Does Extracorporeal Shock Wave Therapy Enhance Healing of Osteochondritis Dissecans of the Rabbit Knee?: A Pilot Study

Severe osteochondritis dissecans (OCD) in children and adolescents often necessitates surgical interventions (ie, drilling, excision, or d,bridement). Since extracorporeal shock wave therapy (ESWT) enhances healing of long-bone nonunion fractures, we speculated ESWT would reactivate the healing process in OCD lesions. We asked whether ESWT would enhance articular cartilage quality, bone and cartilage density, and histopathology of osteochondral lesions compared to nontreated controls in an OCD rabbit model. We harvested a 4-mm-diameter plug of the weightbearing osteochondral surface on the medial femoral condyle of each knee in 20 skeletally immature (8-week-old) female rabbits. We placed a piece of acellular collagen-glycosaminoglycan matrix into the cavity and then replaced the plug. Two weeks after surgery, we sedated each rabbit and treated the right knee in a single setting with shock waves: 4000 impulses at 4 Hz and 18 kV. The left knee was a sham control. Ten weeks after surgery, we assessed cartilage morphology of the lesion using a modified Outerbridge Grading System, bone and cartilage density using histologic imaging, bone and cartilage morphology using the histopathology assessment system, and radiographic bone density and union and compared these parameters between ESWT-treated and control knees. Histologically, we observed more mature bone formation and better healing (1.1 versus 3.4) and density of the cartilage (60 versus 49) on the treated side. Radiographically, we noted an increase in bony density (154 versus 138) after ESWT. ESWT accelerated the healing rate and improved cartilage and subchondral bone quality in the OCD rabbit model. This therapeutic modality may be applicable in OCD treatment in the pediatric population. Future research will be necessary to determine whether it may play a role in healing of human osteochondral defects.