Younger patients are at increased risk for graft rupture and contralateral injury after anterior cruciate ligament reconstruction

Validation of a Risk Calculator to Personalize Graft Choice and Reduce Rupture Rates for Anterior Cruciate Ligament Reconstruction

BACKGROUND

Anterior cruciate ligament reconstructions (ACLRs) fail at an alarmingly high rate in young active individuals. The Multicenter Orthopaedic Outcomes Network (MOON) knee group has developed an autograft risk calculator that uses patient characteristics and lifestyle to predict the probability of graft rupture if the surgeon uses a hamstring tendon (HT) or a bone-patellar tendon-bone (BPTB) graft to reconstruct the ligament. If validated, this risk calculator can be used during the shared decision-making process to make optimal ACLR autograft choices and reduce rupture rates. The STABILITY 1 randomized clinical trial offers a large, rigorously collected data set of similar young active patients who received HT autograft with or without lateral extra-articular tenodesis (LET) for ACLR.

PURPOSE/HYPOTHESIS

The purpose was to validate the ACLR graft rupture risk calculator in a large external data set and to investigate the utility of BPTB and LET for ACLR. We hypothesized that the risk calculator would maintain adequate discriminative ability and calibration in the external STABILITY 1 data set when compared with the initial MOON development data set.

STUDY DESIGN

Cohort study (diagnosis); Level of evidence, 1.

METHODS

The model predictors for the risk calculator include age, sex, body mass index, sport played at the time of injury, Marx Activity Score, preoperative knee laxity, and graft type. The STABILITY 1 trial data set was used for external validation. Discriminative ability, calibration, and diagnostic test validity of the model were assessed. Finally, predictor strength in the initial and validation samples was compared.

RESULTS

The model showed acceptable discriminative ability (area under the curve = 0.73), calibration (Brier score = 0.07), and specificity (85.3%) to detect patients who will experience a graft rupture. Age, high-grade preoperative knee laxity, and graft type were significant predictors of graft rupture in young active patients. BPTB and the addition of LET to HT were protective against graft rupture versus HT autograft alone.

CONCLUSION

The MOON risk calculator is a valid predictor of ACLR graft rupture and is appropriate for clinical practice. This study provides evidence supporting the idea that isolated HT autografts should be avoided for young active patients undergoing ACLR.

REGISTRATION

NCT00463099 (MOON); NCT02018354 (STABILITY 1) (ClinicalTrials.gov identifiers).

Mechanics of cadaveric anterior cruciate ligament reconstructions during simulated jump landing tasks: Lessons learned from a pilot investigation

BACKGROUND

Around half of anterior cruciate ligament (ACL) injuries are treated through reconstruction, but the literature lacks mechanical investigation of reconstructions in a dynamic athletic task and rupture environment. The current objective was to ascertain the feasibility of investigating ACL reconstructions in a rupture environment during simulated landing tasks in a validated mechanical impact simulator.

METHODS

Four cadaveric lower extremities were subjected to simulated landing in a mechanical impact simulator. External joint loads that mimicked magnitudes recorded from an in vivo population were applied to each joint in a stepwise manner. Simulations were repeated until ACL failure was achieved. Repeated measures design was used to test each specimen in the native ACL and hamstrings, quadriceps, and patellar tendon reconstructed states.

FINDINGS

ACL injuries were generated in 100% of specimens. Graft substance damage occurred in 58% of ACLRs, and in 75% of bone tendon bone grafts. Bone tendon bone and quadriceps grafts survived greater simulated loading than hamstrings grafts, but smaller simulated loading than the native ACL. Median peak strain prior to failure was 20.3% (11.6, 24.5) for the native ACL and 17.4% (9.5, 23.3) across all graft types.

INTERPRETATION

The simulator was a viable construct for mechanical examination of ACLR grafts in rupture environments. Post-surgery, ACL reconstruction complexes are weaker than the native ACL when subjected to equivalent loading. Bone tendon bone grafts most closely resembled the native ligament and provided the most consistently relevant rupture results. This model advocated reconstruction graft capacity to sustain forces generated from immediate gait and weightbearing during rehabilitation from an ACL injury.

Anterior Cruciate Ligament Reconstruction and Lateral Plasty in High-Risk Young Adolescents: Revisions, Subjective Evaluation, and the Role of Surgical Timing on Meniscal Preservation

BACKGROUND

In adolescents, the rate of meniscal injury at the time of anterior cruciate ligament (ACL) reconstruction, the rate of ACL graft revision, and clinical outcomes has not yet been investigated.

HYPOTHESIS

In patients younger than 16 years, the rate of meniscal injuries at the time of ACL reconstruction increases with time from injury. The mid-term revision rate and reoperation rate after ACL reconstruction with hamstrings and lateral tenodesis are lower than those reported in literature for isolate ACL reconstruction.

STUDY DESIGN

Case series.

LEVEL OF EVIDENCE

Level 4.

METHODS

Patients younger than 16 years who underwent ACL reconstruction with hamstring and lateral tenodesis, with a follow-up ≥2 years were included. The number of meniscal lesions was stratified according to the delay between injury-to-surgery (<3, 3-12, >12 months). All reoperations, Lysholm score, Knee Injury and Osteoarthritis Outcome Score subscales for pain (at rest and during activity), and return to sport were collected.

RESULTS

A total of 151 patients (mean age 14.8 ± 1.2 years) were included. Patients undergoing surgery at <3 months after injury had a lower meniscal injury rate (36%) than those treated at 3 to 12 months (55%) and >12 months (63%) after injury (P = 0.04). Medial meniscal lesions were more likely to be repaired when surgery was performed <3 months after injury (91%). Subjective follow-up data were available for 132 patients, and 19 were lost to follow-up. At 6.0 ± 2.6 years, 6% of patients underwent ACL revision; 1 of 20 (5%) patients with posterior tibial slope ≥12° and 4 of 45 (9%) patients with Tegner level ≥8. Nine new meniscal procedures were performed; 19% of repaired menisci underwent meniscectomy. Good or excellent Lysholm score was reported by 88% of patients; 56% of patients with concurrent lateral meniscectomy had pain during activity, 91% returned to sport, and 79% were still participating at final follow-up.

CONCLUSION

Patients younger than 16 years undergoing ACL reconstruction within 3 months from injury had the lowest rate of meniscal injuries. ACL reconstruction with lateral tenodesis had low revision rate (6%) and good or excellent clinical outcomes in 88% of young adolescents.

CLINICAL RELEVANCE

Sport physicians should be aware that adolescent patients undergoing ACL reconstruction within 3 months after injury have the lowest rate of meniscal injuries; the mid-term revision rate of ACL reconstruction with lateral plasty is lower than 10% and the patients' perceived outcomes are good with almost all patients returning to sport activity.

Clinical Risk Profile for a Second Anterior Cruciate Ligament Injury in Female Soccer Players After Anterior Cruciate Ligament Reconstruction

BACKGROUND

The risk of a second anterior cruciate ligament (ACL) injury when participating in pivoting sports after ACL reconstruction is high. Risk factors associated with a second ACL injury are complex.

PURPOSE

To investigate the combinations of various clinical risk factors associated with second ACL injury in female soccer players with a primary unilateral ACL reconstruction, using Classification and Regression Tree (CART) analysis.

STUDY DESIGN

Cohort study; Level of evidence, 2.

METHODS

A total of 117 active female soccer players (mean ± SD age, 20 ± 2 years) were included. Athletes were enrolled 19 ± 9 months after ACL reconstruction and were prospectively followed for 2 years. At baseline, all players underwent assessment of knee and ankle joint range of motion (ROM), participated in functional tests (postural control, hop performance, and movement asymmetries in the lower limbs and trunk), and answered questionnaires (patient-reported knee function, knee-related quality of life, psychological and personality factors). A clinical prediction model using CART was developed.

RESULTS

A total of 28 players (24%) sustained a second ACL injury (21 ipsilateral and 7 contralateral ruptures) while playing soccer. CART analysis selected 9 of 19 independent variables associated with second ACL injury: the 5-jump test, knee collapse on the non-ACL reconstructed leg in a drop vertical jump, tuck jump, limb symmetry index on side hop and the single hop for distance, side difference in ankle dorsiflexion ROM, and scores for the questionnaires ACL-Return to Sport After Injury and the Swedish Universities Scales of Personality subscales of Stress Susceptibility and Adventure Seeking. The accuracy of the model was 89%, with 100% sensitivity and 76% specificity. CART analysis indicated that the interaction of longer jumps in the 5-jump test (>916 cm) with more side difference in ankle dorsiflexion ROM (>-2.5°) and more knee valgus collapse in the nonreconstructed knee (>-1.4 cm) (relative risk, 4.03; 95% CI, 2.21-7.36) best predicted an increased likelihood of a second ACL injury.

CONCLUSION

The risk profiles selected by CART could accurately identify female soccer players at high risk for a second ACL injury. There was an interaction between functional performance, clinical assessment, and psychological factors, and it is reasonable to include these factors in return-to-sport decisions and in athlete screening after ACL injury.

Effect of Anterior Cruciate Ligament Rupture on Physical Activity, Sports Participation, Patient-Reported Health Outcomes, and Physical Function in Young Female Athletes

BACKGROUND

Return to sports (RTS) is frequently considered an indicator of successful recovery after anterior cruciate ligament reconstruction (ACLR). However, despite the well-recognized health benefits of physical activity (PA), little is known about objectively measured PA in the 1 to 2 years after ACLR. Given that young female athletes have a high prevalence of ACLR and lower RTS rates as compared with their male counterparts, an in-depth examination of PA in this subgroup is warranted.

HYPOTHESIS

We hypothesized that female youth and young adults who have had ACLR in the previous 1 to 2 years would have less moderate or vigorous PA (MVPA) compared with healthy matched controls. We also hypothesized that the ACLR group would report lower levels of sports participation, patient-reported health outcomes, and physical function.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

Participants included 51 female athletes with primary unilateral ACLR for a sports-related injury in the previous 1 to 2 years and 51 age- and sports-matched controls. Outcomes included objectively measured PA (GT3X accelerometers), previous and current sports participation and RTS, body mass index, Knee injury and Osteoarthritis Outcome Score (KOOS), triple single-leg hop, and one-leg rise. Mean within-pair differences with 95% CIs were used to assess differences between groups across all outcomes. Multivariable linear regression (clustered by pair) was used to examine whether the ACLR group had less MVPA than did the age- and sports-matched control group, adjusting for total wear time, age, time since injury, and body mass index.

RESULTS

Median age was 17.8 years (range, 14.6-22.6 years). There was no significant difference between groups in MVPA. However, the injury group had fewer mean minutes per day of vigorous PA (-1.22; 95% CI, -2.40 to -0.04), poorer KOOS values on all subscales, and shorter triple single-leg hop distance. In the injury group, 28 (55%) returned to sports, including 14 (27.5%) who returned at preinjury performance level. Across both groups, over one-third changed their most important sport, shifting toward an individual-based sport.

CONCLUSION

At 1 to 2 years after ACLR, female athletes demonstrated no differences in combined MVPA and only a very small reduction in vigorous PA, yet they had higher levels of self-reported knee pain and symptoms, reduced knee function in sports, lower quality of life, and poorer objective knee function compared with matched controls.

Test Batteries After Primary Anterior Cruciate Ligament Reconstruction: A Systematic Review

CONTEXT

There is a lack of consensus regarding test batteries for return to sport (RTS) after anterior cruciate ligament reconstruction (ACLR).

OBJECTIVE

To report the RTS test batteries for individuals after ACLR and to examine alignment with the American Academy of Orthopaedic Surgeons (AAOS) Appropriate Use Criteria (AUC). Finally, to examine how published RTS batteries prior to the AAOS AUC (2010-2015) compared with those after publication of the AUC (2016-2020).

DATA SOURCE

A systematic search of PubMed (2010-2020).

STUDY SELECTION

Studies were included if they were published from 2010 to 2020, patients underwent primary ACLR and were tested between 6 months and 2 years postoperatively and included a minimum of 2 assessments. Studies were excluded if patients were tested outside the designated time; had undergone a revision, contralateral, or multiligament injury; included healthy participants; were level 5 evidence or the study was a systematic review. A total of 1012 articles were reviewed and 63 met the criteria.

STUDY DESIGN

Systematic review.

LEVEL OF EVIDENCE

Level 4.

DATA EXTRACTION

Information regarding the RTS batteries and patient demographics were extracted from the included articles.

RESULTS

A total of 63 studies met the inclusion and exclusion criteria (22 from 2010-2015 and 41 from 2016-2020). The most common RTS batteries included the hop test, quadriceps strength test, and patient-reported outcome measures. No study met all 7 AUC; the most common criteria met were functional skills (98.4%), followed by confidence (22.2%), then range of motion and knee stability (20.6%).

CONCLUSION

The test batteries in the current literature show high variability and a lack of essential components necessary for RTS. No study met the AUC guidelines, suggesting a disconnect between recommended guidelines and clinical practice. Test battery research has expanded over the past decade; however, standardized, clinically applicable batteries that encompass all criteria are needed.

Preservation of the Tibial Stump During Anterior Cruciate Ligament Reconstruction Surgery Did Not Increase the Rate of Surgery for Symptomatic Cyclops Lesions

Background

Preservation of the tibial stump during anterior cruciate ligament reconstruction (ACLR) is controversial. While proposed benefits include enhanced graft revascularization, improved proprioception, and decreased graft rupture rates, a potential complication is the development of a symptomatic cyclops lesion. It is therefore important to determine whether any benefits outweigh potential complications.

Purpose

To determine whether greater preservation of the tibial stump remnant would be associated with a decreased graft rupture rate without a concomitant increase in the rate of surgery for symptomatic cyclops lesions at 2 years after ACLR.

Study Design

Cohort study; Level of evidence, 3.

Methods

A cohort of 658 patients in whom the amount of tibial stump preserved was classified as no stump (n = 228), <50% (n = 342), or >50% (n = 88) was followed up for 2 years, with graft ruptures and surgical treatment for cyclops lesions recorded. Contingency and Kaplan-Meier survival analyses were used to determine trends among the 3 remnant preservation groups in terms of graft rupture rates and surgery for cyclops lesions. Subgroup analysis was also conducted to examine sex-based differences.

Results

There was no significant association between graft rupture rates and remnant preservation. There was a significant trend for fewer operations for symptomatic cyclops lesions with greater remnant preservation when the entire cohort was analyzed (P = .04) and also when only female patients were analyzed (P = .04).

Conclusion

Although preservation of the tibial stump remnant was not associated with a reduced graft rupture rate, it was also not associated with increased rates of surgery for symptomatic cyclops lesions.

Magnetic Resonance Imaging 1 Year After Hamstring Autograft Anterior Cruciate Ligament Reconstruction Can Identify Those at Higher Risk of Graft Failure: An Analysis of 250 Cases

BACKGROUND

There is currently no analysis of 1-year postoperative magnetic resonance imaging (MRI) that reproducibly evaluates the graft of a hamstring autograft anterior cruciate ligament reconstruction (ACLR) and helps to identify who is at a higher risk of graft rupture upon return to pivoting sports.

PURPOSE

To ascertain whether a novel MRI analysis of ACLR at 1 year postoperatively can be used to predict graft rupture, sporting level, and clinical outcome at a 1-year and minimum 2-year follow-up.

STUDY DESIGN

Case-control study; Level of evidence, 3.

METHODS

Graft healing and integration after hamstring autograft ACLR were evaluated using the MRI signal intensity ratio at multiple areas using oblique reconstructions both parallel and perpendicular to the graft and tunnel apertures. Clinical outcomes were assessment of side-to-side laxity and International Knee Documentation Committee (IKDC) Subjective Knee Evaluation Form, Lysholm, and Tegner activity level scores at 1 year. Repeat outcome measures and detection of graft rupture were evaluated at a minimum of 2 years.

RESULTS

A total of 250 patients (42.4% female) underwent MRI analysis at 1 year, and assessment of 211 patients between 1 year and the final follow-up (range, 24-36 months) detected 9 graft ruptures (4.3%; 5 in female patients). A significant predictor for graft rupture was a high signal parallel to the proximal intra-articular graft and perpendicular to the femoral tunnel aperture (P = .032 and P = .049, respectively), with each proximal graft signal intensity ratio (SIR) increase by 1 corresponding to a 40% increased risk of graft rupture. A cutoff SIR of 4 had a sensitivity and specificity of 66% and 77%, respectively, in the proximal graft and 88% and 60% in the femoral aperture. In all patients, graft signal adjacent to and within the tibial tunnel aperture, and in the mid intra-articular portion, was significantly lower than that for the femoral aperture (P < .001). A significant correlation was seen between the appearance of higher graft signal on MRI and those patients achieving top sporting levels by 1 year.

CONCLUSION

ACLR graft rupture after 1 year is associated with MRI appearances of high graft signal adjacent to and within the femoral tunnel aperture. Patients with aspirations of quickly returning to a high sporting level may benefit from MRI analysis of graft signal. Graft signal was highest at the femoral tunnel aperture, adding further radiographic evidence that the rate-limiting step to graft healing occurs proximally.

The Role of Psychological Readiness in Return to Sport Assessment After Anterior Cruciate Ligament Reconstruction

BACKGROUND

Knowledge about the predictive value of return to sport (RTS) test batteries applied after anterior cruciate ligament reconstruction (ACLR) is limited. Adding assessment of psychological readiness has been recommended, but knowledge of how this affects the predictive ability of test batteries is lacking.

PURPOSE

To examine the predictive ability of a RTS test battery on return to preinjury level of sport and reinjury when evaluation of psychological readiness was incorporated.

STUDY DESIGN

Cohort study; Level of evidence, 2.

METHODS

A total of 129 patients were recruited 9 months after ACLR. Inclusion criteria were age ≥16 years and engagement in sports before injury. Patients with concomitant ligamentous surgery or ACL revision surgery were excluded. Baseline testing included single-leg hop tests, isokinetic strength tests, the International Knee Documentation Committee (IKDC) Subjective Knee Form 2000, a custom-made RTS questionnaire, and the Anterior Cruciate Ligament-Return to Sport after Injury (ACL-RSI) scale. The RTS criteria were IKDC 2000 score ≥85% and ≥85% leg symmetry index on hop and strength test. At a 2-year follow-up evaluation, further knee surgery and reinjuries were registered and the RTS questionnaire was completed again. Regression analyses and receiver operating characteristic analyses were performed to study the predictive ability of the test battery.

RESULTS

Out of the 103 patients who completed the 2-year follow-up, 42% returned to their preinjury level of sport. ACL-RSI 9 months after surgery (odds ratio [OR], 1.03) and age (OR, 1.05) predicted RTS. An ACL-RSI score <47 indicated that a patient was at risk of not returning to sport (area under the curve 0.69; 95% CI, 0.58-0.79), with 85% sensitivity and 45% specificity. The functional tests did not predict RTS. Six patients sustained ACL reinjuries and 7 underwent surgery for other knee complaints/injuries after RTS testing. None of the 29 patients who passed all RTS criteria, and were therefore cleared for RTS, sustained a second knee injury.

CONCLUSION

ACL-RSI and age were predictors of 2-year RTS, while functional tests were not informative. Another main finding was that none of the patients who passed the 85% RTS criteria sustained another knee injury.

Self-Tensioning Feature of Knotless Suture Anchor Provides Reproducible Knotless Fixation Independent of Initial Tension

Background:

Anterior cruciate ligament (ACL) reconstruction with suture tape reinforcement has been shown to biomechanically reduce elongation and increase ultimate strength. However, the amount and consistency of the achieved tension after primary fixation using knotless suture anchors remains unclear.

Purpose:

To determine whether initial tensioning of suture tape before fixation with a knotless suture anchor significantly affects final tension of the suture tape.

Study Design:

Controlled laboratory study.

Methods:

We secured 15 pairs of Sawbones blocks with predrilled tunnels to a tensile testing machine. Suture tape was inserted through a suspensory fixation button on the representative femoral block and threaded top-down through the base of the tibial block over an attachable button system. The suture tape was attached with a knotless suture anchor in a predrilled and tapped hole on the tibial block under the following pretensioning conditions: (1) slight tension of 5 N, (2) no tension, and (3) initial slack. The suture anchor was inserted as the load-time data were recorded. After initial block testing, a porcine model of 24 tibias was used to test the same pretensioning conditions. The initial loads during anchor insertion and screw-in were measured, as well as final tension.

Results:

During block testing, no difference in final tensioning was found when comparing the slight-tension, no-tension, and slack groups (42.3 ± 5.3, 37.7 ± 6.4, and 40.2 ± 7.0 N, respectively; P = .528). Similar to block testing, no difference in final tensioning was found when comparing the slight-tension, no-tension, and slack groups using the porcine model (43.64 ± 6.69, 48.09 ± 13.93, and 44.52 ± 6.84 N, respectively; P = .633).

Conclusion:

The final tension of the suture tape construct appears to be reproducible and consistent, independent of the initial tension introduced with suture anchor placement within the tested parameters.

Clinical Relevance:

The results of the current study can help optimize the placement technique of independent suture tape reinforcement for ACL reconstruction, which is a promising strategy to help prevent ACL rerupture, particularly in the early phases of postoperative rehabilitation.

Risk Factors for Failure After Anterior Cruciate Ligament Reconstruction in a Pediatric Population: A Prediction Algorithm

Background:

Anterior cruciate ligament reconstruction (ACLR) in pediatric patients is becoming increasingly common. There is growing yet limited literature on the risk factors for revision in this demographic.

Purpose:

To (1) determine the rate of pediatric revision ACLR in a nationally representative sample, (2) ascertain the associated patient- and injury-specific risk factors for revision ACLR, and (3) examine the differences in the rate and risks of revision ACLR between pediatric and adult patients.

Study Design:

Case-control study; Level of evidence, 3.

Methods:

The PearlDiver patient record database was used to identify adult patients (age ≥20 years) and pediatric patients (age <20 years) who underwent primary ACLR between 2010 and 2015. At 5 years postoperatively, the risk of revision ACLR was compared between the adult and pediatric groups. ACLR to the contralateral side was also compared. Multivariate logistic regression was used to determine the significant risk factors for revision ACLR and the overall reoperation rates in pediatric and adult patients; from these risk factors, an algorithm was developed to predict the risk of revision ACLR in pediatric patients.

Results:

Included were 2055 pediatric patients, 1778 adult patients aged 20 to 29 years, and 1646 adult patients aged 30 to 39 years who underwent ACLR. At 5 years postoperatively, pediatric patients faced a higher risk of revision surgery when compared with adults (18.0 % vs 9.2% [adults 20-29 years] and 7.1% [adults 30-39 years]; P < .0001), with significantly decreased survivorship of the index ACLR (P < .0001; log-rank test). Pediatric patients were also at higher risk of undergoing contralateral ACLR as compared with adults (5.8% vs 1.6% [adults 20-29 years] and 1.9% [adults 30-39 years]; P < .0001). Among the pediatric cohort, boys (odds ratio [OR], 0.78; 95% CI, 0.63-0.96; P = .0204) and patients >14 years old (OR, 0.62; 95% CI, 0.45-0.86; P = .0035) had a decreased risk of overall reoperation; patients undergoing concurrent meniscal repair (OR, 1.84; 95% CI, 1.43-2.38; P < .0001) or meniscectomy (OR, 2.20; 95% CI, 1.72-2.82; P < .0001) had an increased risk of revision surgery. According to the risk algorithm, the highest probability for revision ACLR was in girls <15 years old with concomitant meniscal and medial collateral ligament injury (36% risk of revision).

Conclusion:

As compared with adults, pediatric patients had an increased likelihood of revision ACLR, contralateral ACLR, and meniscal reoperation within 5 years of an index ACLR. Families of pediatric patients—especially female patients, younger patients, and those with concomitant medial collateral ligament and meniscal injuries—should be counseled on such risks.

Effectiveness of thicker hamstring or patella tendon grafts to reduce graft failure rate in anterior cruciate ligament reconstruction in young patients

PURPOSE

The purpose of this study was to determine the anterior cruciate ligament reconstruction (ACLR) failure rate in young patients utilizing the New Zealand (NZ) anterior cruciate ligament (ACL) Registry. The hypothesis was that the ACLR rupture rate would be lower for thicker hamstring graft and bone patellar tendon bone (BPB) grafts in comparison to the classic hamstring technique. The ACLR failure rate was assessed according to graft type and patients' sex.

METHODS

The NZ ACL registry was utilized to identify all patients aged 20 years or younger at the time of surgery who were skeletally mature and had a minimum 2-year follow-up. Graft ruptures, defined as an ACL revision, were identified according to graft type (traditional 4 strands hamstring semitendinosus and gracilis, 4 strands semitendinosus, 5-6 strands semitendinosus and gracilis, 7-8 strands semitendinosus and gracilis, bone-patella-bone graft).

RESULTS

Nine-hundred and ninety-two patients were included. At a mean follow-up of 38 months, 52 cases of graft rupture were recorded, (overall failure rate: 5.2%). The failure rate was not statistically influenced by the graft diameter. Patients with a thinner graft (< 8 mm-196 patients) had a similar failure rate (6%) to patients with a thicker graft (8 mm or more-485 patients) (6.2%). There was a lower failure rate in the BPB group (3.1%) versus all hamstrings group (6%) (ns). Finally, BPB in females had a lower failure rate than all hamstring constructs together (0% versus 5.1%; p = 0.023) CONCLUSION: In a young population traditional four-strand hamstring grafts, multiple strand configurations or BPB ACLR, whatever their size (> or < 8 mm), showed no significant difference in the failure rate in the NZ ACL registry. Female patients who had an ACL reconstruction with BPB graft had a significant lower failure rate than patients who had a hamstring graft.

LEVEL OF EVIDENCE

III.

Neuromuscular Training Improves Biomechanical Deficits at the Knee in Anterior Cruciate Ligament-Reconstructed Athletes

OBJECTIVE

Athletes who return to sport after anterior cruciate ligament reconstruction (ACLR) demonstrate persistent biomechanical and neuromuscular deficits of the knee. There is limited evidence on what effect a neuromuscular training (NMT) program has on knee biomechanics in a cohort of athletes with ACLR. Therefore, the primary aim of this study was to quantify the effect of an NMT program on knee biomechanics in a cohort of ACLR athletes. Second, the post-training knee biomechanics were compared between the cohort of ACLR and control athletes.

DESIGN

Cohort study.

SETTING

Controlled laboratory setting.

PARTICIPANTS

Eighteen athletes with ACLR and 10 control athletes.

INTERVENTIONS

Neuromuscular training.

MAIN OUTCOME MEASURES

Knee kinematics and kinetics during a double-limb jump-landing task.

RESULTS

There were no significant interactions (P > 0.05) observed for the athletes with ACLR. However, there was a significant main effect of biomechanics testing session (P < 0.05) for knee flexion angle and moments; athletes with ACLR demonstrated greater knee flexion angle and lower knee flexion moment during the post-training biomechanics testing session. Post-training comparison between the ACLR and control athletes demonstrated no significant interactions (P > 0.05) between the groups. There was a significant main effect of group (P < 0.05) for knee frontal angle, as athletes with ACLR landed with greater knee adduction than the control athletes.

CONCLUSIONS

Significant improvements in knee sagittal plane biomechanical measures were observed after the NMT program by the athletes with ACLR. In addition, post-training comparison of the ACLR and control groups demonstrates comparable knee biomechanics.

Secondary Injuries After Pediatric Anterior Cruciate Ligament Reconstruction: A Systematic Review With Quantitative Analysis

BACKGROUND

In the skeletally mature anterior cruciate ligament (ACL) reconstruction population, patients aged <25 years are at significantly increased risk of graft failure and injury to the contralateral ACL. Skeletal immaturity often affects graft selection and reconstruction technique.

PURPOSE

To examine the incidence of ipsilateral graft failure and contralateral ACL injury in the skeletally immature patient population.

STUDY DESIGN

Systematic review and meta-analysis.

METHODS

Using the PRISMA (Preferred Reporting Items for Systematic Meta-Analyses) guidelines, we reviewed all literature that involved ACL reconstruction performed on skeletally immature patients between May 1976 and May 2019. Patient demographics, surgical technique, and the prevalence of ipsilateral graft failure or subsequent contralateral ACL injury were recorded. Ipsilateral, contralateral, and secondary ACL injuries were then compared between sexes via chi-square tests.

RESULTS

A total of 24 articles (1254 children; 1258 knees) met inclusion criteria for analysis. Ipsilateral graft failures occurred in 105 of 1258 patients (8.3%), and there were no statistically significant sex differences in the prevalence of graft failures (female, 9.7%; male patients, 7.1%; P = .14). The prevalence of contralateral ACL injury was significantly greater in female (29/129; 22.5%) than male (18/206; 8.7%; P = .0004) patients in the 9 studies that reported contralateral injury. Skeletally immature female patients were at significantly increased risk of contralateral ACL injury (odds ratio = 3.0; P = .0006) when compared with their male counterparts.

CONCLUSION

In the literature to date, 1 in 3 female skeletally immature patients experienced an ipsilateral graft failure or contralateral ACL injury. Regardless of sex, the 24% prevalence of secondary injury after pediatric ACL reconstruction is almost identical to previously published secondary injury rates in skeletally mature patients <25 years old. As such, skeletal maturity alone does not seem to be a determinant of secondary injury; however, there is a clear need to improve postoperative rehabilitation, activity progression, and return-to-play testing to allow a safe return to sports that protects the long-term health of the reconstructed and contralateral limbs, especially for female patients.

Second ACL Injury Rates in Younger Athletes Who Were Advised to Delay Return to Sport Until 12 Months After ACL Reconstruction

Background:

Younger patients are at increased risk for anterior cruciate ligament (ACL) graft rupture and contralateral injury after ACL reconstruction (ACLR). Increasing the amount of time between surgery and the resumption of competitive sport may reduce this risk.

Purpose:

To determine the rates of graft rupture and injury to the contralateral native ACL at 3- to 5-year follow-up in younger patients who were advised to delay a return to competitive sport until 12 months after surgery and compare this with a nondelayed cohort.

Study Design:

Cohort study; Level of evidence, 3.

Methods:

The primary study cohort consisted of 142 eligible patients aged <20 years when they underwent their first primary ACLR. All were informed about the risk of further injury and advised not to return to competitive sport before 12 months postoperatively. Return-to-sport status and the number of subsequent ACL injuries (graft rupture or a contralateral injury to the native ACL) were determined at 3- to 5-year follow-up and compared with a historic cohort of 299 patients with ACLR who were not advised to delay their return to sport for a set period. The cohorts were then combined, and injury rates were compared between those who returned to sport before and after 12 months postoperatively.

Results:

The follow-up rate was 91% (129/142). In the delayed cohort, 63% returned to competitive sport after 12 months (mean, 14 months). Few patients (n = 10) returned before 9 months. In the delayed group, 33% had a subsequent ACL injury; this was not significantly different when compared with the nondelayed group (31% rate), in which a majority (58%) returned to competitive sport before 12 months. Subsequent ACL injury rates were also similar when compared between patients who returned before and after 12 months postoperatively (33% vs 32%, respectively).

Conclusion:

At midterm follow-up, the overall rates of subsequent ACL injury were high, even for patients who delayed their return until 12 months after surgery. More research is required to identify strategies to reduce the high reinjury rate in younger athletes.

Ten-Year Survivorship, Patient-Reported Outcome Measures, and Patient Acceptable Symptom State After Over-the-Top Hamstring Anterior Cruciate Ligament Reconstruction With a Lateral Extra-articular Reconstruction: Analysis of 267 Consecutive Cases

BACKGROUND

Long-term patient-reported outcome measures (PROMs) and predictors of success or failure after anterior cruciate ligament (ACL) reconstruction are not fully understood, especially when combined with a lateral extra-articular reconstruction.

PURPOSE

To assess the long-term PROMs, revision rate, and predictors of success or failure after ACL reconstructions using an over-the-top surgical technique with single-bundle hamstring tendon autografts and a lateral extra-articular reconstruction.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

The study cohort consisted of 267 consecutive patients (mean age, 30.7 years) who underwent ACL reconstruction with an over-the-top surgical technique with single-bundle hamstring tendon autografts and a lateral extra-articular augmentation between November 2007 and May 2009. The number of subsequent ACL revisions and reoperations were recorded. Subjective clinical status was assessed with PROMs-specifically, the Knee injury and Osteoarthritis Outcome Score (KOOS), Lysholm, Tegner, and visual analog scale for pain-at a minimum follow-up of 10 years.

RESULTS

Overall, 3% of patients underwent ACL revision, with a 10-year survival rate of 96.3%. High sport activity (hazard ratio, 6.9; P = .285) and concomitant meniscal lesion (hazard ratio, 2.6; P = .0487) were predictors of ACL revision or new meniscectomy. The mean ± SD Lysholm score was 94.1 ± 10.8, while that for the visual analog scale for pain was 0.2 ± 0.9 at rest and 2.1 ± 2.6 during activity. KOOS subscale scores were as follows: 95.7 ± 8.1 for Pain, 92.5 ± 10.5 for Symptoms, 98.4 ± 7.4 for Activities of Daily Living, 90.7 ± 17.2 for Sport, and 91.2 ± 17.1 for Quality of Life; respectively, 88%, 99%, 81%, 89%, and 91% of patients achieved the Patient Acceptable Symptom State. Female sex and chondropathy with Outerbridge grade ≥2 were predictors of worse KOOS subscales. Overall, 82% of patients returned to sport, and 57% were still participating at the 10-year evaluation.

CONCLUSION

ACL reconstruction with an over-the-top surgical technique with single-bundle hamstring autografts and a lateral extra-articular reconstruction provided satisfactory results in terms of function, symptoms, sports, and quality of life in 80% to 90% of patients after 10 years. Long-term survivorship was 96%. Sport participation declined from 82% postoperatively to 57% at long-term follow-up. A concomitant medial meniscal lesion was a predictor of higher risk of ACL failure or new meniscal lesion, while advanced chondropathy and female sex were predictors of higher pain, lower function, and poor quality of life scores.

Can Talented Youth Soccer Players Who Have Undergone Anterior Cruciate Ligament Reconstruction Reach the Elite Level?

BACKGROUND

Anterior cruciate ligament (ACL) ruptures are common in soccer players, and reconstructive surgery is often performed to restore knee stability and enable a return to play.

PURPOSE

To investigate whether an ACL reconstruction for talented youth soccer players affects their potential to become elite players at the senior level.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

All soccer players who participated in the Swedish National Elite Camp for 15-year-old players between 2005 and 2011 (N = 5285 players; 2631 boys and 2654 girls) were matched with the Swedish National Knee Ligament Registry to identify the players who had undergone ACL reconstruction. Information on player participation in Swedish league games and level of play was collected from the Swedish Football Association's administrative data system. The players with an ACL reconstruction who were injured at the ages of 15 to 19 years were compared with the rest of the players who participated in the National Elite Camp to see whether an early ACL reconstruction affected whether they remained active as soccer players and their chance to play at the elite level as seniors.

RESULTS

A total of 524 (9.9%) players had undergone an ACL reconstruction, and 292 (5.5%; 75 male and 217 female) had sustained their injury at age 15 to 19 years. During the follow-up period, 122 (23.3%) players underwent ACL reconstruction: revision (11.5%; n = 60) or contralateral (11.8%; n = 62). Male and female soccer players undergoing an ACL reconstruction at age 15 to 19 years experienced no significant effect on being active or playing at the elite level in the season that they turned 21 years old. Of the youth players who underwent ACL reconstruction, 12% of the male players and 11.5% of the female players progressed to the elite level at the age of 21 years compared with 10.3% of the men and 11.1% of the women among the uninjured players.

CONCLUSION

ACL reconstructive surgery in talented youth soccer players offers them the opportunity to become elite players as seniors and permits an activity level on a par with that of their uninjured peers. However, almost 1 in 4 requires further ACL surgery, so the players' future knee health should be considered when deciding on a return to play.

The Impact of Resident Involvement on Surgical Outcomes following Anterior Cruciate Ligament Reconstruction

Hands-on participation in the operating room (OR) is an integral component of surgical resident training. However, the implications of resident involvement in many orthopaedic procedures are not well defined. This study aims to assess the effect of resident involvement on short-term outcomes following anterior cruciate ligament reconstruction (ACLR). The National Surgical Quality Improvement Program (NSQIP) database was queried to identify all patients who underwent ACLR from 2005 to 2012. Demographic variables, resident participation, 30-day complications, and intraoperative time parameters were assessed for all cases. Resident and nonresident cases were matched using propensity scores. Outcomes were analyzed using univariate and multivariate regression analyses, as well as stratified by resident level of training. Univariate analysis of 1,222 resident and 1,188 nonresident cases demonstrated no difference in acute postoperative complication rates between groups. There was no significant difference in the incidence of overall complications based on resident level of training (p = 0.109). Operative time was significantly longer for cases in which a resident was involved (109.5 vs. 101.7 minutes; p < 0.001). Multivariate analysis identified no significant predictors of major postoperative complications, while patient history of chronic obstructive pulmonary disease was the only independent risk factor associated with minor complications. Resident involvement in ACLR was not associated with 30-day complications despite a slight increase in operative time. These findings provide reassurance that resident involvement in ACLR procedures is safe, although future investigations should focus on long-term postoperative outcomes.

Five-Strand Versus Four-Strand Hamstring Autografts in Anterior Cruciate Ligament Reconstruction-A Prospective Randomized Controlled Study

PURPOSE

To compare the clinical outcomes of the routine use of 5-strand hamstring grafts (where possible) with those of 4-strand grafts in primary anterior cruciate ligament (ACL) reconstruction.

METHODS

A total of 64 patients were enrolled in a prospective randomized controlled study comparing the use of 5-strand and 4-strand semitendinosus-gracilis autografts in single bundle ACL reconstruction (n = 32 in each group). Four participants in each group were lost to follow-up and were excluded from the outcome analysis. The outcomes of 28 patients in the 5-strand group and 28 patients in the 4-strand group were analyzed. The diameters of all grafts were measured intraoperatively. Patients were assessed postoperatively at 2 years with objective assessments (anterior knee laxity using the KT-2000 arthrometer, Lachman test, pivot-shift test, hop test) and patient-reported outcome scores (Lysholm knee score, Knee Injury and Osteoarthritis Outcome Score, International Knee Documentation Committee subjective knee score, SF-36 physical and mental components, Tegner activity scale). Postoperative graft ruptures were also noted.

RESULTS

There were improvements in all outcome measures postoperatively regardless of the number of graft strands. When we compared the study and control groups, there were no significant differences in all subjective and objective outcome measures except the Knee Injury and Osteoarthritis Outcome Score symptoms score (5-strand group 93.3 ± 9.2 vs 4-strand group 86.2 ± 14.7, P = .04). The KT-2000 side-to-side difference was 2.79 ± 2.11 mm in the 5-strand group and 2.54 ± 1.75 mm in the 4-strand group (P = .63). The 5-strand study group had 2 graft ruptures at 1 year, whereas the 4-strand control group had one partial graft rupture at 6 months.

CONCLUSIONS

At 2-year follow-up, the routine use of the 5-strand hamstring tendon autograft was not superior to that of the quadrupled or 4-strand graft in primary ACL reconstruction.

LEVEL OF EVIDENCE

Level I, prospective randomized controlled trial.

Risk Factors for Contra-Lateral Secondary Anterior Cruciate Ligament Injury: A Systematic Review with Meta-Analysis

Background

The risk of sustaining a contra-lateral anterior cruciate ligament (C-ACL) injury after primary unilateral ACL injury is high. C-ACL injury often contributes to a further decline in function and quality of life, including failure to return to sport. There is, however, very limited knowledge about which risk factors that contribute to C-ACL injury.

Objective

To systematically review instrinsic risk factors for sustaining a C-ACL injury.

Methods

A systematic review with meta-analysis was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Four databases (MEDLINE, CINAHL, EMBASE, Sport Discus) were searched from inception to January 2020. Inclusion criteria were prospective or retrospective studies investigating any intrinsic risk factor for future C-ACL injury. Meta-analysis was performed and expressed as odds ratios (OR) if two or more articles assessed the same risk factor.

Results

44 moderate-to-high quality studies were eventually included in this review, whereof 35 studies were eligible for meta-analysis, including up to 59 000 individuals. We identified seven factors independently increasing the odds of sustaining a C-ACL injury (in order of highest to lowest OR): (1) returning to a high activity level (OR 3.26, 95% CI 2.10–5.06); (2) Body Mass Index < 25 (OR 2.73, 95% CI 1.73–4.36); (3) age ≤ 18 years (OR 2.42, 95% CI 1.51–3.88); (4) family history of ACL injury (OR 2.07, 95% CI 1.54–2.80); (5) primary ACL reconstruction performed ≤ 3 months post injury (OR 1.65, 95% CI: 1.32–2.06); (6) female sex (OR 1.35, 95% CI 1.14–1.61); and (7) concomitant meniscal injury (OR 1.21, 95% CI 1.03–1.42). The following two factors were associated with decreased odds of a subsequent C-ACL injury: 1) decreased intercondylar notch width/width of the distal femur ratio (OR 0.43, 95% CI 0.25–0.69) and 2) concomitant cartilage injury (OR 0.83, 95% CI 0.69–1.00). There were no associations between the odds of sustaining a C-ACL injury and smoking status, pre-injury activity level, playing soccer compared to other sports or timing of return to sport. No studies of neuromuscular function in relation to risk of C-ACL injury were eligible for meta-analysis according to our criteria.

Conclusion

This review provides evidence that demographic factors such as female sex, young age (≤ 18 years) and family history of ACL injury, as well as early reconstruction and returning to a high activity level increase the risk of C-ACL injury. Given the lack of studies related to neuromuscular factors that may be modifiable by training, future studies are warranted that investigate the possible role of factors such as dynamic knee stability and alignment, muscle activation and/or strength and proprioception as well as sport-specific training prior to return-to-sport for C-ACL injuries.

PROSPERO: CRD42020140129.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40279-020-01424-3.

Patellofemoral Dislocation Recurrence After a First Episode: A Case-Control Study

Background:

Lateral patellar dislocation can become a recurrent problem after the first episode. Identifying those patients who are at increased risk of redislocation is important for the treatment decision-making process.

Purpose:

To identify clinical and radiologic risk factors for recurrence of patellar dislocation after a first episode.

Study Design:

Case-control study; Level of evidence, 3.

Methods:

The study included patients with lateral patellar dislocation and a 1-year minimum follow-up who were seen between 2011 and 2018. Patients aged 10 to 65 years were included. Patient characteristics, physical examination (patellar apprehension, J sign), and radiographs were reviewed. The Caton-Deschamps and Insall-Salvati ratios were used to evaluate patella alta. High-grade trochlear dysplasia was defined as Dejour types B, C, and D.

Results:

A total of 130 patients (139 knees) with primary lateral patellar dislocation were included. Recurrent dislocation was seen in 83 knees (59.71%). Stepwise logistic regression analysis demonstrated that Caton-Deschamps ratio ≥1.15 (OR, 2.39; 95% CI, 1.09-5.22; P = .029), age <21 years (OR, 2.53; 95% CI, 1.11-5.77; P = .027), and high-grade trochlear dysplasia (OR, 4.17; 95% CI, 1.90-9.17; P < .001) were significantly associated with patellar redislocation. Based on the presence of these factors, the probability of dislocation after a first lateral patellar dislocation was 31.2% with no factors present, 36.6% with any 1 factor present, 71.7% with any 2 factors present, and 86.2% if all 3 conditions were present.

Conclusion:

The results of this study indicated that patella alta, high-grade trochlear dysplasia, and age <21 years were independent risk factors for patellar redislocation after a first episode, with an additive effect when they were present together. This may help to guide the type of treatment for these patients.

Effect of Graft Rupture Prevention Training on Young Athletes After Anterior Cruciate Ligament Reconstruction: An 8-Year Prospective Intervention Study

Background:

There is a lack of research on the effects of a postoperative rehabilitation program on anterior cruciate ligament (ACL) graft rupture.

Hypothesis:

We hypothesized that a hip-focused rehabilitation protocol with graft rupture education and avoidance training (HIP-GREAT program) would demonstrate lower ACL graft rupture rates compared with a traditional physical therapy (PT) program.

Study Design:

Cohort study; Level of evidence, 3.

Methods:

This study consisted of young athletes who had undergone ACL reconstruction at a single institution. Postoperatively, 136 participants (mean age, 16.9 ± 2.4 years) were enrolled in a traditional PT protocol between 2006 and 2010, and 153 participants (mean age, 17.0 ± 2.3 years) were enrolled in the HIP-GREAT protocol between 2011 and 2015. Follow-up rates were 31% (42/136) and 27% (41/153) in the traditional PT and HIP-GREAT groups, respectively, at 3 years postoperatively. The hazard ratio was calculated, and absolute risk reduction (ARR) and number-needed-to-treat (NNT) analyses were performed to compare the 2 protocols.

Results:

ACL graft rupture occurred in 10 patients (7.4%) in the traditional PT group and 5 patients (3.3%) in the HIP-GREAT group. This difference was not statistically significant (hazard ratio, 0.39; 95% CI, 0.14 to 1.16; P = .09). The ARR was 0.041 (95% CI, –0.011 to 0.093), and the NNT was 24.5.

Conclusion:

This study did not demonstrate a statistically significant reduction of ACL graft rupture in patients in the HIP-GREAT group. However, high ARR values and low NNT values were found, which suggests the possible effectiveness of the HIP-GREAT protocol to reduce ACL graft ruptures in young athletes.

An arthroscopic repair technique for proximal anterior cruciate tears in children to restore active function and avoid growth disturbances

PURPOSE

The aim of this study was to assess midterm clinical outcomes in Tanner 1-2 patients with proximal anterior cruciate ligament (ACL) tears following arthroscopic-surgical repair using an absorbable or an all-suture anchor.

METHODS

Fourteen (9.2 ± 2.9 years-old) of 19 skeletally immature patients reached the 2 years of clinical follow-up. Physical examinations included the Lachman test, Pivot-shift test, One-leg Hop test, Pedi-IKDC as well as Lysholm and Tegner activity scores; knee stability was measured with a KT-1000 arthrometer. Overall re-rupture rates were also evaluated in all operated patients.

RESULTS

At 2 years post-surgery, the Lysholm score was 93.6 ± 4.3 points, and the Pedi-IKDC score was 95.7 ± 0.1. All patients returned to the same sport activity level as prior to ACL lesion within 8.5 ± 2.9 months, with one exception who reported a one-point reduction in their Tegner Activity score. No leg-length discrepancies or malalignments were observed. Four patients presented grade 1 Lachman scores, and of these, three presented grade 1 (glide) score at Pivot-shift; clinical stability tests were negative for all other patients. Anterior tibial shift showed a mean side-to-side difference of 2.2 mm (range 1-3 mm). The One-leg Hop test showed lower limb symmetry (99.9% ± 9.5) with the contralateral side. Overall, 4 out of 19 patients presented a re-rupture of the ACL with a median time between surgery and re-rupture of 3.9 years (range 1-7).

CONCLUSION

This surgical technique efficiently repairs proximal ACL tears, leading to a restoration of knee stability and a quick return to an active lifestyle, avoiding growth plate disruption.

LEVEL OF EVIDENCE

IV.

Knee laxity and functional knee outcome after contralateral ACLR are comparable to those after primary ACLR

PURPOSE

To evaluate and compare knee laxity and functional knee outcome between primary and contralateral anterior cruciate ligament (ACL) reconstruction.

METHODS

Patients who underwent primary and subsequent contralateral ACL reconstruction (ACLR) at Capio Artro Clinic, Stockholm, Sweden, from 2001 to 2017, were identified in our local database. The inclusion criteria were: the same patients who underwent primary and contralateral hamstring tendon or bone-patellar tendon-bone autograft ACLR and no associated ligament injuries. The KT-1000 arthrometer, with an anterior tibial load of 134 N, was used to evaluate knee laxity preoperatively and 6 months postoperatively. The Knee injury and Osteoarthritis Outcome Score (KOOS) was collected preoperatively and at the 1-year follow-up.

RESULTS

A total of 326 patients with isolated primary and contralateral ACLR met the inclusion criteria (47.9% males; mean age at primary ACLR 23.9 ± 9.4 years and contralateral ACLR 27.9 ± 10.1 years). The arthrometric laxity measurements were available for primary and contralateral ACLR for 226 patients. The mean preoperative and postoperative anterior tibial translation (ATT), as well as the mean ATT reduction from preoperatively to postoperatively, did not differ significantly between primary and contralateral ACLR. The KOOS was available for primary and contralateral ACLR for 256 patients. No significant differences were found preoperatively and at the 1-year follow-up between primary and contralateral ACLR for any of the five KOOS subscales.

CONCLUSION

The findings in this study showed that anterior knee laxity and functional knee outcome after contralateral ACLR are comparable to those after primary ACLR. It is important for clinicians to counsel patients about their expectations after contralateral ACLR. This study shows that the results after contralateral ACLR in terms of knee laxity and functional knee outcome are predictable and likely to be comparable to those after primary ACLR.

LEVEL OF EVIDENCE

Level III.

Analysis of copy number variation in dogs implicates genomic structural variation in the development of anterior cruciate ligament rupture

Anterior cruciate ligament (ACL) rupture is an important condition of the human knee. Second ruptures are common and societal costs are substantial. Canine cranial cruciate ligament (CCL) rupture closely models the human disease. CCL rupture is common in the Labrador Retriever (5.79% prevalence), ~100-fold more prevalent than in humans. Labrador Retriever CCL rupture is a polygenic complex disease, based on genome-wide association study (GWAS) of single nucleotide polymorphism (SNP) markers. Dissection of genetic variation in complex traits can be enhanced by studying structural variation, including copy number variants (CNVs). Dogs are an ideal model for CNV research because of reduced genetic variability within breeds and extensive phenotypic diversity across breeds. We studied the genetic etiology of CCL rupture by association analysis of CNV regions (CNVRs) using 110 case and 164 control Labrador Retrievers. CNVs were called from SNPs using three different programs (PennCNV, CNVPartition, and QuantiSNP). After quality control, CNV calls were combined to create CNVRs using ParseCNV and an association analysis was performed. We found no strong effect CNVRs but found 46 small effect (max(T) permutation P<0.05) CCL rupture associated CNVRs in 22 autosomes; 25 were deletions and 21 were duplications. Of the 46 CCL rupture associated CNVRs, we identified 39 unique regions. Thirty four were identified by a single calling algorithm, 3 were identified by two calling algorithms, and 2 were identified by all three algorithms. For 42 of the associated CNVRs, frequency in the population was <10% while 4 occurred at a frequency in the population ranging from 10–25%. Average CNVR length was 198,872bp and CNVRs covered 0.11 to 0.15% of the genome. All CNVRs were associated with case status. CNVRs did not overlap previous canine CCL rupture risk loci identified by GWAS. Associated CNVRs contained 152 annotated genes; 12 CNVRs did not have genes mapped to CanFam3.1. Using pathway analysis, a cluster of 19 homeobox domain transcript regulator genes was associated with CCL rupture (P = 6.6E-13). This gene cluster influences cranial-caudal body pattern formation during embryonic limb development. Clustered genes were found in 3 CNVRs on chromosome 14 (HoxA), 28 (NKX6-2), and 36 (HoxD). When analysis was limited to deletion CNVRs, the association was strengthened (P = 8.7E-16). This study suggests a component of the polygenic risk of CCL rupture in Labrador Retrievers is associated with small effect CNVs and may include aspects of stifle morphology regulated by homeobox domain transcript regulator genes.

Development of pluripotent stem cell-based human tenocytes

Human pluripotent stem cells (PSCs) are used as a platform for therapeutic purposes such as cell transplantation therapy and drug discovery. Another motivation for studying PSCs is to understand human embryogenesis and development. All cell types that make up the body tissues develop through defined trajectories during embryogenesis. For example, paraxial mesoderm is considered to differentiate into several cell types including skeletal muscle cells, chondrocytes, osteocytes, dermal fibroblasts, and tenocytes. Tenocytes are fibroblast cells that constitute the tendon. The step-wise narrowing fate decisions of paraxial mesoderm in the embryo have been modeled in vitro using PSCs; however, deriving tenocytes from human-induced PSCs and their application in cell therapy have long been challenging. PSC-derived tenocytes can be used for a source of cell transplantation to treat a damaged or ruptured tendon due to injury, disorder, or aging. In this review, we discuss the latest research findings on the use of PSCs for studying the biology of tenocyte development and their application in therapeutic settings.

Patient-Related Risk Factors for Contralateral Anterior Cruciate Ligament (ACL) Tear After ACL Reconstruction: An Analysis of 3707 Primary ACL Reconstructions

BACKGROUND

Return to play after anterior cruciate ligament (ACL) reconstruction can increase risk for both ipsilateral graft rupture and contralateral ACL rupture. The risk for injury of the contralateral knee after ACL reconstruction could be nearly double that of ipsilateral graft rupture.

QUESTIONS/PURPOSES

We sought to identify independent, patient-related risk factors for contralateral ACL rupture following primary ACL reconstruction.

METHODS

A national database was queried for patients who underwent primary ACL reconstruction from 2007 to 2015 with a minimum of 2 years of post-operative follow-up (n = 12,044). Patients who underwent subsequent primary ACL reconstruction on the contralateral extremity were then identified. A multivariate binomial logistic regression analysis was utilized to evaluate patient-related risk factors for contralateral ACL rupture, including demographic and comorbidity variables. Adjusted odds ratios and 95% confidence intervals were calculated for each risk factor.

RESULTS

Of the 3707 patients who had a minimum of 2 years of database activity and comprised the study group, 204 (5.5%) experienced a contralateral ACL rupture requiring reconstruction. Independent risk factors for contralateral ACL rupture included age less than 20 years, female gender, tobacco use, and depression. Obesity, morbid obesity, type 1 diabetes, type 2 diabetes, and a history of anxiety were not significant predictors of contralateral injury.

CONCLUSION

We were able to adequately power an analysis to identify several significant patient-related risk factors for contralateral ACL rupture after primary ACL reconstruction, including younger age, female gender, tobacco use, and depression. This information can be used to counsel patients on the risk of injury to the contralateral knee.

Failed Meniscal Repairs After Anterior Cruciate Ligament Reconstruction Increases Risk of Revision Surgery

Background:

Failed anterior cruciate ligament (ACL) reconstruction (ACLR) can lead to reduced quality of life because of recurrent episodes of instability, restrictions in level of activity, and development of osteoarthritis. A profound knowledge of the causes of a failed surgery can ultimately help improve graft survival rates.

Purpose:

To investigate the patient-related risks of inferior outcomes leading to revision surgery after ACLR.

Study Design:

Case-control study; Level of evidence, 3.

Methods:

From a prospective cohort of primary ACLRs performed at a single center, patients who required later revision surgery were matched with a control group of uneventful primary ACLRs. Patient characteristics, data from the preoperative examinations, KT-1000 arthrometer laxity testing, Tegner activity scale, International Knee Documentation Committee subjective score, Knee injury and Osteoarthritis Outcome Score, and perioperative data from the initial surgery were included.

Results:

A total of 100 revision cases and 100 matched controls, with a median follow-up time of 11 years, were included in the study. Those who had undergone revision surgery were younger at the time of reconstruction and had a shorter time from injury to surgery than their matched controls (P = .006). The control group—of uneventful ACLRs—had a higher incidence of meniscal repair at reconstruction (P = .024). Also, the revision group more frequently experienced later failure of the previous meniscal repair (P = .004). Surgeon experience was not found to affect the risk of revision ACL surgery. Those who had undergone ACL revision surgery had more frequently received a hamstring tendon graft size of <8 mm (P = .018) compared with the controls.

Conclusion:

The current study demonstrated that failed meniscal repair and a hamstring tendon graft size of <8 mm were associated with primary ACLR failure. Also, younger age at the time of surgery and shorter time from injury to surgery were found to affect the risk of undergoing revision ACL surgery.

Trauma and femoral tunnel position are the most common failure modes of anterior cruciate ligament reconstruction: a systematic review

PURPOSE

To improve outcomes of anterior cruciate ligament reconstruction (ACLR), it is important to understand the reasons for failure of this procedure. This systematic review was performed to identify current failure modes of ACLR.

METHODS

A systematic search was performed using PubMed, EMBASE, Cochrane, and annual registries for ACLR failures. Studies were included when failure modes were reported (I) of ≥ 10 patients and (II) at a minimum of two-year follow-up. Modes of failure were also compared between different graft types and in femoral tunnel positions.

RESULTS

This review included 24 cohort studies and 4 registry-based studies (1 level I, 1 level II, 10 level III, and 16 level IV studies). Overall, a total of 3657 failures were identified. The most common single failure mode of ACLR was new trauma (38%), followed by technical errors (22%), combined causes (i.e. multiple failure mechanisms; 19%), and biological failures (i.e. failure due to infection or laxity without traumatic or technical considerations; 8%). Technical causes also played a contributing role in 17% of all failures. Femoral tunnel malposition was the most common cause of technical failure (63%). When specifically looking at the bone-patellar tendon-bone (BPTB) or hamstring (HT) autografts, trauma was the most common failure mode in both, whereas biological failure was more pronounced in the HT group (4% vs. 22%, respectively). Technical errors were more common following transtibial as compared to anteromedial portal techniques (49% vs. 26%).

CONCLUSION

Trauma is the single leading cause of ACLR failure, followed by technical errors, and combined causes. Technical errors seemed to play a major or contributing role in large part of reported failures, with femoral tunnel malposition being the leading cause of failure. Trauma was also the most common failure mode in both BPTB and HT grafts. Technical errors were a more common failure mode following transtibial than anteromedial portal technique.

LEVEL OF EVIDENCE

IV.

Clinical outcome and failure analysis of medial meniscus bucket-handle tear repair: a series of 96 patients with a minimum 2 year follow-up

INTRODUCTION

The failure rate of meniscal repair remains significant, especially for bucket-handle tears. This study aimed to evaluate the clinical outcomes, failure rate and risk factors for failure of bucket-handle medial meniscal tear repairs performed during ACL reconstruction.

MATERIALS AND METHODS

A retrospective analysis of prospectively collected data was performed on a consecutive series of 96 ACL reconstructions with meniscal arthroscopic suture of a bucket-handle tear of the medial meniscus with a minimum 2 year follow-up. Preoperative and postoperative evaluation at last follow-up included objective IKDC rating, instrumented differential laxity and Tegner activity level. Functional outcome was evaluated with Lysholm score at last follow-up. Failure rate, survival curves and risk factor analysis using Cox proportional hazard ratio models were performed to analyze suture repair failure.

RESULTS

At IKDC rating, all patients were C or D preoperatively, whereas they where all A or B at last follow-up. Instrumented differential laxity improved from 6.77 mm (1.57) to 1.02 mm (1.15) mm at last follow-up (p = 1.9 E^-18). The mean Tegner score before injury was 6.79 (± 1.47) and 6.11 (± 1.75) at last follow-up (p = 0.0011). Mean Lyholm score at last follow-up was 91.53 (± 11.6). The average entire cohort failure rate was 19% at final follow-up of 35.2 ± 9.8 months. Kaplan-Meier survival analysis demonstrated that the probability of the absence of failure decreased constantly over time. No significant difference in the objective IKDC, Lysholm or Tegner scores was observed between the failure group and the success group. Multivariate analysis revealed that younger patients and a procedure of ACL revision are more at risk for suture repair failure. In the majority of cases, the meniscal lesion observed at revision was equivalent or less extensive than the initial lesion.

CONCLUSION

Despite the fact that failure rate remains high for medial meniscus bucket-handle tears, suture repair of bucket-handle tears should be encouraged taking into account the long-term consequences of menisectomy.

Return to sports bridge program improves outcomes, decreases ipsilateral knee re-injury and contralateral knee injury rates post-ACL reconstruction

PURPOSE

To present the results of a return to sports bridge program designed to reduce knee injuries following ACL reconstruction and physical therapy.

METHODS

One hundred and fifty (male = 83, female = 67) patients participated in a whole body neuromuscular control, progressive resistance strength and agility training program. Post-program testing included functional movement form, dynamic knee stability, lower extremity power, agility, and sports skill assessments. Participants completed the Knee Outcome Survey-Sports Activity Scale (KOS-SAS) before and after program initiation. Pre-participation scores were re-estimated following program completion.

RESULTS

Global rating KOS-SAS score at program entry was 75 ± 13. Post-program global rating and calculated KOS-SAS were 91.0 ± 9.8 and 90.9 ± 9.7, respectively (p < 0.0001). Pre-participation KOS-SAS score re-estimates at program completion were 54.5 ± 23.3 and 57.3 ± 18.5, respectively. The approximately 20% lower pre-program KOS-SAS score re-estimates (p < 0.0001) observed at program completion suggests that subjects had inaccurately high sports readiness perceptions at program entry. Perceived overall sports activity knee function ratings improved from 2.9 ± 0.6 (abnormal) at program entry to 1.3 ± 0.5 (normal) at completion (p < 0.0001). Most subjects returned back to sports at or above their pre-injury performance skill/performance level (84%, 126/150). By 6.8 ± 3.2 years (range = 2-13 years) post-surgery, ten subjects had sustained an ipsilateral knee re-injury or contralateral knee injury (6.7%). The 2.7% non-contact contralateral and 1.3% non-contact ipsilateral knee injury rates observed were significantly lower than those cited in previous reports.

CONCLUSION

Supplementing primary ACL reconstruction and standard physical therapy with a return to sports bridge program prior to release to unrestricted sports performance was effective at improving patient outcomes and decreasing ipsilateral knee re-injury and contralateral knee injury rates.

LEVEL OF EVIDENCE

II.

Anterior cruciate ligament reconstruction with bone-patellar tendon-bone graft is associated with higher and earlier return to sports as compared to hamstring tendon graft

PURPOSE

To study the effect of age, duration of injury, type of graft and concomitant knee injuries on return to sports after anterior cruciate ligament (ACL) reconstruction.

METHOD

One-hundred and sixteen athletes underwent ACL reconstruction using either bone-patellar tendon-bone graft (BPTB; n = 58) or semitendinosus-gracilis graft (n = 58), depending upon their random number sequences. Five variables were analyzed in terms of their effect on return to sports-age, type of graft, time interval between injury and surgery, chondral damage and meniscal tears.

RESULTS

Fifty-three out of 73 (72.6%) athletes aged between 16 and 25 years and 21/43 (49%) athletes aged between 25 and 40 years returned to sports (p = 0.02). The mean time to return to sports was 9.7 ± 2.1 months and 10.8 ± 1.7 months in athletes aged < 25 years and 25-40 years, respectively (p = 0.04). ACL reconstruction with BPTB graft (43/58) was associated with higher rate of return to sports as compared to hamstring tendon graft (31/58; p = 0.02). The mean duration of return to sports with BPTB and STGPI graft was 9.7 ± 2.0 months and 10.7 ± 2.0 months, respectively (p = 0.02). 29/36 (80.5%) patients operated between 2 and 6 months, 18/29 (62%) operated in < 2 months, and 27/51 (53%) operated after 6 months of injury had returned to sports (p = 0.03). Athletes who were operated within 2 months of the injury were the earliest to return to sports (9.4 ± 2.1 months), followed by those operated within 2-6 months (9.9 ± 1.9 months) and lastly by the ones operated after 6 months of the injury (10.9 ± 2.1 months; p = 0.04).

CONCLUSIONS

The rate of return to sports was observed to be higher in athletes younger than 25 years as compared to older athletes (> 25 years). ACL reconstruction with BPTB graft was associated with higher and earlier returns to sports as compared to hamstring graft. The rate of return to sports was highest if surgery was performed between 2 and 6 months after the injury.

LEVEL OF EVIDENCE

III.

Neuromuscular Training Improves Self-Reported Function and Single-Leg Landing Hip Biomechanics in Athletes After Anterior Cruciate Ligament Reconstruction

Background:

Neuromuscular training (NMT) has been shown to attenuate high-risk biomechanics in uninjured athletes. At the time that athletes return to sport after anterior cruciate ligament (ACL) reconstruction (ACLR), they demonstrate hip biomechanical deficits associated with injury to the reconstructed knee versus the uninjured contralateral knee.

Purpose:

The primary purpose of the study was to examine whether an NMT program can improve single-leg drop (SLD) landing hip biomechanics for athletes after ACLR. Secondarily, we compared the posttraining SLD hip biomechanics of athletes after ACLR with a control group of athletes who also completed the NMT program.

Study Design:

Controlled laboratory study.

Methods:

A total of 18 ACLR and 10 uninjured athletes were recruited and completed a 12-session NMT program. A knee-specific questionnaire and biomechanics of an SLD task was evaluated for each athlete before and after NMT. Paired t tests were used to compare pre- and posttraining International Knee Documentation Committee (IKDC) scores. Repeated-measures analysis of variance (ANOVA) was performed to assess the main effects and interactions of testing session × limb for the ACLR athletes. A 2-way ANOVA was conducted to quantify the interactions and main effects of group × limb.

Results:

There was a significant increase (P = .03) in IKDC scores from pre- to posttraining. For the ACLR athletes, there was a significant session × limb interaction for hip external rotation moment (P = .02) and hip abduction angle (P = .013). Despite increases in hip external rotation moment, no significant changes from pre- to posttraining were observed for the involved limbs. No significant changes were observed for hip abduction angle of the involved limbs between training sessions. Significant main effects of session (P < .05) revealed that athletes landed with greater hip excursion, lower hip flexion moment, and lower ground-reaction force after training. The posttraining comparison between the ACLR and control groups found no significant group × limb interactions for any of the hip kinematic or kinetic variables. A significant main effect of group (P < .05) revealed that the ACLR athletes landed with greater hip flexion angle and hip external rotation moment.

Conclusion:

ACLR athletes demonstrated an improvement in SLD hip biomechanics and neuromuscular control after participating in an NMT program.

Clinical Relevance:

This evidence indicates a potential role for NMT to improve hip biomechanics during an SLD task so as to reduce ACL injury risk.

Prospective Frontal Plane Angles Used to Predict ACL Strain and Identify Those at High Risk for Sports-Related ACL Injury

Background:

Knee abduction moment during landing has been associated with anterior cruciate ligament (ACL) injury. However, accurately capturing this measurement is expensive and technically rigorous. Less complex variables that lend themselves to easier clinical integration are desirable.

Purpose:

To corroborate in vitro cadaveric simulation and in vivo knee abduction angles from landing tasks to allow for estimation of ACL strain in live participants during a landing task.

Study Design:

Descriptive laboratory study.

Methods:

A total of 205 female high school athletes previously underwent prospective 3-dimensional motion analysis and subsequent injury tracking. Differences in knee abduction angle between those who went on to develop ACL injury and healthy controls were assessed using Student t tests and receiver operating characteristic analysis. A total of 11 cadaveric specimens underwent mechanical impact simulation while instrumented to record ACL strain and knee abduction angle. Pearson correlation coefficients were calculated between these variables. The resultant linear regression model was used to estimate ACL strain in the 205 high school athletes based on their knee abduction angles.

Results:

Knee abduction angle was greater for athletes who went on to develop injury than for healthy controls (P < .01). Knee abduction angle at initial contact predicted ACL injury status with 78% sensitivity and 83% specificity, with a threshold of 4.6° of knee abduction. ACL strain was significantly correlated with knee abduction angle during cadaveric simulation (P < .01). Subsequent estimates of peak ACL strain in the high school athletes were greater for those who went on to injury (7.7-8.1% ± 1.5%) than for healthy controls (4.1-4.5% ± 3.6%) (P < .01).

Conclusion:

Knee abduction angle exhibited comparable reliability with knee abduction moment for ACL injury risk identification. Cadaveric simulation data can be extrapolated to estimate in vivo ACL strain. Athletes who went on to ACL injury exhibited greater knee abduction and greater ACL strain than did healthy controls during landing.

Clinical Relevance:

These important associations between the in vivo and cadaveric environments allow clinicians to estimate peak ACL strain from observed knee abduction angles. Neuromuscular control of knee abduction angle during dynamic tasks is imperative for knee joint health. The present associations are an important step toward the establishment of a minimal clinically important difference value for ACL strain during landing.

Clinical and Radiographic Outcomes of Anterior Cruciate Ligament Reconstruction With Hamstring Tendon Graft and Femoral Cortical Button Fixation at Minimum 20-Year Follow-up

BACKGROUND

The short-term outcomes of anterior cruciate ligament (ACL) reconstruction with bone-patellar tendon-bone or hamstring tendon (HT) graft are excellent with good clinical stability and patient-reported outcomes. Although some studies have reported the long-term outcomes of bone-patellar tendon-bone graft ACL reconstruction, few have reported the outcomes of HT graft ACL reconstruction.

PURPOSE

To assess clinical and radiographic outcomes of HT graft ACL reconstruction with femoral cortical button fixation at a minimum 20-year follow-up.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

A prospective study was performed in which all patients undergoing isolated transtibial primary ACL reconstruction between 1994 and 1996 with HT graft and femoral cortical button fixation were assessed clinically and radiographically. Follow-up was obtained in 48 of 94 patients (51%). Median (interquartile range) age at operation was 31 years (26-39 years); median follow-up was 21 years (20-22 years); 65% were male; and 48% had meniscal injury at surgery and underwent partial meniscectomy. Graft rupture, reoperation, and contralateral injury rates were assessed; clinical stability was measured using the KT-1000 arthrometer; patient-reported outcomes were assessed (International Knee Documentation Committee [IKDC], Lysholm, Forgotten Joint Score, Tegner activity, Knee injury and Osteoarthritis Outcome Score [KOOS], Anterior Cruciate Ligament Quality of Life [ACL-QOL], EuroQol 5-Dimension 5-Level [EQ-5D-5L]); and radiographic osteoarthritis (defined as Kellgren-Lawrence grade ≥2) was assessed for the ipsilateral and the contralateral knee.

RESULTS

Graft rupture occurred in 4 patients (8%), contralateral injury in 4 patients (8%), and reoperation in 15 patients (31%), which consisted mainly of meniscal tears or hardware removal. In patients with an intact graft, excellent patient-reported outcome measures (PROMs) were noted, with a median Lysholm of 90 (78-100), subjective IKDC of 86 (72-95), and KOOS-Sports of 86 (58-100). There was low awareness of the operated knee (Forgotten Joint Score, 81 [60-96]) and good quality of life (ACL-QOL, 85 [75-94]; EQ-5D-5L, 0.87 [0.83-1.00]). Median side-to-side difference, as measured with the KT-1000 arthrometer, was 1 mm (-1 to 3 mm). Radiographic osteoarthritis was evident in 49% of ipsilateral and 10% of contralateral knees and was associated with meniscectomy at index surgery and decreased PROMs at follow-up.

CONCLUSION

Long-term outcomes of transtibial HT graft ACL reconstruction with femoral cortical button fixation are generally good with a low failure rate, low awareness of the operated knee, and good clinical stability. Radiographic osteoarthritis was evident in approximately half of the patients at 20-year follow-up and was associated with meniscectomy at index surgery and decreased PROMs at follow-up.

Failure Rates of Autograft and Allograft ACL Reconstruction in Patients 19 Years of Age and Younger: A Systematic Review and Meta-Analysis

BACKGROUND

Graft choice for pediatric anterior cruciate ligament reconstruction (ACLR) is determined by several factors. There is limited information on the use and outcomes of allograft ACLR in pediatric patients. The purpose of this systematic review and meta-analysis was to quantify reported failure rates of allograft versus autograft ACLR in patients ≤19 years of age with ≥2 years of follow-up. We hypothesized that there would be higher rates of failure for allograft compared with autograft ACLR in this population.

METHODS

PubMed/MEDLINE and Embase databases were systematically searched for literature regarding allograft and autograft ACLR in pediatric/adolescent patients. Articles were included if they described a cohort of patients with average age of ≤19 years, had a minimum of 2 years of follow-up, described graft failure as an outcome, and had a Level of Evidence grade of I to III. Qualitative review and quantitative meta-analysis were performed to compare graft failure rates. A random-effects model was created to compare failure events in patients receiving allograft versus autograft in a pairwise fashion. Data analysis was completed using RevMan 5.3 software (The Cochrane Collaboration).

RESULTS

The database search identified 1,604 studies; 203 full-text articles were assessed for eligibility. Fourteen studies met the inclusion criteria for qualitative review; 5 studies were included for quantitative meta-analysis. Bone-patellar tendon-bone (BTB) represented 58.2% (n = 1,012) of the autografts, and hamstring grafts represented 41.8% (n = 727). Hybrid allografts (autograft + supplemental allograft) represented 12.8% (n = 18) of all allograft ACLRs (n = 141). The unweighted, pooled failure rate for each graft type was 8.5% for BTB, 16.6% for hamstring, and 25.5% for allograft. Allografts were significantly more likely than autografts to result in graft failure (odds ratio, 3.87; 95% confidence interval, 2.24 to 6.69).

CONCLUSIONS

Allograft ACLR in pediatric and adolescent patients should be used judiciously, as existing studies revealed a significantly higher failure rate for allograft compared with autograft ACLR in this patient population. Additional studies are needed to improve the understanding of variables associated with the high ACLR failure rate among pediatric and adolescent patients.

LEVEL OF EVIDENCE

Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Combined Anterolateral Ligament Reconstruction and Capsular Reinforcement in the Skeletally Immature Knee

Graft failure after anterior cruciate ligament reconstruction remains a challenging complication in the pediatric population. The anterolateral ligament (ALL) contributes to rotational stability, and early evidence in adults suggests that ALL reconstruction may lower the risk of anterior cruciate ligament graft rupture. We present a technique for combined ALL reconstruction and anterolateral capsular reinforcement using iliotibial band autograft in skeletally immature patients. This procedure seeks to provide additional rotational stability in varying degrees of flexion while avoiding the physes and eliminating the need for implants.

Revision ACL Reconstruction in Adolescent Patients

Background:

High failure rates have been documented after anterior cruciate ligament reconstruction (ACLR) in pediatric patients, and revision surgery is indicated due to high activity levels of children and adolescents.

Purpose:

To define trends in revision ACLR in patients who underwent initial ACLR at younger than 18 years.

Study Design:

Case series; Level of evidence, 4.

Methods:

An electronic medical record was used to retrospectively identify revision ACLR procedures performed by 2 surgeons between the years 2010 and 2016 in patients younger than 18 years at initial reconstruction. Descriptive information, intraoperative findings, surgical techniques, and rehabilitation data were recorded from initial and revision surgeries. Descriptive statistics were used.

Results:

A total of 32 patients (17 girls, 15 boys) met the inclusion criteria, with a mean age of 15.8 years at initial reconstruction. For initial reconstructions, 15 patients underwent transphyseal procedures, 3 patients underwent adult-type procedures using an anatomic reconstruction technique that did not take into account the physis, and 2 patients underwent partial intraepiphyseal procedures. Graft types included hamstring autograft (n = 17), allograft (n = 5), hybrid (n = 4), and bone–patellar tendon–bone autograft (BTB; n = 3). Average primary reconstruction graft diameter was 8.0 mm (girls, 7.72 mm; boys, 8.36 mm; P = .045). After initial reconstruction, 10 patients had postoperative protocol noncompliance, and 8 patients reported delayed recovery. Mean time to retear was 565 days (range, 25-1539 days). At revision, BTB autograft was used in 50% (n = 16), followed by hamstring autograph (31.3%; n = 10) and allograft (12.5%; n = 4); mean graft diameter was 9.05 mm. Chondral surgery was more common during revision (25% for revision vs 0% for index; P = .031). There were 4 patients who required staged reconstruction with bone grafting. At mean final follow-up of 29.5 months (SD, 22.2 months), there were 3 graft failures (9.4%) and 5 contralateral ACL ruptures (15.6%).

Conclusion:

Most patients with ACL graft failure were adequately treated with a single revision. Conversion from a soft tissue graft to a BTB autograft was the most common procedure. Infrequently, patients required staged reconstructions. Providers should have a high index of suspicion for associated intra-articular injuries resulting from graft failure in adolescent patients.

Current Perspectives of the Australian Knee Society on Rehabilitation and Return to Sport After Anterior Cruciate Ligament Reconstruction

CONTEXT

The importance of rehabilitation and evaluation prior to return to sport (RTS) in patients undergoing anterior cruciate ligament reconstruction has been reported.

OBJECTIVE

This study sought to investigate current perspectives of Australian orthopedic surgeons on rehabilitation and RTS evaluation.

DESIGN

Survey.

PARTICIPANTS

Members of the Australian Knee Society.

MAIN OUTCOME MEASURES

A 14-question survey was disseminated to Australian Knee Society members (orthopedic surgeons) to investigate (1) preferred graft choice, (2) estimated retear rate, (3) importance of preoperative and postoperative rehabilitation, and (4) preferred timing of RTS and evaluation prior to RTS discharge.

RESULTS

Of all 85 Australian Knee Society members contacted, 86% (n = 73) responded. Overall, 66 respondents (90.4%) preferentially used hamstring tendon autografts. All surgeons estimated their retear rate to be ≤15%, with 31 (42.5%) <5%. Twenty-eight surgeons (38.4%) reported no benefit in preoperative rehabilitation. The majority of surgeons (82.2%-94.5%) reported that postoperative rehabilitation was important within various periods throughout the postoperative timeline. Most surgeons did not permit RTS until ≥9 months (n = 56, 76.7%), with 17 (23.3%) allowing RTS between 6 and 9 months. The most highly reported considerations for RTS clearance were time (90.4%), functional capacity (90.4%), and strength (78.1%). Most commonly, knee strength and/or function was assessed via referral to a preferred rehabilitation specialist (50.7%) or with the surgeon at their practice (11.0%).

CONCLUSIONS

This survey revealed variation in beliefs and practices surrounding rehabilitation and RTS evaluation. This is despite the current evidence demonstrating the benefit of preoperative and postoperative rehabilitation, as well as the emerging potential of RTS assessments consisting of strength and functional measures to reduce reinjury rates.

A Secondary Injury Prevention Program May Decrease Contralateral Anterior Cruciate Ligament Injuries in Female Athletes: 2-Year Injury Rates in the ACL-SPORTS Randomized Controlled Trial

OBJECTIVE

To determine whether the addition of perturbation training to a secondary injury prevention program reduces the rate of second anterior cruciate ligament (ACL) injury compared to the prevention program alone.

DESIGN

Single-blinded randomized controlled trial.

METHODS

Thirty-nine female athletes who intended to return to cutting/pivoting sports were enrolled 3 to 9 months after primary anterior cruciate ligament reconstruction (ACLR). Athletes were randomized to receive a training program of either progressive strengthening, agility, plyometrics, and prevention (SAPP) (n = 20) or SAPP plus perturbation training (n = 19); each had 10 sessions over 5 weeks. Occurrence and side of second ACL injury were recorded for 2 years after primary ACLR.

RESULTS

There were 9 second ACL injuries in the 2 years after ACLR. There was no statistically significant difference in rate or side of second ACL injury between the SAPP-plus-perturbation training and SAPP groups.

CONCLUSION

Adding perturbation training to a secondary ACL injury prevention program did not affect the rate of second ACL injury in female athletes. J Orthop Sports Phys Ther 2020;50(9):523-530. Epub 1 Aug 2020. doi:10.2519/jospt.2020.9407.

Contralateral Anterior Cruciate Ligament Injuries Following Index Reconstruction in the Pediatric Athlete

PURPOSE OF REVIEW

The purpose of this review is to discuss relevant anatomy and pathoanatomy in the knee following anterior cruciate ligament reconstruction, risk factors for contralateral ACL tear, and mechanisms of contralateral injuries in the pediatric population.

RECENT FINDINGS

Contralateral ACL rupture rates following ACL reconstruction (ACLR) range from 4% to 42%. Pediatric patients show increased risk compared with adults, likely due to inherent anatomical differences along with biomechanical and neuromuscular changes that occur in both the operative and contralateral knees following index ACLR. Pediatric athletes who return to sport more quickly have been found to be at increased risk for contralateral tears, as have athletes who participate in cutting and pivoting sports. Contralateral tears tend to occur via non-contact mechanisms. Pediatric patients are at increased risk of contralateral ACL injury following index ACL reconstruction compared with adults. Further study is warranted to determine appropriate biologic, functional, and rehabilitative parameters gauged toward preventing contralateral ACL tear while minimizing time lost from sport.

ACL injuries before 15 years of age: could the young become an athlete?

PURPOSE

The purpose of this study was to systematically assess the possibility for a patient younger than 15 to return to a competitive level of sport following an ACL injury.

METHODS

Four databases were analyzed (PubMed, MedLine, Cinahl, Cochrane Library and LISTA). The Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines were used to guide the screening of the literature. Studies about functional and surgical treatments were included with a minimum of 5 years of mean follow-up. Methodological quality of individual studies was assessed with the Methodological Index for Non-Randomized Studies scale.

RESULTS

Ten studies were included, corresponding to a total of 217 patients. All studies were retrospective with level 4 evidence. Seven studies reported results of a transphyseal technique reconstruction, two studies a physeal-sparing reconstruction, and one studied the results of a repair (« healing response »). Only one study compared functional treatment and surgery. The mean age of patients at the time of surgery was 12.29 years (range 2-16) with a mean follow-up of 7.9 years (range 5.5-18.3). Return to sport was possible for 80 to 100% of patients (average of 91.7%) at the final follow-up but the level for return to sport was reported in only four studies and found between 61 and 89% for return to the same level and at 42% for return to a competitive level. Evolution of the Tegner score was analyzed in five studies and was reported to decrease at the follow-up in three studies. ACL re-ruptures can be considered as failure of the graft (nine studies with surgical technique) and occurred with an average of 16%.

CONCLUSION

This review demonstrate that ACL reconstruction is superior to conservative treatment and 'healing response' in terms of revision rates and knee laxity. Return to sport is possible for more than 4/5 of patients but only two thirds of them were able to return to the same level or to competitive level, and failure rates of the graft were not superior to global population. However, qualities of included studies and variability of treatment limited the clinical application of results. Despite this, patients and parents should be informed that ACL injuries are lesions that may influence the level of sport at a 5-year follow-up.

LEVEL OF EVIDENCE

Level IV, systematic review.

Transphyseal anterior cruciate ligament reconstruction using living parental donor hamstring graft: excellent clinical results at 2 years in a cohort of 100 patients

PURPOSE

To determine outcomes of transphyseal ACL reconstruction using a living parental hamstring tendon allograft in a consecutive series of 100 children.

METHODS

One hundred consecutive juveniles undergoing ACL reconstruction with a living parental hamstring allograft were recruited prospectively and reviewed 2 years after ACL reconstruction with IKDC Knee Ligament Evaluation, and KT1000 instrumented laxity testing. Skeletally immature participants obtained annual radiographs until skeletal maturity, and long leg alignment radiographs at 2 years. Radiographic Posterior tibial slope was recorded.

RESULTS

Of 100 juveniles, the median age was 14 years (range 8-16) and 68% male. At surgery, 30 juveniles were graded Tanner 1 or 2, 21 were Tanner 3 and 49 were Tanner 4 or 5. There were no cases of iatrogenic physeal injury or leg length discrepancy on long leg radiographs at 2 years, despite a median increase in height of 8 cm. Twelve patients had an ACL graft rupture and 9 had a contralateral ACL injury. Of those without further ACL injury, 82% returned to competitive sports, IKDC ligament evaluation was normal in 52% and nearly normal in 48%. The median side to side difference on manual maximum testing with the KT1000 was 2 mm (range - 1 to 5). A radiographic PTS of 12° or more was observed in 49%.

CONCLUSIONS

ACL reconstruction in the juvenile with living parental hamstring tendon allograft is a viable procedure associated with excellent clinical stability, patient-reported outcomes and return to sport over 2 years. Further ACL injury to the reconstructed and the contralateral knee remains a significant risk, with identical prevalence observed between the reconstructed and contralateral ACL between 12 and 24 months after surgery.

LEVEL OF EVIDENCE

III (Cohort Study).

The effect of anterolateral ligament reconstruction on knee constraint: A computer model-based simulation study

BACKGROUND

To determine the influence of anterolateral ligament reconstruction (ALLR) on knee constraint through the analysis of knee abduction (valgus) moment when the knee is subjected to external translational (anterior) or rotational (internal) loads.

METHODS

A knee computer model simulated from a three-dimensional computed tomography scan of healthy male was implemented for this study. Three groups were designed: (1) intact knee, (2) combined Anterior Cruciate Ligament (ACL) and Antero-Lateral Complex (ALC) deficient knee, and (3) combined ACL and Antero- lateral Ligament (ALL) reconstructed knee. The reconstructed knee group was subdivided into four groups according to attachment of reconstructed anterolateral ligament to the femoral epicondyle. Each group of simulated knees was placed at 0°, 10°, 20°, 30°, 40° and 50° of knee flexion. For each position an external anterior (drawer) 90-N force or a five-newton meter internal rotation moment was applied to the tibia. The interaction effect between the group of knees and knee flexion angle (0-50°) on knee kinematics and knee abduction moment under external loads was tested.

RESULTS

When reconstructed knees were subjected to a 90-N anterior force or a five-newton meter internal rotation moment there was significant reduction in anterior translation and internal rotation compared with deficient knees. Only the ALLR procedure using posterior and proximal femoral attachment sites for graft fixation combined with ACL reconstruction allowed similar mechanical behavior to that observed in the intact knee.

CONCLUSIONS

Combined ACL and ALLR using a minimally invasive method in an anatomically reproducible manner prevents excessive anterior translation and internal rotation. Using postero-proximal femoral attachment tunnel for reconstruction of ALL does not produce overconstraint of the lateral tibiofemoral compartment.

Hamstring autograft versus patellar tendon autograft for anterior cruciate ligament reconstruction, which graft has a higher contralateral anterior cruciate ligament injury rate?: A meta-analysis of 5561 patients following the PRISMA guidelines

BACKGROUND

Contralateral anterior cruciate ligament (CACL) injury is one of the devastating complications after anterior cruciate ligament (ACL) reconstruction. Whether the risk of CACL tear is related to graft selection remains controversial due to contradictory results in studies. There are no meta-analyses to compare which graft has a higher CACL injury rate. Hence, this meta-analysis was conducted to compare the incidence of the CACL injury after ACL reconstruction with bone-patellar tendon-bone (BPTB) autografts compared with hamstring (HT) autografts.

METHODS

A comprehensive search of literature published between 1980 and January 2020 was performed using MEDLINE, EMBASE, Web of Science, and the Cochrane Library databases. RevMan 5.3 software was used for meta-analysis. The overall risk ratio (RR) was calculated using a fixed- or random-effects. The heterogeneity among the included results was analyzed by chi-square test with significance set at P < .10, and the heterogeneity was quantitatively detected by I-square tests.

RESULTS

Fifteen prospective comparative studies met inclusion criteria. In the BPTB group, the CACL rupture rate ranged from 1.8% to 30%, with a pooled percentage of 8.5%. In the HT group, the CACL rupture rate ranged from 0% to 14.4%, with a pooled percentage of 3.3%. The overall CACL rupture rate was 3.1% and ranged from 1.1% to 27.1%, with a pooled percentage of 4.9%. The pooled results indicate that there was a statistical significant difference in CACL rupture risk rate between BPTB and HT autograft. (RR, 1.53; 95% CL, 1.21-1.91; P = .0004).

CONCLUSION

This review showed that patients undergoing primary ACL reconstruction with BPTB autograft were more likely to have CACL rupture than patients treated with HT autograft.

Clinical Outcomes After Anterior Cruciate Ligament Injury: Panther Symposium ACL Injury Clinical Outcomes Consensus Group

A stringent outcome assessment is a key aspect of establishing evidence-based clinical guidelines for anterior cruciate ligament (ACL) injury treatment. To establish a standardized assessment of clinical outcome after ACL treatment, a consensus meeting including a multidisciplinary group of ACL experts was held at the ACL Consensus Meeting Panther Symposium, Pittsburgh, Pennsylvania, USA, in June 2019. The aim was to establish a consensus on what data should be reported when conducting an ACL outcome study, what specific outcome measurements should be used, and at what follow-up time those outcomes should be assessed. The group reached consensus on 9 statements by using a modified Delphi method. In general, outcomes after ACL treatment can be divided into 4 robust categories: early adverse events, patient-reported outcomes (PROs), ACL graft failure/recurrent ligament disruption, and clinical measures of knee function and structure. A comprehensive assessment after ACL treatment should aim to provide a complete overview of the treatment result, optimally including the various aspects of outcome categories. For most research questions, a minimum follow-up of 2 years with an optimal follow-up rate of 80% is necessary to achieve a comprehensive assessment. This should include clinical examination, any sustained reinjuries, validated knee-specific PROs, and health-related quality of life questionnaires. In the midterm to long-term follow-up, the presence of osteoarthritis should be evaluated. This consensus paper provides practical guidelines for how the aforementioned entities of outcomes should be reported and suggests the preferred tools for a reliable and valid assessment of outcome after ACL treatment.

Identifying potential patient-specific predictors for anterior cruciate ligament reconstruction outcome - a diagnostic in vitro tissue remodeling platform

Purpose

Upon anterior cruciate ligament (ACL) rupture, reconstruction is often required, with the hamstring tendon autograft as most widely used treatment. Post-operative autograft remodeling enhances graft rupture risk, which occurs in up to 10% of the patient population, increasing up to 30% of patients aged under 20 years. Therefore, this research aimed to identify potential biological predictors for graft rupture, derived from patient-specific tissue remodeling-related cell properties in an in vitro micro-tissue platform.

Methods

Hamstring tendon-derived cells were obtained from remnant autograft tissue after ACL reconstructions (36 patients, aged 12–55 years), and seeded in collagen I gels on a micro-tissue platform. Micro-tissue compaction over time – induced by altering the boundary constraints – was monitored. Pro-collagen I expression was assessed using ELISA, and protein expression of tenomodulin and α-smooth muscle actin were measured using Western blot. Expression and activity of matrix metalloproteinase 2 were determined using gelatin zymography.

Results

Only micro-tissues corresponding to younger patients occasionally released themselves from the constraining posts. Pro-collagen I expression was significantly higher in younger patients. Differences in α-smooth muscle actin and tenomodulin expression between patients were found, but these were age-independent. Active matrix metalloproteinase 2 expression was slightly more abundant in younger patients.

Conclusions

The presented micro-tissue platform exposed patient-specific remodeling-related differences between tendon-derived cells, with the micro-tissues that released from constraining posts and pro-collagen I expression best reflecting the clinical age-dependency of graft rupture. These properties can be the starting point in the quest for potential predictors for identifying individual patients at risk for graft rupture.

Rates of revision and surgeon-reported graft rupture following ACL reconstruction: early results from the New Zealand ACL Registry

PURPOSE

There remains a lack of consensus on the patient factors associated with graft rupture following anterior cruciate ligament (ACL) reconstruction. This study aimed to identify the rate of revision and surgeon-reported graft rupture and clarify the patient risk factors for failure.

METHODS

Analysis was conducted on prospective data captured by the New Zealand ACL registry. All primary isolated ACL reconstructions recorded between April 2014 and December 2018 were reviewed to identify the rate of revision and surgeon-reported graft rupture. Univariate and multivariate survival analysis was performed to identify patient factors associated with revision and graft rupture.

RESULTS

A total of 7402 primary isolated ACL reconstructions were reviewed and had a mean follow-up time of 23.1 (SD ± 13.9) months. There were 258 surgeon-reported graft ruptures (3.5%) of which 175 patients underwent subsequent revision ACL reconstruction (2.4%). Patients younger than 18 years had the highest risk of revision (adjusted HR = 7.29, p < 0.001) and graft rupture (adjusted HR = 4.26, p < 0.001) when compared to patients aged over 36 years. Male patients had a higher risk of revision (adjusted HR = 2.00, p < 0.001) and graft rupture (adjusted HR = 1.70, p < 0.001) when compared to their female counterparts. Patients who underwent ACL reconstruction within 6 months of their injury had a two times increased risk of revision compared to patients who had surgery after 12 months (adjusted HR = 2.15, p = 0.016).

CONCLUSION

Younger age, male sex and a shorter injury-to-surgery time interval increased the risk of revision, while younger age and male sex increased the risk of surgeon-reported graft rupture.

LEVEL OF EVIDENCE

II.