OSTEOCHONDRAL ALLOGRAFTING IN THE SKELETALLY IMMATURE KNEE: HIGH RATES OF INCORPORATION AND EXCELLENT EARLY OUTCOMES

BACKGROUND: While an excellent option for osteochondral defects in the adult knee, outcomes following fresh osteochondral allograft (OCA) the skeletally immature are limited. Purpose: To compare radiographic and patient reported outcomes (PROs) in mature and skeletally immature adolescents following OCA of the knee. METHODS: An IRB-approved review of fresh size-matched OCA treatment of knee lesions in patients aged < 19 years within a pediatric sports medicine practice from 1/2006-3/2019 was completed. Following exclusion of patients with less than 12 months follow-up, demographics, lesion characteristics, reoperations, and PROs were evaluated. A novel grading scale (k= 0.832) was utilized to evaluate radiographic OCA incorporation: A=complete, B= >50%, or C= <50% healed. RESULTS: Forty-four patients [15.5 years (9.6-19.8) treated with OCA of the distal femur or patella (LFC= 18, MFC=17, Trochlea=6, Patella=3), 24 with open and 20 with closed physes, with 2.2 year follow up (range 1-5.3 years) were evaluated. Overall average graft size was 4.76cm2 and did not differ significantly between groups. Thirty-nine patients underwent at least one prior procedure to the ipsilateral knee, most frequently for attempted osteochondral lesion healing (77%), followed by realignment (22.7%), and meniscal pathology (15.9%). Graft failure occurred in only one skeletally immature patient with a trochlear lesion. Those with open physes were more likely to demonstrate complete graft incorporation (66.6%, p=0.001). 21(88%) patients with open physes and 17(85%) patients with closed physes had radiographic healing grades of A or B one year post-operatively. There was no difference in healing grade based on graft size, depth, or location within the knee. There was no difference in pre-operative PROs or activity scores. At final follow-up, open physes OCA patients demonstrated better KOOS scores (KOOS daily living 97.0 vs 89.5, p=0.02; KOOS pain 95.7 vs 84.6, p= 0.04; KOOS quality of life 157.2 vs 59.6, p= 0.005). Final activity scores did not vary by skeletal maturity (Pedi-IKDC 75.8 vs 77.99; Pedi-FABS 17.2 vs 13.5,) or radiographic healing grade. Daily living and pain scores were better in those with more radiographic healing (KOOS daily living 98.6 vs 86,2, p= 0.02; KOOS pain 96.7 vs 82.3, p= 0.048). CONCLUSION: Fresh osteochondral allograft treatment in the young knee may be expected to yield good early results. Despite relatively large graft size, when indicated for patients with open physes, equivalent or improved healing and patient reported outcomes may be expected.