Osteochondral Grafts

P008 - Osteochondritis Dissecans Lesion Location is Highly Concordant with Mechanical Axis Deviation

Corresponding Author
Disclosure
W. Bugbee, JRF Ortho, Consultant
Presentation Topic
Osteochondral Grafts
Poster Rating
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Abstract

Purpose

Osteochondritis dissecans (OCD) is a relatively rare condition typically afflicting younger patients. Although numerous theories have been postulated, including vascular, mechanical, trauma, genetic, and abnormalities of the ossification center, the exact etiology of OCD is unknown. The purposes of the study were: (1) to determine if mechanical axis deviation correlates with OCD lesion location in the knee, (2) to determine whether degree of mechanical axis deviation correlated with size of OCD lesion, and (3) to determine whether the deformity was more commonly in the distal femur or proximal tibia.

Methods and Materials

We identified 61 knees that underwent osteochondral allograft (OCA) transplantation for femoral condyle OCD lesions and had preoperative lower extremity alignment radiographs. Lower extremity mechanical axis, mechanical lateral distal femoral angle (LDFA), and medial proximal tibial angle (MPTA) were measured. Lesion location and area were retrieved from operative records.

Results

Location of the OCD lesion was medial femoral condyle (MFC) for 37 knees and lateral femoral condyle (LFC) for 24 knees (Table 1). Among knees with MFC lesions, alignment was varus in 25 (68%). Conversely, knees with LFC lesions had valgus alignment in 16 (66%). The LFDA was significantly more valgus in the LFC group. MPTA was not different between MFC and LFC groups. There was no significant correlation between degree of mechanical axis deviation and lesion size (Figure 1).

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Conclusion

In this cohort, two-thirds of patients with symptomatic OCD lesions had associated mechanical axis deviation. Lesion location correlated with mechanical axis deviation. Degree of deformity was not correlated with lesion size. Mechanical axis deviation may play a role in OCD pathogenesis. It is unclear if mechanical axis deviation is associated with causation or prognosis of OCD lesions, but surgeons treating OCD should be aware if mechanical axis deviation is present.

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