The effect of notchplasty in anterior cruciate ligament reconstruction: a biomechanical study in the porcine knee

Does Bone Regrow After Notchplasty in ACL Reconstruction? A Prospective Computed Tomography Study With 2-Year Follow-up

Background:

During notchplasty in anterior cruciate ligament (ACL) reconstruction, bone is excised from the lateral and roof area of the notch to widen the intercondylar space and avoid notch-graft impingement in extension. There are concerns that bone regrowth of the area will cause narrowing and increase the risk of complications.

Purpose:

To determine the possibility of late narrowing of the notch after notchplasty using computed tomography (CT) analysis.

Study Design:

Case series; Level of evidence, 4.

Methods:

Measurements were performed on CT scans (axial and sagittal planes with knee in extension) in patients who had undergone single-bundle anatomic ACL reconstruction using hamstring graft. Two axial image levels were used: at the anterior outlet and the anterior one-eighth level of the notch. The maximum notch height and width, the notch width at one-third and two-thirds of the preoperative notch midwidth height, the maximum condylar width, and the surface area of the lateral half of the notch were measured preoperatively and at 1 week and 2 years postoperatively.

Results:

Included were 20 consecutive patients (mean ± standard deviation age, 28 ± 7.3 years; follow-up, 24.2 ± 3.3 months). At the anterior notch outlet, the maximum notch width increased by 1.9 ± 1.7 mm at 1 week postoperatively and narrowed by 0.3 ± 1.1 mm at the final follow-up, while the maximum notch height increased by 1.7 ± 1.9 mm and narrowed by 0.8 ± 1.8 mm, respectively. At one-eighth of the roof length, the maximum notch width increased by 1.1 ± 1.7 mm at 1 week postoperatively and narrowed by 0.1 ± 1.1 mm at the final follow-up, and the maximum notch height increased by 1.2 ± 1.5 mm and narrowed by 0.5 ± 1.5 mm, respectively. All differences were statistically significant when comparing the pre- to the immediate postoperative measurements, and they were nonsignificant when comparing the immediate postoperative to the final follow-up measurements. The same applied for the ratio of maximum notch width to maximum condylar width, indicating no postoperative narrowing of the notch.

Conclusion:

Notch size-shape after a 2-mm notchplasty did not change significantly in stable knees during the first 2 years after anatomic ACL reconstruction. Surgeons should consider performing this adjuvant technique when there is notch-graft impingement during surgery.

The intercondylar fossa-A narrative review

The intercondylar fossa (“intercondylar notch,” IN) is a groove at the distal end of the femur, housing important stabilizing structures: cruciate ligaments and meniscofemoral ligaments. As the risk for injury to these structures correlates with changes to the IN, exact knowledge of its morphology, possible physiological and pathological changes and different approaches for evaluating it are important. The divergent ways of assessing the IN and the corresponding measurement methods have led to various descriptions of its possible shapes. Ridges at the medial and lateral wall are considered clinically important because they can help with orientation during arthroscopy, whereas ridges at the osteochondral border could affect the risk of ligament injury. Changes related to aging and sex differences have been documented, further emphasizing the importance of individual assessment of the knee joint. Overall, it is of the utmost importance to remember the interactions between the osseous housing and the structures within.

Anterior cruciate ligament femoral-tunnel drilling through an anteromedial portal: 3-dimensional plane drilling angle affects tunnel length relative to notchplasty

Background

Notchplasty is a surgical technique often performed during anterior cruciate ligament reconstruction (ACLR) with widening of the intercondylar notch of the lateral distal femur to avoid graft impingement. The purpose of this study was to correlate femoral-tunnel length with 3-dimensional (3D) drilling angle through the anteromedial (AM) portal with and without notchplasty.

Materials and methods

Computer data were collected from an anatomical study using 16 cadaveric knees. The anterior cruciate ligament (ACL) femoral insertion was dissected and outlined for gross anatomical observation. The dissected cadaveric knees were scanned by computed tomography (CT). Three-dimensional measurements were calculated using software (Geomagic, Inc., Research Triangle Park, NC, USA) and included the center of the ACL footprint and the size of the ACL femoral footprint. The femoral-tunnel aperture centers were measured in the anatomical posterior-to-anterior and proximal-to-distal directions using Bernard’s quadrant method. The ACL tunnel was created 3-demensionally in the anatomical center of femoral foot print of ACL using software (SolidWorks®, Corp., Waltham, MA, USA). The 8-mm cylinder shaped ACL tunnel was rested upon the anatomical center of the ACL footprint and placed in three different positions: the coronal plane, the sagittal plane, and the axial plane. Finally, the effect of notchplasty on the femoral-tunnel length and center of the ACL footprint were measured. All the above-mentioned studies performed ACLR using the AM portal.

Results

The length of the femoral tunnels produced using the low coronal and high axial angles with 5-mm notchplasty became significantly shorter as the femoral starting position became more horizontal. The result was 30.38 ± 2.11 mm on average at 20° in the coronal plane/70° in the axial plane/45° in the sagittal plane and 31.26 ± 2.08 mm at 30° in the coronal plane/60° in the axial plane/45° in the sagittal plane, respectively, comparing the standard technique of 45° in the coronal/45° in the axial/45° in the sagittal plane of 32.98 ± 3.04 mm (P < 0.001). The tunnels made using the high coronal and low axial angles with notchplasty became longer than those made using the standard technique: 40.31 ± 3.36 mm at 60° in the coronal plane/30° in the axial plane/45° in the sagittal plane and 50.46 ± 3.13 mm at 75° in the coronal plane/15° in the axial plane/45° in the sagittal plane (P < 0.001).

Conclusions

Our results show that excessive notchplasty causes the femoral tunnel to be located in the non-anatomical center of the ACL footprint and reduces the femoral-tunnel length. Therefore, care should be taken to avoid excessive notchplasty when performing this operation.

A study of knee anterior cruciate ligament biomechanics with respect to energy and relaxation

BACKGROUND

This research aimed to study the biomechanical properties of sheep tendon under torsion and the tendon energy absorption performance with an externally imposed initial force.

METHODS

Tendons of nine healthy knees of sheep were investigated. In both tests, we investigated energy and relaxation at rotations of 0°, 90°, 180°, and 360°. For both tensile force and tensile displacement at a sampling period of 100 milliseconds, the maximum value of 89 N was selected as the maximum tension state for 600 s of relaxation duration for testing relaxation, and analysed of the average force of the last 30 s.

FINDINGS

The difference of energy levels of the tendons are significant between twisted groups (180° and 360°) and untwisted group (0°) (P < 0.05); The relaxation force decreases significantly with twisted groups (90°,180°, and 360°) and untwists group (0°) (P < 0.05). The nine-group tendons show no significant difference at torsion 90° and 180° (P = 0.466). Peak force test shows significant differences between the twisted groups (90°,180°, and 360°) and untwisted group (0°) (P < 0.05).

INTERPRETATION

The torsion tendon has lower energy absorption and relaxation than the untwisted counterparts; thus, it may be more prone to damage. These results are useful for providing guidance on anterior cruciate ligament reconstruction.

Notchplasty alters knee biomechanics after anatomic ACL reconstruction

PURPOSE

The aims of this study were (1) to study the biomechanics of single-bundle anatomic ACL reconstructed knees with and without notchplasty using a robotic testing system and (2) to determine if there would be a difference between performing a small or large notchplasty.

METHODS

Fifteen fresh-frozen specimens were used in this study. The ACL reconstruction (ACL-R) was performed using an anatomic single-bundle technique with the 8 mm soft tissue graft fixed at 30° with suspensory fixation on the femoral side and a screw and washer on the tibial side. The notchplasty was then created with a burr. The following knee states were compared: (1) ACL-R, (2) ACL-R with a small (3 mm) notchplasty, and (3) ACL-R with a large (6 mm) notchplasty. Four loading conditions were applied: (1) an anterior drawer with an 89 N anterior tibial load, (2) simulated pivot-shift loading, (3) a 5 Nm internal rotational moment, and (4) a 5 Nm external rotational moment.

RESULTS

Under anterior tibial loading, anterior tibial translation increased, and graft force decreased significantly after ACL-R + 3 mm notchplasty and ACLR + 6 mm notchplasty compared to ACL-R alone at FE, 15° and 30° of knee flexion. There were no changes in either anterior tibial translation or graft force under simulated pivot-shift loading, internal rotational moment, or external rotational moment.

CONCLUSION

When added to anatomic ACL reconstruction, notchplasty increased anterior tibial translation and decreased graft forces during low knee flexion angles. There was no difference between a small and large notchplasty. The findings of this study are clinically relevant as the purpose of anatomic ACL reconstruction is to restore normal knee laxity, and while notchplasty may be helpful in avoiding graft impingement and improving visualization, removing even 3 mm of bone leads to biomechanical changes.

Arthroscopic centralization restores residual knee laxity in ACL-reconstructed knee with a lateral meniscus defect

PURPOSE

The aim of this study was to evaluate the effects of knee biomechanics with an irreparable lateral meniscus defect using the centralization capsular meniscus support procedure in the setting of the ACL-reconstructed knee in a porcine model. The hypothesis is the arthroscopic centralization will decrease the laxity and rotation of the ACL-reconstructed knee.

METHODS

Twelve fresh-frozen porcine knees were tested using a robotic testing system under the following loading conditions: (a) an 89.0 N anterior tibial load; (b) 4.0 N m internal and external rotational torques. Anatomic single-bundle ACL reconstruction with a 7 mm-diameter bovine extensor tendon graft was performed. A massive, middle segment, lateral meniscus defect was created via arthroscopy, and arthroscopic centralization was performed with a 1.4 mm anchor with a #2 suture. The LM states with ACL reconstruction evaluated were: intact, massive middle segment defect and with the lateral meniscus centralization procedure.

RESULTS

The rotation of the ACL reconstructed knee with the lateral meniscus defect was significantly higher than with the centralized lateral meniscus under an external rotational torque at 30° of knee flexion, and under an internal rotational torque at 30° and 45° of knee flexion. There were no systematic and consistent effects of LM centralization under anterior tibial translation.

CONCLUSIONS

In this porcine model, the capsular support of middle segment of the lateral meniscus using arthroscopic centralization improved the residual rotational laxity of the ACL-reconstructed knee accompanied with lateral meniscus dysfunction due to massive meniscus defect. This study quantifies the benefit to knee kinematics of arthroscopic centralization by restoring the lateral meniscal function.

Validation of Noncontact Anterior Cruciate Ligament Tears Produced by a Mechanical Impact Simulator Against the Clinical Presentation of Injury

BACKGROUND

Anterior cruciate ligament (ACL) injuries are catastrophic events that affect athletic careers and lead to long-term degenerative knee changes. As injuries are believed to occur within the first 50 milliseconds after initial contact during a rapid deceleration task, impact simulators that rapidly deliver impulse loads to cadaveric specimens have been developed. However, no impactor has reproducibly and reliably created ACL injures in a distribution that mimics clinical observation.

PURPOSE

To better understand ACL injury patterns through a cadaveric investigation that applied in vivo-measured external loads to the knee during simulated landings.

STUDY DESIGN

Controlled laboratory study.

METHODS

A novel mechanical impact simulator reproduced kinetics from in vivo-recorded drop landing tasks on 45 cadaveric knees. Specimens were exposed to a randomized order of variable knee abduction moment, anterior tibial shear, and internal tibial rotation loads before the introduction of an impulse load at the foot. This process was repeated until a hard or soft tissue injury was induced on the joint. Injuries were assessed by an orthopaedic surgeon, and ligament strain was recorded by implanted strain gauges.

RESULTS

The mechanical impact simulator induced ACL injuries in 87% of specimens, with medial collateral ligament (MCL) injuries in 31%. ACL tear locations were 71% femoral side, 21% midsubstance, and 9% tibial side. Peak strain before failure for ACL-injured specimens was 15.3% ± 8.7% for the ACL and 5.1% ± 5.6% for the MCL ( P < .001).

CONCLUSION

The ACL injuries induced by the mechanical impact simulator in the present study have provided clinically relevant in vitro representations of in vivo ACL injury patterns as cited in the literature. Additionally, current ligament strains corroborate the literature to support disproportionate loading of the ACL relative to the MCL during athletic tasks.

CLINICAL RELEVANCE

These findings indicate that the mechanical impact simulator is an appropriate model for examining independent mechanical variables, treatment techniques, and preventive interventions during athletic tasks leading up to and including an ACL injury. Accordingly, this system can be utilized to further parse out contributing factors to an ACL injury as well as assess the shortcomings of ACL reconstruction techniques in a dynamic, simulated environment that is better representative of in vivo injury scenarios.

Anterior cruciate ligament graft fixation first in anterior and posterior cruciate ligament reconstruction best restores knee kinematics

PURPOSE

To evaluate the effect of different graft fixation sequences in one-stage anterior cruciate ligament (ACL) and posterior cruciate ligament (PCL) reconstruction on (1) knee biomechanics and (2) tibiofemoral alignment.

METHODS

Twelve porcine knees were used in this study. Five fixation sequences were performed (angle indicating knee flexion): (a) PCL at 30° and ACL at 30°, (b) PCL at 90° and ACL at 30°, (c) ACL at 30° and PCL at 30°, (d) ACL at 30° and PCL at 90°, and (e) ACL and PCL simultaneous fixation at 30°. Anterior and posterior tibial translation was measured under an 89 N load. A 3-D digitizer was used to measure the change in anteroposterior (AP) tibiofemoral position.

RESULTS

None of the graft fixation sequences restored the AP laxity of the intact knee, and there are minimal differences in the in situ tissue forces in the ACL and PCL grafts. The reconstructions with fixation of the PCL graft first resulted in a significantly larger change in AP tibiofemoral position from the intact knee at 60° and 90° of knee flexion than the reconstructions with fixation of the ACL graft first (p < 0.05).

CONCLUSION

Fixation of the ACL graft at 30° of knee flexion followed by fixation of the PCL graft can best restore the tibiofemoral position of the intact knee. This study has clinical relevance in regard to the effect of graft fixation sequence on the position of the tibia relative to the femur in one-stage ACL and PCL reconstruction.

Evaluation of Posterior Cruciate Ligament and Intercondylar Notch in Subjects With Anterior Cruciate Ligament Tear: A Comparative Flexed-Knee 3D Magnetic Resonance Imaging Study

PURPOSE

To determine if posterior cruciate ligament (PCL) and intercondylar notch (IN) morphometries and volumetrics act as risk factors for anterior cruciate ligament (ACL) tears.

METHODS

A prospective case-controlled magnetic resonance imaging (MRI) study was conducted with subjects presenting noncontact knee injuries. Exclusion criteria were previous surgery, PCL tear, osteoarthritis, tumors, or infectious and inflammatory conditions. All participants underwent a flexed-knee 3-dimensional (3D) magnetic resonance imaging (MRI) to uniformly straighten PCL. MR images were independently reviewed by 2 radiologists and assessed for 2D and 3D measurements (bicondylar width; IN angle, depth, width, and cross-sectional area; PCL width, thickness, and cross-sectional area; and IN and PCL volumes). Clinical profiles were tabulated and subjects were divided into cases (ACL tear) and controls (without ACL tear).

RESULTS

The study was composed of 50 cases versus 52 controls (N = 102), with a mean age of 36.8 years. There was no difference between groups (P > .05) regarding age, gender, body mass index, time from injury, Tegner score, flexion angle, limb side, intensity of injury, or familial or opposite limb history of tear. Agreement between readers ranged from substantial to almost perfect. Subjects with ACL tear presented with lower IN width, lower IN minus PCL widths, lower Notch Width Index, higher PCL/IN width proportion, higher PCL thickness, lower IN depth minus PCL thickness, and higher PCL thickness/IN depth proportion (P < .05). Moreover, higher PCL/IN cross-sectional area proportion, higher PCL volumes (OR = 9.01), and higher PCL/IN volume proportion were also found in cases.

CONCLUSIONS

Our study shows that subjects with ACL tears present not only reduced IN but also larger PCL dimensions. These findings, isolated and combined, and especially PCL volume, might be suggestive as risk factors for ACL tears owing to the reduction of its space inside the IN.

LEVEL OF EVIDENCE

Level III, comparative group.

Medial collateral ligament reconstruction is necessary to restore anterior stability with anterior cruciate and medial collateral ligament injury

PURPOSE

The purpose of this study was to compare knee kinematics and graft forces in anterior cruciate ligament (ACL) reconstruction combined with one of two superficial medial collateral ligament (sMCL) reconstruction techniques (parallel or triangular vector sMCL reconstruction).

METHODS

Twenty porcine knees were divided into two groups (n = 20), parallel or triangular vector sMCL reconstruction, with both groups having anatomic single-bundle ACL reconstruction. The knees were tested under (1) an 89-N anterior tibial load, (2) 4 Nm internal and external rotational tibial torques, and (3) a 7 Nm valgus torque.

RESULTS

With ACL/sMCL co-injuries, single-bundle ACL reconstruction alone does not restore anterior, valgus, and internal stability. Triangular vector sMCL reconstruction better restored anterior stability, and parallel sMCL reconstruction better restored valgus stability.

CONCLUSION

This study showed that single-bundle ACL reconstruction alone was not able to restore anterior tibial translation, valgus rotation, and external rotation of the intact knee with combined ACL and sMCL injuries and sMCL reconstruction was also required. The combined ACL and parallel sMCL reconstruction better restored valgus and external rotation stability, while the combined ACL and triangular vector method better restored anterior tibial translation. With combined ACL and severe sMCL injury, both ligaments should be reconstructed. The two sMCL reconstruction techniques exhibited slightly different kinematics and graft force; however, there was not enough difference to recommend one over the other.

The influence of internal and external tibial rotation offsets on knee joint and ligament biomechanics during simulated athletic tasks

BACKGROUND

Following anterior cruciate ligament injury and subsequent reconstruction transverse plane tibiofemoral rotation becomes underconstrained and overconstrained, respectively. Conflicting reports exist on how rotations influence loading at the knee. This investigation aimed to determine the mechanical effects of internal and external tibial rotation offsets on knee kinematics and ligament strains during in vitro simulations of in vivo recorded kinematics.

METHOD

A 6-degree-of-freedom robotic manipulator arm was used to articulate 11 cadaveric tibiofemoral joint specimens through simulations of four athletic tasks produced from in vivo recorded kinematics. These simulations were then repeated with 4° tibial rotation offsets applied to the baseline joint orientation.

FINDINGS

Rotational offsets had a significant effect on peak posterior force for female motion simulations (P < 0.01), peak lateral force for most simulated tasks (P < 0.01), and peak anterior force, internal torque, and flexion torque for sidestep cutting tasks (P ≤ 0.01). Rotational offsets did not exhibit statistically significant effects on peak anterior cruciate ligament strain (P > 0.05) or medial collateral ligament strain (P > 0.05) for any task.

INTERPRETATION

Transverse plane rotational offsets comparable to those observed in anterior cruciate ligament deficient and reconstructed patients alter knee kinetics without significantly altering anterior cruciate ligament strain. As knee degeneration is attributed to abnormal knee loading profiles, altered transverse plane kinematics may contribute to this. However, altered transverse plane rotations likely play a limited role in anterior cruciate ligament injury risk as physiologic offsets failed to significantly influence anterior cruciate ligament strain during athletic tasks.

Effects of Notchplasty on Anterior Cruciate Ligament Reconstruction: A Systematic Review

Purpose  Notchplasty is a complementary surgical procedure often performed during anterior cruciate ligament reconstruction (ACLR) with the aim to widen the intercondylar notch and to avoid graft impingement. The aim of this review was to analyze the current literature evidence concerning the effects of notchplasty on clinical outcome after primary ACLR.

Methods  Cochrane Database of Systematic Reviews, the Cochrane Central Register of Controlled Trials, PubMed, and MEDLINE were used to search English language studies, from January 1990 to July 2015, concerning the effects of the notchplasty on ACLR, using the following keywords: “ACL” OR “anterior cruciate ligament” OR “ACL reconstruction” OR “anterior cruciate ligament reconstruction” AND “notch” OR “notchplasty” OR “intercondylar notch”. Randomized and nonrandomized trials, case series, technical notes, biomechanical studies and radiological study were included.

Results  At the final screening 16 studies were included. Despite widely used, the usefulness of notchplasty during ACLR remains unclear. Some concerns emerged regarding potential harmful effects of notchplasty, mostly related to the knee biomechanics and postoperative blood loss. Notchplasty can be useful in the treatment of arthrofibrosis and in presence of bony spurs of the notch both in primary and revision surgery. However, the level of evidence of available literature is poor and there is a strong need for randomized controlled trials investigating the role of notchplasty on ACLR.

Conclusion  We suggest being aware of potential complications following notchplasty during ACLR before deciding to perform notchplasty in primary ACLR, reserving it for the surgical management of arthrofibrosis, treatment of notch osteophytosis and revision ACLR.

Level of Evidence  Level IV, systematic review of level II-IV studies.

Biomechanical evaluation of knee endpoint during anterior tibial loading: Implication for physical exams

BACKGROUND

Physical exams that apply anterior tibial loads are typically used to evaluate knees with anterior cruciate ligament (ACL) injuries. The amount of anterior tibial translation that occurs during these exams can be difficult to assess due to a "soft" endpoint. Therefore, the objective of this study is to determine the biomechanical characteristics of the endpoint for the intact and ACL deficient knee using quantitative criteria.

METHODS

Eight porcine knees were tested using a robotic testing system. An 89N anterior tibial load was applied to the intact and ACL deficient knee at 30°, 45°, 60° and 75° of flexion. The stiffness of the toe and linear regions was determined from the load-translation curve. The width of the transition region was defined by the distance between the points where the best-fit lines used to define the stiffness of the toe and linear regions diverged from the load-translation curve.

RESULTS

Stiffness of the toe and linear regions significantly decreased after transecting the ACL at all flexion angles (71-85% and 38-62%, respectively). Width of the transition region was significantly increased in the ACL deficient knee at all flexion angles (approximately four to five times and four to nine times, respectively).

CONCLUSIONS

The novel quantitative criteria developed in this study have the potential to be deployed in clinical practice by coupling them with data from knee arthrometers that are commonly used in clinical practice. Thus, additional information from the load-translation curve can be provided to improve the diagnosis of ACL injury.

ACL Surgical Technique — Staying Out of Trouble

The incidence of ACL tear and reconstruction has increased over time, and failure of ACL reconstruction is not perfectly defined among surgeons. Atraumatic failure of ACL surgery represents approximately 70% of causes, and occurs in diagnostic errors, technical errors and problems of ACL graft integrations. Regarding surgical technique, we should answer certain questions about our choice of surgery, tunnel position, graft type, graft suture, tensioning the graft, and how we deal with certain incidents or intraoperative accidents. The purpose of this article is to review the current information and trends of ACL reconstruction, and presents some tips and tricks we use in our current practice.

The inferior medial genicular artery and its vascularization of the pes anserinus superficialis: A cadaveric study

BACKGROUND

A common method for reconstruction of the anterior cruciate ligament (ACL) is it's replacement by a free avascular graft, using the gracilis and/or semitendinosus tendons. These grafts pass a vulnerable phase in the ligamentization-process during the 1^st year after reconstruction. The aims of this study were first to evaluate the vascularization of the pes anserinus superficialis (PAS) by the inferior medial genicular artery (IMGA) and second to develop a pedunculated surgical technique for ACL reconstruction, to preserve a maximal amount of natural vascularization of the tendons inserting at the PAS.

MATERIALS AND METHODS

First, the vascularization of the PAS was assessed in 12 fresh-frozen lower extremities. The IMGA was identified at its origin at the popliteal artery and perfused with a methylene blue solution. Second, a pedunculated ACL reconstruction was performed in 5 fresh-frozen lower extremities under maintenance of the distal tendon insertion at PAS.

RESULTS

The PAS is a highly vascularized structure. Vessels originate from the IMGA, running along the three tendons of the PAS in the paratendinous tissue. Histologically intratendinous vessels exist; however, perfusion of the inserting tendons through intratendinous vessels was not proven macroscopically. The pedunculated grafts could be positioned and fixed successfully into the bone tunnels in all knees.

CONCLUSION

Although intratendinous vascularization of the tendons of the PAS via the IMGA was not proven, this study indicates a new possibility of ACL reconstruction. The described operation technique can be conducive to shorten the vulnerable phase of the graft-ligamentization after ACL reconstruction.

Reducing Intra-articular Hemarthrosis After Arthroscopic Anterior Cruciate Ligament Reconstruction by the Administration of Intravenous Tranexamic Acid: A Prospective, Randomized Controlled Trial

BACKGROUND

A significant proportion of surgeons use intra-articular drains after arthroscopic anterior cruciate ligament (ACL) reconstruction. Hemarthrosis and pain adversely affect the functional outcomes of ACL reconstruction in the early postoperative period.

PURPOSE

To evaluate the effects of administering tranexamic acid (TXA) to minimize knee joint hemarthrosis and associated pain.

STUDY DESIGN

Randomized controlled trial; Level of evidence, 1.

METHODS

A total of 105 patients who underwent arthroscopic ACL reconstruction were enrolled in this prospective, randomized, double-blind study. The patients who were randomized to the TXA group (n = 53) received intravenous TXA; the control group (n = 52) did not receive TXA. The anesthetist, surgeon, observer, and patients were blinded to the study groups (double-blinded). TXA was administered as a bolus dose of 15 mg/kg 10 minutes before the inflation of the tourniquet, and an intravenous infusion of 10 mg/kg/h was continued for 3 hours after completion of the operation. In the control group, an equal volume of placebo was administered at the same rate and by the same route. The volume of drained blood was measured 24 hours postoperatively. Pain was evaluated using a visual analog scale (VAS) at a consistent time in the evening of postoperative day 3 and postoperative weeks 2 and 3. The Lysholm knee scoring scale was used to record patient satisfaction and knee function during postoperative weeks 2 and 4.

RESULTS

Significant differences were observed between the volume of fluid drained (60 mL [TXA group] vs 150 mL [control group]; P < .001) (between-group difference [95% CI], -90 [-114.15 to -65.85]) and hemarthrosis grade in postoperative weeks 1 and 2. In addition, the pain outcome improved in the TXA group after day 3 (VAS score, 1.4) compared with that in the control group (VAS score, 2.9) (P < .001) (95% CI, -1.51 to -0.49). The VAS scores of the TXA group at the end of weeks 2 and 3 were also significantly lower than those in the control group (P < .001) (95% CI, -2.00 to -1.00). The median Lysholm score at the end of week 2 was 70 (range, 40-85) in the control group and 75 (range, 50-90) in the TXA group; at the end of week 4, the score was 75 (range, 50-85) in the control group and 80 (range, 70-85) in the TXA group. A significant difference in the Lysholm score was observed between the 2 groups (P < .001) (95% CIs, 0.08-9.92 and 4.00-10.00 for weeks 2 and 4, respectively). Although range of motion was similar between the groups at the end of week 4, the mean was 107.36° ± 8.36° in the TXA group and 103.65° ± 7.68° in the control group on postoperative day 2 (P = .020) (95% CI, 0.60-6.81). The mean hemarthrosis values at the end of weeks 1 and 2 were significantly lower in the TXA group than in the control group (P < .001), and the need for aspiration in the TXA group during the early postoperative period was significantly lower than in the control group (P < .001). There were no infections in either group, and no patient developed deep venous thrombosis by postoperative day 3.

CONCLUSION

The results of this prospective, randomized study show that TXA reduced the amount of postoperative hemarthrosis and decreased the need for aspiration of the knee after arthroscopic ACL reconstruction. Consequently, TXA reduced pain and improved range of motion of the knee in the early postoperative period without side effects.

What is the best candidate allograft for ACL reconstruction? An in vitro mechanical and histologic study in a canine model

The knee joint is generally characterized by very low friction and high wear resistance. Several previous studies have compared ACL with the commonly used allografts from tensile properties perspective. No study has reported about the graft tendons from a frictional perspective, which is an important parameter for ACL functional performance. Twenty hind legs were used to harvest FDP tendon, ACL, ACH, and patellar tendon. Samples were evaluated with surface friction testing, indentation testing for tendon compressive moduli, lubricin immunohistochemistry, and histologic analysis. Frictional force of FDP tendon and ACL was significantly less than that of patellar tendon and ACH at first and fifth cycles. At the tenth cycle, the FDP tendon, ACL, and ACH showed significantly less frictional force than patellar tendon; after 100 cycles, the FDP tendon and ACL showed significantly less frictional force than patellar tendon. The compressive moduli of the FDP tendon, ACL, and ACH were significantly greater than that of patellar tendon. Histologic results showed that FDP tendon and ACL had a smooth surface with a thin layer of epitenon cells; patellar tendon and ACH had a rough surface and a layer of paratenon. Lubricin was found on the surface and extracellular matrix of FDP tendon and ACL. There was only limited lubricin expression on the surface and extracellular matrix of the ACH and patellar tendon. The FDP tendon has friction force and lubricin expression similar to those of native ACL. However, patellar tendon and ACH show higher friction force and less lubricin expression than ACL.

Anterior cruciate ligament biomechanics during robotic and mechanical simulations of physiologic and clinical motion tasks: a systematic review and meta-analysis

Investigators use in vitro joint simulations to invasively study the biomechanical behaviors of the anterior cruciate ligament. The aims of these simulations are to replicate physiologic conditions, but multiple mechanisms can be used to drive in vitro motions, which may influence biomechanical outcomes. The objective of this review was to examine, summarize, and compare biomechanical evidence related to anterior cruciate ligament function from in vitro simulations of knee motion. A systematic review was conducted (2004 to 2013) in Scopus, PubMed/Medline, and SPORTDiscus to identify peer-reviewed studies that reported kinematic and kinetic outcomes from in vitro simulations of physiologic or clinical tasks at the knee. Inclusion criteria for relevant studies were articles published in English that reported on whole-ligament anterior cruciate ligament mechanics during the in vitro simulation of physiologic or clinical motions on cadaveric knees that were unaltered outside of the anterior-cruciate-ligament-intact, -deficient, and -reconstructed conditions. A meta-analysis was performed to synthesize biomechanical differences between the anterior-cruciate-ligament-intact and reconstructed conditions. 77 studies met our inclusion/exclusion criteria and were reviewed. Combined joint rotations have the greatest impact on anterior cruciate ligament loads, but the magnitude by which individual kinematic degrees of freedom contribute to ligament loading during in vitro simulations is technique-dependent. Biomechanical data collected in prospective, longitudinal studies corresponds better with robotic-manipulator simulations than mechanical-impact simulations. Robotic simulation indicated that the ability to restore intact anterior cruciate ligament mechanics with anterior cruciate ligament reconstructions was dependent on loading condition and degree of freedom examined.

The effect of notchplasty on tunnel widening in anterior cruciate ligament reconstruction

PURPOSE

To investigate changes in femoral tunnel diameter, dimension, and volume after anterior cruciate ligament reconstruction with notchplasty.

METHODS

Porcine knee specimens were divided into 2 groups of 10 specimens each. Group A did not receive notchplasty. A 2-mm notchplasty was conducted in group B. Seven-millimeter-diameter femoral tunnels were drilled and a doubled flexor digitorum profundus tendon was inserted and fixed with an EndoButton (Smith & Nephew, Andover, MA) in each knee specimen. Samples were mounted on a materials testing machine. Each group was preloaded at 10 N and subjected to 20 loading cycles (between 0 and 40 N), followed by 1,000 loading cycles in the elastic region (between 10 and 150 N). High-resolution computed tomography with 1.0-mm slices was conducted with all samples before and after testing. A 3-dimensional model was constructed to evaluate the degree of the tunnel change.

RESULTS

In group B the mean longest diameter and dimension of the femoral tunnel significantly increased after the test (P = .005 and P = .001, respectively). The volumetric loss of bony structure after the test in group B was significantly greater than that in group A (P = .039). Meanwhile, no significant difference was found before and after the test in terms of tunnel diameter, dimension, and volumetric loss around the tunnel in group A.

CONCLUSIONS

The intra-articular orifice of the femoral tunnel was enlarged after the uniaxial cyclic loading test after notchplasty. An enlarged tunnel orifice may lead to a discrepancy between the tunnel and the graft at the tunnel aperture.

CLINICAL RELEVANCE

The data may have an implication that suspensory fixation with a notchplasty has a negative effect on the full graft accommodation at the tunnel aperture. Aperture widening may affect graft positioning, leading to subtle changes in graft biomechanics and laxity.

Evaluation and Comparison of Femoral Tunnel Placement During Anterior Cruciate Ligament Reconstruction Using 3-Dimensional Computed Tomography: Effect of Notchplasty on Transtibial and Medial Portal Drilling

BACKGROUND

Advocates of medial portal drilling claim that the transtibial technique results in a more vertical positioning of the graft, which could lead to subsequent failure and/or a residual pivot shift on postoperative examination. However, advocates of transtibial drilling state that with appropriate placement and adequate notchplasty, their technique places the graft in a more anatomically correct position on the wall, negating the resultant potential for pivot shift and early postoperative failure.

HYPOTHESIS

Transtibial femoral drilling can adequately reproduce the femoral origin of the anterior cruciate ligament (ACL) and place the graft in an anatomical position equivalent to medial portal drilling.

STUDY DESIGN

Controlled laboratory study.

METHODS

Ten matched-pair cadaveric knees (N = 20) were scanned using computed tomography (CT), and 3-dimensional images of the native ACL origin were reconstructed. The matched pairs were then randomized into transtibial and medial portal groups. The femoral tunnel was drilled in each knee according to group. A bamboo skewer was placed in the femoral tunnel, and the knees underwent a second CT scan. Arthroscopic notchplasty was performed, and the femoral tunnels were redrilled. Radiographs confirmed placement, and the post-notchplasty tunnel was reamed with a 4-mm reamer. The knees underwent a third CT scan. CT scans compared femoral tunnel placement with the native ACL footprint before and after notchplasty.

RESULTS

The post-notchplasty transtibial group revealed an average of 68.3% coverage of the native ACL femoral origin. The medial portal group revealed an average of 60.8% coverage, with 1 instance of perforation of the posterior cortex. There were no instances of perforation in the transtibial group.

CONCLUSION

Both drilling techniques place the graft in an anatomically correct position.

CLINICAL RELEVANCE

Transtibial drilling of the femur can adequately place the entry tunnel at the origin of the ACL's native footprint.

Intercondylar roof impingement after anatomic double-bundle anterior cruciate ligament reconstruction in patients with knee hyperextension

BACKGROUND

Although an anatomically placed graft in anterior cruciate ligament (ACL) reconstruction is reported to have a low risk of roof impingement, which may cause deterioration of the graft or an extension deficit, the incidence of roof impingement by these grafts has not been evaluated in hyperextensible knees.

PURPOSE

To evaluate the incidence of roof impingement by the native ACL in hyperextensible knees and to examine the risk of roof impingement by anatomic placement of the ACL graft in hyperextensible knees.

STUDY DESIGN

Controlled laboratory study.

METHODS

Twelve patients were selected for a hyperextensible knee group (group A), defined as having hyperextension of the knee of greater than 10°. Twelve patients were recruited to a normal extension knee group (group B) with normal extension of the knee of less than 5° of hyperextension. Magnetic resonance imaging (MRI) scans of the knee positioned in 30° of flexion and full extension were acquired from all patients. The shape of the native ACL at full extension was compared between the groups. A 3-dimensional (3D) bone model was created from the acquired 2D MRI scans. A virtual anatomic double-bundle ACL reconstruction in each patient and a virtual anatomic single-bundle reconstruction in the patients in group A were performed using the 3D MRI bone models. The volume of the overlap between the graft and roof was calculated to evaluate graft impingement in each instance.

RESULTS

The MRI scans showed posterior bowing of the native ACL in the group A knees. The simulated double-bundle ACL reconstruction showed that the overlapped volume was significantly greater in patients in group A than in patients in group B (P < .05). However, the overlap of the simulated single-bundle ACL reconstruction was significantly less than for the double-bundle ACL reconstruction (P < .05).

CONCLUSION

To reduce the risk of roof impingement by the graft, single-bundle ACL reconstruction with the graft placed at the center of the footprint might be the better method for patients with a hyperextensible knee than an anatomic double-bundle ACL reconstruction.

CLINICAL RELEVANCE

It is recommended that surgeons cautiously consider roof impingement after anatomic double-bundle ACL reconstruction in patients with a hyperextensible knee.