Increased Risk of Revision After Anterior Cruciate Ligament Reconstruction With Soft Tissue Allografts Compared With Autografts: Graft Processing and Time Make a Difference

Improvements in Quality, Safety and Costs Associated with Use of Implant Registries Within a Health System

BACKGROUND

Clinical quality registries (CQRs) are intended to enhance quality, safety, and cost reduction using real-world data for a self-improving health system. Starting in 2001, Kaiser Permanente established several medical device CQRs as a quality improvement initiative. This report examines the contributions of these CQRs on improvement in health outcomes, changes in clinical practice, and cost-effectiveness over the past 20 years.

METHODS

Eight implant registries were instituted with standardized collection from the electronic health record and other institutional data sources of patient characteristics, medical comorbidities, implant attributes, procedure details, surgical techniques, and outcomes (including complications, revisions, reoperations, hospital readmissions, and other utilization measures). A rigorous quality control system is in place to improve and maintain the quality of data. Data from the Implant Registries form the basis for multiple quality improvement and patient safety initiatives to minimize variation in care, promote clinical best practices, facilitate recalls, perform benchmarking, identify patients at risk, and construct reports about individual surgeons.

RESULTS

Following the inception of the Implant Registries, there was an observed (1) reduction in opioid utilization following orthopedic procedures, (2) reduction in use of bone morphogenic protein during lumbar fusion allowing for cost savings, (3) reduction in allograft for anterior cruciate ligament reconstruction and subsequent decrease in organizationwide revision rates, (4) cost savings through expansion of same-day discharge programs for joint arthroplasty, (5) increase in the use of cement fixation in the hemiarthroplasty treatment of hip fracture, and (6) organizationwide discontinuation of an endograft device associated with a higher risk for adverse outcomes following endovascular aortic aneurysm repair.

CONCLUSION

The use of Implant Registries within our health system, along with clinical leadership and organizational commitment to a learning health system, was associated with improved quality and safety outcomes and reduced costs. The exact mechanisms by which such registries affect health outcomes and costs require further study.

Various Definitions of Failure Are Used in Studies of Patients Who Underwent Anterior Cruciate Ligament Reconstruction

Purpose

To conduct a literature review to assess the definitions of anterior cruciate ligament reconstruction (ACLR) failure used throughout the orthopaedic literature.

Methods

A systematic search of Embase, Ovid Medline, SPORTDiscus, and Web of Science was conducted by a university librarian to identity level I-IV clinical studies on ACLR failure. Inclusion criteria consisted of patients who underwent ACLR and included a definition of failure of ACLR. Patients who underwent anterior cruciate ligament (ACL) repairs, animal/cadaver studies, review studies, non-English language articles, and non-full text articles were excluded. Failure data were extracted from each study and categorized. Other data that were extracted included follow-up time after ACLR, failure reoperation rate, and failure reoperation procedure. Descriptive statistics was used to analyze the data.

Results

Out of 2,775 studies, 104 (3.75%) met inclusion criteria and were analyzed in this review. The most common definition of ACLR failure included the use of a physical examination, specifically Lachman's test (21/104 [20.2%]), anterior laxity assessment, or a Pivot-Shift test (24/104 [35.2%]) or undergoing or requiring revision ACLR (39/104 [37.5%]). Although some studies used quantitative tests or imaging to help define "failure," others simply defined it as graft rerupture that was otherwise not defined (22/104 [22.5%]). Other common definitions included: the use of imaging (magnetic resonance imaging/radiographs) to confirm graft re-rupture (37/104 [35.6%]), patient-reported outcomes (recurrent instability)/patient reported outcomes measures (International Knee Documentation Committee [IKDC], Knee injury and Osteoarthritis Outcome Score [KOOS], Tegner) (18/104 [17.3%]), and the use of an arthrometer (KT-1000/2000, Rollimeter, or Kneelax) (17/104 [16.3%]). The least common definitions included graft failure or rerupture confirmed by arthroscopy (13/104 [12.5%]) and nonrevision surgery (2/104 [1.0%]). The failure rate of this procedure ranged from 0% to 100% depending on the definition of "failure."

Conclusion

In this study, we found that a variety of definitions of failure are used among studies published in the orthopaedic literature. The most common criteria for failure of ACLR were the results of physical examination tests (35%), the need for undergoing a revision ACLR (36%), and the use of imaging to diagnose the failure (34%). About 17% of studies included in this review used patient-reported outcomes, specifically recurrent instability, or PROMs (IKDC, KOOS, Tegner) in their assessment of failure of ACLR. The least used definitions of "failure" of ACLR included nonrevision ACLR surgery (2%). Although some studies used similar tests or categories in their definition of failure, there were a variety of score and grade cutoff points between them.

Level of Evidence

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

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.

Knee Extensor Mechanism Complications After Autograft Harvest in ACL Reconstruction: A Systematic Review and Meta-analysis

Background

Existing systematic reviews have sought to characterize the relative donor-site morbidity of bone-patellar tendon-bone (BTB) and quadriceps tendon (QT) grafts after anterior cruciate ligament reconstruction (ACLR). However, no studies have reported the pooled proportions of patellar fractures and donor tendon ruptures across the body of literature.

Purpose

To estimate the proportion of patellar fractures, patellar tendon ruptures, and QT ruptures associated with BTB or QT autograft harvest during ACLR using published data.

Study Design

Systematic review; Level of evidence, 4.

Methods

A meta-analysis was conducted according to the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines using 3 online databases (PubMed, Scopus, and Web of Science). A total of 800 manuscripts were included in the initial research of peer-reviewed articles in English that reported extensor mechanism complications associated with graft harvest in patients after ACLR. Pooled proportions of patellar fractures, patellar tendon ruptures, and QT ruptures were calculated for each graft type (BTB, QT) using a random-effects model for meta-analysis.

Results

A total of 28 studies were analyzed. The pooled proportion of patellar fractures was 0.57% (95% CI, 0.34%-0.91%) for the BTB harvest and 2.03% (95% CI, 0.78%-3.89%) for the QT harvest. The proportion of patellar tendon ruptures was 0.22% (95% CI, 0.14%-0.33%) after the BTB harvest, and the proportion of QT ruptures was 0.52% (95% CI, 0.06%-1.91%) after the QT harvest. The majority of included studies (16/28 [57.1%]) had an evidence level of 4.

Conclusion

Based on the current literature, the proportion of extensor mechanism complications after ACLR using either a BTB or a QT autograft is low, indicating that the extensor mechanism harvest remains a safe option. A higher proportion of patellar fractures was noted for QT grafts and a higher proportion of donor tendon ruptures was noted for QT grafts compared with BTB grafts.

Graft choices for paediatric anterior cruciate ligament reconstruction: State of the art

The paediatric population is at particularly high risk for anterior cruciate ligament (ACL) injuries due to high rates of sports participation. Other risk factors for ACL injuries in children include but are not limited to being female, generalised ligamentous laxity, a high body mass index (BMI), and poor neuromuscular control. ACL reconstruction (ACLR) is commonly done to treat ACL injuries and allow for return to sports and daily activities. ACL repair is another option with ongoing techniques being developed. The high rates of graft failure in children reported in recent publications on ACL repair are very concerning. Special consideration must be taken in ACLR in the skeletally immature patient due to the risk of growth-related complications, such as limb deformity or growth arrest, that can arise from drilling across or disrupting the physis. Graft choices for paediatric ACLR include iliotibial band (ITB) over the top and over the front, hamstring autograft, bone patellar tendon bone (BTB) autograft, quadriceps tendon autograft, and allograft. Factors for each graft choice to consider include graft size, graft failure rates, donor site morbidity, requirement for bony tunnels, the post-op rehabilitation process, and return to sport outcomes. Each graft has its benefits and disadvantages for the individual patient, depending on age, skeletal maturity, and goals for recovery. Lateral extra-articular tenodesis (LET) is another option to consider with paediatric ACLR because LET has been shown to decrease the re-rupture rate in adult ACLR. After surgery, patient follow-up until at least the growth plates are closed is important. This article aims to provide an overview and comparison of the various graft types to aid in the graft choice decision making process for paediatric ACLR.

Current trends in graft choice for primary anterior cruciate ligament reconstruction - part II: In-vivo kinematics, patient reported outcomes, re-rupture rates, strength recovery, return to sports and complications

Postoperative patient satisfaction after anterior cruciate ligament reconstruction (ACL-R) is influenced mainly by the degree of pain, the need for reoperation, and functional performance in daily activities and sports. Graft choice has shown to have an influence on postoperative outcomes after ACL-R. While patient reported outcomes measurements do not differ between graft options, evidence shows that normal knee kinematics is not fully restored after ACL-R with an increase in postoperative anterior tibial translation (ATT). Postoperative graft rupture rates seem to favor bone-patella-tendon-bone (BPTB) and quadriceps tendon (QT) autografts over HT or allografts. While return to sports rates seem comparable between different graft types, postoperative extensor strength is reduced in patients with BPTB and QT whereas flexion strength is weakened in patients with HT. Postoperative donor site morbidity is highest in BPTB but comparable between HT and QT. With all graft options having advantages and drawbacks, graft choice must be individualized and chosen in accordance with the patient.

Autograft and Nonirradiated Allograft for Anterior Cruciate Ligament Reconstruction Demonstrate Similar Clinical Outcomes and Graft Failure Rates: An Updated Systematic Review

Purpose

To perform an updated systematic review comparing the clinical outcomes of autograft versus nonirradiated allograft for anterior cruciate ligament reconstruction (ACLR).

Methods

A systematic review was conducted according to the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines by searching PubMed, the Cochrane Library, and Embase to identify comparative studies directly comparing outcomes of primary ACLR with autograft versus nonirradiated allograft with a minimum 2-year follow-up. The search terms used were: “anterior cruciate ligament” AND autograft AND allograft AND (irradiation OR non-irradiated). Patients were evaluated based on graft failure rates, the Objective International Knee Documentation Committee (IKDC) score, anteroposterior laxity, and patient-reported outcomes (Subjective IKDC score, the visual analog scale [VAS], the Cincinnati Knee Rating System, Lysholm, and Tegner scores). Risk of bias was assessed using the ROBINS-I and Cochrane Collaboration’s risk of bias tool for non-randomized and randomized studies, respectively.

Results

Sixteen studies (3 Level I, 7 Level II, 6 Level III) met inclusion criteria, including a total of 15,502 patients undergoing ACLR with autograft and 1,577 with nonirradiated allograft. The average follow-up ranged from 24.0 to 132.0 months. Graft failure ranged from 0% to 9.4% of patients in the autograft group and 0% to 26.5% in the allograft group. Two studies showed greater failure rates among younger patients in the allograft group. There were no significant differences between the Objective IKDC score, anteroposterior laxity, or patient-reported outcomes between the groups within any of the included studies (P > .05).

Conclusions

Autograft and nonirradiated allograft for primary ACLR demonstrate similar patient-reported outcomes and graft failure rates.

Level of Evidence

III, systematic review of level I-III studies.

Return to Baseline Physical Activity After Bone-Patellar Tendon-Bone Versus Hamstring Tendon Autografts for Anterior Cruciate Ligament Reconstruction: A Systematic Review and Meta-analysis of Randomized Controlled Trials

BACKGROUND

Bone-patellar tendon-bone (BPTB) and hamstring tendon (HT) autografts are the most utilized grafts for primary anterior cruciate ligament (ACL) reconstruction. The ability of a patient to return to a preinjury level of physical activity is a key consideration in choice of graft; the influence of graft choice on this metric lacks consensus in the literature.

PURPOSE

To assess the effects of autograft choice (BPTB vs HT) for primary ACL reconstruction on return to baseline level of physical activity and/or sports participation.

STUDY DESIGN

Meta-analysis; Level of evidence, 1.

METHODS

A systematic review of randomized controlled trials comparing the use of BPTB and HT autografts for primary ACL reconstruction was conducted. The electronic databases EMBASE, MEDLINE, Cochrane CENTRAL, and Web of Science were comprehensively queried through September 23, 2019. The primary outcome was return to preinjury level of activity/sports. Secondary outcomes included knee stability testing (Lachman, KT-1000 arthrometer, and pivot-shift tests) and clinical subjective knee scores (Tegner, Cincinnati, International Knee Documentation Committee, and Lysholm). Two independent reviewers were involved in the screening of titles and abstracts, data extraction, and the assessment of risk of bias. Meta-analyses were performed respecting the Cochrane Handbook for Systematic Reviews of Intervention.

RESULTS

A total of 29 studies (N = 3099 patients) were eligible for this review, of which 13 (n = 1029 patients) reported on return to baseline level of sports as an endpoint. The risk ratio (RR) of using BPTB vs HT on return to baseline sport level was 1.03 (0.91-1.17; P = .63). Absence of a positive pivot-shift test was the only secondary outcome, with a statistically significant RR of 0.66 (95% CI, 0.50-0.86) in favor of BPTB autografts (P = .002).

CONCLUSION

In reviewing the current literature, no recommendation can be made on the optimal graft choice when using a return to baseline level of physical activity and/or sports participation as a primary metric.

Case Report Demonstrating Multifactorial Risks of Anterior Cruciate Ligament Re-tear Injuries and Appropriate Response Among Those With High Chance of Recurrence

We present the case of a collegiate football player with an extensive bilateral ligamentous knee injury history to elucidate the mechanisms and possible explanations behind why some athletes sustain recurrent injuries. We hope to initiate thought on altering rehabilitation schedules for athletes who are at an increased risk of re-injury. A 21-year-old collegiate American football player presented with a re-tear of his left anterior cruciate ligament (ACL) and medial meniscus following reconstructive surgery. The initial injury occurred to the patient when he was 15 and suffered a right ACL, lateral collateral ligament, and lateral meniscus tear in a non-contact injury. At the age of 19, he suffered his second injury, a contact-associated left ACL tear. Upon return to play six months following the left ACL tear, the patient sustained a non-contact bucket handle tear of the right medial meniscus. One year later, he presented with a re-tear of his left ACL. His initial left and right ACLs were repaired with hamstring autografts, and his current left ACL was repaired with a bone-patellar tendon-bone graft. This case illustrates an all too common situation plaguing the modern orthopedic sports medicine surgeon. At what point should a surgeon diverge from the standard rehabilitation schedule of ACL surgery due to a patient being at too high of a risk for a re-tear? We propose further investigations into risk factors as well as rehabilitation protocols to help surgeons identify and optimize treatment for these patients.

ACL autograft reconstruction revisions with tendon allografts: Possibilities and outcomes. A one-year follow-up of 39 patients

BACKGROUND

The number of anterior cruciate ligament (ACL) reconstructions is steadily rising in France. Re-tear rates of up to 25% have been reported and graft selection remains a notable challenge. Allografts, although rarely used in France, can be a viable option. The primary objective of this study was to demonstrate the benefits of ACL revision with allografts, by determining subjective scores (IKDC score and KOOS), measuring laxity, and evaluating the rate of return to sports.

HYPOTHESIS

Tendon allografts are reliable and can be used in France for ACL reconstruction revision.

MATERIAL AND METHODS

We conducted a retrospective study including 39 patients managed in two centres between 2004 and 2016 and followed up for at least a year. Patients were eligible if they had undergone tendon allograft reconstruction for ACL revision with or without rupture of a peripheral plane. We excluded underage patients and patients with a history of ligament injury in the contralateral knee. Mean age was 32 years. The allografts were extensor mechanisms, anterior or posterior tibial tendons, fascia lata tendons, hamstring tendons, and a short fibular tendon. They were obtained from French and Belgian tissue banks. They were used for the reconstruction of 39 ACLs and 11 collateral ligaments. The IKDC score and KOOS were determined in all patients. Laximetry was performed in 31 patients by an independent examiner.

RESULTS

Mean follow-up was 3.5 years. Arthroscopic release was required in one patient, and 2 patients experienced re-tears. No deep surgical site infections were recorded. The subjective IKDC score and the KOOS improved significantly, from 53.6 to 80.7 and from 60.4 to 83.2, respectively. Mean postoperative differential laxity was 1.4mm (KT 1000) and 1.6mm (GNRB®). Of the 3 patients who were professional athletes, 2 had returned to sports at the same level one year later, and among the recreational athletes, 54% had resumed their previous sporting activities.

CONCLUSION

In the setting of complex ligament reconstruction revision, tendon allografts are reliable and can be used in France.

LEVEL OF EVIDENCE

IV; retrospective cohort study.

Optimizing anterior cruciate ligament reconstruction: Individualizing the decision-making process using data from the Kaiser Permanente ACLR Registry: 2018 OREF award paper

Despite years of study, controversy remains regarding the optimal graft for anterior cruciate ligament reconstruction (ACLR), suggesting that a single graft type is not ideal for all patients. A large community based ACLR Registry that collects prospective data is a powerful tool that captures information and can be analyzed to optimize surgery for individual patients. The studies highlighted in this paper were designed to optimize and individualize ACLR surgery and have led to changes in surgeon behavior and improvements in patient outcomes. Kaiser Permanente (KP) is an integrated health care system with 10.6 million members and more than 50 hospitals. Every KP member who undergoes an ACLR is entered into the Registry, and prospectively monitored. The Registry uses a variety of feedback mechanisms to disseminate Registry findings to the ACLRR surgeons and appropriately influence clinical practices and enhance quality of care. Allografts were found to have a 3.0 times higher risk of revision than bone-patellar tendon-bone (BPTB) autografts. Allograft irradiation >1.8 Mrad, chemical graft processing, younger patients, BPTB allograft, and male patients were all associated with a higher risk of revision surgery. By providing feedback to surgeons, overall allograft use has decreased by 27% and allograft use in high-risk patients ≤21 years of age decreased 68%. We have identified factors that influence the outcomes of ACLR. Statement of Clinical Significance: We found that information derived from an ACLR Registry and shared with the participating surgeons directly decreased the use of specific procedures and implants associated with poor outcomes.

Anterior Cruciate Ligament Reconstruction Using Bone-Patellar Tendon-Bone Allograft in Patients Aged 50 and Older Leads to Improved Activity Levels and Acceptable Patient-Reported Outcomes

PURPOSE

To evaluate patient-reported outcomes in patients aged 50 years and older undergoing anterior cruciate ligament reconstruction (ACLR) using bone-patellar tendon-bone (BPTB) allograft with minimum 2-year follow-up.

METHODS

A retrospective review was performed on a consecutive series of patients aged 50 and older who underwent ACLR using BPTB allograft by a single surgeon with minimum 2-year follow-up. Postoperative International Knee Documentation Committee (IKDC), Lysholm, and Physical Component Summary of the 12-item Short-Form Health Survey were used to assess outcomes, as well as preoperative and postoperative Tegner activity scores, which were compared using a paired sample t test.

RESULTS

Fifty patients met inclusion criteria, with a mean age of 55.3 ± 4.4 years and mean follow-up of 4.8 ± 1.9 years. Tegner activity scores improved from a mean preoperative score of 3.26 to a mean postoperative score of 5.25 (P < .001). The mean postoperative scores for Lysholm, IKDC, and Physical Component Summary were 87.3, 81.1, and 54.3, respectively. In total, 36 (72%) patients achieved a patient acceptable symptom state score for IKDC and 37 (74%) patients achieved a minimal clinically important difference for Tegner activity score. Thirty-eight (76%) patients reported good-to-excellent results, 6 (12%) patients reported fair results, and 6 (12%) patients reported poor results.

CONCLUSIONS

ACLR with BPTB allograft in patients aged 50 and older leads to good patient-reported outcomes with significantly increased postoperative activity status at a minimum 2-year follow-up.

LEVEL OF EVIDENCE

Level IV, therapeutic case series.

The impact of graft type on rehabilitation outcomes following ACL reconstruction: Bone patellar tendon bone versus quadriceps tendon grafts

OBJECTIVE

The aims of this study were to 1) compare the dosage of physical therapy provided for patients following an anterior cruciate ligament reconstruction (ACL-R) with either quadriceps or bone-patellar tendon-bone (BPTB) graft type and their resulting outcomes and 2) investigate the frequency therapists documented surgical graft type.

DESIGN

Retrospective observational.

SETTING

Outpatient orthopedics.

PARTICIPANTS

Data was collected from the electronic medical records of 212 patients: BPTB (41) and quadriceps tendon (33) were analyzed. Forty-eight cases were other graft types and 90 were unspecified.

MAIN OUTCOME MEASURE

An independent samples t-test was used to compare differences in knee range of motion (ROM) and Knee Functional Status (FS) between BPTB and quadriceps grafts.

RESULTS

There were no differences in knee flexion (p = 0.148) or extension (p = 0.305) ROM between groups at discharge. The quadriceps group achieved greater improvement in functional outcomes (p < 0.001). The quadriceps group received more sessions (p = 0.021) and a longer duration of care (p = 0.007).

CONCLUSIONS

The significant difference in treatment dosage makes it difficult to conclude which graft is superior. It is unknown if the frequent omission of graft type in the patient chart is an indication of poor documentation practice or a lack of perceived importance in knowing the graft type for PT.

Aseptically Processed Allograft Implantation: A Safe Strategy for Knee Ligament Reconstructions

Postoperative infections after allograft implantation is a major concern in knee ligament reconstructions considering the theoretical risk of disease transmission and its potential severity. Here, we aimed to evaluate the postoperative infection rate after knee ligament reconstructions using aseptically processed allografts, and provide an overview of the allografts use in an academic tertiary hospital. A retrospective study was performed evaluating patients who underwent knee ligament reconstructions using aseptically processed allografts, including primary and revision surgeries, from 2005 to 2018. Demographic data, including the type of knee injury and trauma energy, and postoperative data were collected focusing on postoperative infections. Regarding these infected cases, further analyses were performed considering the presenting signs and symptoms, the isolated microorganism identified in culture, the time between graft implantation and diagnosis of infection (defined as acute, subacute, and late), and the need for graft removal. A total of 180 cases of ligament reconstructions were included. The mean follow-up was 8.2 (range: 2.1-15.6) years and the mean age at surgery was 34.1 (± 11.1) years. A total of 262 allografts were implanted in those 180 cases, 93 (35.5%) as bone plug allografts and 169 (64.5%) as soft tissue allografts. Common surgical indications included multiligament reconstruction (57.2%) and primary anterior cruciate ligament (ACL) reconstruction (15%). Seven cases (3.9%) presented postoperative infections. Knee pain (100%) and swelling (100%) were the most prevalent symptoms. Two cases (28.6%) presented sinus tract. Allografts were removed in two cases, the same cases that presented draining sinus (p = 0.04). High-energy trauma was the only statistically associated factor for infection (p = 0.04). No significant association between infection and the type of allograft (p > 0.99) or sex (p = 0.35) were observed. Four cases (57.1%) had monomicrobial staphylococcal infections. Based on that, the allograft-related infection rate was 1.7% (the remaining three infected cases). Nonirradiated, aseptically processed allografts have a low postoperative infection rate in knee ligament reconstructions, being a safe alternative for surgeries that require additional source, increased variety, and quantity of grafts.

Anterior Cruciate Ligament Reconstruction Graft Preference Most Dependent on Patient Age: A Survey of United States Surgeons

PURPOSE

The purpose of this study was to define the anterior cruciate ligament (ACL) reconstruction (ACLR) graft preference of surgeons and to explore factors associated with their predilection.

METHODS

A 15-question survey regarding ACLR graft preference in various situations was completed by 514 American Orthopaedic Society for Sports Medicine and Arthroscopy Association of North America surgeons. Surgeon and practice demographics, along with various patient factors, were evaluated with bivariate and multivariable models for association with surgeon preference. Surgeons were also queried about their preference for their own ACLR. For surgeons who personally sustained an ACL, an additional 6 questions inquired about their experience.

RESULTS

Surgeons reported the 5 most important factors in patient graft choice, in order: patient age, graft failure in literature and practice, pivot sport, and patient preference. Autograft patellar and quadriceps tendon were strongly preferred for younger, pivoting athletes (P < .001), among those with fellowship training (47% vs 33%, P = .006), in academic practices (52% vs 44%, P = .003), and in more sports medicine-specific practices, with a higher number of ACLRs performed per year (P < .001). Northeast, Southeast, Midwest, and Southwest surgeons had lower hamstring autograft preference (P < .001). Non-fellowship-trained surgeons preferred hamstring autograft (P = .010). Allograft was preferred for older patients (P < .001). Nonsignificant predictors included highest level of athlete for whom an ACLR had been performed, level of athlete serving as team physician, and years in practice. No factors were associated with surgeon preference for their own ACLR despite deeming these factors important for patients. ACL tears were reported by 13% of respondents, with 86% stating it influenced their decision to enter orthopaedics.

CONCLUSIONS

Patient age was the most important factor in graft choice, with patellar and quadriceps tendon autograft the preferred graft for ACLR for younger, pivoting athletes. Fellowship training and practice demographics were also correlated with graft choice for patients.

CLINICAL RELEVANCE

Graft preference for ACLR varies among surgeons and is associated with surgeon experience and patient characteristics, including patient age, type of sport, and patient preference.

Clinical outcome after knee ligament reconstruction with tendon allografts

PURPOSE

The purpose of this study is to investigate the clinical outcome for patients after knee ligament reconstructions with allografts at a university hospital.

METHODS

A total of 33 patients received allografts for reconstructive knee surgery between 2007 and 2017. The follow up evaluation consisted of a clinical knee examination including evaluation of range of motion (ROM), lateral and medial laxity, the Lachman test, the Pivot shift test, the sag test, the posterior drawer test and checking for patellofemoral pain. The following patient-reported outcome measures (PROMs) were used; the Lysholm Function Score, the Tegner activity score, and the Knee injury and Osteoarthritis Outcome Score (KOOS).

RESULTS

Twenty-one (64%) patients were available for the follow-up evaluation and the mean follow-up time was 4.8 years. A total of 16 out of 21 patients had multiligament injuries of which the ACL was the ligament most frequently ruptured. At the time of follow-up, 14 out of 16 patients (87%) with ACL injury had Lachman test grade 0 or grade 1 + , and 12 out of 13 (92%) had a pivot shift grade 0 or 1 + . The mean Lysholm Score was 74. All mean KOOS subscale values were ≥ 59 at the follow-up. The preoperative Tegner activity score was 3 (range, 1-6) and 4 (range, 2-6) at follow up. There were no deep postoperative infections. A total of 19 out of 21 patients (90%) reported that they would have undergone surgery again had they known the clinical outcome in advance.

CONCLUSIONS

The patients improved from the preoperative score to the follow-up score in the knee-related Quality of Life (QoL) KOOS subscale. None of the patients were diagnosed with deep postoperative infections.

Anatomic Anterior Cruciate Ligament Reconstruction Using Rectangular Bone-Tendon- Bone Autograft Versus Double-Bundle Hamstring Tendon Autograft in Young Female Athletes

Purpose

To assess the clinical outcomes comparing rectangular bone–tendon–bone (BTB) grafts and double-bundle hamstring tendon (HM) grafts used for anatomic anterior cruciate ligament (ACL) reconstruction in young female athletes.

Methods

From January 2014 to November 2017, young female athletes 20 years or younger who underwent primary ACL reconstructions by a single surgeon were identified. Patients with concomitant injuries, not being a regular sports participant, the existence of contralateral ACL reconstruction, and who did not have a minimum of 1-year follow-up were excluded. We searched the rate and time for return-to-play, clinical outcomes including chronological instrumental side-to-side tibial translation difference, and muscle strength. Second ACL injury rates between the 2 groups during follow-up period were evaluated.

Results

Twenty-seven BTB ACL reconstructions and 29 HM ACL reconstructions were performed. The mean follow-up periods were 35.2 months in the BTB group and 33.8 months in the HM group. The BTB group showed better knee stability in mean side-to-side translational difference via arthrometric testing of 0.6 mm in the BTB versus 1.7 mm in the HM group at 5 months (P = .01) and 1.1 mm and 2.0 mm at 12 months, respectively (P = .02). There was no significant side-by-side difference in quadriceps muscle strength ratio, but the hamstring muscle strength was significantly better in the BTB group. The graft reinjury rate in the BTB group and the HM group was 0% (0/27) and 10.3% (3/29) (P = .09), respectively. In contrast, contralateral ACL injuries occurred in 17.3% (4/27) of the BTB group and 3.5% (1/29) of the HM group (P = .12).

Conclusions

For young female athletes aged 20 years or younger, the BTB group had better knee instrumental stability than the HM group without range of motion loss or knee extensor muscle strength deficit. Although there was no statistical significance in terms of second ACL injury, we observed fewer graft rerupture and an increasing rate of contralateral ACL injuries in the BTB group.

Level of Evidence

Level III, retrospective comparative study.

Revision ACL Reconstruction: Principles and Practice

INTRODUCTION

The incidence of anterior cruciate ligament reconstruction (ACLR) surgeries is increasing and so is the number of revision surgeries for a failed ACLR. The spectrum of ACL failure includes symptoms of recurrent instability, pain, and/or stiffness.

DISCUSSION

Factors contributing to ACL failure may be classified as patient-related, surgeon-related, and biological factors. Of these, tunnel malposition and recurrent trauma are the most common causes. Detailed patient assessment, imaging, and studying details of the index surgery are critical prior to planning revision surgery. Infection has to be ruled out prior to planning any reconstructive surgical procedure. Osseous malalignment in the coronal or sagittal planes would also need correction along with or prior to revision ACL surgery. Revision ACL reconstruction maybe performed as a one-stage or two-stage procedure. Severe tunnel dilatation, infection, or arthrofibrosis necessitates a two-stage approach. Autografts are preferred for revision ACL due their lesser re-tear rates and better outcomes. Associated meniscus tears and cartilage injuries are more common in revision than in primary surgery and need to be managed appropriately. Extra-articular reconstruction for controlling anterolateral instability is frequently required as well.

CONCLUSION

Revision ACL reconstruction is a complex undertaking due to limited graft options, compromised anatomy and high frequency of associated injuries. Patient expectations must be tempered because functional outcomes and return to pre-injury sports are inferior to a primary surgery.

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.

Use of supercritical carbon dioxide technology for fabricating a tissue engineering scaffold for anterior cruciate ligament repair

Tissue-engineered grafts may be useful in Anterior Cruciate Ligament (ACL) repair and provide a novel, alternative treatment to clinical complications of rupture, harvest site morbidity and biocompatibility associated with autografts, allografts and synthetic grafts. We successfully used supercritical carbon dioxide (Sc-CO₂) technology for manufacturing a “smart” biomaterial scaffold, which retains the native protein conformation and tensile strength of the natural ACL but is decellularized for a decreased immunogenic response. We designed and fabricated a new scaffold exhibiting (1) high tensile strength and biomechanical properties comparable to those of the native tissue, (2) thermodynamically-stable extra-cellular matrix (ECM), (3) preserved collagen composition and crosslinking, (4) a decellularized material milieu with potential for future engineering applications and (5) proven feasibility and biocompatibility in an animal model of ligament reconstruction. Because of the “smart” material ECM, this scaffold may have the potential for providing a niche and for directing stem cell growth, differentiations and function pertinent to new tissue formation. Sc-CO₂-related technology is advanced and has the capability to provide scaffolds of high strength and durability, which sustain a lifetime of wear and tear under mechanical loading in vivo.

Quadriceps tendon autograft for anterior cruciate ligament reconstruction is associated with high revision rates: results from the Danish Knee Ligament Registry

PURPOSE

The quadriceps tendon (QT) has recently gained interest as an anterior cruciate ligament reconstruction (ACLR) autograft. There is a paucity of data from large cohort studies on failures and revision rates after ACLR using the QT graft. The purpose of the present study is to use the Danish Knee Ligament Reconstruction Registry (DKRR) to compare revision rates, objective knee stability and subjective clinical outcomes in patients who have undergone ACLR with QT, hamstring tendon (HT), and patellar tendon (PT) as a graft for ACLR. It was hypothesized that QT autografts would result in similar objective knee stability and revision rates as HT and PT autografts.

METHODS

Data on primary ACLRs in the DKRR from 2005 through 2017 were analyzed. Knee injury and Osteoarthritis Outcome Scores (KOOS), Tegner activity scale scores, sagittal knee laxity, pivot-shift tests at 1-year follow-up and revision rates at 2-year follow-up were compared for the three autograft cohorts.

RESULTS

A total of 531 QT, 14,213 HT and 1835 PT ACLR were registered in the DKLR between 2005 and 2017. QT autograft was associated with statistically significant increased laxity (1.8 mm) compared to HT autograft (1.5 mm) (p < 0.001) and more positive pivot shift. There was a significant higher revision rate for QT (4.7%), compared to PT (1.5%) and HT (2.3%) autografts at 2-year follow-up (p < 0.002).

CONCLUSION

Quadriceps tendon autografts for ACLR was associated with higher revision rates than HT and PT grafts. QT graft was also associated with small increased objective knee laxity and more positive pivot shift than HT and PT grafts.

LEVEL OF EVIDENCE

III.

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.

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 Risk of Soft Tissue Allograft Versus Hybrid Graft After Anterior Cruciate Ligament Reconstruction

BACKGROUND

When a harvested hamstring autograft is deemed by the surgeon to be of inadequate diameter, the options include using the small graft, using another autograft from a different site, augmenting with an allograft (hybrid graft), using a different configuration of the graft (eg, 5- or 6-stranded), or abandoning the autograft and using allograft alone. A small graft diameter is associated with a higher revision risk, and using another autograft site includes added harvest-site morbidity; therefore, use of a hybrid graft or an allograft alone may be appealing alternative options. Revision risk for hybrid graft compared with soft tissue allograft is not known.

PURPOSE

To evaluate the risk for aseptic revision surgery after primary anterior cruciate ligament reconstruction (ACLR) using a soft tissue allograft compared with ACLR using a hybrid graft in patients 25 years and younger.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

Data from a health care system's ACLR registry were used to identify primary isolated unilateral ACLRs between 2009 and 2016 using either a hybrid graft (hamstring autograft with soft tissue allograft) or a soft tissue allograft alone. Multivariable Cox proportional hazards regression was used to evaluate risk for aseptic revision after ACLR according to graft used after adjustment for age, allograft processing, tunnel drilling technique, and region where the primary ACLR was performed.

RESULTS

The cohort included 2080 ACLR procedures; a hybrid graft was used for 479 (23.0%) ACLRs. Median follow-up time was 3.4 years (interquartile range, 1.8-5.1 years). The crude 2-year aseptic revision probability was 5.4% (95% CI, 4.3%-6.7%) for soft tissue allograft ACLR and 3.8% (95% CI, 2.3%-6.4%) for hybrid graft ACLR. After adjustment for covariates, soft tissue allograft ACLR had a higher risk of aseptic revision during follow-up compared with hybrid graft ACLR (hazard ratio, 2.00; 95% CI, 1.21-3.31; P = .007).

CONCLUSION

Soft tissue allografts had a 2-fold higher risk of aseptic revision compared with hybrid graft after ACLR. Future studies evaluating the indications for using hybrid grafts and the optimal hybrid graft diameter is needed.

Comparison of concomitant injuries and patient-reported outcome in patients that have undergone both primary and revision ACL reconstruction-a national registry study

BACKGROUND

Anterior cruciate ligament (ACL) revision surgery has been associated with inferior outcome compared with primary ACL reconstruction. However, this has rarely been investigated in a consecutive cohort limited to patients that have undergone both primary and revision ACL reconstruction. This study aimed to assess differences in outcome and concomitant injuries between primary and revision ACL reconstruction in such a cohort, and to identify predictors of the patient-reported outcome after ACL revision.

METHODS

Patients who had undergone both primary and revision ACL reconstruction were identified in the Swedish National Knee Ligament Registry. Patients aged 13-49 years with hamstring tendon primary ACL reconstruction and data on the Knee Injury and Osteoarthritis Outcome Score (KOOS) on at least one occasion (preoperative or one year postoperatively) at both surgeries were eligible. Concomitant injuries and the KOOS were compared between each patient's primary and revision ACL reconstruction. Linear regression analyses were performed to determine predictors of the one-year KOOS after ACL revision.

RESULTS

A total of 1014 patients were included. Cartilage injuries increased at ACL revision (p < 0.001), as 23.0% had a cartilage injury at ACL revision that was not present at primary ACL reconstruction. The 1-year KOOS was lower after ACL revision compared with primary ACL reconstruction, with the largest difference in the KOOS sports and recreation (5.2 points, SD 32.2, p = 0.002). A posterolateral corner (PLC) injury at ACL revision was a negative predictor of KOOS, with the largest effect on the sports and recreation subscale (β = - 29.20 [95% CI - 50.71; - 6.69], p = 0.011). The use of allograft for ACL revision was an independent predictor of a poorer KOOS QoL (β = - 12.69 [95% CI - 21.84; - 3.55], p = 0.0066) and KOOS₄ (β = - 11.40 [95% CI - 19.24; - 3.57], p = 0.0044).

CONCLUSION

Patients undergoing ACL revision reported a 1-year outcome that was slightly inferior to the 1-year outcome after their primary ACL reconstruction. An ACL revision was associated with an increase in cartilage injuries. A PLC injury at ACL revision and the use of allograft for ACL revision predicted a clinically relevant poorer KOOS one year after ACL revision.

Outcomes Following ACL Reconstruction Based on Graft Type: Are all Grafts Equivalent?

PURPOSE OF REVIEW

Anterior cruciate ligament reconstruction is one of the most common orthopedic procedures performed, accounting for over 200,000 cases annually. Despite the high prevalence, there is still much debate as to the optimal graft choice. The purpose of this review is to evaluate the current literature and discuss the reported outcomes for the most common graft choices.

RECENT FINDINGS

The most common autografts being used include bone-patellar tendon-bone (BPTB), hamstring tendon (HT), and quadriceps tendon (QT). Hamstring tendon might have a slightly higher re-tear rate when compared with BPTB (2.84 versus 2.80). However, BPTB has a higher rate of anterior knee and kneeling pain in the short- and mid-term follow-up. This has not been shown to be the case in long-term follow-up. Allograft is a viable option for revisions and primaries in patients greater than 35 years old; however, re-tear rate increases significantly in younger patients. ACL reconstruction graft choice is a highly studied and yet still exceedingly debated topic. Most large studies report either no significant difference or a small difference in failure rate and outcome scores between the different autograft choices. Allografts have been demonstrated to have an increased risk of failure in younger athletes and should be reserved for revision cases and those aged 35 years and older. Graft choice should ultimately be decided upon based on surgeon comfort and experience and individual patient characteristics.

Quadriceps tendon grafts does not cause patients to have inferior subjective outcome after anterior cruciate ligament (ACL) reconstruction than do hamstring grafts: a 2-year prospective randomised controlled trial

OBJECTIVE

We performed a randomised controlled trial (RCT) in patients undergoing ACL reconstruction (ACLR) using either quadriceps tendon graft (QT) or semitendinosus/gracilis hamstring (STG) graft. We compared subjective outcome (primary outcome) and knee stability, donor site morbidity and function (secondary outcomes).

METHODS

From 2013 to 2015, we included 99 adults with isolated ACL injuries in the RCT. Fifty patients were randomised to QT grafts and 49 to STG grafts and followed for 2 years. Patient evaluated outcomes were performed by subjective International Knee Documentation Committee, Knee Injury and Osteoarthritis Outcome Score, Kujala and Tegner activity scores. Knee laxity was measured with a KT-1000 arthrometer. Donor site morbidity was evaluated by the 'donor site-related functional problems following ACLR score'. One-leg hop test tested limp strength symmetry.

RESULTS

At 2-year follow-up, there was no difference between the two graft groups regarding subjective patient outcome, knee stability and reoperations. Also, at 2 years, donor site symptoms were present in 27% of patients in the QT group and 50% of patients in the STG group. The donor site morbidity score was 14 and 22 for the QT and STG, respectively. Hop test demonstrated lower limp symmetry for QT graft than STG graft of 91% and 97% respectively.

CONCLUSION

QT graft for ACLR did not result in inferior subjective outcome compared with STG graft. However, QT graft was associated with lower donor site morbidity than STG grafts but resulted in more quadriceps muscle strength deficiency than hamstring grafts. Both graft types had similar knee stability outcome.

TRIAL REGISTRATION NUMBER

NCT02173483.

Accelerated Bone Regeneration by Gold-Nanoparticle-Loaded Mesoporous Silica through Stimulating Immunomodulation

Bone repair and regeneration are greatly influenced by the local immune microenvironment. In this regard, the immunomodulatory capability of biomaterials should be considered when evaluating their osteogenic effects. In this study, we investigated the modulatory effects of gold nanoparticle (AuNP)-loaded mesoporous silica nanoparticles (Au-MSNs) on macrophages and the subsequent effects on the behavior of osteoblastic lineage cells. The results demonstrate that Au-MSNs could generate a favorable immune microenvironment by stimulating an anti-inflammatory response and promoting the secretion of osteogenic cytokines by macrophages. As a result, there is an enhancement of osteogenic differentiation in preosteoblastic MC3T3 cells as assessed by the increased expression of osteogenic markers, alkaline phosphatase (ALP) production, and calcium deposition. The immunomodulatory effects and direct osteogenic stimulation by Au-MSNs synergistically increased the osteogenic differentiation capability of MC3T3 cells as a result of crosstalk between Au-MSN-conditioned macrophages and Au-MSN-treated osteoblasts in a coculture system. An in vivo study further revealed that Au-MSNs could accelerate new bone formation in a critical-sized cranial defect site in rats based on computed tomography analysis and histological examination. Together, this novel Au-MSNs could significantly promote osteogenic activity by modulating the immune microenvironment, showing its therapeutic potential for bone tissue repair and regeneration.

[Progress of sterilization and preservation methods for allografts in anterior cruciate ligament reconstruction]

OBJECTIVE

To review the current status and progress of sterilization and preservation for allograft in anterior cruciate ligament reconstruction.

METHODS

The related literature about the sterilization and preservation of allografts in anterior cruciate ligament reconstruction was extensively reviewed and summarized.

RESULTS

There are many sterilization methods for allografts, the most commonly used method is γ-ray irradiation, but the optimal irradiation dose is still unclear. Electron beam irradiation is also available, but excessive dose is harmful to graft shaping. A combined sterilization method combining physics and chemistry methods is still being explored. Cryopreservation is the most commonly used method of preservation. In order to reduce the influence of crystals, the principle of "slow cooling and rapid rewarming" should be adhered to as far as possible.

CONCLUSION

The processing methods of allograft can affect the effectiveness of anterior cruciate ligament reconstruction. The clinical doctors should consider the sterilization and preservation methods in practice.

Allograft for knee ligament surgery: an American perspective

PURPOSE

Allografts are frequently use for ligamentous reconstruction at the knee. In the United States, tissue donation and distribution are highly regulated processes with thorough oversight from private and government entities. Allograft is widely available in the United States and allograft procurement is a large industry with varying procurement, sterilization, processing, and distribution procedures. It is important to understand allograft regulation and processing which may affect graft mechanical properties and biological graft integration.

METHODS

English-language literature, United States government and regulatory agency statues pertaining to allograft procurement, distribution, and usage were reviewed and the findings summarized.

RESULTS

During the processing of allograft, multiple factors including sterilization procedures, irradiation, storage conditions, and graft type all affect the biomechanical properties of the allograft tissue. Biological incorporation and ligamentization of allograft does occur, but at a slower rate compared with autograft. For ligamentous reconstruction around the knee, allograft offers shorter operative time, no donor-site morbidity, but has shown an increased risk for graft failure compared to autograft.

CONCLUSION

This article reviews the regulations on graft tissue within the United States, factors affecting the biomechanics of allograft tissue, differences in allograft tissue choices, and the use of allograft for anterior cruciate ligament reconstruction and multiligamentous knee injury reconstruction.

LEVEL OF EVIDENCE

V.

The use of allograft tissue in posterior cruciate, collateral and multi-ligament knee reconstruction

PURPOSE

Currently both autograft and allograft tissues are available for reconstruction of posterior cruciate, collateral and multi-ligament knee injuries. Decision-making is based on a complex interplay between anatomical structures, functional bundles and varying biomechanical requirements. Despite theoretically better biological healing and reduced risk of disease transmission autografts are associated with donor site morbidity as well as being limited by size and quantity. The use of allografts eliminates donor-site morbidity but raises cost and issues of clinical effectiveness. The purpose of this paper is to review current concepts and evidence for the use of allografts in primary posterior cruciate, collateral and multi-ligament reconstructions.

METHODS

A narrative review of the relevant literature was conducted for PCL, collateral ligament and multi-ligament knee reconstruction. Studies were identified using a targeted and systematic search with focus on recent comparative studies and all clinical systematic reviews and meta-analyses. The rationale and principles of management underpinning the role of allograft tissue were identified and the clinical and functional outcomes were analysed. Finally, the position of postoperative physiotherapy and rehabilitation was identified.

RESULTS

The review demonstrated paucity in high quality and up-to-date results addressing the issue especially on collaterals and multi-ligament reconstructions. There was no significant evidence of superiority of a graft type over another for PCL reconstruction. Contemporary principles in the management of posterolateral corner, MCL and multi-ligament injuries support the use of allograft tissue.

CONCLUSION

The present review demonstrates equivalent clinical results with the use of autografts or allografts. It remains, however, difficult to generate a conclusive evidence-based approach due to the paucity of high-level research. When confronted by the need for combined reconstructions with multiple grafts, preservation of synergistic muscles, and adapted postoperative rehabilitation; the current evidence does offer support for the use of allograft tissue.

LEVEL OF EVIDENCE

IV.

The use of allograft tendons in primary ACL reconstruction

PURPOSE

Graft choice in primary anterior cruciate ligament (ACL) reconstruction remains controversial. The use of allograft has risen exponentially in recent years with the attraction of absent donor site morbidity, reduced surgical time and reliable graft size. However, the published evidence examining their clinical effectiveness over autograft tendons has been unclear. The aim of this paper is to provide a current review of the clinical evidence available to help guide surgeons through the decision-making process for the use of allografts in primary ACL reconstruction.

METHODS

The literature in relation to allograft healing, storage, sterilisation, differences in surgical technique and rehabilitation have been reviewed in addition to recent comparative studies and all clinical systematic reviews and meta-analyses.

RESULTS

Early reviews have indicated a higher risk of failure with allografts due to association with irradiation for sterilisation and where rehabilitation programs and post-operative loading may ignore the slower incorporation of allografts. More recent analysis indicates a similar low failure rate for allograft and autograft methods of reconstruction when using non-irradiated allografts that have not undergone chemically processing and where rehabilitation has been slower. However, inferior outcomes with allografts have been reported in young (< 25 years) highly active patients, and also when irradiated or chemically processed grafts are used.

CONCLUSION

When considering use of allografts in primary ACL reconstruction, use of irradiation, chemical processing and rehabilitation programs suited to autograft are important negative factors. Allografts, when used for primary ACL reconstruction, should be fresh frozen and non-irradiated. Quantification of the risk of use of allograft in the young requires further evaluation.

LEVELS OF EVIDENCE

III.

Allograft tendons are a safe and effective option for revision ACL reconstruction: a clinical review

Revision anterior cruciate ligament reconstruction remains a challenge, especially optimising outcome for patients with a compromised knee where previous autogenous tissue has been used for reconstruction. Allograft tissue has become a recognized choice of graft for revision surgery but questions remain over the risks and benefits of such an option. Allograft tendons are a safe and effective option for revision ACL reconstruction with no higher risk of infection and equivalent failure rates compared to autografts provided that the tissue is not irradiated, or any irradiation is minimal. Best scenarios for use of allografts include revision surgery where further use of autografts could lead to high donor site morbidity, complex instability situations where additional structures may need reconstruction, and in those with clinical and radiologic signs of autologous tendon degeneration. A surgeon needs to be able to select the best option for the challenging knee facing revision ACL reconstruction, and in the light of current data, allograft tissue can be considered a suitable option to this purpose.Level of evidence IV.

Hybrid graft vs autograft in anterior cruciate ligament reconstruction: a meta-analysis

Purpose

We conducted this meta-analysis to evaluate the efficacy of hybrid grafts in anterior cruciate ligament reconstruction (ACLR).

Methods

We performed an electronic search of the Cochrane Library, PubMed, Embase, and ScienceDirect from the inception of these databases to February 2018, based on the terms “anterior cruciate ligament or ACL reconstruction”, “autograft”, “hybrid”, and “augment”. Relevant journals and conference proceedings were searched manually. Quality assessment, data extraction, and calculation of data from the included studies were conducted independently by two reviewers using RevMan 5.1.

Results

One randomized controlled trial and eight nonrandomized controlled trials met inclusion criteria. Larger graft diameters were found in the hybrid-graft group (mean difference −1.47, P=0.0001). There was no significant difference in failure rate (OR 2.13, P=0.21), retearing (OR 2.23, P=0.12), revision of ACLR (OR 1.05, P=0.87) or reoperation (OR 1.27, P=0.35). Subgroup analysis showed that hybrid-graft patients with meniscus injury suffered more revision (OR 4.10, P=0.02) and reoperation (OR 5.74, P=0.001). Both autografts and hybrid grafts performed similarly in most knee-score systems. However, autograft patients had better KT-1000 (mean difference 0.24, P=0.05) and quality-of-life results on the Knee Injury and Osteoarthritis Outcome Score measure (mean difference 7.23, P=0.05).

Conclusion

This meta-analysis of the current literature indicates similar performance of hybrid or autologous grafts in ACLR, though hybrid grafts had larger diameters than autografts. Other potential factors to influence failure, revision, or postoperative knee function, such as irradiation, age at reconstruction, meniscus injury/treatment, and hybrid-graft remodeling, should be investigated further.

Comparison of clinical outcomes after anterior cruciate ligament reconstruction with hamstring tendon autograft versus soft-tissue allograft: A meta-analysis of randomised controlled trials

BACKGROUND

Hamstring tendon autografts and soft-tissue allograft are commonly used for anterior cruciate ligament (ACL) reconstruction. However, the clinical outcomes between these two grafts are controversial. This meta-analysis was performed to compare clinical outcomes of primary ACL reconstruction with hamstring tendon autografts versus soft-tissue allografts.

MATERIALS AND METHODS

PubMed, Embase, and the Cochrane Library were searched through 8 September 2017 to identify randomized controlled studies that compared hamstring tendon autografts with soft-tissue allografts for primary ACL reconstruction. Two authors independently graded the methodological quality of each eligible study using the Cochrane Collaboration tool and extracted relevant data. Statistical heterogeneity among the trials was evaluated with chi-square and I-square tests. A sensitivity analysis was conducted to explore sources of heterogeneity. Subgroup analysis was performed to identify potential differences according to type of reconstruction technique (single-bundle or double-bundle).

RESULTS

Eight studies with 785 combined patients (396 hamstring tendon autografts and 389 soft-tissue allografts) were included. Two studies had a high risk of bias. The other six studies had unclear risk of bias. There were significant differences between the groups in subjective International Knee Documentation Committee (IKDC) score (mean difference [MD], 2.43; 95%CI, 0.69-4.18; p = 0.006), Tegner score (MD, 0.24; 95%CI, 0.03-0.45; p = 0.03), and side-to-side difference (MD, -1.37; 95%CI, -2.44 to -0.30; p = 0.01). There was no significant difference between the groups in Lysholm score, complications, pivot shift test, anterior drawer test, Lachman test, overall IKDC score, or range of motion. Subgroup analysis demonstrated that for primary ACL reconstruction using the single-bundle technique, soft-tissue allografts were inferior to hamstring tendon autografts in subjective IKDC score, anterior drawer test, and side-to-side difference.

CONCLUSION

Soft-tissue allografts are inferior to hamstring tendon autografts with respect to subjective patient evaluation and knee stability but superior in the complication of hypoesthesia for patients undergoing primary ACL reconstruction.

Editorial Commentary: When Is Too Small, Too Small? Allograft Augmentation of Autologous Hamstring Grafts During Anterior Cruciate Ligament Reconstruction

Soft tissue allograft augmentation of small hamstring autografts, so-called hybrid grafts, has been proposed as an option during anterior cruciate ligament reconstruction (ACL-R). However, notable concerns exist with both small autograft use and allograft use during ACL-R, particularly in young, active patients. We currently choose to augment hamstring autografts with diameters <8.0 mm, adding only enough allograft to create a hybrid graft with an overall diameter no larger than 8.5 mm. Based on the available evidence, surgeons continue to seek the tipping point where the benefit of additional allograft tissue exceeds the consequence of its use.

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.

Risk of Infection After Allograft Anterior Cruciate Ligament Reconstruction: Are Nonprocessed Allografts More Likely to Get Infected? A Cohort Study of Over 10,000 Allografts

BACKGROUND

Allograft tissue is frequently used in anterior cruciate ligament reconstruction (ACLR). It is often irradiated and/or chemically processed to decrease the risk of disease transmission, but some tissue is aseptically harvested without further processing. Irradiated and chemically processed allograft tissue appears to have a higher risk of revision, but whether this processing decreases the risk of infection is not clear.

PURPOSE

To determine the incidence of deep surgical site infection after ACLR with allograft in a large community-based sample and to evaluate the association of allograft processing and the risk of deep infection.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

The authors conducted a cohort study using the Kaiser Permanente Anterior Cruciate Ligament Reconstruction Registry. Primary isolated unilateral ACLR with allograft were identified from February 1, 2005 to September 30, 2015. Ninety-day postoperative deep infections were identified via an electronic screening algorithm and then validated through chart review. Logistic regression was used to evaluate the likelihood of 90-day postoperative deep infection per allograft processing method: processed (graft treated chemically and/or irradiated) or nonprocessed (graft not irradiated or chemically processed).

RESULTS

Of 10,190 allograft cases, 8425 (82.7%) received a processed allograft, and 1765 (17.3%) received a nonprocessed allograft. There were 15 (0.15%) deep infections during the study period: 4 (26.7%) coagulase-negative Staphylococcus, 4 (26.7%) methicillin-sensitive Staphylococcus aureus, 1 (6.7%) Peptostreptococcus micros, and 6 (40.0%) with no growth. There was no difference in the likelihood for 90-day deep infection for processed versus nonprocessed allografts (odds ratio = 1.36, 95% CI = 0.31-6.04).

CONCLUSION

The overall incidence of deep infection after ACLR with allograft tissue was very low (0.15%), suggesting that the methods currently employed by tissue banks to minimize the risk of infection are effective. In this cohort, no difference in the likelihood of infection between processed and nonprocessed allografts could be identified.

Peak stresses shift from femoral tunnel aperture to tibial tunnel aperture in lateral tibial tunnel ACL reconstructions: a 3D graft-bending angle measurement and finite-element analysis

PURPOSE

To investigate the effect of tibial tunnel orientation on graft-bending angle and stress distribution in the ACL graft.

METHODS

Eight cadaveric knees were scanned in extension, 45°, 90°, and full flexion. 3D reconstructions with anatomically placed anterior cruciate ligament (ACL) grafts were constructed with Mimics 14.12^®. 3D graft-bending angles were measured for classic medial tibial tunnels (MTT) and lateral tibial tunnels (LTT) with different drill-guide angles (DGA) (45°, 55°, 65°, and 75°). A pivot shift was performed on 1 knee in a finite-element analysis. The peak stresses in the graft were calculated for eight different tibial tunnel orientations.

RESULTS

In a classic anatomical ACL repair, the largest graft-bending angle and peak stresses are seen at the femoral tunnel aperture. The use of a different DGA at the tibial side does not change the graft-bending angle at the femoral side or magnitude of peak stresses significantly. When using LTT, the largest graft-bending angles and peak stresses are seen at the tibial tunnel aperture.

CONCLUSION

In a classic anatomical ACL repair, peak stresses in the ACL graft are found at the femoral tunnel aperture. When an LTT is used, peak stresses are similar compared to classic ACL repairs, but the location of the peak stress will shift from the femoral tunnel aperture towards the tibial tunnel aperture.

CLINICAL RELEVANCE

the risk of graft rupture is similar for both MTTs and LTTs, but the location of graft rupture changes from the femoral tunnel aperture towards the tibial tunnel aperture, respectively.

LEVEL OF EVIDENCE

I.

Tibial tunnel enlargement and joint instability after anterior cruciate ligament reconstruction. A prospective comparison between autograft and allograft

PURPOSE

To investigate tibial tunnel widening and knee instability after ACL reconstruction with hamstring autograft or irradiated soft tissue allograft.

METHODS

Eight-two patients were divided into two groups: autograft group and allograft group. Radiographic and clinical evaluations were performed.

RESULTS

Seventy patients were followed up with median of 36.3 months (range 36-38 months). Tibial tunnel widening was at or greater than 30% for nine patients in the autograft group and 15 patients in the allograft group (P = 0.0417). The average percentage of tibial tunnel widening was 26.7 ± 4.0 % and 29.7 ± 5.3 % in autograft and allograft groups, respectively (P = 0.0090). Knee range of motion was not affected by the reconstruction operation or different grafts. Thigh atrophy improved significantly within 24 months after ACL reconstructions in both groups. ACL reconstruction with the allograft leaded to less knee stability than that with the autograft from one year after operation (P = 0.0023). There was no significant difference between two groups with respect to Lysholm score (P = 0.1925) and Tegner score (P =0 .0918) at the final follow-up.

CONCLUSION

The allograft group reported significantly more tibial tunnel widening and knee instability compared with the autograft group.

Anatomic Posterolateral Corner Reconstruction With Autografts

Anatomic posterolateral corner reconstruction reproduces 3 main structures: the lateral collateral ligament, the popliteofibular ligament, and the popliteus tendon. The LaPrade technique reproduces all 3 main stabilizers. However, it requires a long graft, limiting its indication to clinical settings in which allograft tissue is available. We propose a surgical procedure that is a modification of the LaPrade technique using the same tunnel placement, hamstring autografts, and biceps augmentation when necessary. It relies on artificial graft lengthening provided by the loop of the suspensory fixation device fixed at the anterior tibial cortex. The final reconstruction reproduces the popliteus tendon with the bulkiest end of the semitendinosus; the popliteofibular ligament with a strand of the semitendinosus and a strand of the gracilis; and the lateral collateral ligament with a strand of the semitendinosus and a strand of the gracilis, which can also be augmented with a biceps strip.