Femoral and tibial graft tunnel parameters after transtibial, anteromedial portal, and outside-in single-bundle anterior cruciate ligament reconstruction.

BACKGROUND: Anatomic graft tunnel placement is recommended in anterior cruciate ligament (ACL) reconstruction to restore knee joint stability and function. Transtibial (TT), anteromedial portal (AMP), and outside-in (OI) retrograde drilling surgical techniques have been described for tibial and femoral bone tunnel preparation. PURPOSE/HYPOTHESIS: The purpose of this study was to evaluate the bone tunnel parameters and compare the ability of 3 different surgical techniques to achieve placement of the ACL femoral and tibial bone tunnels at the center of the native ACL femoral and tibial attachment sites. The hypothesis was that tunnel placement using an AMP or OI technique would result in optimized tunnel parameters and more closely reconstruct the center of the native ACL femoral attachment site. STUDY DESIGN: Cohort study; Level of evidence, 3. METHODS: The study population consisted of 100 patients undergoing anatomic single-bundle ACL reconstruction using multiple-stranded hamstring tendon grafts. In group 1 (n = 36), the femoral tunnel was drilled using a TT surgical technique; in group 2 (n = 32), the femoral tunnel was drilled through an AMP; and in group 3 (n = 32), the femoral tunnel was created by use of an OI technique with retrograde drilling. Computed tomography (CT) scans were obtained postoperatively, and characteristics of femoral and tibial tunnel apertures were correlated to femoral and tibial measurement grid systems. The position of the resulting tibial and femoral bone tunnels for each group was compared with the center of the native ACL attachment sites. RESULTS: There were statistically significant differences (P < .05) for the ACL femoral tunnel between the 3 groups with respect to intercondylar height, total tunnel length, graft fixation length, tunnel axis, and tunnel entry angle. Statistically significant differences (P < .05) were found for the ACL tibial tunnel with respect to anteroposterior tunnel position and sagittal tunnel axis between the TT and both the OI and AMP techniques. The OI surgical technique produced more oblique and anatomically correct femoral tunnel apertures and longer femoral tunnel lengths compared with the AMP technique. Both AMP and OI techniques resulted in a more precise replication of intercondylar tunnel depth and height. There was no statistically significant difference for graft fixation length between the AMP and OI techniques. CONCLUSION: The AMP and OI surgical techniques were superior in positioning the ACL femoral tunnel at the center of the native ACL attachment site compared with the TT technique. An acceptable graft fixation length was obtained for all 3 surgical techniques.

Quantification of tibial bone loss in antegrade versus retrograde tunnel placement for anterior cruciate ligament reconstruction.

PURPOSE: Tibial bone destruction during primary graft tunnel placement and tibial bone loss following tunnel enlargement represent major challenges in revision reconstruction of the anterior cruciate ligament (ACL). Initial all-inside ACL reconstruction facilitates the preparation of tibial bone sockets rather than full tunnels that potentially preserve tibial bone stock. The purpose of this study was to comparatively assess length, diameter and volume of tibial graft tunnels following all-inside and conventional ACL reconstruction. METHODS: Postoperative computed tomography (CT) scans of 59 patients were assessed following ACL reconstruction. In 35 patients we used conventional antegrade tibial tunnel drilling and in 24 all-inside retrograde tibial bone sockets. Imaging analysis included total, minimal and maximal tunnel length and tunnel diameter. Tunnel volumes were calculated corresponding to these parameters. RESULTS: Statistically significant group differences (p < 0.01) could be detected for tibial tunnel volume, length and diameter between conventional antegrade and all-inside retrograde tibial bone tunnels and sockets, respectively. CONCLUSIONS: Compared with conventional techniques, all-inside retrograde drilling of tibial bone sockets is effective in preserving significant bone stock, which might be beneficial for revision reconstruction in cases of eventual primary graft failure.

The predictive effect of anatomic femoral and tibial graft tunnel placement in posterior cruciate ligament reconstruction on functional and radiological outcome.

PURPOSE: Biomechanical reports have advocated anatomic graft tunnel placement for reconstruction of the posterior cruciate ligament (PCL) to restore knee joint stability and facilitate optimal functional outcome. However, in vivo investigations that correlate tunnel position to functional results are lacking so far. This study evaluates the anatomic accuracy of femoral and tibial tunnel apertures on postoperative computed tomography (CT) scans and compares these findings to subjective and objective clinical outcome parameters. METHODS: After single-bundle PCL reconstruction, 29 patients were stratified into several subgroups according to the anatomic accuracy of femoral and tibial tunnel apertures measured on postoperative CT scans. A threshold value for the centres of the tunnel apertures was determined using a measurement grid system as a radiographic reference. To evaluate the functional and radiological results, visual analogue scale, International Knee Documentation Committee (IKDC), Tegner, Lysholm, Knee Injury and Osteoarthritis Outcome Score and osteoarthritis scores were obtained. RESULTS: Comparison between functional outcome and tunnel position yielded a statistically significant difference for subjective IKDC score and angle segment α and for objective stability and tunnel position P3 but no statistically significant difference with respect to intercondylar depth, intercondylar height and tibial tunnel position P2. No correlation was found between anatomic tunnel position and present or progressive osteoarthritis on follow-up. Of the patients, 72 % classified their result as excellent and good and 90 % would repeat surgical treatment. CONCLUSIONS: Despite a small sample size and subject to the threshold values we used, our data indicate a potentially minor effect of anatomic tunnel placement on midterm functional outcome following PCL reconstruction.

In vivo evaluation of femoral and tibial graft tunnel placement following all-inside arthroscopic tibial inlay reconstruction of the posterior cruciate ligament.

BACKGROUND: The arthroscopic all-inside tibial inlay technique represents a novel procedure for posterior cruciate ligament (PCL) reconstruction. However, in vivo investigations that evaluate the accuracy of this technique regarding anatomic graft tunnel placement are few. The objective of this study was to analyse the femoral and tibial tunnel apertures using computed tomography (CT) and compare these findings to recommendations in the literature. METHODS: CT scans were obtained in 45 patients following single-bundle PCL reconstruction. The centres of the tibial and femoral tunnel apertures were correlated to measurement grid systems used as a radiographic reference. RESULTS: The centre of the femoral tunnel aperture was located at 42.9% ± 9.4% of the total intercondylar depth and at 12.9% ± 7.2% of the total intercondylar height. The angle α for the femoral tunnel position was measured at 64.2° ± 10.0°. The centre of the tibial tunnel aperture was found at 51.8% ± 4.1% of the total mediolateral diameter of the tibial plateau. The superoinferior distance of the tibial tunnel aperture to the joint line was 9.6 mm ± 4.4 mm on frontal and 9.3 mm ± 3.4 mm on sagittal 3D-CT scans. The distance of the tibial tunnel aperture to the former physis line averaged to 0.8 mm ± 3.4 mm. Comparison to the corresponding reference values revealed no statistically significant difference. CONCLUSION: Arthroscopic tibial inlay reconstruction is an efficient procedure for precise replication of the anatomical footprint of the PCL. LEVEL OF EVIDENCE: IV, prospective case series.

The effectiveness of skeletal imaging for quality assessment in posterior cruciate ligament reconstruction: reliability and validity of radiographs and computed tomography.

PURPOSE: For intra- and postoperative evaluation of precise and anatomic graft tunnel position, radiographs (XR) and computed tomography (CT) scans have been suggested. The purpose of this study was to evaluate the reliability and validity of XR and CT for quality assessment following PCL reconstruction. METHODS: Postoperative radiographs and CT scans were obtained in 45 consecutive patients following a standard single-bundle PCL reconstruction. Femoral and tibial tunnel apertures were correlated to femoral and tibial measurement grid systems. To assess the reliability and validity of XR and CT scans three independent observers evaluated radiographic and CT images for the position of femoral and tibial tunnel apertures. RESULTS: Almost perfect inter- and intra observer agreement (0.79-0.99) was found for all CT measurements except for the distance of the tunnel position to the previous physis line. Almost perfect and strong inter- and intraobserver agreement (0.70-0.98) was found for all tibial measurements on XR which tended to increase with repeated interpretation and to decrease with low levels of observer qualification. Femoral measurements yielded only poor-to-moderate reliability (0.02-0.5) between raters on XR but strong intraagreement within experienced observers (0.45-0.86). Specificity for XR was calculated with 75.7 % for P2 and P3 and with 71 % for femoral tunnel depth and height. CONCLUSION: XR and CT represent complementary imaging modalities and both offer considerable accuracy and precision for the determination of femoral and tibial tunnel apertures following PCL reconstruction and can be recommended for intra- and postoperative quality assessment.

Skeletal imaging following reconstruction of the posterior cruciate ligament: in vivo comparison of fluoroscopy, radiography, and computed tomography.

OBJECTIVE: Intra- and postoperative validation of anatomic footprint replication in posterior cruciate ligament (PCL) reconstruction can be conducted using fluoroscopy, radiography, or computed tomography (CT) scans. However, effectiveness and exposure to radiation of these imaging modalities are unknown. The objective of this study was to evaluate the comparative effectiveness of fluoroscopy, radiography, and CT in detecting femoral and tibial tunnel positions following an all-inside reconstruction of the PCL ligament in vivo. The study design was a retrospective case series. MATERIALS AND METHODS: Intraoperative fluoroscopic images, postoperative radiographs, and CT scans were obtained in 50 consecutive patients following single-bundle PCL reconstruction. The centers of the tibial and femoral tunnel apertures were identified and correlated to measurement grid systems. The results of fluoroscopic, radiographic, and CT measurements were compared to each other and accumulated radiation dosages were calculated. RESULTS: Comparing the imaging groups, no statistically significant difference could be detected for the reference of the femoral tunnel to the intercondylar depth and height, for the reference of the tibial tunnel to the mediolateral diameter of the tibial plateau and for the superoinferior distance of the tibial tunnel entry to the tibial plateau and to the former physis line. Effective doses resulting from fluoroscopic, radiographic, and CT exposure averaged 2.9 mSv, standard deviation (±SD) 4.1 mSv, to 1.3 ± 0.8 mSv and to 3.6 ± 1.0 mSv, respectively. CONCLUSIONS: Fluoroscopy, radiography, and CT yield approximately equal effectiveness in detecting parameters used for quality validation intra- and postoperatively. An accumulating exposure to radiation must be considered.