Case reportCongenital dislocation of the knee in a three-year-old-child with Larsen syndrome: Treatment with a hexapod-type external fixator
Introduction
Congenital knee dislocation (CDK) is a rare condition [1] that may occur alone or in association with other pathologies, such as Larsen syndrome (LS), arthrogryposis and Marfan syndrome. Larsen syndrome worsens the prognosis in CDK [2], which often requires surgery and is unlikely to resolve spontaneously [3]. The estimated incidence of this rare skeletal dysplasia is one per 250000 live births. The main clinical abnormalities include multiple dislocations of the knee, hip and elbow joints, clubfoot, relatively short stature, facial dysmorphism (hypertelorism, prominent forehead, and a depressed nasal bridge), cleft palate, and hearing loss. Reported skeletal features include joint dislocation, spinal anomalies (scoliosis and cervical kyphosis), anarchic carpal and tarsal ossification, short distal phalanges, and supranumerary carpal bones [4]. The FLN-B gene is responsible for LS, and the inheritance is dominant [5]. Larsen syndrome is classified as a filamin group and related disorder (group 7 in the international Nosology and Classification of Genetic Skeletal Disorders) [6].
Mehrafshan et al.'s new classification (based on the reductibility of the dislocation and the stability of the knee) distinguishes between three types of CDK: type I, reductible; type II, recalcitrant; and type III, irreductible [1]. Although the natural history of CDK has been described [1], [2], [3], [7], [8], [9], [10], [11], orthopaedic treatment at birth (physiotherapy, and use of a splint and cast for a few weeks to obtain and maintain the CDK reduction) is recommended for types I and II CDK [2]. For type III CDK, the methods for orthopaedic and surgical management remain subject to debate, and range from cast immobilization and axial traction [12] to surgical management with extensive quadriceps mobilization and percutaneous quadriceps tenotomy. A hexapod-type external fixator (HEF) is frequently used to correct three-dimensional deformations of the limb [13]. Here, we report on a case of CDK treated with an HEF.
Section snippets
Case report
A boy with a family history of hyperlaxity was treated in our department for knee dislocation. His mother had been treated for dislocations of both hips, and displayed a relatively short stature and facial dysmorphism. The boy had been born at term, and had normal birth parameters. A clinical examination at birth showed congenital dislocation of the knees. The knee joints' range of motion was 90° in extension and − 10° in flexion. No anterior skin grooves were present. Clinical and radiographic
Discussion
In the case reported here, orthopaedic treatment (the use of serial casts, splints, and an articulated orthosis from the first days of life onwards) was successful in treating dislocation of one knee (the left knee). Several non-invasive, therapeutic procedures have been described in the context of CDK: immediate reduction and physiotherapy, serial casts, a Pavlik harness, and skin or skeletal traction. All the experts agree that closed (non-surgical) reduction must be initiated during the
Conclusion
In view of the results obtained in the patient with LS described here, surgical treatment with an HEF should be considered as an option in type III CDK that is refractory to orthopaedic treatment. In view of the results obtained in this syndromic patient, the use of an HEF (sparing the knee extensor apparatus) may constitute a relatively advantageous alternative to quadriceps tenotomy.
Competing interest statement
None of the authors have any competing interests to declare.
References (20)
- et al.
Congenital dislocation of the knee at birth — part I: clinical signs and classification
Orthop Traumatol Surg Res
(2016) - et al.
Congenital dislocation of the knee at birth — part 2: impact of a new classification on treatment strategies, results and prognostic factors
Orthop Traumatol Surg Res
(2016) - et al.
Limb lengthening and deformity correction in children using hexapodal external fixation: preliminary results for 36 cases
Orthop Traumatol Surg Res
(2009) - et al.
The management of knee dislocation in a child with Larsen syndrome
Clinics (Sao Paulo)
(2011) - et al.
Congenital dislocation of the knee reduced spontaneously or with minimal treatment
J Pediatr Orthop
(1997) - et al.
Oral and craniofacial morphology of a patient with Larsen syndrome
J Craniofac Genet Dev Biol
(1986) - et al.
Mutations in the gene encoding filamin B disrupt vertebral segmentation, joint formation and skeletogenesis
Nat Genet
(2004) - et al.
Nosology and classification of genetic skeletal disorders: 2010 revision
Am J Med Genet A
(2011) - et al.
Assessment of clinical outcome of percutaneous needle quadriceps tenotomy in the treatment of congenital knee dislocation
Int Orthop
(2015) - et al.
A minimally invasive treatment protocol for the congenital dislocation of the knee
J Pediatr Orthop
(2009)
Cited by (7)
Larsen syndrome in a newborn with genu recurvatum
2024, Pediatrics and NeonatologyCongenital knee dislocation. Therapeutic protocol and long-term functional results
2021, Revista Espanola de Cirugia Ortopedica y TraumatologiaCongenital Knee Dislocation: Help for Neonatologists and Pediatricians
2023, Voprosy Sovremennoi Pediatrii - Current PediatricsAnalysis of early treatment of 12 cases with congenital knee dislocation
2022, Chinese Journal of Applied Clinical PediatricsCurrent views on the management of congenital dislocation of the knee based on current data on the outcomes of orthopedic treatment in these patients
2021, N.N. Priorov Journal of Traumatology and OrthopedicsCharacteristics and Usage Modalities. Main Systems
2021, Hexapod External Fixator Systems: Principles and Current Practice in Orthopaedic Surgery