Background

The Semitendinosus tendon is one of the most used autografts for anterior cruciate ligament reconstruction (ACLR). However, its size varies and therefore, it is difficult to predict the graft size preoperatively. Previous studies have suggested that the graft size might influences the risk for graft failure and revision surgery. However, there is lack of evidence evaluating the role of graft size as a factor affecting postoperative knee laxity and subjective knee function after primary ACLR.

Purpose

To determine whether anthropometric measurements (height, weight, BMI, sex, age) and pre-injury Tegner activity scale are predictors of the size of the Semitendinosus graft. Furthermore, to investigate whether graft size affects the risk for revision surgery after primary ACLR, postoperative knee laxity and subjective knee function.

Methods

A total of 4,504 patients who underwent primary ACLR with Semitendinosus tendon autograft from 2005 to 2017, at our institution, were included in the study. Data extracted were anthropometric measurements (height, weight, BMI, sex, age), pre-injury Tegner activity score, 6-months postoperative (side-to-side) laxity measured with KT-1000 at 134-N and 1-year subjective knee function measured with Knee injury and Osteoarthritis Outcome Score (KOOS) subscale scores. The graft diameter was measured using cylindrical sizers (0.5-mm accuracy). Correlation coefficients (Pearson r), a stepwise and multiple linear regression analysis were used to determine the relationship between the graft size and anthropometric measurements. Univariate and multivariate logistic regression analyses were used to evaluate gender, age, pre-injury Tegner activity score and graft size as risk factors for revision surgery within 2 years from primary ACLR.

Results

Semitendinosus tendon graft´s size was related positively to height (r = .403, P < .001) and negatively to gender (r = –.403, P = .006). A regression equation was calculated to predict the size of the Semitendinosus tendon graft, which was for the men (4,688 + 0,021 x height) and for the women (4,688-0,309) + 0,021 x height). No association was seen between graft size and risk for revision surgery. Furthermore, there was no correlation between graft size and postoperative laxity and KOOS.

Conclusions

Height and sex are the most important predictors of Semitendinosus tendon size. The size of the graft doesn´t influence the revision rate, the postoperative knee laxity and the KOOS.

Study design: Prospective cohort study (prevalence); Level of evidence 2.