Aim: To determine the quantity and the quality of the bone bridge between the bone tunnels, in both the femoral and tibial side, after double-bundle anterior cruciate ligament (ACL) reconstruction.

Material and methods: Twenty-seven patients undergoing primary double-bundle ACL reconstruction with hamstring tendon autograft were included in this prospective study. Computed tomography (CT) was performed in all patients at a mean of 13 months postoperatively. The amount of the bone bridge between the bone tunnels was measured, in both the femoral and tibial side, on an axial plane at three locations:

at the level of the joint line

In addition, the bone density of the bone bridge was measured in Hounsfield units (HU) in the same locations. Bone density of the anterior tibial cortex lateral femoral condyle, and adjacent cancellous area, and were measured for comparisons.

Results: CT confirmed that the bone bridge was triangular in shape in all cases in both the femoral and tibial side. On the femoral side, at the level of joint line (apex of the bone bridge) the mean thickness of the bone bridge was 1.7 mm, at the mid-portion the mean thickness of the bone bridge was 3.7 mm and at the base of the bone bridge the mean thickness was 7.1 mm. On the tibal side, at the level of joint line (apex of the bone bridge) the mean thickness of the bone bridge was 1.5 mm, at the mid-portion the mean thickness of the bone bridge was 3.2 mm and at the base of the bone bridge the mean thickness was 6.5 mm. Bone density at the mid-portion and at the base of the bone bridge was similar to the cancellous bone for both the femoral and tibial side. However, the bone density of the bone bridge, at the level of the joint line, for the femoral side was 860 HU and this was not statistically significant in comparison to the density of the lateral femoral cortex (960 HU). Similarly, the bone density of the bone bridge, at the level of the joint line, for the tibial side was 885 HU and this was not statistically significant in comparison to the density of the anterior tibial cortex (970 HU).

Conclusions: Our study demonstrated one year after double-bundle ACL reconstruction the thickness of the triangular bone bridge between the bone tunnels is sufficient at the mid-portion and at the base of the triangle but is thin at the level of the joint line. However, the bone bridge at the apex of the triangle is very strong since its density is similar to that of cortical bone. We believe that the “corticalization” of the bone bridge at the level of the joint line on both the femoral and tibial side is important and contributes significantly to avoid communication of the bone tunnels.

In order to evaluate the short- and long-term clinical and radiological results of MIS in TKA, a prospective randomized trial was designed in our department. All patients admitted to the department under the care of one surgeon specializing in Joint Replacement surgery were assigned to participate in the study, signed a concern form, and randomly allocated into two groups. For patients of group A, a TKA was performed using the mini mid-vastus approach; for patients of group B the surgery was performed using a conventional medial parapatellar incision. The Genesis II prosthesis and MIS instrumentation were used for all patients.

Pre and postoperative clinical and radiological data were collected for all patients at regular time intervals (pre, 1st d, 3rd d, 6th d, 3rd w, 6th w, 3rd m, 6th m, 9th m, 1st y, and every year thereafter). Early postoperative pain was also evaluated using a VAS scale and the ability of early SLR was also recorded.

Until now 80 patients (40 MIS, 40 Controls) have entered the study with a follow-up of more than 6 months. In 5 patients (12.5%) of group A the MIS surgery was abandoned in favor of conventional surgery due to technical problems.

Patients in MIS group A had knees with greater range of motion at 3 w, 6 w and 3 months, better function at 3 and 6 months, and less blood loss. In contrast, the same patients experienced greater pain during the first 3 postoperative days. Surgery lasted 16 minutes more on average for the MIS group A. On radiological evaluation technical errors were observed in 5 patients of MIS group A.