Logo American Journal of Case Reports

Call: 1.631.629.4328
Mon-Fri 10 am - 2 pm EST

Contact Us

Logo American Journal of Case Reports Logo American Journal of Case Reports Logo American Journal of Case Reports

14 May 2024: Articles  USA

Congenital Dislocation of the Knee in the Delivery Room

Congenital defects / diseases

Benjiman J. Wilebski ORCID logo1ABCDEF, Ambereen Alam2DEF, Russell R. Lambert3DEF, Miltiadis Douvoyiannis ORCID logo4ABCDEFG*

DOI: 10.12659/AJCR.943725

Am J Case Rep 2024; 25:e943725




BACKGROUND: Congenital dislocation of the knee (CDK) is rare and can cause significant distress in the delivery room to parents and to healthcare providers, especially if the latter are unaware of this condition. It may not be detected by prenatal ultrasound and can be either an isolated finding or associated with other anomalies such as developmental hip dysplasia and genetic syndromes such as Larsen syndrome. Because of the risk of development of contractures, immediate referral to a specialized provider is needed. Poor prognostic factors include an association with a genetic syndrome, limited knee flexion related to severe quadriceps retraction, and absence of anterior skin grooves. A satisfactory outcome can be anticipated in isolated cases with easy reducibility of the knee.

CASE REPORT: A term baby presented unexpectedly with left knee dislocation after delivery. The providers, unaware of the condition, immediately consulted the orthopedic service, who assisted in the diagnosis, and appropriate management was initiated. The baby had serial casting of the leg, which was applied for almost 3 months, with excellent results on the clinical examination.

CONCLUSIONS: CDK is a rare finding. The diagnosis is primarily clinical and radiographs are used to confirm and assess the degree of the dislocation. The degree of dislocation is important for management and prognosis. Interventions ranging from serial casting to surgery are required as soon as possible. As the CDK can be associated with genetic syndromes or other dysplasias such as developmental dysplasia of the hip and talipes equinovarus, further evaluation for these conditions is warranted.

Keywords: Knee Dislocation, congenital, Diagnosis, Classification, treatment


The estimated incidence of the congenital dislocation of the knee (CDK), also known as genu recurvatum, is reported in 1 per 100 000 live births, which is approximately 1% the incidence of developmental dysplasia of the hip [1]. It is twice as frequent in females than males and can occur as an isolated condition, but more often in association with other intrinsic/genetic abnormalities such as Larsen syndrome, arthrogryposis multiplex congenita, and Ehler’s-Danlos syndrome [2,3]. In addition, CDK can be associated with developmental dysplasia of the hip and talipes equinovarus [4–6].

Case Report

A 23-year-old woman (gravida 4 para 2 abortus 2 living 1) gave birth by normal vaginal delivery to a 3100-g male neonate at 39 weeks of gestation. The pregnancy was uncomplicated. The prenatal ultrasound was normal and did not detect any breech presentation or oligohydramnios. Apgar scores were 8 and 9 at 1 and 5 minutes, respectively. While examining the newborn, there was an apparent extension deformity of the left knee (reported as “backwards”) with approximately 45° of hyperextension (Figure 1). The left knee could passively flex to approximately 30°. The infant did not exhibit any signs of distress or pain during gentle manipulation of the left knee. The skin was warm and well-perfused with brisk capillary refill. Left knee anterior skin folds were present and there was no sign of talipes equinovarus (clubfoot). Barlow and Ortolani maneuvers do not demonstrate a “clunk.” The right extremity and the remainder of the physical examination were otherwise unremarkable.

A lower-extremity radiograph demonstrated subluxation/dislocation of the left knee with anterior translation of the tibia/fibula relative to the femur, and an abnormal anterior angulation at the knee with no fracture (Figure 2). Normal newborn care was ordered, and an orthopedic surgery consult was placed. Reduction of the knee was not attempted at initial evaluation. The neonate was referred to the pediatric orthopedic service in another institution, where the knee was non-surgically reduced, and serial casting was performed for 3 months. Upon conclusion of the treatment, the baby was examined by us and an excellent clinical outcome was detected with almost complete normal flexion and extension of the knee without any deformity. Final radiographs were not obtained. A hip ultra-sound did not detect any developmental dysplasia.


Mechanical anomalies that can lead to CDK include fetal mal-position such as entrapment of the leg under the mandible, oligohydramnios, prolonged breech position, primary contracture of the quadriceps tendon due to fibrosis, and anterior cruciate ligament malformation [7]. An intrinsic or genetic anomaly often associated with CDK is Larsen syndrome, which has a frequency of approximately 1 per 100 000 live births and is due to mutations within filamin B. Associated symptoms include facial dysmorphism, talipes equinovarus, joint hyper-elasticity, and multiple dislocations [8,9]. Other genetic syndromes associated with CDK include Desbuquois dysplasia (osteochondrodysplasia that presents with short stature/extremities, severe joint laxity with dislocation, osteopenia, kyphoscoliosis, and characteristic facies), Collins Pope syndrome (bilateral congenital dislocation of the hip, congenital heart defects, characteristic facies), Marfan syndrome, Ehler’s-Danlos syndrome, and Down syndrome (muscular hypotonia and ligamentous hyper-laxity) [2,10]. CDK is associated with congenital hip dislocations, but may also be seen with arthrogryposis, myelomeningocele, talipes equinovarus, cleft palate, and scoliosis [1,2]. A hip ultrasound is recommended if CDK is present. Of all CDK cases, hip dislocation is involved in 45%, talipes equinovarus and other feet deformities in 3%, and elbow dislocation in 10% [6]. A study of 51 infants with varying degrees of CDK found isolated hip instability in 11 limbs and isolated foot abnormality in 7 limbs [2]. The findings from our case demonstrated no associated facial dysmorphisms, other joint dislocations, or syndromes evident on the initial physical exam.

Incidental prenatal diagnosis of CDK by abdominal radiograph performed for another reason has been reported [11]. Prenatal diagnosis of CDK is challenging, as it is often undetected by ultrasound. In a recent review of 20 cases of CDK detected by prenatal ultrasound, the median gestational age at diagnosis was 20 weeks (range, 14–38 weeks) [12]. A 3-dimensional (3-D) with a real-time 3-D (4-dimensional) ultrasonographic evaluation seems advantageous, as it offers a more dynamic interpretation of the limb position and mobility [13]. During initial evaluation after birth, hyperextension of the knee is an obvious deformity to assess for, while evaluating anterior skin grooves is important for prognosis. Absence of anterior skin grooves typically demonstrates a long-standing dislocation of the knee and severe deformity, whereas a greater number skin folds correlates with a more recent in utero dislocation and more favorable prognosis [14,15]. In our case, the patient presented with anterior skin grooves.

Currently there is no consensus on the classification of CDK, but specific criteria are typically used to classify CDK [2,7,8]. Mehrafshan et al proposed a classification system based on reduction and stability of the knee [2]. Type I CDK is easily reducible, providing a reduction snap as the femoral condyles pass in flexion, while remaining stable in flexion. Type II provides a recalcitrant dislocation, reducible but unstable. If posterior anterior pressure is relaxed on the femoral condyles, iterative dislocation occurs. Lastly, type III is an irreducible dislocation. Other classifications such as that of Abdelaziz et al [7] classify CDK based on knee flexion range of motion (ROM) and femoro-tibial relationship through radiography. Grade I CDK is when ROM is >90° with simple recurvatum on radiography, while grade II demonstrates ROM between 30° and 90° with subluxation/dislocation evident on imaging. Grade III has <30° with dislocation on radiography. Among these 2 classification systems, there appears to be some overlap. Mehrafshan et al [2] evaluated ROM and found significant differences in flexion among type I, II, and III. Individuals classified under type I at initial evaluation demonstrated knee flexion ROM at 85° (10°–140°), type II at 34° (10°–110°), and type III CDK at −5° (−35°−18°). Our patient was likely grade II according to the Abdelaziz et al [7] classification since knee flexion at initial examination was approximately 30° and radiography showed subluxation/dislocation.

Common pathologic findings are a shortening of the quadriceps femoris tendon, a tight anterior articular capsule, and hypoplasia of the suprapatellar bursa [16]. Most authors recommend initiation of intervention as soon as possible to prevent contractures and to promote development of the anterior distal femoral epiphysis [16,17]. Among treatment options, the literature reports that conservative treatment with serial casting/bracing or surgery as potential options, depending on the classification. Rampal et al [8] suggest that conservative treatment for type I and II include therapy with quadriceps stretching and application of an anterior full-leg splint that will progressively change to increase knee flexion and maintain reduction over time. They achieved successful reduction of all type I cases and 11 out of 16 type II cases with this non-operative treatment. The remaining type II knees underwent progressive cutaneous limb traction until reduction, and 90° flexion of the knee was demonstrated on lateral X-ray. Then, cast immobilization was applied for 3 weeks, and an anterior splint for 4–6 weeks yielded stability. Limb traction and casts were used for type III as well, but less favorable results were obtained. Only 43% of type III achieved reduction and stability with traction and casts and the remaining knees required surgery. Surgical options commonly included percutaneous quadriceps recession and V or Y quadreps-plasty [7,8,18,19]. Complications of treatment include recurrence, greenstick fracture of the tibia during manipulation and casting, and development of valgus knee deformity after surgery [1,16,17].

Prognostic factors that correlate with better prognosis and lower rates of complications include reducibility and stability on primary neonatal examination and presence of anterior skin grooves [8,17]. Poor prognostic factors include an association with a genetic syndrome, knee flexion <50° (related to severe quadriceps retraction), and the absence of anterior skin grooves [8,16,17]. Our patient with CDK had anterior skin grooves and reducibility with stability yielding a more favorable outcome, although knee flexion was evaluated at approximately 30°, providing some less favorable factors.


Congenital dislocation of the knee is a rare finding. The diagnosis is primarily clinical and radiographs are used to confirm and assess the degree of dislocation, which is important for management and prognosis. Intervention, ranging from serial casting to surgery, is required as soon as possible. It may be associated with genetic syndromes but also with developmental hip dysplasia and clubfoot, and screening is warranted for these conditions. Further research should be done to improve prenatal detection of this deformity.


1.. Jacobsen K, Vopalecky F, Congenital dislocation of the knee: Acta Orthop Scand, 1985; 56; 1-7

2.. Mehrafshan M, Wicart P, Ramanoudjame M, Congenital dislocation of the knee at birth – Part I: Clinical signs and classification: Orthop Traumatol Surg Res, 2016; 102(5); 631-33

3.. Yeoh M, Athalye-Jape G, Congenital knee dislocation: A rare and unexpected finding: BMJ Case Rep, 2021; 14(1); e234881

4.. Curtis BH, Fisher RL, Heritable congenital tibiofemoral subluxation. Clinical features and surgical treatment: J Bone Joint Surg Am, 1970; 52; 1104-14

5.. Johnson E, Audell R, Oppenheim WL, Congenital dislocation of the knee: J Pediatr Orthop, 1987; 7; 194-200

6.. Dungy CI, Leupp M, Congenital hyperextension of the knees in twins: Clin Pediatr (Phila), 1984; 23(3); 169-72

7.. Abdelaziz TH, Samir S, Congenital dislocation of the knee: A protocol for management based on degree of knee flexion: J Child Orthop, 2011; 5(2); 143-49

8.. Rampal V, Mehrafshan M, Ramanoudjame M, 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; 102(5); 635-38

9.. Arora V, Pal S, Kulshreshtha S, Verma IC, A further case of Larsen’s syndrome: Clinical and genotypic challenges in diagnosis: J Pediatr Genet, 2020; 11(4); 298-303

10.. Vissers LELM, Lausch E, Unger S, Chondrodysplasia and abnormal joint development associated with mutations in IMPAD1, encoding the Golgi-resident nucleotide phosphatase, gPAPP: Am J Hum Genet, 2011; 88; 608-15

11.. Elchalal U, Ben Itzhak I, Ben-Meir G, Zalel Y, Antenatal diagnosis of congenital dislocation of the knee: A case report: Am J Perinatol, 1993; 10(3); 194-96

12.. Cavoretto PI, Castoldi M, Corbella G, Prenatal diagnosis and postnatal outcome of fetal congenital knee dislocation: Systematic review of literature: Ultrasound Obstet Gynecol, 2023; 62(6); 778-87

13.. Monteagudo A, Kudla MM, Essig M, Real-time and 3-dimensional sonographic diagnosis of postural congenital genu recurvatum: J Ultrasound Med, 2006; 25; 1079-83

14.. Bensahel H, Dal Monte A, Hjelmstedt A, Congenital dislocation of the knee: J Pediatr Orthop, 1989; 9(2); 174-77

15.. Shah NR, Limpaphayom N, Dobbs MB, A minimally invasive treatment protocol for the congenital dislocation of the knee: J Pediatr Orthop, 2009; 29(7); 720-25

16.. Ooishi T, Sugioka Y, Matsumoto S, Fujii T, Congenital dislocation of the knee. Its pathologic features and treatment: Clin Orthop Relat Res, 1993(287); 187-92

17.. Palco M, Rizzo P, Sanzarello I, Congenital and bilateral dislocation of the knee: Case report and review of literature: Orthop Rev (Pavia), 2022; 14(3); 33926

18.. Roy DR, Crawford AH, Percutaneous quadriceps recession: A technique for management of congenital hyperextension deformities of the knee in the neonate: J Pediatr Orthop, 1989; 9(6); 717-19

19.. Curtis BH, Fisher RL, Congenital hyperextension with anterior subluxation of the knee. Surgical treatment and long-term observations: J Bone Joint Surg Am, 1969; 51(2); 255-69

In Press

Case report  USA

A Prefixed Four-Trunk Brachial Plexus with Anomalous Anatomy of All Subsequent Divisions, Cords, and Termin...

Am J Case Rep In Press; DOI: 10.12659/AJCR.943866  


Case report  USA

Rapid Progression of Malignant Peritoneal Mesothelioma Mimicking a Postoperative Complication in a Young Wo...

Am J Case Rep In Press; DOI: 10.12659/AJCR.942948  


Case report  Italy

Columella Reconstruction Using a Bilateral Nasolabial Flap: A Case Report

Am J Case Rep In Press; DOI: 10.12659/AJCR.943913  


Case report  USA

Successful Surgical Extraction of an Embolized Iliac Vein Stent from the Right Heart: A Case Report

Am J Case Rep In Press; DOI: 10.12659/AJCR.943620  


Most Viewed Current Articles

07 Mar 2024 : Case report  USA

Neurocysticercosis Presenting as Migraine in the United States

DOI :10.12659/AJCR.943133

Am J Case Rep 2024; 25:e943133


10 Jan 2022 : Case report  Germany

A Report on the First 7 Sequential Patients Treated Within the C-Reactive Protein Apheresis in COVID (CACOV...

DOI :10.12659/AJCR.935263

Am J Case Rep 2022; 23:e935263

19 Jul 2022 : Case report  Saudi Arabia

Atlantoaxial Subluxation Secondary to SARS-CoV-2 Infection: A Rare Orthopedic Complication from COVID-19

DOI :10.12659/AJCR.936128

Am J Case Rep 2022; 23:e936128

23 Feb 2022 : Case report  USA

Penile Necrosis Associated with Local Intravenous Injection of Cocaine

DOI :10.12659/AJCR.935250

Am J Case Rep 2022; 23:e935250

Your Privacy

We use cookies to ensure the functionality of our website, to personalize content and advertising, to provide social media features, and to analyze our traffic. If you allow us to do so, we also inform our social media, advertising and analysis partners about your use of our website, You can decise for yourself which categories you you want to deny or allow. Please note that based on your settings not all functionalities of the site are available. View our privacy policy.

American Journal of Case Reports eISSN: 1941-5923
American Journal of Case Reports eISSN: 1941-5923