Penetrating Blast Injury to the Knee of a United States Soldier Treated with Allograft Mosaicplasty

OBJECTIVE: This is the first report of successful allograft mosaicplasty treatment of a large osteochondral lesion of the knee caused by a blast fragment sustained during combat operations. The patient was able to return to active duty following rehabilitation. METHODS: An active-duty infantryman sustained an osteochondral lesion of the medial femoral condyle caused by a metallic fragment of an explosively formed projectile. Initial treatment consisted of removal of the foreign body and primary closure. The patient continued to experience pain, mechanical symptoms, and repeated effusions after initial nonoperative treatment. Allograft mosaicplasty of the lesion utilizing two 18-mm-diameter fresh allograft osteochondral plugs was performed at 6 months post-injury. RESULTS: At 2-year follow-up, the patient remains on active duty with marked improvement in symptoms. Two years postoperatively, his outcome scores are 72 of 100 on the Western Ontario and McMaster University osteoarthritis scoring index (WOMAC) and 60 of 100 on the Knee Injury and Osteoarthritis Outcome Score (KOOS). His follow-up x-rays and MRI demonstrate intact articular cartilage and subchondral bone incorporation. CONCLUSION: Penetrating injuries to joints are commonplace in the battlefield environment. Combat injuries to the knee are frequently associated with articular cartilage injury. While numerous cartilage restoration techniques have been used with success for the treatment of osteochondral injuries to the femoral condyles, no published reports describe the use of allograft mosaicplasty in this location for open, penetrating injuries with focal cartilage loss. This is the first documented use of allograft mosaicplasty for a traumatic osteochondral defect of the medial femoral condyle caused by a metallic projectile. The patient was able to return to active duty following rehabilitation. We demonstrate a high level of functioning is possible following allograft mosaicplasty of a large osteochondral lesion caused by penetrating ballistic trauma.