A systematic review of anterior cruciate ligament reconstruction with autograft compared with allograft

Allograft to bone-tunnel integration in a canine anterior cruciate ligament reconstruction model: a comparison study of allograft preparation methods

The procedure of anterior cruciate ligament (ACL) allograft preparation can be divided into fresh-frozen method (FF-allograft) or freeze-dried method (FD-allograft). This study aims to biomechanically and histologically compare the graft to bone tunnel integration between the two allografts. In-vitro results indicated that FF-allograft and FD-allograft showed excellent biocompatibility and biomechanics, while FD-allograft showed a denser collagen fiber arrangement than FF-allograft and autograft. Then, in-vivo preformation of the FF-allograft, FD-allograft, and autograft on bone tunnel integration was evaluated via a canine ACL reconstruction model. In-vivo results indicated that no signs of infection or osteoarthritis were shown in the femur-graft-tibia complexes, but more vascularity and synovitis formed around the implanted FF-allograft. Micro-computed tomography showed that peri-graft bone in the FF-allograft group was significantly increased and remodeled compared with the FD-allograft group; Histologically, the FF-allograft group exhibited similar graft-bone tunnel healing to the FD-allograft group. Tartrate-resistant acid phosphatase (TRAP) staining showed significantly more osteoclasts presented in the FD-allograft group compared to the FF-allograft group. Meanwhile, a significantly higher failure load was shown in the FF-allograft group when compared with the FD-allograft group (P < 0.05). In conclusion, the FF-allograft integrated more firmly into the bone tunnel than the FD-allograft when used in ACL reconstruction.

Comparative study of the outcomes of one-stage versus two-stage reconstruction of chronic multiligament knee injury

BACKGROUND

Multi-ligament knee injury (MLKI) is a complex orthopaedic knee problem, usually following traumatic knee dislocation. Surgical management is preferred and has resulted in better clinical outcomes. However, the optimal surgical treatment protocol is continuously evolving. This study aimed to compare the outcomes of one-stage versus two-stage reconstruction of MLKI.

MATERIALS AND METHODS

This retrospective comparative study was conducted between July 2020 and December 2023 at a government orthopaedic hospital in Nigeria. The inclusion criteria include males and females between 18 and 45 years of age who had one- or two staged knee reconstructions for MLKI and were followed up for a minimum of 12 months. The exclusion criteria were patients below 18 and above 45 years of age, those with previous knee surgery, those associated with femoral or tibia fractures, those with radiological evidence of osteoarthritis, and those with follow-ups less than 12 months. Clinical outcomes using the Lysholm scoring system and complication rate were recorded. The statistical analysis was performed using SPSS version 23.

RESULTS

Fifty-one patients (26 in the OS group and 25 in the TS group) were studied. There was a significant difference between the preoperative and postoperative Lysholm scores in the two groups (p = 0.86 and 0.57 for OS and TS, respectively). However, there was no significant difference between the postoperative Lysholm scores in the two groups (p = 0.918).

CONCLUSION

One-stage and two-stage reconstruction of chronic MLKI give similar excellent clinical outcomes.

Diagnosis and treatment of anterior cruciate ligament injuries: Consensus of Chinese experts part II: Graft selection and clinical outcome evaluation

Background

In the recent decade, there has been substantial progress in the technologies and philosophies associated with diagnosing and treating anterior cruciate ligament (ACL) injuries in China. The therapeutic efficacy of ACL reconstruction in re-establishing the stability of the knee joint has garnered widespread acknowledgment. However, the path toward standardizing diagnostic and treatment protocols remains to be further developed and refined.

Objective

In this context, the Chinese Association of Orthopaedic Surgeons (CAOS) and the Chinese Society of Sports Medicine (CSSM) collaboratively developed an expert consensus on diagnosing and treating ACL injury, aiming to enhance medical quality through refining professional standards.

Methods

The consensus drafting team invited experts across the Greater China region, including the mainland, Hong Kong, Macau, and Taiwan, to formulate and review the consensus using a modified Delphi method as a standardization approach. As members of the CSSM Lower Limb Study Group and the CAOS Arthroscopy and Sports Medicine Study Group, invited experts concentrated on two pivotal issues: "Graft Selection" and "Clinical Outcome Evaluation" during the second part of the consensus development.

Results

This focused discussion ultimately led to a strong consensus on nine specific consensus terms.

Conclusion

The consensus clearly states that ACL reconstruction has no definitive "gold standard" graft choice. Autografts have advantages in healing capability but are limited in availability and have potential donor site morbidities; allografts reduce surgical trauma but incur additional costs, and there are concerns about slow healing, quality control issues, and a higher failure rate in young athletes; synthetic ligaments allow for early rehabilitation and fast return to sport, but the surgery is technically demanding and incurs additional costs. When choosing a graft, one should comprehensively consider the graft's characteristics, the doctor's technical ability, and the patient's needs. When evaluating clinical outcomes, it is essential to ensure an adequate sample size and follow-up rate, and the research should include patient subjective scoring, joint function and stability, complications, surgical failure, and the return to sport results. Medium and long-term follow-ups should not overlook the assessment of knee osteoarthritis.

Patients' under 25 subjective readiness to return to sport after ACL reconstruction with bone-patellar-bone grafts: Autograft vs. allograft

Purpose

To assess the difference in perceived readiness to return to sport (RTS) within the first year postoperative period between individuals undergoing anterior cruciate ligament (ACL) reconstruction with bone-patellar tendon-bone (BTB) autografts or allografts.

Methods

This was a prospective cohort study of patients undergoing primary ACL reconstruction done either with BTB autograft or allograft from 2010 to 2018. Skeletally mature patients aged 14 to 25 were eligible for inclusion. Patients completed the Marx Activity Rating Scale (MARS) questionnaire postoperatively evaluating perceived ability to perform various activities to compare subjective ability to RTS. Those patients who were outside outlined cohort age, failed to complete a single post-operative survey, underwent revision procedures, or underwent simultaneous or staged additional ligament surgery were excluded.

Results

Fifty-nine patients (20.1 ± 3.19 years, 57.6 % Male) were included in the study. Sixteen patients underwent ACL reconstruction with allograft (19.8 ± 3.43 years) while 43 patients received autograft (20.2 ± 3.13). At 3 months autograft recipients reported higher perceived ability to cut (P = .003). At 6-months, allograft recipients reported higher perceived ability to run (P = .033), cut (P = .048), and decelerate (P = .008) as well as a higher overall perceived ability to RTS (P = .032). At all other times, there was no significant difference between cohorts' subjective readiness to perform activities.

Conclusion

The results of this study indicate that at times within the first year of recovery following ACL reconstruction, patients who receive allografts and autografts may have significantly different perceived ability to perform activities or RTS. However, while present at various times throughout the first year of recovery, any difference in perceived ability to perform activities or in overall RTS is no longer present at 12 months.

Level of evidence

Level II, Prospective cohort study.

Medial Ulnar Collateral Ligament Reconstruction With Allograft Provides Excellent Clinical Outcomes, High Rates of Return to Play, and a Low Incidence of Postoperative Complications: A Systematic Review

PURPOSE

To perform a systematic review evaluating clinical outcomes in patients undergoing medial ulnar collateral ligament reconstruction (MUCLR) with soft-tissue allograft.

METHODS

A systematic review of the literature was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. The primary outcomes evaluated were patient-reported outcome scores, return to play (RTP) rates, incidence of postoperative complications, and rates of graft rupture or mechanical failure.

RESULTS

The literature search identified 395 articles, and 5 studies met final inclusion criteria after full-text review. A total of 274 patients were analyzed in the included studies and follow-up ranged from 3.0 to 7.6 years. Two studies (number of patients = 141) reported outcomes exclusively of MUCLR with allograft, whereas 3 studies (number of patients = 133) reported outcomes in patients undergoing MUCLR with either allograft or autograft. Allograft sources included gracilis, semitendinosus, plantaris, peroneus longus, and palmaris longus. Level of patient athletic competition ranged from recreational athletes to the professional level; however, nonathletes in the setting of trauma were also included. The RTP rate after MUCLR with soft-tissue allograft was 95.3%, and 89.3% of patients returned to a similar or greater level of play postoperatively. The Timmerman-Andrews score was reported in 2 studies, and the means postoperatively ranged from 94.55 to 97. Postoperative complication rates were low (range, 0% to 20%), and there were no reported incidences of allograft rupture or mechanical failure.

CONCLUSIONS

Based on the available data, soft-tissue allograft for MUCLR in athletic patient populations provides excellent clinical outcomes, high rates of RTP, and low rates of postoperative complications and graft failure at short-term follow-up. There remains a lack of high-quality evidence directly comparing autograft versus allograft outcomes in elite overhead-throwing athletes to support allograft as an acceptable alternative for MUCLR in this patient population. LEVEL OF EVIDENCE: Level IV, systematic review of Level III-IV studies.

Plastic and elastic biomechanical properties of anterior cruciate ligament autografts

BACKGROUND

Anterior cruciate ligament (ACL) rupture is a common orthopedic injury, occurring in roughly 68.6 per 100,000 persons annually, with the primary treatment option being ACL reconstruction. However, debate remains about the appropriate graft type for restoring the native biomechanical properties of the knee. Furthermore, plastic graft elongation may promote increased knee laxity and instability without rupture. This study aims to investigate the plastic properties of common ACL-R graft options.

METHODS

Patellar tendon (PT), hamstring tendon (HT), and quadriceps tendon (QT) grafts were harvested from 11 cadaveric knees (6 male and 5 female) with a mean age of 71(range 55-81). All grafts were mechanically tested under uniaxial tension until failure to determine each graft's elastic and plastic biomechanical properties.

RESULTS

Mechanically, the QT graft was the weakest, exhibiting the lowest failure force and the lowest failure stress (QT < HT, p = 0.032). The PT was the stiffest of the grafts, having a significantly higher stiffness (PT > QT, p = 0.0002) and Young's modulus (PT > QT, p = 0.001; PT > HT, p = 0.041). The HT graft had the highest plastic elongation at 4.01 ± 1.32 mm (HT > PT, p = 0.002). The post-yield behavior of the HT tendon shows increased energy storage capabilities with the highest plastic energy storage (HT > QT, p = 0.012) and the highest toughness (HT > QT, p = 0.032).

CONCLUSION

Our study agrees with prior studies indicating that the failure load of all grafts is above the requirements for everyday activities. However, grafts may be susceptible to yielding before failure during daily activities. This may result in the eventual loss of functionality for the neo-ACL, resulting in increased knee laxity and instability.

The Value of Ultrasound Diagnostic Imaging of Anterior Crucial Ligament Tears Verified Using Experimental and Arthroscopic Investigations

This study investigates the potential of the ultrasound imaging technique in the assessment of Anterior Cruciate Ligament (ACL) pathologies by standardizing the examination process. We focused on four key ultrasound parameters: the inclination of the ACL; swelling or scarring at the ACL's proximal attachment to the lateral femoral condyle; swelling or scarring of the ACL/posterior cruciate ligament (PCL) compartment complex with accompanying morphological changes in the posterior joint capsule; and dynamic instability, categorized into three ranges-0-2 mm, 3-4 mm, and ≥5 mm. The study group consisted of 25 patients with an ACL injury and 25 controls. All four tested parameters were found more frequently in the study group compared to the control (p < 0.0001). Our findings suggest that this standardized approach significantly augments the diagnostic capabilities of ultrasound, complementing clinical evaluation and magnetic resonance imaging (MRI) findings. The meticulous assessment of these parameters proved crucial in identifying subtle ACL pathologies, which might otherwise be missed in conventional imaging modalities. Notably, the quantification of dynamic instability and the evaluation of morphological changes were instrumental in early detection of ACL injuries, thereby facilitating more precise and effective treatment planning. This study underscores the importance of a standardized ultrasound protocol in the accurate diagnosis and management of ACL injuries, proposing a more comprehensive diagnostic tool for clinicians in the field of sports medicine and orthopedics.

Healing of acute anterior cruciate ligament rupture on MRI and outcomes following non-surgical management with the Cross Bracing Protocol

OBJECTIVE

Investigate MRI evidence of anterior cruciate ligament (ACL) healing, patient-reported outcomes and knee laxity in patients with acute ACL rupture managed non-surgically with the Cross Bracing Protocol (CBP).

METHODS

Eighty consecutive patients within 4 weeks of ACL rupture were managed with CBP (knee immobilisation at 90° flexion in brace for 4 weeks, followed by progressive increases in range-of-motion until brace removal at 12 weeks, and physiotherapist-supervised goal-oriented rehabilitation). MRIs (3 months and 6 months) were graded using the ACL OsteoArthritis Score (ACLOAS) by three radiologists. Mann-Whitney U tests compared Lysholm Scale and ACL quality of life (ACLQOL) scores evaluated at median (IQR) of 12 months (7-16 months) post-injury, and χ2 tests compared knee laxity (3-month Lachman's test and 6-month Pivot-shift test), and return-to-sport at 12 months between groups (ACLOAS grades 0-1 (continuous±thickened ligament and/or high intraligamentous signal) versus ACLOAS grades 2-3 (continuous but thinned/elongated or complete discontinuity)).

RESULTS

Participants were aged 26±10 years at injury, 39% were female, 49% had concomitant meniscal injury. At 3 months, 90% (n=72) had evidence of ACL healing (ACLOAS grade 1: 50%; grade 2: 40%; grade 3: 10%). Participants with ACLOAS grade 1 reported better Lysholm Scale (median (IQR): 98 (94-100) vs 94 (85-100)) and ACLQOL (89 (76-96) vs 70 (64-82)) scores, compared with ACLOAS grades 2-3. More participants with ACLOAS grade 1 had normal 3-month knee laxity (100% vs 40%) and returned to pre-injury sport (92% vs 64%), compared with participants with an ACLOAS grades 2-3. Eleven patients (14%) re-injured their ACL.

CONCLUSION

After management of acute ACL rupture with the CBP, 90% of patients had evidence of healing on 3-month MRI (continuity of the ACL). More ACL healing on 3-month MRI was associated with better outcomes. Longer-term follow-up and clinical trials are needed to inform clinical practice.

Anterior Cruciate Ligament Reconstruction Using Autologous Hamstrings Augmented with Ligament Augmentation and Reconstruction Systems (LARS) or Synthetic Meshwork of LARS Compared with Four-Strand Hamstring Tendon Grafts Alone, a Prospective, Randomized Clinical Study with 2- to 8-Year Follow-Up

Purpose

To compare the long-term outcomes of anterior cruciate ligament (ACL) reconstruction using a four-strand hamstring tendon graft alone (hamstring group) or with synthetics (Ligament Augmentation and Reconstruction System, LARS group) or synthetic meshwork of LARS (meshwork group).

Methods

Patients who underwent ACL reconstruction using four-strand hamstring tendon grafts (hamstring group), autologous hamstrings augmented with the LARS (LARS group), or synthetic meshwork of LARS (meshwork group) were selected in this prospective randomized clinical study. Patient-reported outcome measures (PROMs) were obtained preoperatively; at 6, 12, and 18 months postoperatively; and at final follow-up between 3 and 8 years. Second-look arthroscopic findings were used to evaluate graft morphology based on graft tension, graft tear, and synovial coverage.

Results

A total of 141 consecutive patients underwent ACL reconstruction, 47 patients in each group, and 21 patients were lost to follow-up during the study period. At the 6-month follow-up, the IKDC scores and Lysholm scores were significantly better in the LARS group (P < 0.05). At the 6- and 12-month follow-ups, the KOS-ADLS, KOOS-activities of daily living and quality of life, NSARS scores, GRC scores, Tegner scores, and ACL-RSI scores were significantly better in the LARS group (P < 0.05). For the LARS group, hamstring group, and meshwork group, the cumulative failure rates were 8.5%, 12.8%, and 4.3%, respectively. Malposition of the femoral tunnel was significantly associated with cumulative failure (P < 0.05). There was no difference between the groups in other outcomes at any other time, including radiographic and arthroscopic outcomes.

Conclusions

ACL reconstruction using autologous hamstring augmented with LARS resulted in significantly better clinical scores with a faster return to sports and comparative side-to-side differences in graft laxity by 6 and 12 months follow-up. Despite these findings, no statistically significant differences were seen among the three patient groups in terms of objective outcomes and clinical scores at the 18-month, 3-year and 8-year follow-ups. Additionally, a malpositioned femoral tunnel was associated with graft failure.

Anatomy of the anterior cruciate ligament and the common autograft specimens for anterior cruciate ligament reconstruction

A thorough understanding of the anatomical properties of the native anterior cruciate ligament (ACL), as well as the native specimens that are most commonly considered as viable autograft choices for anterior cruciate ligament reconstruction (ACLR), is warranted for continuing to pursue the best-possible graft choice for patients undergoing ACLR. While a wide variety of graft choices remain available to the operating surgeon, choosing the correct graft choice remains a consideration and discussion with patients on the pros and cons of each option. This article combines a review of the current literature on the quantitative and qualitative anatomy of the native ACL and common autograft specimens with the expert consensus of the senior author on the surgically-pertinent anatomy of these structures. The purpose of this article is to review the anatomy pertaining to the native ACL, along with the distal anatomy of the hamstring tendons, patellar tendon and quadriceps tendon (QT). Multiple tendinous and ligamentous structures exist around the knee that serve as viable candidates for use as autologous grafts for ACLR, and the anatomy of these distal extents of these structures are discussed thoroughly, including bony attachments, quantitative and relational anatomy, cross sectional area, and histological features of these structures.

Biomechanical considerations for graft choice in anterior cruciate ligament reconstruction

Injury to the anterior cruciate ligament (ACL) of the knee is common and often requires surgical reconstruction. There are numerous graft options available to the operating surgeon, to each of which a growing body of dedicated literature exists. Each of these potential choices of ACL graft specimen has a distinctive set of biomechanical properties, clinical outcome profiles, and other special considerations (e.g., autograft versus allograft, harvest site factors, and operating time). The purpose of this review is to discuss the biomechanical characteristics of the native ACL alongside those of several of the most commonly used ACL graft specimens based on a current review of the biomechanical literature. In doing so, this review will also briefly discuss the biomechanical implications for allograft versus autograft usage and single-bundle versus double-bundle repair techniques. This review lists and discusses the stress, strain, stiffness, Young's modulus, and ultimate load to failure of the native ACL, several common autografts [patellar bone-tendon-bone (BTB), hamstring tendon (HT), and quadriceps tendon (QT)], and several common allografts. Given the important biomechanical role of the ACL in stabilizing the knee to translational and rotational forces, it is crucial that the operating surgeon make a decision on graft choice that is informed in the biomechanical implications of ACL graft selection.

The relationship between drop vertical jump action-observation brain activity and kinesiophobia after anterior cruciate ligament reconstruction: A cross-sectional fMRI study

BACKGROUND

Injury and reconstruction of anterior cruciate ligament (ACL) result in central nervous system alteration to control the muscles around the knee joint. Most individuals with ACL reconstruction (ACLR) experience kinesiophobia which can prevent them from returning to activity and is associated with negative outcomes after ACLR. However, it is unknown if kinesiophobia alters brain activity after ACL injury.

OBJECTIVES

To compare brain activity between an ACLR group and matched uninjured controls during an action-observation drop vertical jump (AO-DVJ) paradigm and to explore the association between kinesiophobia and brain activity in the ACLR group.

METHODS

This cross-sectional study enrolled 26 individuals, 13 with ACLR (5 males and 8 females, 20.62 ± 1.93 years, 1.71 ± 0.1 m, 68.42 ± 14.75 kg) and 13 matched uninjured controls (5 males and 8 females, 22.92 ± 3.17 years, 1.74 ± 0.10 m, 70.48 ± 15.38 kg). Individuals were matched on sex and activity level. Participants completed the Tampa Scale of Kinesiophobia-11 (TSK-11) to evaluate the level of movement-related fear. To assay the brain activity associated with a functional movement, the current study employed an action-observation/motor imagery paradigm during functional magnetic resonance imaging (fMRI).

RESULTS

The ACLR group had lower brain activity in the right ventrolateral prefrontal cortex relative to the uninjured control group. Brain activity of the left cerebellum Crus I and Crus II, the right cerebellum lobule IX, amygdala, middle temporal gyrus, and temporal pole were positively correlated with TSK-11 scores in the ACLR group.

CONCLUSION

Brain activity for the AO-DVJ paradigm was different between the ACLR group and uninjured controls. Secondly, in participants with ACLR, there was a positive relationship between TSK-11 scores and activity in brain areas engaged in fear and cognitive processes during the AO-DVJ paradigm.

Single-stage versus two-stage reconstruction in chronic multi ligament knee injury

BACKGROUND

Multi ligament knee injury (MLKI) refers to the disruption of at least 2 of the 4 major knee ligaments. These injuries are managed in single and two-stage surgeries however, treatment guidelines for best practice are unsettled. There is no study in the literature that compares single and two-stage surgery for the management of chronic multiligament knee injury. Therefore, the aim of this study was to compare the functional outcome between single-stage and two-stage surgical fixation in chronic multi-ligament knee injury.

METHODS

Twenty seven patients with chronic MLKI with at least 2 years of follow up were included. Fourteen patients underwent reconstruction of torn ligaments in a single-stage operation (Group I) and 13 patients underwent reconstruction of torn ligaments in two stages (Group II). Assessment of clinical outcome was done with IKDC knee score, TEGNER LYSHOLM knee score, range of movement and laxity tests (Anterior drawer test, Lachman, Posterior drawer test, pivot shift test, dial test, varus and valgus stress test).

RESULTS

At final follow up, there was no significant difference in post-operative IKDC knee scores in group I and group II (84.7±7.1 and 81.4±8.4 respectively, p=0.3) and Lysholm scores (85.8±8.3 and 80.9±8.3 respectively, p=0.1), range of movement (133.2±5.7 and 131.5±6.6 respectively, p=0.5) and all the patients regained full extension. At the final follow up 12/14 patients (85.7%) in group I and 11/13 patients (84.6%) in group II had a negative/grade 1 anterior drawer test (p=0.6), 14/14 (100%) in group I and 13/13 (100%) patients had negative/grade 1 lachman test (p=0.6), 13/14 patients (92.8%) in group I and 13/13 patients (100%) patients in group II had negative/grade 1 pivot shift test (p=0.4), 9/10 patients (90%) in group I and 12/13 patients (92.3%) in group II had negative/grade 1 posterior drawer (p=0.6), 6/6 patients (100%) in group I and 6/7 patients (85.7%) in group II had negative/grade 1 dial test (p=0.3), 5/6 patients (83.3%) in group I and 5/7 patients (71.4%) in group II had negative/grade 1 varus stress test (p=0.4), 6/7 patients (85.7%) in group I and 7/7 patients (100%) in group II had negative/grade 1 valgus stress test (p=0.1).

CONCLUSION

Chronic MLKI managed by single stage and two stage reconstruction provides similar functional outcomes.

LEVEL OF EVIDENCE

Level III Retrospective Cohort Study.

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

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

Biomimetic Biphasic Electrospun Scaffold for Anterior Cruciate Ligament Tissue Engineering

BACKGROUND

Replacing damaged anterior cruciate ligaments (ACLs) with tissue-engineered artificial ligaments is challenging because ligament scaffolds must have a multiregional structure that can guide stem cell differentiation. Here, we designed a biphasic scaffold and evaluated its effect on human marrow mesenchymal stem cells (MSCs) under dynamic culture conditions as well as rat ACL reconstruction model in vivo.

METHODS

We designed a novel dual-phase electrospinning strategy wherein the scaffolds comprised randomly arranged phases at the two ends and an aligned phase in the middle. The morphological, mechanical properties and scaffold degradation were investigated. MSCs proliferation, adhesion, morphology and fibroblast markers were evaluated under dynamic culturing. This scaffold were tested if they could induce ligament formation using a rodent model in vivo.

RESULTS

Compared with other materials, poly(D,L-lactide-co-glycolide)/poly(ε-caprolactone) (PLGA/PCL) with mass ratio of 1:5 showed appropriate mechanical properties and biodegradability that matched ACLs. After 28 days of dynamic culturing, MSCs were fusiform oriented in the aligned phase and randomly arranged in a paving-stone-like morphology in the random phase. The increased expression of fibroblastic markers demonstrated that only the alignment of nanofibers worked with mechanical stimulation to promote effective fibroblast differentiation. This scaffold was a dense collagenous structure, and there was minimal difference in collagen direction in the orientation phase.

CONCLUSION

Dual-phase electrospun scaffolds had mechanical properties and degradability similar to those of ACLs. They promoted differences in the morphology of MSCs and induced fibroblast differentiation under dynamic culture conditions. Animal experiments showed that ligamentous tissue regenerated well and supported joint stability.

A Novel Approach to Augmenting Allograft Hamstring Anterior Cruciate Ligament Reconstructions Utilizing a Resorbable Type I Collagen Matrix with Platelet Rich Plasma

BACKGROUND

Anterior cruciate ligament reconstruction (ACLR) is one of the most common lower extremity orthopedic surgeries performed in the United States. Annually, between 100,000 and 200,000 ACL tears affect 1 in 3,000 people. The selection of autograft versus allograft for ACLR has been widely discussed in terms of risk of graft failure. Allograft reconstructions have been shown to have higher rerupture rates. One factor contributing to this risk is delayed biologic graft incorporation.

METHODS

A retrospective review was performed examining 14 patients who underwent an augmented quadruple-stranded hamstring allograft ACLR with a type I resorbable collagen matrix impregnated with platelet-rich plasma (PRP).

RESULTS

Within our clinical practice, the augmentation of quadruple-stranded hamstring allograft ACLR with a type I resorbable matrix impregnated with PRP has yielded good early clinical success at 2-year outcomes (N = 14). Zero ACLR failures have been reported to date in this series.

CONCLUSION

This case series offers a novel approach for soft tissue allograft ACLR augmented with a type I collagen matrix impregnated with PRP. The authors theorize that this augmentation may improve biologic graft incorporation into the host bone tunnels.

Outcomes of one-stage reconstruction for chronic multiligament injuries of knee

PURPOSE

This article aims to evaluate patterns of chronic multiligament injuries and outcomes of treatment with single-stage reconstruction using autografts.

METHODS

All patients with clinicoradiologically diagnosed multiligament knee injury (MKI) were included in this prospective observational study. As the time since injury was more than 6 weeks in all of the patients, they were categorized as having chronic MKI. Patients were assessed clinically for laxity, and the diagnosis was confirmed radiologically. Ipsilateral hamstring tendons were used for medial collateral ligament (MCL) or posterolateral corner reconstruction in a patient with Schenck knee dislocation (KD) type III. In these cases, the posterior cruciate ligament (PCL) and anterior cruciate ligament (ACL) were reconstructed by using the peroneus longus and contralateral hamstring tendons respectively. Ipsilateral hamstring tendons were used for ACL reconstruction and an ipsilateral peroneus longus tendon graft was used for reconstruction of the PCL in a KD type II injury. In two cases of KD type IV injury, the lateral laxity was only grade II and was managed conservatively; the rest of the ligaments were addressed like a KD type III injury. Outcome evaluation was done using a visual analogue scale (VAS) for pain, International Knee Documentation Committee (IKDC) score, Lysholm score, and Tegner activity level, preoperatively and postoperatively at 2 years' follow-up.

RESULTS

A total of 27 patients of mean age 33.48 ± 9.9 years with MKI were included in the study. The patients were classified as eight KD type II, 17 KD type III, and two KD type IV. The majority of the patients had associated meniscal (59.2%) or chondral (40.7%) injuries. At the 2 years' follow-up visit, there were significant improvements in VAS score (p = 0.0001) IKDC score (p = 0.0001), Lysholm score (p = 0.0001), and range of motion (p = 0.001). None of the patients had residual laxity on clinical examination of the knee joint at the 2 years' follow-up. All but two of the patients went back to their previous activity level. These two patients had progressive knee arthritis and needed knee arthroplasty.

CONCLUSION

Single-stage surgical reconstruction for chronic MKI has favourable functional outcomes.

LEVEL OF EVIDENCE

Level IV, case series.

Arthroscopy Primary Double-Bundle Repair of Anterior Cruciate Ligament With Internal Brace Augmentation and a Knotless Anchor Implant

The primary repair technique of acute anterior cruciate ligament (ACL) tears has been controversially discussed over the past few decades. Many different suture techniques have been reported for ACL repair, but these procedures showed high re-rupture rates and poor results. Recently, the literature has reported excellent outcomes with primary ACL repair. There has been a resurging interest in modernizing and augmenting primary ACL repair. This article describes a technique that uses internal brace augmentation and a knotless anchor (Arthrex) implant for primary anatomic double-bundle ACL repair after an acute proximal ACL tear. This technique aims to advocate natural healing by the high-strength internal brace augmentation and knotless anchor as a provisional scaffold during the healing phase and early mobilization. This technique might be an alternative to conventional ACL reconstruction in the appropriate selection of patients.

Biomechanical study of autograft anatomic reconstruction in lateral ankle instability

INTRODUCTION

The purpose of this work is perform a biomechanical comparison of anatomic reconstruction of the anterior talofibular ligament (ATFL) with the intact ATFL.

MATERIALS AND METHODS

We studied 18 fresh cadaveric ankles with intact ATFL. Each specimen was clinically assessed with the anterior drawer (AD) and varus tilt (VT) tests and the angular movement in the three spatial planes (axial, coronal and sagittal) was measured with an arthrometer using a sensor located in the talus.

RESULTS

Statistically significant differences were found in the axial plane, between the intact ATFL versus the sectioned ATFL for AD test with p = 0.012, and for VT test with p = 0.013. Regarding the coronal plane, we also observed a statistically significant difference for VT test with p = 0.016. In the sagittal plane, there are no statistically significant differences in both maneuvers. No statistically significant differences were found when comparing the biomechanics of anatomic ligament reconstruction versus the intact ATFL.

CONCLUSION

Autograft anatomic reconstruction of the ATFL showed biomechanical properties similar to those of the native ATFL, at the zero moment in a cadaveric model.

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.

Return to Play and Performance After Primary ACL Reconstruction in American Football Players: A Systematic Review

Background

Anterior cruciate ligament (ACL) injuries are among the most common sports-related injuries, and they can have a negative impact on players' ability to return to play (RTP). There is a paucity of literature focused on RTP after ACL reconstruction (ACLR) in collision sports.

Purpose

To characterize the impact that an ACL injury has on the ability to RTP and the post-ACLR performance level in American football players.

Study Design

Systematic review; Level of evidence, 4.

Methods

An electronic search was performed using the following databases: the Cochrane Database of Systematic Reviews, the Cochrane Central Register of Controlled Trials, PubMed, Embase, and the Cumulative Index to Nursing and Allied Health Literature. Included studies were written in English; were published since the year 2000; examined only American football players; and reported on RTP, performance, and/or career length after primary ACLR.

Results

The initial search yielded 442 unique studies. Of these, 427 were removed after screening, leaving 15 studies that met inclusion criteria. An additional 2 studies were identified in these studies' references, yielding a total of 17. The rate of RTP after ACLR for football players was 67.2% (1249/1859), and the mean time to return was 11.6 months (range, 35.8-55.8 weeks). Although considerable heterogeneity existed in the study design and outcomes measured, in general, a majority of football players experienced greater declines from their preinjury performance level than controls over the same time period.

Conclusion

An ACL injury negatively affected football players' ability to RTP and their post-ACLR performance. The degree of effect varied by several factors, including playing position, preinjury performance level, and National Football League Draft round. These results may be used by physicians and football players to develop reasonable expectations for returning to play and performance after an ACL injury.

Xenograft for anterior cruciate ligament reconstruction was associated with high graft processing infection

Purpose

To evaluate clinical ad radiological outcomes of anterior cruciate ligament (ACL) reconstruction with an immunochemically modified porcine patellar tendon xenograft controlled against human Achilles tendon allograft at 24-month minimum follow-up.

Methods

66 patients undergoing arthroscopic ACL reconstruction were randomized into 2 groups: 34 allografts and 32 xenografts treated to attenuate the host immune response. Follow-up was 24-month minimum. Anterior knee stability was measured as KT − 1000 side-to-side laxity difference (respect to the contralateral healthy knee). Functional performance was assessed by one-legged hop test. Objective manual pivot-shift test and subjective (IKDC, Tegner and SF-36) outcomes were collected. MRI and standard X-Ray were performed.

Results

61 subjects (32 allograft, 29 xenograft) were evaluated at 12 and 24 months. Six of the subjects in xenograft group (20.6%) got an infection attributed to a water-based pathogen graft contamination in processing.

Intention-to-treat analysis (using the last observation carried forward imputation method) revealed higher KT − 1000 laxity in xenograft group at 24-month follow-up (P = .042). Also pivot-shift was higher in xenograft group at 12-month (P = .015) and 24-month follow-up (P = .038).

Per-protocol analysis (missing/contaminated subjects excluded) did not revealed clinical differences between groups.

Tibial tunnel widening in the allograft group was low, whereas xenograft tunnel widening was within the expected range of 20–35% as reported in the literature.

No immunological reactivity was associated to xenograft group.

Conclusions

High infection rate (20.6%) was reported in xenograft group. Both groups of patients achieved comparable clinical outcomes if missing/contaminated subjects are excluded. Improved harvesting/processing treatments in future studies using xenografts for ACL reconstruction are needed to reduce infection rate, otherwise xenograft should not be used in ACL reconstruction.

Level of evidence

Multicenter and double-blinded Randomized Controlled Clinical Trial, Level I.

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

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

A Review on Finite Element Modeling and Simulation of the Anterior Cruciate Ligament Reconstruction

The anterior cruciate ligament (ACL) constitutes one of the most important stabilizing tissues of the knee joint whose rapture is very prevalent. ACL reconstruction (ACLR) from a graft is a surgery which yields the best outcome. Taking into account the complicated nature of this operation and the high cost of experiments, finite element (FE) simulations can become a valuable tool for evaluating the surgery in a pre-clinical setting. The present study summarizes, for the first time, the current advancement in ACLR in both clinical and computational level. It also emphasizes on the material modeling and properties of the most popular grafts as well as modeling of different surgery techniques. It can be concluded that more effort is needed to be put toward more realistic simulation of the surgery, including also the use of two bundles for graft representation, graft pretension and artificial grafts. Furthermore, muscles and synovial fluid need to be included, while patellofemoral joint is an important bone that is rarely used. More realistic models are also required for soft tissues, as most articles used isotropic linear elastic models and springs. In summary, accurate and realistic FE analysis in conjunction with multidisciplinary collaboration could contribute to ACLR improvement provided that several important aspects are carefully considered.

Return to sports following arthroscopic primary repair of the anterior cruciate ligament in the adult population

BACKGROUND

To assess return to sport (RTS) rates and evaluate the timeline of rehabilitation milestones following arthroscopic primary anterior cruciate ligament (ACL) repair.

METHODS

A retrospective review of all patients treated with primary repair between 2008 and 2018 was conducted. All adult patients with preoperative Tegner of ≥6 and minimum follow-up of two years were included. Patients were seen in clinic or contacted to complete the postoperative Tegner, and report their time to return to work, time to running, and time to RTS. Additionally, they were asked to complete the ACL-Return to Sport After Injury (ACL-RSI). Outcomes were compared using Mann-Whitney U tests and chi-square tests.

RESULTS

Sixty patients treated with repair were included, of which 85% returned to any sports, 70% returned to knee-strenuous sports, and 60% returned to preinjury level. Patients returned to work in seven days (IQR five to 14 days), running in 90 days (IQR 57-120 days), and sports in 180 days (IQR 116-270 days). Overall, ACL-RSI score was 80.0 (IQR 53.0-95.0). Higher return to preinjury rates was found in patients with older age and lower fear of reinjury (all p < .05).

CONCLUSION

Following primary ACL repair, 70% of adult patients returned to knee-strenuous sports and 60% to preinjury levels by 180 days postoperatively. Positive predictors for return to preinjury levels included older age and low fear of reinjury.

LEVEL OF EVIDENCE

Retrospective Case-Series, level IV.

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.

Patients Forget About Their Operated Knee More Following Arthroscopic Primary Repair of the Anterior Cruciate Ligament Than Following Reconstruction

PURPOSE

To assess the extent to which patients forget their operative knee joint on a daily basis following arthroscopic primary repair as compared with reconstruction of the anterior cruciate ligament (ACL) at short- to mid-term follow-up.

METHODS

For this retrospective study, all patients undergoing ACL surgery between May 2012 and May 2017 were identified. All patients were treated with the algorithm of undergoing arthroscopic primary repair for proximal tears and reconstruction for nonrepairable tears. Patients were contacted to complete the Forgotten Joint Score-12 questionnaire between 2 and 5 years following surgery. A greater score represents a more favorable outcome indicating the patient's ability to "forget" the joint in everyday life, whereas lower scores indicate a less-favorable outcome. Data were analyzed using independent t-tests and χ2 tests, and multiple linear regression analysis was performed to correct for potential confounders.

RESULTS

Eighty-three patients completed the questionnaire (57%). Patients who underwent primary repair thought about their operated knee less when compared with those patients who underwent reconstruction (85.3 ± 14.2 vs 74.3 ± 23.3, P = .022). These differences were significantly greater in patients older than 30 years (85.3 ± 12.9 vs 62.6 ± 24.9, P = .007), male patients (85.0 ± 13.6 vs 72.5 ± 24.7, P = .037), and patients with a body mass index greater than 25 (85.9 ± 14.5 vs 64.7 ± 25.6, P = .009). After we corrected for potential confounders, the overall difference remained significant (P = .045).

CONCLUSIONS

Based on the data in this study, patients undergoing arthroscopic primary ACL repair can expect to have less daily awareness of their operated knee at short- to mid-term follow-up as compared with patients undergoing ACL reconstruction.

LEVEL OF EVIDENCE

Retrospective comparative study, level III.

Arthroscopic Primary Repair of the Anterior Cruciate Ligament With Single-Bundle Graft Augmentation

Recently, there has been a resurgence of interest in ligament preservation of the anterior cruciate ligament (ACL) that has the advantage of preserving the native tissue and maintaining proprioceptive function. Studies reporting outcomes of remnant-preserving ACL surgery have shown encouraging results with a higher potential for early healing and better functional outcomes compared with remnant-resecting surgery. Over the past decade, several surgical techniques for remnant preservation of the ACL have been proposed. In this technical note, the technique of primary ACL repair with graft augmentation is described. The goal of this technique is to preserve and tension the native tissue, thereby restoring the anatomy as much as possible while avoiding cyclops lesions, whereas the additional graft provides strength to the repaired ligament.

Lateral ankle ligament anatomic reconstruction for chronic ankle instability: Allograft or autograft? A systematic review

BACKGROUND

To investigate if there is any evidence in favour of autograft or allograft use for anatomic reconstruction of lateral ankle ligaments in patients with symptomatic chronic ankle instability.

METHODS

A literature search was performed in PubMed MEDLINE, Cochrane Library, EMBASE and Google Scholar databases, over the years 1994-2017, to identify the studies presenting clinical results of anatomic lateral ankle ligaments reconstruction using various combinations of the keywords "lateral ankle ligaments reconstruction", "anatomic reconstruction", "chronic ankle instability", "allograft", "autograft". The surgical procedure was considered anatomic if consistent with the description of lateral ankle ligaments made by Burks and Morgan in 1994.

RESULTS

Among the 89 papers matching the search terms, only 12 could be included in which 357 anatomic lateral ankle ligaments reconstructions were performed. One was a comparative case series (level of evidence III - LOE III) while other papers were retrospective case series (LOE IV), the mean Modified Coleman Methodology Score (MCMS) was fair: 56.7 (SD±5.2). Due to the low level of evidence of the available literature only a qualitative analysis was performed. The limited evidence from the studies analysed suggests that there is no difference in graft survivorship, graft-dependent variables, patient's satisfaction, clinical outcome measures and radiographic results between allograft and autograft.

CONCLUSIONS

Given the low number of studies, their poor methodology score and their low level of evidence it is not possible to determine if allograft is better or safer than autograft.

LEVEL OF EVIDENCE

Level IV, review paper of level III and level IV studies.

Effects of Graft Selection in Arthroscopic Anterior Cruciate Ligament Reconstruction: Midterm Functional Results

Objectives:

This study is a comparison of the midterm clinical results of patients who underwent anterior cruciate ligament (ACL) reconstruction using an allograft and those who had an autograft procedure.

Methods:

The results of 70 patients who underwent ACL reconstruction with an anterior tibial tendon (ATT) allograft (n=18) or a hamstring (HT) autograft (n=52) were evaluated retrospectively. At the last follow-up, International Knee Documentation Committee (IKDC) and Tegner-Lysholm scores were used to assess functional status, as well as results of the Lachman test, the anterior drawer test, and the pivot-shift test.

Results:

There was no significant difference between the 2 groups in terms of age, gender, length of time before operation, graft thickness, or femoral tunnel length (p>0.05). The results were satisfactory in both groups in the postoperative period in terms of the length of time until a return to sports, IKDC score, Tegner-Lysholm score, range of motion, quadriceps circumference, and laxity, with no significant difference between the groups (p>0.05).

Conclusion:

The results of this study suggested that midterm clinical outcomes of ACL reconstruction with an ATT allograft or an HT autograft are similar when the correct technique is used according to the appropriate indications by an experienced surgeon and a successful rehabilitation program implemented after the operation.

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

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSION

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

LEVEL OF EVIDENCE

IV.

The use of allograft tendons in primary ACL reconstruction

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSION

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

LEVELS OF EVIDENCE

III.

Comparison of freeze-dried tibialis anterior allograft and four-strand hamstring autograft in anterior cruciate ligament reconstruction

PURPOSE

The aim of this retrospective study was to evaluate the clinical outcomes of the patients who underwent primary anterior cruciate ligament (ACL) reconstruction surgery with either hamstring autograft or freeze-dried tibialis anterior allograft, which performed by the same surgeon using the same fixation technique.

METHODS

In this retrospective study, patients who had primary ACL reconstruction using either four-strand hamstring autograft (FSH) or freeze-dried irradiated tibialis anterior allograft (FDT) between 2012 and 2015 were evaluated. Patients who were skeletally mature with a minimum follow-up of 24 months and who had no previous surgery from the affected knee were included; patients who had multiple ligament injuries or chondral lesions over Outerbridge grade 2 were excluded from the study. Patients were grouped according to the graft type used in ACL reconstruction. Tegner activity scale and Lysholm knee scoring scale were used to assess patients' activity levels and functional status preoperatively and at the final follow-up. KT-2000 arthrometer measurements were done at the final follow-up to evaluate anterior laxity.

RESULTS

There were 27 patients (mean age 27 ± 8.9 years) in the FSH group and 36 patients (mean age 27.1 ± 6.7 years) in the FDT group. The mean follow-up time was 38.2 ± 3.5 months for the FSH group and 41 ± 6.1 months for the FDT group. There were no statistically significant differences between the groups when preoperative and postoperative Tegner-Lysholm scores were compared (Tegner P = 0.583, 0.742; Lysholm P = 0.592, 0.249). The mean anteroposterior laxity and side-to-side differences measured by KT-2000 were 4.1 mm and 2.1 mm for the FSH group, respectively; 4.2 mm and 2.2 mm for the FDT group, respectively. There was not a statistically significant difference (P = 0.745, 0.562 respectively).

CONCLUSIONS

Primary ACL reconstruction with a single loop freeze-dried irradiated tibialis anterior allograft revealed comparable results with four-strand hamstring autograft in non-athlete patients.

LEVEL OF EVIDENCE

Level III, Therapeutic study.

The Surgical Applications of Biologics in Sports Medicine

Over the past 25 years an increased appreciation of the positive impact of biologic interventions has driven significant advances in the surgical treatment of shoulder and knee conditions. These biologic adjuncts to treatment promote improved outcomes and have set the stage and increased research and development in this arena.

Anterior cruciate ligament reconstruction with quadriceps tendon-patellar bone allograft: matched case control study

Background

Quadriceps tendon-patellar bone (QTPB) autograft is an excellent graft option with good clinical outcome. Use of QTPB autografts have increased because they minimize donor-site morbidity including anterior knee pain, while providing adequate mechanical strength. Although, there were many clinical results about allografts that used in anterior cruciate ligament (ACL) reconstruction, it have never been reported about the clinical outcome of ACL reconstruction with QTPB allograft.

The purpose of this study is to evaluate the clinical outcome of ACL reconstruction with QTPB allograft and to compare with QTPB autograft. We hypothesized that ACL reconstruction with QTPB allograft had good functional outcomes and stability and no significant difference compared to the ACL reconstruction with QTPB autograft.

Methods

From February 2009 to January 2014, 213 cases who received ACL reconstruction with QTPB grafts were included. Forty-five patients who received ACL reconstruction with QTPB allograft were individually matched in age, sex, direction of the injured knee and body mass index (BMI) to a control group of 45 patients who received QTPB autograft. Clinical results were evaluated using International Knee Documentation Committee (IKDC) score, Lysholm score, Tegner scale, Knee injury and Osteoarthritis Outcome Score (KOOS) and ligament laxity. An average follow-up time was 31.2 months.

Results

The functional scores and ligament laxity improved from initial to the last visit in those with ACL reconstruction with QTPB allograft (p < 0.05). No significant statistical difference was found in clinical outcomes and complications including re-rupture between the QTPB allograft and autograft groups (p > 0.05). Laxity using anterior drawer test, Lachman test and KT-2000 showed no significant difference. No significant difference was found between the two groups in quadriceps peak extension torque, except at 60° per second at 6 months.

Conclusion

QTPB allograft achieved good clinical outcome with no difference compared with QTPB autograft. QTPB allograft for ACL reconstruction is promising alternative to selected and compliant patients. Long-term follow-up needs to further evaluate the clinical outcomes and complications including re-rupture rate.

Clinical and magnetic resonance imaging assessment of anatomical lateral ankle ligament reconstruction: comparison of tendon allograft and autograft

PURPOSE

To compare the results of anatomical lateral ankle ligament (LAL) reconstruction with tendon allograft and autograft using clinical scores and ultrashort echo time (UTE) sequence of MRI.

METHODS

A total of 26 patients with LAL reconstruction were recruited in this study, including 16 using semitendinosus allografts and 10 using semitendinosus autograft. All of them were diagnosed as chronic ankle instability and accepted anatomic reconstruction. The American Orthopedic Foot and Ankle Society (AOFAS) score, Karlsson score, and radiological evaluation using MRI UTE scanning were extracted from each patient. The comparative analysis of the clinical assessments and UTE-T2* values were performed between the patients using autografts and allografts.

RESULTS

For the allograft group, the mean AOFAS score improved from 69.9 ± 13.3 to 94.8 ± 5.4 (P = 0.000), and the mean Karlsson score improved from 70.3 ± 12.2 to 93.8 ± 5.6 (P = 0.000). For the autograft group, the mean AOFAS score improved from 68.4 ± 10.0 to 94.7 ± 5.0 (P = 0.000), and the mean Karlsson score improved from 64.5 ± 14.4 to 95.0 ± 5.8 (P = 0.000). No significant differences were found between the allograft and autograft neither before (AOFAS P = 0.756, Karlsson P = 0.285) nor after (AOFAS P = 0.957, Karlsson P = 0.574) surgery. While the UTE T2* values in allograft were higher than those of autograft group both in anterior talofibular ligament (8.3 ± 1.0 vs 7.6 ± 1.1 P = 0.027) and intra-tunnel graft (7.8 ± 0.6 vs 7.2 ± 0.8 P = 0.045).

CONCLUSION

Both allograft and autograft reconstructions could get an ideal patient satisfaction and clinical functional outcomes at the follow-up. Higher T2* values were found in allograft group which indicated that autograft had some superiorities in respect of revascularization process, collagen structure, water content, and tendon properties.

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.

What Factors Influence the Biomechanical Properties of Allograft Tissue for ACL Reconstruction? A Systematic Review

BACKGROUND

Allograft tissue is used in 22% to 42% of anterior cruciate ligament (ACL) reconstructions. Clinical outcomes have been inconsistent with allograft tissue, with some series reporting no differences in outcomes and others reporting increased risk of failure. There are numerous variations in processing and preparation that may influence the eventual performance of allograft tissue in ACL reconstruction. We sought to perform a systematic review to summarize the factors that affect the biomechanical properties of allograft tissue for use in ACL reconstruction. Many factors might impact the biomechanical properties of allograft tissue, and these should be understood when considering using allograft tissue or when reporting outcomes from allograft reconstruction.

QUESTIONS/PURPOSES

What factors affect the biomechanical properties of allograft tissue used for ACL reconstruction?

METHODS

We performed a systematic review to identify studies on factors that influence the biomechanical properties of allograft tissue through PubMed and SCOPUS databases. We included cadaveric and animal studies that reported on results of biomechanical testing, whereas studies on fixation, histologic evaluation, and clinical outcomes were excluded. There were 319 unique publications identified through the search with 48 identified as relevant to answering the study question. For each study, we recorded the type of tissue tested, parameters investigated, and the effects on biomechanical behavior, including load to failure and stiffness. Primary factors identified to influence allograft tissue properties were graft tissue type, sterilization methods (irradiation and chemical processing), graft preparation, donor parameters, and biologic adjuncts.

RESULTS

Load to failure and graft stiffness varied across different tissue types, with nonlooped tibialis grafts exhibiting the lowest values. Studies on low-dose irradiation showed variable effects, whereas high-dose irradiation consistently produced decreased load to failure and stiffness values. Various chemical sterilization measures were also associated with negative effects on biomechanical properties. Prolonged freezing decreased load to failure, ultimate stress, and ultimate strain. Up to eight freeze-thaw cycles did not lead to differences in biomechanical properties of cadaveric grafts. Regional differences were noted in patellar tendon grafts, with the central third showing the highest load to failure and stiffness. Graft diameter strongly contributed to load-to-failure measurements. Age older than 40 years, and especially older than 65 years, negatively impacted biomechanical properties, whereas gender had minimal effect on the properties of allograft tissue. Biologic adjuncts show potential for improving in vivo properties of allograft tissue.

CONCLUSIONS

Future clinical studies on allograft ACL reconstruction should investigate in vivo graft performance with standardized allograft processing and preparation methods that limit the negative effects on the biomechanical properties of tissue. Additionally, biologic adjuncts may improve the biomechanical properties of allograft tissue, although future preclinical and clinical studies are necessary to clarify the role of these treatments.

CLINICAL RELEVANCE

Based on the findings of this systematic review that emphasize biomechanical properties of ACL allografts, surgeons should favor the use of central third patellar tendon or looped soft tissue grafts, maximize graft cross-sectional area, and favor grafts from donors younger than 40 years of age while avoiding grafts subjected to radiation doses > 20 kGy, chemical processing, or greater than eight freeze-thaw cycles.

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.

Use of three-dimensional finite element models of the lateral ankle ligaments to evaluate three surgical techniques

Objective To compare three surgical techniques for lateral ankle ligament reconstruction using finite element (FE) models. Methods A three-dimensional FE model of the left foot of a healthy volunteer and lateral collateral ligament injury models were developed. Three tendons [one-half of the autologous peroneus longus tendon (PLT), one-half of the peroneus brevis tendon (PBT), and an allogeneic tendon] were used for lateral collateral ligament reconstruction. The ankle varus stress and anterior drawer tests were performed to compare the three surgical techniques. Results The ankle varus stress test showed that the equivalent stresses of the anterior talofibular ligament (ATFL) (84.00 MPa) and calcaneofibular ligament (CFL) (27.01 MPa) were lower in allogeneic tendon reconstruction than in the other two techniques but similar to those of normal individuals (138.48 and 25.90 MPa, respectively). The anterior drawer test showed that the equivalent stresses of the ATFL and CFL in autologous PLT reconstruction (31.31 and 28.60 MPa, respectively) and PBT reconstruction (31.47 and 29.07 MPa, respectively) were lower than those in allogeneic tendon reconstruction (57.32 and 52.20 MPa, respectively). Conclusions The allogeneic tendon reconstruction outcome was similar to normal individuals. Allogeneic tendon reconstruction may be superior for lateral ankle ligament reconstruction without considering its complications.

Comparison of Knee Stability and Synovial Fluid Alterations in Anterior Cruciate Ligament Reconstruction With a Hamstring Autograft or an Allograft

This study compared knee stability and alterations in the composition of synovial fluid among patients who underwent arthroscopic anterior cruciate ligament (ACL) reconstruction with either a hamstring autograft or a hamstring allograft. This prospective cohort study enrolled 175 patients. Of these patients, 90 underwent hamstring tendon autograft ACL reconstruction. The remaining patients (n=85) underwent hamstring tendon allograft ACL reconstruction. All of the patients had a minimum of 1 year of follow-up (mean, 2.5 years). Side-to-side differences and the proportion of mononuclear cells in knee joint synovial fluid were measured at 5 time points (preoperatively and at postoperative weeks 1, 3, 6, and 12). During the early postoperative phase, side-to-side knee laxity was greater among the allograft group compared with the autograft group (P<.001). Additionally, among the allograft group, the proportion of mononuclear cells remained high at weeks 6 and 12 (mean, 90.0% and 88.9%, respectively) compared with a normal level in the autograft group (mean, 45.1% and 65.7%, separately). However, no significant difference was found between the 2 groups at final follow-up for range of motion, results of the Lachman test, results of the anterior drawer test, results of the pivot shift test, Lysholm score, bone tunnel enlargement, and graft failure rate (P>.05). These findings showed that, in the early postoperative phase, ACL reconstruction with a hamstring allograft resulted in greater knee laxity and immunologic response compared with the hamstring autograft group. However, at relatively long-term follow-up, both grafts achieved similar objective and subjective outcomes. [Orthopedics. 2017; 40(5):e892-e897.].

Comparison of artificial graft versus autograft in anterior cruciate ligament reconstruction: a meta-analysis

BACKGROUND

Critically evaluation and summarization for the outcomes between autografts and artificial grafts using in anterior cruciate ligament (ACL) reconstruction have not been performed currently. The purpose of this study is to compare the clinical outcomes between artificial ligaments and autografts at a short- to mid-term follow-up.

METHODS

A computerized search of the databases was conducted including Medline, Embase, and the Cochrane library. Only prospective or retrospective comparative studies with a minimum 2-year follow-up and a minimum sample size of 15 for each group were considered for inclusion. Two independent reviewers performed data extraction and methodological quality assessment. A Mantel-Haenszel analysis was used for pooling of results. Sensitivity analysis was performed in order to maintain the stability of results.

RESULTS

Seven studies were included in this study. The total sample size was 403 (autograft group: 206 patients; synthetic graft group: 197 patients). Four studies were randomized controlled trials. Two studies were retrospective comparative studies and one study was non-randomized prospective comparative study. In terms of instrumented laxity, patient-oriented outcomes and complications, no significant difference was occurred between new artificial ligaments and autografts. But the results of IKDC grades and instrumented laxity were worsen in early artificial ligaments compared to autografts.

CONCLUSIONS

The outcomes of new generation of artificial ligaments are similar to autografts at a short- to mid-term follow-up. However, the early artificial ligaments are not suggested for ACL reconstruction compared to autografts.

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

BACKGROUND

The optimal graft for anterior cruciate ligament reconstruction (ACLR) remains controversial.

PURPOSE

To compare the risk of aseptic revision between bone-patellar tendon-bone (BPTB) autografts, hamstring autografts, and soft tissue allografts.

STUDY DESIGN

Cohort study; Level of evidence, 2.

METHODS

Prospectively collected ACLR cases reconstructed with BPTB autografts, hamstring autografts, and soft tissue allografts were identified using the Kaiser Permanente ACLR Registry. Aseptic revision was the endpoint. The type of graft and allograft processing method (nonprocessed, <1.8-Mrad irradiation with and without chemical processing [Allowash or AlloTrue], ≥1.8-Mrad irradiation with and without chemical processing, and chemical processing alone [BioCleanse]) were the exposures evaluated. Analyses were adjusted for age, sex, and race. Kaplan-Meier curves and Cox proportional hazards models were employed.

RESULTS

The cohort included 14,015 cases: there were 8924 (63.7%) male patients, there were 6397 (45.6%) white patients, 4557 (32.5%) ACLRs used BPTB autografts, 3751 ACLRs (26.8%) used soft tissue allografts, and 5707 (40.7%) ACLRs used hamstring autografts. The median age was 34.6 years for soft tissue allografts, 24.3 years for hamstring autografts, and 22.0 years for BPTB autografts. The crude nonadjusted revision rates were 85 (1.9%) in BPTB autograft cases, 132 (2.3%) in hamstring autograft cases, and 83 (2.2%) in soft tissue allograft cases. After adjusting for age, sex, and race, compared with hamstring autografts, a higher risk of revision was found with allografts with ≥1.8 Mrad without chemical processing after 2.5 years (hazard ratio [HR], 3.88; 95% CI, 1.48-10.12) and ≥1.8 Mrad with chemical processing after 1 year (HR, 3.43; 95% CI, 1.58-7.47) and with BioCleanse processed grafts at any time point (HR, 3.02; 95% CI, 1.40-6.50). Nonprocessed allografts and those irradiated with <1.8 Mrad with or without chemical processing were not found to have a different risk of revision compared with hamstring autografts. Compared with BPTB autografts, a higher risk of revision was seen with hamstring autografts (HR, 1.51; 95% CI, 1.15-1.99) and BioCleanse processed allografts (HR, 4.67; 95% CI, 2.15-10.16). Allografts irradiated with <1.8 Mrad with chemical processing (Allowash or AlloTrue) (HR, 2.19; 95% CI, 1.42-3.38) and without chemical processing (HR, 2.31; 95% CI, 1.40-3.82) had a higher risk of revision, as did allografts with ≥1.8 Mrad without chemical processing after 2 years (HR, 6.30; 95% CI, 3.18-12.48) and ≥1.8 Mrad with chemical processing (Allowash or AlloTrue) after 1 year (HR, 5.03; 95% CI, 2.30-11.00) compared with BPTB autografts. Nonprocessed allografts did not have a higher risk of revision compared with autografts. With the numbers available, direct comparisons between the specific allograft processing methods were not possible.

CONCLUSION

When soft tissue allografts are used for ACLR, processing and time from surgery affect the risk of revision. Tissue processing has a significant effect on the risk of revision surgery, which is most profound with more highly processed grafts and increases with increasing follow-up time. Surgeons and patients need to be aware of the increased risks of revision with the various soft tissue allografts used for ACLR.

Increased Risk of Revision After Anterior Cruciate Ligament Reconstruction With Bone-Patellar Tendon-Bone Allografts Compared With Autografts

BACKGROUND

The use of allograft tissue for anterior cruciate ligament reconstruction (ACLR) remains controversial.

PURPOSE

To compare the risk of aseptic revision between bone-patellar tendon-bone (BPTB) autografts and BPTB allografts.

STUDY DESIGN

Cohort study; Level of evidence, 2.

METHODS

A retrospective cohort study of prospectively collected data was conducted using the Kaiser Permanente ACLR Registry. A cohort of patients who underwent primary unilateral ACLR with BPTB autografts and BPTB allografts was identified. Aseptic revision was the endpoint. The type of graft and allograft processing method (nonprocessed, <1.8-Mrad, and ≥1.8-Mrad irradiation) were the exposures of interest evaluated. Age (≤21 and ≥22 years) was evaluated as an effect modifier. Analyses were adjusted for age, sex, and race. Kaplan-Meier curves and Cox proportional hazards models were employed. Hazard ratios (HRs) and 95% CIs are provided.

RESULTS

The BPTB cohort consisted of 5586 patients: 3783 (67.7%) were male, 2359 (42.2%) were white, 1029 (18.4%) had allografts (nonprocessed: 155; <1.8 Mrad: 525; ≥1.8 Mrad: 288), and 4557 (81.6%) had autografts. The median age was 34.9 years (interquartile range [IQR], 25.4-44.0) for allograft cases and 22.0 years (IQR, 17.6-30.0) for autograft cases. The estimated cumulative revision rate at 2 years was 4.1% (95% CI, 2.9%-5.9%) for allografts and 1.7% (95% CI, 1.3%-2.2%) for autografts. BPTB allografts had a significantly higher adjusted risk of revision than BPTB autografts (HR, 4.54; 95% CI, 3.03-6.79; P < .001). This higher risk of revision was consistent with all allograft processing methods when compared with autografts and was also consistently higher in patients with allografts regardless of age.

CONCLUSION

When BPTB allograft tissue was used for ACLR, an overall 4.54 times adjusted higher risk of revision was observed compared with surgery performed with a BPTB autograft. Whether the tissue was irradiated with either high- or low-dose radiation, chemically processed, or not processed at all made little difference in the risk of revision. The differences in the revision risk were also consistent in younger and older patients. Surgeons and patients should be aware of the increased risk of revision when a BPTB allograft is used for ACLR.

Capacity of muscle derived stem cells and pericytes to promote tendon graft integration and ligamentization following anterior cruciate ligament reconstruction

PURPOSE

The aim of this study is to examine the capacity of muscle tissue preserved on hamstring tendons forming candy-stripe grafts in order to improve tendon to bone ingrowth and ligamentization. We hypothesized that muscle tissue does possess a stem cell population that could enhance the healing process of the ACL graft when preserved on the tendons.

METHODS

Human samples from gracilis and semitendinosus muscles were collected during ACL surgery from ten patients and from these tissue samples human muscle-derived stem cells and tendon-derived stem cells were isolated and propagated. Both stem cell populations were in-vitro differentiated into osteogenic lineage. Alkaline phosphatase activity was determined at days zero and 14 of the osteogenic induction and von Kossa staining to assess mineralization of the cultures. Total RNA was collected from osteoblast cultures and real time quantitative PCR was performed. Western-blot for osteocalcin and collagen type I followed protein isolation. Immunofluorescence double labeling of pericytes in muscle and tendon tissue was performed.

RESULTS

Mesenchymal stem cells from muscle and tendon tissue were isolated and expanded in cell culture. More time was needed to grow the tendon derived culture compared to muscle derived culture. Muscle derived stem cells exhibited more alkaline phosphatase actvity compared to tendon derived stem cells, whereas tendon derived stem cells formed more mineralized nodules after 14 days of osteoinduction. Muscle derived stem cells exhibited higher expression levels of bone sialoprotein, and tendon derived stem cells showed higher expression of dental-matrix-protein 1 and osteocalcin. Immunofluorescent staining against pericytes indicated that they are more abundant in muscle tissue.

CONCLUSIONS

These results indicate that muscle tissue is a better source of stem cells than tendon tissue. Achievement of this study is proof that there is vast innate capacity of muscle tissue for enhancement of bone-tendon integration and ligamentization of ACL hamstring grafts and consequently muscle tissue should not be treated as waste after harvesting.