Remodelling of human hamstring autografts after anterior cruciate ligament reconstruction

High-speed spinning of collagen microfibers comprising aligned fibrils for creating artificial tendons

Bundles of engineered collagen microfibers are promising synthetic tendons as substitutes for autogenous grafts. The purpose of this study was to develop high-speed and continuous spinning of collagen microfibers that involves stretching of collagen stream. Our study revealed the 'critical fibrillogenesis concentration (CFC)' of neutralized collagen solutions, which is defined as the upper limit of the collagen concentration at which neutralized collagen molecules remain stable as long as they are cooled (⩽10 °C). Neutralized collagen solutions at collagen concentrations slightly below the CFC formed cord-like collagen gels comprising longitudinally aligned fibrils when extruded from nozzles into an ethanol bath. Dry collagen microfibers with a controlled diameter ranging from 122 ± 2-31.2 ± 1.7 μm can be spun from the cord-like gels using nozzles of various sizes. The spinning process was improved by including stretching of collagen stream to further reduce diameter and increase linear velocity. We extruded a collagen solution through a 182 μm diameter nozzle while simultaneously stretching it in an ethanol bath during gelation and fiber formation. This process resembles the stretching of a melted thermoplastic resin because it solidifies during melt spinning. The mechanical properties of the stretched collagen microfibers were comparable to the highest literature values obtained using microfluidic wet spinning, as they exhibited longitudinally aligned fibrils both on their surface and in their core. Previous wet spinning methods were unable to generate collagen microfibers with a consistent tendon-like fibrillar arrangement throughout the samples. Although the tangent modulus (137 ± 7 MPa) and stress at break of the swollen bundles of stretched microfibers (13.8 ± 1.9 MPa) were lower than those of human anterior cruciate ligament, they were within the same order of magnitude. We developed a spinning technique that produces narrow collagen microfibers with a tendon-like arrangement that can serve as artificial fiber units for collagen-based synthetic tendons.

MRI Assessment of Tendon Graft After Lateral Ankle Ligament Reconstruction: Does Ligamentization Exist?

BACKGROUND

No description exists in the literature about the normal evolution of tendon graft after a lateral ankle ligament (LAL) reconstruction.

PURPOSE

To assess the magnetic resonance imaging (MRI) characteristics and the evolution of the tendon graft during different moments in the follow-up after an endoscopic reconstruction of the LAL.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

This prospective study included 37 consecutive patients who underwent an endoscopic reconstruction of the LAL with an autograft using the gracilis tendon to treat chronic ankle instability (CAI) resistant to nonoperative treatment (CAI group) and 16 patients without ankle instability (control group). All patients in the CAI group underwent a postoperative assessment at 6, 12, and 24 months using the Karlsson score and MRI examination. Only patients with good and excellent results were included in the study. Graft assessment consisted of qualitative measurements and quantitative evaluations of the reconstructed anterior talofibular ligament (RATFL) and reconstructed calcaneofibular ligament (RCFL), including signal-to-noise quotient (SNQ) and contrast-to-noise quotient (CNQ) measurements in proton density-fat suppressed (PD-FS) and T1-weighted sequences. The analysis of variance test was used to compare the SNQ and the CNQ at different time points for each sequence.

RESULTS

The MRI signal at 6 months was increased compared with that of the control group. Next, a significant signal decrease from 6 to 24 months was noted on PD-FS and T1-weighted images. SNQ measurements on PD-FS weighted images for both the RATFL and the RCFL demonstrated a significantly higher signal (P < .01 and P = .01, respectively) at 6 months compared with that of the control group. Subsequently, the signal decreased from 6 to 24 months. Similarly, CNQ measurements on PD-FS weighted images for both the RATFL and the RCFL demonstrated a significantly higher signal (P < .01 and P < .01, respectively) at 6 months compared with that of the control group. Subsequently, the signal decreased from 6 to 24 months.

CONCLUSION

The present study demonstrated an evolution of the MRI characteristics, suggesting a process of graft maturation toward ligamentization. This is important for clinical practice, as it suggests an evolution in graft properties and supports the possibility of creating a viable ligament.

Evaluation of Graft Maturation by MRI in Anterior Cruciate Ligament Reconstruction With and Without Concomitant Anterolateral Ligament Reconstruction

Background

Single-bundle anterior cruciate ligament reconstruction (SB-ACLR) with concomitant anterolateral ligament reconstruction (ALLR) has been associated with better clinical results when compared with isolated SB-ACLR. However, it is not known whether the improved outcomes are the result of the influence of concomitant ALLR on ACL graft healing.

Purpose/Hypothesis

The purpose of this study was to determine whether concomitant ALLR is associated with improved graft ligamentization after SB-ACLR. It was hypothesized that ALLR would not affect graft healing.

Study Design

Cohort study; Level of evidence, 3.

Methods

A 1 to 1 matching study was conducted on a consecutive series of 732 patients who underwent ACLR using a hamstring tendon autograft between 2007 and 2019. Patients were excluded if they had skeletal immaturity, inflammatory joint disease, multiple ligament reconstruction (other than ALLR), or a graft rupture. Patients with concomitant SB-ACLR and ALLR (SB-ACLR/ALLR) and isolated SB-ACLR were matched 1 to 1 based on age, sex, examination under anesthesia (EUA) grade 3 pivot shift, EUA grade 3 anterior drawer test, presence of graft impingement, sagittal graft angle, skeletal maturity, lack of generalized ligamentous laxity, and multiple ligamentous injury. A total of 40 matched pairs underwent postoperative magnetic resonance imaging (MRI) within the second year after surgery to assess graft ligamentization, which was measured by the signal-to-noise quotient (SNQ) of the ACL graft.

Results

The mean follow-up period was 41 months, with a 2-year follow-up rate of 80% in the SB-ACLR/ALLR group and 98% in the isolated SB-ACLR group. The mean duration between the index operation and MRI was 16.4 ± 3.4 months. No significant difference was observed in the SNQ of the ACL graft between the SB-ACLR/ALLR and SB-ACLR groups (6.9 ± 4.6 vs 5.2 ± 4.8, respectively; P = .066).

Conclusion

Study findings indicated that a concomitant ALLR at the time of hamstring tendon autograft ACLR did not affect graft healing as assessed by the SNQ of the ACL graft.

Growth progression of anterior cruciate ligament bone grafts in a pediatric population: magnetic resonance imaging analysis

BACKGROUND

In children, the incidence of anterior cruciate ligament (ACL) ruptures and reconstructions has significantly risen. Unfortunately, re-rupture rates following surgery are substantially higher in children than adults. Previous research suggests that smaller graft diameters are predictive of re-rupture.

OBJECTIVE

This study aimed to investigate the growth progression of the ACL bone graft, specifically in terms of width and length, within the intra-articular portion and tunnels, using successive magnetic resonance imaging (MRI) scans. The hypothesis was that the ACL grafts would undergo thinning during growth.

MATERIALS AND METHODS

The cohort comprised 100 patients who underwent ACL reconstruction. Among them, 37 patients with significant residual growth were selected for analysis. Of these, 4 patients experienced graft rupture, 5 had "over-the-top" techniques, 12 had missing MRI scans and 5 were lost to follow-up. Each included patient underwent two MRI scans; the analyses of which were conducted in a double-masked manner.

RESULTS

A total of 13 knees (and patients) were analyzed, with a mean ± SD (range) delay of residual growth between the two MRI scans of 3.3 + / - 1.4 (1.2-5.2) years. The graft exhibited elongation, thinning and eventual integration with the surrounding bone in the tunnels. Within the intra-articular portion, the mean [95% CI] increase in graft size between the two MRI scans was 30.8% in length and 14.8% in width. The width/length ratio in the intra-articular part was 20.4% on the first MRI and 20.8% on the second MRI. Since this difference in the ratio (+ 0.4%) was not statistically significant (P=0.425), our results indicate that the grafts remained stable in terms of proportions without thinning or thickening. Therefore, the initial hypothesis was validated for the tunnel portion but not the intra-articular portion of the grafts.

CONCLUSION

In children with open physes, ACL grafts demonstrate smooth growth progression in all dimensions. However, this finding does not fully explain the high rate of re-rupture observed in children. Further research is needed to elucidate the underlying factors contributing to re-rupture in this population.

Favorable Patient-Reported, Clinical, and Functional Outcomes 2 Years After ACL Repair and InternalBrace Augmentation Compared With ACL Reconstruction and Healthy Controls

BACKGROUND

Recently, interest in anterior cruciate ligament (ACL) preservation and repair after proximal ACL tears has been resurrected. Although good clinical outcomes have been reported in the literature with adequate patient selection, to date detailed scientific evidence for the functional benefit of primary ACL repair with ligament augmentation is scarce.

PURPOSE

To compare patient-reported, clinical, and functional outcomes in patients 2 years after ACL repair and InternalBrace augmentation (ACL-IB) with age- and sex-matched patients 2 years after ACL reconstruction (ACL-R) and with matched healthy controls.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

In total, 29 patients 2 years after ACL-IB, 27 sex- and age- matched patients 2 years after ACL-R (hamstring autografts), and 29 matched healthy controls were included. Patient-reported outcomes were assessed using the International Knee Documentation Committee score, Knee injury and Osteoarthritis Outcome Score, EQ-5D-5L, Tegner Activity Scale, and Anterior Cruciate Ligament Return to Sports after Injury scale. Surgery time was recorded. For clinical outcomes, range of motion and thigh and shank circumference were measured, and passive anterior translation was determined using the Rolimeter. Isokinetic muscle strength was measured using a Biodex dynamometer. The limb symmetry index (operated/contralateral or nondominant/dominant × 100), side-to-side differences (operated - contralateral, nondominant - dominant), and hamstring-quadriceps ratios were calculated for functional parameters. Failure and reoperation rates were not compared.

RESULTS

Two years after surgery, patients treated with ACL-IB showed good to excellent patient-reported outcomes comparable with those of patients after ACL-R. Surgery time, including concomitant surgeries, was significantly shorter in the ACL-IB group (mean, 81 minutes) compared with the ACL-R group (mean, 97 minutes) (P = .024). Isokinetic muscle strength was comparable between patient groups without significant differences in extensor and flexor strength or in hamstring-quadriceps ratios.

CONCLUSION

These results suggest that ACL-IB achieves comparable patient-reported, clinical, and functional outcomes with ACL-R at 2 years postoperatively and, after careful patient selection, should be considered as a valuable early treatment alternative for proximal ACL tears.

REGISTRATION

NCT04429165 (ClinicalTrials.gov identifier).

Effect of platelet-rich plasma on healing of autologous graft after anterior cruciate ligament reconstruction: a randomized control trial

Aim: This study aimed to assess the effect of platelet-rich plasma (PRP) on anterior cruciate ligament (ACL) graft healing at graft tunnel interface and ACL graft 6 months post-reconstruction. Material & methods: A randomized trial involving 87 patients was conducted, dividing them into PRP and non-PRP groups. Magnetic resonance imaging (MRI) and functional outcome measures were used to evaluate graft healing. Results: Out of the 87 patients, 80 were analyzed. The PRP group exhibited superior clinical and radiological outcomes compared with the non-PRP group, as indicated by Figueroas score, Lysholm score and knee range of motion. Conclusion: These findings demonstrate that PRP can be used as an adjunct therapy for ACL reconstruction, enhancing graft healing and improving patient outcomes. CTRI approval (Reg. No - CTRI/2018/11/016263).

Current trends in graft choice for anterior cruciate ligament reconstruction - part I: anatomy, biomechanics, graft incorporation and fixation

Graft selection in anterior cruciate ligament (ACL) reconstruction is critical, as it remains one of the most easily adjustable factors affecting graft rupture and reoperation rates. Commonly used autografts, including hamstring tendon, quadriceps tendon and bone-patellar-tendon-bone, are reported to be biomechanically equivalent or superior compared to the native ACL. Despite this, such grafts are unable to perfectly replicate the complex anatomical and histological characteristics of the native ACL. While there remains inconclusive evidence as to the superiority of one autograft in terms of graft incorporation and maturity, allografts appear to demonstrate slower incorporation and maturity compared to autografts. Graft fixation also affects graft properties and subsequent outcomes, with each technique having unique advantages and disadvantages that should be carefully considered during graft selection.

Comparison of ligamentization potential between anterior cruciate ligament-derived cells and adipose-derived mesenchymal stem cells reseeded to acellularized tendon allograft

Aims

To test the hypothesis that reseeded anterior cruciate ligament (ACL)-derived cells have a better ability to survive and integrate into tendon extracellular matrix (ECM) and accelerate the ligamentization process, compared to adipose-derived mesenchymal stem cells (ADMSCs).

Methods

Acellularized tibialis allograft tendons were used. Tendons were randomly reseeded with ACL-derived cells or ADMSCs. ACL-derived cells were harvested and isolated from remnants of ruptured ACLs during reconstruction surgery and cultured at passage three. Cell suspensions (200 µl) containing 2 × 106 ACL-derived cells or ADMSCs were prepared for the purpose of reseeding. At days 1, 3, and 7 post-reseeding, graft composites were assessed for repopulation with histological and immunohistochemical analysis. Matrix protein contents and gene expression levels were analyzed.

Results

In the graft reseeded with ACL-derived cells, a large number of elongated cells that integrated into the matrix were evident at day 3 and day 7. However, in the graft reseeded with ADMSCs, only a small number of elongated cells were found integrated into the matrix. Immunofluorescence for Ki-67 and type I collagen confirmed the pronounced production of type I collagen by Ki-67-positive ACL-derived cells integrated into the ECM. A messenger RNA (mRNA) expression assay demonstrated significantly higher gene expression levels of types I (p = 0.013) and III (p = 0.050) collagen in the composites reseeded with ACL-derived cells than ADMSCs.

Conclusion

ACL-derived cells, when reseeded to acellularized tendon graft, demonstrated earlier better survival and integration in the tendon ECM and resulted in higher gene expression levels of collagen, which may be essential to the normal ligamentization process compared to ADMSCs. Cite this article: Bone Joint Res 2022;11(11):777–786.

Additional tying on the adjustable-loop device improves the outcomes of anterior cruciate ligament reconstruction using hamstring autograft

PURPOSE

The purpose of this study was to verify the efficacy of a novel technique for additional tying on the adjustable-loop device to prevent stress concentration on the graft loop end and gradual loop lengthening.

METHODS

A total of 124 patients who underwent anterior cruciate ligament reconstruction using hamstring autografts from 2014 to 2017 were included in this retrospective study. After 1:1 propensity score matching, two groups were formed (group I: 50 patients without tying vs. group II: 50 patients with tying). Anterior laxity was evaluated using side-to-side differences. Tunnel length, loop length, and graft-tunnel gap were measured using follow-up magnetic resonance imaging. The signal-to-noise ratio was calculated at the loop end, loop inner side, tunnel entrance, and graft mid-substance. The clinical outcomes were assessed using the International Knee Documentation Committee score, Lysholm score, pivot shift test, and Lachman test.

RESULTS

The average follow-up period was 63.2 ± 4.8 and 53.8 ± 11.9 months in groups I and II, respectively. Anterior laxity showed that side-to-side differences improved significantly 6 months postoperatively in both the groups. Although the anterior laxity improved in group II (2.9 ± 1.0 to 1.6 ± 0.8, p < 0.001), it deteriorated in group I (2.5 ± 1.5 to 3.3 ± 1.3 mm, p < 0.001) at the final follow-up. The graft-tunnel gap was significantly larger in group I (p < 0.001). The signal-to-noise ratios of the loop end and loop inner side were significantly higher in group I (p < 0.001 and p = 0.020, respectively). The clinical outcomes at the final follow-up were not significantly different between the groups.

CONCLUSION

The additional tying on the adjustable-loop device was not superior to the control group in clinical stability examination or outcome. However, it was effective in anterior laxity measured by stress radiographs, preventing stress on the adjustable-loop device, and gradual graft loop lengthening.

LEVEL OF EVIDENCE

Level III.

Macroscopic and microscopic findings of multi-folded hamstring grafts of anatomical double-bundle ACL reconstruction 13 years after surgery

A 49-year-old woman underwent anatomic double-bundle anterior cruciate ligament reconstruction using a hamstring tendon. Due to knee osteoarthritis progression, total knee arthroplasty was performed 13 years after the surgery. The anteromedial (AM) bundle was composed partly of tendon-like tissue and partly of scar-like tissue. In the tendon-like part of the AM bundle, the collagen fibers were slightly loose and showed a low-frequency crimp structure with an ovoid cell shape. In contrast, the collagen arrangement in the scar-like part was irregular, edematous, and sparsely cell-dense, with an ovoid cell shape. The posterolateral bundles were generally composed of spindle-shaped cells, and the collagen was arranged in tight cohesion and had well-demarcated bundles with normal crimping. Within the tibial tunnel, the graft was mainly connected to the surrounding lamellar bone on the posterior sides, with sparser connections on the anterior and medial/lateral side. The findings of this long-term case provide valuable information to enable understanding of multiple-folded hamstring tendons.Level of evidence V.

An off-the-shelf decellularized and sterilized human bone-ACL-bone allograft for anterior cruciate ligament reconstruction

Approximately 1% of active individuals participating in sports rupture their anterior cruciate ligaments (ACL) every year, which is currently reconstructed using tendon autografts. Upon reconstruction, clinical issues of concern are ACL graft rupture, persistent knee instability, limited return to sports, and early onset of osteoarthritis (OA). This happens because tendon autografts do not have the same compositional, structural, and mechanical properties as a native ACL. To overcome these problems, we propose to use decellularized bone-ACL-bone allografts in ACL reconstruction (ACLR) as a mechanically robust, biocompatible, and immunologically safe alternative to autografts. Here, a decellularization protocol combined with sterilization using supercritical carbon dioxide (scCO₂) was used to thoroughly decellularize porcine and human ACLs attached to tibial and femoral bone blocks. The specimens were named ultrACLean and their compositional, structural, and mechanical properties were determined. Our results indicate that: 1) decellularization of ultrACLean allografts leads to the removal of nearly 97% of donor cells, 2) ultrACLean has mechanical properties which are not different to native ACL, 3) ultrACLean maintained similar collagen content and decreased GAG content compared to native ACL, and 4) ultrACLean is not cytotoxic to seeded tendon-derived cells in vitro. Results from an in vivo pilot experiment showed that ultrACLean is biocompatible and elicits a moderate immunological response. In summary, ultrACLean has proven to be a mechanically competent and biocompatible graft with the potential to be used in ACLR surgery.

Effect of Anterolateral Structure Augmentation on Graft Maturity After Anterior Cruciate Ligament Reconstruction: A Clinical and MRI Follow-up of 2 Years

BACKGROUND

Anterolateral structure augmentation (ALSA) has been applied to prevent residual rotatory instability and lower clinical failure rates after anterior cruciate ligament (ACL) reconstruction (ACLR); however, the effect of combined ALSA on the maturity of ACL grafts remains unknown.

PURPOSE

To evaluate the graft maturity and patient-reported outcomes in patients who underwent double-bundle ACLR with or without ALSA.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

A total of 92 patients who underwent double-bundle ACLR between January 2016 and July 2019 were included in the present study-44 patients with isolated ACLR (ACLR group) and 48 patients with combined ACLR and ALSA (ALSA group). Demographic characteristics, intraoperative findings, and patient-reported outcomes were prospectively collected. On postoperative magnetic resonance imaging at the 2-year follow-up, the signal-to-noise quotient (SNQ) values were separately calculated for 6 sections of the ACL graft, including the femoral intratunnel graft (FTG), intra-articular graft (IAG), and tibial intratunnel graft (TTG) of the anteromedial bundle (AMB) and the posterolateral bundle (PLB). Superior graft maturity was usually indicated by lower SNQ values.

RESULTS

The rates of return to preinjury sports were 47.9% and 27.3% in the ALSA and ACLR groups, respectively (difference, 20.6% [95% CI, 1.3%-40%]; P = .042). The AMB demonstrated significantly lower SNQ values in the ALSA group than in the ACLR group (FTG, 7.04 ± 3.65 vs 9.44 ± 4.51 [P = .006]; IAG, 6.62 ± 4.19 vs 8.77 ± 5.92 [P = .046]; TTG, 6.93 ± 3.82 vs 8.75 ± 4.55 [P = .040]). The SNQ values were significantly lower in the ALSA group for 2 of the 3 sections of the PLB (IAG, 7.73 ± 4.61 vs 9.88 ± 5.61 [P = .047]; TTG, 5.88 ± 3.10 vs 8.57 ± 4.32 [P = .001]). Partial lateral meniscectomy was correlated with higher SNQ values of the TTG in the AMB (β = 0.27; P = .009) and the PLB (β = 0.25; P = .008), with both groups pooled. Higher body mass index, smaller ACL graft-Blumensaat line angles, larger AMB graft diameters, and lower postoperative Tegner scores were also associated with inferior maturity in specific regions of the ACL graft.

CONCLUSION

A combination of ACLR and ALSA is a desirable option to improve the maturity of ACL grafts for patients who are young or expected to return to pivoting sports. Meanwhile, further investigations with higher levels of evidence and longer periods of follow-up are warranted.

Sufficient MRI graft structural integrity at 9 months after anterior cruciate ligament reconstruction with hamstring tendon autograft

PURPOSE

To assess the MRI-measured structural integrity of hamstring autograft at 9 months after anterior cruciate ligament reconstruction (ACLR) surgery.

METHODS

A prospective cohort study was conducted including 34 patients (mean age 36.8 ± 11.8 years; 73.5% males) who underwent ACLR with hamstring autograft. In addition, 36 patients (mean age 39.2 ± 10.5 years; 69.4% males) without any ACL injury were also reviewed and served as control group. The primary outcome used for examining graft maturity at 9 months after ACLR was the MRI-based signal-to-noise quotient (SNQ) of reconstructed ACL. SNQ values were stratified into 3 different categories: excellent: < 0.1; good: ≥ 0.1 and ≤ 0.19; fair: ≥ 0.2. The KT-1000 knee arthrometer was used to measure the side-to-side difference in the anterior tibial translation between the ACLR knee and the contralateral healthy knee in the ACLR group.

RESULTS

Reconstructed ACLs were found with a mean SNQ of 0.078 ± 0.061, while almost all ACL-reconstructed patients (97%; 33 out of 34) were found with excellent or good SNQ values (< 0.019). The mean KT-1000 in the ACLR group was 0.071 mm ± 0.926 mm, while there were no patients in the ACLR cohort with a KT-1000 value > 3 mm. The mean 9-months MRI-based SNQ of ACLR group was significantly higher compared to the mean MRI-based SNQ of the control group (p < 0.001). Multiple regression analysis showed no correlation between SNQ and age, gender, time from injury to ACLR, graft size, or simultaneous treatment of additional intra-articular knee lesions.

CONCLUSIONS

In this cohort of 34 ACL-reconstructed patients, 97% of hamstring tendon autografts demonstrated excellent/good MRI signal intensity and excellent functional results (KT-1000 < 3 mm) at 9 months after surgery. Based on this finding, it is suggested that return to sports after ACLR with hamstring autograft can be considered safe at 9 months post surgery. Furthermore, while structural integrity of the graft has been achieved at this time point, statistical differences found in SNQ values of ACL-reconstructed patients compared to ACLs of healthy individuals highlight the continuing process of graft maturation and remodelling.

LEVEL OF EVIDENCE

Level III.

Prospective Comparison of Functional and Radiological Outcomes of Arthroscopic Anterior Cruciate Ligament Reconstruction by Hamstring Graft Alone and Platelet-Rich Plasma Added to the Hamstring Graft

Aims and objectives: To measure the additional effect of platelet-rich plasma (PRP) on functional outcome of anterior cruciate ligament tear managed by augmenting anterior cruciate ligament (ACL) reconstruction with PRP.

Methods: The present study was conducted on patients with ACL tear admitted in the department of orthopaedics, King George’s Medical University, Lucknow wherein a total of 70 subjects were assigned into two groups of 35 patients each randomly, viz Group 1 in which the patients were treated by quadruple hamstring graft alone and Group 2 in which the patients were treated with augmented hamstring graft with PRP. The standardized anterior drawer test, Lachman’s test, Lysholm knee score were quantified both preoperatively and postoperatively at different follow-ups and also tibial tunnel widening was measured postoperatively at different follow-ups.

Result: The present study had 70 patients with ACL tears. The mean age of patients in non-PRP groups was 29.71 ±2.99 years while that in the PRP group was 28.34±4.32 years. On comparing the improvement in grades at pre-op, immediate postop, 6 weeks, and 3 months follow-ups, there was no statistically significant difference between the two groups. The tibial tunnel widening also showed no significant difference between the two groups.

Conclusion: In our study, it was found that both the groups showed improvements in grades of anterior drawer test and Lachman’s test postoperatively but the difference between both the groups was not significant. Similarly, while comparing the improvements in Lysholm knee score and tibial tunnel widening among both the groups, the difference was not significant. Follow up of 3 months was a limiting factor in our study. This technique needs further clinical evaluation to assess the long-term results.

RetroBRACE: clinical, socioeconomic and functional-biomechanical outcomes 2 years after ACL repair and InternalBrace augmentation in comparison to ACL reconstruction and healthy controls-experimental protocol of a non-randomised single-centre comparative study

INTRODUCTION

Despite good clinical outcomes reported in the literature, to date, scientific evidence for the functional and biomechanical benefit of primary anterior cruciate ligament (ACL) repair with augmentation is scarce. We present an experimental protocol for a detailed multimodal (clinical, socioeconomic, functional and biomechanical) comparative study in patients after primary ACL repair and InternalBrace augmentation, patients after ACL reconstruction and healthy controls.

METHODS AND ANALYSIS

In this non-randomised single-centre comparative study with prospective data collection with three arms (patients 2 years after ACL repair and InternalBrace augmentation; patients 2 years after ACL reconstruction using hamstring autografts; and healthy controls), 30 participants per study arm will be included. The study is designed as non-inferiority study with three arms. Required sample size was estimated based on data reported in the literature on muscle strength, proprioception and balance parameters, resulting in at least 28 participants per group. Outcome parameters include patient-reported outcome measures (EQ-5D-5L, Tegner Activity Scale, Knee Injury and Osteoarthritis Outcome Score (KOOS), International Knee Documentation Committee and ACL-Return to Sports Injury Scale), socio-economic parameters, anterior tibial translation, range of motion and functional-biomechanical data of the lower extremities. Functional-biomechanical parameters include proprioception, isokinetic muscle strength, single-leg balance, walking, running and single-leg hops with additional lower extremity 3D joint kinematics and kinetics and muscle activity. These parameters will be compared between limbs in patients, between groups and to the current literature.

ETHICS AND DISSEMINATION

The results of this study will be disseminated through peer-reviewed publications and presentations at national and international conferences. Ethical approval was obtained by the regional ethics board (Ethics Committee Northwest Switzerland EKNZ 2020-00551), and the study is registered at clinicaltrials.gov.Trial registration numberNCT04429165.

Influence of Age on Signal Intensity of Magnetic Resonance Imaging and Clinical Outcomes in Double-Bundle Anterior Cruciate Ligament Reconstruction: Comparisons Among Different Age Groups

BACKGROUND

Thus far, the clinical results of anterior cruciate ligament (ACL) reconstruction have been observed to be comparable between young and older patients. In contrast, age-related changes in the structural and mechanical properties of tendons used for autografts have been described. However, age-related changes associated with graft maturation remain poorly understood.

HYPOTHESES

The hypotheses of this study were that (1) clinical outcomes after ACL reconstruction would be comparable between younger and relatively older patients and (2) younger patients would show lower signal intensity changes on magnetic resonance imaging scans indicative of graft maturation that would be better than that in relatively older patients.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

We retrospectively evaluated 236 patients who underwent double-bundle ACL reconstruction via the outside-in technique using hamstring autograft between January 2012 and December 2015. The patients were categorized by age into 3 groups: <20 years old, 20 to 39 years old, and ≥40 years old. Clinical outcomes were evaluated using the subjective International Knee Documentation Committee (IKDC) score, Tegner activity scale, Lysholm score, and objective assessment of joint laxity 24 months after surgery. In addition, graft maturation was evaluated using magnetic resonance imaging-derived measures of the signal intensity ratio (SIR) at 3, 6, 12, and 24 months postoperatively. Clinical outcomes and graft maturation were compared among the 3 groups.

RESULTS

The SIR of both bundles increased from 3 months to 12 months and decreased by 24 months, showing the same tendency in all groups. No significant difference was found in the SIR among the 3 groups at any time point (P > .05). The IKDC score was significantly lower in the ≥40-year group than in the <20-year group (P < .01). In contrast, no significant differences were noted in other clinical outcomes.

CONCLUSION

Patients aged ≥40 years exhibited lower IKDC scores compared with younger patients, although the results of graft maturation were comparable.

Anterior cruciate ligament autograft maturation on sequential postoperative MRI is not correlated with clinical outcome and anterior knee stability

PURPOSE

Magnetic resonance imaging (MRI) signal intensity is correlated to structural postoperative changes of the anterior cruciate ligament (ACL) autograft. The purpose of this study was to investigate the ACL autograft maturation process via MRI over 2 years postoperatively, compare it to a native ACL signal and correlate the results with clinical outcome, return to preinjury sports levels, and knee laxity measurements.

METHODS

ACL autograft signal intensity was measured in 17 male patients (age, 28.3 ± 7.0 years) who underwent ACL reconstruction with hamstring autograft at 6 weeks, 3-, 6-, 12-, and 24 months postoperatively by 3 Tesla MRI. Controls with an intact ACL served as control group (22 males, 8 females; age, 26.7 ± 6.8 years). An ACL/PCL ratio (APR) and ACL/muscle ratio (AMR) was calculated to normalize signals to soft tissue signal. APR and AMR were compared across time and to native ACL signal. Clinical outcome scores (IKDC, Lysholm), return to preinjury sports levels (Tegner activity scale), and knee laxity measurement (KT-1000) were obtained and correlated to APR and AMR at the respective time points.

RESULTS

The APR and AMR of the ACL graft changed significantly from the lowest values at 6 weeks to reach the highest intensity after 6 months (p < 0.001). Then, the APR and AMR were significantly different from a native ACL 6 months after surgery (p < 0.01) but approached the APR and AMR of the native ACL at 1- and 2 years after surgery (p < 0.05). The APR changed significantly during the first 2 years postoperatively in the proximal (p < 0.001), mid-substance (p < 0.001), and distal (p < 0.01) intraarticular portion of the ACL autograft. A hypo-intense ACL MRI signal was associated with return to the preinjury sports level (p < 0.05). No correlation was found between ACL MRI graft signal and clinical outcome scores or KT-1000 measurements.

CONCLUSION

ACL grafts undergo a continuous maturation process in the first 2 years after surgery. The ACL graft signals became hyper-intense 6 months postoperatively and approximated the signal of a native intact ACL at 12- and 24 months. Patients with a hypo-intense ACL graft signal at 2 years follow-up were more likely to return to preinjury sports levels. The results of the present study provide a template for monitoring the normal ACL maturation process via MRI in case of prolonged clinical symptoms. However, subjective outcome and clinical examination of knee laxity remain important to assess the treatment success and to allow to return to sports.

LEVEL OF EVIDENCE

III.

Local variations in mechanical properties of human hamstring tendon autografts for anterior cruciate ligament reconstruction do not translate to a mechanically inferior strand

A ruptured anterior cruciate ligament (ACL) is often reconstructed with a multiple-strand autograft of a semitendinosus tendon alone or combined with a gracilis tendon. Up to 10% of patients experience graft rupture. This potentially results from excessive local tissue strains under physiological loading which could either result in direct mechanical failure of the graft or induce mechanobiological weakening. Since the original location in the hamstring tendon cannot be traced back from an autograft rupture site, this study explored whether clinical outcome could be further improved by avoiding specific locations or regions of human semitendinosus and/or gracilis tendons in ACL grafts due to potential mechanical or biochemical inferiority. Additionally, it examined numerically which clinically relevant graft configurations experience the lowest strains - and therefore the lowest rupture risk - when loaded with equal force. Remnant full-length gracilis tendons from human ACL reconstructions and full-length semitendinosus- and ipsilateral gracilis tendons of human cadaveric specimens were subjected to a stress-relaxation test. Locations at high risk of mechanical failure were identified using particle tracking to calculate local axial strains. As biochemical properties, the water-, collagen-, glycosaminoglycan- and DNA content per tissue region (representing graft strands) were determined. A viscoelastic lumped parameter model per tendon region was calculated. These models were applied in clinically relevant virtual graft configurations, which were exposed to physiological loading. Configurations that provided lower stiffness - i.e., experiencing higher strains under equal force - were assumed to be at higher risk of failure. Suitability of the gracilis tendon proper to replace semitendinosus muscle-tendon junction strands was examined. Deviations in local axial strains from the globally applied strain were of similar magnitude as the applied strain. Locations of maximum strains were uniformly distributed over tendon lengths. Biochemical compositions varied between tissue regions, but no trends were detected. Viscoelastic parameters were not significantly different between regions within a tendon, although semitendinosus tendons were stiffer than gracilis tendons. Virtual grafts with a full-length semitendinosus tendon alone or combined with a gracilis tendon displayed the lowest strains, whereas strains increased when gracilis tendon strands were tested for their suitability to replace semitendinosus muscle-tendon junction strands. Locations experiencing high local axial strains - which could increase risk of rupture - were present, but no specific region within any of the investigated graft configurations was found to be mechanically or biochemically deviant. Consequently, no specific tendon region could be indicated to provide a higher risk of rupture for mechanical or biochemical reasons. The semitendinosus tendon provided superior stiffness to a graft compared to the gracilis tendon. Therefore, based on our results it would be recommended to use the semitendinosus tendon, and use the gracilis tendon in cases where further reinforcement of the graft is needed to attain the desired length and cross-sectional area. All these data support current clinical standards.

ACL Study Group survey reveals the evolution of anterior cruciate ligament reconstruction graft choice over the past three decades

PURPOSE

Anterior cruciate ligament reconstruction (ACLR) aims to restore knee function and stability, allowing patients to return to the activities they enjoy and minimize further injury to the meniscus and cartilage and their ultimate progression to osteoarthritis. This study aims to present the evolution of graft choice over the last three decades according to members of the ACL Study Group (SG).

METHODS

Prior to the January 2020 ACL SG biannual meeting, a survey was administered consisting of 87 questions and 16 categories, including ACLR graft choice. A similar questionnaire has been administered prior to each meeting and survey results from the past 14 meetings (1992 through 2020, excluding 1994) are included in this work. Survey responses are reported as frequencies in percentages to quantify changes in practice over the surgery period.

RESULTS

In 1992, the most frequent graft choice for primary ACLR was bone-patellar tendon-bone (BTB) autograft, at nearly 90%. Hamstring tendon (HT) autografts have increased in popularity, currently over 50%, followed by just under 40% BTB autograft. Recently, quadriceps tendon (QT) autograft has increased in popularity since 2014.

CONCLUSION

Autograft (HT, BTB, QT) is an overwhelming favorite for primary ACLR over allograft. The preference for HT autograft increased over the study period relative to BTB autograft, with QT autograft gaining in popularity in recent years. Graft selection should be individualized for each patient and understanding the global trends in graft choice can help orthopaedic surgeons discuss graft options with their patients and determine the appropriate graft for each case.

LEVEL OF EVIDENCE

Level V, Expert Opinion.

Differential MMP 1 and MMP 13 expression in proliferation and ligamentization phases of graft remodeling in anterior cruciate ligament reconstruction

Purpose: Graft remodeling in anterior cruciate ligament reconstruction (ACLR) demonstrates three distinct phases: necrosis, proliferation and ligamentization. Biological enhancement involves modulating these processes, but the cellular activities related to extracellular matrix remodeling have not been investigated. We hypothesized that changes in matrix metalloproteinases (MMPs) 1 and 13 expression are involved in the transition of proliferation phase to ligamentization phase of graft remodeling.Materials and methods: Thirty-three rats underwent ACLR. Tendon grafts were harvested at week 1 (necrosis), 2 (proliferation), or 12 (ligamentization) post-operation for histological examination (n = 3), or for isolation of graft-derived cells (n = 8) for flow cytometry, proliferation assay, cell invasion assay, measurement of gene expression related to matrix remodeling (Col1A1, Col3A1, MMP1, tissue inhibitor of marix metalloproteinase 1 (TIMP1), and MMP13) and total MMP activities.Results: Increased cellularity in tendon graft was contributed by active cell proliferation and migration at week 2 post-operation, while decreased cellularity were paralleled by increased apoptosis at week 12. All genes measured (Col1A1, Col3A1, MMP1, TIMP1, and MMP13) increased significantly in week 2 cells compared to week 1 cells. MMP1 expression subsided at week 12, while MMP13 expression kept increasing till 12 weeks post-operation. Total MMP activities was 3-fold higher in cultured graft-derived cells from week 2 as compared to cells from week 12. Two distinct processes of graft remodeling were identified, characterized by increased MMP1 expression with cell proliferation and increased MMP13 expression with cell apoptosis.Conclusions: Unfavorable matrix remodeling during the proliferation phase is found with increased MMP1, while remodeling leading to ligamentization is associated with increased MMP13 expression.

Two-year postoperative MRI appearances of anterior cruciate ligament hamstrings autografts are not correlated with functional outcomes, anterior laxity, or patient age

Aims

MRI has been suggested as an objective method of assessing anterior crucate ligament (ACL) graft “ligamentization” after reconstruction. It has been proposed that the MRI appearances could be used as an indicator of graft maturity and used as part of a return-to-sport assessment. The aim of this study was to evaluate the correlation between MRI graft signal and postoperative functional scores, anterior knee laxity, and patient age at operation.

Methods

A consecutive cohort of 149 patients who had undergone semitendinosus autograft ACL reconstruction, using femoral and tibial adjustable loop fixations, were evaluated retrospectively postoperatively at two years. All underwent MRI analysis of the ACL graft, performed using signal-to-noise quotient (SNQ) and the Howell score. Functional outcome scores (Lysholm, Tegner, International Knee Documentation Committee (IKDC) subjective, and IKDC objective) were obtained and all patients underwent instrumented side-to-side anterior laxity differential laxity testing.

Results

Two-year postoperative mean outcome scores were: Tegner 6.5 (2 to 10); Lysholm 89.8 (SD 10.4; 52 to 100); and IKDC subjective 86.8 (SD 11.8; 51 to 100). The objective IKDC score was 86% A (128 patients), 13% B (19 patients), and 1% C (two patients). Mean side-to-side anterior laxity difference (134 N force) was 0.6 mm (SD 1.8; -4.1 to 5.6). Mean graft SNQ was 2.0 (SD 3.5; -14 to 17). Graft Howell scores were I (61%, 91 patients), II (25%, 37 patients), III (13%, 19 patients), and IV (1%, two patients). There was no correlation between either Howell score or SNQ with instrumented anterior or Lysholm, Tegner, and IKDC scores, nor was any correlation found between patient age and ACL graft SNQ or Howell score.

Conclusion

The two-year postoperative MRI appearances of four-strand, semitendinosus ACL autografts (as measured by SNQ and Howell score) do not appear to have a relationship with postoperative functional scores, instrumented anterior laxity, or patient age at surgery. Other tools for analysis of graft maturity should be developed.

Cite this article: Bone Jt Open 2021;2(8):569–575.

Chronological Changes in Anterior Knee Stability after Anatomical Anterior Cruciate Ligament Reconstruction Using Bone-Patellar Tendon-Bone and Hamstring Grafts

The clinical outcomes of anterior cruciate ligament (ACL) reconstruction are typically evaluated at specific time points only. This study aimed to characterize the chronological changes in anterior knee stability after anatomical ACL reconstruction and to compare the anterior knee stability achieved with bone-patellar tendon-bone (BPTB) and hamstring tendon (HT) grafts. A total of 59 patients underwent anatomical rectangular tunnel ACL reconstruction using the BPTB graft and 23 patients underwent anatomical double-bundle ACL reconstruction using the HT graft. Anterior knee stability was quantitatively assessed using the KneeLax 3 arthrometer at 6 months, 1 year, and 2 years after surgery using side-to-side differences. The values for anterior knee stability using the BPTB graft were 0.3 mm after 6 months, 0.2 mm after 1 year, and 0.2 mm after 2 years, and no significant differences were observed during the postoperative study period. Meanwhile, the values for anterior knee stability using the HT graft were -0.3 mm after 6 months, 0.5 mm after 1 year, and 1.2 mm after 2 years, and anterior knee stability decreased chronologically from 6 months up to 2 years. Regarding anterior stability, the HT graft showed significant laxity compared with the BPTB graft only after 2 years. No chronological changes in anterior stability were observed from 6 months up to 2 years after ACL reconstruction using the BPTB graft, whereas anterior laxity developed during the same period after ACL reconstruction using the HT graft. This is a Level IV, therapeutic case series study.

Remnant preservation does not affect accuracy of tibial tunnel positioning in single-bundle ACL reconstruction

PURPOSE

Remnant preservation, in anterior cruciate ligament (ACL) reconstruction, has potential biological advantages. However, graft positioning remains vital to functional outcome and the prevention of failure. The aim of this study was to investigate the accuracy and precision of tibial tunnel positioning in remnant preservation single-bundle hamstring reconstruction.

METHODS

Fifty consecutive adult patients, with isolated ACL rupture, were recruited to a prospective study. Remnant preservation was performed in all cases where > 25% of the native ACL was present. Three-dimensional computer tomography was preformed 3-6 months post-operatively to assess tibial tunnel position (using a grid-based measurement). Accuracy and precision of this technique were assessed against published anatomical data in direct comparison with the group where remnant preservation could not be performed.

RESULTS

Two patients withdrew following surgery. In the remaining groups (31 remnant preservation; 17 non-remnant preservation), no difference was demonstrated in tunnel position (40.4 ± 6.7% (anterior-to-posterior) and 47.4 ± 1.5% (medial-to-lateral) vs. 38.8 ± 4.9% and 46.7 ± 1.5%, respectively; n.s.), accuracy (6.1% vs. 4.8%; n.s.) or precision (3.9% vs. 2.8%; n.s.).

CONCLUSIONS

Remnant preservation can be safely performed without compromising tunnel position. Therefore, the potential benefits of this technique can be utilised, in clinical practice, without sacrificing the ability to optimize tibial tunnel positioning.

LEVEL OF EVIDENCE

III.

All-Inside Anterior Cruciate Ligament Reconstruction With Augmentation Using the Native Anterior Cruciate Ligament Remnant by Suture Approximation

Anterior cruciate ligament (ACL) rupture remains a debilitating orthopaedic pathology with a substantial economic and psychological burden on patients, especially athletes. The purpose of ACL reconstruction is to attain maximum joint stability and functionality, allowing patients to resume their previous level of activity. Several graft options and techniques are available for ACL reconstruction. The all-inside remnant-preservation technique is a minimally invasive approach aiming for improved proprioception, better graft integration, and increased graft strength via ACL augmentation by suture approximation with an optimal anatomic reconstruction. ACL augmentation is associated with a decreased risk of rerupture. Moreover, enhancement of knee proprioception via the presented technique allows an early return to activity by patients because weight bearing (with a brace) can be initiated as early as day 1 postoperatively. Patients can resume running activities by 2 months postoperatively and return to pivot sports by 3 months postoperatively. Despite this surgical procedure being technically demanding, it is associated with improved clinical outcomes and functional capacities. Patients are also found to better tolerate the postoperative rehabilitation protocol.

Fibroblasts From Common Anterior Cruciate Ligament Tendon Grafts Exhibit Different Biologic Responses to Mechanical Strain

BACKGROUND

Different tendons are chosen for anterior cruciate ligament (ACL) reconstruction based on perceived advantages and disadvantages, yet there is a relative paucity of information regarding biologic responsiveness of commonly used tendon grafts to mechanical strain.

PURPOSE

To evaluate the in vitro responses of graft fibroblasts derived from tendons used for ACL reconstruction to clinically relevant strain levels.

STUDY DESIGN

Controlled laboratory study.

METHODS

Twelve quadriceps tendons (QTs), 12 patellar tendons (PTs), and 9 hamstring tendons (HTs) were harvested from skeletally mature dogs (n = 16). Tendon fibroblasts were isolated and seeded onto BioFlex plates (1 × 10⁵ cells/well). Cells were subjected to 3 strain conditions (stress deprivation, 0%; physiologic, 4%; high, 10%) for 5 days. Media were collected for proinflammatory and metabolic assays. RNA was extracted for gene expression analysis using real-time reverse transcription polymerase chain reaction.

RESULTS

Stress deprivation elicited significantly higher metabolic activity from HT and PT cells than from QT cells (P < .001 and P = .001, respectively). There were no differences in metabolic activity among all 3 graft fibroblasts at physiologic and high strain. COL-1 expression was significantly higher in PT versus HT during physiologic strain (P = .007). No significant differences with COL-3 expression were seen. TIMP-1 (P = .01) expression was higher in PT versus HT under physiologic strain. Scleraxis expression was higher in PT versus HT (P = .007) under physiologic strain. A strain-dependent increase in PGE2 levels occurred for all grafts. At physiologic strain conditions, HT produced significantly higher levels of PGE2 versus QT (P < .001) and PT (P = .005).

CONCLUSION

Fibroblasts from common ACL graft tissues exhibited different metabolic responses to mechanical strain. On the basis of these data, we conclude that early production of extracellular matrix and proinflammatory responses from ACL grafts are dependent on mechanical loading and graft source.

CLINICAL RELEVANCE

Graft-specific differences in ACL reconstruction outcomes are known to exist. Our results suggest that there are differences in the biologic responsiveness of cells from the tendon grafts used in ACL reconstruction, which are dependent on strain levels and graft source. The biologic properties of the tissue used for ACL reconstruction should be considered when selecting graft source.

Histomorphological Alterations of Human Anterior Cruciate Ligament Grafts During Mid-Term and Long-Term Remodeling

Objective

The aim of the present paper is to analyze mid‐term and long‐term alterations of human anterior cruciate ligament (ACL) grafts during the remodeling process with special regards to cellularity, α‐smooth muscle protein (αSMP) expression, and crimp length in comparison to the native ACL.

Methods

A total of 34 patients were included (23 male and 11 female). Biopsies of 13 semitendinosus tendon and 14 patellar tendon autografts were obtained during surgical revision secondary to an ACL reconstruction. According to the interval between the index procedure and sample collection, the patients were divided into four groups: 4–12 months, 13–60 months, 61–108 months, and >108 months. Seven samples of native ruptured ACL tissue obtained during surgical intervention served as control. All biopsies were taken from the intraligamentous part of the ACL or the graft. Histomorphological and immunohistochemical analyses were conducted after samples were stained using hematoxylin–eosin, Giemsa, and αSMP enzyme‐labeled antibodies. The total cell density, the numbers of fibroblasts and fibrocytes, the fibroblast/fibrocyte ratio, the number of αSMP+ cell nuclei, and the percentage of αSMP+ cells per fibroblast as well as the crimp lengths were determined using light microscopy.

Results

In the early phase of remodeling, the grafts featured extensively high total cell counts (1021.2 ± 327.8, P = 0.001), with high numbers of fibroblasts (841.4 ± 245.2, P = 0.002), fibrocytes (174.5 ± 113.0, P = 0.04), and αSMP+ cells (78.3 ± 95.0, P = 0.02) compared to controls (390.1 ± 141.7, 304.5 ± 160.8, 65.6 ± 31.4 and 2.3 ± 2.6, respectively). Thereafter, the numbers of all cell entities decreased. After more than 108 months, the percentage of αSMP+ cells per fibroblast reached physiological values (ratio 1.3 ± 1.0, P = 0.41; control 0.8 ± 0.8), while the total cell count (834.3 ± 183.7, P = 0.001) as well as the numbers of fibroblasts (663.5 ± 192.6, P = 0.006) and fibrocytes (134.1 ± 73.0, P = 0.049) remained significantly high. The fibroblast/fibrocyte ratio showed no significant alterations over the course of time compared to the controls. The collagen crimp lengths were elongated by tendency in the early phase (28.8 ± 12.9 mm, P = 0.15; control 20.7 ± 2.2 mm) and significantly shortened over time, with the lowest values in the long term (14.8 ± 2.0 mm, P = 0.001). The comparison of biopsies from semitendinosus tendon and patellar tendon autografts revealed no significant differences for any of the histomorphological parameters investigated.

Conclusion

This study reveals distinctive mid‐term and long‐term immunomorphological alterations during human ACL graft remodeling. These data clearly indicate that the remodeling is a process that continues for 9 years or more. Furthermore, it seems to be a process of adaptation rather than full restoration. Even in the long run, several biological properties of the native ACL are not completely reestablished.

ACL Growth With Age in Pediatric Patients: An MRI Study

BACKGROUND

There is limited knowledge of morphologic changes of the anterior cruciate ligament (ACL) during childhood. The purpose of the study is to describe normal ACL growth in pediatric patients.

METHODS

We performed retrospective review of patients under 19 years of age with at least 2 serial magnetic resonance imaging (MRI) examinations of the same knee without ACL tear. The parameters measured included length of the ACL, width of the ACL in sagittal and coronal planes, physeal status, ACL-tibial inclination angle, Notch Width Index, ACL tibial attachment width and midpoint, and anterior to posterior length and height of the tibial epiphysis. Pearson correlation coefficients were calculated to determine the strength of correlation of each parameter relative to age. Growth curves were calculated for individual parameters, producing a predictive model for growth of the ACL over time.

RESULTS

One hundred forty-seven patients (365 MRIs) were included. The average age at initial MRI was 12.2 years (range: 1.2 to 18.4 y). The Pearson correlation coefficient for each parameter was statistically significant relative to age. Younger patients had more oblique, anteriorly attached ACLs. Three distinct phases of growth were observed: patients age 1.5 to 5.75 years average 2.25 mm of growth per year; patients aged 6 to 11.5 average 1.46 mm of growth per year; growth slows at age 11.75, stopping by 18.5 years. The growth model for ACL sagittal width increased 0.45 mm/y from age 1.5 to 14.5 after which it plateaus, whereas coronal width increased 0.22 mm/y from age 1.5 to 18.75.

CONCLUSIONS

In the pediatric patient, the ACL grows in length and width in a predictable manner until age 18. This model aids clinicians in predicting normal ACL parameters for anatomic reconstruction procedures in the skeletally immature patient.

LEVEL OF EVIDENCE

Level IV.

Diffusion Tensor Imaging for Quantitative Assessment of Anterior Cruciate Ligament Injury Grades and Graft

BACKGROUND

As the need for quantitative assessment of anterior cruciate ligament (ACL) injuries and ACL graft increases, diffusion tensor imaging (DTI) becomes a more valuable measuring tool. However, DTI changes in differing injury grades of ACL and longitudinal graft remain unclear.

PURPOSE

To investigate the diagnostic performance of DTI in quantitatively assessing ACL injury severity and the development of ACL grafts within 6 months of surgery.

STUDY TYPE

A cohort study.

SUBJECTS

Thirty-five patients diagnosed with grades I-IV ACL injuries and 20 volunteers as controls were recruited.

FIELD STRENGTH/SEQUENCE

T₁ -weighted, T₂ -weighted, proton density (PD)-weighted, and DTI at 3.0T MRI.

ASSESSMENT

ACL injury grades in arthroscopic images and DTI quantitative data were evaluated from July 2016 to July 2018.

STATISTICAL TESTS

Chi-square test, analysis of variance, Spearman correlation analysis, and receiver operator characteristic (ROC) curves.

RESULTS

Both fractional anisotropy (FA) (r = -0.898, P < 0.05) and apparent diffusion coefficient (ADC) (r = 0.851, P < 0.05) were significantly correlated with the severity of ACL injuries. The area under the curve (AUC) values for differentiation between low- and high-grade ACL injuries with FA and ADC were 0.973 and 0.963, respectively. Although there were no significant differences in FA (P > 0.05) and ADC (P > 0.05) between grades I and II ACL injuries or in ADC (P > 0.05) between grades III and IV, there were significant differences in FA and ADC between two grades (P < 0.05). There were significant differences in FA (P < 0.05) and ADC (P < 0.05) between normal ACL and 3-month graft postoperation, as well as in ADC values between 3-month and 6-month graft postoperation (P < 0.05).

DATA CONCLUSION

DTI could be used to quantitatively evaluate the ACL injury grades and the development of ACL grafts. The diagnostic efficiency of FA values was higher than that of ADC values.

LEVEL OF EVIDENCE

1 TECHNICAL EFFICACY: Stage 3.

Immunohistochemical analysis of sensory corpuscles in human transplants of the anterior cruciate ligament

Background

Sensory nerve endings in ligaments play an important role for the proprioceptive function. Clinical trials show that the sense of body position does not fully recover in the knee joint after reconstructive surgery of the ruptured anterior cruciate ligament. The aim of this study is to identify sensory corpuscles in autogenous and allogenous transplants of the ligament and to compare their quantity between the used allografts and autografts.

Methods

Thirty-three patients were included in this study. Three patellar tendon allografts, 14 patellar tendon autografts and 12 semitendinosus autografts were harvested during revision surgery after traumatic rerupture of the graft. The control consisted of 4 healthy anterior cruciate ligaments after fresh rupture. After haematoxylin staining, immunohistochemical analysis was performed using antibodies against S100, p75 and PGP9.5. Microscopical examination was carried out, and the number of mechanoreceptors was counted. Statistical analysis was performed using the Mann-Whitney U test.

Results

Two types of mechanoreceptors were identified in each graft: Ruffini corpuscles and free nerve endings. The number of Ruffini corpuscles per square centimeter was the highest in the control. Comparing the grafts, the highest number of receptors could be detected in the semitendinosus autograft. The amount of free nerve endings was higher in the semitendinosus and patellar tendon autografts than in the control; the allografts showed the lowest number of receptors. With increasing time after reconstruction, the number of both types of receptors showed a decrease in the semitendinosus graft, whereas it increased in the patellar tendon graft and allograft. The number of mechanoreceptors in the semitendinosus and patellar tendon graft decreased over time after graft-failure, whereas it increased slightly in the allograft.

Conclusion

This study was the first to identify mechanoreceptors in human transplants of the anterior cruciate ligament. The partial increase in the number of receptors over time after reconstruction could indicate a reinnervation of the grafts.

Diffusion tensor imaging of the anterior cruciate ligament graft following reconstruction: a longitudinal study

OBJECTIVE

To longitudinally monitor remodeling of human autograft following anterior cruciate ligament (ACL) reconstruction with DTI.

METHODS

Twenty-eight patients underwent DTI follow-up at 3, 8, and 14 months after clinically successful ACL reconstruction with tendon autograft. Among these, 18 patients had a concomitant lateral extra-articular procedure (LET). DTI data from 7 healthy volunteers was also obtained. Diffusion parameters (fractional anisotropy, FA; mean diffusivity, MD; axial diffusivity, AD; and radial diffusivity, RD) were evaluated within the fiber tractography volumes of the ACL graft and posterior cruciate ligament (PCL) in all patients. Data were analyzed using a linear mixed-effects model with post hoc testing using Bonferroni-Holm correction for multiple testing. The effect of additional LET was studied.

RESULTS

The ACL graft showed a significant decrease of FA over time (F = 4.00, p = 0.025), while the diffusivities did not significantly change over time. For PCL there were no significant DTI changes over time. A different evolution over time between patients with and without LET was noted for all diffusivity values of the ACL graft with reduced AD values in patients with LET at 8 months postoperatively (p = 0.048; adjusted p = 0.387). DTI metrics of the ACL graft differed largely from both native ACL and tendon at 14 months postoperatively.

CONCLUSION

Our study has shown the potential of DTI to longitudinally monitor the remodeling process in human ACL reconstruction. DTI analysis indicates that graft remodeling is incomplete at 14 months postoperatively.

KEY POINTS

• DTI can be used to longitudinally monitor the remodeling process in human ACL reconstruction. • DTI analysis indicates that autograft remodeling is incomplete at 14 months postoperatively. • DTI may be helpful for evaluating new ACL treatments.

Assessment of Graft Maturity After Anterior Cruciate Ligament Reconstruction Using Autografts: A Systematic Review of Biopsy and Magnetic Resonance Imaging studies

Purpose

The purpose of this investigation was to evaluate systematically the literature concerning biopsy, MRI signal to noise quotient (SNQ) and clinical outcomes in graft-maturity assessment after autograft anterior cruciate ligament reconstruction (ACLR) and their possible relationships.

Methods

The systematic review was reported and conducted according to the PRISMA (Preferred Reporting Items for Systematic reviews and Meta-Analyses) guidelines. Studies through May 2019 evaluating methods of intra-articular ACL autograft maturity assessment were considered for inclusion. Eligible methods were histologic studies of biopsy specimens and conventional MRI studies reporting serial SNQ and/or correlation with clinical parameters.

Results

Ten biopsy studies and 13 imaging studies, with a total of 706 patients, met the inclusion criteria. Biopsy studies show that graft remodeling undergoes an early healing phase, a phase of remodeling or proliferation and a ligamentization phase as an ongoing process even 1 year after surgery. Imaging studies showed an initial increase in SNQ, peaking at approximately 6 months, followed by a gradual decrease over time. There is no evident correlation between graft SNQ and knee stability outcome scores at the short- and long-term follow-up after ACLR.

Conclusions

The remodeling of the graft is an ongoing process even 1 year after ACLR, based on human biopsy studies. MRI SNQ peaked at approximately 6 months, followed by a gradual decrease over time. Heterogeneity of the MRI methods and technical restrictions used in the current literature limit prediction of graft maturity and clinical and functional outcome measures by means of MRI graft SNQ after ACLR.

Level of evidence

Level IV, systematic review, including level III and IV studies.

Identifying potential patient-specific predictors for anterior cruciate ligament reconstruction outcome - a diagnostic in vitro tissue remodeling platform

Purpose

Upon anterior cruciate ligament (ACL) rupture, reconstruction is often required, with the hamstring tendon autograft as most widely used treatment. Post-operative autograft remodeling enhances graft rupture risk, which occurs in up to 10% of the patient population, increasing up to 30% of patients aged under 20 years. Therefore, this research aimed to identify potential biological predictors for graft rupture, derived from patient-specific tissue remodeling-related cell properties in an in vitro micro-tissue platform.

Methods

Hamstring tendon-derived cells were obtained from remnant autograft tissue after ACL reconstructions (36 patients, aged 12–55 years), and seeded in collagen I gels on a micro-tissue platform. Micro-tissue compaction over time – induced by altering the boundary constraints – was monitored. Pro-collagen I expression was assessed using ELISA, and protein expression of tenomodulin and α-smooth muscle actin were measured using Western blot. Expression and activity of matrix metalloproteinase 2 were determined using gelatin zymography.

Results

Only micro-tissues corresponding to younger patients occasionally released themselves from the constraining posts. Pro-collagen I expression was significantly higher in younger patients. Differences in α-smooth muscle actin and tenomodulin expression between patients were found, but these were age-independent. Active matrix metalloproteinase 2 expression was slightly more abundant in younger patients.

Conclusions

The presented micro-tissue platform exposed patient-specific remodeling-related differences between tendon-derived cells, with the micro-tissues that released from constraining posts and pro-collagen I expression best reflecting the clinical age-dependency of graft rupture. These properties can be the starting point in the quest for potential predictors for identifying individual patients at risk for graft rupture.

Anterior cruciate ligament grafts display differential maturation patterns on magnetic resonance imaging following reconstruction: a systematic review

PURPOSE

The appearance of anterior cruciate ligament (ACL) grafts on magnetic resonance imaging (MRI) is related to graft maturity and mechanical strength after ACL reconstruction (ACLR). Accordingly, the purpose of this review was to quantitatively analyze reports of serial MRI of the ACL graft during the first year following ACLR; the hypothesis tested was that normalized MRI signal intensity would differ significantly by ACL graft type, graft source, and postoperative time.

METHODS

PubMed, Scopus, and CINAHL were searched for all studies published prior to June 2018 reporting MRI signal intensity of the ACL graft at multiple time points during the first postoperative year after ACLR. Signal intensity values at 6 and 12 months post-ACLR were normalized to initial measurements and analyzed using a least-squares regression model to study the independent variables of postoperative time, graft type, and graft source on the normalized MRI signal intensity.

RESULTS

An effect of graft type (P = 0.001) with interactions of graft type * time (P = 0.012) and graft source * time (P = 0.001) were observed. Post hoc analyses revealed greater predicted normalized MRI signal intensity of patellar tendon autografts than both hamstring (P = 0.008) and hamstring with remnant preservation (P = 0.001) autografts at postoperative month 12.

CONCLUSION

MRI signal varies with graft type, graft source, and time after ACLR. Enhanced graft maturity during the first postoperative year was associated with hamstring autografts, with and without remnant preservation. Serial MRI imaging during the first postoperative year may be clinically useful to identify biologically or mechanically deficient ACL grafts at risk for failure.

LEVEL OF EVIDENCE

IV.

Japanese Orthopaedic Association (JOA) clinical practice guidelines on the management of anterior cruciate ligament injury - Secondary publication

BACKGROUND

This clinical guideline presents recommendations for the management of patients with anterior cruciate ligament (ACL) injury, endorsed by the Japanese Orthopaedic Association (JOA) and Japanese Orthopaedic Society of Knee, Arthroscopy and Sports Medicine (JOSKAS).

METHODS

The JOA ACL guideline committee revised the previous guideline based on "Medical Information Network Distribution Service Handbook for Clinical Practice Guideline Development 2014", which proposed a desirable method for preparing clinical guidelines in Japan. Furthermore, the importance of "the balance of benefit and harm" was also emphasized. This guideline consists of 21 clinical questions (CQ) and 23 background questions (BQ). For each CQ, outcomes from the literature were collected and evaluated systematically according to the adopted study design.

RESULTS

We evaluated the objectives and results of each study in order to make a decision on the level of evidence so as to integrate the results with our recommendations for each CQ. For BQ, the guideline committee proposed recommendations based on the literature.

CONCLUSIONS

This guideline is intended to be used by physicians, orthopedic surgeons, physical therapists, and athletic trainers managing ACL injuries. We hope that this guideline is useful for appropriate decision-making and improved management of ACL injuries.

Clinical experience with woven and parallel hamstring-tendon anterior cruciate ligament reconstruction

PURPOSE

The purpose of this study was to determine the effect of the weave technique for hamstring graft preparation on the diameter of the prepared graft, functional outcome, and need for harvesting of semitendinosus and gracilis (ST + G) or semitendinosus alone (ST).

MATERIALS AND METHODS

This retrospective study evaluated 340 patients who underwent arthroscopic anterior cruciate ligament (ACL) reconstruction from January 2013 to December 2015. Our protocol for graft preparation is that the graft length must be a minimum of 8 cm and the diameter must be between 7 and 10 mm. The parallel-graft preparation technique was used in 189 patient and the weave technique was used in 151 patients. Outcome was measured by using stress radiographs and International Knee Documentation Committee (IKDC) 2000 score.

RESULTS

In the parallel-graft preparation group, ST + G was used in 99 patients and ST was used in 90 patients. In the weave-graft preparation group, ST + G was used in 38 patients and ST alone was sufficient in 113 patients. The need for G harvest was less in the weave-technique group (p < 0.0001). There was no statistically significant difference at 2 years of follow-up in stress laxiometry, IKDC 2000 scores and rerupture rates between the two groups.

CONCLUSION

The weave technique helps to reduce the need for G harvest without compromising functional outcome. Level of evidence IV.

Inferior graft maturity in the PL bundle after autograft hamstring double-bundle ACL reconstruction

PURPOSE

The purpose of this study was to evaluate the signal/noise quotient (SNQ) for graft maturation and the serial changes observed in the magnetic resonance imaging (MRI) findings after double-bundle (DB) anterior cruciate ligament (ACL) reconstruction using a hamstring tendon autograft at a minimum of 5 years after surgery.

METHODS

Forty-five patients who underwent DB ACL reconstruction between 2007 and 2010 were included in this prospective study. All participants underwent postoperative MRI at 3 weeks and 3, 6, 9 and 12, 18, 24, 36, 48 and 50 months. The signal intensity (SI) characteristics of the reconstructed graft were evaluated on oblique axial proton density-weighted MR imaging (PDWI) perpendicular to the grafts. The signal/noise quotient (SNQ) was calculated to quantitatively determine the normalized SI. The SNQ of the AMB and PLB was evaluated separately.

RESULTS

The mean SNQ of the AM bundle (AMB) continued to increase until 6 months after surgery (5.2 ± 1.2), and then gradually decreased and became well stabilized by 18 months (3.3 ± 0.5), after which it remained unchanged. On the other hand, the mean SNQ of the PL bundle (PLB) continued to increase until 9 months after surgery (6.2 ± 1.1), and then decreased incrementally and became well stabilized by 24 months (4.1 ± 0.5). The SI of PLB was significantly higher than that of AMB between 3 and 24 months (p = 0.04, 0.03, 0.01, 0.04, 0.02 and 0.03, respectively).

CONCLUSIONS

These results indicate that at least 18 months is needed after ACL reconstruction to sufficiently restore the SI of the AMB, while at least 24 months are needed to for the PLB. The SI of the PLB was significantly higher than that of the AMB at 3-24 months after surgery, indicating that the PLB showed inferior graft maturity to the AMB until 24 months after surgery. For clinical relevance, the correct understanding of serial changes in graft maturation may potentially be used in decision-making regarding a return to sports.

LEVEL OF EVIDENCE

Prospective case series, Level IV.

Editorial Commentary: Put Me Back Into The Game Coach! It's Time, I'm Ready: Time Is of No Essence After An Anterior Cruciate Ligament Reconstruction

Retear after an anterior cruciate ligament reconstruction is unavoidable. Many variables contribute to graft failure after anterior cruciate ligament reconstruction. Time from surgery to return to play is not the sole determinant. Graft maturation and symmetrical return of function need to be more carefully evaluated to reduce the risk of reinjury.

Length of Time Between Anterior Cruciate Ligament Reconstruction and Return to Sport Does Not Predict Need for Revision Surgery in National Football League Players

PURPOSE

To determine whether the length of time between primary anterior cruciate ligament reconstruction (ACLR) and return to sport (RTS) predicted the need for revision ACLR in National Football League (NFL) athletes.

METHODS

All NFL players who underwent ACLR from 2009 to 2015 were identified. The date of index ACLR and date of return to NFL regular-season game play after surgery were recorded. The length of time between ACLR and RTS was compared between players who required revision ACLR and those who did not. Correlation coefficients were used to assess whether players who RTS sooner sustained recurrent anterior cruciate ligament injury at an earlier date.

RESULTS

A total of 130 NFL players (average age, 25.3 ± 3.2 years) who underwent ACLR and returned to sport were identified. The average time to RTS after ACLR was 49.7 weeks after surgery. Of the players, 23 (18%) required revision ACLR. There was no significant difference in the length of time between ACLR and RTS in players who did not require revision ACLR (50.2 ± 10.1 weeks) and those who did (48.3 ± 11.0 weeks, P = .40). Time to RTS was not found to correlate with time to reinjury in athletes requiring revision ACLR (R = 0.21; 95% confidence interval, -0.18 to 0.54). A large proportion of players (56%) sustained a reinjury within the first 10 weeks of returning to NFL game play.

CONCLUSIONS

Our study found that timing of RTS after ACLR was not a significant risk factor for revision surgery in NFL athletes. Time to RTS was also not shown to correlate with time to reinjury.

LEVEL OF EVIDENCE

Level III, case-control study.

Hamstring tendon autografts do not show complete graft maturity 6 months postoperatively after anterior cruciate ligament reconstruction

PURPOSE

In this prospective, double-center cohort study, we aim to assess how the anterior cruciate ligament (ACL) signal intensity on magnetic resonance imaging (MRI) potentially varies between a group of patients with anatomic ACL reconstruction using autogenous hamstring grafts 6 months postoperatively and a healthy ACL control group, and how MRI-based graft signal intensity is related to knee laxity.

METHODS

Sixty-two consecutive patients who underwent ACL reconstruction using quadrupled hamstring tendon autograft were prospectively invited to participate in this study, and they were evaluated with MRI after 6 months of follow-up. 50 patients with an MRI of their healthy ACL (Clinica Luganese, Lugano, Switzerland) and 12 patients of their contralateral healthy knee (Department of Orthopaedic and Trauma Surgery, Medical University of Vienna, Austria) served as the control group. To evaluate graft maturity, the signal-to-noise quotient (SNQ) was measured in three regions of interest (ROIs) of the proximal, mid-substance and distal ACL graft and the healthy ACL. KT-1000 findings were obtained 6 months postoperatively in the ACL reconstruction group. Statistical analysis was independently performed to outline the differences in the two groups regarding ACL intensity and the correlation between SNQ and KT-1000 values.

RESULTS

There was a significant difference in the mean SNQ between the reconstructed ACL grafts and the healthy ACLs in the proximal and mid-substance regions (p = 0.001 and p = 0.004). The distal region of the reconstructed ACL showed a mean SNQ similar to the native ACL (n.s). Patients with a KT-1000 between 0 and 1 mm showed a mean SNQ of 0.1; however, a poor correlation was found between the mean SNQ and KT-1000 findings, probably due to the small sample size of patients with higher laxity.

CONCLUSION

After 6 months of follow-up, hamstring tendon autografts for anatomic ACL reconstruction do not show equal MRI signal intensity compared to a healthy ACL and should therefore be considered immature or at least not completely healed even if clinical laxity measurement provides good results. However, in the case of a competitive athlete, who is clinically stable and wants to return to sports at 6 months, performing an MRI to confirm the stage of graft healing might be an option.

LEVEL OF EVIDENCE

Prospective, comparative study II.

ACL reconstruction with hamstring tendon autograft and accelerated brace-free rehabilitation: a systematic review of clinical outcomes

OBJECTIVE

To investigate the clinical outcomes after hamstring tendon autograft ACL reconstruction (ACLR) with accelerated, brace-free rehabilitation.

DESIGN

Systematic review according to Preferred Reporting Items for Systematic Reviews and Meta-Analysis guidelines.

DATA SOURCES

Embase, MEDLINE Ovid, Web of Science, Cochrane CENTRAL and Google scholar from 1 January 1974 to 31 January 2017.

ELIGIBILITY CRITERIA FOR SELECTING STUDIES

Study designs reporting outcomes in adults after arthroscopic, primary ACLR with hamstring autograft and accelerated, brace-free rehabilitation.

RESULTS

Twenty-four studies were included in the review. The clinical outcomes after hamstring tendon autograft ACLR with accelerated brace-free rehabilitation were the following: (1) early start of open kinetic exercises at 4 weeks in a limited range of motion (ROM, 90°-45°) and progressive concentric and eccentric exercises from 12 weeks did not alter outcomes, (2) gender and age did not influence clinical outcomes, (3) anatomical reconstructions showed better results than non-anatomical reconstructions, (4) there was no difference between single-bundle and double-bundle reconstructions, (5) femoral and tibial tunnel widening occurred, (6) hamstring tendons regenerated after harvest and (7) biological knowledge did not support return to sports at 4-6 months.

CONCLUSIONS

After hamstring tendon autograft ACLR with accelerated brace-free rehabilitation, clinical outcome is similar after single-bundle and double-bundle ACLR. Early start of open kinetic exercises at 4 weeks in a limited ROM (90°-45°) and progressive concentric and eccentric exercises from 12 weeks postsurgery do not alter clinical outcome. Further research should focus on achievement of best balance between graft loading and graft healing in the various rehabilitation phases after ACLR as well as on validated, criterion-based assessments for safe return to sports.

LEVEL OF EVIDENCE

Level 2b; therapeutic outcome studies.

Autogenous Hamstring-Bone Graft Preparation for Anterior Cruciate Ligament Reconstruction

Despite the popularity of anterior cruciate ligament (ACL) reconstruction procedures, the ideal graft for reconstruction remains a matter of controversy. The ideal graft for ACL reconstruction should have histologic and biomechanical characteristics similar to those of the native ACL; should be quickly and fully incorporated within the bony tunnels; should maintain its viscoelastic properties for a long time; should have minimal donor-site morbidity; should be of sufficient length and diameter; should have minimal adverse effects on the extensor mechanism; should have no risk of rejection or disease transmission; and should be cost-effective and readily available. Synthetic grafts are not widely accepted because of their dangerous complications. The main sources of grafts for ACL reconstruction are allografts and autografts. Each type of graft has its own relative advantages and disadvantages. Allografts are not available in every country, besides being expensive, and there are many concerns regarding disease transmission. Autografts, particularly bone-patellar tendon-bone (BPTB), and hamstring tendon grafts have been the standard for ACL reconstruction. The main advantage of autogenous BPTB grafts is the direct bone-to-bone healing in the tunnel, whereas the main disadvantages of such grafts are related to donor-site morbidity, anterior knee pain, and extensor mechanism dysfunction. The popularity of autogenous hamstring tendon grafts for ACL reconstruction is increasing, but there are still concerns regarding the slow soft tissue-to-bone healing, with delayed healing and incorporation of the graft. We describe a technique for ACL reconstruction with autogenous hamstring-bone graft, aiming to produce a type of graft that combines the main advantages of BPTB and hamstring grafts, with avoidance of the main disadvantages of these 2 most commonly used graft types in ACL reconstruction.

Length of time between surgery and return to sport after ulnar collateral ligament reconstruction in Major League Baseball pitchers does not predict need for revision surgery

HYPOTHESIS

Pitchers who return to sport (RTS) sooner will have a higher risk of revision ulnar collateral ligament reconstruction (UCLR) than those who return later.

METHODS

All professional (major and minor league) baseball pitchers who underwent UCLR between 1974 and 2016 were identified. Date of the index UCLR was recorded. The date of the first game back at any professional level after surgery and the date the pitcher returned to the same level of play (if applicable) were recorded. Length of time between these dates was compared for pitchers who required a revision UCLR and those who did not.

RESULTS

Overall, 569 pitchers (average age, 24.8 ± 4.1 years) underwent UCLR and had reliable game logs after surgery. No statistically significant difference existed in the length of time to RTS at any professional level or at the same professional level between those pitchers who did not require a revision UCLR and those who did (P = .442, P = .238). Pitchers who required revision UCLR returned to any level of play almost 2 months earlier (14.7 vs. 16.5 months) and returned to the same level of play >2 months earlier (15.2 vs. 17.7 months) than matched controls who did not require revision UCLR, although this was not statistically significant (P = .179, P = .204).

CONCLUSION

No statistically significant difference existed in the length of time to RTS after UCLR in professional baseball players who required a revision UCLR and those who did not.

Relative individual workload changes may be a risk factor for rerupture of ulnar collateral ligament reconstruction

BACKGROUND

With an increasing number of Major League Baseball (MLB) players undergoing ulnar collateral ligament (UCL) reconstruction, there remains limited literature on appropriate post-reconstruction workload management to limit the risk of reinjury.

METHODS

A total of 28 MLB pitchers who underwent primary UCL reconstruction surgery and subsequently required revision reconstruction were identified and compared with 137 MLB pitchers who underwent primary reconstruction but did not later require revision surgery. Games pitched, pitch counts, and innings pitched were evaluated and compared 3 years before and after primary reconstruction. Results were then compared between groups.

RESULTS

Pitchers who later required revision increased their games pitched by 14.1% after reconstruction whereas the no-revision group pitched 13.6% fewer games than before reconstruction (P < .01). Inning workload was reduced by 9.8% after surgery (89.8 innings after vs 99.6 innings before) for the revision group compared with the no-revision group, which threw 26% fewer innings after surgery (86.3 innings after vs 116.7 innings before) (P = .05). In addition, the revision group pitched 6.6% more pitches after reconstruction, 1138.9 pitches, compared with before reconstruction, 1068.6 pitches. Pitchers who did not require revision, in contrast, pitched 19.6% fewer pitches after reconstruction than before reconstruction (P = .08).

CONCLUSIONS

This study's findings suggest that MLB pitchers who require revision UCL reconstruction after returning to play following primary UCL reconstruction pitch at or above their pre-primary UCL reconstruction workload whereas control pitchers who do not require revision pitch significantly less, below their pre-primary UCL reconstruction workload.

Does the tibial remnant of the anterior cruciate ligament promote ligamentization?

BACKGROUND

The purpose of this study was to clarify the difference in ligamentization between the remnant-preserving (RP) and remnant-sacrificing (RS) techniques in anterior cruciate ligament (ACL) reconstruction using magnetic resonance imaging (MRI).

METHODS

A retrospective comparative study was carried out on 98 patients undergoing ACL reconstruction using either an RP (n=56) or RS (n=42) technique. MRI was performed at one of four time points postoperatively, and the signal intensity of the ACL graft was analyzed using the signal to noise quotient (SNQ) ratio and inter-bundle high signal intensity, along with an analysis of the survival rate of remnant tissue.

RESULTS

The mean SNQ ratio of grafted tendons in the RP group was significantly higher than that seen in the RS group in the proximal and middle regions two to four months after surgery (P<0.05) and was significantly lower than that seen in the RS group in all regions at 12 -18months (P<0.05). The inter-bundle high signal intensity was observed more frequently in the RP group (73.7%) at two to four months. Tibial remnants were observed on postoperative MRI regardless of when MRI was conducted.

CONCLUSION

The ACL graft of the RP group showed higher signal intensity in the early stage and lower signal intensity in the late stage compared to that of the RS group. The ligamentization of grafts in the RP group proceeded more quickly. Preserving the remnant in ACL reconstruction appears to have a positive effect on ligamentization.

Patient-based decision for resuming activity after ACL reconstruction: a single-centre experience

PURPOSE

The purpose of the study was to report the functional outcome following anterior cruciate ligament (ACL) reconstruction in patients who decide when to resume work and normal sporting activity post-operatively. The hypothesis tested was that patient-based decision to return to work and sport was possible without compromising functional outcome and increased the rate of repeat rupture in comparison with the existing literature.

METHODS

This was a monocentric, retrospective study. Seventy-two patients requiring primary ACL reconstruction were included. All patients were followed up for a mean period of 4.3 years. Return to work and to sporting activity was allowed based on patient's decision. No restriction was suggested by the physician. Delays to return to work and sports and occurrence of graft failure were documented.

RESULTS

Sixty-six patients (92 %) returned to any sporting activity. The mean delay was 4.1 months for running, 6.1 months for pivoting sports, and 6.6 months for contact sports. Return to competitive sport was possible in 82 % of patients after a mean delay of 7.1 months. Return to work was possible for 96 % of patients after a mean delay of 2.3 months. Index Tegner score normalized in 71 % of patients. Four repeat ruptures (6 %) were observed, all of them following a significant knee injury.

CONCLUSIONS

Patient-based decision to return to work and sport was possible without compromising functional outcome. The post-operative restrictions implemented by orthopaedic surgeons following ACL reconstructions may be relaxed and more patient based.