The Kinematic Basis of ACL Reconstruction

Association between passing return-to-sport testing and re-injury risk in patients after anterior cruciate ligament reconstruction surgery: a systematic review and meta-analysis

Background

Inconsistent results have been obtained regarding the association between return-to-sport (RTS) testing and the risk of subsequent re-injury following anterior cruciate ligament reconstruction (ACLR). We therefore conducted a systematic review and meta-analysis to assess the potential association between passing of RTS and the risk of re-injury for patients after ACLR.

Methods

This meta-analysis was registered in INPLASY with the registration number INPLASY202360027. The electronic databases MedLine, EmBase, and the Cochrane library were systematically searched to identify eligible studies from their inception up to September 2023. The investigated outcomes included knee injury, secondary ACL, contralateral ACL injury, and graft rupture. The pooled odds ratios (ORs) and 95% confidence intervals (CIs) were calculated using the random-effects model.

Results

A total number of nine studies involving 1410 individuals were selected for the final quantitative analysis. We noted that passing RTS test was not associated with the risk of subsequent knee injury (OR: 0.95; 95% CI: 0.28-3.21; P = 0.929), secondary ACL injury (OR: 0.98; 95% CI: 0.55-1.75; P = 0.945), and contralateral ACL injury (OR: 1.53; 95% CI: 0.63-3.71; P = 0.347). However, the risk of graft rupture was significantly reduced (OR: 0.49; 95% CI: 0.33-0.75; P = 0.001).

Conclusions

This study found that passing RTS test was not associated with the risk of subsequent knee injury, secondary ACL injury, and contralateral ACL injury, while it was associated with a lower risk of graft rupture. Thus, it is recommended that patients after ACLR pass an RTS test in clinical settings.

ACLD patients exhibit additional knee kinematic asymmetries at the speed level of healthy subjects

Anterior cruciate ligament deficiency (ACLD) patients tend to walk slowly but try to catch up with the speed level of healthy subjects daily. Exploring the effects of the walking speed level of healthy subjects on the ACLD patients’ knee kinematics is important to improving non-operative treatments and delaying the progression of posttraumatic knee osteoarthritis. This study aimed to explore whether healthy controls’ walking speed level leads to additional knee kinematic asymmetries in patients with ACLD. 27 ACLD patients and 29 healthy controls were recruited for the study. The ACLD patients walked at two levels of walking speed, including self-selected and healthy controls’ walking speed levels. A three-dimensional gait analysis system was used to collect their knee kinematic data. ACLD patients exhibited more kinematic asymmetries when walking at healthy controls’ walking speed level than at their self-selected speeds. The kinematic asymmetries included increased posterior tibial translation (4.6 mm) and anteroposterior tibial ROM (3.9 mm), abduction angle (1.5°), and distal tibial translation (3.2 mm) asymmetries (p < 0.05). Our findings are meaningful for developing non-operative treatment strategies for patients with ACLD. To get fewer knee kinematic asymmetries, self-selected walking speed could be suggested for patients with ACLD daily rather than the speed levels of healthy subjects.

Increase in cartilage degeneration in all knee compartments after failed ACL reconstruction at 4 years of follow-up

Purpose

Degeneration of the cartilage after anterior cruciate ligament reconstruction (ACL-R) is known, and further deterioration can be expected in patients with tunnel malplacement or partial meniscal resection. It was hypothesized that there is a significant increase in cartilage degeneration after failed ACL-R.

Material and methods

Isolated ACL revision surgery was performed in 154 patients at an interval of 46 ± 33 months (5–175 months) between primary and revision surgery. Cartilage status at the medial, lateral femorotibial, and patellofemoral compartments were assessed arthroscopically during primary and revision ACL-R in accordance with the Outerbridge classification. Tunnel placement, roof angle, and tibial slope was measured using anteroposterior and lateral radiographic views.

Results

Cartilage degeneration increased significantly in the medial femorotibial compartment, followed by the lateral and patellofemoral compartments. There was a correlation between both cartilage degeneration in the patellofemoral compartment (PFC) (r_s = 0.28, p = 0.0012) and medial tibial plateau (R_s = 0.24, p = 0.003) in relation to the position of tibial tunnel in the frontal plane. Worsening of the cartilage status in the medial femorotibial compartment, either femoral or tibial, was correlated with the tibial aperture site in the lateral view (R_s = 0.28, p < 0.001). Cartilage degeneration in the lateral compartment of the knee, on both femoral or tibial side, was inversely correlated with the femoral roof angle (R_s = −0.1985, p = 0.02). Meniscal tears, either at the medial or lateral site or at both, were found in 93 patients (60%) during primary ACL-R and increased to 132 patients (86%) during revision ACL-R.

Discussion

Accelerated cartilage degeneration and high prevalence of meniscal lesions are seen in failed ACL-R. Tunnel placement showed significant impact on cartilage degeneration and may partially explain the increased risk of an inferior outcome when revision surgery is required after failed primary ACL-R.

Level of evidence: Level IV—retrospective cohort study.

Arthroscopic anterior cruciate ligament reconstruction is a reliable option to treat knee instability in patients over 50 years old

PURPOSE

To evaluate return to sport and clinical outcomes with at least 2 years followup after arthroscopic reconstruction ACL in population over 50 years-old.

METHODS

eighty-one patients aged 50 years or older underwent isolated, primary ACL reconstruction with hamstring autograft between 2014 and 2016. In all patients, a period of conservative treatment had failed (minimum 6 months), and they complained of functional instability and/or limitation during daily activity. Patients were assessed preoperatively and at the latest follow-up with a physical examination, return to sports activity, the Lysholm score, the International Knee Documentation Committee scoring system, the Knee injury and Osteoarthritis Outcome Score, and the Tegner activity scale. Data regarding complications and revision surgeries were collected at 2-year follow-up.

RESULTS

At the last follow-up, significant improvement in outcome scores from pre- to postoperative assessments was found. The mean overall IKDC score increased from a preoperative mean of 54.4-82.9 (p < 0.001). Mean preoperative Lysholm score increased from a preoperative mean of 67.4-90.4 (p < 0.001). The mean overall KOOS score increased from a preoperative mean (p < 0.001). Median preoperative Tegner score was 5 (range 2-8) and median postoperative score was 5 (range 1-7). 86% of patients returned to the sport, 51% to their preinjury sports level. Tegner score, before accident, was the only positive influencing factor a return to pre-injury level of the sport.

CONCLUSION

Arthroscopic reconstruction ACL in patients over 50 years-old resulted in excellent functional outcomes, with most patients returning to sport and at the same level they had before the injury.

LEVEL OF EVIDENCE

Level IV.

Return to Play and Long-term Participation in Pivoting Sports After Anterior Cruciate Ligament Reconstruction

BACKGROUND

Rupture of the anterior cruciate ligament (ACL) is a common and feared injury among athletes because of its potential effect on further sports participation. Reported rates of return to pivoting sports after ACL reconstruction (ACLR) vary in the literature, and the long-term consequences of returning have rarely been studied.

PURPOSE

To examine the rate and level of return to pivoting sports after ACLR, the duration of sports participation, and long-term consequences of returning to pivoting sports.

STUDY DESIGN

Cohort study; Level of evidence, 2.

METHODS

All primary ACLRs with a bone-patellar tendon-bone autograft between 1987 and 1994 (N = 234) in athletes participating in team handball, basketball, or soccer before injury were selected from a single-center quality database. A long-term evaluation (median, 25 years; range, 22-30 years) was performed using a questionnaire focusing on return to pivoting sports, the duration of sports activity after surgery, later contralateral ACL injuries, revision surgery, and knee replacement surgery. Participants were stratified into 2 groups depending on the time between injury and surgery (early, <24 months; late, ≥24 months).

RESULTS

A total of 93% of patients (n = 217) responded to the questionnaire. Although 83% of patients returned to pivoting sports after early ACLR, only 53% returned to preinjury level. Similar return-to-sport rates were observed in males and females (P > .05), but males had longer sports careers (median, 10 years; range, 1-23 years) than females (median, 4 years; range, 1-25 years; P < .001). The incidence of contralateral ACL injuries was 28% among athletes who returned to sports versus 4% among athletes who did not return (P = .017) after early ACLR. The pooled reinjury rate after return to preinjury level of sports was 41% (30%, contralateral injuries; 11%, revision surgery). The incidence of contralateral ACL injuries was 32% among females versus 23% among males (P > .05) and, for revision surgery, was 12% among females versus 7% among males (P > .05) after returning to sports. Having a late ACLR was associated with an increased risk of knee replacement surgery (9% vs 3%; P = .049) when compared with having an early ACLR.

CONCLUSION

ACLR does not necessarily enable a return to preinjury sports participation. By returning to pivoting sports after ACLR, athletes are also facing a high risk of contralateral ACL injuries. Long-term evaluations in risk assessments after ACLR are important, as a significant number of subsequent ACL injuries occur later than the routine follow-up.

Reliability, discriminant validity and sex comparisons of dynamic postural stability during a landing task designed to challenge transverse plane knee stability

Internal and external rotational knee stability is essential for sports performance and excessive rotation can lead to injury but is rarely assessed in injury risk analysis. The objectives of this study were to determine the between-session reliability, discriminant validity and potential sex differences of a dynamic postural stability (DPS) assessment that challenges transverse plane knee stability. Thirty-six individuals (21.7 ± 2.6 years) including 19 females (20.8 ± 1.3 years) and 17 males (22.6 ± 3.4 years) participated. We measured DPS during rotational jump tasks (RJT) over 2 test sessions utilising a force plate. Kinematic (motion analysis) and electromyographic measures were compared to a traditional anterior-posterior jump task (APJT) to assess the discriminant validity and comparisons were performed between sexes. The intraclass correlation coefficients were between 0.67 and 0.86. Significant differences in transverse rotation angle at initial contact transverse rotational velocity of the knee were observed between the 2 different RJT and between the RJT and the traditional APJT. No sex differences were observed. The new assessment had good between-session reliability and offers a different challenge than a traditional jump task. This RJT may offer a novel assessment of knee joint rotational stability in conjunction with traditional measures.

Altered kinematics after anterior cruciate ligament reconstruction, and their role in the prevention of osteoarthritis

Background/Aims:

Anterior cruciate ligament injury is common, and anterior cruciate ligament reconstruction has become the standard of care that aims to restore knee stability, return to activity, and prevent secondary injury.

Methods:

A literature review was carried out using PubMed and Science Direct databases from 1998 through 2017. Search terms included: anterior cruciate ligament reconstruction and knee osteoarthritis; kinematics after anterior cruciate ligament reconstruction; and prevention of knee osteoarthritis. A total of 356 studies matched the search terms. After removing duplicates and any studies that were not relevant, 73 studies remained.

Findings:

Individuals usually have impaired neuromuscular control after reconstruction, and abnormal biomechanical patterns may lead to loading of cartilage areas that are not commonly loaded and that, longitudinally, can lead to osteoarthritis. The knee adduction moment indicates loading of the knee joint and has been associated with the development of osteoarthritis and altered gait mechanics have also been implicated in the increased rate of osteoarthritis after anterior cruciate ligament reconstruction, including differences in tibial rotation during walking. Furthermore, altered ankle joint mechanics may be the result of deviations in ankle joint alignment secondary to the structural changes at the knee. It is clear that abnormal mechanical stimulation may cause dysfunction of articular chondrocytes and breakdown of cartilage extracellular matrix, leading to articular cartilage degradation and chondrocyte death. The affected joint will progress to post-traumatic osteoarthritis.

Conclusions:

The restoration of normal knee anatomy and mechanics, such as returning the joint to normal function, improving muscle strength, functional movement prevention programmes, restoring gait symmetry and weight management are recommended.

Longitudinal analysis of tibiofemoral cartilage contact area and position in ACL reconstructed patients

Patients who have suffered ACL injury are more likely to develop early onset post-traumatic osteoarthritis despite reconstruction. The purpose of our study was to evaluate the longitudinal changes in the tibiofemoral cartilage contact area size and location after ACL injury and reconstruction. Thirty-one patients with isolated unilateral ACL injury were followed with T₂ weighted Fast Spin Echo, T_1ρ and T₂ MRI at baseline prior to reconstruction, and 6 months, 1 year, and 2 years after surgery. Areas were delineated in FSE images with an in-house Matlab program using a spline-based semi-automated segmentation algorithm. Tibiofemoral contact area and centroid position along the anterior-posterior axis were calculated along with T_1ρ and T₂ relaxation times on both the injured and non-injured knees. At baseline, the injured knees had significantly smaller and more posteriorly positioned contact areas on the medial tibial surface compared to corresponding healthy knees. These differences persisted 6 months after reconstruction. Moreover, subjects with more anterior medial centroid positions at 6 months had elevated T_1ρ and T₂ measures in the posterior medial tibial plateau at 1 year. Changes in contact area and centroid position after ACL injury and reconstruction may characterize some of the mechanical factors contributing to post-traumatic osteoarthritis. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:2718-2727, 2018.

PATIENT-SPECIFIC AND SURGERY-SPECIFIC FACTORS THAT AFFECT RETURN TO SPORT AFTER ACL RECONSTRUCTION

CONTEXT

Anterior cruciate ligament (ACL) reconstruction is frequently performed to allow individuals to return to their pre-injury levels of sports participation, however, return to pre-injury level of sport is poor and re-injury rates are unacceptably high. Re-injury is likely associated with the timeframe and guidelines for return to sport (RTS). It is imperative for clinicians to recognize risk factors for re-injury and to ensure that modifiable risk factors are addressed prior to RTS. The purpose of this commentary is to summarize the current literature on the outcomes following return to sport after ACL reconstruction and to outline the biologic and patient-specific factors that should be considered when counseling an athlete on their progression through rehabilitation.

EVIDENCE ACQUISITION

A comprehensive literature search was performed to identify RTS criteria and RTS rates after ACL reconstruction with consideration paid to graft healing, anatomic reconstruction, and risk factors for re-injury and revision. Results were screened for relevant original research articles and review articles, from which results were summarized.

STUDY DESIGN

Clinical Review of the Literature.

RESULTS

Variable RTS rates are presented in the literature due to variable definitions of RTS ranging from a high threshold (return to competition) to low threshold (physician clearance for return to play). Re-injury and contralateral injury rates are greater than the risk for primary ACL injury, which may be related to insufficient RTS guidelines based on time from surgery, which do not allow for proper healing or resolution of post-operative impairments and elimination of risk factors associated with both primary and secondary ACL injuries.

CONCLUSIONS

RTS rates to pre-injury level of activity after ACLR are poor and the risk for graft injury or contralateral injury requiring an additional surgery is substantial. Resolving impairments while eliminating movement patterns associated with injury and allowing sufficient time for graft healing likely gives the athlete the best chance to RTS without further injury. Additional research is needed to identify objective imaging and functional testing criteria to improve clinical decision making for RTS after ACLR.

LEVEL OF EVIDENCE

Level 5.

Complex function of the knee joint: the current understanding of the knee

Since the early years of orthopaedics, it is a well-known fact that anatomy follows function. During the evolution of mankind, the knee has been optimally adapted to the forces and loads acting at and through the knee joint. However, anatomy of the knee joint is variable and the only constant is its complex function. In contrast to the time of open surgery, nowadays the majority of reconstructive knee surgery is done arthroscopically. Keyhole surgery is less invasive, but on the backside, the knee surgeon lacks daily visualisation of the complex open anatomy. As open anatomical knowledge is less present in our daily practice, it is even more important to highlight this complex anatomy and function of the knee. It is the purpose of this review to perform a systematic review of knee anatomy, highlight the complex function of the knee joint and present an overview about recent and current knowledge about knee function. Level of evidence Systematic review, Level IV.

Is the native ACL insertion site "completely restored" using an individualized approach to single-bundle ACL-R?

PURPOSE

The goal of individualized anatomic anterior cruciate ligament reconstruction (ACL-R) is to reproduce each patient's native insertion site as closely as possible. The amount of the native insertion site that is recreated by the tunnel aperture area is currently unknown, as are the implications of the degree of coverage. As such, the goals of this study are to determine whether individualized anatomic ACL-R techniques can maximally fill the native insertion site and to attempt to establish a crude measure to evaluate the percentage of reconstructed area as a first step towards elucidating the implications of complete footprint restoration.

METHODS

This is a prospective pilot study of 45 patients who underwent primary single-bundle anatomic ACL-R from May 2011 to April 2012. Length and width of the native insertion site were measured intraoperatively. Using published guidelines, reconstruction technique and graft choice were determined to maximize the percentage of reconstructed area. Native femoral and tibial insertion site area and femoral tunnel aperture area were calculated using the formula for area of an ellipse. On the tibial side, tunnel aperture area was calculated with respect to drill diameter and drill guide angle. Percentage of reconstructed area was calculated by dividing total tunnel aperture area by the native insertion site area.

RESULTS

The mean areas for the native femoral and tibial insertion sites were 83 ± 20 and 125 ± 20 mm(2), respectively. The mean tunnel aperture area for the femoral side was 65 ± 17, and 86 ± 17 mm(2) for the tibial tunnel aperture area. On average, percentage of reconstructed area was 79 ± 13 % for the femoral side, and 70 ± 12 % for the tibial side.

CONCLUSION

Anatomic ACL-R does not restore the native insertion site in its entirety. Percentage of reconstructed area serves as a rudimentary tool for evaluating the degree of native insertion site coverage using current individualized anatomic techniques and provides a starting point from which to evaluate the clinical significance of complete footprint restoration.

LEVEL OF EVIDENCE

IV.

Mesenchymal stem cells reside in anterior cruciate ligament remnants in situ

PURPOSE

It has been reported that the anterior cruciate ligament (ACL) has certain self-healing ability after acute injury or with primary suture repair. Many studies have confirmed that a remnant preservation technique with ACL reconstruction contributes to biological augmentation for ACL healing. However, it remains unclear whether mesenchymal stem cells (MSC) reside in ACL remnants in situ. The aim of this study was to investigate the methods of culture and identification of MSC derived from the remnants of ACL rupture patients and to analyse these MSC's properties.

METHODS

The cells of ACL remnants from the ACL rupture patients were isolated by the methods of enzymatic digestion and cultured in vitro to the third passage under the microscope to observe their morphology and growth status. The third passage of isolated cells was analysed for the identification of immunophenotype, osteogenic, adipogenic and chondrogenic differentiation.

RESULTS

On the third to fifth days of in vitro culture, a few cells of long fusiform shape appeared and were adherent to the plastic walls. On the sixth to ninth days, cells clustered and colonies were observed. The third passage cells showed uniform cell morphology and good proliferation, with appearance of the typical surface markers of MSC, CD29, CD44, CD90 and CD105. The surface markers of CD34 and CD45 of haematopoietic stem cells were not expressed. Under appropriate conditions of in vitro culture, isolated cells could be differentiated into osteoblasts that deposit mineralised matrix and express early osteogenic markers, adipocytes that accumulate lipid droplets in cytoplasm and chondrocytes that secrete chondrogenic-specific matrix aggrecan and collagen II. Real-time polymerase chain reaction (PCR) analysis demonstrated that the specific mRNA expression of osteogenesis, adipogenesis and chondrogenesis increased significantly compared with the control groups at day zero.

CONCLUSIONS

Stem cells derived in situ from the human ACL stump were successfully isolated and characterised. Those isolated cells were identified as MSC according to their adherent ability, morphology, surface markers and multilineage differentiation potential. MSC derived from ACL remnants could be a potential source of seeding cells for ligament regeneration.

Infrared assessment of knee instability in ACL deficient patients

PURPOSE

Previous clinical studies have shown that anterior cruciate ligament (ACL) ruptures require reconstructive surgery. The main goal of this study is an objective test definition for unstable knee diagnosis based on real measurements by using infrared cameras and adequate software.

METHODS

In the study of gait analysis 35 males with deficient ACL's participated. Pathological parameters for anterior posterior translation (APT) and internal external rotation (IER) and their values of kinematic data were obtained from a gait analysis 3D system. Movement curves were obtained by recording the position of fluorescent markers over time. A machine learning algorithm was developed in order to support decisions on the severity of the ACL injury and its corresponding deficiency. The algorithm was based on logistic regression.

RESULTS

The value of APT, designated as exponentiation of the Ө coefficient (Exp (Ө)) of APT, showed that the likelihood of ACL-deficient knee occurrence due to higher values of APT is 1.1758 (95 % CI) times more frequent than that of the patients with lower values of APT. The value of IER, designated as Exp (Ө) of IER, showed that the patients with higher values of IER present 2.2516 (95 % CI) times higher values of ACL-deficient knee frequency than those with lower values.

CONCLUSION

This study showed that the creation of ordered pairs of pathological parameters gives a wider picture of ACL deficiency and that such an algorithm may improve both examination and treatment of patients.

Rigorous geometric self-calibrating bundle adjustment for a dual fluoroscopic imaging system

High-speed dual fluoroscopy is a noninvasive imaging technology for three-dimensional skeletal kinematics analysis that finds numerous biomechanical applications. Accurate reconstruction of bone translations and rotations from dual-fluoroscopic data requires accurate calibration of the imaging geometry and the many imaging distortions that corrupt the data. Direct linear transformation methods are commonly applied for performing calibration using a two-step process that suffers from a number of potential shortcomings including that each X-ray source and corresponding camera must be calibrated separately. Consequently, the true imaging set-up and the constraints it presents are not incorporated during calibration. A method to overcome such drawbacks is the single-step self-calibrating bundle adjustment method. This procedure, based on the collinearity principle augmented with imaging distortion models and geometric constraints, has been developed and is reported herein. Its efficacy is shown with a carefully controlled experiment comprising 300 image pairs with 48 507 image points. Application of all geometric constraints and a 31 parameter distortion model resulted in up to 91% improvement in terms of precision (model fit) and up to 71% improvement in terms of 3-D point reconstruction accuracy (0.3-0.4 mm). The accuracy of distance reconstruction was improved from 0.3±2.0 mm to 0.2 ±1.1 mm and angle reconstruction accuracy was improved from -0.03±0.55(°) to 0.01±0.06(°). Such positioning accuracy will allow for the accurate quantification of in vivo arthrokinematics crucial for skeletal biomechanics investigations.

Prevention and screening programs for anterior cruciate ligament injuries in young athletes: a cost-effectiveness analysis

BACKGROUND

Anterior cruciate ligament (ACL) injuries are common among young athletes. Biomechanical studies have led to the development of training programs to improve neuromuscular control and reduce ACL injury rates as well as screening tools to identify athletes at higher risk for ACL injury. The purpose of this study was to evaluate the cost-effectiveness of these training methods and screening strategies for preventing ACL injuries.

METHODS

A decision-analysis model was created to evaluate three strategies for a population of young athletes participating in organized sports: (1) no training or screening, (2) universal neuromuscular training, and (3) universal screening, with neuromuscular training for identified high-risk athletes only. Risk of injury, risk reduction from training, and sensitivity and specificity of screening were based on published data from clinical trials. Costs of training and screening programs were estimated on the basis of the literature. Sensitivity analyses were performed on key model parameters to evaluate their effect on base case conclusions.

RESULTS

Universal neuromuscular training of all athletes was the dominant strategy, with better outcomes and lower costs compared with screening. On average, the implementation of a universal training program would save $100 per player per season, and would reduce the incidence of ACL injury from 3% to 1.1% per season. Screening was not cost-effective within the range of reported sensitivity and specificity values.

CONCLUSIONS AND CLINICAL RELEVANCE

Given its low cost and ease of implementation, neuromuscular training of all young athletes represents a cost-effective strategy for reducing costs and morbidity from ACL injuries. While continued innovations on inexpensive and accurate screening methods to identify high-risk athletes remain of interest, improving existing training protocols and implementing neuromuscular training into routine training for all young athletes is warranted.

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.

A Preliminary In Vivo Assessment of Anterior Cruciate Ligament-Deficient Knee Kinematics With the KneeM Device: A New Method to Assess Rotatory Laxity Using Open MRI

BACKGROUND

Methods of objectively measuring rotational knee laxity are either experimental or difficult to use in daily practice. A new method has been developed to quantitatively assess rotatory laxity using an open MRI system and new tool, the KneeM device.

PURPOSE/HYPOTHESIS

To perform a preliminary evaluation of a novel knee rotation measurement device to assess knee kinematics during flexion in an MRI field, in both anterior cruciate ligament (ACL)-deficient and healthy contralateral knees. The hypothesis was that the KneeM device would allow in vivo reproduction and analysis of knee kinematics during flexion in healthy and ACL-deficient knees.

STUDY DESIGN

Controlled laboratory study.

METHODS

Ten subjects (7 men and 3 women; mean age ± standard deviation, 32.3 ± 9.4 years) with ACL-deficient knees and contralateral uninjured knees participated in the study. An open MRI was performed with the KneeM device at a mean 4.9 months (range, 3.0-7 months) after ACL injury. The device exerted on the knee an anterior drawer force of 100 N, with an internal rotation of 20°, through the range of flexion (0°, 20°, 40°, and 60°). Both ACL-deficient and healthy contralateral knees were analyzed using the Iwaki method.

RESULTS

There was no statistical difference of anterior translation in the medial compartment between intact and ACL-deficient knees at all degrees of flexion. However, significant differences in the anterior translation of the lateral compartment were observed between ACL-deficient and intact contralateral knees at 0° and 20° of flexion (P = .005 and P = .002, respectively). Between 20° and 40°, the lateral plateau of ACL-deficient knees translated 7.7 mm posteriorly, whereas the medial compartment remained stable, reflecting a sudden external rotation of the lateral plateau under the femoral condyle.

CONCLUSION

This preliminary study suggests that measurement of tibiofemoral movements in both compartments during flexion using the KneeM device was useful for quantifying rotatory laxity in ACL-deficient knees. Moreover, this device seemed to allow a "mechanized pivot shift" and allowed reproduction of the "pivot" phase in the MRI field between 20° and 40° of flexion.

CLINICAL RELEVANCE

This device could be used for diagnostic purposes or to investigate the outcomes of ACL reconstructions.

Correlation between femoral tunnel length and tunnel position in ACL reconstruction

BACKGROUND

The position of the femoral tunnel affects the osseous geometry available for drilling during anterior cruciate ligament (ACL) reconstruction. The length of the tunnel changes with changes in the tunnel position and may have implications for femoral fixation.

METHODS

Forty-seven patients with a single-bundle ACL reconstruction underwent computed tomography (CT) evaluation to generate three-dimensional (3D) CT bone models. With use of a previously described anatomic coordinate system, the center of the femoral tunnel was quantified in the posterior-anterior and proximal-distal dimensions on 3D CT. Tunnel length was defined as the distance between the centers of the intra-articular and extra-articular tunnel apertures. The reconstructed knees were dichotomized by anatomy and technique into anatomic (n = 20) and nonanatomic (n = 27) groups as well as according to whether they had undergone medial portal drilling (n = 20) or transtibial drilling (n = 27) for analysis. In addition, a review of the literature on the relationship between tunnel length and tendon-to-bone healing was performed.

RESULTS

Femoral tunnels drilled with nonanatomic footprints were longer (mean [and standard deviation], 43.6 ± 8.5 mm; range, 28.2 to 60.7 mm) than tunnels drilled with anatomic footprints (31.0 ± 6.3 mm; 21.2 to 42.5 mm) (p &lt; 0.001). Tunnels drilled transtibially (44.4 ± 7.6 mm; 32.5 to 60.7 mm) were significantly longer than tunnels drilled through the medial portal (29.8 ± 5.0 mm; 21.2 to 40.3 mm) (p &lt; 0.001). There was a strong correlation between tunnel length and posterior-anterior femoral tunnel position (r = 0.78, p &lt; 0.05), with more anterior tunnel positioning associated with greater tunnel length. There was no correlation between posterior-distal femoral tunnel position and tunnel length (r = -0.05; p = 0.74). There was no consensus in the literature regarding adequate tunnel length for biologic fixation.

CONCLUSIONS

Femoral tunnels drilled with anatomic footprints had sufficient length for adequate femoral fixation. Femoral tunnels positioned anterior to the native insertion of the ACL were longer than those in anatomic position.

CLINICAL RELEVANCE

The results of this study can help the surgeon to consider the relationship between tunnel position and subsequent tunnel length in ACL reconstruction.

Long-term results after reconstruction of the ACL with hamstrings autograft and transtibial femoral drilling

PURPOSE

To evaluate the long-term clinical, patient-reported and radiological outcome of patients reconstructed for anterior cruciate ligament (ACL) insufficiency. We wanted to examine the relationship between clinical findings and patient-reported scores.

METHODS

The 96 first successive patients that underwent ACL reconstruction using transtibial technique, hamstrings autograft and tunnel placement ad modum Howell were evaluated 10 years post-operatively. Subjective outcomes were Lysholm score, IKDC 2000 subjective score and Tegner activity scale. The clinical examination included evaluation of rotational and sagittal laxity. Evaluation of osteoarthritis was done radiologically.

RESULTS

Eighty-three patients (86%) were available for follow-up at mean 10.2 years post-operatively. Three patients had revision ACL surgery prior to the 10-year evaluation. The mean Lysholm score, subjective IKDC 2000 score and Tegner activity scale were 89 (SD 13), 83 (SD 15) and 5 (range, 3-9), respectively. Six patients (8%) had moderate or severe osteoarthritis. Eighty-six per cent of patients had normal or near-normal anterior-posterior ACL laxity. Twenty per cent of patients had positive pivot shift and 42 % had a pivot glide. The former group had a significant lower Lysholm score compared to the rest of the patients.

CONCLUSIONS

Although the mean Lysholm score was classified as good (89) at the 10-year follow-up, a positive pivot shift was found in 20% of these patients. Compared to patients with normal rotational laxity or pivot glide, this patient group reported significant lower subjective satisfaction at the long-term follow-up.

LEVEL OF EVIDENCE

Case series, level IV.

There is significant load sharing and physical interaction between the anteromedial and posterolateral bundles of the ovine ACL under anterior tibial loads

INTRODUCTION

The ovine stifle joint is an ideal preclinical model to test the ability of double-bundle reconstruction techniques in providing superior joint stability and less osteoarthritis (OA) compared with single-bundle techniques. However, knowledge of the normal ovine ACL and more specifically the load sharing and physical interaction between the two main bundles of the ovine ACL is currently limited.

METHODS

Six ovine stifle joints were tested using a robotic testing system. Each joint was cyclically loaded to 200N in the anterior tibial direction between 30° and 90° flexion and the force-displacement data were recorded for both the intact ACL, and when the anteromedial (AM, n=3) or the posterolateral bundle (PL, n=3) was transected.

RESULTS

The load shared by the AM bundle increased from 30° to 75° of flexion at all loading levels (25-200N); whereas, the load shared by the PL bundle decreased between full extension and mid flexion (60°) and then increased again. The load borne by the AM bundle did not change in response to increasing Anterior Tibial Loads (ATL) at each flexion angle, in contrast to the PL bundle (P=0.004). Physical interaction between bundles was greatest at 60° and under 50N ATL.

CONCLUSION

These data will help create double-bundle ACL reconstructions in sheep which are functionally similar to intact native ACL. In turn, this model can be used to examine the success of anatomically accurate double-bundle reconstructions to prevent the development of OA.

LEVEL OF EVIDENCE

III.

Abnormal tibiofemoral kinematics following ACL reconstruction are associated with early cartilage matrix degeneration measured by MRI T1rho

PURPOSE

Altered kinematics following ACL-reconstruction may be a cause of post-traumatic osteoarthritis. T(1ρ) MRI is a technique that detects early cartilage matrix degeneration. Our study aimed to evaluate kinematics following ACL-reconstruction, cartilage health (using T(1ρ) MRI), and assess whether altered kinematics following ACL-reconstruction are associated with early cartilage degeneration.

METHODS

Eleven patients (average age: 33 ± 9 years) underwent 3T MRI 18 ± 5 months following ACL-reconstruction. Images were obtained at extension and 30° flexion under simulated loading (125 N). Tibial rotation (TR) and anterior tibial translation (ATT) between flexion and extension, and T(1ρ) relaxation times of the knee cartilage were analyzed. Cartilage was divided into five compartments: medial and lateral femoral condyles (MFC/LFC), medial and lateral tibias (MT/LT), and patella. A sub-analysis of the femoral weight-bearing (wb) regions was also performed. Patients were categorized as having "abnormal" or "restored" ATT and TR, and T(1ρ) percentage increase was compared between these two groups of patients.

RESULTS

As a group, there were no significant differences between ACL-reconstructed and contralateral knee kinematics, however, there were individual variations. T(1ρ) relaxation times of the MFC and MFC-wb region were elevated (p ≤ 0.05) in the ACL-reconstructed knees compared to the uninjured contralateral knees. There were increases (p ≤ 0.05) in the MFC-wb, MT, patella and overall average cartilage T(1ρ) values of the "abnormal" ATT group compared to "restored" ATT group. The percentage increase in the T(1ρ) relaxation time in the MFC-wb cartilage approached significance (p=0.08) in the "abnormal" versus "restored" TR patients.

CONCLUSIONS

Abnormal kinematics following ACL-reconstruction appear to lead to cartilage degeneration, particularly in the medial compartment.

Measurement of tibiofemoral kinematics using highly accelerated 3D radial sampling

This study investigated the use of dynamic, volumetric MRI to measure 3D skeletal motion. Ten healthy subjects were positioned on a MR-compatible knee loading device and instructed to harmonically flex and extend their knee at 0.5 Hz. The device induced active quadriceps loading with knee flexion, similar to the load acceptance phase of gait. Volumetric images were continuously acquired for 5 min using a 3D cine spoiled gradient-echo sequence in conjunction with vastly under-sampled isotropic projection reconstruction. Knee angle was simultaneously monitored and used retrospectively to sort images into 60 frames over the motion cycle. High-resolution static knee images were acquired and segmented to create subject-specific models of the femur and tibia. At each time frame, bone positions and orientations were determined by automatically registering the skeletal models to the dynamic images. Three-dimensional tibiofemoral translations and rotations were consistent across healthy subjects. Internal tibia rotations of 7.8±3.5° were present with 35.8±3.8° of knee flexion, a pattern consistent with knee kinematic measures during walking. We conclude that vastly under-sampled isotropic projection reconstruction imaging is a promising approach for noninvasively measuring 3D joint kinematics, which may be useful for assessing cartilage contact and investigating the causes and treatment of joint abnormalities.

The role of static and dynamic rotatory laxity testing in evaluating ACL injury

In this article, we discuss current topics for rotatory knee laxity. All tests for knee laxity have a value. Static knee laxity tests reveal information for each individual patient's laxity status, especially compared to the contralateral side. Static knee laxity tests are simple to do, and some of them are instrumented, therefore quantifiable. Dynamic knee laxity tests are more complex. Dynamic stereo radiography (DSX) is considered the gold standard. Utilizing DSX, information can be gained on 3-D kinematics, functional joint space, and joint contact patterns. The disadvantage is that DSX is expensive and can only be performed in a laboratory environment. The pivot shift test is a unique test, because it is dynamic and easily performed in the office. However, it is subjective and only recently quantifiable. Future endeavors will attempt to improve the value of the pivot shift test by standardizing the test and improving measurement technologies, while keeping the pivot shift test simple and non-invasive.

Rotatory knee laxity tests and the pivot shift as tools for ACL treatment algorithm

The goal of anterior cruciate ligament (ACL) reconstruction surgery is to eliminate the pivot shift phenomenon. Different injury mechanisms and injury patterns may lead to specific knee laxity patterns. Computer navigation is helpful for the surgeon during examination under anesthesia. Surgical treatment may have to be altered if high-grade laxity is detected preoperatively for example by utilizing a computer navigation that is a helpful adjunct for surgeons during examination under anesthesia. A typical case for revision ACL reconstruction is presented. This article describes several techniques of laxity assessments. Based on the type and degree of pathologic laxity, a treatment algorithm has been developed.

LEVEL OF EVIDENCE

V.

Anatomic anterior cruciate ligament reconstruction utilizing the double-bundle technique

The goal of every orthopaedic surgeon should be to restore anatomy as close as possible to normal. Intense research on reconstruction of the anterior cruciate ligament (ACL) and an advancing knowledge of the anatomy and function of the 2 primary bundles of the ACL have led to techniques of ACL reconstruction that more closely restore normal anatomy. Restoring the ACL footprint is one of the most important goals of the surgery, and the choice between anatomic single-bundle and double-bundle ACL reconstruction is determined by the anatomical features of each patient. After reconstruction, the graft undergoes a complex, lengthy process of remodeling; therefore, inappropriate (early), aggressive rehabilitation can lead to graft failure and compromise the patient's outcome. The purpose of this article is to provide an overview of the anatomy and function of the ACL, the methods for anatomic single-bundle and double-bundle ACL reconstruction, and our recommendations for postoperative rehabilitation.

Anatomic double-bundle and over-the-top single-bundle with additional extra-articular tenodesis: an in vivo quantitative assessment of knee laxity in two different ACL reconstructions

PURPOSE

Combinations of intra- and extra-articular procedures have been proposed for anterior cruciate ligament reconstruction with the aim of achieving an optimal control of translational and rotational knee laxities. Recently, the need for better reproducing the structural and functional behavior of the native anterior cruciate ligament led to the definition of anatomic double-bundle surgical approach. This study aimed to quantitatively verify whether the in vivo static and dynamic behavior obtained using over-the-top single-bundle with extra-articular tenodesis reconstruction was comparable to the results achieved by anatomic double-bundle approach.

METHODS

Thirty-five consecutive patients, with an isolated anterior cruciate ligament injury, were included in the study. Standard clinical laxities and pivot-shift test were quantified before and after anterior cruciate ligament reconstruction by means of a surgical navigation system dedicated to kinematic assessment; displacements of medial and lateral compartment during stress tests were also analyzed.

RESULTS

Single-bundle with extra-articular tenodesis approach presented statistically better laxity reduction in varus/valgus stress test at full extension and in internal/external rotation at 90° of flexion; lateral plasty controlled better the lateral compartment during drawer test and varus/valgus stress test both at 0° and 30° of flexion and both the compartments during internal/external rotation at 90° of flexion. On the other hand, pivot-shift phenomenon was better controlled by anatomic double-bundle reconstruction.

CONCLUSIONS

Both the reconstructions worked similarly for static knee laxity. The extra-articular procedure played an important role in better constraining the displacement of lateral tibial compartment, whereas the anatomic double-bundle reconstruction better restored the dynamic behavior of knee joint highlighted under pivot-shift stress test.

STUDY DESIGN

Case series.

Measurement of rotational laxity of the knee: in vitro comparison of accuracy between the tibia, overlying skin, and foot

BACKGROUND

Posterolateral corner (PLC) injuries are difficult to diagnose and cause significant morbidity. The ideal method for the dial test and its accuracy remain unclear.

PURPOSE

This study compares the accuracy of measuring tibial external rotation at the skeletal level to measuring the patella-tubercle angle (PTA) and the thigh-foot angle (TFA) in the supine position to assess the most accurate method to measure rotation during the dial test.

STUDY DESIGN

Controlled laboratory study.

METHODS

Measurements were compared simultaneously using rotational goniometers at a cutaneous splint over the tibia, at a foot splint, and directly from the tibial skeleton. Six lower limbs were used. The femur was held rigidly and the knee tested at 90° and 30° of flexion. External rotation torque up to 8 N·m was applied through the foot splint, and the rotations were measured by 2 testers.

RESULTS

Measurements at the tibial splint and directly on the tibia showed significant correlation at both knee flexion angles. The mean tibial external rotation was 24° at 90° of flexion and 26° at 30° of flexion (P < .05). The soft tissue effect caused the tibial splint to overestimate rotations by a mean of 6° and 9° at 90° and 30° of flexion, respectively. Foot splint measurements did not correlate significantly with tibial rotation, overestimating rotations by a mean of 103%. Intratester and intertester intraclass correlations were significant for the skin-mounted tibial splint measurements at both flexion angles but not for foot splint measurements at either flexion angles.

CONCLUSION

Rotation of the foot did not accurately represent the tibial external rotation at the knee, which could be measured more accurately by an instrument resting on the skin via a molded tibial splint. These results suggest that the PTA, and not the TFA, should be used in the dial test. This would support the use of the supine position during the dial test.

CLINICAL RELEVANCE

The dial test is a commonly used method for diagnosing PLC injuries. This study helps to identify the ideal position and measuring points to use for this test; measurements based on the tibia were more accurate than those that used rotation of the foot.

Predictors of radiographic knee osteoarthritis after anterior cruciate ligament reconstruction

BACKGROUND

Evidence suggests that single-bundle anterior cruciate ligament (ACL) reconstruction does not reliably prevent the development of knee osteoarthritis (OA).

PURPOSE

This study was conducted to determine the overall prevalence of and risk factors for the development of radiographic knee OA after single-bundle ACL reconstruction.

STUDY DESIGN

Case control study; Level of evidence, 3.

METHODS

There were 249 individuals who had undergone primary single-bundle ACL reconstruction included in this retrospective cohort study. Follow-up radiographs were scored by a single orthopaedic surgery sports medicine fellow using the Kellgren-Lawrence (KL) scale to determine the degree of OA in the medial, lateral, and patellofemoral compartments. Radiographic OA of the involved knee was considered to be present if, compared with the noninvolved knee, there was at least a 2-grade difference in the KL score in at least 1 compartment or a 1-grade difference in at least 2 compartments. Predictors of OA that were explored included patient age, sex, body mass index (BMI), smoking status activity level, meniscectomy before or concurrent with ACL reconstruction, chondral injury present at the time of ACL reconstruction, graft type and source, tibial and femoral tunnel positions, need for revision, and length of follow-up. Univariable and stepwise multivariable logistic regressions were used to identify factors that were associated with radiographic knee OA.

RESULTS

Thirty-nine percent of the patients had radiographic OA an average of 7.8 years after surgery. Female sex, BMI, time from injury to surgery, medial and patellofemoral compartment chondrosis, prior medial or lateral meniscectomy, concurrent medial meniscectomy, and length of follow-up were associated with radiographic knee OA after ACL surgery. Stepwise multivariable logistic regression indicated that prior medial meniscectomy (95% confidence interval [CI], 1.39-6.85), grade 2 or greater medial chondrosis (95% CI, 1.27-6.73), length of follow-up (95% CI, 1.07-1.24), and BMI (overweight 95% CI, 1.08-3.84; obese 95% CI, 1.34-7.80) were the best set of predictors of knee OA.

CONCLUSION

Despite reduced laxity and instability and improved activity and participation, individuals who have undergone ACL reconstruction are still at high risk for developing knee OA compared with the general population. The strongest predictors of knee OA after ACL reconstruction were obesity and grade 2 or greater chondrosis in the medial compartment. These results may aid in identifying patients at risk for OA after ACL reconstruction.

Tibial rotation in single- and double-bundle ACL reconstruction: a kinematic 3-D in vivo analysis

PURPOSE

The effect of double-bundle ACL reconstruction on knee kinematics has recently been studied by several authors under controlled laboratory conditions however little evidence has been derived from dynamic in vivo evaluations. This study hypothesized that tibial rotation during pivoting motor tasks would be better restored after double-bundle ACL reconstructions when compared with single-bundle procedures.

METHODS

Twenty patients with a chronic ACL rupture were randomly assigned to receive a single- or double-bundle ACL reconstruction. Both knees were evaluated pre-operatively by kinematic 3-D gait analysis while performing low- and high-demand motor tasks, including pivoting. At 6 months post-operatively, measurements were repeated in 16 patients. Ten healthy, sex- and age-matched subjects with no history of lower limb pathology formed the control group. The tibial rotational excursion was set as the dependent variable.

RESULTS

The results indicate that at 6 months after surgery both "anatomic" single- and double-bundle ACL reconstruction are able to restore tibial rotational excursion when compared with the contralateral knees and with control knees from uninjured subjects. Chronic ACL-deficient patients show an increase in tibial rotation in both knees during high-demand pivoting tasks.

CONCLUSIONS

Both "anatomic" single- and double-bundle ACL reconstruction adequately restore tibial rotational excursion in a human, "in vivo" kinematic model. As knee stability measurements by in vivo kinematic 3-D analysis more accurately represent actual knee loading during activities, the results of this study might better correlate with functional outcome after ACL reconstructions compared with static knee stability tests or ex vivo laboratory experiments. In such, the results of this dynamic study do not support the theoretical advantage of a double-bundle ACL reconstruction over an "anatomic" single-bundle ACL reconstruction.

A matched pairs comparison of single- versus double-bundle anterior cruciate ligament reconstructions, clinical results and manual laxity testing

PURPOSE

To compare the subjective clinical results as well as manual anterior and rotational stability in patients treated with either single- (SB) or double-bundle (DB) anterior cruciate ligament (ACL) reconstructions.

METHODS

Sixty-four patients who had undergone SB or DB hamstring ACL reconstruction with hamstrings were included in a retrospective matched pair analysis. At follow-up IKDC subjective, CKS, KOOS, CKS and a visual analogue satisfaction scale was assessed. A blinded surgeon examined the joint laxity and completed the objective IKDC. The KT-1000 was used to bilaterally test anterior tibial translation. Patients with confounding variables, which statistically influenced the clinical outcome (passive flexion and extension deficits, persistent quadriceps deficit, tibiofemoral osteoarthritis and non-repairable medial meniscus injury), were identified and excluded from the statistical analysis (n = 10).

RESULTS

For all subjective scores, DB patients reported increased scores compared with SB patients. While consistently higher scores were demonstrated, statistical significance was only achieved for the IKDC subjective (P = 0.04) and VAS satisfaction (P = 0.02). Graded stability results of the Lachman, anterior drawer and pivot-shift tests were significantly higher in the DB group and KT-1000 side-to-side difference was significantly better for DB (P = 0.01).

CONCLUSION

DB ACL reconstruction appeared to more consistently result in significantly higher subjective outcome scores and manual tests of joint stability than SB ACL reconstruction. Besides the surgical technique, normal extension and quadriceps strength after surgery were identified to be an essential component in order to provide the patient with a successful outcome.

Magnetic resonance imaging evaluation of knee kinematics after anterior cruciate ligament reconstruction with anteromedial and transtibial femoral tunnel drilling techniques

PURPOSE

The purpose of this study was to use magnetic resonance (MR) imaging to evaluate the translational and rotational kinematics of anterior cruciate ligament (ACL) reconstructed knees with transtibial (TT) and anteromedial (AM) femoral tunnel drilling.

METHODS

ACL reconstruction was performed in 21 subjects: 12 with AM drilling (5 men and 7 women; mean age, 33 ± 9 years; imaged 18 ± 5 months after surgery) and 9 with TT drilling (5 men and 4 women; mean age, 32 ± 9 years; imaged 12 ± 8 months after surgery). Three-tesla MR imaging was obtained bilaterally at extension and 30° to 40° of flexion under simulated loading (125 N). MR images were segmented and kinematic calculations done with in-house MATLAB software (The MathWorks, Natick, MA). Translation and rotation of the tibia and the tibiofemoral contact area were measured. Statistical analysis treated reconstructed and contralateral knees as independent groups. Reconstructed groups were compared with analysis of covariance using contralateral knees as baseline. P < .05 indicated significance.

RESULTS

All kinematic measures in the AM group were similar to contralateral knees. The TT group showed significantly more total tibial rotation than contralateral knees (TT, 8.4° ± 3.9°; contralateral, 2.9° ± 6.8°) (P = .03), whereas the AM group did not (AM, 3.1° ± 5.6°; contralateral, 2.3° ± 5.4°) (P = .36). At knee extension, the tibia was more externally rotated in the TT group than in controls. Medial tibial translation was greater in the TT group than in controls. The AM group showed increased contact area in the lateral compartment compared with controls; no differences were seen in the TT group.

CONCLUSIONS

Using an MR-based approach, we found that knee kinematics were better restored with the AM femoral tunnel drilling ACL reconstruction than with the TT femoral tunnel drilling approach, which resulted in increased knee laxity. Our in vivo results support previous cadaveric and clinical studies that have found AM ACL reconstruction to restore anatomy and stability better than the TT approach. However, the clinical significance of increased contact area in the AM group remains unclear.

LEVEL OF EVIDENCE

Level III, retrospective comparative study.

The concept of complete footprint restoration with guidelines for single- and double-bundle ACL reconstruction

PURPOSE

This article introduces guidelines for single- (SB) and double-bundle (DB) ACL reconstruction based on the concept of complete footprint restoration. The goal is to reconstruct a maximum of anterior cruciate ligament (ACL) insertion site area to regain a maximum of ACL function. The concept is based on the hypothesis that the restored biomechanical envelope of the knee is a function of reconstructed ACL insertion site area.

METHODS

Individual combinations of graft diameters and drill angles were calculated and matched for all individual insertion site lengths between 8 and 21 mm to maximize the percentage of anatomical footprint restoration. An "insertion site table" was developed to propose individual guidelines during ACL surgery for SB and DB ACL reconstruction based on the intraoperative measurement of the tibial insertion site length.

RESULTS

Our calculations support the use of SB in "small footprints" up to 13 mm, which may restore more than 95% of the native insertion site length. "Intermediate footprints" between 14 and 15 mm may be restored by both a SB or DB ACL reconstruction. For "larger footprints" of 16 mm or more, DB has the potential to replicate 97% or more of the insertion site length which cannot be achieved by a SB ACL reconstruction.

CONCLUSIONS

The concept of complete footprint restoration aims to reconstruct a maximum of ACL insertion site area to restore a maximum of functional envelope of the knee. Depending on the individual situation, different surgical approaches (SB/DB), graft diameters and drill angles may apply. An "insertion site table" was designed to give guidelines for SB and DB reconstruction during surgery. According to the new concept, DB ACL reconstruction is only considered as a surgical tool for large footprints and is not indicated for smaller ones.

Single-bundle patellar tendon versus non-anatomical double-bundle hamstrings ACL reconstruction: a prospective randomized study at 8-year minimum follow-up

PURPOSE

The purpose of this study was to compare subjective, objective and radiographic outcome of the lateralized single-bundle bone-patellar tendon-bone autograft with a non-anatomical double-bundle hamstring tendons autograft anterior cruciate ligament (ACL) reconstruction technique at long-term follow-up.

METHODS

Seventy-nine non-consecutive randomized patients (42 men; 37 women) with unilateral ACL insufficiency were prospectively evaluated, before and after ACL reconstruction by means of the above-mentioned techniques, with a minimum follow-up of 8 years (range 8-10 years; mean 8.6 years). In the double-bundle hamstrings technique, we used one tibial and one femoral tunnel combined with one "over-the-top" passage, cortical staple's fixation and we left intact hamstrings' tibial insertion. Patients were evaluated subjectively and objectively, using IKDC score, Tegner level, manual maximum displacement test with KT-2000™ arthrometer. Radiographic evaluation was performed according to IKDC grading system, and re-intervention rate for meniscal lesions was also recorded.

RESULTS

The subjective and objective IKDC were similar in both groups while double-bundle hamstrings group showed significantly higher Tegner level (P = 0.0007), higher passive range of motion recovery (P = 0.0014), faster sport resumption (P = 0.0052), lower glide pivot-shift phenomenon (P = 0.0302) and lower re-intervention rate (P = 0.0116) compared with patellar tendon group. Radiographic evaluation showed significant lower objective degenerative changes in double-bundle hamstrings group at final follow-up (P = 0.0056).

CONCLUSION

Although both techniques provide satisfactory results, double-bundle ACL reconstruction shows better functional results, with a faster return to sport activity, a lower re-operation rate and lower degenerative knee changes.

Knee function and prevalence of knee osteoarthritis after anterior cruciate ligament reconstruction: a prospective study with 10 to 15 years of follow-up

BACKGROUND

Few prospective long-term studies of more than 10 years have reported changes in knee function and radiologic outcomes after anterior cruciate ligament (ACL) reconstruction.

PURPOSE

To examine changes in knee function from 6 months to 10 to 15 years after ACL reconstruction and to compare knee function outcomes over time for subjects with isolated ACL injury with those with combined ACL and meniscal injury and/or chondral lesion. Furthermore, the aim was to compare the prevalence of radiographic and symptomatic radiographic knee osteoarthritis between subjects with isolated ACL injuries and those with combined ACL and meniscal and/or chondral lesions 10 to 15 years after ACL reconstruction.

STUDY DESIGN

Cohort study; Level of evidence, 2.

METHODS

Follow-up evaluations were performed on 221 subjects at 6 months, 1 year, 2 years, and 10 to 15 years after ACL reconstruction with bone-patellar tendon-bone autograft. Outcome measurements were KT-1000 arthrometer, Lachman and pivot shift tests, Cincinnati knee score, isokinetic muscle strength tests, hop tests, visual analog scale for pain, Tegner activity scale, and the Kellgren and Lawrence classification.

RESULTS

One hundred eighty-one subjects (82%) were evaluated at the 10- to 15-year follow-up. A significant improvement over time was revealed for all prospective outcomes of knee function. No significant differences in knee function over time were detected between the isolated and combined injury groups. Subjects with combined injury had significantly higher prevalence of radiographic knee osteoarthritis compared with those with isolated injury (80% and 62%, P = .008), but no significant group differences were shown for symptomatic radiographic knee osteoarthritis (46% and 32%, P = .053).

CONCLUSION

An overall improvement in knee function outcomes was detected from 6 months to 10 to 15 years after ACL reconstruction for both those with isolated and combined ACL injury, but significantly higher prevalence of radiographic knee osteoarthritis was found for those with combined injuries.

Anterior cruciate ligament graft reconstruction: clinical, technical, and imaging overview

The anterior cruciate ligament (ACL) is one of the most frequently torn ligaments of the knee. With more than 100,000 ACL reconstructions performed yearly in the United States, evaluation of ACL grafts with magnetic resonance imaging is a common occurrence in daily clinical practice. Anterior cruciate ligament reconstructions vary from single bundle, double bundle, selective bundle, and physeal-sparing techniques. Complications of ACL graft reconstructions include graft tears, graft laxity, arthrofibrosis, and hardware failure or migration. This article offers a comprehensive review of ACL reconstruction for the consulting radiologist.