Osteochondritis Dissecans of the Knee
Sonographically Guided Percutaneous Drilling
Juan D. Berná-Serna, MD, Francisco Martinez, MD, Manuel Reus, MD, Juan D. Berná-Mestre, MD
Objective. The purpose of this study was to present a procedure for sonographically guided percuta-neous drilling in the treatment of a case of osteochondritis dissecans (OD) of the knee. Methods. A 14-year-old boy had OD of the external femoral condyle. Conventional radiography, magnetic reso-nance imaging, and sonography revealed the osteochondral lesion. Results. This study showed the utility of sonography both in the treatment of OD through percutaneous drilling and in follow-up. Conclusions.On the basis of the good results obtained in the case described here, it is thought that sonographically guided percutaneous drilling may be a good alternative to arthroscopic drilling in cases of early OD lesions without displacement of the fragment. Key words:knee; magnetic resonance imaging; osteochondritis dissecans; percutaneous drilling; sonography.
Received July 24, 2007, from the Department of Radiology, Virgen de la Arrixaca University Hospital, El Palmar, Murcia, Spain. Revision request-ed August 15, 2007. Revisrequest-ed manuscript acceptrequest-ed for publication September 5, 2007.
Address correspondence to Juan D. Berná-Serna, MD, Department of Radiology, Virgen de la Arrixaca University Hospital, 30120 El Palmar, Murcia, Spain.
E-mail: [email protected]
Abbreviations
MR, magnetic resonance; OD, osteochondritis disse-cans; TE, echo time; TR, repetition time
steochondritis dissecans (OD) is a common condition in children, adolescents, and young adults. Osteochondritis dissecans of the knee is a lesion of uncertain etiology. Mechanical and traumatic factors are etiologically dominant in OD.1–3
Commonly, OD occurs at the medial femoral condyle and less frequently at the lateral femoral condyle.3
Osteochondritis dissecans is generally diagnosed by con-ventional radiography. Its therapy is determined by the stage of the lesion, and magnetic resonance (MR) imag-ing is the method of choice for stagimag-ing.
Treatment of OD in the adult knee can be challenging. The treatment options include lesion debridement, drilling, microfracturing of subchondral bone, and trans-plantation techniques (autologous chondrocyte implan-tation, autologous osteochondral transplanimplan-tation, and osteochondral allografts).3–5We are not aware of any
pre-vious reports of sonographically guided percutaneous drilling in the treatment of a subchondral lesion of the knee.
Case Description
A 14-year-old boy, a basketball player, was referred to an orthopedic surgeon at our hospi-tal with pain in the right knee that prevented him from practicing his sport. In the initial phys-ical examination, the patient had pain in the anteroexternal sector of the right knee. His range of mobility was complete.
The diagnosis of OD of the external femoral condyle of the right knee was reached by the fol-lowing imaging techniques: (1) plain radiogra-phy (Figure 1A); (2) MR imaging, which revealed an osteochondral lesion of the external femoral condyle (Figure 1, B and C) with a line of high signal intensity between the OD fragment and the underlying bone; stage II OD was estab-lished according to the MR imaging classifica-tion proposed by Bohndorf1; and (3) sonography
(Figure 1, D and E), which revealed the subchon-dral lesion (Figure 1F).
The treatment carried out consisted of percu-taneous drilling of the OD lesion guided by sonography and with arthroscopic confirma-tion. The technique was previously explained in detail to the patient and his family, and written consent was obtained. The surgical procedure consisted of the following steps. First, a preop-erative sonographic examination was per-formed with the leg in maximal flexion. The area of the lesion was determined by means of sagit-tal and transverse sections, and this area was marked on the skin in indelible ink (Figure 1G). Then, puncture of the subchondral bone was performed, in which 3 percutaneous drillings were made in the area marked on the skin, with the patient anesthetized, the leg in maximal flexion, rigorous aseptic measures, and sono-graphic verification. Arthroscopy then con-firmed that the drillings had been made in the area of the subchondral lesion. The lesion was then pinned with biodegradable polylactic acid pins (Intra Fix Smart Nails; Conmed-Linvatec, Tampere, Finland).
In the immediate postoperative period, the patient started with progressive mobility with-out support and then underwent rehabilitation with muscle strengthening. After 1 month, he was allowed to increase his efforts progressively. Imaging studies with plain radiography, MR
imaging, and sonography (Figure 2) carried out 2 months after the operation showed a partial repair of the osteochondral defect. Imaging studies, sonography, and plain radiography car-ried out 20 months after the operation showed complete resolution of the lesion (Figure 3).
Figure 1. Preoperative images of OD of the external femoral condyle. A, Anteroposterior radiograph showing an OD lesion (arrow). B, Sagittal T2-weighted spin echo MR image (repetition time [TR], 4120 milliseconds; echo time [TE], 106 milliseconds) showing a lesion (arrow) with decreased signal intensity and a rim of high signal intensity surrounding the lesion (continued).
B A
F E
G C
D
Figure 1. (continued) C, Sagittal T1-weighted gradient echo MR image (TR, 500 milliseconds; TE, 20 milliseconds) at the same level as Bshowing a rim of high signal intensity surround-ing the lesion (arrows). D, Sonographic examination and trans-ducer position for assessing the femoral condyle. E, Longitudinal sonogram showing subchondral bone (arrow) of the normal knee joint; ac, indicates articular cartilage; F, femur; and T, tibia. F, Longitudinal sonogram showing subchondral bony flattening (arrows). G, Area of the lesion marked on the skin (arrow). P indicates patella.
Discussion
Osteochondritis dissecans of the knee can cause substantial patient morbidity and is difficult to treat because of the poor autoreparative capabil-ity of cartilage.4The diagnosis of OD is based on
its plain radiographic appearance, although MR imaging is the technique of choice to determine the stability of the lesion. One of the few studies reported on the evaluation of OD of the knee by use of sonography was that of Gregersen and Rasmussen.6 The efficacy of sonography has
been shown in evaluation of OD lesions of the
C B A
Figure 2.Images obtained at follow-up 2 months after drilling. A, Anteroposterior radiograph showing partial filling of the sub-chondral defect (arrow). B, Sagittal T2-weighted fast spin echo MR image (TR, 4120 milliseconds; TE, 106 milliseconds) showing one of the trajectories of the drillings in the subchondral lesion (arrows). C, Longitudinal sonogram showing partial filling of the defect and the holes of the drillings (arrows).
B A
Figure 3.Images obtained at follow-up 20 months after drilling. A, Anteroposterior radiograph showing complete resolution of the osteochondral defect. B, Longitudinal sonogram showing a fragment similar to the adjacent subchondral bone with a smooth surface and 1 defect (arrow) corresponding to a drilling.
humeral capitellum.7The sonographic features
of OD depend on the evolutive stage of the lesion. The lesion is initially seen as localized subchondral bony flattening with a normal articular surface, an aspect that was observed in our case. In more advanced evolutive stages, the sonographic images observed in the sub-chondral bone of the femoral condyles are sim-ilar to those seen in the capitellum, showing nondisplaced and slightly displaced fragments as double hyperechoic areas in the capitellar subchondral bone. When the fragment has com-pletely separated from the underlying bone, the osteochondral defect is usually observed in the capitellum.7
In this study, the utility of sonography was shown in the diagnosis of OD of the external femoral condyle, in the surgical planning of percutaneous drillings of the lesion, and also in the postoperative follow-up. Treatment of OD lesions in the knee is often a matter of debate and depends on several factors, including the patient’s age and symptoms and the stability, location, and size of the lesion.3Many types of
surgical intervention have been proposed for OD treatment, including transarticular drilling, fixation of the fragment, bone grafting, and frag-ment excision. Its therapy is determined by the stage of the lesion, and MR imaging is the method of choice for staging. The most common sign of unstable OD on MR imaging is a line of high signal intensity between the fragment (OD lesion) and the underlying femur.1,3,8Treatment
is typically nonsurgical for stable lesions and sur-gical for unstable lesions. Staging of OD is of the utmost importance for prognosis and therapy. According to the OD classification system using MR imaging proposed by Bohndorf,1MR
imag-ing stage I (stable OD) is a condition generally treated conservatively, and MR imaging stage II (unstable OD) requires arthroscopy with possi-ble intervention.
Arthroscopy is generally used for the initial sur-gical treatment and can be a diagnostic proce-dure as well as a therapeutic tool. Drilling is still the treatment of choice in early stages of OD. In our case, good results in the OD lesion of the external femoral condyle were obtained by means of sonographically guided percutaneous drillings, and arthroscopy helped in fixation of
the fragment with biodegradable polylactic acid pins. This procedure is safe and simple and can be carried out without arthroscopy. No difficulty was found during the procedure.
In conclusion, this case serves to indicate the utility of sonography for the treatment of OD lesions and for evaluating the progress of frag-ment healing. We think that sonographically guided percutaneous drilling may well be a feasi-ble alternative to arthroscopic percutaneous drilling in early lesions of a knee without frag-ment displacefrag-ment.
References
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