J Knee Surg 2013; 26(05): 319-326
DOI: 10.1055/s-0032-1332805
Original Article
Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.

Radiologically Hyperdense Zones of the Patella Seem to Be Partial Osteonecroses Subsequent to Fracture Treatment

Jan Philipp Schüttrumpf
1   Department of Trauma Surgery, Plastic and Reconstructive Surgery, University Medicine Göttingen, Göttingen, Germany
Cyrus Behzadi
1   Department of Trauma Surgery, Plastic and Reconstructive Surgery, University Medicine Göttingen, Göttingen, Germany
Peter Balcarek
1   Department of Trauma Surgery, Plastic and Reconstructive Surgery, University Medicine Göttingen, Göttingen, Germany
Tim Alexander Walde
1   Department of Trauma Surgery, Plastic and Reconstructive Surgery, University Medicine Göttingen, Göttingen, Germany
Stephan Frosch
1   Department of Trauma Surgery, Plastic and Reconstructive Surgery, University Medicine Göttingen, Göttingen, Germany
Martin Michael Wachowski
1   Department of Trauma Surgery, Plastic and Reconstructive Surgery, University Medicine Göttingen, Göttingen, Germany
Klaus Michael Stürmer
1   Department of Trauma Surgery, Plastic and Reconstructive Surgery, University Medicine Göttingen, Göttingen, Germany
Karl-Heinz Frosch
2   Department of Trauma Surgery and Reconstructive Surgery, Surgery and Trauma Centre, Asklepios Clinic St. Georg, Hamburg, Germany
› Author Affiliations
Further Information

Publication History

11 October 2011

17 October 2012

Publication Date:
04 January 2013 (online)


The blood supply to the proximal patella is provided primarily via intraosseous vessels from the inferior patella. Two vascular systems within the patella are distinguished: Tiny arteries penetrate the middle third of the anterior patellar surface via vascular foramina and continue in a proximal direction. Additional vessels enter the patella at its distal pole, between the patellar ligament and the articular surface, and also run proximally. As a result of the double vascular supply to the distal portion and the vulnerable blood supply to the proximal part, localized osteonecroses subsequent to fracture may occur within the patella and nearly exclusively affect the upper portion of the patella. Such focal regions of osteonecrosis may appear radiographically as localized regions of hyperdensity within the patella. The aim of this study was to investigate the extent to which radiologically hyperdense areas, possibly representing localized osteonecrosis, may occur subsequent to surgical treatment of a patella fracture and the influence that they have on the outcome of the fracture. Retrospective analysis of 100 patients who had been treated operatively for a patella fracture from January 1998 to December 2008 was conducted. The subjective pain rating, clinical scores, and patient satisfaction scores were recorded. Existing X-rays were assessed with regard to possible increased radiological dense areas. After an average of 60.61 ( ± 33.88) months, it was possible to perform a clinical follow-up on 60 patients aged 45.48 ( ± 18.51) years. Radiographic follow-up of all patients revealed that nine patients (9%) exhibited a hyperdense area in the proximal patella portion. X-rays showed radiopaque areas between 1 and 2 months after surgery. In seven cases, the radiological finding disappeared after six months. In two patients with persisting radiologically dense areas, bone necrosis was verified by means of magnetic resonance imaging (MRI) examination and a histological assessment, respectively. The clinical outcome of these patients with a hyperdense area on the patella, in this small series, was not shown to be worse than those who demonstrated normal healing. Radiologically hyperdense areas subsequent to patella fracture may represent partial osteonecrosis caused by localized vascular compromise. This was confirmed by MRI and histological examinations in two patients with persistent hyperdense lesions. The clinical outcome of patients with hyperdense zones seems to be poorer than that of patients without such findings, but no statistical difference was shown in this small series. It is possible that earlier surgical treatment and thus a shorter ischemic period as well as tissue-conserving operative techniques could prevent the occurrence of partial necroses. This hypothesis would require further study.

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