Anatomic single-bundle anterior cruciate ligament reconstruction using a calcium phosphate-hybridized tendon graft: a randomized controlled trial with 2 years of follow-up

[Research progress on bioactive strategies for promoting tendon graft healing after anterior cruciate ligament reconstruction]

Objective

To review the bioactive strategies that enhance tendon graft healing after anterior cruciate ligament reconstruction (ACLR), and to provide insights for improving the therapeutic outcomes of ACLR.

Methods

The domestic and foreign literature related to the bioactive strategies for promoting the healing of tendon grafts after ACLR was extensively reviewed and summarized.

Results

At present, there are several kinds of bioactive materials related to tendon graft healing after ACLR: growth factors, cells, biodegradable implants/tissue derivatives. By constructing a complex interface simulating the matrix, environment, and regulatory factors required for the growth of native anterior cruciate ligament (ACL), the growth of transplanted tendons is regulated at different levels, thus promoting the healing of tendon grafts. Although the effectiveness of ACLR has been significantly improved in most studies, most of them are still limited to the early stage of animal experiments, and there is still a long way to go from the real clinical promotion. In addition, limited by the current preparation technology, the bionics of the interface still stays at the micron and millimeter level, and tends to be morphological bionics, and the research on the signal mechanism pathway is still insufficient.

Conclusion

With the further study of ACL anatomy, development, and the improvement of preparation technology, the research of bioactive strategies to promote the healing of tendon grafts after ACLR is expected to be further promoted.

Anatomical Single-Bundle Anterior Cruciate Ligament Reconstruction Using a Calcium Phosphate-Hybridized Tendon Graft with More than an Average of 5 Years of Follow-Up: A Follow-Up Study of a Randomized Controlled Trial

Calcium phosphate (CaP)-hybridized tendon grafting using an alternate soaking process improves tendon-to-bone healing in anterior cruciate ligament (ACL) reconstructions. This study aimed to compare bone tunnel enlargement, knee osteoarthritis, and clinical results between CaP-hybridized tendon grafting and conventional grafting in anatomical single-bundle ACL reconstruction. This study was a follow-up of a randomized controlled trial. Between July 2011 and December 2015, 90 patients underwent unilateral anatomical single-bundle ACL reconstructions and were randomly assigned to the CaP-hybridized tendon grafting (CaP group, n = 45; age, 27.1 [14-54] years; sex, 21 males and 24 females) or conventional grafting (control group, n = 45; age, 22.9 [13-58] years; sex, 26 males and 19 females). The randomization was performed according to the days of the week when the patients first visited the outpatient. The CaP-hybridized tendon grafting was created intraoperatively. The tendon grafts were soaked in a calcium solution for 30 s. After that, the tendon grafts were soaked in a NaHPO4 solution for 30 s. This soaking cycle between the calcium solution and the NaHPO4 solution was repeated 10 times. The bone tunnel enlargement, osteoarthritis grade, clinical score, and sports level were evaluated in patients who could be followed up for >3 years (CaP group, n = 20, average follow-up period 6.0 [5.1-6.9] years; control group, n = 15, average follow-up period 5.6 [4.3-6.9] years). Clinical scores, sports levels, and osteoarthritis grades were analyzed using a generalized linear mixed model (GLMM) based on repeated measurement data from preoperative and final observations, with time, group, sex, age, and BMI as fixed effects and the effect of individual differences as variable effects. In addition, bone-tunnel enlargements were analyzed using generalized linear models (GLM) with group, sex, age, and BMI as the main effects. Compared with the control group, the CaP group exhibited significantly reduced bone-tunnel enlargement on the femoral side (anteroposterior diameter; CaP group, 7.9% [-1.1-16.8] vs. control group, 29.2% [17.9-40.5], p = 0.004, MCID 16.05, proximal-distal diameter; CaP group, 7.9% [-1.9-17.8] vs. control group, 22.8% [10.9-34.7], p = 0.062, MCID 15.00). The osteoarthritis grades progressed in both groups (p < 0.001). The clinical scores and sports levels were not significantly different between the groups. This study suggests that the calcium phosphate-hybridized tendon graft reduces femoral bone-tunnel enlargement after anatomical single-bundle anterior cruciate ligament reconstruction in an average >5-year follow-up period. A longer follow-up period is necessary to reveal the clinical effects of the calcium phosphate-hybridized tendon grafts in anterior cruciate ligament reconstruction.

Osteoinductive Bone Morphogenic Protein, Collagen Scaffold, Calcium Phosphate Cement, and Magnesium-Based Fixation Enhance Anterior Cruciate Ligament Tendon Graft to Bone Healing In Animal Models: A Systematic Review

PURPOSE

To perform a systematic literature review to analyze the results of the in vivo animal models and strategies that use osteoinductive materials to enhance the tendon graft-bone interface for anterior cruciate ligament reconstruction (ACLR).

METHODS

Following the Preferred Reporting Items for Systemic Reviews and Meta-Analysis guidelines, the PubMed, Embase, and Web of Science databases were searched. The inclusion criteria were studies of in vivo animal models of ACLR using a material to enhance tendon graft-bone interface healing and reporting at least the histologic results at the interface, along with radiologic and biomechanical data. Studies without control group or with another tendon-bone healing model were excluded. Methodologic quality was assessed with the Animal Research: Reporting In Vivo Experiments 1guidelines.

RESULTS

Twenty-seven studies met the inclusion criteria. Rabbit was the main animal model of ACLR, along with sheep and dog models. ACLR procedures varied widely between studies.. The main promising strategies and materials were wrapping the material around the graft, with a collagen scaffold loaded with an osteoinductive molecule (mostly bone morphogenetic proteins). The second strategy consisted of injecting the material at the tendon-bone interface; calcium phosphate cement or a derivative were the most used materials. Finally, using osteoinductive fixation devices was the third strategy; magnesium-based interference screws seemed to show most favorable results.

CONCLUSIONS

The studies retained had major methodologic flaws that limit the scope of these conclusions. However, based on histologic, biomechanical, and radiologic analyses, the most promising materials were a collagen scaffold loaded with an osteoinductive molecule and wrapped around the graft, calcium phosphate cement injected in the bone tunnel, and a magnesium-based fixation device.

CLINICAL RELEVANCE

In vivo animal models have identified several promising strategies and materials to optimize the tendon-bone interface after ACLR, but standardized and reproducible assessments are needed before these strategies can be adopted clinically.

Subjective assessment reported by patients shows differences between single-bundle and double-bundle anterior cruciate ligament reconstruction, systematic review and meta-analysis

To determine the functional recovery, active reincorporation, and anteroposterior and rotational stability of patients undergoing anterior cruciate ligament (ACL) reconstruction using arthroscopy techniques with simple-bundle (SB) or double-bundle (DB). The following databases were searched: PubMed, Embase (Elsevier platform), the Cochrane Central Register of Controlled Trials (Wiley platform), Web of Science, and CINAHL. Level I and II studies involving anterior cruciate ligament arthroscopy were included in the search. Records were screened by title and abstract and assessed the risk of bias of selected studies. Meta-analyses using RevMan 5.3 software were conducted on the following outcomes: knee functionality, objective measurements of knee stability, rotational knee stability and knee anterior stability, sports reincorporation, and subjective assessments. Twenty-four studies of patients undergoing ACL reconstruction were included in the qualitative and quantitative synthesis (1707 patients) for Lysholm score, Subjective International Knee Documentation Committee (IKDC) score, Tegner score, KT-1000/2000, Lachman test, Objective IKDC score, and Pivot-Shift test. A return to pre-injury level showed a significant decrease in the Lysholm score (mean difference, - 0.99; 95% CI - 1.71 to - 0.40; P = 0.007) and Tegner score (mean difference, - 0.07; 95% CI, - 0.13 to - 0.01; P = 0.02) at DB reconstruction, similar to the knee functionality outcome of the subjective IKDC score (mean difference - 1.42; 95% CI - 2.46 to - 0.38; P = 0.007). There is no clear or significant difference in clinical stability and knee function or in sports incorporation with the true difference occurring in the subjective assessment.

Biological fixation between calcium phosphate-hybridized tendon graft and tibial bone tunnel in anatomic single-bundle ACL reconstruction - A case report

The purpose of this study was to histologically observe a specimen of a calcium phosphate (CaP)-hybridized tendon graft-bone interface at the posterior side of tibial bone tunnel obtained during the revision anterior cruciate ligament (ACL) reconstruction. We present the case of a 15-year-old female who was returning to sports 7 months and 12 days after primary anatomic single-bundle ACL reconstruction with no instability. Re-rupture was diagnosed 9 months and 12 days after the surgery. At the joint aperture site, a firm biological fixation via direct bonding area, cartilaginous tissue, and dense collagen fiber were observed without the presence of a nonbonding gap area.

Safety and feasibility of using calcium phosphate hybridization method for quadriceps tendon-bone graft in anterior cruciate ligament reconstruction

Background

To improve tendon-to-bone healing in anterior cruciate ligament (ACL) reconstruction, a novel technique via the calcium phosphate (CaP) hybridization method for tendon graft using an alternate soaking process was developed. The use of the CaP hybridization method for quadriceps tendon-bone (QTB) graft in ACL reconstruction has not been reported in previous studies. Thus, this clinical trial aimed to clarify the safety and feasibility of using CaP hybridization method for quadriceps tendon-bone (QTB) graft in ACL reconstruction.

Methods

Eight patients (average age, 41.6 ± 10.6 years; 2 men and 6 women) with unilateral ACL injury were included in this study. They underwent ACL reconstruction using QTB graft that hybridized CaP. The follow-up period was from 2 months to 4 years (average, 2.4 ± 1.5 years). Cases of adverse events, including tumor formation, infection, fracture, contracture, severe pain, and re-rupture, were recorded. Moreover, clinical results (KT-1000 arthrometry, pivot-shift test, International Knee Documentation Committee grade, Lysholm scale, and sports activity level), and images of graft and bone tunnel (magnetic resonance imaging, arthroscopic appearance, and computed tomography) were also evaluated.

Results

No adverse events were observed in the follow-up periods. Postoperative clinical results showed improvement compared with the preoperative findings. The sports activity level after the surgery became equivalent to that before injury. There was no progression of bone tunnel enlargement.

Conclusions

Using the CaP hybridization method for QTB graft in ACL reconstruction was safe and feasible in the clinical trial. Moreover, this method may improve clinical outcomes. In the future, it is necessary to verify the effect of the CaP hybridization method for QTB graft in ACL reconstruction.