Patellar tilt, congruence angle, and tibial tubercle-trochlear groove distance are correlated with positive J-sign in adolescents.

PURPOSE: The J-sign is a clinical evaluation tool that assesses for patellar maltracking and is considered positive if lateral translation of the patella in extension, in the pattern of an inverted J is observed. This study aims to determine the association of clinical J-sign with imaging features noted on dynamic kinematic computed tomography (DKCT). METHODS: A retrospective review was conducted by reviewing the clinical records of all patients aged 18 years or younger who had a CT patellar tracking scan done between 1 January 2005 to 31 December 2016 in a single institution. Patients who had the presence or absence of a 'J-sign' evaluated clinically were included. Radiographic parameters evaluated using the axial cuts include the patellar tilt angle, congruence angle, Dejour's classification, femoral sulcus angle, trochlear groove depth, and Wiberg's classification. Patients were then divided into two groups based on the presence or absence of J-sign on clinical examination. The radiographic measurements were then analyzed for association with the presence or absence of J-sign on clinical examination. RESULTS: Patients with a positive J-sign had an increased patellar tilt of 23.3° ± 14.2° and an increased congruence angle of 47.1° ± 28.5° when measured in extension as compared to a patellar tilt of 18.3° ± 10.8° and a congruence angle of 32.1° ± 20.8° in patients with a negative J-sign (p = 0.024 and 0.004, respectively). Comparisons of the change in congruence angles with the knee in full extension and at 20° flexion also yielded significantly higher change of 28.0° ± 20.4° in patients with a positive J-sign as compared to 11.9° ± 17.5° in patients with a negative J-sign. Patients with a positive J-sign also had an increased TT-TG distance of 17.6 ± 5.6 mm as compared to a TT-TG distance of 14.7 ± 6.9 mm in patients with a negative J-sign (p = 0.01). CONCLUSION: Patients with a positive J-sign had an increased patellar tilt and an increased congruence angle when measured in extension. Increased TT-TG distance was also significantly associated with positive J-sign. Patients with a positive J-sign also had a greater change in their congruence angle when measured with the knee in full extension and at 20° of flexion.

Late presentation in adolescent idiopathic scoliosis: who, why, and how often?

Children and young teenagers with adolescent idiopathic scoliosis (AIS) not infrequently present with Cobb angles in excess of 40° at the first clinic visit. This study aimed to establish the incidence of this group of patients, identify the possible factors that may account for the late presentation, and make appropriate recommendations where applicable. This is an institutional review board-approved study. The index posteroanterior spinal radiographs of all 1176 AIS patients who presented to our institution between January 2007 and December 2011 were independently reviewed by two authors (J.Z.J.L. and K.B.L.L.). Patients with curves 40° or greater were included. An interviewer-administered survey was conducted by phone interview to obtain demographic information and identify possible factors for late presentation. The incidence of late presenters was found to be 5.5% (65/1176). The response rate was 73.8% (48/65). Twenty-four (50.0%) respondents acknowledged delaying seeking help after initial suspicion of scoliosis. The reasons cited most were that they were 'too busy' and 'did not know it was scoliosis'. Thirteen (27.1%) respondents attempted 'alternative' treatment before their first specialist appointment, of which 'Chinese Sinseh massage' was the most popular. Thirty-two (66.7%) respondents were not aware of AIS before their diagnosis. In conclusion, the incidence of late presentation in AIS is 5.5% in this series and significantly higher than the published figure of 0.1%. A time delay in seeking help because of a poor understanding of the condition and the failure to appreciate the importance of early specialist review may have contributed toward this relatively high incidence. Patient education and emphasis on timely specialist review can enhance and complement school screening to reduce the incidence of late presentation.