Daniel Dornacher

Observer Agreement on the Dejour Trochlear Dysplasia Classification A Comparison of True Lateral Radiographs and Axial Magnetic Resonance Images

Background: Trochlear dysplasia is known to be an important cause of patellofemoral instability. D. Dejour’s radiographic and magnetic resonance imaging (MRI) classifications are widely used in clinical practice and in the orthopaedic literature to assess the severity of trochlear dysplasia. The indication for deepening trochleoplasty to treat trochlear dysplasia is also mainly based on the severity of trochlear dysplasia according to Dejour’s criteria. Purpose: To our knowledge, there is no study evaluating the efficacy of the Dejour classification. The aim of this study was to assess the intraobserver and interobserver agreements of the radiographic and MRI-based classification as described by Dejour. Study Design: Cohort study (diagnosis); Level of evidence, 2. Methods: From 50 patients, 50 lateral radiographs as well as 50 MRI scans were read twice independently within 4 weeks by 4 surgeons (2 senior and 2 junior examiners). Analysis was made according to Dejour’s 4 grades of radiological criteria of trochlear dysplasia as well as differentiating between 2 grades: low-grade (type A) and high-grade trochlear dysplasia (types B-D). Results: The 4-grade analysis showed fair intraobserver and interobserver agreements (24%-78%), while the 2-grade analysis showed good to excellent agreement (56%-96%). The best overall agreement was found for the 2-grade analysis on MRI scans (62%-96%). The lateral radiographs tended to underestimate the severity of trochlear dysplasia compared with axial MRI. Conclusion: D. Dejour’s classification is valid for typing trochlear dysplasia and is particularly useful in separating low-grade from high-grade dysplasia.

Analysis of failed surgery for patellar instability in children with open growth plates

PurposeMany surgical procedures have been proposed to treat recurrent patellar dislocation in children. In recent years, a more tailored approach considering the underlying pathology has been advocated. The aim of the study was to analyze a group of patients with recurrent patellofemoral instability after unsuccessful operative stabilization (Roux-Goldthwait procedure, lateral release, medial reefing or in combination) in childhood and adolescence.MethodsA total of 37 children and adolescents with recurrent patellofemoral instability despite previous surgery were analyzed retrospectively. Radiographic examination included AP and lateral views to assess patella alta and limb alignment. MRI was performed to evaluate trochlear dysplasia and tibial tubercle-trochlear groove (TTTG) distance. As a control group, 23 age- and sex-matched adolescents that were treated with a favorable outcome after medial reefing alone or combined with a Roux-Goldthwait procedure were analyzed.ResultsSevere trochlear dysplasia (type B–D according to Dejour) as detected on MRI scans was found significantly more often in the study group (89%) than in the control group (21%). No statistical difference of patellar height ratio (Insall-Salvati index) and TTTG distance between the two groups could be found.ConclusionOf the measured parameters, only the incidence of trochlear dysplasia was increased. Trochlear dysplasia therefore seems to be a major risk factor for failure of operative stabilization of recurrent patellofemoral instability in children and adolescents. The results in children are in consensus with the literature in adults that a more tailored operative therapy including reconstruction of the MPFL and trochleaplasty has to be considered.Level of evidenceRetrospective study, Level III.

Early radiological outcome of ultrasound monitoring in infants with developmental dysplasia of the hips.

The purpose of this study was to evaluate the early radiological outcome after ultrasound-monitored treatment of developmental dysplasia of the hip (DDH) and to examine whether there was a correlation between the initial severity of DDH, measured by ultrasound, and the severity of residual dysplasia on the radiograph at the first follow-up. At the beginning of ultrasound-monitored treatment, the sonographic findings of 90 children (72 girls, 18 boys, mean age 7.2 weeks) with DDH (29 unilateral, 61 bilateral) were staged according to the Graf classification and assigned to four categories. Treatment was continued until normal ultrasound findings were reached. At the time children started walking (mean age 14.8 months), an anteroposterior radiograph of the pelvis was performed. The acetabular index was measured and classified according to the normal values of the hip joint, as described by Tönnis. The ultrasound findings expressed by the Graf classification were compared with the acetabular index measured at radiographic follow-up. Although normal values in ultrasound were reached before abduction splinting was discontinued, at the time of radiological follow-up, 59 hips (32.8%) showed mild residual dysplasia and another 53 hips (29.4%) showed severe residual dysplasia according to the criteria of Tönnis. Statistically, there was no significant correlation between the Graf classification and the radiological outcome at follow-up. Even after successful ultrasound-monitored treatment, a risk for residual dysplasia remains. Therefore, radiological follow-up of every hip treated once is necessary. We found no correlation between the severity of DDH measured by ultrasound and the subsequent presence of residual dysplasia at radiological follow-up.

Anatomical reconstruction of the medial patellofemoral ligament in children with open growth-plates

Recurrent lateral patellar dislocation is a common knee injury in the skeletally immature adolescent. In adults, anatomical reconstruction of the medial patellofemoral ligament (MPFL) is recommended, but due to the open physis, operative therapy in children is more challenging. We present a minimal invasive technique for anatomical reconstruction of the MPFL in children respecting the distal femoral physis. This technical note considers the important fact that the femoral insertion is distal to the femoral physis. Since the importance of an anatomical reconstruction respecting the femoral insertion of the ligament has been proven an insertion proximal of the physis has to be strictly avoided.

Mid-term results after ultrasound-monitored treatment of developmental dysplasia of the hips: to what extent can a physiological development be expected?

The purpose of this study was to evaluate the radiological outcome after ultrasound-monitored treatment of developmental dysplasia of the hip at the age of 3 years. We retrospectively reviewed the findings of the second radiographic follow-up of 72 consecutive infants (mean age 31.3 months) with residual developmental dysplasia of the hip. Statistical analysis showed significant regression of acetabular index. Nevertheless, nine hips in seven children showed substantial residual dysplasia. Although remodelling of the acetabulum can be expected, there remains a risk of residual dysplasia. For this reason, radiographic follow-up of every once treated hip as well as the initially physiological contralateral hip is necessary.

Impact of five different medial patellofemoral ligament-reconstruction strategies and three different graft pre-tensioning states on the mean patellofemoral contact pressure: a biomechanical study on human cadaver knees

BackgroundThe medial patellofemoral ligament (MPFL) is the main stabiliser of the patella and thus mostly reconstructed in the surgical treatment of patellofemoral dislocation. The aims of this study were to gain a better understanding of the influence of altered MPFL graft-fixation locations and different graft pre-tensions on patellofemoral contact pressure.MethodsSix human cadaveric knee joints were placed in a six-degree-of-freedom knee simulator. Mean PFCP (mPFCP) was evaluated in knee flexion of 0, 30 and 90° using a calibrated pressure-measurement system. After data assessment of the native knee joint, five MPFL reconstruction conditions were conducted: Anatomical double bundle; non-anatomical proximal patellar; non-anatomical distal patellar; non-anatomical proximal femoral; non-anatomical ventral femoral. The gracilis graft was fixed at a defined knee flexion of 30° and pre-tensioned to 2, 10 and 20 N.ResultsKruskal-Wallis testing resulted in no mPFCP differences between the native and anatomical reconstruction states.Comparing the native and anatomical reconstruction states with the non-anatomical reconstruction states, no difference in the mPFCP both in knee extension (0°) (p>0.366) and in 30° knee flexion (p>0.349) was found. At 90° knee flexion, the following differences were identified: compared to the native knee state, the mPFCP increased after non-anatomical proximal femoral and non-anatomical ventral femoral reconstruction by 257% (p=0.04) and 292% (p=0.016), respectively. Compared to the anatomical reconstruction state, the mPFCP increased after non-anatomical proximal femoral reconstruction by 199% (p=0.042).Discussion and ConclusionsWith respect to all study findings and to restore a physiological PFCP, we recommend using the anatomical footprints for MPFL reconstruction and a moderate graft pretensioning of 2-10 N.