Cartilage Injury in the Knee: Assessment and Treatment Options

Aaron J. Krych, MD; Daniel B. F. Saris, MD, PhD; Michael J. Stuart, MD; Brittney Hacken, MD


J Am Acad Orthop Surg. 2020;28(22):914-922. 

In This Article

Particulated Juvenile Allograft Cartilage

Particulated juvenile allograft cartilage (PJAC) involves implantation of immature chondrocytes. Juvenile cartilage is thought to have improved chondrogenic activity as compared to adult cartilage and therefore makes it a suitable option for cartilage restoration procedures.[38] This treatment is most often used for large >2 cm2 grade three or four patellar lesions that have failed nonsurgical treatment. Concurrent pathology such as patellar instability should also be addressed at the time of surgery.

Similar to MACI/ACI, this procedure involves débridement of the lesion to a stable rim and to healthy subchondral bone. Fibrin glue is then laid in the lesion, followed by an even distribution of PJAC and a subsequent layer of fibrin glue (Figure 8). PJAC provides the benefit of ease of contour matching and therefore is a suitable option for patellar chondral lesions. The main advantage of PJAC is that it is a one stage procedure, unlike the two stage surgery required for MACI/ACI.[38,39]

Figure 8.

Photographs showing the particulated juvenile allograft cartilage. A, Particulated juvenile allograft cartilage evenly filling the defect on a bed of fibril glue. B, An additional layer of fibril glue is applied over the cartilage sealing it in place.

Studies have shown symptomatic improvement in patients with patellar chondral lesions at the short-term follow-up after this procedure, but no randomized controlled studies have been performed comparing the outcomes of PJAC with other cartilage procedures in the knee. A common complication similar to MACI/ACI is graft hypertrophy.[38,39] Most research on PJAC has been focused on talus lesions in the ankle, and therefore, further studies are needed comparing PJAC with other common cartilage restoration procedures in the knee.