No difference in revision rates between single- and double-bundle anterior cruciate ligament reconstruction: a comparative study of 16,791 patients from the Swedish national knee ligament register

Validating the capture rate of revisions by the New Zealand ACL Registry: An analysis of all-cause reoperation following primary ACL reconstruction

PURPOSE

To validate the New Zealand Anterior Cruciate Ligament (ACL) Registry's capture rate of revisions by cross-referencing Registry data with reoperations data recorded by the Accident Compensation Corporation (ACC) and identify risk factors for all-cause reoperation.

METHODS

Primary ACL reconstructions performed between April 2014 and September 2019 were individually matched on a record-by-record basis between the two databases. The ACC database was used to identify patients who underwent a reoperation with manual review of operation notes to identify whether a revision or other procedure was performed. This was combined with the number of revisions separately recorded in the New Zealand ACL Registry, which was used as the denominator value to calculate the Registry's capture rate of revisions. Patient and surgical data recorded in the Registry were analysed to identify independent predictors for all-cause reoperation.

RESULTS

A total of 8046 primary ACL reconstructions were matched between the New Zealand ACL Registry and the ACC databases. The reoperation rate was 8.9% (n = 715) at a mean follow-up of 2.5 years. Meniscal-related procedures were the most common reoperation (n = 299, 3.7%), followed by revision ACL reconstruction (n = 219, 2.7%), arthrofibrosis (n = 185, 2.3%), cartilage (n = 56, 0.7%) and implants (n = 32, 0.4%). The New Zealand ACL Registry captured 96% of revisions. Younger age (hazard ratio [HR] > 1.4, p < 0.001), earlier surgery (HR > 1.3, p = 0.05), concurrent meniscal repair (medial meniscus HR = 1.9, p < 0.001 and lateral meniscus HR = 1.3, p = 0.022) and hamstring tendon autografts (HR = 1.4, p = 0.001) were associated with a higher risk of reoperation.

CONCLUSION

The New Zealand ACL Registry captured 96% of revisions. Risk factors for all-cause reoperation included younger age, earlier surgery, meniscal repair and hamstring tendon autografts.

LEVEL OF EVIDENCE

Level III.

Differences in postoperative knee function based on concomitant treatment of lateral meniscal injury in the setting of primary ACL reconstruction

BACKGROUND

Concomitant lateral meniscal (LM) injuries are common in acute anterior cruciate ligament (ACL) ruptures. However, the effect of addressing these injuries with various treatment methods during primary ACL reconstruction (ACLR) on patient-reported outcomes (PROs) is unknown. Therefore, the purpose of this study was to compare postoperative Knee injury and Osteoarthritis Outcome Score (KOOS) at 2-, 5-, and 10-years after isolated primary ACLR to primary ACLR with various treatment methods to address concomitant LM injury.

METHODS

This study was based on data from the Swedish National Knee Ligament Registry. Patients ≥ 15 years with data on postoperative KOOS who underwent primary ACLR between the years 2005 and 2018 were included in this study. The study population was divided into five groups: 1) Isolated ACLR, 2) ACLR + LM repair, 3) ACLR + LM resection, 4) ACLR + LM injury left in situ, and 5) ACLR + LM repair + LM resection. Patients with concomitant medial meniscal or other surgically treated ligament injuries were excluded.

RESULTS

Of 31,819 included patients, 24% had LM injury. After post hoc comparisons, significantly lower scores were found for the KOOS Symptoms subscale in ACLR + LM repair group compared to isolated ACLR (76.0 vs 78.3, p = 0.0097) and ACLR + LM injury left in situ groups (76.0 vs 78.3, p = 0.041) at 2-year follow-up. However, at 10-year follow-up, no differences were found between ACLR + LM repair and isolated ACLR, but ACLR + LM resection resulted in significantly lower KOOS Symptoms scores compared to isolated ACLR (80.4 vs 82.3, p = 0.041).

CONCLUSION

The results of this study suggest that LM injury during ACLR is associated with lower KOOS scores, particularly in the Symptoms subscale, at short- and long-term follow-up. However, this finding falls below minimal clinical important difference and therefore may not be clinically relevant.

LEVEL OF EVIDENCE

III.

Double-Versus Single-Bundle Anterior Cruciate Ligament Reconstructive Surgery: A Prospective Study With >1 Year Follow-Up

Background The increased prevalence of knee trauma predominantly adds to the anterior cruciate ligament (ACL) tear frequencies that require single- or double-bundle reconstructive surgeries. Few studies have demonstrated the superior results of double-bundle reconstruction compared to single-bundle approaches. This study investigated the knee function improvement capacity of both reconstruction techniques in patients with ACL tears. Methods Thirty cases with ACL tears have been enrolled and segregated equally in distinct (single-bundle versus double-bundle) batches. The diagnostic assessments were undertaken through comprehensive clinical history, knee radiographs, Lysholm scoring, the International Knee Documentation Committee (IKDC) scale, the Lachman analysis, the International Knee Documentation Committee (IKDC) scale, and the pivot shift method. Results After one year, there was a significant enhancement in the postoperative versus preoperative Lysholm scores in the single-bundle (58.5 ± 21.2 vs. 82.4 ± 26.2, p<0.001) and double-bundle (86.4 ± 22.8 vs 60.3 ± 19.2, p<0.001) groups. There was a significant improvement in the IKDC scores after a follow-up period of one year (p-value: 0.012 and p-value: 0.002, respectively) in both of the study batches. After a year of follow-up, Lysholm scores (p=0.352) and IKDC scores (p=0.574) between the study groups (82.4 ± 26.2 vs. 86.4 ± 22.8) were comparable. Conclusion The clinical outcomes remained comparable between subjects with single-bundle reconstruction versus double-bundle reconstruction subjects with ACL injuries. Findings were similar between the groups after one year and two years of surgical interventions.

Substantial Loss to Follow-Up and Missing Data in National Arthroscopy Registries: A Systematic Review

PURPOSE

To report follow-up methodologies, compliance, and existing strategies for handling missing data in national arthroscopy registries collecting patient-reported outcome measures (PROMs).

METHODS

Annual reports, EMBASE, and MEDLINE were queried following the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines to identify national arthroscopy registries reporting follow-up with a validated PROM and sample size greater than 500. Extracted data included weighted compliance in peer-reviewed publications, cumulative compliance throughout the time span of data collection, and missing-data methodologies.

RESULTS

Nine national arthroscopy registries currently collect PROMs, with cumulative rates of follow-up ranging from less than 10% to more than 70%. We identified 36 publications from 5 national registries reporting hip and knee arthroscopies. The weighted mean compliance with PROMs in national registry publications was 56% at 0.5 years, 44% to 59% at 1 year, 40% to 61% at 2 years, 35% to 54% at 5 years, and 40% at 10 years. A missing-data analysis was reported or referenced in 58% of publications.

CONCLUSIONS

In national arthroscopy registries, compliance with 2-year PROMs does not meet traditional follow-up thresholds of 60% or 80% and reporting of missing-data methodologies is inconsistent.

LEVEL OF EVIDENCE

Level IV, systematic review of Level II through IV studies.

No difference in revision rates between anteromedial portal and transtibial drilling of the femoral graft tunnel in primary anterior cruciate ligament reconstruction: early results from the New Zealand ACL Registry

PURPOSE

The use of an accessory anteromedial portal to drill the femoral graft tunnel in primary anterior cruciate ligament (ACL) reconstruction was introduced in the 2000s in an effort to achieve a more anatomic femoral tunnel position. However, some early studies reported an increase in revision ACL reconstruction compared to the traditional transtibial technique. The aim of this study was to analyse recent data recorded by the New Zealand ACL Registry to compare outcomes of ACL reconstruction performed using the anteromedial portal and transtibial techniques.

METHODS

Analysis was performed on primary isolated single-bundle ACL reconstructions recorded between 2014 and 2018 by the New Zealand ACL Registry. Patients were categorised into two groups according to whether an anteromedial portal or transtibial technique was used to drill the femoral graft tunnel. The primary outcome was revision ACL reconstruction and was compared between both groups through univariate and multivariate survival analyses. The secondary outcomes that were analysed included subscales of the Knee Injury and Osteoarthritis Outcome Score (KOOS) and Marx activity score.

RESULTS

Six thousand one hundred and eighty-eight primary single-bundle ACL reconstructions were performed using either the anteromedial portal or transtibial drilling techniques. The mean time of follow-up was 23.3 (SD ± 14.0) months. Similar patient characteristics such as mean age (29 years, SD ± 11), sex (males = 58% versus 57%) and time to surgery (median 4 months, IQR 5) were observed between both groups. The rate of revision ACL reconstruction was 2.6% in the anteromedial portal group and 2.2% in the transtibial group (n.s.). The adjusted risk of revision ACL reconstruction was 1.07 (95% CI 0.62-1.84, n.s.). Patients in the anteromedial portal group reported improved scores for subscales of the KOOS and higher Marx activity scores at 1-year post-reconstruction.

CONCLUSION

There was no difference in the risk of revision ACL reconstruction between the two femoral tunnel drilling techniques at short-term follow-up. We observed minor differences in patient-reported outcomes at 1-year follow-up favouring the anteromedial portal technique, which may not be clinically relevant. Surgeons can achieve good clinical outcomes with either drilling technique.

LEVEL OF EVIDENCE

III.

Oval femoral tunnel technique is superior to the conventional round femoral tunnel technique using the hamstring tendon in anatomical anterior cruciate ligament reconstruction

PURPOSE

This study was conducted to compare the efficacy between the oval femoral tunnel technique and the conventional round femoral tunnel technique in ACL reconstruction using an autologous hamstring tendon on the basis of the postoperative clinical outcomes and ACL graft tendon maturity. The hypothesis was that ACL reconstruction performed using the oval femoral tunnel technique was better than that performed using the round femoral tunnel technique in clinical functions and graft maturity.

METHODS

One hundred and eight patients who underwent anatomical single-bundle ACL reconstruction were included in this study and the follow-up period was at least 2 years. Thirty-nine patients admitted between February and August in 2016 were included in the oval femoral tunnel group and 69 patients admitted between September 2016 and March 2017 were included in the round femoral tunnel group. The Lachman test result, pivot-shift test result, Lysholm score, IKDC score, and VAS score were used for the clinical evaluation. An objective assessment of anteroposterior stability was performed using a KT1000 arthrometer. Postoperative MRI was conducted to compare the ACL graft maturity differences between the oval femoral tunnel group and round femoral tunnel group, where the signal/noise quotient (SNQ) was calculated. In addition, second-look arthroscopy was conducted to compare the graft status and synovial coverage at 24 months postoperatively.

RESULTS

All the patients presented with significant improvement in all clinical scores from the preoperative period to the 24-month follow-up. During the postoperative follow-up period, no statistically significant differences were found between the two groups in terms of the VAS score, knee ROM, Lachman test results, and graft status determined in the second-look arthroscopic evaluation. The Lysholm score was 97.1 ± 3.9 and 94.8 ± 5.6 in the oval femoral tunnel group and round femoral tunnel group, respectively, at the 24-month follow-up (p = 0.031). The IKDC subjective score was 92.0 ± 2.6 and 89.0 ± 3.6 in the oval femoral tunnel group and round femoral tunnel group, respectively, at the end of the follow-up period (p < 0.001). Significantly more patients with 1-degree positive pivot-shift test results were observed in the round femoral tunnel group (10/65) than in the oval femoral tunnel group (1/37) at the end of the follow-up period (p = 0.048). The mean SNQ of the oval femoral tunnel group was 2.7 ± 0.9, which was significantly lower than that of the round femoral tunnel group (3.6 ± 1.1) at the 24-month postoperative follow-up (p < 0.001).

CONCLUSIONS

Based on the clinical evaluations, MRI findings and second-look arthroscopy results of the two groups, the oval femoral tunnel technique yielded significantly better knee function and knee laxity restoration and more mature ACL grafts than the round femoral tunnel technique, whereas no significant differences were found at the second-look arthroscopy.

LEVEL OF EVIDENCE

III.

Editorial Commentary: Sometimes You Don't Know What You've Got Until It's Gone-The Effect of Missing Data in "Big Data" Studies

Big-data studies are powerful tools for comparative-effectiveness research, but because of the large number of included patients, they risk falsely identifying a difference when none exists because large sample sizes may result in statistically significant differences that have little clinical importance. Other limitations of big-data studies include lack of generalizability because of inclusion of only specific patient populations, lack of validated outcome measures, recording bias or clerical error, and vast troves of missing data. As such, the methods and results of big-data studies require careful scrutiny to ensure that the conclusions are correct.

Factors associated with revision following anterior cruciate ligament reconstruction: A systematic review of registry data

BACKGROUND

To identify the patient and surgical factors associated with revision anterior cruciate ligament (ACL) reconstruction as reported by all national and community ACL registries.

METHODS

A systematic review was performed on the MEDLINE, Embase and Cochrane Library databases. Eligibility criteria included English studies published by national or community ACL registries reporting on primary ACL reconstruction and risk factors associated with revision ACL reconstruction.

RESULTS

Thirty-three studies from the Swedish, Norwegian, Danish and Kaiser Permanente registries were included for review. Fourteen studies from all four registries reported younger age as a risk factor for revision ACL reconstruction. In addition, the Swedish registry reported concomitant medial collateral ligament (MCL) injury, undergoing earlier surgery, lower Knee Injury and Osteoarthritis Outcome Score (KOOS), smaller graft diameter and an anteromedial portal drilling technique as risk factors for revision. The risk factors reported by the Norwegian registry included lower body mass index (BMI), lower KOOS, hamstring tendon grafts and suspensory fixation. The Danish registry reported hamstring tendon grafts, anteromedial portal drilling and suspensory fixation as risk factors. The Kaiser Permanente registry reported male sex, lower BMI, ethnicity, hamstring tendon grafts, allografts, smaller graft diameter and an anteromedial portal technique as risk factors for revision.

CONCLUSION

Multiple patient and surgical factors were associated with increased risk of revision ACL reconstruction in registries. Younger age and the use of hamstring tendon grafts were consistently reported as risk factors for failure.

Revision Anterior Cruciate Ligament Reconstruction After Primary Anatomic Double-Bundle Anterior Cruciate Ligament Reconstruction: A Case Series of 40 Patients

PURPOSE

To evaluate the surgical methods according to the status of tunnels at the time of revision anterior cruciate ligament reconstruction (ACLR) and to evaluate clinical outcomes of revision ACLR in patients who underwent primary ACLR with the anatomic 4-tunnel double-bundle (DB) technique.

METHODS

A total of 487 patients who underwent primary anatomic DB ACLR from April 2010 to July 2016 were retrospectively reviewed, and among those knees, the patients who underwent revision ACLR were included in the study. The patients with concomitant posterior cruciate ligament injuries were excluded. Forty patients (40 knees) were identified and enrolled. The surgical methods were reviewed. The range of motion, objective laxity using KT-2000, Lysholm score, Hospital for Special Surgery score, International Knee Documentation Committee subjective score, and Tegner score after revision ACLR were compared with those after primary ACLR in the same patient using paired t-test with Bonferroni correction.

RESULTS

The timing of reinjury after primary ACLR and mean interval between primary and revision ACLR were 18 months (range 1.5-80 months) and 24 months (range 4-82 months), respectively. Among 40 patients, 38 patients (95%) underwent 1-stage revision with the DB technique using pre-existing tunnels without compromised positioning of the grafts, and the other 2 patients (5%) underwent 2-stage revision. The postrevision range of motion, KT-2000, Lysholm score, Hospital for Special Surgery score, International Knee Documentation Committee subjective score, and Tegner score were 137 ± 7°, 2.4 ± 1.2 mm, 91.4 ± 5.8, 98.9 ± 2.2, 78.6 ± 11.5, and 5.5 ± 1.2, respectively, and did not show any differences from those after primary ACLR.

CONCLUSIONS

In the revision setting after primary anatomic DB ACLR, most of the cases could be managed with 1-stage revision with DB technique using pre-existing tunnels, and the objective laxity and clinical scores after revision DB ACLR were comparable with those after primary DB ACLR.

LEVEL OF EVIDENCE

Case series, Level IV.

Strength in numbers? The fragility index of studies from the Scandinavian knee ligament registries

PURPOSE

The fragility index (FI) is a metric to evaluate the robustness of statistically significant results. It describes the number of patients who would need to change from a non-event to an event to change a result from significant to non-significant. This systematic survey aimed to evaluate the feasibility of applying the FI to findings related to anterior cruciate ligament (ACL) reconstruction in the Scandinavian knee ligament registries.

METHODS

The PubMed, EMBASE, Cochrane Library and AMED databases were searched. Studies from the Scandinavian knee ligament registers were eligible if they reported a statistically significant result (p < 0.05) for any of the following dichotomous outcomes; ACL revision, contralateral ACL reconstruction or the presence of postoperative knee laxity. Only studies with a two-arm comparative analysis were included. Eligibility assessment, data extraction and quality assessment were performed by two independent reviewers. The dichotomous analyses were stratified according to the grouping variable for the two comparative arms as follows; age, patient sex, activity at injury, graft choice, drilling technique, graft fixation, single- versus double-bundle, concomitant cartilage injury and country. The two-sided Fisher's exact test was used to calculate the FI of all statistically significant analyses.

RESULTS

From 158 identified studies, 13 studies were included. They reported statistical significance for a total of 56 dichotomous analyses, of which all but two had been determined by a time-to-event analysis. The median sample size for the arms was 5540 (range 92-38,666). The mean FI for all 56 dichotomous analyses was 80.6 (median 34.5), which means that a mean of 80.6 patients were needed to change outcome status to generate a non-significant result instead of a significant one. Seventeen analyses (30.4%) immediately became non-significant when performing the two-sided Fisher's exact test and, therefore, had an FI of 0. The analyses related to age were the most robust, with a mean FI of 178.5 (median 116, range 1-1089). The mean FI of the other grouping variables ranged from 0.5 to 48.0.

CONCLUSION

There was large variability in the FI in analyses from the Scandinavian knee ligament registries and almost one third of the analyses had an FI of zero. The FI is a rough measurement of robustness when applied to registry studies, however, future studies are needed to determine the most appropriate metric for robustness in registry studies. The use of the FI can provide clinicians with a deeper understanding of significant study results and promotes an evidence-based approach in the clinical care of patients.

LEVEL OF EVIDENCE

Systematic review of prospective cohort studies, Level II.

Functional double-bundle anterior cruciate ligament reconstruction using hamstring tendon autografts with preserved insertions is an effective treatment for tibiofemoral instability

PURPOSE

The aim of this study was to introduce a modified anatomical anterior cruciate ligament reconstruction using functional double bundles (F-DBACLR), which achieved sequential tensioning at all flexion angles postoperatively, and compare its clinical outcomes with the anatomical single-bundle technique (A-SBACLR).

METHODS

A total of 156 patients with an ACL injury underwent ACLR (A-SB group, n = 78; F-DB group, n = 78). All operations were performed by anatomically identifying the ACL footprints and fixing the graft at a pre-determined degree of knee flexion. Two observers blinded to the patient identities examined the patients preoperatively and during follow-up (median 28.2 months; range 26-31 months). Multiple subjective and objective clinical evaluation tests and assessment of clinical outcomes concerning the translational and rotational stability of the knee including the International Knee Documentation Committee (IKDC) questionnaire, Lysholm Knee Scoring Scale, Knee Injury and Osteoarthritis Outcome Score (KOOS), Tegner Activity Scale, KT-1000 laxity measurements, Lachman test and pivot-shift test were performed preoperatively and postoperatively.

RESULTS

Preoperatively, no differences were found between the two groups. During the 2-year observation period, patients in the F-DB group revealed better clinical outcomes in terms of the Tegner Activity Scale Score, IKDC, KOOS and Lysholm Knee Scoring Scale. Similar results were shown in regard to the translational stability in both groups, while the F-DB group had more rotational stability at 2 years of follow-up.

CONCLUSIONS

The clinical outcomes indicated that F-DBACLR is clinically practicable and advantageous in the treatment of the ACL-deficient knee.

LEVEL OF EVIDENCE

II.

Factors that affect patient reported outcome after anterior cruciate ligament reconstruction-a systematic review of the Scandinavian knee ligament registers

OBJECTIVE

To perform a systematic review of findings from the Scandinavian knee ligament registers with regard to factors that affect patient reported outcome after anterior cruciate ligament (ACL) reconstruction.

DESIGN

Systematic review.

DATA SOURCES

Four electronic databases: PubMed, EMBASE, the Cochrane Library and AMED were searched, and 157 studies were identified. Two reviewers independently screened the titles, abstracts and full text articles for eligibility. A modified version of the Downs and Black checklist was applied for quality appraisal.

ELIGIBILITY CRITERIA FOR SELECTING STUDIES

Studies published from the Scandinavian registers from their establishment in 2004 and onwards that documented patient reported outcome and provided information on concomitant injuries were eligible.

RESULTS

A total of 35 studies were included. Younger age at ACL reconstruction, male sex, not smoking and receiving a hamstring tendon autograft positively influenced patient reported outcome. Patients with concomitant cartilage and meniscal injuries reported inferior subjective knee function compared with patients with an isolated ACL tear. One study reported that patients treated non-reconstructively reported inferior knee function compared with patients who had ACL reconstruction.

CONCLUSION

Younger age, male sex, not smoking, receiving a hamstring tendon autograft and the absence of concomitant injuries were associated with superior patient reported outcomes after ACL reconstruction.

Factors associated with additional anterior cruciate ligament reconstruction and register comparison: a systematic review on the Scandinavian knee ligament registers

Objective

To present an overview of the Scandinavian knee ligament registers with regard to factors associated with additional ACL reconstruction, and studies comparing the Scandinavian registers with other knee ligament registers.

Design

Systematic review.

Data sources

Four electronic databases: PubMed, EMBASE, the Cochrane Library and AMED were searched, and 157 studies were identified. Two reviewers independently screened titles, abstracts and full-text studies for eligibility. A modified version of the Downs and Black checklist was applied for quality appraisal.

Eligibility criteria for selecting studies

Eligible studies were those published since the establishment of the Scandinavian registers in 2004, which reported factors associated with additional ACL reconstruction and compared data from other registers.

Results

Thirty-one studies met the inclusion criteria and generally displayed good reporting quality. Adolescent age (<20 years) was the most common factor associated with additional ACL reconstruction. The choice of hamstring tendon graft compared with patella tendon, transportal femoral tunnel drilling, smaller graft diameter and utilisation of suspensory fixation devices were associated with additional ACL reconstruction. Concomitant cartilage injury decreased the likelihood of additional ACL reconstruction. Patient sex alone did not influence the likelihood. The demographics of patients undergoing ACL reconstruction in the Scandinavian registers are comparable to registers in other geographical settings. However, there are differences in surgical factors including the presence of intra-articular pathology and graft choice.

Summary

The studies published from the Scandinavian registers in general have a high reporting quality when regarded as cohort studies. Several factors are associated with undergoing additional ACL reconstruction. The results from the registers may help facilitate treatment decisions.

Patient demographic and surgical characteristics in anterior cruciate ligament reconstruction: a description of registries from six countries

OBJECTIVE

Findings from individual anterior cruciate ligament reconstruction (ACLR) registry studies are impactful, but how various registries from different countries compare with different patient populations and surgical techniques has not been described. We sought to describe six ACLR registry cohorts to understand variation across countries.

METHODS

Five European registries and one US registry participated. For each registry, all primary ACLR registered between registry establishment through 31December 2014 were identified. Descriptive statistics included frequencies, proportions, medians and IQRs. Revision incidence rates following primary ACLR were computed.

RESULTS

101 125 ACLR were included: 21 820 in Denmark, 300 in Luxembourg, 17 556 in Norway, 30 422 in Sweden, 2972 in the UK and 28 055 in the US. In all six cohorts, males (range: 56.8%-72.4%) and soccer injuries (range: 14.1%-42.3%) were most common. European countries mostly used autografts (range: 93.7%-99.7%); allograft was most common in the US (39.9%). Interference screw was the most frequent femoral fixation in Luxembourg and the US (84.8% and 42.9%), and suspensory fixation was more frequent in the other countries (range: 43.9%-75.5%). Interference was the most frequent tibial fixation type in all six cohorts (range: 64.8%-98.2%). Three-year cumulative revision probabilities ranged from 2.8% to 3.7%.

CONCLUSIONS

Similarities in patient demographics and injury activity were observed between all cohorts of ACLR. However, graft and fixation choices differed. Revision rates were low. This work, including >100 000 ACLR, is the most comprehensive international description of contemporary practice to date.

Big Data: Progress or a Big Headache?

Large administrative database, or "big data" research studies can include an immense number of patients. Strengths of research based on big data include generalizability resulting from diverse patients, diverse providers, and diverse clinical settings. Limitations of research based on large administrative databases may include indeterminate quality and obscure purpose of data entry, lack of information regarding confounding variables, and suboptimal clinical outcome measures. Thus, research conclusions based on big data must be scrutinized in a discerning and critical manner.

Reinterventions after dynamic intraligamentary stabilization in primary anterior cruciate ligament repair

BACKGROUND

The goal of this study was to perform an in-depth analysis of the frequency and cause of secondary interventions subsequent to primary anterior cruciate ligament (ACL) repair with dynamic intraligamentary stabilization (DIS).

METHODS

Between July 2009 and June 2014, 455 patients underwent DIS treatment. The minimum follow-up was 21months (mean 28months, range 21-64months).

RESULTS

A total of 215 (48.2%) reinterventions were performed in 190 (42.6%) patients. One-hundred and seventy-six (39.4%) were non-revision reinterventions, and 39 (8.7%) were revision ACL reconstructions. Re-arthroscopies included 26 (5.8%) scar tissue debridements with hardware removal due to range of motion deficits, 14 (3.1%) partial meniscectomies, four (0.9%) meniscal sutures, and four (0.9%) arthroscopies due to crepitation or knee pain. Minor non-revision reinterventions performed under analgosedation consisted of 97 (21.7%) hardware removals, 20 (4.5%) hardware removals with manipulations under anesthesia, and four manipulations under anesthesia alone (0.9%).

CONCLUSIONS

In our study, the revision rate was within the range of published results after ACL reconstructions. In over 90% of patients, the native ACL was preserved with no need for a secondary reconstruction. Most of the non-revision reinterventions were minor and included hardware removals and manipulations under anesthesia. The re-arthroscopy rate was lower than that after ACL reconstruction with fewer secondary meniscal sutures and partial meniscectomies. Early treatment of meniscal tears may be one crucial benefit of ACL repair with DIS.

Similar cost-utility for double- and single-bundle techniques in ACL reconstruction

PURPOSE

The aim was to estimate the cost-utility of the DB technique (n = 53) compared with the SB (n = 50) technique 2 years after ACL reconstruction.

METHODS

One hundred and five patients with an ACL injury were randomised to either the Double-bundle (DB) or the Single-bundle (SB) technique. One hundred and three patients (SBG n = 50, DBG n = 53) attended the 2-year follow-up examination. The mean age was 27.5 (8.4) years in the SBG and 30.1 (9.1) years in the DBG. The cost per quality-adjusted life years (QALYs) was used as the primary outcome. Direct costs were the cost of health care, in this case outpatient procedures. Indirect costs are costs related to reduce work ability for health reasons. The cost-utility analysis was measured in terms of QALY gained.

RESULTS

The groups were comparable in terms of clinical outcome. Operating room time was statistically significantly longer in the DBG (p = 0.001), making the direct costs statistically significantly higher in the DBG (p = 0.005). There was no significant difference in QALYs between groups. In the cost-effectiveness plane, the mean difference in costs and QALYs from the trial data using 1000 bootstrap replicates in order to visualise the uncertainty associated with the mean incremental cost-effectiveness ratio (ICER) estimate showed that the ICERs were spread out over all quadrants. The cost-effectiveness acceptability curve showed that there was a 50% probability of the DB being cost-effective at a threshold of Euro 50,000.

CONCLUSION

The principal findings are that the DB is more expensive from a health-care perspective. This suggests that the physician may choose individualised treatment to match the patients' expectations and requirements.

Risk of Revision Was Not Reduced by a Double-bundle ACL Reconstruction Technique: Results From the Scandinavian Registers

BACKGROUND

Double-bundle anterior cruciate ligament (ACL) reconstruction has demonstrated improved biomechanical properties and moderately better objective outcomes compared with single-bundle reconstructions. This could make an impact on the rerupture rate and reduce the risk of revisions in patients undergoing double-bundle ACL reconstruction compared with patients reconstructed with a traditional single-bundle technique. The National Knee Ligament Registers in Scandinavia provide information that can be used to evaluate the revision outcome after ACL reconstructions.

QUESTIONS/PURPOSES

The purposes of the study were (1) to compare the risk of revision between double-bundle and single-bundle reconstructions, reconstructed with autologous hamstring tendon grafts; (2) to compare the risk of revision between double-bundle hamstring tendon and single-bundle bone-patellar tendon-bone autografts; and (3) to compare the hazard ratios for the same two research questions after Cox regression analysis was performed.

METHODS

Data collection of primary ACL reconstructions from the National Knee Ligament Registers in Denmark, Norway, and Sweden from July 1, 2005, to December 31, 2014, was retrospectively analyzed. A total of 60,775 patients were included in the study; 994 patients were reconstructed with double-bundle hamstring tendon grafts, 51,991 with single-bundle hamstring tendon grafts, and 7790 with single-bundle bone-patellar tendon-bone grafts. The double-bundle ACL-reconstructed patients were compared with the two other groups. The risk of revision for each research question was detected by the risk ratio, hazard ratio, and the corresponding 95% confidence intervals. Kaplan-Meier analysis was used to estimate survival at 1, 2, and 5 years for the three different groups. Furthermore, a Cox proportional hazard regression model was applied and the hazard ratios were adjusted for country, age, sex, meniscal or chondral injury, and utilized fixation devices on the femoral and tibial sides.

RESULTS

There were no differences in the crude risk of revision between the patients undergoing the double-bundle technique and the two other groups. A total of 3.7% patients were revised in the double-bundle group (37 of 994 patients) versus 3.8% in the single-bundle hamstring tendon group (1952 of 51,991; risk ratio, 1.01; 95% confidence interval (CI), 0.73-1.39; p = 0.96), and 2.8% of the patients were revised in the bone-patellar tendon-bone group (219 of the 7790 bone-patellar tendon-bone patients; risk ratio, 0.76; 95% CI, 0.54-1.06; p = 0.11). Cox regression analysis with adjustment for country, age, sex, menisci or cartilage injury, and utilized fixation device on the femoral and tibial sides, did not reveal any further difference in the risk of revision between the single-bundle hamstring tendon and double-bundle hamstring tendon groups (hazard ratio, 1.18; 95% CI, 0.85-1.62; p = 0.33), but the adjusted hazard ratio showed a lower risk of revision in the single-bundle bone-patellar tendon-bone group compared with the double-bundle group (hazard ratio, 0.62; 95% CI, 0.43-0.90; p = 0.01). Comparisons of the graft revision rates reported separately for each country revealed that double-bundle hamstring tendon reconstructions in Sweden had a lower hazard ratio compared with the single-bundle hamstring tendon reconstructions (hazard ratio, 1.00 versus 1.89; 95% CI, 1.09-3.29; p = 0.02). Survival at 5 years after index surgery was 96.0% for the double-bundle group, 95.4% for the single-bundle hamstring tendon group, and 97.0% for the single-bundle bone-patellar tendon-bone group.

CONCLUSIONS

Based on the data from all three national registers, the risk of revision was not influenced by the reconstruction technique in terms of using single- or double-bundle hamstring tendons, although national differences in survival existed. Using bone-patellar tendon-bone grafts lowered the risk of revision compared with double-bundle hamstring tendon grafts. These findings should be considered when deciding what reconstruction technique to use in ACL-deficient knees. Future studies identifying the reasons for graft rerupture in single- and double-bundle reconstructions would be of interest to understand the findings of the present study.

LEVEL OF EVIDENCE

Level III, therapeutic study.

Equivalent Knee Injury and Osteoarthritis Outcome Scores 12 and 24 Months After Anterior Cruciate Ligament Reconstruction: Results From the Swedish National Knee Ligament Register

BACKGROUND

It is not clear whether Knee injury and Osteoarthritis Outcome Score (KOOS) results will be different 1 or 2 years after anterior cruciate ligament (ACL) reconstruction.

PURPOSE

To investigate within individual patients enrolled in the Swedish National Knee Ligament Register whether there is equivalence between KOOS at 1 and 2 years after primary ACL reconstruction.

STUDY DESIGN

Cohort study; Level of evidence, 2.

METHODS

This cohort study was based on data from the Swedish National Knee Ligament Register during the period January 1, 2005, through December 31, 2013. The longitudinal KOOS values for each individual at the 1- and 2-year follow-up evaluations were assessed through the two one-sided test (TOST) procedure with an acceptance criterion of 4. Subset analysis was performed with patients classified by sex, age, graft type, and type of injury (meniscal and/or cartilage injury).

RESULTS

A total of 23,952 patients were eligible for analysis after exclusion criteria were applied (10,116 women, 42.2%; 13,836 men, 57.8%). The largest age group was between 16 and 20 years of age (n = 6599; 27.6%). The most common ACL graft was hamstring tendon (n = 22,504; 94.0%), of which the combination of semitendinosus and gracilis was the most common. A total of 7119 patients reported on the KOOS Pain domain at both 1- and 2-year follow-ups, with a mean difference of 0.21 (13.1 SD, 0.16 SE [90% CI, -0.05 to 0.46], P < .001). The same results were found for the other KOOS subscales: symptoms (mean difference -0.54, 14.1 SD, 0.17 SE [90% CI, -0.81 to -0.26], P < .001), activities of daily living (mean difference 0.45, 10.8 SD, 0.13 SE [90% CI, 0.24 to 0.66], P < .001), sports and recreation (mean difference -0.35, 22.7 SD, 0.27 SE [90% CI, -0.79 to 0.09], P < .001), quality of life (mean difference -0.92, 20.0 SD, 0.24 SE [90% CI, -1.31 to -0.53], P < .001), and the combined KOOS-4 score (mean difference -0.41, 14.5 SD, 0.17 SE [90% CI, -0.70 to -0.13], P < .001). Analyses within specific subsets of patients showed equivalent results between the 2 follow-up evaluations.

CONCLUSION

Equivalent results within patients were found in KOOS values at 1- and 2-year follow-ups after ACL reconstruction. The finding was consistent across all KOOS subscales and for all evaluated subsets of patients. This result implies that there is no additional value in capturing both 1- and 2-year KOOS outcomes after ACL reconstruction. However, these findings of equivalence at 1- and 2-year endpoints do not alleviate the need for longer follow-up periods.

Graft Diameter as a Predictor for Revision Anterior Cruciate Ligament Reconstruction and KOOS and EQ-5D Values: A Cohort Study From the Swedish National Knee Ligament Register Based on 2240 Patients

BACKGROUND

Anterior cruciate ligament (ACL) reconstruction (ACLR) using a hamstring tendon (HT) autograft is an effective and widespread method. Recent studies have identified a relationship between the graft diameter and revision ACLR.

PURPOSE

To evaluate the influence of the graft diameter on revision ACLR and patient-reported outcomes in patients undergoing primary ACLR using HT autografts.

STUDY DESIGN

Cohort study; Level of evidence, 2.

METHODS

A prospective cohort study was conducted using the Swedish National Knee Ligament Register (SNKLR) involving all patients undergoing primary ACLR using HT autografts. Patients with graft failure who needed revision surgery (cases) were compared with patients not undergoing revision surgery (controls). The control group was matched for sex, age, and graft fixation method in a 3:1 ratio. Conditional logistic regression was performed to produce odds ratios and 95% CIs. Univariate linear regression analyses were performed for patient-related outcomes. The Knee injury and Osteoarthritis Outcome Score (KOOS) and EuroQol 5 dimensions questionnaire (EQ-5D) values were obtained.

RESULTS

A total of 2240 patients were included in which there were 560 cases and 1680 controls. No significant differences between the cases and controls were found for sex (52.9% male), mean age (21.7 years), and femoral and tibial fixation. The mean graft diameter for the cases was 8.0 ± 0.74 mm and for the controls was 8.1 ± 0.76 mm. In the present cohort, the likelihood of revision surgery for every 0.5-mm increase in the HT autograft diameter between 7.0 and 10.0 mm was 0.86 (95% CI, 0.75-0.99; P = .03). Univariate linear regression analysis found no significant regression coefficient for the change in KOOS or EQ-5D values.

CONCLUSION

In a large cohort of patients after primary ACLR with HT autografts, an increase in the graft diameter between 7.0 and 10.0 mm resulted in a 0.86 times lower likelihood of revision surgery with every 0.5-mm increase. This study provides further evidence of the importance of the HT autograft size in intraoperative decision making.

The Impact of Osseous Malalignment and Realignment Procedures in Knee Ligament Surgery: A Systematic Review of the Clinical Evidence

Background:

Failure rates of knee ligament surgery may be high, and the impact of osseous alignment on surgical outcome remains controversial. Basic science studies have demonstrated that osseous malalignment can negatively affect ligament strain and that realignment procedures may improve knee joint stability.

Hypothesis/Purpose:

The purpose of this review was to summarize the clinical evidence concerning the impact of osseous malalignment and realignment procedures in knee ligament surgery. The hypotheses were that lower extremity malalignment would be an important contributor to knee ligament surgery failure and that realignment surgery would contribute to increased knee stability and improved outcome in select cases.

Study Design:

Systematic review; Level of evidence, 4.

Methods:

According to the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines, a systematic electronic search of the PubMed database was performed in November 2015 to identify clinical studies investigating (A) the influence of osseous alignment on postoperative stability and/or failure rates after knee ligament surgery and (B) the impact of osseous realignment procedures in unstable knees with or without additional knee ligament surgery on postoperative knee function and stability. Methodological quality of the studies was assessed using the Oxford Centre for Evidence-Based Medicine Levels of Evidence and the Coleman Methodological Score (CMS).

Results:

Of the 1466 potentially relevant articles, 28 studies fulfilled the inclusion and exclusion criteria. Average study quality was poor (CMS, 40). For part A, studies showed increased rerupture rate after anterior cruciate ligament (ACL) replacement in patients with increased tibial slope. Concerning the posterior cruciate ligament (PCL)/posterolateral corner (PLC)/lateral collateral ligament (LCL), varus malalignment was considered a significant risk factor for failure. For part B, studies showed decreased anterior tibial translation after slope-decreasing high tibial osteotomy in ACL-deficient knees. Correcting varus malalignment in PCL/PLC/LCL instability also showed increased stability and better outcomes.

Conclusion:

In cases of complex knee instability, the 3-dimensional osseous alignment of the knee should be considered (eg, mechanical weightbearing line and tibial slope). In cases of failed ACL reconstruction, the tibial slope should be considered, and slope-reducing osteotomies are often helpful in the patient revised multiple times. In cases of chronic PCL and/or PLC instability, osseous correction of the varus alignment may reduce the failure rate and is often the first step in treatment. Changes in the mechanical axis should be considered in all cases of instability accompanied by early unicompartmental osteoarthritis.

Technical Considerations in Revision Anterior Cruciate Ligament (ACL) Reconstruction for Operative Techniques in Orthopaedics

As the incidence of anterior cruciate ligament (ACL) reconstruction continues to increase, the rate of revision surgery continues to climb. Revision surgery has inherent challenges that must be addressed in order to achieve successful results. The cause of the primary ACL reconstruction failure should be determined, and careful preoperative planning should be performed to address the cause(s) of failure. Each patient undergoing revision surgery should undergo a thorough history and physical examination, receive full length alignment radiographs, lateral radiographs, 45-degree flexion weight-bearing postero-anterior radiographs, and patellofemoral radiographs. 3-dimensional computed topography (CT) scan should be performed to assess tunnel position and widening. Magnetic resonance imaging (MRI) should be used to assess for intra-articular soft tissue pathology. Meniscal tears, meniscal deficiency, anterolateral capsule injuries, bony morphology, age, activity level, connective tissue diseases, infection, graft choice, and tunnel position can all impact the success of ACL reconstruction surgery. Meniscal lesions should be repaired, and in cases of persistent rotatory instability, extra-articular procedures may be indicated. Furthermore, osteotomies may be needed to correct malalignment or excess posterior tibial slope. Depending on the placement and condition of the original femoral and tibial tunnels, revision surgery may be performed in a single procedure or in a staged manner. In most cases, the surgery can be performed in one procedure. Regardless, the surgeon must communicate with the patient openly regarding the implications of revision ACL surgery and the treatment plan should be developed in a shared fashion between the surgeon and the patient.

Double-bundle anterior cruciate ligament reconstruction is superior to single-bundle reconstruction in terms of revision frequency: a study of 22,460 patients from the Swedish National Knee Ligament Register

PURPOSE

Studies comparing single- and double-bundle anterior cruciate ligament (ACL) reconstructions often include a combined analysis of anatomic and non-anatomic techniques. The purpose of this study was to compare the revision rates between single- and double-bundle ACL reconstructions in the Swedish National Knee Ligament Register with regard to surgical variables as determined by the anatomic ACL reconstruction scoring checklist (AARSC).

METHODS

Patients from the Swedish National Knee Ligament Register who underwent either single- or double-bundle ACL reconstruction with hamstring tendon autograft during the period 2007-2014 were included. The follow-up period started with primary ACL reconstruction, and the outcome measure was set as revision surgery. An online questionnaire based on the items of the AARSC was used to determine the surgical technique implemented in the single-bundle procedures. These were organized into subgroups based on surgical variables, and the revision rates were compared with the double-bundle ACL reconstruction. Hazard ratios (HR) with 95% confidence interval (CI) was calculated and adjusted for confounders by Cox regression.

RESULTS

A total of 22,460 patients were included in the study, of which 21,846 were single-bundle and 614 were double-bundle ACL reconstruction. Double-bundle ACL reconstruction had a revision frequency of 2.0% (n = 12) and single-bundle 3.2% (n = 689). Single-bundle reconstruction had an increased risk of revision surgery compared with double-bundle [adjusted HR 1.98 (95% CI 1.12-3.51), p = 0.019]. The subgroup analysis showed a significantly increased risk of revision surgery in patients undergoing single-bundle with anatomic technique using transportal drilling [adjusted HR 2.51 (95% CI 1.39-4.54), p = 0.002] compared with double-bundle ACL reconstruction. Utilizing a more complete anatomic technique according to the AARSC lowered the hazard rate considerably when transportal drilling was performed but still resulted in significantly increased risk of revision surgery compared with double-bundle ACL reconstruction [adjusted HR 1.87 (95% CI 1.04-3.38), p = 0.037].

CONCLUSIONS

Double-bundle ACL reconstruction is associated with a lower risk of revision surgery than single-bundle ACL reconstruction. Single-bundle procedures performed using transportal femoral drilling technique had significantly higher risk of revision surgery compared with double-bundle. However, a reference reconstruction with transportal drilling defined as a more complete anatomic reconstruction reduces the risk of revision surgery considerably.

LEVEL OF EVIDENCE

III.

A Review of Databases Used in Orthopaedic Surgery Research and an Analysis of Database Use in Arthroscopy: The Journal of Arthroscopic and Related Surgery

PURPOSE

The purpose of this study was to evaluate how database use has changed over time in Arthroscopy: The Journal of Arthroscopic and Related Surgery and to inform readers about available databases used in orthopaedic literature.

METHODS

An extensive literature search was conducted to identify databases used in Arthroscopy and other orthopaedic literature. All articles published in Arthroscopy between January 1, 2006, and December 31, 2015, were reviewed. A database was defined as a national, widely available set of individual patient encounters, applicable to multiple patient populations, used in orthopaedic research in a peer-reviewed journal, not restricted by encounter setting or visit duration, and with information available in English.

RESULTS

Databases used in Arthroscopy included PearlDiver, the American College of Surgeons National Surgical Quality Improvement Program, the Danish Common Orthopaedic Database, the Swedish National Knee Ligament Register, the Hospital Episodes Statistics database, and the National Inpatient Sample. Database use increased significantly from 4 articles in 2013 to 11 articles in 2015 (P = .012), with no database use between January 1, 2006, and December 31, 2012.

CONCLUSIONS

Database use increased significantly between January 1, 2006, and December 31, 2015, in Arthroscopy.

LEVEL OF EVIDENCE

Level IV, systematic review of Level II through IV studies.

Tunnel widening in single- versus double-bundle anterior cruciate ligament reconstructed knees

PURPOSE

The consequence of tunnel widening after ACL reconstructions is foremost of importance in case of revision surgery. Tunnel expansion leads to bone loss close to the joint, and additional surgery with bone grafting prior to revision surgery might be necessary. The purpose of the study was to measure widening of the tunnels in single-bundle (SB) and double-bundle (DB) ACL reconstructed knees during the first year after surgery, detected by a novel, semi-automated 3D CT imaging modality. Our hypothesis was that there would be a difference between the initial tunnel size and the size measured one year post-operatively due to the tunnel widening process. Further, the purpose was to evaluate whether there were any differences in the amount of tunnel widening between the two surgical techniques.

METHODS

Twenty patients who underwent DB ACL reconstruction, and 22 patients who underwent SB ACL reconstruction, performed a CT scan of the bony tunnels, during their first days after surgery and one year post-operatively. The CT scans were transformed into 3D CT reconstructions, and the tunnels were measured with the "best-fit cylinder" method, measurements at the level of tunnel aperture and 10.0 mm from the joint line.

RESULTS

All tunnels in the DB and SB ACL reconstructed knees exhibited widening during the first year after the operation (p < 0.001). The SB femoral tunnels showed more widening compared to the DB femoral AM tunnels (1.4 ± 0.9 vs. 0.5 ± 0.6 mm) (p < 0.001), and the SB tibial tunnels widened more compared to the DB tibial PL tunnels (1.0 ± 1.0 vs. 0.5 ± 0.6) (p < 0.043).

CONCLUSION

All tunnels widened during the first year after the ACL reconstruction with a larger amount of widening in the SB tunnels compared to the DB femoral AM tunnels and the DB tibial PL tunnels. This is the first study to detect tunnel widening in DB reconstructed knees through a semi-automated 3D CT imaging modality.

LEVEL OF EVIDENCE

Prospective cohort study, Level III.

Anatomic Oblong Double Bundle Anterior Cruciate Ligament Reconstruction

Double-bundle anterior cruciate ligament (ACL) reconstruction using hamstring tendon grafts is a standard procedure for ACL injury. However, its clinical effectiveness is not always satisfactory. One cause of this was problems with the graft-tunnel healing of the posterolateral bundle (PLB) on the femur. To solve this problem, we devised a new anatomic ACL reconstruction technique to improve the graft-tunnel healing of the femoral PLB by using a single-bundle with one bone tunnel on the femoral side and a double-bundle on the tibial side. We have performed 40 procedures with excellent results and no cases of intra- or postoperative complication. This procedure can help improve the graft-tunnel healing around the femoral bone tunnel aperture for the PLB.