Anteversion and length of the femoral tunnel in ACL reconstruction: in-vivo comparison between rigid and flexible instrumentation

Abstract

Background Due to it being tangential to the distal femoral axis, the anteromedial portal presents significant risk of causing iatrogenic damage, and of producing tunnels that are too short for optimal osseointegration. Flexible reamers were developed to eliminate the need for knee hyperflexion and offer better-controlled orientation of the femoral tunnel. We aimed to compare the anteversion and length of femoral tunnels drilled using flexible reamers to those drilled using rigid reamers. Methods Between May 2012 and December 2013, all patients receiving ACL reconstruction performed by one surgeon were operated on using either a rigid or a flexible reamer from the same supplier (Versi-Tomic® system, Stryker, Kalamazoo, Michigan). The height of each patient was recorded, and the length and anteversion of the femoral tunnels were measured intra-operatively and on true lateral radiographs, respectively. Results Thirty-seven patients underwent operations using the rigid instrumentation, and 43 using the flexible instrumentation. There was no statistically significant difference between the two groups in either sex or height ( p = n.s.). The patients operated on using the rigid instrumentation had tunnels anteverted by 18.6° ± 6° and 33.6 ± 2.9 mm long. Those operated on using the flexible instrumentation had tunnels anteverted by 40° ± 2° and 41.1 ± 3.57 mm long. Both anteversion and tunnel length were significantly greater for tunnels drilled using the flexible instrumentation ( p < 0.001). Conclusions This study demonstrated that flexible reamers produce significantly more anteverted and longer femoral tunnels during ACL reconstruction than rigid reamers. Clinical studies remain necessary to assess the outcomes of ACL reconstruction using flexible reamers.

Comparing the Use of Flexible and Rigid Reaming Systems Through an Anteromedial Portal for Femoral Tunnel Creation During Anterior Cruciate Ligament Reconstruction: A Systematic Review

“…Additionally, pins placed via AM-FR were significantly farther from the femoral origin of the LCL (26.1 mm vs 13.4 mm). Kosy et al, 20 Wein et al, 35 Dave et al, 5 Steiner and Smart, 33 and Tashiro et al 34 all found more anterior femoral tunnel exit points with the use of AM-FR compared with AM-RR. Larson et al 21 found no difference with regard to femoral tunnel exit point ( Table 7 ).…”

“…Eight included studies 9 , 15 , 16 , 20 , 21 , 23 , 33 , 35 quantified femoral tunnel positioning by utilizing radiologic parameters. No studies reported any significant difference in the intra-articular femoral tunnel aperture location.…”

“…Additionally, many of the studies directly comparing the use of AM-FR and AM-RR have contained a low level of evidence and differed in the radiographic modality used for assessment. Specifically, several included studies 15 , 23 , 33 , 35 utilized radiographs for evaluation of tunnel positioning and measurement, which may be less accurate than other modalities of advanced imaging (see Table 1 ). Therefore, further study is required to more clearly define the anatomic or radiologic differences that result from the use of these 2 methods.…”

“…15,16,20,36 Table 3 illustrates a comparison of 6 studies that reported femoral tunnel positioning in the frontal, coronal, sagittal, or axial plane. 15,20,21,23,33,35 Two out of 3 studies 15,33,35 reported a significant difference in tunnel positioning in the sagittal plane, with AM-FR resulting in greater tunnel anteversion in these studies (Figure 3). 33,35 One out of 5 studies 15,20,21,23,33 reported a significant difference in tunnel positioning in the frontal or coronal plane, with AM-FR resulting in a less vertically oriented tunnel in this instance (Figure 3).…”

An Analysis of the Femoral Drilling Angle to Avoid Tunnel Collision during Double-Bundle Anterior Cruciate Ligament and Anterolateral Ligament Reconstruction on the Knee

“…Although the outside-in technique, which allows the point of the outlets to be controlled on the femoral lateral surface, may be considered, this technique leads to acute graft bending, which is associated with poor graft maturation. 35 Therefore, for such knees, femoral drilling using the flexible reamer and curved guide system, which allows a certain degree of control over intra-articular tunnel orientation 36 and can produce significantly more anteverted femoral tunnels than those obtained with a rigid drill 37 or other fixation methods such as anchors or staples, may be better.…”