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Role of Allografts in Repairing Chondral Defects of the Knee:

- Discussion:
    - see allograft menu and ocd menu;
    - indicated for larger chondral or osteochondral defects (larger than 2 cm);
    - donor characteristics:
           - donors should be less than 30 years of age, with the graft harvesting the intact knee within 24 hrs of death;
           - knee should be stored in RL at 4 deg;
    - effect of storage and time:
           - references:
                 - Prolonged Storage Effects on the Articular Cartilage of Fresh Human Osteochondral Allografts.
                 - The Effects of Storage on Fresh Human Osteochondral Allografts
                 - Analysis of Stored Osteochondral Allografts at the Time of Surgical Implantation.
                 - Transplantation of Osteochondral Allografts After Cold Storage. 
                 - Cell Viability and Protein Composition in Cryopreserved Cartilage.
                 - Fluorescent Viability Stains Overestimate Chondrocyte Viability in Osteoarticular Allografts
                 - Material properties of fresh cold-stored allografts for osteochondral defects at 1 year.
                 - Enhancing osteochondral allograft viability: effects of storage media composition
                 - Chondrocyte apoptosis: implications for osteochondral allograft transplantation.

 - Outcome Studies:
    - in the study by Ghazavi MT, et al (1997), there was an 85% success rate at 7.5 years;
           - in cases of damaged tibial plateau and meniscus, donor knee tibial plateau can be transfered along w/ its attached meniscus (sutured to the knee capsule);
           - in cases where gross malalignment of the knee was present, osteotomy was performed (HTO or DFO);
           - factors prognostic for poor results include age over 50, malalignment of the knee, workers compensation, and bipolar chondral injuries;
           - these authors noted viability of cartilage cells retrieved even after 12 years;
           - bone healing and incorporation takes place by 6 months, and bone replacement takes place afte one year;
    - in the report by Aubin PP, et al, fresh osteochondral allografts were used to repair articular defects in the distal femur in 72 patients;
           - 60 patients were available for long-term followup (mean, 10 years) to determine graft survivorship and patient outcomes using a modified Hospital for Special Surgery score;
           - 12 of 60 grafts have failed with three having graft removal alone and 9 being converted to total knee replacement;
           - Kaplan-Meier survivorship analysis showed 85% graft survival at 10 years and 74% survival at 15 years;
           - patients with surviving grafts had good function, with a mean HHS score of 83 points at 10 years followup;
           - 10 patients (17%) required meniscal transplantation whereas 41 (68%) required realignment osteotomy done simultaneously with the osteochondral allograft;
           - patients requiring meniscal transplantation, limb realignment, or both, had equally good outcomes at 10 years as those who underwent osteochondral transplantation alone;
           - transplantation to the medial or the lateral condyle had no bearing on long-term outcomes;
           - radiographs were available for 38 patients.
                   - these radiographs showed that 18 (48%) patients had no or mild arthritis, 10 (26%) had moderate, and 10 (26%) had severe arthritis.
    - references:
           - The viability of articular cartilage in fresh osteochondral allografts after clinical transplantation.
           - The fate of articular cartilage after transplantation of fresh and cryopreserved tissue-antigen-matched and mismatched osteochondral allografts in dogs.
           - Fresh osteochondral allografts for post-traumatic defects in the knee. A survivorship analysis. 
           - Resurfacing of the knee with fresh osteochondral allograft.
           - The immune response to osteochondral allografts in dogs.
           - Treatment of osteochondral defects of the distal femur with fresh osteochondral allografts: a preliminary report. 
           - Fresh osteochondral allografts for treatment of articular defects in osteochondritis dissecans of the lateral femoral condyle in adults. 
           - Fresh osteochondral allografts for post-traumatic osteochondral defects of the knee. 
           - Effect of tissue culture storage on the in vivo survival of canine osteochondral allografts.  
           - Long-Term Followup of Fresh Femoral Osteochondral Allografts for Posttraumatic Knee Defects

Isolated chondral fractures of the knee.

Characteristics of the Immediate Postoperative Blood Clot Formation in the Knee Joint

The biological effect of continuous passive motion on the healing of full-thickness defects in articular cartilage:  An experimental investigation in the rabbit

Mesenchymal Cell-Based Repair of Large Full Thickness Defects in Articluar Cartilage

Restoration of injured or degenerated articular cartilage

Spontaneous repair of superficial defects in articular cartilage in a fetal lamb model

Fresh Stored Allografts for the Treatment of Osteochondral Defects of the Knee. 

Unicondylar Osteoarticular Allografts of the Knee