Bioabsorbable screws, whatever the composition, can result in symptomatic intra-osseous tibial tunnel cysts after ACL reconstruction

PurposeTo describe the clinical results of patients who underwent surgical treatment for a intra-osseous tibial tunnel cyst on a bioabsorbable interference screw following anterior cruciate ligament reconstruction (ACL).MethodsThis retrospective study included all patients who underwent surgery between 2004 and 2016 for an intra-osseous tibial tunnel cyst on bioabsorbable interference screw following ACL reconstruction. The diagnosis was suggested clinically by pretibial pain at the incision site, sometimes associated with a palpable subcutaneous nodule and then confirmed on MRI. The first stage of surgery included exploratory arthroscopy followed by open excision/curettage of the cyst and then the tunnel was filled. The main criterion for outcome was a clinically normal knee (no pain, 0-120 range of motion, stable, with no effusion) at 6 months of follow-up.ResultsThis series included 53 patients, mean age 35.39.9years old w ith a mean 4.63.1years (between 3.1months and 19years) of follow-up after ligament reconstruction. The tibial screw was completely absorbed in 9/53 (17%) of patients, and fragmented in 22/53 (41.5%). At the 6-month follow-up, 42/53 (79.2%) patients had a normal knee, 11/53 (20.8%) persistent pain in the cyst area, 52/53 (98.1%) normal range of motion and 53 (100%) a stable knee. A recurrent cyst developed at 2years of follow-up in one patient.Conclusion p id=Par4 Complete absorption of a bioabsorbable interference screw is long, increasing the risk of developing intra-osseous tibial cysts during this period. The development of new materials with improved absorption properties is needed.Level of evidence p id=Par5 IVRetrospective study.