Do localization and appeareance of bone bruise influence the subjective short-term outcome after ACL reconstruction?

Aims and Objectives: Large external forces in anterior cruciate ligament (ACL) injury mechanisms cause a traumatic impact between femur and tibia. Apart from concomitant intraarticular injuries like meniscal tears and chondral lesions, MRI shows a high prevalence of femorotibial bone bruise (BB) without the arthroscopic proof of macroscopic chondral defects. In recent literature, controversial results are described concerning the association between BB and subjective outcome after ACL injury. There is very limited data for the results following ACL reconstruction. Aim of this study is the evaluation of the influence of localization and appeareance of BB in isolated ACL injuries on the subjective outcome of ACL reconstruction within the first year after surgery. Materials and Methods: This study is an analysis of preoperative MRI and prospectively collected subjective functional scores in 55 patients (sex m:f = 38:17; age 33,71±11,46 years; BMI 26,08±3,44) with isolated ACL injuries without concomitant intraarticular pathologies. These patients were treated between 09/15 and 11/17 by arthroscopic ACL reconstruction with ipsilateral hamstrings. MRI evaluation was performed blinded and independently by a radiologist and a surgeon. BB was diffentiated by 8 localizations: medial/lateral femoral condyle und tibial plateau, anteriorly and posteriorly each (MFA, MFP, LFA, LFP, MTA, MTP, LTA, LTP). Classification of appeareance was done according to Costa-Paz et al. (type I-III). Demographic data and injury mechanisms were collected. Finally, localization and appeareance of BB were analyzed statistically with regard to an impact on subjective functional outcome measures - Lysholm Score (LS) and Tegner Activitiy Scale (TAS) - before surgery (t0) and at four follow-up examinations (t1-t4 within one year after ACL reconstruction. Results: The time between injury and MRI was 35,09±94,52 days, between injury and surgery 96,09±120,75 days. In 80% (n=44) non-contact injury mechanisms could be detected, sports injuries in most cases (60%). BB was found in 94,4% (n=51), the most frequent localizations were LTP (74,5%, n=41) and LFA (56,4%, n=31). A singular femoral BB could not be found. Concerning the appeareance, distribution was shown as followed: n=18 (32,7%) type I, n=26 (47,3%) type II, n=7 (12,7%) type III. In n=6 MRI revealed a depression of the lateral femoral condyle (“lateral femoral notch sign”). For the whole cohort (independently from BB) we could demonstrate a highly significant improvement for LS and TAS over time (t0/t1-t4; ANOVA, p<0,001). Neither localization nor appeareance of BB had a significant impact on LS or TAS for t0-t4. Conclusion: In conclusion, the results of the existing literature for incidence and distribution of BB in ACL injuries are confirmed. Our own data showed no influence of BB on the subjective short-term outcome following ACL reconstruction within the first year after surgery. Further studies with longer follow-up period (>2 years) and volumetric BB measurement are in preparation.