon contrac- formed under anesthetic can be used to determine ture and need for repeat surgery is higher in chil- the appropriate release.46 Gastrocnemius reces- dren with hemiplegia and diplegia undergoing sion may be performed using a variety of tech- open Achilles tendon surgery under the age of 6 niques, and the techniques of Vulpius, Strayer, years.44 BTx-A administration to the calf muscles and Baker are commonly used (Fig. 25.5).47 The increases the compliance of orthotics wear in chil- gastrocnemius aponeurosis is exposed in the mid- dren with cerebral palsy.45 Multilevel BTx-A injec- calf through a longitudinal incision, and released tions after gait analysis reduces the frequency of transversely or in a chevron fashion. The underly- surgery in cerebral palsy up to the age of nine in ing soleal aponeurosis is not disturbed, but the comparison with children not injected with soleal septum is released. Care should be taken to BTx-A.45 avoid the sural communicating nerve in the vicin- 25. Achilles Tendon Involvement in Pediatric Conditions 245 ity of the incision. Gastrocnemius recession pre- Achilles tendon lengthening can be performed serves the power of the Achilles tendon during using open or percutaneous techniques. Open Z- push-off,48 and carries no risk of overcorrection lengthening should be undertaken with great and calcaneus deformity. A greater recurrence caution in walking children, and sutured under of equinus has been reported after gastrocne- appropriate tension to prevent overlengthening mius recession compared with Achilles tendon and calcaneus postoperatively. Closed techniques lengthening.49 involve two or three hemisections of the tendon proximally and distally, followed by manual stretching of the tendon with heel locked in varus. Neutral ankle position is achieved with the knee in extension and a cast applied. A popular technique is the Hoke method, where the Achilles tendon is released proximally and distally by medial hemisections and a lateral hemisection performed in the middle (Fig. 25.6).50 A rare complication of closed percutaneous release is complete severance of the tendon. If complete tendon severance is suspected, the calf squeeze test should be performed.51 If there is no passive plan- Gastrocnemius m. tarfl exion on calf squeeze, the tendon may be severed, and an open repair is indicated. This complication is extremely rare after percutaneous release.

Tendo Achillis in Spina Bifida Foot deformity is found in 75–90% of patients with spina bifi da,52 depending on the level of the lesion. Lower lumbar and sacral lesions result in Soleus m. calcaneus deformity, while in upper lumbar and thoracic lesions equinus is more common. Equinus, calcaneus, equinovarus, vertical talus, and valgus ankle deformities are all seen in this condition.3 The loss of sensation makes children with this condition prone to pressure sores, particularly when casting is used. For the same reason, fractures of the lower tibia and fi bula secondary to manipulation of foot deformities may be missed. Although manipulation of foot deformities is recommended as the fi rst line of management in spina bifi da, it should be gentle to avoid fractures.

Equinus Deformity FIGURE 25.5. Gastrocnemius aponeurotic release by Vulpius method. A single-level transverse division of the gastrocnemius Pure equinus deformities are common, and are 52,53 aponeurosis is sufficient. The underlying soleus and its aponeurosis mostly a positional deformity. Equinus defor- are left intact. (Illustration taken from Herring JA, ed., Tachdjian’s mity may in some patients be secondary to poste- Pediatric Orthopaedics, Vol. 2. Philadelphia: W.B. Saunders Com- rior transfer of the tendon of tibialis anterior for pany, 2002. Reprinted with permission from Elsevier.) calcaneus deformity. Passive manipulation is 246 R. Natarajan and W.J. Ribbans

Achilles tendon

Cuts in tendon

FIGURE 25.6. Hoke method of Achilles tendon lengthening. This lengthening and calcaneus. (Illustration taken from Bleck, 1987; method can be performed closed or open. The limb should be see References 47, 50. Reprinted with permission from Mac Keith dorsiflexed to achieve neutral position and no more to avoid over- Press.) effective in the early stages, but care should be mity is essential as delay in surgery increases the exercised to avoid distal tibial fractures secondary prevalence of calcaneal ulcers signifi cantly.55 to manipulation, particularly in infancy. Often Surgery consists of anterior capsular release and surgery is needed, and this should be timed to posterior transfer of the tibialis anterior to the coincide with lower limb bracing for standing and calcaneus with the ankle in neutral position. This ambulation. Closed or open Achilles tendon transfer can never substitute for the power of the lengthening is performed, and a well padded gastro-soleus–Achilles tendon complex, and below-knee cast applied. Long-term bracing is hence long-term bracing is essential. The foot essential to prevent recurrence. should not be casted in equinus postoperatively, as this may lead to an equinus deformity. Further, Calcaneus Deformity passive manipulation to achieve a neutral position may cause a pathological distal tibial Calcaneus deformity (Fig. 25.7) is often secondary fracture. to muscle imbalance in lower lumbar lesions due 54,55 to unopposed tibialis anterior action. Calca- Equinovarus Deformity neus deformity may also occur due to positioning in utero or post-natally. Positional deformities Secondary clubfoot deformity is often associated can be gently manipulated, but those due to with spina bifi da irrespective of the level of lesion.56 muscle imbalance often need surgical correction. Clubfoot deformity in this condition is always Calcaneus deformity in spina bifi da is diffi cult to severe and rigid, and is described as teratological. control with orthotics. Calcaneus deformity pre- Management is similar to the idiopathic type, but disposes to persistent, diffi cult-to-treat heel ulcers, extensive soft tissue and bony surgery is required which may lead to calcaneal osteomyelitis. For more frequently. Initial management should be this reason, early correction of calcaneus defor- gentle serial manipulations and well-padded casts. 25. Achilles Tendon Involvement in Pediatric Conditions 247

FIGURE 25.7. Calcaneus foot in spina bifida. Note the shortened tibialis anterior tendon.

These feet are insensate, and prone to pressure Ankle Valgus Deformity sores within the plaster casts. Posteromedial and Valgus deformity of the ankle is common in lateral soft tissue releases for correction of this ambulatory patients with spina bifi da, and may teratological deformity needs to be radical, and arise at the level of the ankle or hindfoot at the talectomy may be necessary for full deformity subtalar joint. A standing ankle anteroposterior correction.57 Unless function of the lower extrem- radiograph is necessary to identify the site of ity is well preserved, as in sacral or very low valgus deformity.60 Distal tibial osteotomy, distal lumbar lesions, tendon resections rather than medial tibial hemi-epiphysiodesis, or tendo lengthening or transfer are preferred to correct Achills–fi bular tenodesis can be used to treat deformities. Talectomy or triple arthrodesis may ankle valgus deformity depending on the age of sometimes be required to manage recurrent the patients, extent of the deformity, and the equinovarus deformity in spina bifi da patients, effectiveness of orthotics. but weight-bearing forces are not evenly distrib- Mild to moderate ankle valgus deformity in a uted after either of these procedures, leading to young child is amenable to Achilles tendon–fi bular neurotrophic ulcers.58,59 Surgical correction of tenodesis. A portion of the Achilles tendon, still clubfoot in this condition should be delayed until attached distally, is transferred laterally and the child is neurodevelopmentally ready for sutured to the fi bula above its distal physis. With orthotics and ambulation. weight bearing and ankle dorsifl exion, the Congenital Vertical Talus fi bula is pulled distally by the tenodesis, gradually correcting the deformity. The treatment is based This deformity is much less common in spina on the concept that distal fi bular growth is defi - bifi da than equinus, calcaneus, and equinovarus cient in spina bifi da from paralysis of the deformities.53 The rigid planovalgus foot makes muscles in the lateral compartment. Improve- manipulation diffi cult, and orthotics are usually ment in talar tilt and relative fi bular length was unsuccessful. One-stage surgery is necessary, fol- noted in most children managed by this method, lowed by prolonged splintage in orthotics. Achil- with some improvement in the orientation of the les tendon tenotomy is an integral part of this hindfoot. External tibial torsion remained procedure to correct the equinus. unaffected.60 248 R. Natarajan and W.J. Ribbans

Paralysis of Triceps Surae Muscle age. Other forms of muscular dystrophy are much in Poliomyelitis less common. Both DMD and BMD are X-linked recessive genes affecting only boys. The life expec- Flaccid lower motor neuron paralysis of triceps tancy in BMD is signifi cantly better than in DMD, surae is very disabling. The patient lacks push-off, and patients with BMD may retain independent and walks with a calcaneus limp. The lack of push- ambulation into early adulthood. off during the third foot rocker leads to an upward The earliest clinical manifestation of DMD may displacement of the anterior end of the calcaneum be ankle equinus, causing children to toe walk and head of talus. There is increase in the range (Fig. 25.8). Muscular dystrophy should be consid- of dorsifl exion and the normal posterior heel ered in any young boy presenting with toe walking. prominence disappears. Compensation by other The gastrocnemius muscle appears hypertrophic plantarfl exors such as tibialis posterior, long toe due to fi bro-fatty replacement of muscle fi bers: fl exors, and the peronei result in equinus of the this appearance is termed pseudohypertrophy. forefoot and eventually a calcaneo-cavus defor- Examination reveals proximal muscle weak- mity. Contracture of the short toe fl exors and ness. The child stands on his toes with his knees plantar fascia increases the cavus deformity. in hyperextension, locking the posterior capsule, When the triceps surae is completely paralyzed, thus achieving stability despite weak quadriceps. all available posterior muscles should be trans- Hip extensor weakness leads to anterior pelvic tilt ferred to the calcaneum. The peronei, tibialis posterior, and fl exor hallucis longus should be transferred posteriorly. In older children with fi xed deformity, a triple arthrodesis is necessary in addition to tendon transfer. The os calcis may need to be shifted posteriorly and the bony deformity corrected at arthrodesis. In younger children, if tendon transfers restore suffi cient plantarfl exion strength, the calcaneus deformity may correct spontaneously by remodeling. The tibialis anterior may need lateralization to cen- tralize it over the dorsum to prevent a dorsal bunion. When all plantarfl exors are paralyzed, the tendon of tibialis anterior is transferred to the calcaneum, and the foot braced until skeletal maturity. An additional extra-articular subtalar arthrodesis may be necessary in younger children to achieve hindfoot stability after tendon transfer. A triple arthrodesis will be necessary in an adolescent.61 When no motors are available to substitute for triceps surae, consideration should be given to ankle arthrodesis, providing there is adequate knee stability and muscle control.

Muscular Dystrophies Duchenne muscular dystrophy (DMD) is the most common form of muscular dystrophy, occurring in 1 in 3,500 boys. DMD usually manifests before FIGURE 25.8. This 4-year-old child with Becker muscular dystro- the age of 3. Becker’s muscular dystrophy (BMD) phy was referred for toe walking. Note the pseudo-hypertrophy of is less common, with disease onset at 7 years of calf muscles. 25. Achilles Tendon Involvement in Pediatric Conditions 249 with lumbar hyperlordosis during gait. The hips 5. Wynne-Davies R. Familial studies of the cause of are stable because of the ground reaction force congenital clubfoot-talipes equinovarus, talipes vector falling posterior to the hip.62 When asked calcaneovalgus and metatarsus varus. J Bone Joint to stand from a sitting position without assistance, Surg 1964; 46-B:445. the child will “walk” his hands up the lower limbs 6. Herring JA. Disorders of the foot. In: Herring JA, ed., Tachdjian’s Pediatric Orthopaedics. 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