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Background: Nonanatomic transtibial single-bundle anterior cruciate ligament reconstruction (SB-ACLR) with a bone–patellar tendon–bone (BPTB) allograft has been used for a long time and has shown the same satisfactory clinical results as an autograft; however, it has not been reported if a double-bundle ACLR (DB-ACLR) could be performed with a BPTB allograft and achieve even better results.

Hypothesis: The DB-ACLR with a BPTB allograft is technically feasible and will be superior to the SB technique in restoring better anterior and rotating stability.

Study Design: Cohort study; Level of evidence, 2.

Methods: The study was performed with 56 patients, and 52 (25 in the DB group and 27 in the SB group) of them were followed up at 2 to 5 years. With an irradiated deep-frozen BPTB allograft, a standard single-incision arthroscopic technique was used, and the graft was fixed with bioabsorbable interference screws on both the femoral and tibial sides. Outcome assessment at final follow-up included International Knee Documentation Committee (IKDC), Tegner, and Lysholm scores; side-to-side difference by conventional KT-2000 arthrometer; total anteroposterior (AP) laxity by the back-pushing KT-2000 arthrometer; pivot shift (0, +, ++); range of motion (ROM); and isokinetic muscle strength evaluation.

Results: Mean follow-up was 47.3 ± 11.5 and 58.2 ± 6.6 months for the DB group and SB group, respectively. A statistically significant difference in favor of the DB group was found with the total AP laxity at 30° (P < .05). The overall incidence of pivot shift in the DB group (4% ++) was significantly lower than that in the SB group (26%: 19% + and 7% ++; P = .029). No significant differences were found between the 2 groups in terms of IKDC score, Lysholm score, Tegner score, conventional KT-2000 arthrometer anterior laxity, ROM, and muscle strength.

Conclusion: A DB-ACLR with a BPTB allograft is feasible and achieved more satisfactory results than the transtibial SB technique in terms of total AP stability and rotational stability in spite of no significant differences among other clinical parameters.

Background: Tunnels created for reconstruction of a torn anterior cruciate ligament (ACL) are critical determinants of joint stability and clinical outcomes. There is limited objective evidence on the ability of transtibial (TT), anteromedial (AM) portal, and outside-in (OI) operative techniques in creating anatomic tunnels.

Hypothesis: (1) Tibial tunnel–independent techniques can create tunnels more accurately at the anatomic ACL footprint center than the TT technique, and (2) femoral tunnel exit location of the OI and TT techniques on the lateral cortex will be significantly further away from the lateral epicondyle than the femoral tunnel exit location of the AM portal technique.

Study Design: Controlled laboratory study.

Methods: Eight cadaveric knee specimens with a mean age of 56 years were used in this study. A digitizing system was used to record points along the outlines of the ACL insertion area and apertures of tunnels created by the TT, AM portal, and OI techniques. The following parameters were measured from the digitized points: (1) amount of ACL, anteromedial bundle, and posterolateral bundle coverage by the tunnels; (2) relationship between the centers of the ACL and the tunnels; and (3) distance between the center of the femoral tunnel exit and the lateral epicondyle. All the recorded parameters were analyzed in 3-dimensional solid modeling software.

Results: The percentage of ACL footprint coverage achieved by all 3 surgical techniques was not significantly different from one another. However, larger femoral posterolateral bundle coverage was observed in tunnels created by the AM portal and OI techniques than in the TT tunnel. In terms of anteromedial bundle coverage, no significant differences were observed between the 3 techniques. On average, 27.1% ± 17.4% of the TT tunnel was outside the ACL footprint. This was significantly larger compared with 13.6% ± 15.7% with the AM portal technique (P = .01) and 10.8% ± 10.8% in the OI technique (P = .01). Centers of femoral tunnels created by the TT, AM portal, and OI techniques were located at a distance of 3.0 ± 1.5 mm, 2.1 ± 0.9 mm, and 1.5 ± 1.2 mm, respectively, from the ACL footprint center. The femoral tunnel exit location of the AM portal technique on the lateral femoral cortex was closer to the lateral epicondyle than the femoral tunnel exit location of the OI and TT techniques.

Conclusion: Findings of this study indicate that a larger posterolateral bundle coverage is achieved by the AM portal and OI techniques than by the TT technique. Centers of the tunnels created by the AM portal and OI techniques were closer to the native ACL footprint center than the center of the TT technique tunnel. The incidence of a posterior femoral tunnel exit relative to the lateral epicondyle is higher in the AM portal technique than in the OI and TT techniques.

Clinical Relevance: For ACL reconstruction using soft tissue grafts, tibial tunnel–independent techniques can produce more anatomic tunnels than the TT technique.

Background: It has been suggested that a surgeon’s experience and training are the most important factors associated with graft selection, but no studies have qualified this association. Graft usage prevalence has not been described for large anterior cruciate ligament reconstruction (ACLR) populations in the United States.

Purpose: To describe the prevalence of graft usage in a large community-based practice and evaluate the association of patient, surgeon, and site characteristics with choice of primary ACLR graft.

Study Design: Cross-sectional study; Level of evidence, 3.

Methods: Primary ACLRs performed between February 2005 and June 2010 were selected for the study. A community-based ligament registry was used to identify cases and variables used for analysis. Graft choice (any allograft, hamstring autograft, and bone–patellar tendon–bone [BPTB] autograft) was compared by patient characteristics and surgeon and site characteristics. Associations between independent variables and graft choice were evaluated using a polychotomous regression model.

Results: Of the 9849 patients included in the study, 64% were male, and overall median age was 28 years. Of these, 2796 (28.4%) received BPTB autografts, 3013 (30.6%) received hamstring autografts, and 4040 (41.0%) received allografts. The prevalence of graft source by patients’ gender, race, age, body mass index (BMI), as well as surgeons’ fellowship training status, average volume, and site volume were significantly different (all P < .001). Adjusted models showed that patients’ gender (P < .001), race (P = .018), age (P < .001), BMI (P < .001), as well as surgeons’ fellowship training status (P < .001), average volume (P < .001), and site volume (P < .001) are associated with graft selection. Older and female patients with lower BMI were more likely to receive allografts and hamstring autografts than BPTB autografts. Cases performed by non–fellowship-trained surgeons, lower volume sites, and/or lower volume surgeons were also more likely to be performed with allografts or hamstring autografts than BPTB autografts.

Conclusion: Gender, age, race, as well as facility and surgeon characteristics such as volume and location are associated with ACL graft choices.

Background:

The native anterior cruciate ligament (ACL) does not behave as a simple bundle of fibers with constant tension but as a continuum of ligament fibers with differential length change during knee flexion/extension. Computer-assisted navigation can be used to assess length change in different fibers within the native ACL and to evaluate how different reconstruction grafts replicate the range of native ligament fiber length change behavior.

Hypothesis:

Anterior cruciate ligament reconstruction graft size and configuration (single-vs double-bundle) are deciding factors as to how much of the native ACL fiber length change behavior is replicated.

Study Design:

Controlled laboratory study.

Methods:

The fiber length change behavior of the entire native ACL was assessed by measuring the length change pattern of representative anteromedial (AM) and posterolateral (PL) bundle fibers (1 at the center and 4 at the periphery of each bundle). The tibial and femoral ACL attachment areas in 5 fresh-frozen cadaveric knees were digitized, and the length change of each representative fiber was recorded during knee flexion/extension using an image-free, optical navigation system. Subsequently, single-bundle ACL reconstructions of different diameters (6, 9, and 12 mm) positioned at the center of the overall native femoral and tibial attachment sites were modeled to assess how much of the range of ligament fiber length change of the native ligament was captured. This was compared with a double-bundle graft using 6-mm-diameter AM and PL grafts positioned at the centers of the femoral and tibial attachment sites of each separate bundle.

Results:

The 6-, 9-, and 12-mm single-bundle grafts simulated 32%, 51%, and 66% of the ligament fiber length change behavior of the native ACL, respectively. The length change patterns in these grafts were similar to the central fibers of the native ACL: the PL fibers of the AM bundle and AM fibers of the PL bundle. However, even a 12-mm graft did not represent the most AM and PL native fibers. The 6-mm AM and PL bundle grafts (equivalent in cross-sectional area to a 9-mm single-bundle graft) simulated 71% of the native ACL and better captured the extremes of the range of native ligament fiber length change.

Conclusion:

Increasing single-bundle graft size appears to capture more of the range of native ACL fiber length change. However, for a similar graft cross-sectional area, a 2-bundle graft simulates the length change behavior of the native ligament more precisely and thus may better emulate the synergistic actions of anisometric and isometric fibers of the native ligament in restraining knee laxity throughout the range of flexion.

Clinical Relevance:

The range of native ACL fiber length change behavior is better replicated by larger diameter grafts but may be best reproduced by double-bundle reconstruction.

Background: There is no consensus about flexion angle of the knee at the time of graft fixation in anterior cruciate ligament reconstruction.

Purpose: To evaluate the effect of flexion angle at the final graft fixation on the positional relationship as well as the load between femur and tibia.

Study Design: Controlled laboratory study.

Methods: Six intact cadaveric knees were passively flexed and extended under 6 degrees of freedom with the robotic system developed in our laboratory, while their 3-dimensional paths were recorded. Anterior cruciate ligament reconstruction was performed with a single-socket technique using autogenous quadrupled hamstring tendons, while the graft was fixed at 0° (group A), 20° (group B), or 90° (group C) with a constant initial tension of 44 N. The knees then repeated the same movement as before while the relative position between femur and tibia was recorded. The load in the femorotibial joint was also calculated based on the principle of superposition.

Results: Posterior displacement of the tibia compared with the normal knee was the smallest in group B at all flexion angles, while the load between tibia and femur in group B was also the smallest and the closest to the normal knee.

Conclusion: As the positional relationship as well as the load between femur and tibia in group B was the closest to that in the normal knee, 20° of flexion is the most desirable of the positions tested for graft tensioning and fixation at the time of anterior cruciate ligament reconstruction.

Clinical Relevance: The tibia-femur position is well retained when the graft was fixed at 20° of flexion in anterior cruciate ligament reconstruction.

Background: There is controversy regarding the necessity of reconstructing both the posterolateral and anteromedial bundles of the anterior cruciate ligament.

Hypothesis: A laterally oriented transtibial drilled femoral tunnel replaces portions of the femoral footprints of the anteromedial and posterolateral bundles of the anterior cruciate ligament.

Study Design: Descriptive laboratory study.

Methods: Footprints of the anteromedial and posterolateral bundles of the anterior cruciate ligament were preserved on 7 matched pairs (5 female, 2 male) of fresh-frozen human cadaveric femurs (14 femurs total). Each femur was anatomically oriented and secured in a custom size–appropriate, side-matched replica tibia model to simulate transtibial retrograde drilling of a 10-mm femoral tunnel in each specimen. The relationship of the tunnel relative to footprints of both bundles of the anterior cruciate ligament was recorded using a Microscribe MX digitizer. The angle of the femoral tunnel relative to the vertical 12-o’clock position was recorded for all 14 specimens; only 10 specimens were used for footprint measurements.

Results: On average, the 10-mm femoral tunnel overlapped 50% of the anteromedial bundle (range, 2%–83%) and 51% of the posterolateral bundle (range, 16%–97%). The footprint of the anteromedial bundle occupied 32% (range, 3%–49%) of the area of the tunnel; the footprint of the posterolateral bundle contributed 26% (range, 7%–41%). The remainder of the area of the 10-mm tunnel did not overlap with the anterior cruciate ligament footprint. The mean absolute angle of the femoral tunnel as measured directly on the specimen was 48° (range, 42° –53° ) from vertical, corresponding to approximately a 10:30 clock face position on a right knee.

Conclusion: Anterior cruciate ligament reconstruction using a laterally oriented transtibial drilled femoral tunnel incorporates portions of the anteromedial and posterolateral bundle origins of the native anterior cruciate ligament.

Clinical Relevance: A laterally oriented transtibial drilled femoral tunnel placed at the 10:30 position (1:30 for left knees) reconstructs portions of the anteromedial and posterolateral bundles of the anterior cruciate ligament.

Background

The best means of ensuring knee stability after anterior cruciate ligament (ACL) reconstruction remains a core debate in sports medicine.

Hypothesis

There is no difference between ACL reconstruction with patellar tendon or hamstring tendon autografts with regard to postoperative knee laxity and instability.

Study Design

Meta-analysis of individual patient data.

Methods

Pooled analysis of individual patient data from 6 published randomized clinical trials included 423 patients with symptomatic unilateral anterior cruciate ligament injury randomly assigned to reconstruction with patellar tendon or hamstring tendon autograft. Knee instability, defined as a positive pivot-shift test result, was the primary outcome, and knee laxity, defined as a positive Lachman test result, was the secondary outcome. Odds ratios were computed before and after adjustment for potential confounders and trial effect. Regression analyses were performed to look for effects of covariates on outcomes, and mixed-effects models were used to account for a trial effect. Sensitivity analyses were conducted to explore the effects of missing data and excluding each trial.

Results

Anterior cruciate ligament reconstruction with patellar tendon autograft was significantly associated with a decreased risk of a positive pivot-shift test result (adjusted odds ratio, 0.46; 95% confidence interval, 0.24–0.86; P = .016). The risk of having a positive Lachman test result was not significantly different between the 2 groups. The estimated treatment effect was not substantially changed by differences in handling missing data or exclusion of any of the trials. A positive pivot-shift test result was more common in female (P = .003) and younger patients (P = .017).

Conclusion

Postoperative knee instability was less common after ACL reconstruction with patellar tendon autograft than with hamstring tendon autograft.

Background: A more oblique placement of the anterior cruciate ligament (ACL) graft has been related to better control of rotatory knee stability. Femoral fixation with a transverse system might injure its posterolateral structures.

Hypothesis: A cross-pin system, originally developed for transtibial reconstruction of the ACL, can safely be used when creating a lower femoral tunnel through the anteromedial portal. However, a long femoral tunnel must be created to protect the posterolateral structures of the knee.

Study Design: Controlled laboratory study.

Methods: An ACL was arthroscopically reconstructed with a hamstring graft in 22 fresh cadaveric knees. The femoral tunnel was anatomically drilled in all cases. Knee flexion angle was set at 110°. Femoral fixation was performed with a cross-pin system. A 30-mm-long femoral tunnel was created in 11 knees (group A). In the remaining 11 knees, the femoral tunnel was drilled as long as each lateral condyle permitted (group B). For both groups, the relationships were compared between the cross-pin and the lateral collateral ligament (LCL), popliteus tendon, articular cartilage, and peroneal nerve.

Results: In 5 cases of group A, the cross-pin was placed either through the LCL or between the LCL and popliteus tendon, whereas in group B it was always posterior to the LCL (P = .035). The cross-pin was closer to the articular cartilage in group A than in group B (7.14 mm versus 16.9 mm; P < .001). The minimal distance to the peroneal nerve in all specimens was 23.89 mm.

Conclusion: Hamstring graft fixation with a cross-pin system from the anteromedial portal with a 30-mm femoral tunnel presents a higher risk of injury to the LCL. The femoral tunnel should be drilled as long as possible.

Clinical Relevance: A long femoral tunnel is required for safe transverse femoral fixation in an anatomical ACL reconstruction.

Background: Anterior cruciate ligament reconstruction employing transtibial tunnel techniques may result in less than ideal femoral and tibial vertical graft placement, with a residual pivot shift and instability symptoms.

Hypothesis: Nonanatomical graft placement is highly prevalent among knees with failed primary and revision anterior cruciate ligament grafts.

Study Design: Case series; Level of evidence, 4.

Methods: A total of 122 consecutive patients presented to the authors’ center with a failed anterior cruciate ligament reconstruction. Radiographs, magnetic resonance imaging, and operative reports were used to define graft placement. Arthroscopic confirmation of graft placement was obtained in 92 knees during subsequent revision surgery. A nonanatomical graft placement was assigned when ≥50% of the graft was outside of the native tibial and femoral insertions. All patients prospectively completed Cincinnati Knee Rating System questionnaires.

Results: A nonanatomical graft placement occurred in 107 of 122 (88%) knees; 61% of the grafts were entirely on the intercondylar femoral roof, and 35% extended posterior to the anterior cruciate ligament tibial attachment. A transtibial technique had been used in 83%. The mean values for the coronal and sagittal graft placement showed a significantly increased vertical orientation in comparison with a control group (P < .01). Forty-two of the 107 nonanatomical grafts had undergone 1 or more revisions without correction of the misplaced graft tunnels, and these subsequently failed.

Conclusion: The occurrence of nonanatomical graft placement in primary and revision knees may represent an inadequacy of transtibial tunnel drilling techniques to obtain graft placement within the native femoral and tibial footprints. In revision cases, the prior graft location requires close scrutiny so the new graft tunnels are placed at the native anterior cruciate ligament attachments. Independent drilling of tibial and femoral tunnels is recommended using either 2-incision or anteromedial portal techniques.