Arthrogryposis is a term applied to a group of uncommon disorders that affect children and are associated with multiple joint contractures and dislocations. Owing to the heterogeneous nature of these relatively rare conditions and wide variations in recommended and applied treatments, there is only level IV and V evidence for the surgical management of the deformities associated with these conditions.
In the absence of strong levels of evidence, clinical approaches to these complex conditions may default to application of principles of management derived from the management of isolated musculoskeletal deformities. However, children with arthrogrypotic conditions can have multiple severe deformities, unique medical conditions, unique rehabilitative challenges, and widely varying access to resources that impact the outcomes of treatment. In addition, little information exists that would inform what health status changes are of value to affected individuals.
In this manuscript, I share with you an approach for lower extremity management that was developed over many years with a consistent team of highly experienced pediatric practitioners who provided integrated and coordinated care for this population of children. Significant resources existed to facilitate ongoing communication with families managed by our clinic and to aid families in acquiring needed equipment and support. It is recognized that this is not the only approach that can be applied to this population.
CLASSIFICATIONS: WHAT ARE WE TALKING ABOUT?
Dr Judith Hall1–5 has greatly aided our understanding of the complexities associated with the myriad of diagnoses that are associated with joint contractures and dislocations. She has defined arthrogryposis as conditions with nonprogressive contractures present before birth. The estimated incidence of these disorders is 1:500 and includes deformities such as clubfoot and teratologic hip dislocation. Within this are children with arthrogryposis multiplex congenita (AMC) who have 2 or more affected areas. The estimated incidence of AMC is 1:3000 live births and includes more than 400 described conditions that have been linked to over 350 genes2. Of children with AMC, one third have predominantly limb involvement (eg, amyoplasia, distal arthrogryposis), one third have limb and other body areas (eg, pterygium syndrome, Larson syndrome, skeletal dysplasias), and one third have limb and central nervous system involvement (eg, myelomeningocele).2 For the rest of this manuscript, we will focus on amyoplasia.
CLASSIC TYPE ARTHROGRYPOSIS: AMYOPLASIA
Amyoplasia is a sporadic symmetric contracture syndrome that is the most common recognizable form of arthrogryposis. It is characterized by symmetrical limb involvement, some truncal sparing, normal to above average intelligence, and often a characteristic midline facial hemangioma.6
MANAGEMENT: STRATEGIES AND CONTROVERSIES
Conversations with parents of children with amyoplasia often begin in the prenatal period and will be filled with intense distress and often with parental guilt. It is important that information be factual, honest, and optimistic when discussing the impact and management of musculoskeletal deformities. In the neonatal period, when faced with the realities of the physical problems of the child, supporting the normal bonding of mother and child should be a priority followed by early management. The main goal of management of these children should be to improve independence. Although there is a large focus on ambulation as children, it is important to keep in mind that the priority skills to achieve independence for adults with physical disabilities have generally been ranked as: (1) communication skills; (2) activities of daily living; (3) mobility; and (4) walking. In addition, these children are intellectually normal at birth and management of their orthopaedic problems should not compromise cognitive and social development, meeting developmental milestones and nutrition and growth. Ideally, a pediatric physiatrist should help direct the overall management of the child.
The contractures associated with arthrogryposis are most severe at birth. Some spontaneous improvement is expected, but serial casting for correction for a limited period of time and splinting to maintain position after casting or after surgery is useful.7–10 Physical therapists should be involved soon after birth to teach the family stretching and passive range of motion for the joints. Therapy is important in the first 4 months of life. Manipulation of deformities initiated soon after birth can improve range of motion, can preserve and enhance muscle growth, and may remove or decease the need for surgery. Ultrasound can be useful to demonstrate the quantity of muscle mass. Muscle strength has been shown to affect motor function to a greater extent than joint contractures and attention should focus on maintaining muscle.11 Over time, the focus of therapy should be to enhance function and independence.
Other general principles to be mindful of during the management of children with amyoplasia include:
- Different does not always equate with better function or improved quality of life.
- Preservation of childhood experiences and of a family structure may be more important than limited functional or care gains.
- Minimizing the number of surgical and recovery episodes for a child by combination surgeries can mitigate the impacts of surgeries upon a child’s development.
- Nighttime splinting and short periods of recasting can aid in slowing the recurrence of deformities over time and decrease the number of requisite operative procedures needed to maintain function.
- Assistive aids and devices can accommodate residual deformities and provide for functional gains.
- Whenever possible, attempt to correct residual deformities at maturity rather than during childhood.
Historically, children with moderate to severe amyoplasia who receive no treatment are believed to have no ambulatory potential and limited capacity for independent living skills. Series have reported varying degrees of functional ambulation in 50% to 78% of patients,12–15 but included patients with different types of arthrogryposis and treated with varying surgical procedures. A report by Sells et al16 demonstrated 85% of 38 children with amyoplasia achieving functional ambulation by the age of 5 years with surgical intervention. Kroksmark et al11 have reported a group of patients with amyoplasia, which are indistinguishable in the newborn period and respond dramatically to physical therapy. All series11–18 suggest an optimistic childhood with peak function occurring by age 10 years and some decline in ambulation into the adult years. Assessment for this potential can be difficult with decisions of the extent and timing of surgery hanging in the balance. In our experience, this is often definable by 2 to 3 years of age. A multidisciplinary evaluation of the child to assess their ambulatory and functional potential is important. Serial evaluations involving physical therapy and physiatrists are important. Hoffer et al15 and Staheli18 have characterized children with ambulatory potential as having: grade 4 or greater hip extensors or shoulder depressors; hip flexion contracture <20 degrees; grade 4 quadriceps function; grade 3 quadriceps function with knee flexion contracture <20 degrees; good torso strength and sitting balance with shoulder depressor function and only mild upper extremity abnormalities.
Similarly optimistic outcomes have been reported related to the functional independence for children with amyoplasia. Carlson et al19 and Hahn14 reported 70% had no limitations in daily activities and “reasonably independent” function in their patients, respectively, with most patients remaining partially dependent upon others. Sells et al16 reported that 64% of their patients were age appropriate in school, 75% were independent for feeding, 20% for grooming, 10% for dressing, 35% for toileting, and 25% for bathing.
Despite these reports, many children with amyoplasia will not have ambulatory potential. Hall2,20 has identified a “severe type” arthrogryposis as a subgroup of children who would be unlikely to be able to achieve functional ambulation. Similarly, we have found that children who have cognitive impairments are less likely to successful in ambulation programs. What may aid ambulation, may adversely impact sitting and vice versa. This will affect the indications for, type of, and staging of the multiple surgeries necessary. An estimate of the relative potential impact of deformities and rehabilitative services upon ambulation and sitting is shown in Table 1.
Extremity Involvement in Amyoplasia
Fifty-six percent will have involvement of all 4 limbs (7% severe), 5% 3 limb, 16% will have leg only, and 17% will have arm only involvement.20 Approximately 10% of patients will have abdominal structure abnormality, and 55% to 70% will have some form of genital abnormality.16,18 The shoulders are down slopping and internally rotated. Elbows are normally extended, forearms pronated with flexion deformities of wrists and fingers. Lower limb involvement most often includes severe talipes equinovarus (clubfoot) deformity with either flexed or extended knees. Hips may be flexed and externally rotated or extended and subluxated or dislocated. The incidence of reported deformities is shown in Table 2.21
The Lower Extremities
What follows is a review of common deformities and existing literature regarding treatment.
Approximately 80% of children with amyoplasia will have involvement of the hip ranging from soft tissue contractures, to unilateral or bilateral hip dislocations in 15% to 30% of patients.9,22,23 Many isolated external rotation or abduction contractures will spontaneously improve over time and will only occasionally require surgery. Hip flexion contractures are less likely to occur in isolation, but if >30 degrees may interfere with ambulation and if >45 degrees will generally require release for ambulation. Often the combination of hip flexion, external rotation, and abduction contractures are present. In these cases, the hip abductors may function as extensors and if the hip is left in external rotation, the hip can often be adducted to neutral and extend to <30 degrees of contracture without soft tissue releases while preserving good hip extensor strength for standing. A distal femoral osteotomy is necessary to bring the knee and foot into alignment for ambulation.
Early reduction is recommended for unilateral dislocation in all reports. Closed reduction is generally unsuccessful in achieving a stable long-term reduction.23,24 Open reduction by an anterolateral approach with or without pelvic and femoral osteotomy has been reported most often, but has been associated with hip stiffness.9,22,23 The medial approach has been used with success and less stiffness than that reported by the anterolateral approach.9,22,25 Medial open reduction is associated with less AVN but a higher rate of redislocation or subluxation than anterolateral approach.9,22,24,26 The risk of AVN in teratologic hips treated by anterolateral approach can be decreased with concomitant femoral shortening osteotomy. There continues to be controversy with regard to the treatment of bilateral hip dislocations. Historically, most authors have recommended nonoperative treatment because bilateral hip dislocation alone has not been thought to prevent ambulation and due to concerns about iatrogenic stiffness and avascular necrosis.27 Advocates of medial approach open reduction have recommended reduction of bilateral dislocations and claim improved ambulation potential and quality of gait.26 Successful reduction of bilateral hip dislocation may increase ambulation potential.23
Our approach is to perform medial open reduction at 6 to 12 months in unilateral and bilateral cases, reserving anterolateral with femoral osteotomy approach for the older child or redislocation. For children older than 12 to 18 months of age the likelihood of needing a concomitant pelvic osteotomy is higher raising the risk of increased hip stiffness after treatment. For this reason, we recommend against open reduction of bilateral dislocations in children older than 18 months.
Knee abnormalities are present in 70% of children with amyoplasia with flexion deformities in 48%, extension deformities in 21%, and dislocation in 4%.18 Treatment will generally change the relative arc of movement, but not increase it. Initial treatment should focus on therapy and splintage. The goal is to optimize knee flexion for sitting, but not lose active or passive extension for standing. This is best accomplished if there is <20 degrees of flexion contracture and at least 60 degrees of passive flexion.
Hyperextension deformities generally will respond well to therapy or splinting. Pavlik harness can be use if 60 degrees of flexion can be achieved. Knee dislocations should be reduced early and will usually require surgery. If treated early (1 to 3 mo) percutaneous quadriceps tenotomy with serial casting has been successful.28 When treated later more extensive soft tissue procedures, V-Y plasty with anterior capsulotomy and sometime sectioning of the posterior cruciate ligament or bony procedures are required, such as femoral shortening flexion osteotomy. Walking ability in this group of patients is very good.29,30 Long-term studies have shown significant rates of degenerative knee arthritis, more commonly associated with extension deformities.31,32 Knee reduction can be done simultaneously with hip reduction and clubfoot correction.
Flexion contractures are a more significant deformity both with respect to disability and resistance to treatment.17,29,32 Twenty-five percent of knees managed only by manipulation have a good response. Most are milder contractures.29 Knee flexion contractures generally need to be treated separately from the hips and feet due to the different position of immobilization needed after treatment. The decision for surgical management should be based upon a careful assessment of ambulatory potential. In our experience, this is often between 2 and 3 years of age. If the potential is believed to be poor, it may be best to accept the contractures and focus attention elsewhere. Treatment options have been related to the severity of the contracture. Flexion contractures of <20 degrees probably do not require treatment. Contractures of 20 to 40 degrees may respond to serial casting or to soft tissue release and tendon lengthening. Another alternative is to perform an anterior hemiepiphysiodesis in children with significant growth remaining. Although growth modulation is an attractive option for milder deformities, there is not yet a reported series of successful improvement in apparent flexion deformities in children with amyoplasia using this method. Contractures >40 degrees may be helped by initial casting and have been managed by either extension osteotomy or soft tissue release and femoral shortening or serial casting. With extension osteotomy, there can be concurrent femoral shortening and correction of external rotation, but there is a significant cosmetic deformity and a recurrence rate of 1 degree per month that is likely to require a repeat osteotomy unless done near the end of growth.33,34 For very severe contractures >80 degrees current options for treatment include soft tissue release with femoral shortening or gradual correction with Ilizarov external fixation methods.35 Historically, amputation has been suggested, but in our opinion, this should be viewed only as a salvage procedure. In our experience, soft tissue releases with a femoral shortening and derotational osteotomy followed by serial casting can reliably achieve and maintain a functional knee position for ambulation in all but the most severe deformities.
Foot deformities are common in both amyoplasia and in distal arthrogryposis. Talipes equinovarus (clubfoot) is the most common with an incidence of 78% to 90%.36 Other deformities include congenital vertical talus 3% to 10%, metatarsus adductus, and calcaneovalgus. The short stiff foot may be the only manifestation of a distal arthrogryposis.37 The aim of treatment is a plantigrade braceable foot.
Casting has been recommended in an attempt to achieve some correction followed by surgery.8,10,14,16,18,29,38 Complete correction is difficult or even impossible, with any correction generally being lost quickly once casting is discontinued.37 It has been recommended to perform the Ponseti method manipulation and casting in the initial period of treatment, but there are no published reports of outcomes and Ponseti has confirmed that success with his method is difficult or impossible for amyoplasia.37 Our own experience has been that the method may work well for clubfeet associated with distal arthrogryposis. Alvarez et al have reported the use of botulinum A toxin into the triceps surae muscle as an adjunct to serial casting for arthrogrypotic children with mild to moderate clubfoot deformity.39
Most authors prefer circumferential release as the initial surgical procedure. Secondary procedures like calcaneo-cuboid fusion or cuboid osteotomy have been performed concurrently in 56%.40,41 Most of the patients in these series were not treated early nor did they have a complete subtalar joint release. Clubfeet treated by circumferential release have recurrence rates ranging up to 73% with secondary procedures being performed in 49%.7,36,38,42 Tendon resection rather than lengthening is recommended.36,43 Recurrence after soft tissue release can be decreased if long-term bracing is used, and can be improved with casting.7 Some authors have reported the use of talectomy as a primary procedure with satisfactory results ranging from 45% to 56%.40,41,44,45 The patients in these series have mostly been older or have had talectomy as a salvage procedure. When performed as a revision procedure the rates of satisfactory outcomes improve to up to 82%.7,38,46 The most common reasons for failure of the procedure are poor technique with either incomplete excision of the talus or malposition of the talus under the tibia causing the foot to drift posterior and into equines.44 There is not a consistent salvage procedure for failed talectomy and many authors reserve it as a salvage procedure for this reason.8,34,36,38,40,45,47,48
For the severely relapsed clubfoot, spatial frame or Ilizarov external fixator treatment with osteotomies can be used as a salvage procedure35,49 with successful outcomes in 90% to 100% of selected patients in experienced centers.49 Triple arthrodesis as a salvage procedure should be reserved for children 10 to 12 years.40,46,47
Staging and Timing of Interventions
The management of deformities associated with amyoplasia can be difficult as numerous procedures are necessary. Williams50 suggested that feet be corrected at 4 weeks, knees at 8 weeks, and hips at age 6 to 8 months. It is our opinion that these children should have a multidisciplinary evaluation to look at development and potential for ambulation. Although earlier correction is typically easier for clubfeet and hip dislocations, we believe that multiple simultaneous corrections result in fewer recoveries, less overall immobilization, and a socially better child. Postoperative casting requirements dictate possible combinations of procedures. Treatment of clubfeet, hyperextended knees, and hip dislocation can be performed at the same time at between 6 and 12 months of age. Knee flexion contractures, are probably best delayed in management until between 18 and 36 months of age. Partly, this is to allow time to assess for ambulatory potential, as a child with poor ability to ambulate may be best to be left with a flexion contracture. The skill of the treating surgeon and team should ultimately guide management decisions as performing bilateral 3-level surgery can be challenging and lengthy (Fig. 1).
Pitfalls of Treatment
For the surgeon who undertakes the surgical management of children with amyoplasia, it is important to have colleagues who can aid in the management of the medical, anesthetic, and rehabilitative needs of these patients. The lack of integrated and coordinated team management of these patients increases the likelihood of adverse outcomes from surgical treatments. Similarly, operating on children who have developmental delays, families with limited support capabilities, and inadequate support for therapy and bracing after surgery severely limits the likelihood of achieving meaningful improvements in the health and functional status of these children. In such cases, recurrence of deformity and no change in function or disability would be the likely outcome.
In summary, the management of the musculoskeletal deformities of children with amyoplasia is extremely challenging, but can lead to reductions in disability and increases in mobility for selected patients. Integrated and coordinated team-based care is recommended to optimize the potential outcomes. Early combined surgical treatments can correct deformities and limit the adverse impacts upon childhood development and family support structures. In this manuscript an approach based upon management principles is presented that may aid practitioners in their approach to this group of patients.
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