Magnetic resonance imaging comparison of lateral collateral ligament and patellar tendon length

The problem of using patellar tendon auto or allografts for lateral collateral ligament reconstruction results in the occurrence of ligaments mismatch. The length of patellar tendon does not match the lateral collateral ligament.

Out of 151 patients, who formed the study, 102 were men with the mean age of 30 years (18-54) and 49 women, with the mean age of 34 (18-55), and they all underwent magnetic resonance imaging of the knee. Both patellar tendon and lateral collateral ligament were measured using a three-dimensional isovoxel true-fast-imaging with steady-state precession sequence with water excitation and secondary multiplanar reformations. In order to visualize the lateral collateral ligament insertions precisely, sagittal images were reformatted according to the anatomical, oblique ligament position, in anteriorly tilted, paracoronal plane. The length of the patellar tendon was measured from the patellar apex to the tibial tuberosity insertion site.

The mean patellar tendon length was 52.88 +/- 7.56 mm (37-75) with a significant difference between men and women. The mean lateral collateral ligament length was 61.21 +/- 5.77 mm (46-80) with a significant difference between genders. The average differences between lateral collateral ligament and patellar tendon length was 8.38 +/- 7.23 mm (-9 to 26) without a significant difference between the genders. In 18 (11.92%) patients, the patellar tendon was longer than the lateral collateral ligament; in 7 patients (4.63%) they were equal; and in 126 patients (83.44%) the patellar tendon was shorter than the lateral collateral ligament.

The length of patellar tendon does not match the length of lateral collateral ligament. If patellar tendon auto or allograft is used for lateral collateral ligament reconstruction, the lengths of both ligaments must be determined preoperatively in order to avoid intraoperative complications.