PATELLOFEMORAL JOINT CARTILAGE RESTORATION WITH PARTICULATED JUVENILE ALLOGRAFT IN PATIENTS UNDER 21 YEARS OLD: POSTOPERATIVE MRI ANALYSIS AND RETURN TO SPORT RATES

Abstract

Background:Patellofemoral joint cartilage defects are difficult to treat due to their unique thickness and topography. Numerous cartilage restoration techniques are available to surgeons treating articular cartilage defects. However, patellofemoral joint restoration historically produces worse outcomes than tibiofemoral joint restoration. One cell-based option is particulated juvenile allograft cartilage (PJAC), though literature regarding the efficacy of this treatment is sparse, especially in patients under the age of 21 years.Hypothesis/ Purpose:The aim of this study is to investigate postoperative outcomes of PJAC for patellofemoral chondral defects using MRI and return to sport rates in this active, high-demand patient population.Methods:Patients at an urban tertiary care musculoskeletal institution who underwent PJAC for patellofemoral joint cartilage restoration were identified through records review. Patients 21 years old or younger with minimum clinical follow-up of 1 year and postoperative MRI at a minimum of 6 months after surgery were included. Cartilage restoration was assessed by MRI using the International Cartilage Repair Society’s standardized system. Sport activity was collected from medical records.Results:Thirty-six knees in 34 patients with a mean age of 16.1 ± 3.1 years old (range 10—21 years old) were analyzed. Mean follow-up was 32.1 months. Defects were located on the patella in 25 knees, and trochlea in 11 knees (Figure 1). There were no bipolar lesions in the cohort. Mean defect size was 2.47 cm2. Twenty-four knees (66.7%) were graded either ‘normal’ or ‘nearly normal’, and 28 knees (77.8%) had greater than 50% of the defect filled on follow-up imaging. Return to sport rates among patients who participated in a sport preoperatively was 100%.Conclusion:Restoration of patellofemoral chondral defects in young patients with particulated juvenile allograft can be performed with satisfactory short-term efficacy, excellent postoperative MRI appearance, and very high rates of return to sport.Tables/Figures:Figure 1.PJAC Surgical Cases. (A) – (C) A patient with recurrent patellofemoral instability (A) Arthroscopic image demonstrating full-thickness defect at inferior portion of patella. (B) Defect bed prepared with vertical walls. (C) PJAC implanted, set and margins sealed with fibrin glue to achieve congruity with adjacent cartilage. (D) — (F) A patient with JOCD (D) Large crater defect of lateral trochlea, friable and easily removed with probe. (E) Approximately 2 x 1.5 cm lesion curetted down to layer of subchondral bone. (F) Initial PJAC placement over bed of fibrin glue. (G) — (I) A patient with recurrent patellofemoral instability. (G) Pre-operative axial T2 MRI demonstrating displaced patella chondral fragment (yellow arrow) and resulting defect (H) Post-operative axial T2 MRI at 1 year demonstrating 75% fill (white arrow). (I) Arthroscopic image of PJAC graft at 18-months post-operative during removal of hardware surgery, demonstrating excellent fill, and some small fraying cartilage, which was gently debrided.