What are These Cysts Doing in My Graft? A Meta-Analysis on Cystic Occurrence After Autografting and Allografting for Osteochondral Lesions of the Talus

BackgroundThe exact incidence of cyst formation after graft transplantation for osteochondral lesions is unknown. The primary purpose was to assess and compare cystic occurrence after autografting, allografting, and osteoperiosteal grafting for osteochondral lesions of the talus. Our secondary aim was to assess the correlation of clinical outcomes with the presence of postoperative cysts.MethodsA literature search was performed up to October 2023 through PubMed, Embase (Ovid), and Cochrane Library. The primary outcome was the postoperative cystic occurrence rate. A random-effects model with moderator analysis was used to calculate differences in occurrence rates between treatment groups. The relationship between the presence of cysts and clinical outcomes was described.ResultsThirteen studies were included with 382 ankles. The average radiological follow-up at which the presence of cystic occurrence was assessed ranged from 12 to 84 months. The rates of cystic occurrence for the osteochondral autograft transplantation group, the allograft transplantation group, and the osteoperiosteal transplantation group were 42% (95% confidence interval [CI] = 24-61), 58% (95% CI = 40-74), and 34% (95% CI = 12-67), respectively, without any significant differences noted. No relationship between the presence of cysts and clinical outcomes was found.ConclusionPostoperative cystic occurrence is common after osteochondral autograft transplantation (42%), allograft transplantation (58%), and osteoperiosteal transplantation (34%) in osteochondral lesions of the talus-without significant intertreatment differences. The postoperative presence of cysts was not correlated with clinical outcomes. Future research should assess whether the postoperative presence of cysts correlates with (clinical) outcomes at longer follow-up.Level of Evidence:Level IV, systematic review and meta-analysis.