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

Lack of association between revision ACL reconstruction and preoperative, intraoperative and post-operative factors at primary ACL reconstruction in children and adolescents

PURPOSE

To evaluate factors associated with revision anterior cruciate ligament reconstruction (ACLR) within 5 years of primary ACLR in children and adolescents.

METHODS

Children and adolescents (age <20 years at surgery) who underwent primary hamstring tendon ACLR at the Capio Artro Clinic, Stockholm, Sweden, between January 2005 and December 2018 were identified. Revision ACLR within 5 years of primary ACLR was captured in the Swedish National Knee Ligament Registry. Univariable and multivariable logistic regression analyses were used to evaluate the associations between revision ACLR and preoperative (age, sex, body mass index, time from injury to surgery, pre-injury Tegner activity level, medial collateral ligament injury, passive contralateral knee hyperextension [≤-5°]), intraoperative (medial meniscus and lateral meniscus [LM] resection or repair, cartilage injury and graft diameter) and post-operative (KT-1000 side-to-side anterior knee laxity, limb symmetry index for extension and flexion strength and single-leg-hop (SLH) test performance at 6 months) factors at primary ACLR.

RESULTS

A total of 1888 patients (mean age: 16.0 ± 2.0, range: 8-19 years) who underwent primary ACLR were included. The overall incidence of revision ACLR within 5 years was 9.0% (170 out of 1888). Univariable analysis revealed that a time from injury to primary ACLR of <5 months (odds ratio [OR]: 2.27, 95% confidence interval [CI]: 1.61-2.35, p < 0.001) and LM resection (OR: 1.49, 95% CI: 1.00-2.20, p = 0.04) increased the odds of revision ACLR. Multivariable analysis showed that revision ACLR was significantly associated only with a time from injury to primary ACLR of <5 months (OR: 2.56, 95% CI: 1.72-3.70, p < 0.001).

CONCLUSION

There was a lack of association between revision ACLR and preoperative, intraoperative and post-operative factors at primary ACLR in children and adolescents. A time from injury to primary ACLR of <5 months was the only factor associated with revision ACLR within 5 years.

LEVEL OF EVIDENCE

Level III.

Revision Anterior Cruciate Ligament Reconstruction in Pediatric and Adolescent Patients Yields Low Rates of Graft Failure and Good Functional Scores, but Low Rates of Return to Sport: A Systematic Review

PURPOSE

To evaluate outcomes after revision anterior cruciate ligament reconstruction (ACLR) in pediatric and adolescent patients in terms of graft failure rate and functional patient outcomes.

METHODS

A systematic review of Cochrane, Embase, Scopus, Ovid, and PubMed databases was performed for all original clinical studies that reported outcomes of pediatric and adolescent patients undergoing revision ACLR. Non-English studies and studies not reporting both graft failure rates and an additional outcome measure were excluded. We evaluated patient demographics, injury mechanisms, surgical technique characteristics, concomitant injuries, failure rates, patient-reported outcome measures (PROMs), complications, and return to sports rates. Risk of bias (ROB) was assessed with the methodological index for nonrandomized studies (MINORS).

RESULTS

Five studies with a total of 239 knees in 234 patients were included. Failure of the revision ACLR ranged from 9% to 21%. Return to previous level of activity ranged between 27% and 68%. PROMs were variable, with good Lysholm Knee Scoring Scale score (range 84.5-93.7), moderate Tegner Activity Score (range 5.5-9.0), and good International Knee Documentation Committee knee scores (range 79.9-80.0). Allograft was used in 48% of revisions, followed by bone patellar tendon bone autograft in 34%, and hamstrings (HS) autograft in 14%. Meniscus injury and cartilage injury was present in 53.1% to 92.5% and 5.5% to 59.4% of knees, respectively. Gwet's AC1 coefficient was 0.89, indicating a high degree of interrater reliability. The average MINORS score was 6, and heterogeneity was low (I2 = 9%). The included studies did not present with sufficient detail to disaggregate clinical outcomes by patient sex.

CONCLUSIONS

Revision ACLR yields a graft failure ranging from 9 to 20%. Revision patients experience good PROMs but low rates of return to preinjury level of sport. Further, revision ACLR was associated with high rates of intra-articular damage and relatively low rates of meniscal repair at the time of second surgery.

LEVEL OF EVIDENCE

Level IV, systematic review of level IV evidence.

Only 10% of Patients With a Concomitant MCL Injury Return to Their Preinjury Level of Sport 1 Year After ACL Reconstruction: A Matched Comparison With Isolated ACL Reconstruction

BACKGROUND

There is a need for an increased understanding of the way a concomitant medial collateral ligament (MCL) injury may influence outcome after anterior cruciate ligament (ACL) reconstruction.

HYPOTHESIS

Patients with a concomitant MCL injury would have inferior clinical outcomes compared with a matched cohort of patients undergoing ACL reconstruction without an MCL injury.

STUDY DESIGN

Matched registry-based cohort study; case-control.

LEVEL OF EVIDENCE

Level 3.

METHODS

Data from the Swedish National Knee Ligament Registry and a local rehabilitation outcome registry were utilized. Patients who had undergone a primary ACL reconstruction with a concomitant nonsurgically treated MCL injury (ACL + MCL group) were matched with patients who had undergone an ACL reconstruction without an MCL injury (ACL group), in a 1:3 ratio. The primary outcome was return to knee-strenuous sport, defined as a Tegner activity scale ≥6, at the 1-year follow-up. In addition, return to preinjury level of sport, muscle function tests, and patient-reported outcomes (PROs) were compared between the groups.

RESULTS

The ACL + MCL group comprised 30 patients, matched with 90 patients in the ACL group. At the 1-year follow-up, 14 patients (46.7%) in the ACL + MCL group had return to sport (RTS) compared with 44 patients (48.9%) in the ACL group (P = 0.37). A significantly lower proportion of patients in the ACL + MCL group had returned to their preinjury level of sport compared with the ACL group (10.0% compared with 25.6%, adjusted P = 0.01). No differences were found between the groups across a battery of strength and hop tests or in any of the assessed PROs. The ACL + MCL group reported a mean 1-year ACL-RSI after injury of 59.4 (SD 21.6), whereas the ACL group reported 57.9 (SD 19.4), P = 0.60.

CONCLUSION

Patients with a concomitant nonsurgically treated MCL injury did not return to their preinjury level of sport to the same extent as patients without an MCL injury 1 year after ACL reconstruction. However, there was no difference between the groups in terms of return to knee strenuous activity, muscle function, or PROs.

CLINICAL RELEVANCE

Patients with a concomitant nonsurgically treated MCL injury may reach outcomes similar to those of patients without an MCL injury 1 year after an ACL reconstruction. However, few patients return to their preinjury level of sport at 1 year.

Early- and Late-Stage Benefits of Blood Flow Restriction Training on Knee Strength in Adolescents After Anterior Cruciate Ligament Reconstruction

Background

Blood flow restriction training (BFRT) after anterior cruciate ligament reconstruction (ACLR) is rising in popularity because of its benefits in reducing muscle atrophy and mitigating knee strength deficits.

Purpose

To investigate the impact BFRT has on adolescent knee strength after ACLR at 2 postoperative time points: at 3 months and the time of return to sport (RTS).

Study Design

Cohort study; Level of evidence, 3.

Methods

A prospective intervention (BFRT) group was compared to an age-, sex-, and body mass index-matched retrospective control group. Patients aged 12 to 18 years who underwent primary ACLR with a quadriceps tendon autograft were included. Along with a traditional rehabilitation protocol, the BFRT group completed a standardized BFRT protocol (3 BFRT exercises performed twice weekly for the initial 12 weeks postoperatively). Peak torque values for isometric knee extension and flexion strength (at 3 months and RTS) and isokinetic strength at 180 deg/s (at RTS) as well as Pediatric International Knee Documentation Committee (Pedi-IKDC) scores were collected. Differences between the BFRT and control groups were compared with 2-way mixed analysis of variance and 1-way analysis of variance.

Results

The BFRT group consisted of 16 patients (10 female; mean age, 14.84 ± 1.6 years) who were matched to 16 patients in the control group (10 female; mean age, 15.35 ± 1.3 years). Regardless of the time point, the BFRT group demonstrated significantly higher isometric knee extension torque compared to the control group (2.15 ± 0.12 N·m/kg [95% CI, 1.90-2.39] vs 1.74 ± 0.12 N·m/kg [95% CI, 1.49-1.98], respectively; mean difference, 0.403 N·m/kg; P = .024). The BFRT group also reported significantly better Pedi-IKDC scores compared to the control group at both 3 months (68.91 ± 9.68 vs 66.39 ± 12.18, respectively) and RTS (89.42 ± 7.94 vs 72.79 ± 22.81, respectively) (P = .047).

Conclusion

In adolescents, the addition of a standardized BFRT protocol to a traditional rehabilitation protocol after ACLR significantly improved knee strength and patient-reported function compared to a traditional rehabilitation program alone.

Machine learning can accurately predict risk factors for all-cause reoperation after ACLR: creating a clinical tool to improve patient counseling and outcomes

PURPOSE

Identifying predictive factors for all-cause reoperation after anterior cruciate ligament reconstruction could inform clinical decision making and improve risk mitigation. The primary purposes of this study are to (1) determine the incidence of all-cause reoperation after anterior cruciate ligament reconstruction, (2) identify predictors of reoperation after anterior cruciate ligament reconstruction using machine learning methodology, and (3) compare the predictive capacity of the machine learning methods to that of traditional logistic regression.

METHODS

A longitudinal geographical database was utilized to identify patients with a diagnosis of new anterior cruciate ligament injury. Eight machine learning models were appraised on their ability to predict all-cause reoperation after anterior cruciate ligament reconstruction. Model performance was evaluated via area under the receiver operating characteristics curve. To explore modeling interpretability and radiomic feature influence on the predictions, we utilized a game-theory-based method through SHapley Additive exPlanations.

RESULTS

A total of 1400 patients underwent anterior cruciate ligament reconstruction with a mean postoperative follow-up of 9 years. Two-hundred and eighteen (16%) patients experienced a reoperation after anterior cruciate ligament reconstruction, of which 6% of these were revision ACL reconstruction. SHapley Additive exPlanations plots identified the following risk factors as predictive for all-cause reoperation: diagnosis of systemic inflammatory disease, distal tear location, concomitant medial collateral ligament repair, higher visual analog scale pain score prior to surgery, hamstring autograft, tibial fixation via radial expansion device, younger age at initial injury, and concomitant meniscal repair. Pertinent negatives, when compared to previous studies, included sex and timing of surgery. XGBoost was the best-performing model (area under the receiver operating characteristics curve of 0.77) and outperformed logistic regression in this regard.

CONCLUSIONS

All-cause reoperation after anterior cruciate ligament reconstruction occurred at a rate of 16%. Machine learning models outperformed traditional statistics and identified diagnosis of systemic inflammatory disease, distal tear location, concomitant medial collateral ligament repair, higher visual analog scale pain score prior to surgery, hamstring autograft, tibial fixation via radial expansion device, younger age at initial injury, and concomitant meniscal repair as predictive risk factors for reoperation. Pertinent negatives, when compared to previous studies, included sex and timing of surgery. These models will allow surgeons to tabulate individualized risk for future reoperation for patients undergoing anterior cruciate ligament reconstruction.

LEVEL OF EVIDENCE

III.

Risk Factors for Revision or Rerupture After Anterior Cruciate Ligament Reconstruction: A Systematic Review and Meta-analysis

BACKGROUND

The rerupture or need for revision after anterior cruciate ligament reconstruction (ACLR) is a serious complication. Preventive strategies that target the early identification of risk factors are important to reduce the incidence of additional surgery.

PURPOSE

To perform a systematic review and meta-analysis to investigate risk factors for revision or rerupture after ACLR.

STUDY DESIGN

Systematic review and meta-analysis; Level of evidence, 4.

METHODS

Literature searches were performed in PubMed, Embase, and Web of Science from database inception to November 2021 and updated in January 2022. Quantitative, original studies reporting potential adjusted risk factors were included. Odds ratios (ORs) were calculated for potential risk factors.

RESULTS

A total of 71 studies across 13 countries with a total sample size of 629,120 met the inclusion criteria. Fifteen factors were associated with an increase in the risk of revision or rerupture after ACLR: male sex (OR, 1.27; 95% CI, 1.14-1.41), younger age (OR, 1.07; 95% CI, 1.05-1.08), lower body mass index (BMI) (OR, 1.03; 95% CI, 1.00-1.06), family history (OR, 2.47; 95% CI, 1.50-4.08), White race (OR, 1.32; 95% CI, 1.08-1.60), higher posterolateral tibial slope (OR, 1.15; 95% CI, 1.05-1.26), preoperative high-grade anterior knee laxity (OR, 2.30; 95% CI, 1.46-3.64), higher baseline Marx activity level (OR, 1.07; 95% CI, 1.02-1.13), return to a high activity level/sport (OR, 2.03; 95% CI, 1.15-3.57), an ACLR within less than a year after injury (OR, 2.05; 95% CI, 1.81-2.32), a concomitant medial collateral ligament (MCL) injury (OR, 1.62; 95% CI, 1.31-2.00), an anteromedial portal or transportal technique (OR, 1.36; 95% CI, 1.22-1.51), hamstring tendon (HT) autografts (vs bone-patellar tendon-bone [BPTB] autografts) (OR, 1.60; 95% CI, 1.40-1.82), allografts (OR, 2.63; 95% CI, 1.65-4.19), and smaller graft diameter (OR, 1.21; 95% CI, 1.05-1.38). The other factors failed to show an association with an increased risk of revision or rerupture after ACLR.

CONCLUSION

Male sex, younger age, lower BMI, family history, White race, higher posterolateral tibial slope, preoperative high-grade anterior knee laxity, higher baseline Marx activity level, return to a high activity level/sport, an ACLR within less than a year from injury, a concomitant MCL injury, an anteromedial portal or transportal technique, HT autografts (vs BPTB autografts), allografts, and smaller graft diameter may increase the risk of revision or rerupture after ACLR. Raising awareness and implementing effective preventions/interventions for risk factors are priorities for clinical practitioners to reduce the incidence of revision or rerupture after ACLR.

Reliability of MRI Detection of Kaplan Fiber Injury in Pediatric and Adolescent Patients with ACL Tears

Background:

While studies have described Kaplan fiber (KF) injury in up to 60% of adults with anterior cruciate ligament (ACL) tears, the incidence of KF injury in the pediatric and adolescent population remains unknown.

Purpose:

To (1) determine the reliability of using magnetic resonance imaging (MRI) to identify KF injury in the pediatric and adolescent population and (2) define the incidence of KF injury in these patients with acute ACL injuries.

Study Design:

Cohort study (diagnosis); Level of evidence, 3.

Methods:

The authors retrospectively identified patients ≤18 years of age who underwent ACL reconstruction for acute tears between 2013 and 2020. All preoperative MRI scans were reviewed independently and in a blinded fashion by 2 musculoskeletal radiologists, who noted the presence of the KF complex and any evidence of injury; interrater reliability was assessed. Patient characteristics, time from injury to MRI, laterality, and concomitant ligamentous or meniscal injuries were recorded, and associations between patient or injury characteristics and KF integrity on MRI were assessed.

Results:

In total, 51 patients (mean age, 14.9 years) met the inclusion criteria. Of these, 27 patients were female and 31 sustained an injury to the right knee. With respect to KF integrity, radiologist 1 visualized KF injury in 29% of patients, while radiologist 2 visualized KF injury in 35% of patients. In 12% of cases for radiologist 1 and 6% of cases for radiologist 2, KFs were unable to be visualized at all. The overall percentage agreement between the 2 radiologists was 76.5% with a kappa statistic of 0.57 (moderate agreement). There were no significant associations found between the presence of KF injury and patient age, sex, laterality, body mass index, concomitant ligamentous injury, or meniscal injury. However, visualization of KF injury on MRI was associated with a shorter time from index injury to MRI (15 days vs 23 days; P = .044).

Conclusion:

Approximately one-third of pediatric and adolescent patients who underwent ACL reconstruction were found to have KF injuries. Standard preoperative MRI scans can reliably be used to visualize KF injury in the majority of pediatric and adolescent patients with ACL tears, especially when the MRI is performed in the acute setting.

Combining Anterior Cruciate Ligament Reconstruction With Lateral Extra-Articular Procedures in Skeletally Immature Patients Is Safe and Associated With a Low Failure Rate

Purpose

To analyze the rates of graft ruptures and growth disorders, the level of return to sport, and the clinical results of 2 lateral extra-articular procedures in growing children.

Methods

This study was a retrospective, single-center study of patients undergoing anterior cruciate ligament (ACL) surgery combined with 2 different lateral extra-articular procedures (anatomic reconstruction with a gracilis graft or modified Lemaire technique with a strip of fascia lata). The measurements of side-to-side anterior laxity and pivot shift were performed preoperatively and at the last follow-up. The sports level and the complications rate were assessed. The minimal clinically important differences (MCID) and patient acceptable symptoms state threshold scores were calculated.

Results

Thirty-nine patients (40 ACLs) were included (20 anatomic and 20 modified Lemaire) at an average follow-up of 57 months ± 10 [42-74]. One patient (2.5%) was lost to follow-up. The mean age at surgery was 13.8 ± 1.4 years old [9.8; 16.5]. One graft failure was reported (2.6% [0.06-13.5]) at 35.6 months after surgery. Two cases (5.4%) of femoral overgrowth were observed, and one of them required distal femoral epiphysiodesis. Ninety-two percent of the patients returned to sports. At the final follow-up, side-to-side anterior laxity was significantly improved, and no residual pivot shift was recorded in 95% of patients. Eighty-nine percent of the patients presented a Pedi-International Knee Documentation Committee score greater than the MCID postoperatively, and 77% presented a Lysholm score greater than the MCID.

Conclusions

This series of ACL reconstructions combined with 2 different lateral extra-articular procedures in skeletally immature patients demonstrated promising findings. The low rate of observed complications, including graft rupture and growth disturbance, is encouraging, but the small study population and lack of comparative group precludes reliable conclusions.

Level of Evidence

IV, therapeutic case series.