Failure Rate and Clinical Outcomes of Anterior Cruciate Ligament Reconstruction Using Autograft Hamstring Versus a Hybrid Graft

Similarities in the kinematics of autografts and hybrid grafts for anterior cruciate ligament reconstruction: Minimum 2 years of follow-up

OBJECTIVE

To compare the clinical results of anterior cruciate ligament reconstruction (ACLR) with autografts and that with hybrid grafts of the same diameter.

METHODS

This study retrospectively included 102 patients who underwent ACLR from August 2017 to July 2019. According to graft type, the patients were divided into an autograft group (58 patients) and a hybrid graft group (44 patients). All grafts were 8.0 mm in diameter. The failure rate, knee kinematics with 6 degrees of freedom (DOFs), signal/noise quotient (SNQ), the Lachman test, pivot-shift test, Lysholm score, Tegner activity score, and International Knee Documentation Committee (IKDC) score were compared in each group after a minimum 2-year follow-up.

RESULTS

There was no significant difference in the failure rate between the autograft group (1.72%) and the hybrid graft group (2.27%) (P > 0.999). The SNQ values of the autograft group (16.42 ± 5.29 and 18.52 ± 5.30) at the middle and proximal sites were lower than those of the hybrid graft group (12.13 ± 5.62 and 16.35 ± 4.64; P = 0.020 and P < 0.001, respectively). In the autograft group, the results of range of motion at 6 DOFs and tibiofemoral kinematics at 5 DOFs (except internal-external rotation) were similar to those of the hybrid graft group (P > 0.05). The Lysholm score, Tegner activity score, IKDC score, Lachman test, and pivot-shift test showed no differences between the two groups (P > 0.05).

CONCLUSIONS

Autograft in ACLR has better graft maturity than hybrid grafts, but their kinematic characteristics are similar.

CLINICAL TRIAL REGISTRATION

ChiCTR2000037869.

Comparison of clinical outcomes between hamstring tendon autografts and hybrid grafts in ACL reconstruction: a systematic review and meta-analysis

BACKGROUND

Hamstring tendon (HT) autografts have become a popular choice for anterior cruciate ligament (ACL) reconstruction. However, small-diameter grafts are inevitably encountered during surgery, which have poor biomechanical properties. Hybrid grafts (HGs) using an allograft combined with small diameter HT are gaining interest from surgeons.

HYPOTHESIS

There would be no difference between the HT autograft and HG in terms of failure, knee stability, and patient-reported outcomes.

STUDY DESIGN

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

METHODS

The PubMed, Embase, web of science and Cochrane databases were systematically searched from their inception until July 1, 2022. Clinical trials that compared HG and HT autografts were included. The quality of the included studies was assessed with the Cochrane Collaboration's risk of bias tool and the modified Newcastle-Ottawa Scale. Extracted data were pooled with fixed or random effects depending on the detected heterogeneity.

RESULTS

A total of 14 eligible studies involving 1411 patients (HT: 863; HG: 548) were included in the quantitative meta-analysis. The mean age of the patients involved ranged from 14.6 to 40.4 years. Compared to patients who received HT autografts, patients receiving HGs had similar postoperative failure rate (OR, 0.99; P = 0.97; I2 = 41%), side-to-side difference (MD, -0.16; P = 0.13; I2 = 41%), Subjective IKDC (MD, 0.51; P = 0.58; I2 = 69%), Lysholm (MD, 2.79; P = 0.1; I2 = 79%), Tegner (MD, -0.88; P = 0.56; I2 = 0%). When the available data for failure rate were analyzed by the dose of irradiation, patient age, and mean diameter of the HT, the results of subgroup analyses did not change substantially.

CONCLUSION

This review found no significant differences in failure rates, knee stability, or patient-reported outcomes between autologous HT and HG in ACLR. Surgeons should prioritize autografts of adequate size through optimized techniques and consider hybrid grafts as a last resort, considering the risks associated with allografts.

Perioperative outcomes in isolated versus multiligamentous anterior cruciate ligament reconstruction: a retrospective cohort analysis

PURPOSE

The outcomes of anterior cruciate ligament reconstruction in the setting of multiligamentous knee injury (M-ACLR) have not been well characterized compared to isolated ACLR (I-ACLR). This study aims to characterize and compare short-term outcomes between I-ACLR and M-ACLR.

METHODS

This is a retrospective cohort analysis of the American College of Surgeons National Surgical Quality Improvement Program database from 2005 to 2017. Current Procedural Terminology codes were used to identify and compare elective I- and M-ACLR patients, excluding patients undergoing concomitant meniscal or chondral procedures. Patient demographics and outcomes after I- and M-ACLR were compared using bivariate analysis. Multiple logistic regression analyzed if multiligamentous ACLR was an independent risk factor for adverse outcomes.

RESULTS

There was a total of 13,131 ACLR cases, of which 341 were multiligamentous cases. The modified fragility index-5 was higher in multiligamentous ACLR (p < 0.001). Multiligamentous ACLR had worse perioperative outcomes, with higher rate of all complications (3.8%, p = 0.013), operative time > 1.5 h (p < 0.001), length of stay (LOS) ≥ 1 day (p < 0.001), wound complication (2.1%, p = 0.001), and intra- or post-op transfusions (p < 0.001). In multiple logistic regression, multiligamentous ACLR was an independent risk factor for LOS ≥ 1 (odds ratio [OR] 5.8), and intra-/post-op transfusion (OR 215.1) and wound complications (OR 2.4). M-ACLR was not an independent risk factor for any complication, reoperation at 30 days, readmission, urinary tract infection (UTI), or venous thromboembolism (VTE).

CONCLUSION

M-ACLR generally had worse outcomes than I-ACLR, including longer LOS, need for perioperative transfusions, and wound complications.

Comparison of failure rates and functional outcomes between hamstring autografts and hybrid grafts in anterior cruciate ligament reconstruction: A systematic review and meta-analysis

BACKGROUND

The viability of augmenting small-diameter hamstring autografts with allografts remains unclear. Recent studies have reported different clinical results after allograft augmentation. Hence, we sought to determine whether hamstring autografts and hybrid grafts differed in terms of failure rates and functional outcomes after anterior cruciate ligament (ACL) reconstruction. We also evaluated whether the results of the comparisons differed based on allograft sterilization methods.

PATIENTS AND METHODS

This systematic review and meta-analysis were performed by searching the PubMed, Cochrane Library, and EMBASE databases to identify prospective or retrospective studies (evidence levels 1, 2, or 3) that compared the failure rates and functional outcomes of ACL reconstruction using autografts and hybrid grafts.

RESULTS

We identified 15 relevant studies, including 1,521 patients, with 798 and 723 treated using autografts and hybrid grafts, respectively. Fourteen studies were retrospective comparative studies, and one was a prospective randomized controlled trial. Of these, three studies used non-irradiated allografts. In the analysis of all participants, no significant differences in failure rates and subjective International Knee Documentation Committee (IKDC) scores were observed between the autograft and hybrid graft groups. Comparing the autograft and hybrid graft groups that used non-irradiated allografts, no differences in the failure rates and subjective IKDC scores were also noted. Meanwhile, in the groups that used irradiated allograft, the autograft group demonstrated higher Lysholm knee scores and reduced anterior laxity than the hybrid graft group.

DISCUSSION

Overall, ACL reconstruction using hybrid grafts may not reduce failure rates compared to reconstructions using hamstring autografts, although hybrid grafts with irradiation may decrease functional outcomes.

LEVEL OF EVIDENCE

III; systematic review of level II and III studies.

No difference in revision risk between autologous hamstring graft less than 8 mm versus hybrid graft 8 mm or larger in anterior cruciate ligament reconstruction

PURPOSE

Hamstring autograft (HA) is commonly used for primary anterior cruciate ligament reconstruction (ACLR). However, if the harvested HA is inadequate in diameter, it is often augmented with an allograft tendon, forming a hybrid graft (HY). This study sought to evaluate aseptic revision risk following HA versus HY ACLR.

METHODS

A retrospective cohort study was performed using data obtained from our healthcare system's ACLR registry. Patients ≤ 25 years of age who underwent primary isolated ACLR were identified (2005-2020). Graft type and diameter size was the primary exposure of interest: < 8 mm HA and ≥ 8 mm HY. A secondary analysis was performed to examine 7 mm HA and 7.5 mm HA vs ≥ 8 mm HY. Propensity score-weighted Cox proportional hazard regression was used to evaluate the risk of aseptic revision.

RESULTS

The study sample included 1,945 ACLR: 548 ≥ 8 mm HY, 651 7 mm HA, and 672 7.5 mm HA. The crude cumulative aseptic revision probability at 8-years for ≥ 8 mm HY was 9.1%, 11.1% for 7 mm HA, and 11.2% for 7.5 mm HA. In adjusted analysis, no difference in revision risk was observed for < 8 mm HA (hazard ratio [HR] 1.15, 95% confidence interval [CI] 0.72-1.82), 7 mm HA (HR 1.23, 95% CI 0.71-2.11), or 7.5 mm HA (HR 1.16, 95% CI 0.74-1.82) compared to ≥ 8 mm HY.

CONCLUSION

In a US-based cohort of ACLR patients aged ≤ 25 years, we failed to observe any differences in aseptic revision risk for HA < 8 mm compared to HY ≥ 8 mm. Augmentation of a HA as small as 7 mm is not necessary to prevent a revision surgery.

LEVEL OF EVIDENCE

Level III.

Return to Sports: A Risky Business? A Systematic Review with Meta-Analysis of Risk Factors for Graft Rupture Following ACL Reconstruction

BACKGROUND

The risk of sustaining a graft rupture after anterior cruciate ligament reconstruction (ACLR) is high. Contributing risk factors are, however, still not clearly identified.

OBJECTIVE

The aim of this systematic review was to identify and quantify risk factors for graft rupture after ACLR.

METHODS

A systematic review with meta-analysis (PROSPERO CRD42020140129) based on PRISMA guidelines was performed. MEDLINE, CINAHL and EMBASE were searched from inception to September 2021. Prospective and retrospective studies addressing risk factors for graft rupture after ACLR in males/females of all ages were considered. Meta-analyses using a random effect model (effect measure: odds ratio [OR] with 95% confidence interval [CI]) were performed. The GRADE tool was used to assess evidence quality.

RESULTS

Following full-text screening of 310 relevant papers, 117 were eventually included, incorporating up to 133,000 individuals in each meta-analysis. Higher Tegner activity level (≥ 7 vs < 7) at primary injury (OR 3.91, 95% CI 1.69-9.04), increased tibial slope (degrees) (OR 2.21, 95% CI 1.26-3.86), lower psychological readiness to return to sport (RTS) (OR 2.18, 95% CI 1.32-3.61), early surgery (< 12 vs ≥ 12 months) (OR 1.87, 95% CI 1.58-2.22), RTS (pre-injury level) (OR 1.87, 95% CI 1.21-2.91) and family history of ACL injury (OR 1.76, 95% CI 1.34-2.31) were all associated with increased odds of graft rupture. Higher age (OR 0.47, 95% CI 0.39-0.59), female sex (OR 0.88, 95% CI 0.79-0.98), fewer self-reported knee symptoms pre-reconstruction (OR 0.81, 95% CI 0.69-0.95) and concomitant cartilage injuries (OR 0.70, 95% CI 0.62-0.79) instead decreased the odds. Meta-analysis revealed no association between body mass index, smoking, joint laxity, RTS time, knee kinematics, muscle strength or hop performance and graft rupture.

CONCLUSION

Conspicuous risk factors for graft rupture were mainly sports and hereditary related. Few studies investigated function-related modifiable factors or included sports exposure data.

Journey around the Notch: A Systematic Review on the History of ACL Reconstruction in the United States

The evolution of anterior cruciate ligament (ACL) surgery, seemingly circular at times, informs and provides context for past and current controversies in ACL management. The purpose of this systematic review is to objectively summarize the historical course of ACL reconstruction and repair in the United States over the last 40 years. Femoral tunnel drilling and graft selection have evolved dramatically over the last few decades. An initial focus on restoring ACL anatomy was for a period sacrificed for decreased operative morbidity. However, recent developments in operative techniques aim to restore ACL anatomy while also achieving minimal operative morbidity. Despite this historically iterative process, there remains no perfect choice for the treatment of ACL tears. Continued research on ACL repair, anatomic graft placement, graft choice, and augmentation will help our patients over the next generation.

Anterior Cruciate Ligament Reconstruction with Hybrid Graft versus Autograft: A Systematic Review and Meta-Analysis

Background

The standard surgical treatment for ACL tear is ACL reconstruction. There is a debate of a choice between autograft or hybrid graft for treating ACL reconstruction. The purpose of this paper is to compare both case scenarios.

Methods

A lot of libraries were searched like PubMed, Cochrane, and EMBASE Library for clinical trials which were then compared and analyzed via meta-analysis. The systematic review and meta-analysis were performed as per PRISMA guidelines, and RevMan software was used to perform the meta-analysis.

Results

We analyzed 6 studies where patients of both autograft and hybrid graft were studied. The study outcomes, graft failures, graft diameters, reoperations, and so on were compared via forest plot and funnel plot. No significant difference was noted in both cases.

Conclusions

In this meta-analysis, the performance of both autograft and hybrid graft was similar. Though the diameters were larger in hybrid, other factors also had an influence like graft failures, reoperations, and age at reconstruction which must be further investigated in detail.

Intraoperative Conversion to Five-Strand Hamstring Autograft Configuration Significantly Increases Anterior Cruciate Ligament Graft Diameter Independent of Patient Characteristics

Intraoperative conversion of a four-strand hamstring autograft to a five-strand configuration during an anterior cruciate ligament (ACL) reconstruction has been reported. However, the expected change in graft size and the dependence on patient characteristics are currently not well described. The purpose of this study was to determine the effective change in hamstring graft diameter and reliance on patient characteristics when intraoperatively converting a four-strand hamstring autograft into a five-strand configuration during an ACL reconstruction. A prospective, paired cohort study design was used to measure individual hamstring autograft diameter intraoperatively using traditional four-strand configuration followed by a five-strand configuration. All hamstring tendons included were long enough to consider a five-strand configuration. Five-strand hamstring autograft increased graft diameter in all patients. Hamstring tendon graft diameter increased by an average of 0.99 mm (95% confidence interval [CI]: 0.84-1.11) in the five-strand configuration compared with the traditional four-strand configuration (mean: 7.8 mm). There was no significant difference in the average increase in graft diameter between males (1.04 mm) and females (0.92 mm) (p = 0.323). Eighty-three percent (95% CI: 57.8-95.6) of average graft diameters ≤ 8 mm in the four-strand configuration achieved an average graft diameter of >8 mm in the five-strand configuration, and 70% (95% CI: 35.4- 91.9) of four-strand configuration average diameters < 8 mm achieved an average graft diameter > 8.0 mm in the five-strand configuration. Five-strand hamstring autograft reliably increased intraoperative hamstring tendon autograft diameter, with an average of 1 mm, compared with traditional four-strand configuration. This increase in diameter is independent of sex and remained significant when controlling for age, laterality, body mass index, and semitendinosus length.

Autograft diameter in ACL reconstruction: size does matter

BACKGROUND

Anterior cruciate ligament injuries are commonly seen in orthopedic surgery practice. Although anterior cruciate ligament reconstruction (ACLR) has come a long way, the causes of failure have yet to be fully understood.

OBJECTIVE

The aim of this study was to investigate whether or not the intraoperative 4-strand hamstring autograft diameter does in fact influence the failure rates of ACLR.

METHODS

Retrospective intraoperative data were collected from ACLR patients from the only tertiary center available in Kuwait. Patients who underwent ACLR from 2012 to 2018 for isolated ACL injuries were included in this study, allowing for a 24 month follow-up period The cohorts were categorized into 3 groups: patients with graft size≤8mm, 2, patients with graft sizes≥8mm with 4-strands and patients with graft sizes≥8mm with 4-strands or more. ANOVA analysis was applied to address group differences between mean graft size and strand numbers and subsequently the failure rates for each group. In addition, the Mann-Whitney U test was used to investigate the relationship between revision and initial ACL graft size.

RESULTS

Out of the 711 out of 782 patients were included in this study. Only 42.6% of the patients did not need more than 4-strands to achieve an 8mm sized autograft. The patients who had autografts≤8mm in this study accounted for 17.1% of the population. About 7.2% of these patients required revision surgery. Patients with a 4-strand autograft size that was less than 8mm were 7.2 times more at risk for ACLR failure (RR=7.2, 95% CI: 6.02; 8.35, p=0.007).

CONCLUSIONS

There is a significant correlation between 4-strand autograft diameter size and the need for ACLR revision surgery.

LEVEL OF EVIDENCE

IV case series.

Early Outcomes of Adolescent ACL Reconstruction With Hybrid Hamstring Tendon Autograft-Allograft Versus Hamstring Tendon Autograft Alone

Background:

Small-diameter semitendinosus-gracilis tendon autografts may be encountered intraoperatively during anterior cruciate ligament reconstruction (ACLR); these have been shown to be at increased risk of graft rupture. One option that surgeons have pursued to reduce the theoretical failure rate of these smaller-diameter grafts is augmenting them with allograft material, thereby forming a larger-diameter hybrid autograft-allograft construct.

Purpose/Hypothesis:

The purpose of this study was to compare outcomes in adolescent athletes of primary ACLR using a hybrid autologous hamstring tendon and soft tissue allograft construct versus ACLR using small-diameter hamstring tendon autograft. The hypothesis was that the hybrid hamstring autograft-allograft construct would provide superior short-term results.

Study Design:

Cohort study; Level of evidence, 3.

Methods:

We performed a retrospective analysis of 47 patients aged between 12 and 20 years who underwent hybrid graft ACLR (mean diameter, 9.1 mm) at a single institution. Electronic medical records including clinic notes, radiographic images, operative notes, and pathology reports were reviewed for study analysis. A control group of 64 patients who underwent small-diameter hamstring reconstruction (mean diameter, 7.1 mm) without allograft supplementation was compiled. Corresponding clinical, radiographic, and surgical characteristics were collected for the control group to allow for comparative analysis.

Results:

Mean follow-up was 2.7 years for the hybrid cohort and 2.3 years for the control group. Despite a significantly larger mean graft diameter in the hybrid group as compared with the control group (P < .001), no significant difference in retear rate was seen between cohorts (hybrid, 9%; control, 13%; P = .554). Patients with hybrid anterior cruciate ligament constructs also underwent a comparable number of reoperations overall (P = .838). Functionally, all patients with adequate follow-up returned to sports, with no significant difference in time to return to sports between the groups (P = .213). Radiographically, hybrid graft constructs did not undergo a significantly larger degree of tunnel lysis (P = .126).

Conclusion:

A cohort of adolescents with hybrid anterior cruciate ligament grafts was shown to have retear rates and overall clinical results comparable with those of a control group that received small-diameter hamstring tendon autografts alone.

Allograft Augmentation of Hamstring Autograft in Anterior Cruciate Ligament Reconstruction Results in Equivalent Outcomes to Autograft Alone

PURPOSE

To examine allograft augmentation of undersized hamstring (HS) autograft tendons at the time of anterior cruciate ligament (ACL) reconstruction, compared with un-augmented autograft HS ACL reconstruction.

METHODS

Patients who underwent ACL reconstruction at our institution between 2005 and 2015 were reviewed. Inclusion criteria included patients who underwent (1) primary ACL reconstruction, (2) use of a hybrid HS autograft with allograft augmentation, and (3) had a minimum 2-year postoperative follow-up. Patients with revision ACL, multiligamentous injuries, all-epiphyseal fixation techniques, or additional procedures beyond chondroplasty or meniscal repair/debridement were excluded. Data collected included demographics, graft size, concomitant procedures, revision operation, revision ACL reconstruction, and patient-reported outcomes.

RESULTS

In total, 59 patients met criteria for inclusion into the hybrid group, and 80 patients were eligible for inclusion into the control group. The average age of the cohort was 22.9 (interquartile range Q1:17, Q3: 38.3), and 51.8% of the patients were female. Seven patients (11.9%) in the hybrid ACL group underwent revision ACL surgery versus 15 (18.8%) in the control group (P = .27). There was no difference in patient-reported outcomes between groups.

CONCLUSIONS

Augmenting an HS ACL autograft that is 8 mm or less with allograft tissue to increase the overall size of the ACL graft shows no difference in overall reoperation or revision of ACL failure. The hybrid autograft/allograft ACL reconstruction patients showed no clinically important difference between groups in patient-reported outcome measures.

LEVEL OF EVIDENCE

Level III, case-control comparative analysis.

Editorial Commentary: Anterior Cruciate Ligament Hamstring Autografts Should Be Avoided in Patients Younger Than 25 Years Old: Autograft-Allograft Hybrids Remain Controversial

Some studies have reported no difference between autograft and hybrid anterior cruciate ligament reconstructions. However, other studies have shown a significantly greater revision rate. Consequently, surgeons are reluctant to perform hybrid reconstructions in younger patients with diminutive hamstring autografts and have turned to other autograft graft sources (e.g., quadriceps tendon, patellar tendon). Until we can perform high-quality prospective studies that can definitively answer this question, we should consider avoiding autograft hamstring reconstructions in patients younger than 25 years old so that we are not faced with the dilemma of implanting an undersized autograft or a hybrid graft, as both may be at increased risk for failure.

An Autograft for Anterior Cruciate Ligament Reconstruction Results in Better Biomechanical Performance and Tendon-Bone Incorporation Than Does a Hybrid Graft in a Rat Model

BACKGROUND

The biomechanical and tendon-bone incorporation properties of allograft-augmented hybrid grafts for anterior cruciate ligament (ACL) reconstruction compared with traditional autografts are unknown.

HYPOTHESIS

Using an autograft for ACL reconstruction yields better results on biomechanical testing, radiographic analysis, and histological evaluation versus using a hybrid graft.

STUDY DESIGN

Controlled laboratory study.

METHODS

A total of 66 adult male Sprague Dawley rats underwent unilateral ACL reconstruction with an autograft (AT group; n = 33) or a hybrid graft (HB group; n = 33). The grafts used in both groups were harvested from the peroneus longus tendon and were fixed by suturing to the surrounding periosteum. Samples were harvested for biomechanical testing, micro-computed tomography (CT), and histological evaluation at 4, 8, and 12 weeks postoperatively. Bone tunnels on the femoral and tibial sides were divided into 3 subregions: intra-articular (IA), midtunnel (MT), and extra-articular (EA). A cylinder-like volume of interest in the bone tunnel and a tubular-like volume of interest around the bone tunnel were used to evaluate new bone formation and bone remodeling, respectively, via micro-CT.

RESULTS

In the AT group, there were significantly higher failure loads and stiffness at 8 weeks (failure load: 3.04 ± 0.40 vs 2.09 ± 0.54 N, respectively; P = .006) (stiffness: 3.43 ± 0.56 vs 1.75 ± 0.52 N/mm, respectively; P < .001) and 12 weeks (failure load: 9.10 ± 1.13 vs 7.14 ± 0.94 N, respectively; P = .008) (stiffness: 4.45 ± 0.75 vs 3.36 ± 0.29 N/mm, respectively; P = .008) than in the HB group. With regard to new bone formation in the bone tunnel, in the AT group, the bone volume/total volume (BV/TV) was significantly higher than in the HB group on the tibial side at 8 weeks (IA: 22.21 ± 4.98 vs 5.16 ± 3.98, respectively; P < .001) (EA: 19.66 ± 7.19 vs 10.85 ± 2.16, respectively; P = .030) and 12 weeks (IA: 30.50 ± 5.04 vs 17.11 ± 7.31, respectively; P = .010) (MT: 21.15 ± 2.58 vs 15.55 ± 4.48, respectively; P = .041) (EA: 20.75 ± 3.87 vs 10.64 ± 3.94, respectively; P = .003). With regard to bone remodeling around the tunnel, the BV/TV was also significantly higher on the tibial side at 8 weeks (MT: 33.17 ± 8.05 vs 15.21 ± 7.60, respectively; P = .007) (EA: 25.19 ± 6.38 vs 13.94 ± 7.10, respectively; P = .030) and 12 weeks (IA: 69.46 ± 4.45 vs 47.80 ± 6.16, respectively; P < .001) (MT: 33.15 ± 3.88 vs 13.76 ± 4.07, respectively; P < .001) in the AT group than in the HB group. Sharpey-like fibers had formed at 8 weeks in the AT group. A large number of fibroblasts withdrew at 12 weeks. In the AT group, the width of the interface was significantly narrower at 4 weeks (85.86 ± 17.49 vs 182.97 ± 14.35 μm, respectively; P < .001), 8 weeks (58.86 ± 10.99 vs 90.15 ± 11.53 μm, respectively; P = .002), and 12 weeks (42.70 ± 7.96 vs 67.29 ± 6.55 μm, respectively; P = .001) than in the HB group.

CONCLUSION

Using an autograft for ACL reconstruction may result in improved biomechanical properties and tendon-bone incorporation compared with a hybrid graft.

CLINICAL RELEVANCE

Augmenting small autografts with allograft tissue may result in decreased biomechanical performance and worse tendon-bone incorporation, increasing the risk of graft failure.

Comparing Hamstring Autograft With Hybrid Graft for Anterior Cruciate Ligament Reconstruction: A Systematic Review

PURPOSE

To systematically review the literature in an effort to compare the demographics and clinical outcomes of patients undergoing anterior cruciate ligament reconstruction (ACLR) with a hamstring tendon autograft (HT) versus an irradiated or nonirradiated hybrid autograft-allograft.

METHODS

A systematic review of the PubMed, Cochrane Library, and Embase databases was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. All English-language literature that reported general demographics and compared the clinical outcomes of patients undergoing primary ACLR with autograft versus hybrid graft (HG) with a minimum 2-year follow-up was reviewed by 2 independent reviewers. Search terms used were "anterior cruciate ligament" and "hybrid graft." Patients were assessed based on graft failure, anteroposterior laxity, and patient-reported outcomes (Knee Injury and Osteoarthritis Outcome Score, visual analog scale, Subjective International Knee Documentation Committee score, Lysholm, and Tegner scores). Study quality was evaluated with the Modified Coleman Methodology Score and ROBINS-I risk of bias tool.

RESULTS

Twelve studies (1 level II, 11 level III) met inclusion criteria (follow-up, 2.0-8.9 years), including 471 patients undergoing ACLR with an irradiated hybrid graft (IH), 89 patients with a nonirradiated hybrid graft, and 829 patients with HT. Graft diameter ranged from 7.5 to 10.0 mm and from 6.5 to 10.0 mm in HG and HT patients, respectively. Overall, graft failure ranged from 0% to 30.0% and from 0% to 28.3% in HG and HT patients, respectively (I² = 35.9%; 95% confidence interval 0%-74.8%). Among HG patients, graft failure ranged from 0%-30.0% and from 2.4%-4.2% in IH and nonirradiated hybrid graft groups, respectively (I² = 33.6%; 95% confidence interval, 0%-71.8%). Results for postoperative anteroposterior laxity and patient-reported outcomes were also inconsistent.

CONCLUSIONS

Patients undergoing ACLR with HT demonstrate inconsistent differences in clinical outcomes at midterm follow-up compared with IH patients.

LEVEL OF EVIDENCE

III, systematic review of level II and III studies.

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.

Hamstring Autograft Versus Hybrid Graft for Anterior Cruciate Ligament Reconstruction: A Systematic Review

BACKGROUND

Hamstring tendon autografts are commonly used for primary anterior cruciate ligament (ACL) reconstruction. Some patients have small hamstring tendons however, which may compromise the clinical outcome of the autograft. To solve this problem, many surgeons use hybrid grafting that involves augmentation of small hamstring autografts with allograft tissue.

PURPOSE/HYPOTHESIS

The purpose was to compare the clinical outcomes between primary ACL reconstructions performed with hamstring autografts and those performed with hybrid grafts in terms of patient-reported evaluation, failure rate, and knee stability. The hypothesis was that primary ACL reconstruction performed with hamstring autograft alone will not differ significantly from that performed with a hybrid graft in terms of patient-reported evaluation, failure rate, or knee stability.

STUDY DESIGN

Systematic review.

METHODS

A systematic review was performed to identify prospective and retrospective comparative studies and cohort studies (evidence levels 1-3) comparing outcomes of primary ACL reconstructions performed with hamstring autografting alone and hybrid grafting. Outcomes included patient-reported evaluation, failure rate, and knee stability.

RESULTS

Ten studies were included: 1 of level 2 and 9 of level 3. Collectively, they included 398 autografts and 341 hybrid grafts. Mean respective follow-up durations ranged from 24.0 to 69.6 months and from 24.0 to 70.8 months. Patient-reported evaluations, including Lysholm, Tegner, and subjective International Knee Documentation Committee scores, were reported in 8 of 10 studies. Failure rates were reported in all 10 studies. Results of knee stability examinations-including KT-1000 arthrometer measurements, the pivot-shift test, Lachman test, and overall International Knee Documentation Committee results-were reported in 4 of 10 studies. In this review, there were no statistically significant differences between autografts and hybrid grafts in terms of patient-reported evaluations, failure rates, or KT-1000 measurements.

CONCLUSION

In this systematic review, there was no significant difference in patient-reported evaluation or failure rate between primary ACL reconstructions performed with autografts alone and those performed with hybrid grafts. Whether there is a substantial difference in knee stability examination results between autografts and hybrid grafts remains unknown, given a relative lack of reports on knee stability.

Independent Suture Tape Reinforcement of Tripled Smaller-Diameter and Quadrupled Grafts for Anterior Cruciate Ligament Reconstruction With Tibial Screw Fixation: A Biomechanical Full Construct Model

PURPOSE

To compare the effect of independent suture tape reinforcement on the dynamic elongation and stiffness behavior as well as ultimate strength of tripled smaller-diameter and quadrupled soft-tissue grafts for anterior cruciate ligament reconstruction (ACLR) with tibial screw fixation in a biomechanical in vitro study.

METHODS

Tripled smaller-diameter (8 mm) and quadrupled (9 mm) bovine tendon grafts with and without suture tape reinforcement (n = 8 in each group) were tested using femoral suspensory and tibial interference screw fixation. The suture tape was femoral sided and fixed independent from the graft by passing it through the suspensory button and securing the 2 open tibial strands with a secondary interference screw. Dynamic testing was performed in position and force control at 250 N and 400 N, followed by pull to failure with the mode of failure noted. Dynamic elongation, stiffness, and ultimate strength were analyzed.

RESULTS

Tripled constructs showed a significantly worse structural performance than quadrupled constructs at higher loads. Reinforcement of tripled and quadrupled grafts substantially decreased total elongation by 56% (4.54 ± 0.75 mm vs 2.01 ± 0.50 mm, P < .001) and 39% (3.25 ± 0.49 mm vs 1.98 ± 0.51 mm, P < .001), respectively, by significantly increasing dynamic stiffness. No statistical significance was found between the reinforced groups. Failure loads of reinforced tripled (1,074 ± 148 N vs 829 ± 100 N, P = .003) and quadrupled (1,125 ± 157 N vs 939 ± 76 N, P = .023) grafts were also significantly improved.

CONCLUSIONS

Independent reinforcement of soft-tissue grafts with suture tape strengthened the performance especially of tripled smaller-diameter grafts for ACLR with tibial screw fixation by significantly improving dynamic elongation at increased stiffness and ultimate strength. Quadrupled reinforced grafts showed no over-constraining and structurally behaved similarly to tripled grafts with reinforcement.

CLINICAL RELEVANCE

Independent reinforcement for ACLR may provide an option for protecting autografts or allografts against irreversible lengthening during the maturation and remodeling phases of healing.

Clinical outcomes and second-look arthroscopic findings of anterior cruciate ligament reconstruction with autograft, hybrid graft, and allograft

Background

There is no consensus as to the choice of grafts for primary anterior cruciate ligament (ACL) reconstruction. The purpose of this study was to compare the clinical and second-look arthroscopic outcomes after ACL reconstruction by use of autograft, hybrid graft, and γ-irradiated allograft.

Methods

Ninety-seven patients who underwent second-look arthroscopy after ACL reconstruction with autografts (28 patients, hamstring autograft), hybrid grafts (32 patients, hamstring autograft augmented with γ-irradiated tibialis anterior tendon allograft), or γ-irradiated allografts (37 patients, tibialis anterior tendons) were included in this study. The clinical outcomes were compared by using Lysholm score, International Knee Documentation Committee (IKDC) score, and Tegner activity score, and the side-to-side differences of KT-1000 measurement. Second-look arthroscopic findings were compared in terms of synovial coverage and graft tension.

Results

There were no statistical significances among the three groups in Lysholm score, IKDC score, or Tegner activity score (P > 0.05). The KT-1000 examination showed more anterior laxity in the γ-irradiated allograft group than in the autograft or hybrid graft groups (P = 0.006, and P = 0.013, respectively). Two patients in the autograft group, 2 patients in the hybrid graft group and 4 patients in the allograft group were evaluated as graft failure on second-look arthroscopy. The synovial coverage was superior in the autograft group than that in the hybrid graft group or the allograft group (P = 0.013 and P = 0.010, respectively), and was comparable between the hybrid graft group and allograft group (P = 0.876). With regard to graft tension, the autograft group and hybrid group were comparable (P = 0.883) but showed better results than the allograft group (P = 0.011 and P = 0.007, respectively).

Conclusion

The hamstring autografts and hybrid grafts used for ACL reconstruction produced equal efficacy but provided better knee stability than allografts. In addition, the hamstring autografts showed better synovial coverage than the other two graft types.

Small hamstring autograft is defined by a cut-off diameter of 7 mm and not recommended with allograft augmentation in single-bundle ACL reconstruction

PURPOSE

The present study was to analyze graft failure rates of hamstring tendon (HT) autografts with a cut-off graft diameter of 8 mm or 7 mm, and compare clinical outcomes between augmented small HT with an allograft and non-augmented relatively large HT in single-bundle anterior cruciate ligament reconstruction (ACLR).

METHODS

A literature search of PubMed, EMBASE, and the Cochrane Library was performed based on the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-analysis) guidelines. Studies to assess graft failure of autologous HT ACLR were reviewed, and graft failure rates with a cut-off graft diameter of 8 mm or 7 mm were further extracted. Clinical comparative studies of ACLR between augmented small HT with an allograft and non-augmented relatively large HT autografts were also included. Results are presented as risk ratio (RR) for binary data and weighted mean difference for continuous data with 95% confidence intervals (CI).

RESULTS

Nine studies with 2243 knees were included. Four studies examined the effect of HT autograft diameter on graft failure and five studies assessed clinical outcomes of allograft augmentation to small HT autografts. No significant difference was noted in graft failure with a cut-off diameter of 8 mm. No significant difference was found between diameters > 7 and ≤ 7 mm, but a significant difference was observed between diameters ≥ 7 and < 7 mm (RR = 0.49; 95% CI 0.26-0.92, I² = 0%, P = 0.03). A trend towards increased risk of graft failure was noted for allograft-augmented HT compared with non-augmented HT autografts (RR = 0.43; 95% CI 0.18-1.02, I² = 0%), but no significant differences were noted in IKDC, Lysholm, and Tegner scores between these groups.

CONCLUSION

The present study did support the use of 7 mm as a reference for cut-off diameter for small HT autografts, but not allograft augmentation to small HT autografts. These findings would guide clinical application of small HT autografts in single-bundle ACLR.

LEVEL OF EVIDENCE

IV.

Magnetic resonance imaging of the quadriceps tendon autograft in anterior cruciate ligament reconstruction

BACKGROUND

Quadriceps tendon (QT) autograft is emerging as a popular technique for primary anterior cruciate ligament (ACL) reconstruction. Studies have shown that it has comparable outcomes to bone-patellar tendon-bone (BPTB) and hamstring tendon (HT) autografts while mitigating post-operative complications associated with these grafts.

PURPOSE

To provide a literature summary of the important pre- and post-operative magnetic resonance imaging (MRI) findings of the quadriceps tendon and pertinent postoperative complications associated with the QT harvest. Radiologists should be familiar with MR findings after autologous graft harvest of the quadriceps tendon for reconstruction of the ACL.

LEVEL OF EVIDENCE

Level IV.

Editorial Commentary: The Trend to Blend: Should We Be Using Hybrid Grafts in Adult Anterior Cruciate Ligament Reconstructions?

Hybrid anterior cruciate ligament grafts augmenting a small-diameter hamstring tendon autograft with nonirradiated allografts can be used with good results in adults. In teens, however, outcomes of hybrid grafts have not been well defined, and other solutions to small hamstring grafts including graft folding, contralateral autograft augmentation, or selection of a different autograft source could be considered.

Hamstring Autograft Versus Hybrid Graft in Anterior Cruciate Ligament Reconstruction: A Systematic Review of Comparative Studies

PURPOSE

To compare (1) patient-reported outcomes, (2) objective knee measures of stability, (3) failures, and (4) reoperations after primary anterior cruciate ligament (ACL) reconstruction with semitendinosus-gracilis autograft versus autograft-allograft hybrid grafts.

METHODS

We performed a systematic review using Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Multiple databases were searched for studies that compared outcomes of ACL reconstruction with semitendinosus-gracilis autograft versus autograft-allograft hybrid grafts in adult human patients with minimum 2-year follow-up. Knee-specific patient-reported outcome scores, objective knee measures of stability, failures, and reoperations were reported for each study and compared between semitendinosus-gracilis autografts and hybrid grafts. Study heterogeneity and levels of evidence precluded meta-analysis.

RESULTS

We analyzed 6 articles (544 patients; 54.5% male patients; mean age, 30.9 ± 3.9 years; mean follow-up period, 43.6 ± 15.5 months). Of 6 studies, 4 showed no significant differences in International Knee Documentation Committee and Lysholm scores between the semitendinosus-gracilis autograft and hybrid groups. Five of six studies showed no significant differences in KT-1000 measurements between groups. The risk of ACL failure ranged from 3.2% to 8.4% for semitendinosus-gracilis autografts and from 2.4% to 14.3% for hybrid grafts, with no study reporting a significant difference in failure rates between groups. The reoperation rate in the subjects undergoing ACL reconstruction with semitendinosus-gracilis autografts and hybrid grafts ranged from 2.8% to 10.3% and from 2.4% to 48.3%, respectively. In 5 of 6 studies, no significant differences in reoperation rates were found between groups.

CONCLUSIONS

Most studies reported no significant differences in patient-reported outcome scores, objective knee measures of stability, and reoperation rates between semitendinosus-gracilis autografts and hybrid grafts. No significant difference in ACL failure rates was found between groups in any study.

LEVEL OF EVIDENCE

Level III, systematic review of Level II and III studies.

Allograft Augmentation of Hamstring Anterior Cruciate Ligament Autografts Is Associated With Increased Graft Failure in Children and Adolescents

BACKGROUND

Anterior cruciate ligament (ACL) reconstruction in adolescents is commonly performed with hamstring tendon autografts. Small graft diameter is one risk factor for graft failure and options to upsize the autologous hamstring graft include allograft augmentation and tripling one or both of the hamstring tendons.

PURPOSE

To evaluate the association of upsized hamstring graft constructs and graft rupture after ACL reconstruction.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

A retrospective review was performed of patients 19 years of age and younger who underwent hamstring autograft ACL reconstruction with or without soft tissue allograft augmentation from 2012 to 2016. All patients were skeletally mature or had less than 2 years of growth remaining. Graft constructs included 4-strand doubled semitendinosus and gracilis autograft (4-STG), 5-strand tripled semitendinosus and doubled gracilis autograft (5-STG), and 6-strand doubled gracilis and semitendinosus autograft augmented with a soft tissue allograft (6-STGAllo). The primary outcome measure was graft rupture.

RESULTS

A total of 354 patients with a mean age of 15.3 years (range, 10-19 years) were included. Graft constructs included 4-STG (198 knees), 5-STG (91 knees), and 6-STGAllo (65 knees). The average diameter of the graft constructs was 8.3 mm for 4-STG, 8.9 mm for 5-STG, and 9.2 mm for 6-STGAllo ( P < .001). The mean follow-up was 26 months (range, 6-56 months). There were 50 (14%) graft ruptures and 24 (7%) contralateral ACL tears. The graft failure rates were 14% for 4-STG, 12% for 5-STG, and 20% for 6-STGAllo ( P = .51). The average time to graft failure was 16 months (range, 2-40 months). After adjusting for age and graft size, patients who had allograft-augmented grafts (6-STGAllo) had 2.6 (95% CI, 1.02, 6.50) times the odds of graft rupture compared with 4-STG. There was no significant difference in failure rate between patients who had 5-STG grafts compared with 4-STG (OR, 1.2; 95% CI, 0.5, 2.7).

CONCLUSION

ACL reconstruction with hamstring tendon autografts augmented with allografts has a significantly increased risk of graft rupture compared with comparably sized hamstring tendon autografts. In situations where the surgeon harvests an inadequately sized 4-strand autograft, we recommend obtaining a larger graft diameter by tripling the semitendinosus rather than augmenting with an allograft.

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.

Hamstring Autograft Too Small: How Much Allograft Do You Need to Supplement to a Desired Hybrid Graft Size?

PURPOSE

To determine a simple rule for choosing supplemental allograft size for hybrid anterior cruciate ligament reconstruction using mathematical and cadaveric models.

METHODS

Mathematical and cadaveric models were used to determine the rule. The mathematical model required application of the geometric Pythagorean theorem to add areas of circles. Cadaveric semitendinosus and gracilis tendons were combined in multiple quadrupled hamstring size combinations and then sized using standard surgical techniques to confirm the mathematical model.

RESULTS

Geometric measurement, not simple addition, of graft diameters was required to determine the final graft size. Direct comparison of cadaveric and mathematical models showed close relations. If a final graft size of 7 mm is desired, an added diameter of all grafts of approximately 9.5 mm is needed. If a final graft size of 8 mm is desired, an added diameter of all grafts of approximately 11 mm is needed. If a final graft size of 9 mm is desired, an added diameter of all grafts of approximately 12.5 mm is needed. If a final graft size of 10 mm is desired, an added graft diameter of approximately 14 mm is needed. Cadaveric hamstring measurements were similar to the mathematical model.

CONCLUSIONS

By use of mathematical and cadaveric models, simple rules for determining the additional size of allograft diameter needed to supplement undersized hamstring autograft were created.

CLINICAL RELEVANCE

With the increasing availability of allograft types and sizes, surgeons currently have no guidelines on the size of allograft that is required to supplement an undersized hamstring autograft. Simple rules were created for determining the amount of allograft supplementation required for undersized hamstrings and are easily applied to clinical situations.

Editorial Commentary: Built to Last or Just a Trend? Hybrid Graft for Anterior Cruciate Ligament Reconstruction

The use of a hybrid autograft-allograft for primary anterior cruciate ligament reconstruction (ACLR) has gained significant attention in the orthopaedic sports medicine community in recent years. A hybrid graft is most often used to supplement a hamstring autograft with a small diameter, based on evidence that a graft size under a certain diameter (most often 8 mm) increases the risk for graft failure in younger patients. Multiple studies have been published comparing clinical outcomes of ACLR using a hybrid graft versus a hamstring autograft, with conflicting results. Although it is important to attempt to harvest a graft of sufficient size for this procedure, the indications for the use of a hybrid graft for primary ACLR are still unknown.

Risk of Retear Following Anterior Cruciate Ligament Reconstruction Using a Hybrid Graft of Autograft Augmented With Allograft Tissue: A Systematic Review and Meta-analysis

PURPOSE

To compare the risk of anterior cruciate ligament reconstruction failure in patients who undergo anterior cruciate ligament reconstruction with either autograft tissue or hybrid grafts.

METHODS

A systematic search was performed on February 28, 2018, on PubMed, Scopus, Arthroscopy, and Cochrane Library. Included studies were clinical outcome studies of primary anterior cruciate ligament reconstructions that compared failure risk for hybrid grafts versus autografts. Baseline and outcomes data were extracted, and reporting quality was assessed via modified Coleman criteria. A random effects meta-analysis was conducted for both randomized and nonrandomized studies.

RESULTS

Nine studies were identified with a mean of 40.1 months of follow-up. The mean Coleman methodology score was 66.5 (standard deviation, 12.8). One randomized study (Level II evidence) was identified with no difference in failure rates (0% for both groups, 8-mm minimum graft diameter for all patients). Eight nonrandomized studies (all Level III evidence) were identified with no difference in failure risk for hybrid grafts versus autograft (pooled odds ratio, 1.29; 95% confidence interval, 0.57-2.92; P = .55; I2 = 34%). Mean graft diameters were significantly larger in hybrid groups (range, 8.5-9.9 mm) than in autograft groups (range, 6.4-8.8 mm) in nonrandomized studies (mean difference, 0.5-2.5 mm; P ≤ .003). There was no evidence of small study bias or bias owing to reporting quality, and adjustment for length of follow-up, mean patient age, percentage of male patients, year of publication, or reporting quality did not improve statistical heterogeneity.

CONCLUSIONS

Based on the current literature, although it may be theoretically detrimental to add allograft to a small-diameter autograft, it cannot be definitively shown based on the findings of this review with meta-analysis. Currently, it remains unclear that there is an advantage or disadvantage to hybridization of small autograft with allograft, although randomized studies of patients with small (<8-mm) autograft diameters are lacking.

LEVEL OF EVIDENCE

Level III, systematic review of Level II and III studies.

Editorial Commentary: Reduce the Failure Risk: A Challenge to Reduce the Risk of Using Hybrid Graft in Anterior Cruciate Ligament Reconstruction

Hybrid grafting (augmentation of small hamstring autografts with allograft tissue) is preferred by many surgeons for anterior cruciate ligament (ACL) reconstruction. Although a recent, well-conducted, systematic review reported no significant differences in failure risk between hybrid graft and autograft ACL reconstruction, a trend toward a greater failure risk using the hybrid graft existed in many of the included studies. Three potential causes of hybrid graft ACL reconstruction failure that are absent in autograft ACL reconstruction are different levels of graft revascularization and ligamentization, differences in the tendon-bone healing capacity between the allograft and autograft portions in the bone tunnel, and processing of the graft. Research advances in these areas will further reduce the failure risk of hybrid graft 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.

Comparison of Clinical Outcomes After Anterior Cruciate Ligament Reconstruction Using a Hybrid Graft Versus a Hamstring Autograft

PURPOSE

This study aimed to compare the clinical outcomes of patients who underwent anterior cruciate ligament (ACL) reconstruction with a hybrid graft versus an autograft after 3 years of follow-up.

METHODS

Among 57 patients with an ACL injury who underwent ACL reconstruction, 28 patients received a hybrid graft (gracilis and semitendinosus tendon autograft plus a soft tissue allograft) and 29 patients received an autograft (gracilis and semitendinosus tendon autograft). The 2 groups were compared after a minimum 3-year follow-up regarding International Knee Documentation Committee (IKDC) assessment of knee function and stability, pivot-shift test, Lachman test, and KT-1000 side-to-side differences. The patient-reported Tegner activity score, Lysholm score, and subjective IKDC score were also compared. Graft failures were identified by patient-reported outcomes, physical examinations, or magnetic resonance imaging, and were confirmed on second-look arthroscopy; failure rate was compared between groups.

RESULTS

At final follow-up, the 2 groups significantly differed in pivot-shift test result (P = .013) and Lachman test result (P = .027). The failure rate tended to be greater in the hybrid graft group (14.3%) than in the autograft group (3.4%) (P = .148). All 5 patients with failed graft reconstruction were revised after second-look arthroscopy. The KT-1000 side-to-side differences at final follow-up were significantly inferior in the hybrid graft group (3.5 ± 2.0) compared with the autograft group (2.5 ± 1.0, P = .024). The hybrid graft group also had a lower mean Lysholm score (P = .000) and subjective IKDC score (P = .006) than the autograft group. The mean Tegner activity score was 6.8 ± 0.8 in the hybrid graft group and 6.9 ± 0.6 in the autograft group (P = .436).

CONCLUSIONS

The knee stability and patient-reported scores in the autograft-irradiated allograft hybrid graft ACL reconstruction group were significantly inferior compared with those in the autograft ACL reconstruction group.

LEVEL OF EVIDENCE

Level III, retrospective comparative study.

A Comparative Study of Clinical Outcomes and Second-Look Arthroscopic Findings between Remnant-Preserving Tibialis Tendon Allograft and Hamstring Tendon Autograft in Anterior Cruciate Ligament Reconstruction: Matched-Pair Design

Background

This study aimed to compare stability, functional outcome, and second-look arthroscopic findings after anterior cruciate ligament reconstruction between remnant-preserving tibialis tendon allograft and remnant-sacrificing hamstring tendon autograft.

Methods

We matched two groups (remnant-preserving tibialis tendon allograft group and hamstring tendon autograft group) in terms of demographic characteristics, associated injury, and knee characteristics. Each group consisted of 25 patients.

Results

Operation time was longer in the remnant-preserving tibialis tendon allograft group, but there was no significant intergroup difference in stability, clinical outcome, and second-look arthroscopic findings.

Conclusions

When an autograft is not feasible in anterior cruciate ligament reconstruction, the remnant-preserving technique can produce comparable results in terms of restoration of function, stability of the knee, and degree of synovium coverage at second-look arthroscopy compared to remnant-sacrificing hamstring autograft.

Thirty-Year Experience With ACL Reconstruction Using Patellar Tendon: A Critical Evaluation of Revision and Reoperation

Background:

During the preoperative discussion prior to anterior cruciate ligament reconstruction (ACLR), patients are often interested in data regarding rates of revision reconstruction, reoperation, concomitant pathologic changes, and future contralateral ACL injury.

Purpose:

To analyze a single surgeon’s experience with primary and revision ACLR over a 30-year interval, focusing on incidence and risk factors for revision and reoperation.

Study Design:

Case series; Level of evidence, 4.

Methods:

Patients who underwent ACLR from 1986 to 2016 were identified from a prospectively maintained database. Covariates of interest included age, sex, time, and graft selection. Outcomes of interest included revision and reoperation rates.

Results:

A total of 2450 ACLRs (mean patient age, 29 years; 58% male) were reviewed. Among primary ACLRs performed (n = 2225), 68% entailed bone–patellar tendon–bone (BTB) autograft and 30% entailed BTB allograft. Patients undergoing ACLR with autograft and allograft had a mean age of 22 and 37 years, respectively. The rate of revision ACLR was 1.8% and 3.5% for primary and revision cases, respectively. An increased rate of revision was noted among females compared with males (2.6% vs 1.2%) and among allografts compared with autografts (2.7% vs 1.3%). Low-dose irradiation did not affect allograft revision rates. The nonrevision reoperation rate following primary ACLR was 12%. The nonrevision reoperation rate was lower among primary cases reconstructed with allograft than autograft (9% vs 13%). Seventeen percent of cases involved concomitant meniscal repair and, among these, 13% required revision meniscal surgery. The rate of contralateral ACLR was 5.3%

Conclusion:

This information is useful in the informed consent process, for perioperative decision making regarding graft choice, and for identifying patients who are at risk for injuring the uninvolved knee.

Editorial Commentary: The Jury Remains Out on Hybrid Autograft-Plus-Allograft for Diminutive Hamstring Anterior Cruciate Ligament Autografts

In a Level III, single center, retrospective, nonrandomized observational study, anterior cruciate ligament reconstruction revision rates and patient-reported outcomes were found to be similar at 2-year follow-up when using autograft hamstrings versus a hybrid graft (autograft and nonirradiated allograft), with both groups reporting low levels of revisions and excellent outcomes. Despite previous published data that were cause for concern, a study in this issue provides support for use of a hybrid graft technique when encountering the challenging situation of a diminutive hamstring autograft when performing anterior cruciate ligament reconstruction.