Second-Look Arthroscopic Evaluation and Clinical Outcomes of Anatomic Anterior Cruciate Ligament Reconstruction with Autograft and Hybrid Graft: A Retrospective Study

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.

Addition of the Sartorius Tendon Improves Biomechanics of a Four-Strand Hamstring Anterior Cruciate Ligament Autograft

PURPOSE

The purpose of this study was to quantify and compare the biomechanical properties and change in graft size when adding the sartorius tendon as a fifth strand to a four-strand ST-G hamstring autograft. Additionally, the sartorius tendon was tested individually to quantify its independent biomechanical properties.

METHODS

Four-strand and five-strand hamstring tendon grafts were harvested from matched cadaveric knees (mean age: 81.6 ± 9.8). These matched grafts were biomechanically tested using a MTS servohydraulic test system at a rate of testing representative of physiologic tears. The mean diameter, cross-sectional area, and ultimate load to failure were quantified and compared with a one-sided, paired Student's t-test. A P < .05 was considered statistically significant.

RESULTS

The mean diameter of the five-strand graft was significantly larger than the four-strand graft (9.30 ± .84 mm vs 8.10 ± .42 mm; P = .002). The average ultimate load to failure of the five-strand graft was 65.3% higher than the four-strand graft (2984.05 ± 1085.11 N vs. 1805.03 ± 557.69 N; P = .009) and added 14.8% to the diameter of the four strand ST-G autograft.

CONCLUSIONS

The addition of the sartorius tendon to a four-strand hamstring autograft significantly increased ultimate load to failure by 65%, graft cross-sectional area by 32%, and graft diameter by 15% compared to a traditional four-strand ST-G autograft. This information can be helpful to surgeons who wish to improve the strength of a four-strand ST-G autograft and for undersized grafts as an alternative to allograft supplementation.

CLINICAL RELEVANCE

The addition of the sartorius to the four-strand ST-G hamstring autograft significantly increases the ultimate load to failure and overall graft diameter, which can be particularly helpful in undersized autografts as an alternative to allograft supplementation.

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.

Small Size Autograft versus Large Size Allograft in Anterior Cruciate Ligament Reconstruction

Background

A small autograft diameter negatively affects functional outcomes, knee stability, and the risk of rerupture after anterior cruciate ligament (ACL) reconstruction, whereas the strength of allograft decreases over time. Therefore, it is not clear whether the use of smaller autografts or the use of larger allografts in ACL yields better results. The aim of this study was to compare the outcome of smaller autografts and larger allografts for ACL reconstruction.

Methods

Fifty-one patients who underwent ACL reconstruction with hamstring tendon autografts (size ≤ 8 mm) and 21 patients who underwent ACL reconstruction with allografts (size ≥ 10 mm) were included in our study. All patients underwent the same aggressive early postoperative rehabilitation program. There were no significant differences between the autograft and allograft groups regarding the preoperative patient age, sex, time from injury to surgery, and average follow-up time.

Results

The mean diameter of the 4-stranded hamstring tendon grafts used as autografts was 7.48 ± 0.33 mm and the mean diameter of the allografts was 10.76 ± 0.67 mm. According to specific tests for the ACL (anterior drawer, Lachman, and pivot shift) and clinical evaluation tests (Lysholm knee scoring scale and International Knee Documentation Committee questionnaire), the final follow-up results were significantly better than the preoperative status in both autograft and allograft ACL reconstruction groups. Therefore, there were no significant differences between the autograft and allograft groups preoperatively and at the final follow-up.

Conclusions

The large size of the graft in ACL reconstruction has been reported to affect results positively. However, in our study, we could not find any significant differences between the smaller size autografts and larger size allografts in terms of inadequacy, rerupture, and final follow-up functional results. Although allografts were significantly larger than autografts, we did not have the positive effect of larger size grafts. Smaller size autografts were as effective as the larger size allografts.

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.

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.

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.

Evaluation parameters of graft maturation on second-look arthroscopy following anterior cruciate ligament reconstruction: a systematic review

Purpose

The purpose of this systematic review was to investigate and summarize the evaluation methods of graft maturation on second-look arthroscopy following anterior cruciate ligament (ACL) reconstruction.

Methods

A literature search was performed on articles before December 2017 to identify the literature that has evaluated graft maturation on second-look arthroscopy following ACL reconstruction. Only studies using human grafts, evaluating graft maturation with two or more gross findings were included. Study design, grafts, surgical techniques, follow-up period, evaluation parameters, and categories were compiled.

Results

Twenty-eight studies were included in this study. All studies evaluated graft maturation with two or more of the following three findings: graft integrity, tension, and synovial coverage. Two to four categories were used for evaluating each parameter, but the criteria for classification were slightly different for each study. Several studies reported neo-vascularization of grafts and the total maturation score by summing up the scores assigned to each evaluation parameter. Three studies reported that there was no correlation between second-look findings and patient-reported outcomes.

Conclusions

Graft integrity, tension, and synovial coverage were the most frequently evaluated for graft maturation on second-look arthroscopy. However, there is no uniform criterion for evaluation. Therefore, development of a valid, uinform criterion is required.

Level of evidence

Level IV, systematic review of level I–IV investigations.

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.

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.

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.