While there is extensive literature on use of allograft versus autograft in anterior cruciate ligament (ACL) reconstruction, there is very limited clinical evidence to guide the surgeon in choice of allograft tissue type.
To assess the revision risk of allograft primary ACL reconstruction and to compare revision risk based on allograft tissue type and characteristics.
Study Design: Cohort study
All primary allograft ACL reconstructions from an academic institution from 2015-2019 with minimum two-year follow-up were included. Exclusion criteria included absent surgical or allograft type data. Demographics, operative details, and subsequent surgical procedures were collected. Allograft details included graft tissue type, all-soft tissue versus bone block, donor age, irradiation duration and intensity, and chemical cleansing process. Revision risk overall and by allograft characteristics were analyzed.
A total of 421 patients were included with a mean age of 39 ± 12 years and a mean BMI of 30 ± 9 kg/m2. Overall revision risk was 3% (11/421) at mean follow-up of 4.9 ± 1.4 years. There was no difference detected in revision risk by allograft tissue type across Achilles (3%, 3/95), bone-patellar tendon-bone (5%, 3/58), tibialis anterior or posterior (3%, 5/164), and semitendinosus (0%, 0/46) (p=0.38). There was no difference detected in revision risk between all-soft tissue versus bone block allograft (soft tissue 2%, 6/286, vs bone block 4%, 5/135; p=0.34). Of grafts with irradiation data, all grafts were irradiated, with levels varying from 1.5-2.7 Mrad and 83% of grafts having levels of <2.0 Mrad. There was no difference detected in revision rate between low-dose irradiation and medium-to-high dose irradiation cohorts (4% vs 6%, p=0.64).
Allograft tissue type, bone block versus all-soft tissue allograft, and sterilization technique had similar low (0-6%) revision rates for primary ACL reconstruction in 421 patients with mean age of 39 years. Surgeons may consider appropriately processed allograft tissue with or without bone block when indicating ACL reconstruction in the masters athlete.