Klinische, radiologische und arthroskopische Aspekte des Nagel-Patella-Syndroms (NPS): Literaturübersicht am Beispiel einer betroffenen Familie

Management of patellar problems in skeletally mature patients with nail-patella syndrome

PURPOSE

Nail-patella syndrome (NPS) or hereditary onychoosteodysplasia is a rare autosomal dominant disease, characterized by a tetrad of findings, which include fingernail abnormalities, hypoplasia of the patellae, radial head dislocation and prominent iliac horns. Most of the literature on the treatment of patellar problems in NPS concerns paediatric patients, and there is no standard treatment algorithm for adult patients.

METHODS

We reviewed the charts of skeletally mature patients with NPS who presented to our clinic. We reviewed the presenting complaints, the physical examination findings and the radiographic imaging.

RESULTS

We identified seven skeletally mature patients with NPS who presented with patellofemoral complaints. Their symptoms were instability, pain, or a combination of the two. Examination and imaging revealed a wide range of severity but included patellar instability and patellar arthritis. In our series, milder forms of the disease were treated with non-operative measures, but the majority of our patients required surgery including medial patellofemoral ligament reconstruction, tibial tuberosity transposition, patellofemoral and total knee arthroplasty. At midterm follow-up, most patients had good results.

CONCLUSION

Nail-patella syndrome has a wide range of presentations and severity in skeletally mature patients. Knee surgeons should be familiar with the spectrum of clinical presentation and the range of treatment options available in order to provide optimum treatment for patients with this disorder.

LEVEL OF EVIDENCE

IV.

Radiological characteristics of the knee joint in nail patella syndrome

Aim

Nail patella syndrome (NPS) is a skeletal dysplasia with patellofemoral dysfunction as a key symptom. We present the first in-depth radiological evaluation of the knee in a large series of NPS patients and describe the typical malformations.

Patients and Methods

Conventional radiological examination of 95 skeletally mature patients with NPS was performed. Patellar morphology was classified according to the Wiberg classification as modified by Baumgartl and Ficat criteria, and trochlear shape was classified according to the Dejour classification.

Results

Patellar aplasia was present in 4/90 (4%), and patellar hypoplasia in 77/90 (86%) of patients. The prevailing patellar shapes were type III, type IV and Hunter’s cap. No patellar shape genotype-phenotype association could be found. The malformations of the distal femur comprised shortening of the lateral femoral condyle in 46 out of 84 patients (55%), with a prominent anterior surface of the lateral femoral condyle in 47 out of 84 patients (56%) and a flat anterior surface of the medial femoral condyle in 78 out of 85 patients (92%). The trochlea was type A1 according to the Dejour classification in 79 out of 85 patients (93%).

Conclusion

An easily recognisable characteristic quartet of malformations consisting of patellar aplasiaor hypoplasia and the malformations of the distal femur was found in 22 out of 81 patients (27%), with the majority displaying at least three malformations. Take home message: The distinct malformations of the knee in nail patella syndrome are easily recognisable on conventional radiographs and lead to the correct interpretation of the aberrant morphology which is essential in the treatment of these patellofemoral disorders. Cite this article: Bone Joint J 2016;98-B:483–9.

Nail patella syndrome: Knee symptoms and surgical outcomes. A questionnaire-based survey

BACKGROUND

Patellofemoral instability and dysfunction are frequent symptoms in Nail patella syndrome (NPS). In this article, the first large series of NPS patients is presented in which these knee symptoms were assessed using validated outcome scores. Additionally, the need for surgical interventions, percentage of patients who received surgical treatment and patient reported outcomes are reported.

METHODS

A questionnaire based survey was conducted in 139 Dutch NPS patients. Symptoms of the knees were assessed by the Knee injury and Osteoarthritis Outcome Score (KOOS) and Kujala knee score. The questionnaire addressed whether surgical intervention was currently considered, history of past surgeries, type of surgical procedures performed and results of these procedures.

RESULTS

Response rate was 74%. Mean KOOS (73.04) and Kujala (74.01) scores showed a wide range and variability between patients. Patellofemoral instability was present in 48.5% of patients. Surgical intervention was currently considered by 12% of patients. Their KOOS and Kujala scores were significantly lower compared to those not considering surgery and they experienced more patellar instability. Surgery was performed on 31 knees in 23 patients. KOOS and Kujala scores were lower in surgically treated versus nonoperated patients but no difference in patellar instability was present. An improvement in pain in 87% and in function in 30% of knees was reported after surgery. Patient satisfaction with the surgical results was 61% and 10% was dissatisfied. Patellar realignment procedures showed similar results, although persistent patellar instability was reported in 40% of patients, not different from nonoperated patients.

CONCLUSIONS

Knee symptoms in NPS patients vary widely, with patellar instability present in nearly half of the patients. Although surgical treatment appears unfavourable as surgically treated patients have lower KOOS and Kujala scores, the patient reported surgical results are generally good with a high patient satisfaction.

LEVEL OF EVIDENCE

Level IV.

Correction of malformative patellar instability in patients with nail-patella syndrome: a case report and review of the literature

Nail-patella syndrome (NPS) or hereditary onycho-osteodysplasia is a relatively rare autosomal dominant disorder with the classic tetrad of fingernail abnormalities, hypoplastic patellae, radial head dislocation and iliac horns. The anatomic abnormalities in NPS often lead to subluxation or dislocation of the patellaeca causing knee instability and pain. Although most existing literature regarding the knee manifestation of this syndrome has focused on the clinically and radiological changes, only a few articles discussed the surgical treatment. This study reports the clinical, radiological and arthroscopical findings and a 24-month follow-up after operative stabilisation considering the underlying pathomorphology of malformative patellar instability in an 11-year-old girl. The findings of this study confirm the unique pathology of NPS with a synovial band preventing the engagement of the patella into the trochlear groove. NPS is a rare disorder and has to be considered in cases with untypical patella dislocation. The underlying pathology differs completely from patients with patellofemoral instability. The aim of orthopaedic surgery should be correction of the underlying pathology with resection of the synovial band and an additional realignment of the patella by recentering of the quadriceps muscle. Considering the underlying pathology good clinical results can be expected.

[Congenital radial head dislocation on both sides]

Both traumatic and congenital dislocation of the radial head are very rare in childhood. It can sometimes be difficult to tell them apart in practice. In this paper therefore, we present one case and discuss the various aspects of both conditions with reference to the available literature. Traumatic dislocation of the radial head is generally easily reduced without open surgery, and an open procedure is virtually never indicated in a patient who is still growing. In contrast, specific treatment of congenital radial head dislocation is not necessary because most patients are free of pain.