Acta Orthop zyxwvutsrqp Scand zyxwvutsr 1998; 69 (3): 291-294 291 zy Bone bruise of the knee Histology and cryosections in 5 cases Christoph Rangger, Anton Kathrein, Martin C Freund, Thomas Klestil and Alfons Kreczy We evaluated the histopathologic and cryosectional appearance of bone bruise injuries of the knee de- tected on MRI. Histologic evaluation of bone biop- sies from 3 patients revealed microfracturesof can- cellous bone, edema and bleeding in the fatty mar- row. Between intact lamellar bone trabecules, frag- ments of hyaline cartilage mixed with highly frag- mented bone trabecules were found. Postmortem specimens were obtained from 2 more patients, killed in motor vehicle accidents. MRI revealed bone bruise injuries of the lateral femoral condyle and of the lateraltibial plateau in 1 knee and anterior cruciate ligament disruption, a medial me- niscus tear and bone bruise injury of the tibial pla- teau and of the lateral femoral condyle in the other specimen. The specimens were embedded in physi- ologic saline solution and frozen to -30 c. By rota- tioncryotomy, 1 mm slices were removed from the surface of the specimens and documented on pho- tographs. Subchondral lesions and bleeding were found, corresponding to the MR images. Universitiitsklinik fur Unfallchirurgie, AnichstraOe 35, AT-6020 Innsbruck,Austria. Tel+43 51 2 504-2821. Fax -2824 Submitted 97-06-07. Accepted 97-1 2-22 zyxwvutsr Mink and Deutsch (1989) clarified bone bruise of the knee on MR imaging. The injury is not evident on plain radiographs. TI-weighted images showed a geographic and nonlinear area of signal loss involving the subcortical bone. On T2-weighted images, most of the lesions had increased signal intensity. The artic- ular cartilage was normal. Since then, bone bruise in- juries have been reported frequently in the knee (Mink and Deutsch 1989, Vellet et al. 1991, Murphy et al. 1992, Stallenberg et al. 1993, Stein et al. 1995, Zeiss et al. 1995, Rangger et al. 1996) and also in the wrist, the calcaneus, the foot and ankle, and in the hip (Kier et al. 1991, Laorr et al. 1995, Shih et al. 1995, Soudry and Mannting 1995). We have found no reports on the histology of bone bruise lesions. We report 5 cases with histology or cryosectional investigations. Patients and methods 3 patients without a history of trauma (1 woman aged 22 years, 2 men aged 40 and 28 years) underwent ar- throscopy for a suspected meniscus injury 4 weeks, zyxwvu 5 weeks and 8 weeks after the onset of pain. No previ- ous surgery had been performed. Anteroposterior and lateral weight-bearing radiographs of the involved knee and an axial view of the patella were normal. MR imaging performed before surgery revealed a bone bruise in the lateral tibial plateau of 2 patients, and in the anterior central part of the tibial plateau in the third patient (Figure 1). During arthroscopy, subchondral biopsies for histologic evaluation were obtained with a cannulated drill through a separate in- cision. All patients were informed and gave written consent to the biopsies. At arthroscopy, in 2 patients the articular surfaces, the ligaments, and the menisci were found intact. In the third patient, tears in the medial and lateral meniscus were treated by partial meniscectomy. These patients form part of a prospec- tive series of MRI investigations before arthroscopy (Rangger et al. 1996). Specimens were obtained from another 2 patients, who died only days after motor vehicle accidents. Clinical examination after admission to the hospital and immediately after the patients had died, suggest- ed anterior cruciate ligament rupture in one and intact cruciate ligaments in the other knee. Plain radio- graphs were normal. Both postmortem specimens im- mediately underwent MRI evaluation. They were then placed in physiologic saline solution and frozen to -30 OC. Using a rotating shaft with blades, 1 mm slices were cut from the surface of the frozen speci- mens and photographed (Kathrein et al. 1996). MRI was performed with various supraconducting magnets (0.5-1.0 Tesla) and various pulse sequences, Copyright zyxwvutsrqpo 0 Scandinavian University Press 1998. ISSN 0001-6470. Printed in Sweden - all rights reserved. Acta Orthop Downloaded from informahealthcare.com by 117.172.98.97 on 05/20/14 For personal use only.