Summary

Autograft sources in the knee measured on MRI were found to be smaller in women compared to men, with significant differences in length, width, and diameter, but not thickness.

Abstract

Introduction

ACL reconstruction is one of the most common surgical procedures performed in the United States. Several options of autograft sources are available, such as bone-patellar-tendon-bone (BPTB) and hamstring (HS), as well as quadriceps tendon (QT), which has seen rising interest in the past few years. The importance of graft size in outcomes following ACL reconstruction has been emphasized in recent literature, with data suggesting increased failure rates with graft diameters less than 8mm. Moreover, graft dimension is also associated with intraoperative and postoperative complications, including patellar tendon (PT) rupture after BPTB harvest from a narrow PT, difficulty regaining quadriceps strength, and graft-tunnel mismatch when the PT is too long. Therefore, accurate knowledge of graft dimensions preoperatively is paramount for selecting the most appropriate graft type for each patient. The purpose of this study was to compare the dimensions of the structures most frequently harvested for autograft on MRI between male and female patients, as well as to describe their association with anthropometric measurements.

Methods

An institutional database was used to identify patients who had undergone knee MRI, and those with a history of prior fracture or surgery to the knee joint, presence of osteoarthritis (OA), obvious knee deformity, extensor mechanism abnormalities (such as Osgood-Schlatter’s disease, history of patellar dislocation or subluxation), open physis, ligamentous or tendinous injuries were excluded. Demographic data (age at the time of MRI, sex) and anthropometric data (weight, height, calculated BMI) were collected. Measurements included the length, thickness, and width of the patellar tendon (PT) and patella, the thickness and width of the quadriceps tendon (QT), and the diameter of the hamstring tendons using previously described techniques.

Results

A total of 60 patients were included (30 females and 30 males), with a mean age of 39.6 (16.9), and 31.8 (12.5), respectively. The mean height was 161.7 (7.5) and 178 (8.6) centimeters for women and men. Comparison of all knee MRI measurements between women and men were significantly different, except for PT and QT thickness. Table I summarizes the measurements for each sex and the comparison between them. In women, height was found to have a moderate positive correlation to the patella bone length [r(28)=.47, p=.009], thickness [r(28)=.4, p=.025], and width [r(28)=.45, p=.012]. In men, height was found to have a moderate positive correlation with PT width [r(28)= .5, p=.004]. In males, 97% and 93% had PT and QT widths >24mm to create a minimum 8mm graft, whereas this was true for only 70% and 66% of women (p=0.006, p=0.010).

Discussion And Conclusion

In this MRI-based study, all autograft sources in the knee were found to be smaller in women compared to men, with significant differences in length, width, and diameter, but not thickness. Furthermore, in women, 30% of PT and 34% of QT did not have adequate width to create an 8mm graft. Given the greater risk of ACL failure when grafts are less than 8mm in size, further studies are needed to identify the optimal graft options to minimize donor site morbidity in female patients.