Biomedical subjects

Sander Koëter

Publications and source records attributed to Sander Koëter.

4 recordsLinked to original sources

PubMed2006

A new CT scan method for measuring the tibial tubercle trochlear groove distance in patellar instability.

Patellar malalignment leading to objective or potential patella instability can be caused by tibial tuberosity lateralisation. This can be treated with a tuberosity medialisation. CT scan measurements are needed to assess the tibial tubercle trochlear groove distance. When using the previously described methods to determine this distance it can be difficult to determine the anatomical structures on the maximum intensity projection images, and this can lead to measurement error. This study was designed to compare the reliability of a new computer based CT measurement to the previously described method to determine the tibial tubercle trochlear groove distance. For each method, four observers measured each of 50 knees twice. The inter- and intra-observer variability for the conventional method and a new method were determined. Using the conventional method, the number of knees for which the difference between the aggregate mean of all eight measurements and the mean of duplicate measurements per observer greater than 2 mm varied among the observers between 7 and 24 for the 50 knees, while this variation between four and seven for the same 50 knees using the new method. The limits of reproducibility based on measurements from the four different observers improved by 25%, indicating that the measurement error is considerably smaller with the new method. We advise using this more accurate method to improve the selection of patients for a tuberosity medialisation.

Cohort Studies↗

PubMed2006

Conventional radiography cannot replace CT scanning in detecting tibial tubercle lateralisation.

Patellar instability can be caused by an excessive lateral distance between the anterior tibial tubercle and the trochlear groove (TT-TG). This study was designed to compare the TT-TG in reformatted computed tomography to the TT-TG on a 30 degrees axial conventional radiograph (CR) using lead markers to visualize the tibial tubercle and epicondyles. This is the first report on the use of lead markers for determining the TT-TG. Seven symptomatic knees in five patients (mean age 25 years, standard deviation 8.0 years) were investigated. Results showed that the tibial tubercle could be detected on 30 degrees axial CR by a lead marker. Determining the TT-TG however proved to be difficult. A good intra- and interobserver reliability (ICC >0.86) but large measurement error for the axial CR compared to CT was measured (Limits of Reproducibility as quantification of the measurement error was 18 mm for axial CR and 4 mm for CT). Because of the large measurement error for axial CR, the study was terminated after seven symptomatic knees. Positioning of the patient and markers, especially the tibial tubercle marker, probably are important factors leading to the large measurement error. Therefore, axial CR cannot replace CT to detect a pathological tubercle trochlear groove distance.

Adolescent↗

PubMed2006

Trochlear osteotomy for patellar instability: satisfactory minimum 2-year results in patients with dysplasia of the trochlea.

Trochlear dysplasia is a predisposing factor for recurrent patellar instability. We evaluated the results of an anterior lateral femoral condyle open wedge osteotomy for treating patellar instability. A total of 16 consecutive patients (19 knees) with symptoms of recurrent patellar instability and trochlear dysplasia identified using a true lateral radiograph of the knee underwent an anterior lateral femoral osteotomy. Outcomes were documented at 2 years minimum follow-up using the Lysholm scale, the patellofemoral score, WOMAC score and standard conventional radiographs. In 17 knees, patients reported good improvement in stability (no dislocations) and most patients had a marked improvement in pain and functional scores at follow-up (mean follow-up 51 months). No serious complications occurred. Anterior femoral osteotomy of the lateral condyle appears to be a satisfactory and safe method for treating patients with patellofemoral joint instability caused by trochlea dysplasia. In selected cases this procedure can be used to correct trochlea dysplasia. In our opinion, the key to a successful treatment of patellofemoral instability is to successfully distinguish the anatomic deficiencies and to correct the anatomical abnormality.

Adolescent↗

PubMed2006

Minimal rotation aberrations cause radiographic misdiagnosis of trochlear dysplasia.

Radiologic criteria are commonly used to diagnose femoral trochlear dysplasia causing patellofemoral (sub)luxations. A dysplastic trochlea can be identified on conventional radiographs when the line of the trochlear groove crosses the anterior border of one or both condyles. The aim of this study was to establish the influence of rotation on the precision of these radiographic criteria as classified on a true lateral conventional radiograph. In a radiological in vitro study using two different distal femurs we found that rotation deviations of the distal femur can simulate femoral trochlear dysplasia in a normal knee. In case of trochlear dysplasia, rotational deviations can simulate a normal trochlear shape with crossing of the trochlear groove with the anterior border of the femoral condyle. Even a rotation deviation of 5 degrees can cause a false-positive or false-negative diagnosis. We recommend the use of fluoroscopy to obtain a true lateral view (with both condyles overlapping on the posterior side) in order to correctly classify trochlear dysplasia and would strongly urge that no surgery should be performed on the basis of rotated conventional radiographs.

Cadaver↗