Congenital Knee Dislocation Case: Early Recognition, Multispecialty Care, and Treatment

AUTHORS:

Blaire Cote MD1; Jiyeon Koo, MD2; Chelsea Matthia, MD3
1University of Florida Pediatric Residency Program, Gainesville, Florida
2University of Florida Community Health & Family Medicine Program, Gainesville, Florida
3University of Florida Department of Pediatrics, Gainesville, Florida

CASE REPORT | PUBLISHED SPRING 2025 | Volume 45, Issue 2

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Abstract

We present a newborn girl diagnosed with idiopathic congenital unilateral knee dislocation at birth. Genetic and pediatric orthopedic surgery evaluations were completed to optimize outcomes and identify underlying conditions. The low-grade dislocation was managed conservatively with soft splinting, followed by applying a Pavlik harness, resulting in complete correction within five weeks. Notably, serial casting—typically utilized in nonsurgical management—was not required. This case highlights the effectiveness of conservative therapy as a first-line treatment for congenital knee dislocations, particularly in milder presentations. Prompt recognition and early intervention are essential by the general pediatrician or newborn nursery pediatrician to prevent hip or gait abnormalities.

Primary Objective

This case report aims to review the rare presentation of congenital knee dislocation (genu recurvatum) in newborns, emphasizing early recognition and diagnosis by general pediatricians and newborn nursery pediatricians. This report aims to outline the multidisciplinary approach required for evaluation, discuss the effectiveness of conservative management strategies like the Pavlik harness in milder cases, and provide insight into prognosis and follow-up care. By sharing this case, we aim to enhance awareness of congenital knee dislocation and its implications for clinical practice, including potential syndromic associations.

Background

Congenital knee dislocation (genu recurvatum) is a rare condition, occurring in approximately 1 in 100,000 live births, and may present as either bilateral or unilateral.¹ Intrinsic causes often include genetic conditions such as Larsen syndrome and arthrogryposis multiplex congenita, while extrinsic factors may involve compression, breech presentation, and oligohydramnios.² Prenatal diagnosis is possible in some cases, although most cases are identified postnatally.

Recent classification systems for congenital knee dislocation have delineated three types: Type I, characterized by simple hyperextension; Type II, involving anterior tibial subluxation reducible with flexion; and Type III, defined by true anterior tibial dislocation.3,4 Treatment options vary and may include serial casting, physical therapy, or surgical intervention, depending on the severity of the condition. The prognosis can range from excellent to poor, contingent upon the underlying cause and the presence of associated anomalies.⁵

Subject Presentation

A female infant was born cephalic at full term with APGAR scores of 8 and 9 via uncomplicated repeat cesarean delivery. The mother had a medical history notable for a seizure disorder (not requiring medication), obesity, and spinal surgeries, and a previous child with a ventricular septal defect. A detailed anatomical ultrasound performed at 31 weeks gestation revealed no fetal anomalies, although visualization was limited by gestational age and fetal position. Upon delivery, a prominent deformity was noted to the right lower extremity, with the hip flexed and the knee hyperextended to approximately 240 degrees. The infant did not appear in distress, and passive flexion to 90 degrees was achievable (Figure 1).

Figure 1: Patient with Congenital Knee Dislocation at Birth (left image – passive flexion to 180 degrees, right image – baseline hyperextension to approximately 270 degrees)

The patient was admitted to the newborn nursery under the care of the general pediatrician and resident team. On day 0 of life, pediatric orthopedic surgery recommended physical and occupational therapy, genetic consultation, and no immediate casting or surgical intervention. On day 1, a repeat physical examination revealed the right knee flexed at rest and active flexion to 90 degrees (Figure 2). The genetics team recommended spine imaging, a hip ultrasound at 46 weeks corrected gestational age, and outpatient follow-up. Spinal x-rays were normal. Physical and occupational therapy provided a soft splint for the right lower extremity to prevent knee hyperextension. The patient was discharged from the newborn nursery on day 2 of life.

Figure 2: Patient with Congenital Knee Dislocation on Day 1 (left image – baseline mild flexion, right image – flexion to 90 degrees)

On day 6, the patient was evaluated by pediatric orthopedic surgery in clinic, where she demonstrated stable range of motion from 15 to 130 degrees, stability to varus and valgus stress, and a normal hip examination. A Pavlik harness was applied with the knees flexed. The physical examination remained stable at the orthopedic follow-up visit on day 19. The Pavlik harness was removed on day 33 of life.

Her pediatrician reevaluated the infant at 6 weeks old, and she exhibited equal spontaneous movement of all four extremities, with a noted right hip click (Figure 3). Evaluation by Genetics was significant for appropriate linear growth with low concern for skeletal dysplasia, given appropriate growth and reassuring spinal x-rays. Genetic testing (Invitae Skeletal Disorders Panel) was completed with a negative result for Larsen syndrome. A CYP27B1 variant (c.1376G>A/p.Arg459His) was identified, indicating the patient is a carrier for vitamin D-dependent rickets. The newborn screening results were normal. A hip ultrasound performed at 8 weeks of life showed no evidence of developmental dysplasia of the hip.

Figure 3: Patient with Congenital Knee Dislocation at 6 Weeks

Discussion

Congenital knee dislocation (CKD), or genu recurvatum, is a rare condition affecting approximately 1 in 100,000 newborns, with a higher prevalence in females.¹ CKD may be an acquired disorder or an isolated condition associated with genetic syndromes. It is most frequently linked to congenital hip dislocation, occurring in about 1% of cases.⁶ Other associated syndromes include Larsen syndrome, Collins-Pope syndrome, Desbuquois syndrome, Down syndrome, Ehlers-Danlos syndrome, Marfan syndrome, and arthrogryposis multiplex congenita.⁷ Due to the common association of CKD with genetic syndromes and congenital hip dislocation, a genetic evaluation and hip ultrasound are recommended for all CKD cases.⁸ For cases diagnosed prenatally, a detailed ultrasound and amniocentesis for genetic analysis are considered.2

At birth, CKD usually presents with knee hyperextension and anterior knee skin folds, with variations in reducibility and flexion. Confirmation of the diagnosis is achieved through plain radiographs, and management is based on CKD classification. The most recent and widely used classification system divides CKD into three types: Type I (simple hyperextension, easily reducible and stable), Type II (anterior tibial subluxation, reducible with flexion but unstable), and Type III (true anterior tibial dislocation, irreducible).³,⁴

Early orthopedic consultation is crucial, as treatment strategies differ based on the type of CKD. For Types I and II, initial management includes physiotherapy and using an anterior splint or Pavlik harness to promote knee flexion and maintain reduction. The splint or harness is typically used for 4 weeks for Type I and 6–8 weeks for Type II. If conservative treatments are ineffective, cast immobilization at 90 degrees of flexion for 3 weeks may be necessary, often followed by serial casting and eventual transition to a splint or harness.⁹ In more severe cases, such as Type III CKD, surgical interventions such as percutaneous quadriceps recession (PQR), V-Y quadricepsplasty (VYQ), and femoral shortening may be required.¹⁰

The prognosis for isolated lower-grade CKD cases without associated genetic disorders, such as this case, is generally favorable. A greater than 80% success rate has been demonstrated when intervention was initiated within the first two months of life.8 In contrast, poorer prognoses are observed in cases associated with genetic syndromes, limited knee flexion (less than 50 degrees), absence of anterior skin grooves, and delayed treatment. Such cases may lead to significant complications, including contractures or osteoarthritis.²

In conclusion, this case highlights the importance of early diagnosis and intervention in CKD to achieve optimal outcomes. Early recognition by the general pediatrician is essential, as early intervention has been associated with improved outcomes. Additionally, familiarity with this condition may enable prompt evaluation for comorbid diagnoses from broader syndromic associations. Multispecialty collaboration among general pediatrics, pediatric orthopedic surgery, genetics, and physical therapy ensures a comprehensive assessment and personalized treatment plan. By understanding diagnostic approaches, initial conservative management options, and recommended specialty evaluations, pediatricians can effectively manage mild to moderate cases and collaborate with specialists to optimize patient outcomes.

References

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