Sabine Lippacher

Anatomic Reconstruction of the Medial Patellofemoral Ligament in Children and Adolescents With Open Growth Plates Surgical Technique and Clinical Outcome

Background: Recurrent lateral patellar dislocation is a common knee injury in the skeletally immature adolescent. Because of the open physis, operative therapy in children is challenging. This study presents the outcomes of a minimally invasive technique for anatomic reconstruction of the medial patellofemoral ligament (MPFL) in children that respects the distal femoral physis. Hypothesis: Anatomic reconstruction of the MPFL in children that maintains the distal femoral physis will prevent redislocation, preserve the distal femoral physis, and improve knee function. Study Design: Case series; Level of evidence, 4. Methods: Twenty-one consecutive patients with patellofemoral instability and open growth plates underwent anatomic reconstruction of the MPFL that maintained the distal femoral growth plate. Preoperative radiographic examination included AP and lateral views to assess patella alta and limb alignment. Magnetic resonance imaging was performed to evaluate trochlear dysplasia and tibial tubercle–trochlear groove (TT-TG) distance. Evaluation included preoperative and postoperative physical examination, Kujala score, and Tegner activity score. Results: The average age at the time of operation was 12.2 years (range, 10.3-13.9). The average follow-up after operation was 2.8 years after surgery (range, 2.0-3.6). No recurrent dislocation occurred, but 2 patients with high-grade trochlear dysplasia still had a positive apprehension sign. The Kujala score significantly improved from 72.9 (range, 37-87) preoperatively to 92.8 (range, 74-100) postoperatively (P < .01). The Tegner activity score decreased, but not significantly, from 6.0 (range, 3-9) preoperatively to 5.8 (range, 3-9) postoperatively (P = .48). Conclusion: Anatomic reconstruction of the MPFL that respects the distal femoral physis in skeletally immature patients is a safe and effective technique for the treatment of patellofemoral instability and allows patients to return to sports without redislocation of the patella.

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.

Combined Trochleoplasty and Medial Patellofemoral Ligament Reconstruction for Recurrent Patellar Dislocations in Severe Trochlear Dysplasia A Minimum 2-Year Follow-up Study

Background: Trochlear dysplasia is an important etiological factor for the development of patellofemoral instability. Because a dislocation of the patella as a result of trochlear dysplasia results in a traumatic disruption of the medial patellofemoral ligament (MPFL), a combined trochleoplasty and patellofemoral ligament reconstruction appears to be the most appropriate procedure to treat patients with severe trochlear dysplasia. Hypothesis: Combined trochleoplasty and anatomic reconstruction of the MPFL will prevent redislocations of the patella and will lead to improved knee function. Study Design: Case series; Level of evidence, 3. Methods: Twenty-three consecutive patients (26 knees) with patellofemoral instability and severe trochlear dysplasia underwent combined trochleoplasty and anatomic reconstruction of the MPFL. Preoperative radiographic examination included anteroposterior and lateral views to assess patella alta. Magnetic resonance imaging was performed to evaluate trochlear dysplasia and the tibial tubercle–trochlear groove (TT-TG) distance. Evaluations included the detection of cartilage injuries, preoperative and postoperative physical examinations, and scores for the visual analog scale (VAS), Kujala knee function, International Knee Documentation Committee (IKDC), activity rating scale (ARS), and Tegner activity scale. Results: The mean age at the time of operation was 19.2 years (range, 15.4-23.6 years). The mean follow-up after operation was 2.5 years after surgery (range, 2.0-3.5 years). No recurrent dislocation occurred postoperatively. Kujala scores improved from 79 to 96, IKDC scores from 74 to 90, and VAS scores from 3 to 1. All improvements were highly statistically significant (P < .01). The activity level according to the Tegner activity scale and the ARS decreased but was not statistically significant (P = .06 and P = .21, respectively). There were 95.7% of the patients who were satisfied or very satisfied with the procedure. Conclusion: Combined anatomic reconstruction of the MPFL and trochleoplasty reliably improved the stability of the patellofemoral joint in patients with severe trochlear dysplasia and no or mild degenerative changes. In addition, the described procedure showed significant improvement of knee function and good patient satisfaction without any episode of redislocations of the patella.

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.

Reconstruction of the Medial Patellofemoral Ligament Clinical Outcomes and Return to Sports

Background: Recent studies have shown that medial patellofemoral ligament (MPFL) reconstruction using a standardized technique provides significant improvements in all outcome scoring systems, with low complication rates and good patient satisfaction. Although numerous studies have assessed clinical results, there is little published literature investigating return to sporting activities after reconstruction of the MPFL. Purpose: To demonstrate postoperative outcomes and the return-to-sports rate a minimum of 2 years after isolated MPFL reconstruction in a young patient cohort. Study Design: Case series; Level of evidence, 4. Methods: Between 2007 and 2010, a total of 72 isolated MPFL reconstructions (in 68 patients) were performed for recurrent patellar dislocation. Pre- and postoperative knee assessment included a thorough history of symptoms and a clinical examination consisting of crepitus, range of motion, patellofemoral pain, and patellar apprehension. Knee function was assessed using the Kujala score, International Knee Documentation Committee score, Tegner activity score, visual analog scale (VAS), and Activity Rating Scale (ARS). Results: Of patients who participated in sports preoperatively (62/68 patients), 100% returned to sports after MPFL reconstruction; 53% returned at equal or higher levels, whereas 47% returned at lower levels. Fifty-four of 68 patients (79.4%) rated themselves as very satisfied or satisfied with the results. The median Kujala score improved significantly from 66 to 87.5 and the median International Knee Documentation Committee score from 60 to 79.8. The median VAS for pain score illustrated significant preoperative to postoperative improvement, from 4 to 2. Conversely, patients’ activity levels according to the Tegner activity score dropped from 4.5 to 4, and the median Activity Rating Scale score dropped from 6 to 3. There was also a persistent instability rate of 10% as well as a slight loss of knee flexion in 24 of 72 knees. Conclusion: Reconstruction of the MPFL is a safe and effective treatment for patellofemoral instability without severe trochlear dysplasia and allows most patients to engage in regular sports activities 2 years postoperatively, at least at a recreational level. However, potential complications, such as persistent instability, pain, and loss of flexion, must be considered.

Reliability of radiographic signs for acetabular retroversion

Acetabular retroversion may contribute to femoroacetabular impingement and lead to osteoarthritis of the hip. Retroversion has been measured on computed tomography scans. In recent years, assessment of acetabular version on anteroposterior pelvic views has gained increasing attention. We therefore aimed to determine the reliability of radiographic signs of acetabular retroversion and its association with the rater’s experience. Five orthopedic surgeons (o1 to o5) rated the crossover sign, ischial spine sign and posterior wall sign on X-rays of 40 hip joints. Also, we determined the rater’s experience in recognizing acetabular retroversion with a questionnaire and correlated intraobserver reliability to the calculated experience score. The intraobserver results were 0.325 (o1), 0.848 (o2), 0.684 (o3), 0.701 (o4), and 1.000 (o5) for the crossover sign, 0.750 (o1), 0.890 (o2), 0.593 (o3), 0.483 (o4), and 0.946 (o5) for the posterior wall sign; and 0.578 (o1), 0.680 (o2), 0.595 (o3), 0.375 (o4), and 0.800 (o5) for the ischial spine sign. Interobserver reliability was 0.514 for the crossover, 0.633 for the posterior, and 0.543 for the ischial spine sign wall. The experience sum score correlated to the kappa results for the crossover (r=0.527), posterior wall (r=0.738), and ischial spine sign (r=0.949). Assessing acetabular version on plain radiographs is subject to intra- and interindividual error and related to the observer’s individual experience.

The effects of femoral external derotational osteotomy on frontal plane alignment.

AbstractPurpose Femoral osteotomies are the preferred treatment in significant torsional deformity of the femur. The influence of torsional osteotomies on frontal plane alignment is poorly understood. Therefore, the aim of the present study was to evaluate the effects of external derotational osteotomies on proximal, mid-shaft and distal levels onto frontal plane alignment.MethodsThe effect of rotation around the anatomical axis of the femur on frontal plane alignment was determined with a 3D computer model, created from CT data of a right human cadaver femur. Virtual torsional osteotomies of 10°, 20° and 30° were performed at proximal, mid-shaft and distal levels under five antecurvatum angles of the femur. The change of the frontal plane alignment was expressed by the mechanical lateral femoral angle.ResultsProximal derotational osteotomies resulted in an increased mechanical lateral distal femoral angle (mLDFA) of 0.8°–2.6° for 10°, of 1.6°–5.1° for 20° and of 2.3–7.9° for 30° derotational osteotomy, indicating an increased varus angulation. Supracondylar derotational osteotomy resulted in a decreased mLDFA of −0.1° to −1.7° for 10°, of −0.2 to −3.7° for 20° and of −0.7 to −6.9° for 30° derotational osteotomy, indicating an increased valgus angulation. The effect increased with the amount of torsional correction and virtually increased antecurvatum angles. Mid-shaft torsional osteotomies had the smallest effect on frontal plane alignment.ConclusionThis three-dimensional computer model study demonstrates the relationship between femoral torsional osteotomies and frontal plane alignment. Proximal external derotational osteotomies tend to result in an increased varus angulation, whilst distal external derotational osteotomies tend to result in an increased valgus angulation. As a clinical consequence, torsional osteotomies have an increased risk of unintentional implications on frontal plane alignment.

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.

Radiological criteria for trochlear dysplasia in children and adolescents.

Trochlear dysplasia is a well-known cause for recurrent patellar instability. Besides clinical findings, the treatment is based on radiological diagnostic tools. In adults the characteristics of trochlear dysplasia are determined by magnetic resonance imaging (MRI) scans as well as on true lateral radiographs. For children there are no established criteria for the radiological diagnosis of trochlear dysplasia. This study was designed to evaluate if typical radiological findings of trochlear dysplasia on lateral radiographs in adults are also found in children and adolescents with open growth plates. We analyzed true lateral radiographs of children and adolescents with MRI-detected trochlear dysplasia. On lateral radiographs three factors were relevant: crossing sign (deepest part of the trochlea crosses the most anterior point of the lateral condyle), a supratrochlear spur or bump (bulge of the proximal trochlea), and a double contour (due to a hypoplastic medial condyle). In all patients with trochlear dysplasia at least one typical radiological finding usually found in adults could be documented. Only true lateral radiographs allow the diagnosis of trochlear dysplasia in children and adolescents with open physis to be made. MRI scans on a regular basis are, therefore, not mandatory although they are the diagnostic golden standard for the diagnosis of trochlear dysplasia.

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.