Patient age as a preoperative factor associated with tunnel enlargement following double-bundle anterior cruciate ligament reconstruction using hamstring tendon autografts

Lateral posterior tibial slope and length of the tendon within the tibial tunnel are independent factors to predict tibial tunnel widening following anatomic anterior cruciate ligament reconstruction

PURPOSE

This study aimed to conduct a multivariate analysis to identify independent factors that predict tibial tunnel widening (TW) after anatomical anterior cruciate ligament (ACL) reconstruction using bone-patellar tendon-bone (BPTB) grafts.

METHODS

In total, 103 patients who underwent ACL reconstructions using BPTB grafts were included. Tunnel aperture area was measured using three-dimensional computed tomography 1 week and 1 year postoperatively, and the tibial TW was calculated. The patients were divided into group S comprising 58 patients who had tibial TW < 30% and group L comprising 45 patients who had tibial TW > 30%, retrospectively. Using univariate analyses, age, gender, body mass index, Tegner activity scale, the time between injury and surgery, tibial tunnel location, tibial tunnel angle, medial posterior tibial slope, lateral posterior tibial slope, and length of the tendon in the tibial tunnel were compared between two groups. Multivariate regression analysis was conducted to reveal the independent risk factors for the tibial TW among preoperative demographic factors and radiographic parameters that correlated with the tibial TW in the univariate analyses.

RESULTS

Compared with those at 1 week postoperatively, mean tibial tunnel aperture areas were increased by 30.3% ± 26.8% when measured at 1 year postoperatively. The lateral posterior tibial slope was significantly larger (p < 0.001), and the length of the tendon within the tibial tunnel was significantly longer in group L than that in group S (p = 0.03) in the univariate analyses. Multivariate regression analysis showed that the increase in lateral posterior tibial slope (p = 0.001) and the length of the tendon within the tibial tunnel (p = 0.03) were predictors of the tibial TW.

CONCLUSIONS

This study showed that increased lateral posterior tibial slope and a longer tendinous portion within the tibial tunnel were independent factors that predicted the tibial TW following anatomical ACL reconstruction with a BPTB graft.

LEVEL OF EVIDENCE

III.

Inferior graft maturity in the PL bundle after autograft hamstring double-bundle ACL reconstruction

PURPOSE

The purpose of this study was to evaluate the signal/noise quotient (SNQ) for graft maturation and the serial changes observed in the magnetic resonance imaging (MRI) findings after double-bundle (DB) anterior cruciate ligament (ACL) reconstruction using a hamstring tendon autograft at a minimum of 5 years after surgery.

METHODS

Forty-five patients who underwent DB ACL reconstruction between 2007 and 2010 were included in this prospective study. All participants underwent postoperative MRI at 3 weeks and 3, 6, 9 and 12, 18, 24, 36, 48 and 50 months. The signal intensity (SI) characteristics of the reconstructed graft were evaluated on oblique axial proton density-weighted MR imaging (PDWI) perpendicular to the grafts. The signal/noise quotient (SNQ) was calculated to quantitatively determine the normalized SI. The SNQ of the AMB and PLB was evaluated separately.

RESULTS

The mean SNQ of the AM bundle (AMB) continued to increase until 6 months after surgery (5.2 ± 1.2), and then gradually decreased and became well stabilized by 18 months (3.3 ± 0.5), after which it remained unchanged. On the other hand, the mean SNQ of the PL bundle (PLB) continued to increase until 9 months after surgery (6.2 ± 1.1), and then decreased incrementally and became well stabilized by 24 months (4.1 ± 0.5). The SI of PLB was significantly higher than that of AMB between 3 and 24 months (p = 0.04, 0.03, 0.01, 0.04, 0.02 and 0.03, respectively).

CONCLUSIONS

These results indicate that at least 18 months is needed after ACL reconstruction to sufficiently restore the SI of the AMB, while at least 24 months are needed to for the PLB. The SI of the PLB was significantly higher than that of the AMB at 3-24 months after surgery, indicating that the PLB showed inferior graft maturity to the AMB until 24 months after surgery. For clinical relevance, the correct understanding of serial changes in graft maturation may potentially be used in decision-making regarding a return to sports.

LEVEL OF EVIDENCE

Prospective case series, Level IV.

Significant anterior enlargement of femoral tunnel aperture after hamstring ACL reconstruction, compared to bone-patellar tendon-bone graft

PURPOSE

This study aimed to retrospectively compare the enlargement and migration of the femoral tunnel aperture after anatomic rectangular tunnel anterior cruciate ligament (ACL) reconstruction with a bone-patella tendon-bone (BTB) or hamstring tendon (HT) graft using three-dimensional (3-D) computer models.

METHODS

Thirty-two patients who underwent ACL reconstruction and postoperative computed tomography (CT) at 3 weeks and 6 months were included in this study. Of these, 20 patients underwent ACL reconstruction with a BTB graft (BTBR group), and the remaining 12 with an HT graft (HTR group). The area of the femoral tunnel aperture was extracted and measured using a 3-D computer model generated from CT images. Changes in the area and migration direction of the femoral tunnel aperture during this period were compared between the two groups.

RESULTS

In the HTR group, the area of the femoral tunnel aperture was significantly increased at 6 months compared to 3 weeks postoperatively (P < 0.05). The average area of the femoral tunnel aperture at 6 months postoperatively was larger by 16.0 ± 12.4% in the BTBR group and 41.9 ± 22.2% in the HTR group, relative to that measured at 3 weeks postoperatively (P < 0.05). The femoral tunnel aperture migrated in the anteroinferior direction in the HTR group, and only in the inferior direction in the BTBR group.

CONCLUSIONS

The femoral tunnel aperture in the HTR group was significantly more enlarged and more anteriorly located at 6 months after ACL reconstruction, compared to the BTBR group.

LEVEL OF EVIDENCE

IV.

Double-Bundle Anterior Cruciate Ligament Reconstruction Using Hamstring Tendon Hybrid Grafts in Patients Over 40 Years of Age: Comparisons Between Different Age Groups

Background:

Several recent studies have reported that favorable clinical results and a high level of patient satisfaction can generally be obtained with no increased risk of complications after single-bundle anterior cruciate ligament (ACL) reconstruction performed in patients >40 years of age. However, no studies have yet clarified the age-based differences in clinical outcomes after double-bundle reconstruction.

Purpose:

To compare clinical outcomes after double-bundle ACL reconstruction using hamstring tendon hybrid grafts between patients in 2 different age groups: ≥40 years and <40 years.

Study Design:

Cohort study; Level of evidence, 3.

Methods:

A retrospective study was conducted using 96 patients (48 men, 48 women ; mean age, 37 years) who underwent unilateral ACL reconstruction between 2008 and 2011. These patients were divided into 2 groups: group M included patients ≥40 years of age (n = 40 patients), and group Y included patients <40 years of age (n = 56 patients). All patients underwent the same anatomic double-bundle ACL reconstruction procedure. Clinical outcomes were evaluated at 2 years after surgery. Tunnel enlargement was also evaluated by computed digital radiography at 1 week and 2 years after surgery.

Results:

Mean postoperative side-to-side differences in anterior laxity were 0.5 ± 1.9 mm and 1.2 ± 1.5 mm in groups M and Y, respectively; there was a significant difference between the 2 groups (P = .039). There were no significant differences between the groups in Lysholm knee scores, International Knee Documentation Committee (IKDC) scores, or peak muscle torque of the hamstring. On the other hand, peak muscle torque of the quadriceps was significantly lower in group M (81%) than in group Y (89%) (P = .025). With respect to femoral tunnel enlargement, the posterolateral tunnel in group M was significantly larger than that in group Y on anteroposterior and lateral radiographs (P = .015 and P = .002, respectively).

Conclusion:

Equivalent clinical outcomes were seen between the 2 age groups after double-bundle ACL reconstruction. Postoperative anterior laxity was significantly less in older patients than in younger patients, however, older patients had significantly less quadriceps muscle strength than younger patients. Surgeons should be aware of residual muscle weakness and tunnel enlargement when performing double-bundle ACL reconstruction in older patients.