Abstract
ObjectivesPatients with recurrent instability after anterior cruciate ligament (ACL) reconstruction often present with enlarged or misplaced tunnels and bone grafting is required prior to the actual revision reconstruction. Autologous bone grafting features limited quantity and donor site morbidity. These problems may be eliminated utilizing cancellous bone allografts, but their efficiency and reliability have not been investigated systematically. The aim of the present study was to compare tunnel filling rates attained by utilizing either allogenic or autologous cancellous bone grafts.Materials and methodsA total of 103 consecutive patients were enrolled retrospectively. All patients suffered from recurrent instability and underwent either allogenic or autologous cancellous bone grafting. Computed tomography (CT) was carried out before and after the bone grafting procedure. Based on preoperative CT scans, positioning and maximum diameter of the femoral and tibial tunnels were determined. Tunnel filling rates were calculated as a ratio of pre- and postoperative tunnel volumes. Primary outcome was the tibial tunnel filling rate. Femoral filling rates and density of the grafted bone were assessed secondarily.ResultsPreoperative CT scans revealed no significant differences between the two groups regarding distribution of misplacement and widening of the femoral or tibial tunnel. Postoperative CT scans were conducted after an interval of 5.2 months. Tunnel filling rates of 74.5% (± 14.3) femoral and 85.3% (± 10.3) tibial were achieved in the allogenic compared to 74.3% (± 15.9) femoral and 84.9% (± 9.4) tibial in the autologous group. With p values of 0.85 at the femur and 0.83 at the tibia, there were no significant differences between the groups. The density of the grafted bone revealed significantly higher values in the allogenic group.ConclusionsUtilizing cancellous bone allografts in two-staged revision ACL surgery provides for sufficient and reproducible filling of enlarged or misplaced tunnels. The filling rates are comparable to those achieved with autologous bone grafting. Advantages of allografts are the unrestricted quantity and the absence of any harvesting procedure.
Highlights
The number of primary anterior cruciate ligament (ACL) reconstructions performed is constantly increasing [1, 2]
The primary goal in revision ACL reconstruction is the sufficient fixation of an appropriate tendon graft in good quality bone and anatomically positioned tunnels
Inclusion criteria were failure of the ACL graft due to traumatic or non-traumatic reason, the existence of Computed tomography (CT) scans before and after the bone grafting procedure as well as the utilization of either allogenic cancellous bone or autologous cancellous bone derived from the patients iliac crest
Summary
The number of primary anterior cruciate ligament (ACL) reconstructions performed is constantly increasing [1, 2]. The cumulative revision probability constitutes between 4.1 and 6.1% within the first 7 years after the ACL reconstruction [6] In distinct subgroups, such as young athletes, the mean risk of failure and reinjury is as high as 23% [7]. The primary goal in revision ACL reconstruction is the sufficient fixation of an appropriate tendon graft in good quality bone and anatomically positioned tunnels. Patients suffering an ACL reconstruction failure often present with misplaced and/or enlarged tunnels. The misplaced tunnels may converge with the revision tunnels drilled anatomically, potentially jeopardizing sufficient tendon graft fixation. Patients featuring misplaced and/or critically widened tunnels often require a two-staged revision. Once sufficient void filling and proper bone graft incorporation are accounted for, the second step procedure comprises the actual revision ACL reconstruction. The harvesting procedure itself features significant disadvantages: it increases the surgical effort, goes along with pain and other morbidities at the harvesting site [20] and the quantity of cancellous bone is limited [21]
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