Abstract: Background: Arthroscopic reconstruction of torn ACL using the quadruple hamstring auto-graft has become the gold standard in treating ACL tears due to its robust stiffness & compatibility with contemporary surgical & fixation techniques. Recently, graft diameter has received increased focus as a source of ACLR failure. A higher failure rate for the reconstructed ACL with grafts smaller than 8 mm in diameter have been noted. Preoperative prediction of the sufficiency of the hamstring graft size for ACL reconstruction would be useful in order to plan alternative graft choices & alternative fixation methods to ensure the graft diameter is minimum 8mm. However, currently there is no well documented standard to accurately predict the diameter & length of quadruple hamstring auto-grafts for ACL reconstruction and existing studies present controversial findings.
Materials & Methods: The prospective study consists of 191 patients who had undergone Arthroscopic ACL reconstruction using quadrupled hamstring auto-graft at the Department of Orthopedic Surgery, Manipal Hospital, Bangalore, from January 2011 to May 2015. Several anthropometric preoperative measurements were obtained for each patient including height, weight, BMI, thigh length & thigh circumference. Activity was assessed using the Tegner activity score. A sub-group of patients (44 out of 191), whose MRI of the affected knee was performed in our institute has been included in the study. In these patients, MRI studies were performed using a standardized protocol.
Results: In our study, there is no correlation between weight, thigh circumference, activity level & BMI when correlated for males & females combined. There is a positive correlation with height in both males & females when considered separately. Taller patients tended to have thicker quadrupled hamstring grafts. However, weight, thigh circumference, BMI, activity level & CSA of combined ST+GT did not correlate with graft thicknes. There is a positive correlation with MRI measurement of CSA of combined GT+ST graft thickness when measured combined for both sexes. There is a positive correlation with individual CSA of GT & ST with graft thickness when measured combined for both sexes. The regression equation that allows prediction of graft thickness based on individual MRI measurement of CSA of GT & ST is GRAFT THICKNESS= (0.2105) CSA OF GT+ 6.8684; GRAFT THICKNESS= (0.0973) CSA OF ST + 6.9645
Conclusion: Our study overwhelmingly concludes that height is the most reliable single predictive parameter for graft diameter & length, both for males & females. MRI done by a standardized protocol is an excellent pre-operative predictor of graft size. Thigh length showed a positive correlation with graft diameter in the combined male & female group & in males & females considered separately. Other anthropometric parameters including body weight, BMI & thigh circumference have no predictive value with regard to graft diameter & length. Preoperative activity level failed to demonstrate a positive correlation with graft dimensions & has no predictive value.
