Prospective randomized comparison of anatomic single- and double-bundle anterior cruciate ligament reconstruction

Purpose

To determine if anatomic double-bundle anterior cruciate ligament (ACL) reconstruction is superior to anatomic single-bundle reconstruction in restoring the stabilities and functions of the knee joint.

Methods

A prospective randomized clinical study was done to compare the results of 32 cases of anatomic single-bundle ACL reconstruction and 34 cases of anatomic double-bundle ACL reconstruction with average follow-up of 16.3 ± 3.1 months. Tunnel placements of all the cases were measured on 3D CT. Clinical results were collected after reconstruction; graft’s appearance, meniscus status and cartilage state under arthroscopy were compared and analysed too.

Results

Tunnel placements, confirmed with 3D CT, were in the anatomic positions as described in literature both in SB and DB group. No differences were found between SB and DB groups in clinical outcome scores, pivot shift test and KT 1000 measurements (average side-to-side difference for anterior tibial translation was 0.7 mm in SB group and 1.0 mm in DB group). More than 70 % of the single-bundle graft and AM bundle graft in DB group appeared excellent, but only 44.1 % of PL bundle grafts in DB group were excellent and 11.8 % were in poor state. No new menisci tear was found either in SB or DB group, however, in DB group cartilage damages in medial patella-femoral joint occurred in 38.2 % cases. This rate was significantly higher than in the SB group which is only 9.3 %.

Conclusion

Both single- and double-bundle anatomic ACL reconstruction can restore the knee’s stability and functions very well. However, more incidences of poor PL status and medial patellar-femoral cartilage damage may occur in double-bundle ACL reconstruction.

Level of evidence

Randomized controlled trial, Level I.     

Gender differences following computer-navigated single- and double-bundle anterior cruciate ligament reconstruction

Purpose

Female patients not only demonstrate an increased risk for injury, but also a poorer response following anterior cruciate ligament (ACL) rupture. However, no study has investigated gender-related differences between computer-navigated single-bundle (SB) and double-bundle (DB) ACL reconstruction. The aim of this study was to evaluate the effects of gender on the outcome of computer-navigated SB and DB ACL reconstruction and to present reference values.

Methods

A retrospective review of 55 consecutive patients who underwent SB (15 males, 12 females) and DB (18 males, 10 females) ACL reconstruction with autogenous hamstring tendon grafts and showed a minimum follow-up of 24 months was conducted. Intraoperatively, the anteroposterior and rotational laxity were measured and the follow-up examination included pivot-shift testing, KT-1000 arthrometer testing, International Knee Documentation Committee (IKDC) form, the Lysholm score and Tegner score.

Results

Pre-operatively, female patients showed a significant higher internal rotation in (p < 0.001) both the SB and DB group. Regarding the post-operative reduction in internal rotation, females in the SB group revealed a greater reduction compared to males (p < 0.001), whereas females in the DB group revealed a significantly greater post-operative reduction in anterior–posterior translation (p = 0.04). Female patients following DB ACL reconstruction presented a significant worse IKDC score, Lysholm score and Tegner score compared to male patients. All score values of the female DB group were worse than in the female SB group. In contrast, male patients showed better results of all examined clinical scores following DB procedure compared to SB technique.

Conclusion

Female patients who underwent computer-navigated DB ACL reconstruction exhibited significantly worse outcome scores than males who underwent DB ACL reconstruction. The gender-based relationship between joint function and outcome after ACL reconstruction remains unclear and requires further investigation.

Level of evidence

Retrospective case–control series, Level III.     

Anatomic ACL reconstruction produces greater graft length change during knee range-of-motion than transtibial technique

Purpose

Because distance between the knee ACL femoral and tibial footprint centrums changes during knee range-of-motion, surgeons must understand the effect of ACL socket position on graft length, in order to avoid graft rupture which may occur when tensioning and fixation is performed at the incorrect knee flexion angle. The purpose of this study is to evaluate change in intra-articular length of a reconstructed ACL during knee range-of-motion comparing anatomic versus transtibial techniques.

Methods

After power analysis, seven matched pair cadaveric knees were tested. The ACL was debrided, and femoral and tibial footprint centrums for anatomic versus transtibial techniques were identified and marked. A suture anchor was placed at the femoral centrum and a custom, cannulated suture-centring device at the tibial centrum, and excursion of the suture, representing length change of an ACL graft during knee range-of-motion, was measured in millimeters and recorded using a digital transducer.

Results

Mean increase in length as the knee was ranged 120°–0° (full extension) was 4.5 mm (±2.0 mm) for transtibial versus 6.7 mm (±0.9 mm) for anatomic ACL technique. A significant difference in length change occurs during knee range-of-motion both within groups and between the two groups.

Conclusions

Change in length of the ACL intra-articular distance during knee range-of-motion is greater for anatomic socket position compared to transtibial position. Surgeons performing anatomic single-bundle ACL reconstruction may tension and fix grafts with the knee in full extension to minimize risk of graft stretch or rupture or knee capture during full extension. This technique may also result in knee anterior–posterior laxity in knee flexion.     

A new technique in double-bundle anterior cruciate ligament reconstruction with implant-free tibial fixation

Purpose

This case-series outcome study presents a surgical technique for anatomic double-bundle anterior cruciate ligament (ACL) reconstruction with 4-tunnel using two interference screws. There was a 2-year minimum follow-up.

Methods

From January to December 2009, an ACL 4-tunnel, anatomic, double-bundle reconstruction was performed on 27 patients. Double-strand hamstring tendon grafts were used in each femoral tunnel as well as two interference screws. Tibial fixation was insured through manual tension, by tying non-absorbable sutures on the bone bridge between the two tunnels at 20° of knee flexion. Clinical assessments included the International Knee Documentation Committee (IKDC) and Lysholm knee scores, range of motion (ROM), pivot-shift test, single-leg hop, and quadriceps-hamstrings strength tests using a hand-held dynamometer. Anterior knee laxity was also assessed using a rolimeter. A single examiner performed all testing pre-operatively at 6 months and during the 2-year follow-up.

Results

All patients were assessed during the 2-year follow-up. At that time, 92 % of the patients presented normal anterior laxity (average, 1.3 ± 0.5 mm) and rotational knee stability. No statistical side-to-side difference was found for ROM, muscle strength, single-leg hop, and function (n.s.). All patients presented a normal knee function according to the IKDC and the Lysholm score. In addition, no infection, graft failure, or pain were observed at the harvesting site.

Conclusion

The study shows that satisfactory results in relation to knee laxity, function, and strength can be achieved with the implant-free tibial fixation in the ACL double-bundle reconstruction with two interference screws.

Level of evidence

Therapeutic case series, Level IV.

     

Comparison of double-bundle anterior cruciate ligament (ACL) reconstruction and single-bundle reconstruction with remnant pull-out suture

Purpose

The purpose of this study was to evaluate the stability and functional outcomes of anterior cruciate ligament (ACL) reconstruction by tensioning of the ACL remnant using pull-out sutures compared with ACL double-bundle reconstruction.

Methods

Forty-four patients were included in single-bundle reconstruction with remnant tensioning group (Group 1), and 56 patients were included in the double-bundle reconstruction group (Group 2). The remnant tissue was tensioned to the direction of posterolateral bundle, which unrelated to the type of remnant bundle. Objective knee stability was evaluated by anterior stress radiography, KT-1000 and lateral pivot shift tests. The Tegner activity scale, International Knee Documentation Committee and OrthopädischeArbeitsgruppeKnie scoring systems were used for clinical evaluation.

Results

No statistically significant intergroup differences were observed in mechanical stability and clinical results (n.s). However, surgical time of remnant tensioning group is shorter than double-bundle reconstruction group (P = 0.005).

Conclusion

Remnant tensioning suture with single-bundle reconstruction could be used with positive results as good as double-bundle technique if a good ACL remnant was found bridging the femur and tibia, rather than debride or damage to the remnant tissue during operation.

Level of evidence

Retrospective, comparative cohort study, Level IV.     

Anatomic double bundle ACL reconstruction outperforms any types of single bundle ACL reconstructions in controlling dynamic rotational laxity

Purpose

To compare the different types of ACL reconstructions in terms of knee dynamic laxity evaluated by acceleration.

Methods

Sixteen fresh frozen cadaveric knees were used. Pivot shift test was manually performed while monitoring the tibial acceleration by use of a triaxial accelerometer. The test was repeated before and after the ACL resection and reconstruction. Three types of ACL reconstruction were tested: (1) Anatomic Single-Bundle reconstruction (n = 8), the graft was placed at the center of the ACL footprint for the both femoral and tibial sides (tunnel diameter: 8mm); (2) Conventional Single-Bundle reconstruction (n = 8), the graft was placed from the tibial PL footprint to femoral high AM position (tunnel diameter: 8mm) and (3) Anatomic Double-Bundle reconstruction (n = 8). The acceleration in each of three x-y-z directions and the overall magnitude of acceleration was calculated to evaluate dynamic rotational laxity and compared between different ACL reconstructions.

Results

The overall magnitude of acceleration was significantly different between ACL intact and deficient knees (p < 0.0001). The acceleration was reduced by the DB ACL reconstruction to the intact level (n.s.), but the two SB ACL reconstruction failed to achieve the intact level of the acceleration (p = 0.0002non-anatomic SB, p < 0.0001 anatomic SB).

Conclusion

The anatomic DB reconstruction better restores dynamic rotational laxity when compared to the SB ACL reconstructions no matter if the tunnel placement was anatomic. The anatomic DB reconstruction better restores dynamic rotational laxity when compared to both anatomic and non-anatomic SB ACL reconstruction. For this reason anatomic DB ACL reconstruction is recommended for cases where rotational laxity is an issue.

     

Arthroscopic single-bundle ACL reconstruction with modified double-layer bone-patellar tendon-bone allograft

Purpose

The objective of present study was to introduce a modified double-layer bone-patellar tendon-bone (BPTB) allograft for arthroscopic single-bundle ACL reconstruction and investigate the clinical outcomes.

Methods

From 2007 to 2009, a total of 136 patients underwent arthroscopic single-bundle ACL reconstructions with BPTB allograft. Of which, 66 patients were with double-layer BPTB allograft (Group 1), and 70 patients were with conventional BPTB allograft (Group 2). Clinical outcomes including Lachman and pivot-shift tests, KT-1000 arthrometer measurements, and Lysholm and Tegner activity scores were compared between the two groups at a 2-year minimum follow-up.

Results

Forty-six patients in each group were at a two-year minimum follow-up. The mean side-to-side difference on the KT-1000 arthrometer was 1.2 ± 1.2 mm for group 1 and 2.1 ± 1.9 mm for group 2, with significant difference between the two groups (p = 0.017). The knee function was significantly better for group 1 than for group 2, because the mean Lysholm score was 94.2 ± 4.8 points versus 86.6 ± 7.1 points (p = 0.000), and the median Tegner score was 8 (range 5–10) points versus 6 (range 4–10) points (p = 0.001).

Conclusions

On the basis of the KT-1000 arthrometer evaluation and clinical measures, single-bundle ACL reconstruction with double-layer BPTB allograft achieves significantly lesser anterior laxity and better knee function than a single-layer allograft reconstruction.

Level of evidence

Therapeutic, retrospective comparative study, Level III.     

Rotational and translational laxity after computer-navigated single- and double-bundle anterior cruciate ligament reconstruction

Based on biomechanical cadaver studies, anatomic double-bundle reconstruction of the anterior cruciate ligament (ACL) was introduced to achieve better stability in the knee, particularly in respect of rotatory loads. Previously, the success of ACL reconstruction was believed to be mainly dependent on correct positioning of the graft, irrespective of the number of reconstructed bundles for which computer-assisted surgery was developed to avoid malpositioning of the tunnel. The aim of the present study is to compare rotational and translational stability after computer-navigated standard single-bundle, and anatomic double-bundle ACL reconstruction. The authors investigated 55 consecutive patients who had undergone the single-bundle or double-bundle ACL reconstruction procedure with the use of autogenous hamstring tendon grafts and EndoButton^® fixation, and the patients had been followed for a minimum period of 24 months. Intraoperative, anteroposterior and rotational laxity was measured with the computer navigation system, and compared between groups. Both surgical procedures significantly reduced anteroposterior displacement (AP) and internal rotation (IR) of the tibia compared to the pre-operative ACL-deficient knee (P < 0.05). No significant differences were registered between groups with regard to anteroposterior displacement of the tibia. A significantly greater reduction in internal rotation was noted in the double-bundle group (15.6°) compared to the single-bundle group (7.1°). The IKDC and Lysholm score were significantly higher in the double-bundle group. However, the results were excellent in both groups. The use of a computer-assisted ACL reconstruction, which is a highly accurate method of graft placement, could be useful for inexperienced surgeons to avoid malposition. Whether double-bundle ACL reconstruction, which was associated with improved rotational laxity and significantly better IKDC and Lysholm scores compared to the standard single-bundle ACL reconstruction procedure, provide an influence in terms of avoiding osteoarthritis or meniscus degeneration, long-term results of at least 5 years are needed.     

Double-bundle reconstruction results in superior clinical outcome than single-bundle reconstruction

Purpose

To compare the short- and long-term clinical outcomes of the double-bundle (DB) anterior cruciate ligament (ACL) reconstruction with those of single-bundle (SB) ACL reconstruction.

Methods

An electronic search of the database PubMed (1966–September 2011), EMBASE (1984–September 2011), and Cochrane Controlled Trials Register (CENTRAL; 3rd Quarter, 2011) was undertaken to identify relevant studies. Main clinical outcomes were knee stability measurements including KT-1000 arthrometer measurement, Pivot shift test, and Lachman test, and clinical outcome measurements including International Knee Documentation Committee (IKDC), Lysholm knee score, Tegner activity score, and complications.

Results

Eighteen studies were finally included in this meta-analysis, which were all classified as high risk of bias according to the Collaboration’s recommended tool. It is seen that compared to SB ACL reconstruction, DB ACL reconstruction results in a KT-1000 arthrometer outcome 0.63 and 1.00 mm closer to the normal knee in a short- and long-term follow-up, respectively. Our results also reveal that DB-treated patients have a significantly higher negative rate of the pivot shift test (p < 0.00001 and = 0.006 in a short- and long-term follow-up, respectively) and Lachman test (n.s. and p < 0.0001 in a short- and long-term follow-up, respectively) compared to SB-treated patients. As for the clinical outcome measurements, a significant difference is found between SB versus DB ACL reconstruction regarding the IKDC (p = 0.006 and < 0.0001 in a short- and long-term follow-up, respectively) and complications (p = 0.03), while there is no significant difference between the two groups regarding Lysholm knee score (n.s.) and Tegner activity score (n.s.).

Conclusion

Overall, double-bundle ACL reconstruction yields better clinical outcomes when compared to single-bundle ACL reconstruction.

Levels of evidence

II.     

Biomechanical comparison of different graft positions for single-bundle anterior cruciate ligament reconstruction

Purpose

Recent reports have highlighted the importance of an anatomic tunnel placement for anterior cruciate ligament (ACL) reconstruction. The purpose of this study was to compare the effect of different tunnel positions for single-bundle ACL reconstruction on knee biomechanics.

Methods

Sixteen fresh-frozen cadaver knees were used. In one group (n = 8), the following techniques were used for knee surgery: (1) anteromedial (AM) bundle reconstruction (AM–AM), (2) posterolateral (PL) bundle reconstruction (PL–PL) and (3) conventional vertical single-bundle reconstruction (PL-high AM). In the other group (n = 8), anatomic mid-position single-bundle reconstruction (MID–MID) was performed. A robotic/universal force-moment sensor system was used to test the knees. An anterior load of 89 N was applied for anterior tibial translation (ATT) at 0°, 15°, 30° and 60° of knee flexion. Subsequently, a combined rotatory load (5 Nm internal rotation and 7 Nm valgus moment) was applied at 0°, 15°, 30° and 45° of knee flexion. The ATT and in situ forces during the application of the external loads were measured.

Results

Compared with the intact ACL, all reconstructed knees had a higher ATT under anterior load at all flexion angles and a lower in situ force during the anterior load at 60° of knee flexion. In the case of combined rotatory loading, the highest ATT was achieved with PL-high AM; the in situ force was most closely restored with MIDMID, and the in situ force was the highest AM–AM at each knee flexion angle.

Conclusion

Among the techniques, AM–AM afforded the highest in situ force and the least ATT.     

Effect of femoral tunnel position on graft tension curves and knee stability in anatomic double-bundle anterior cruciate ligament reconstruction

Purpose

To evaluate the effect of the femoral tunnel position of the anteromedial bundle (AMB) and the posterolateral bundle (PLB) on the graft tension curves and knee stability in anatomic double-bundle anterior cruciate ligament (ACL) reconstruction.

Methods

Forty-five patients who underwent anatomic double-bundle ACL reconstruction were included. AMB and PLB were provisionally fixed to a graft tensioning system in the following settings during surgery: (1) AMB at 20° and PLB at 0° (A20P0), (2) AMB at 20° and PLB at 20° (A20P20), and (3) AMB at 20° and PLB at 45° (A20P45). Bundle tension was recorded during knee flexion–extension. A pivot shift test was also evaluated. Femoral tunnel positions of the AMB and PLB were then assessed by three-dimensional computed tomography, and the correlation between femoral tunnel position and tension change pattern or residual pivot shift was evaluated.

Results

The depth of the PLB tunnel position was correlated with the extent of tension reduction in the PLB between 0° and 30° irrespective of graft fixation settings, while neither the AMB tunnel position nor the height of the PLB tunnel position affected the tension change pattern. Ten cases showed grade 1 pivot shift only in the A20P0 setting. The PLB tunnel position in the pivot shift-positive cases was significantly deeper than that in the pivot shift-negative cases (27.5 ± 6.2 and 34.1 ± 5.5 %, respectively, P = 0.002).

Conclusions

In anatomic double-bundle reconstruction, deeper PLB tunnel position was correlated with the larger tension reduction in the PLB between 0° and 30°. Fixation of the AMB at 20° and the PLB at 0° resulted in residual pivot shift phenomenon in 10/45 cases, and the PLB tunnel position in the pivot shift-positive cases was significantly deeper than that in the pivot shift-negative cases. In anatomic double-bundle reconstruction, the placement of PLB femoral tunnel must not be too deep, as it might lead to significant tension reduction in the PLB near extension and thus insufficient tension in the PLB, resulting in residual pivot shift phenomenon.

Level of evidence

IV.     

Anatomic anterior cruciate ligament (ACL) reconstruction: a global perspective. Part 1

Purpose

In August 2011, orthopaedic surgeons from more than 20 countries attended a summit on anatomic anterior cruciate ligament (ACL) reconstruction. The summit offered a unique opportunity to discuss current concepts, approaches, and techniques in the field of ACL reconstruction among leading surgeons in the field.

Methods

Five panels (with 36 panellists) were conducted on key issues in ACL surgery: anatomic ACL reconstruction, rehabilitation and return to activity following anatomic ACL reconstruction, failure after ACL reconstruction, revision anatomic ACL reconstruction, and partial ACL injuries and ACL augmentation. Panellists’ responses were secondarily collected using an online survey.

Results

Thirty-six panellists (35 surgeons and 1 physical therapist) sat on at least one panel. Of the 35 surgeons surveyed, 22 reported performing “anatomic” ACL reconstructions. The preferred graft choice was hamstring tendon autograft (53.1 %) followed by bone-patellar tendon-bone autograft (22.8 %), allograft (13.5 %), and quadriceps tendon autograft (10.6 %). Patients generally returned to play after an average of 6 months, with return to full competition after an average of 8 months. ACL reconstruction “failure” was defined by 12 surgeons as instability and pathological laxity on examination, a need for revision, and/or evidence of tear on magnetic resonance imaging. The average percentage of patients meeting the criteria for “failure” was 8.2 %.

Conclusions

These data summarize the results of five panels on anatomic ACL reconstruction. The most popular graft choice among surgeons for primary ACL reconstructions is hamstring tendon autograft, with allograft being used most frequently employed in revision cases. Nearly half of the surgeons surveyed performed both single- and double-bundle ACL reconstructions depending on certain criteria. Regardless of the technique regularly employed, there was unanimous support among surgeons for the use of “anatomic” reconstructions using bony and soft tissue remnant landmarks.

Level of evidence

V.     

Anteromedial versus central single-bundle graft position: which anatomic graft position to choose?

Purpose

To compare the time-zero stability of an anatomic anteromedial (AM) single-bundle ACL reconstruction to an anatomic central (CTR) single-bundle ACL reconstruction.

Methods

Twelve (6 paired) hip to knee cadaveric specimens were studied. Using custom ACL computer navigation software, a Lachman test and a previously validated, navigated mechanized pivot shift test were performed on 4 separate experimental groups in each specimen: (1) intact ACL, (2) ACL deficient with total medial and lateral meniscectomy, (3) following anatomic AM single-bundle ACL reconstruction, and (4) after anatomic CTR single-bundle ACL reconstruction. Maximum anterior tibial translation in each group was measured.

Results

Lachman: No significant difference was observed between the AM and CTR reconstructions (n.s.) or between reconstruction and the intact ACL (3.4?±?1.7?mm) (n.s.). Pivot Shift: Both the AM and CTR ACL reconstructions significantly reduced anterior translation relative to the ACL/menisci-deficient condition (lateral compartment: 8.9?±?3.8 mm and 6.75?±?4.6 mm vs. 17.25?±?3.5?mm, respectively; P?P?P?P?Conclusions It has been shown that there was no difference in the time-zero biomechanical stability between an anatomic anteromedial and anatomic central single-bundle ACL reconstruction. Given the current debate on the best anatomic ACL reconstruction technique, anatomic socket position in either the anteromedial or central locations provides similar time-zero biomechanics.     

The accuracy of bone tunnel position using fluoroscopic-based navigation system in anterior cruciate ligament reconstruction

Purpose

The first purpose of this study was to examine whether fluoroscopic-based navigation system contributes to the accuracy and reproducibility of the bone tunnel placements in single-bundle anterior cruciate ligament (ACL) reconstruction. The second purpose was to investigate the application of the navigation system for double-bundle ACL reconstruction.

Methods

A hospital-based case–control study was conducted, including a consecutive series of 55 patients. In 37 patients who received single-bundle ACL reconstruction, surgeries were performed with this system for 19 knees (group 1) and without this system for 18 knees (group 2). The positioning of the femoral and tibial tunnels was evaluated by plain sagittal radiographs. In 18 patients who received double-bundle ACL reconstruction using the navigation system (group 3), the bone tunnel positions were assessed by three-dimensional computed tomography (3D-CT). Clinical assessment of all patients was followed with the use of Lysholm Knees Score and IKDC.

Results

Taking 0% as the anterior and 100% as the posterior extent, the femoral tunnels were 74.9?±?3.0% in group 1 and 71.5?±?5.8% in group 2 along Blumensaat’s line, and the tibial tunnels were 42.3?±?1.4% in group 1 and 42.5?±?4.6% in group 2 along the tibia plateau. The bone tunnel positions in group 1 were located significantly closer to the position planned preoperatively and varied less in both femur and tibial side, compared with those without navigation (group 2). (Femur: P?P?Conclusion The fluoroscopic-based navigation system contributed to the more reproducible placement of the bone tunnel during single-bundle ACL reconstruction compared with conventional technique. Additionally, this device was also useful for double-bundle ACL reconstruction.

Level of evidence

Case–control study, Therapeutic study, Level III.     

Graft size after anterior cruciate ligament reconstruction

Purpose

The native anterior cruciate ligament (ACL) is composed of two distinct bundles, the anteromedial (AM) and posterolateral (PL), and both have been shown to be reliably measured on magnetic resonance imaging (MRI). The purpose of this study was to measure the size of the AM and PL bundles after ACL double-bundle reconstructions on MRI and compare this to the relative graft size at the time of surgery.

Methods

Between January 2007 and April 2010, 85 knees were identified after allograft double-bundle ACL reconstruction with post-operative MRI (1.5 T) and met inclusion criteria. On standard sagittal, coronal and oblique coronal MRIs, the AM and PL bundles were delineated and the midsubstance width of the ACL graft was measured. The images were independently measured in a blinded fashion by two observers. Linear and curvilinear regression analysis was used to analyse the relationship between graft size and time after reconstruction.

Results

The mean age of the patients was 24.6 years (SD 10.4). Mean time from surgery to post-operative MRI was 271.5 days (SD 183.4). The mean percentage of the original size of the AM bundle was 86.9 % (SD 9.9) and of the PL bundle was 88.6 % (SD 9.9). There was no correlation between the relative size of the AM graft and the time from surgery (r = 0.3, n.s.) and no significant relationship for the PL graft (r = 0.1, n.s).

Conclusion

On average, there was no graft enlargement of the AM and PL grafts 275.1 days after allograft ACL double-bundle reconstruction, as the mean relative graft size was less than 100 % on MRI. This study suggests that surgeons, who use allografts, should measure the ACL and replace it with a similar size, as there is a low risk of hypertrophy of the graft within one year post-operative.

Level of evidence

IV.     

Restoration of sagittal and transverse plane proprioception following anatomic double-bundle ACL reconstruction

Purpose

To investigate the restoration of knee proprioception after anatomic double-bundle ACL reconstruction.

Methods

Eleven subjects who underwent anatomic double-bundle ACL reconstruction (12.5–15 months following surgery) and eleven healthy control subjects participated in the study. Sagittal and transverse plane threshold to detect passive motion (TTDPM) were assessed utilizing a customized isokinetic dynamometer by passively rotating the tibia about a fixed femur in both the sagittal plane and transverse plane at 0.25°/s until the subject signalled recognition of movement and movement direction. Based on the normality assumption, either dependent t test or Wilcoxon test was utilized to determine whether significant differences were present between the ACL-reconstructed and the uninjured contralateral limbs. Independent t test or Mann–Whitney test was utilized to compare between the ACL-reconstructed/uninjured contralateral and the external control limbs.

Results

There were no significant differences in TTDPM measurement in eleven out of twelve comparisons between the ACL-reconstructed and the uninjured contralateral/external control limbs. The only statistical significant difference was found on TTDPM towards internal rotation direction from the externally rotated-test position between the ACL-reconstructed and the uninjured contralateral limbs (p = 0.01).

Conclusions

Based on a small sample of eleven subjects, the current results indicate a restoration of both sagittal and transverse plane TTDPM following the anatomic double-bundle ACL reconstruction.

Level of evidence

III.     

The effect of anterior cruciate ligament graft rotation on knee biomechanics

Purpose

The purpose of this study was to evaluate the effects on knee biomechanics of rotating the distal end of the bone-patellar tendon graft 90° in anatomic single-bundle (SB) anterior cruciate ligament (ACL) reconstruction with a porcine model.

Methods

Twenty (n = 20) porcine knees were evaluated using a robotic testing system. Two groups and three knee states were compared: (1) intact ACL, (2) deficient ACL and (3) anatomic SB ACL reconstruction with (a) non-rotated graft or (b) rotated graft (anatomic external fibre rotation). Anterior tibial translation (ATT), internal (IR) and external rotation (ER) and the in situ tissue force were measured under an 89-N anterior tibial (AT) load and 4-N m internal and external tibial torques.

Results

A significant difference from the intact ACL was found in ATT at 60° and 90° of knee flexion for rotated and non-rotated graft reconstructions (p < 0.05). There was a significant difference in the in situ force from the intact ACL with AT loading for rotated and non-rotated graft reconstructions at 60° and 90° of knee flexion (p < 0.05). Under IR loading, the in situ force was significantly different from the intact ACL at 30° and 60° of knee flexion for rotated and non-rotated graft reconstructions (p < 0.05). There were no significant differences in ATT, IR, ER and the in situ force between rotated and non-rotated reconstructions.

Conclusion

Graft rotation can be used with anatomic SB ACL reconstruction and not have a deleterious effect on knee anterior and rotational biomechanics. This study has clinical relevance in regard to the use of graft rotation to better reproduce the native ACL fibre orientation in ACL reconstruction.

     

Calcium phosphate-hybridized tendon grafts reduce femoral bone tunnel enlargement in anatomic single-bundle ACL reconstruction

Purpose

This study aimed to clarify the effect of calcium phosphate (CaP)-hybridized tendon grafting versus unhybridized tendon grafting on the morphological changes to the bone tunnels at the aperture 1 year after anatomic single-bundle anterior cruciate ligament (ACL) reconstruction.

Methods

Seventy-three patients were randomized to undergo the CaP (n = 37) or the conventional method (n = 36). All patients underwent computed tomography (CT) evaluation 1 week and 1 year post-operatively. The femoral and tibial tunnels at the aperture were evaluated on reconstructed 3D CT images. Changes in the cross-sectional area (CSA) and diameters of the femur and the tibia, and the translation rate of the tunnel walls and the morphological changes of both tunnels were assessed.

Results

There was a significant reduction in the increase in the CSA and the anterior–posterior and proximal–distal tunnel diameters on the femoral side in the CaP group as compared with the conventional group. On the femoral side, the translation rate of the posterior wall was significantly larger in the CaP group than in the conventional group, whereas the translation rate of the distal wall was significantly smaller in the CaP group than in the conventional group.

Conclusions

As compared with the conventional method, the CaP-hybridized tendon graft reduced bone tunnel enlargement on the femoral side 1 year after anatomic single-bundle ACL reconstruction due to an anterior shift of the posterior wall and reduced distal shift in the femoral bone tunnel. Clinically, the CaP-hybridized tendon grafts can prevent femoral bone tunnel enlargement in anatomic single-bundle ACL reconstruction.

Level of evidence

I.

     

Clinical comparison of two suspensory fixation devices for anatomic double-bundle anterior cruciate ligament reconstruction

Purpose

The aim of this study was to compare the operation time required and the clinical outcome 2?years postoperatively, after anatomic double-bundle ACL reconstructions using hamstring tendon grafts fixed with either the EndoButton-CL-BTB^? (ECL-BTB) or the EndoButton-CL^? (ECL).

Methods

Forty-six patients, who underwent anatomic double-bundle ACL reconstruction, were non-randomly divided into 2 groups. Patients with a combined ligament injury or complete meniscal tear were excluded from this study. In group I, an ECL was used with 23 patients. In group II, an ECL-BTB was used with the remaining 23 patients. In groups I and II, the ECL or ECL-BTB was attached to the femoral ends of the hamstring tendon autografts. In both groups, a polyester tape was connected in series with the tibial ends of the grafts. The patients were examined with standard clinical evaluations at 2?years after surgery.

Results

The operation time in group II was significantly shorter than that in group I (P?=?0.0459). Concerning the intra- and postoperative complications, there were no serious complications in either group. No significant differences were found between the 2 groups in terms of knee laxity measurements, the peak muscle torque of quadriceps and hamstrings, the Lysholm score and the IKDC evaluation.

Conclusions

This study demonstrated that the usage of the ECL-BTB for graft preparation significantly shortens the total operation time in comparison with the ECL and that there were no significant differences in the 2-year clinical outcome and the intra- and postoperative complications between the 2 graft preparation procedures of the anatomic double-bundle ACL reconstruction. The ECL-BTB can be an alternative device for the hamstring tendon graft in double-bundle ACL reconstruction.

Level of evidence

Prospective comparative cohort study, Level II.     

The effect of anterior cruciate ligament graft orientation on rotational knee kinematics

Purpose

To determine whether coronal graft orientation and tunnel placement for single-bundle anterior cruciate ligament (ACL) reconstruction is associated with tibial rotation excursion during functional activities.

Methods

Eighty-four patients who had undergone ACL reconstruction over a ten-year time span had tibial rotation measured during level walking, using a three-dimensional motion analysis system. Fifty-two patients also had measures taken during the more dynamic task of single-limb landing. During the 10-year period, the position of the graft was deliberately changed from a vertical to more horizontal orientation in the coronal plane. Post-operative radiographs were analysed for the coronal graft orientation and femoral and tibial tunnel positions. Radiographic measurements of graft orientation and tunnel position were then correlated with the amount of tibial rotational excursion recorded during the walking and landing tasks.

Results

For the single-limb landing task, a significant positive correlation was observed between the coronal graft angle and rotational excursion (R = 0.35, R ²  = 0.12, p = 0.01). This indicated greater rotational excursion was associated with vertical graft orientation, but only explained 12 % of the variance. No correlations were found between coronal graft angle and tibial rotation during level walking.

Conclusions

These findings support the notion that ACL graft orientation may play a role in rotational kinematics of the ACL-reconstructed knee, particularly during higher impact activities.

Level of evidence

IV.