Bridge-enhanced Anterior Cruciate Ligament Repair Research Articles

Comprehensive evaluation of magnetic resonance imaging sequences for signal intensity based assessment of anterior cruciate ligament healing following surgical treatment.

Normalized signal intensity (SI) obtained from magnetic resonance imaging (MRI) has been used to track anterior cruciate ligament (ACL) postoperative remodeling. We aimed to assess the effect of MRI sequence (PD: proton density-weighted; T2: T2-weighted; CISS: constructive interference in steady state) on postoperative changes in healing ACLs/grafts. We hypothesized that CISS is better at detecting longitudinal SI and texture changes of the healing ACL/graft compared to the common clinical sequences (PD and T2). MR images of patients who underwent ACL surgery were evaluated and separated into groups based on surgical procedure (Bridge-Enhanced ACL Repair (BEAR; n = 50) versus ACL reconstruction (ACLR; n = 24)). CISS images showed decreasing SI across all timepoints in both the BEAR and ACLR groups (p < 0.01), PD and T2 images showed decreasing SI in the 6-to-12- and 12-to-24-month postoperative timeframes in the BEAR group (p < 0.02), and PD images additionally showed decreasing SI between 6- and 24-months postoperation in the ACLR group (p = 0.02). CISS images showed texture changes in both the BEAR and ACLR groups, showing increases in energy and decreases in entropy in the 6-to-12- and 6-to-24-month postoperative timeframes in the BEAR group (p 0.04), and increases in energy, decreases in entropy, and increases in homogeneity between 6 and 24 months postoperation in the ACLR group (p < 0.04). PD images showed increases in energy and decreases in entropy between 6- and 24-months postoperation in the ACLR group (p < 0.008). Finally, CISS was estimated to require a smaller sample size than PD and T2 to detect SI differences related to postoperative remodeling.

An Isolated Midsubstance ACL Tear Repaired With the BEAR System

Background: Anterior cruciate ligament (ACL) repairs, once widely abandoned due to historically high failure rates, have recently regained interest with the development of the bridge-enhanced ACL repair (BEAR) implant, a novel arthroscopic technique that uses a resorbable protein-based implant combined with autologous blood to primarily repair a midsubstance ACL tear. This technical note presents a step-by-step surgical method for performing an isolated midsubstance ACL repair using the BEAR implant. Indications: The BEAR implant is indicated for skeletally mature patients at least 14 years of age with a complete rupture of the ACL, confirmed by magnetic resonance imaging. The complete ACL tear must have an attached stump to the tibia. Technique Description: A diagnostic arthroscopy is used to confirm complete rupture of the ACL and presence of residual tibial stump. A self-retrieving suture passage device is used to whipstitch a total of 6 passes with #2 Vicryl suture from distal to proximal through the residual stump. A notchplasty followed by femoral and tibial tunnels is created in a standard fashion. An Endobutton, soaked in a bacitracin solution, is then loaded with the sutures that were previously passed through the residual ACL stump and then through the femoral tunnel and cinched down to bone. The 4 suture ends that are coming from the Endobutton are then passed through the BEAR implant with the use of a Keith needle and shuttled through the tibial tunnel. The BEAR implant is hydrated with 15 cc of the patient's blood and is shuttled through the anteromedial portal with the knee in full extension. The 4 tibial sutures passed through the graft and tibial tunnel are passed, and tensioned to the proximal tibial with a second Endobutton. Standard closure and dressings are applied. Results: This new surgical implant and technique have shown noninferiority to ACL autograft reconstruction with respect to the International Knee Documentation Committee and anteroposterior laxity, with improved hamstring strength and decreased incidence of contralateral ACL tears at 2 years postoperative. Discussion/Conclusion: While initial data remain promising, future long-term designed studies are needed to determine the clinical efficacy of the BEAR technique, particularly comparing itself with bone-patellar tendon-bone autograft ACL reconstruction. Patient Consent Disclosure Statement: The author(s) attests that consent has been obtained from any patient(s) appearing in this publication. If the individual may be identifiable, the author(s) has included a statement of release or other written form of approval from the patient(s) with this submission for publication.

Treatment of Sports Injuries in Orthopedic Surgery: Recent Advances

This article reviews the most recent advances in the literature regarding orthopedic surgery for sports injuries. For large-to-massive rotator cuff tears, non-surgical treatment yielded superior results at three months to surgical treatment, although surgical treatment provided better results over time. Arthroscopic partial repair without a posterior interval slide yielded superior results to complete arthroscopic rotator cuff repair with a posterior interval slide. Graft bridging yielded superior results to superior capsular reconstruction. In first-time shoulder dislocations, arthroscopic Bankart repair has yielded superior results to arthroscopic washout. In high-grade acromioclavicular separation, a single clavicle tunnel tendon graft construct is preferable to a double tunnel construct. In femoroacetabular impingement, patients treated with hip arthroscopy had superior short-term results to those treated with physiotherapy alone. The odds of needing anterior cruciate ligament (ACL) graft revision were 2.1-fold higher for patients using a hamstring autograft than those using a patellar bone-tendon-bone (BTB) autograft. The use of a patellar tendon graft reduced the risk of graft rupture. The return-to-sports rate was higher for patients who underwent surgery with a BTB autograft than those with an autograft hamstring. The combination of lateral extra-articular tenodesis and ACL reconstruction-ACLR (single-bundle hamstring autograft) decreased the risk of ACLR failure after two years of follow-up. In complete mid-substance ACL injuries, the bridge-enhanced ACL repair technique resulted in similar outcomes to autograft ACLR. Fresh-frozen allografts have been a good alternative to autografts in ACLR. In posterior medial meniscal root tears, root repair was associated with less arthritic progression than non-surgical treatment and partial meniscectomy. Medial patellofemoral ligament (MPFL) reconstruction has provided better results than MPFL repair in patellofemoral instability.

Bridge enhanced ACL repair vs. ACL reconstruction for ACL tears: A systematic review and meta-analysis of comparative studies.

Anterior cruciate ligament (ACL) tear is one of the most frequent ligamentous injuries. The gold standard for ACL tears is autograft reconstruction. However, ACL repair has regained enthusiasm with more recent results showing comparable outcomes to its reconstructive counterpart. PubMed, Cochrane, and Google Scholar (pp. 1-20) were searched until November 2022. The clinical outcomes consisted of the International Knee Documentation Committee (IKDC) score, Knee Injury and Osteoarthritis Outcome Score (KOOS), the side-to-side difference in Anteroposterior (AP) knee laxity, the forces of the hamstring, quadriceps, and hip abduction as well as hopping tests. Only two studies were included in this meta-analysis. ACL repair was shown to have better Hamstrings strength. The rest of the analyzed outcomes were comparable. This is the first meta-analysis comparing these two treatments. The ACL repair showed no differences in muscle strength (quadriceps and hip abductors), postoperative knee scores, and knee joint laxity when compared to ACL reconstruction. However, it showed better hamstring strength. Further randomized clinical studies will be needed to compare both of these techniques.

Bridge-Enhanced Anterior Cruciate Ligament Repair for Mid-Substance Tear With Concomitant Lateral Meniscus Radial Repair

In recent years, repair of the injured anterior cruciate ligament (ACL) has been subject to a renewed interest as novel arthroscopic techniques have been developed. Specifically, the bridge-enhanced ACL repair is a technique composed of a resorbable protein-based implant combined with autologous blood that is used to bridge the gap between 2 torn edges of a mid-substance ACL tear. This implant is believed to help facilitate healing of a primary suture repair and suture cinch and has since demonstrated noninferiority to ACL reconstruction with autograft at 2-year follow-up. The purpose of this Technical Note is to describe a step-by-step surgical technique of a mid-substance ACL repair using the bridge-enhanced ACL repair system in a case with a concomitant lateral meniscus radial repair

Trends in Anterior Cruciate Ligament Repair: A Bibliometric and Visualized Analysis.

Bibliometrics is a methodology that measures the scientific output of an author, institution, or country. Visualized analysis is the transformation of data into visible form by software, highlighting important features, including commonalities and anomalies, allowing users to easily and quickly perceive significant aspects of their data. To conduct a bibliometric analysis of the literature on anterior cruciate ligament (ACL) repair, with visualization of trends, in order to identify the areas of interest and the primary researchers involved in ACL repair. Cross-sectional study. The PubMed database was queried on April 14, 2022, for publications that reported on ACL repair from 1960 onward. The initial search resulted in 1392 publications. Filter settings were applied to remove publications with weak correlation, such as those on meniscal repair and ACL reconstruction. Publication information, citations, authors, commonly used terms, and affiliated institutions and countries were analyzed by VOSviewer and Python. A total of 553 articles were included for analysis. Three techniques were visualized: bridge-enhanced ACL repair, internal brace, and dynamic intraligamentary stabilization. The most published authors were Martha Murray (51 articles), Gregory Difelice (35 articles), and Braden Fleming (31 articles). The most cited article was "Collagen-Platelet Rich Plasma Hydrogel Enhances Primary Repair of the Porcine Anterior Cruciate Ligament" by Murray et al. The journals with the most publications on ACL repair were the American Journal of Sports Medicine (n = 49); Knee Surgery, Sports Traumatology, Arthroscopy (n = 49); and Arthroscopy (n = 48). The top 3 institutions by publication number were the Hospital for Special Surgery (n = 51), Boston Children's Hospital (n = 49), and Brown University (n = 31), with the most publications coming from the United States (n = 242), Germany (n = 83), and the United Kingdom (n = 47). The results demonstrate that the research on ACL repair comes from a small number of authors and corresponding institutions; the top sports medicine journals and the developed countries have an interest in this topic.

Earlier Resolution of Symptoms and Return of Function After Bridge-Enhanced Anterior Cruciate Ligament Repair As Compared With Anterior Cruciate Ligament Reconstruction.

Background:Bridge-enhanced anterior cruciate ligament repair (BEAR) has noninferior patient-reported outcomes when compared with autograft anterior cruciate ligament reconstruction (ACLR) at 2 years. However, the comparison of BEAR and autograft ACLR at earlier time points—including important outcomes such as resolution of knee pain and symptoms, recovery of strength, and return to sport—has not yet been reported.Hypothesis:It was hypothesized that the BEAR group would have higher outcomes on the International Knee Documentation Committee and Knee injury and Osteoarthritis Outcome Score, as well as improved muscle strength, in the early postoperative period.Study Design:Randomized controlled trial; Level of evidence, 1.Methods:A total of 100 patients aged 13 to 35 years with complete midsubstance anterior cruciate ligament injuries were randomized to receive a suture repair augmented with an extracellular matrix implant (n = 65) or an autograft ACLR (n = 35). Outcomes were assessed at time points up to 2 years postoperatively. Mixed-model repeated-measures analyses were used to compare BEAR and ACLR outcomes. Patients were unblinded after their 2-year visit.Results:Repeated-measures testing revealed a significant effect of group on the International Knee Documentation Committee Subjective Score (P = .015), most pronounced at 6 months after surgery (BEAR = 86 points vs ACLR = 78 points; P = .001). There was a significant effect of group on the Knee injury and Osteoarthritis Outcome Score-Symptoms subscale scores (P = .010), largely attributed to the higher BEAR scores at the 1-year postoperative time point (88 vs 82; P = .009). The effect of group on hamstring strength was significant in the repeated-measures analysis (P < .001), as well as at all postoperative time points (P < .001 for all comparisons). At 1 year after surgery, approximately 88% of the patients in the BEAR group and 76% of the ACLR group had been cleared for return to sport (P = .261).Conclusion:Patients undergoing the BEAR procedure had earlier resolution of symptoms and increased satisfaction about their knee function, as well as improved resolution of hamstring muscle strength throughout the 2-year follow-up period.Registration:NCT02664545 (ClinicalTrials.gov identifier)

Bridge-Enhanced Anterior Cruciate Ligament Repair Leads to Greater Limb Asymmetry and Less Cartilage Damage Than Untreated ACL Transection or ACL Reconstruction in the Porcine Model

Background: The extent of posttraumatic osteoarthritis (PTOA) in the porcine anterior cruciate ligament (ACL) transection model is dependent on the surgical treatment selected. In a previous study, animals treated with bridge-enhanced ACL repair using a tissue-engineered implant developed less PTOA than those treated with ACL reconstruction (ACLR). Alterations in gait, including asymmetric weightbearing and shorter stance times, have been noted in clinical studies of subjects with osteoarthritis. Hypothesis: Animals receiving a surgical treatment that results in less PTOA (ie, bridge-enhanced ACL repair) would exhibit fewer longitudinal postoperative gait asymmetries over a 1-year period when compared with treatments that result in greater PTOA (ie, ACLR and ACL transection). Study Design: Controlled laboratory study. Methods: Thirty-six Yucatan minipigs underwent ACL transection and were randomized to receive (1) no further treatment, (2) ACLR, or (3) bridge-enhanced ACL repair. Gait analyses were performed preoperatively, and at 4, 12, 26, and 52 weeks postoperatively. Macroscopic cartilage assessments were performed at 52 weeks. Results: Knees treated with bridge-enhanced ACL repair had less macroscopic damage in the medial tibial plateau than those treated with ACLR or ACL transection (adjusted P = .03 for both comparisons). The knees treated with bridge-enhanced ACL repair had greater asymmetry in hindlimb maximum force and impulse loading at 52 weeks than the knees treated with ACL transection (adjusted P < .05 for both comparisons). Although not significant, there was a trend that knees treated with bridge-enhanced ACL repair had greater asymmetry in hindlimb maximum force and impulse loading (adjusted P < .10 for both comparisons) compared with ACLR. Conclusion: Contrary to our hypothesis, the surgical treatment resulting in less macroscopic cartilage damage (ie, bridge-enhanced ACL repair) exhibited greater asymmetry in load-related gait parameters than the other surgical groups. This finding suggests that increased offloading of the surgical knee may be associated with a slower rate of PTOA development. Clinical Relevance: Less cartilage damage at 52 weeks was found in the surgical group that continued to protect the limb from full body weight during gait. This finding suggests that protection of the knee from maximum stresses may be important in minimizing the development of PTOA in the ACL-injured knee within 1 year.

Interrater Agreement of an Arthroscopic Anterior Cruciate Ligament Tear Classification System.

Background:Anterior cruciate ligament (ACL) rupture is the most common ligament injury treated surgically by orthopaedic surgeons. The gold standard for the treatment of the majority of primary ACL tears is ACL reconstruction. However, novel methods of repair, such as bridge-enhanced ACL repair (BEAR), are currently being investigated as alternatives to reconstruction. To assess patients for midsubstance repair suitability, clarify the prognostic implications of injury location and damage, and evaluate the results of a repair technique, it is important to have a baseline classification system or grading scale that is reproducible across surgeons, particularly for multicenter collaboration. Currently, no such system or scale exists.Purpose:To develop an arthroscopic ACL tear classification system and to evaluate its interobserver reliability.Study Design:Cohort study (diagnosis); Level of evidence, 3.Methods:Eleven fellowship-trained orthopaedic surgeon investigators reviewed 75 video clips containing arthroscopic evaluation of a torn ACL and then completed the 6-question ACL Pathology Evaluation Form. Agreement statistics including exact agreement, Fleiss κ, Gwet agreement coefficient 1 (AC1), and Gwet AC2 were then calculated to assess interobserver reliability.Results:In aggregate, the multiple assessments of observer reproducibility revealed that surgeon participants in this study, when evaluating the same injury, agreed roughly 80% of the time on whether (1) at least 50% of the tibial footprint remained, (2) the remaining tibial stump was ≥10 mm, and (3) the injury was therefore reparable using the BEAR procedure. Participants also agreed roughly 60% of the time on exactly how many suturable bundles were available. These characteristics are believed to be most important, among those studied, in determining whether a torn ACL is amenable to midsubstance repair.Conclusion:This study is the first of its kind to demonstrate the interobserver reliability of arthroscopic classification of ACL tears. We have demonstrated that this classification system, though not ideally reproducible, is reliable enough across surgeons at multiple institutions for use in multicenter studies.Registration:NCT03776162 (ClinicalTrials.gov identifier).

Higher Physiologic Platelet Counts in Whole Blood Are Not Associated With Improved ACL Cross-sectional Area or Signal Intensity 6 Months After Bridge-Enhanced ACL Repair.

Background:A bridge-enhanced anterior cruciate ligament (ACL) repair (BEAR) procedure places an extracellular matrix implant, combined with autologous whole blood, in the gap between the torn ends of the ligament at the time of suture repair to stimulate healing. Prior studies have suggested that white blood cell (WBC) and platelet concentrations significantly affect the healing of other musculoskeletal tissues.Purpose/Hypothesis:The purpose of this study was to determine whether concentrations of various blood cell types placed into a bridging extracellular matrix implant at the time of ACL repair would have a significant effect on the healing ligament cross-sectional area or tissue organization (as measured by signal intensity). We hypothesized that patients with higher physiologic platelet and lower WBC counts would have improved healing of the ACL on magnetic resonance imaging (MRI) (higher cross-sectional area and/or lower signal intensity) 6 months after surgery.Study Design:Cohort study; Level of evidence, 2.Methods:A total of 61 patients underwent MRI at 6 months after bridge-enhanced ACL repair as part of the BEAR II trial. The normalized signal intensity and average cross-sectional area of the healing ligament were measured from a magnetic resonance stack obtained using a gradient echo sequence. The results were stratified by sex, and univariate and multivariate regression analyses determined significant correlations between blood cell concentrations on these 2 magnetic resonance parameters.Results:In unadjusted analyses, older age and male sex were associated with greater healing ligament cross-sectional area (P < .04) but not signal intensity (P > .15). Adjusted multivariable analyses indicated that in female patients, a higher monocyte concentration correlated with a higher ACL cross-sectional area (β = 1.01; P = .049). All other factors measured, including the physiologic concentration of platelets, neutrophils, lymphocytes, basophils, and immunoglobulin against bovine gelatin, were not significantly associated with either magnetic resonance parameter in either sex (P > .05 for all).Conclusion:Although older age, male sex, and monocyte concentration in female patients were associated with greater healing ligament cross-sectional area, signal intensity of the healing ligament was independent of these factors. Physiologic platelet concentration did not have any significant effect on cross-sectional area or signal intensity of the healing ACL at 6 months after bridge-enhanced ACL repair in this cohort. Given these findings, factors other than the physiologic platelet concentration and total WBC concentration may be more important in the rate and amount of ACL healing after bridge-enhanced ACL repair.

O’Donoghue Sports Injury Award: Bridge-Enhanced ACL Repair is Non-Inferior to Autograft ACL Reconstruction at 2-Years: Results of a Prospective Randomized Clinical Trial

Objectives:Preclinical studies and an early clinical cohort study have suggested that for complete midsubstance ACL injuries, the technique of suture repair of the anterior cruciate ligament (ACL) augmented with a protein implant placed in the gap between the torn ends (bridge-enhanced ACL repair) may be a viable alternative to ACL reconstruction. We hypothesized that patients treated with bridge-enhanced ACL repair would have non-inferior patient reported outcomes and anteroposterior (AP) laxity, and superior hamstring strength at 2 years after surgery when compared with subjects who had ACL reconstruction with autograft.Study Design:Prospective Randomized Control Trial (NCT02664545).Methods:One hundred patients, ages 13 to 35, with complete mid-substance ACL injuries, were enrolled and underwent surgery within 45 days of injury. Sixty-five patients were randomized to receive a bridge-enhanced ACL repair (BEAR group) and 35 were randomized to receive autograft ACL reconstruction (ACLR group). Outcomes, including the International Knee Documentation Committee (IKDC) Subjective score, instrumented AP laxity and muscle strength were assessed at 2 years post-operatively. Both patients and assessors were blinded as to surgical assignment until after the 2-year assessment.Results:Ninety-six percent of the subjects returned for follow-up at 2 years. The median age of the subjects in both groups at enrollment was 17 years and the median pre-operative Marx score in both groups was 16 points. Non-inferiority criteria were met for both the IKDC subjective score and AP laxity. The BEAR group had significantly better recovery of hamstring strength than the ACLR group (p<0.001). The number of subjects who were reinjured and required a second ACL surgery was not statistically different between the two groups. Subjects who converted from BEAR to ACLR in the study period had outcomes at the 2-year point that were similar to those for subjects who had only a single ipsiateral ACL procedure (BEAR or ACLR).Conclusion:Bridge-enhanced ACL repair using a specific protein-based implant led to non-inferior outcomes to that of ACL reconstruction for patient reported and instrumented knee laxity measures at 2 years after surgery in a young and active cohort of patients with acute mid-substance ACL tears.

Females Have Earlier Muscle Strength and Functional Recovery After Bridge-Enhanced Anterior Cruciate Ligament Repair.

Background: While a sex effect on outcomes following anterior cruciate ligament (ACL) reconstruction surgery has been previously documented, less is known following bridge-enhanced ACL repair (BEAR). We hypothesized that female sex would have significantly worse early functional outcomes and higher retear rates following primary repair of the ACL enhanced with a tissue-engineered scaffold. Methods: Sixty-five patients (28 males and 37 females), age 14-35 with a complete ACL tear underwent primary repair of the ACL enhanced with a tissue-engineered scaffold (bridge-enhanced ACL repair) within 45 days of injury. International Knee Documentation Committee (IKDC) and Knee Injury and Osteoarthritis Outcome (KOOS) scores, as well as instrumented anteroposterior (AP) laxity through KT-1000 testing and functional outcome measures were obtained at time points up to 2 years postoperatively and compared between males and females using mixed model repeated measures analyses and chi square tests. Results: There was no significant sex difference on the postoperative IKDC Subjective Score at 3, 6, 12, or 24 months or any of the five KOOS scores at 12 and 24 months. Instrumented AP laxity testing demonstrated mean (standard deviation) side-to-side differences that were similar in the two sexes at 2 years; 1.7 (2.7) mm and 1.5 (3.7) mm in females and males, respectively, p = 0.72. At 6 months postoperatively, males had a larger deficit in hamstring strength on the operated leg (14.0% vs. 1.7%; p = 0.03) and a larger deficit in quadriceps strength on the operated leg (11.3% vs. 2.0%; p = 0.004); however, no sex difference was noted at 12 or 24 months. Females demonstrated superior single leg hop testing at 6 and 12 months ([91.3% vs. 78.1%, p = 0.001], [96.9% vs. 87.0%, p = 0.01] respectively). There were no significant sex differences on ipsilateral (males; 14.3% vs. females; 13.9%, p = 1.00) or contralateral (males; 3.6% vs. females; 2.8%, p = 1.00) ACL reinjury rates. Conclusions: Female subjects had better hamstring and quadriceps strength indices at 6 months than males as well as better hop test results at the 6 and 12-month time period. Despite this, there was no significant sex difference on patient-reported outcomes and objective AP laxity testing at time points up to 2 years postoperatively. Impact statement This is the first study comparing sex specific outcomes following the bridge-enhanced ACL repair technique (BEAR). The results of this study suggest that females have earlier recovery of both muscle strength and functional outcomes compared to their male counterparts. This is an important finding when considering future modifications to postoperative care and rehabilitation in females and males following this tissue-engineered BEAR technique.

Resolution of Pain and Predictors of Postoperative Opioid use after Bridge-Enhanced Anterior Cruciate Ligament Repair and Anterior Cruciate Ligament Reconstruction

PurposeTo compare postoperative pain scores and opioid use between patients undergoing a standard arthroscopic anterior cruciate ligament reconstruction (ACLR) using hamstring autograft with those undergoing a suture repair augmented with an extracellular matrix scaffold (bridge-enhanced ACL repair) performed through an arthrotomy and to determine factors predictive of postoperative opioid use and levels of overprescription.MethodsA nonrandomized controlled trial was conducted with 20 patients (10 ACLR, 10 bridge-enhanced ACL repair), aged 18 to 35 years. All surgeries were performed by a single surgeon. A pain medication log was provided to patients on discharge. No regional anesthesia was performed. Pain scores via a visual analog pain scale were recorded at each visit. Correlations between preoperative and intraoperative characteristics and postoperative opioid use were determined.ResultsThe total morphine-equivalent dose ranged from 30 to 309 mg (4-42 pills oxycodone) for the ACLR group and 75 to 254 mg (10-34 pills oxycodone) for the bridge-enhanced ACL repair group. The average opioid use per day was 35.8 mg for the patients undergoing bridge-enhanced ACL repair and 44.2 mg for patients undergoing ACLR (P = .29). Pain scores at time points up to 2 years postoperatively were not significantly different between the 2 groups. Across both groups, the average oversupply of oxycodone was 46 pills per patient, a greater than 70% unused opiate rate. Preoperative body mass index and preoperative Knee Injury and Osteoarthritis Outcome Scores pain score were predictive of greater postoperative opioid use per day, whereas age, concurrent meniscal repair, and operative time were not.ConclusionsTotal overall opiate intake was not different between the patients undergoing bridge-enhanced ACL repair through an arthrotomy and those undergoing arthroscopic ACLR. Both groups had similar pain scores from 2 weeks to 2 years postoperatively. Greater body mass index and greater preoperative pain (lower Knee Injury and Osteoarthritis Outcome Scores pain score) correlated with greater postoperative opioid use per day. There was an overprescription of opioids across all patients.Level of EvidenceLevel III, case control study (therapeutic).

Bridge-Enhanced Anterior Cruciate Ligament Repair Is Not Inferior to Autograft Anterior Cruciate Ligament Reconstruction at 2 Years: Results of a Prospective Randomized Clinical Trial

Background: Preclinical studies suggest that for complete midsubstance anterior cruciate ligament (ACL) injuries, a suture repair of the ACL augmented with a protein implant placed in the gap between the torn ends (bridge-enhanced ACL repair [BEAR]) may be a viable alternative to ACL reconstruction (ACLR). Hypothesis: We hypothesized that patients treated with BEAR would have a noninferior patient-reported outcomes (International Knee Documentation Committee [IKDC] Subjective Score; prespecified noninferiority margin, –11.5 points) and instrumented anteroposterior (AP) knee laxity (prespecified noninferiority margin, +2-mm side-to-side difference) and superior muscle strength at 2 years after surgery when compared with patients who underwent ACLR with autograft. Study Design: Randomized controlled trial; Level of evidence, 1. Methods: One hundred patients (median age, 17 years; median preoperative Marx activity score, 16) with complete midsubstance ACL injuries were enrolled and underwent surgery within 45 days of injury. Patients were randomly assigned to receive either BEAR (n = 65) or autograft ACLR (n = 35 [33 with quadrupled semitendinosus-gracilis and 2 with bone–patellar tendon–bone]). Outcomes—including the IKDC Subjective Score, the side-to-side difference in instrumented AP knee laxity, and muscle strength—were assessed at 2 years by an independent examiner blinded to the procedure. Patients were unblinded after their 2-year visit. Results: In total, 96% of the patients returned for 2-year follow-up. Noninferiority criteria were met for both the IKDC Subjective Score (BEAR, 88.9 points; ACLR, 84.8 points; mean difference, 4.1 points [95% CI, –1.5 to 9.7]) and the side-to-side difference in AP knee laxity (BEAR, 1.61 mm; ACLR, 1.77 mm; mean difference, –0.15 mm [95% CI, –1.48 to 1.17]). The BEAR group had a significantly higher mean hamstring muscle strength index than the ACLR group at 2 years (98.2% vs 63.2%; P < .001). In addition, 14% of the BEAR group and 6% of the ACLR group had a reinjury that required a second ipsilateral ACL surgical procedure (P = .32). Furthermore, the 8 patients who converted from BEAR to ACLR in the study period and returned for the 2-year postoperative visit had similar primary outcomes to patients who had a single ipsilateral ACL procedure. Conclusion: BEAR resulted in noninferior patient-reported outcomes and AP knee laxity and superior hamstring muscle strength when compared with autograft ACLR at 2-year follow-up in a young and active cohort. These promising results suggest that longer-term studies of this technique are justified. Registration: NCT02664545 (ClinicalTrials.gov identifier)

Changes in Cross-Sectional Area and Signal Intensity of Healing ACLs and ACL Grafts in the First Two Years After Surgery

Objectives: The quality of a repaired anterior cruciate ligament (ACL) or reconstructed graft is typically quantified by evaluating knee, lower extremity or subject performance. However, magnetic resonance (MR) imaging of the healing ACL or graft provides a more direct measure of the tissue quality (i.e., signal intensity) and quantity (i.e., cross-sectional area). Here we used a quantitative MR imaging approach to evaluate longitudinal changes in graft size and signal intensity over the first 2 years after ACL reconstruction (ACLR). We also studied the structural changes in ACLs treated with a novel surgical repair procedure, Bridge-Enhanced ACL Repair (BEAR). We hypothesized that there would be differences in the cross-sectional area or signal intensity of the repaired ACL or reconstructed graft within 2 years after surgery, and that these structural properties correlate with knee anatomy. Methods: MR images of the patients recruited in the BEAR first-in-human trial (10 BEAR and 10 ACLR) were used to measure ACL/graft cross-sectional area and signal intensity at 3, 6, 12 and 24 months. ACL stump length, posterior slope of the medial and lateral tibial plateau, maximum depth of the medial tibial plateau, and sagittal ACL/graft elevation angle and femoral notch width were also measured from MRI. Notchplasty was defined as the difference between the post- and preoperative notch width. Results: Cross-sectional area of the grafts was 48-98% larger than the contralateral intact ACL at all time points (p&lt;.01). The BEAR ACLs were 23-28% greater than the contralateral intact ACL at 3 and 6 months (p&lt;.02), but similar at 12 and 24 months (Fig 1A). Both the BEAR and ACLR groups had a slightly higher signal intensity (indicative of lower tissue quality) at 3 months compared to the contralateral intact ACL, which then trended to a maximum at 6 months before reduction to the levels seen in the contralateral intact ACL at 24 months (p&gt;.1; Fig 1B). The BEAR ACL had the same sagittal elevation angle as the contralateral intact ACL and coursed from insertion site to insertion site rather than from the femoral to tibial tunnel. The ACLR grafts coursed from tibial to femoral tunnels and were 6.5 º more vertical (p=.005) than the contralateral intact ACL. For the BEAR ACLs, the bigger notch correlated with bigger cross-sectional area, while a shorter ACL femoral stump, steeper lateral tibial slope and shallower medial tibial depth were associated with higher signal intensity (R2&gt;.40; p&lt;.05). Performance of notchplasty resulted in increased ACL cross-sectional area after BEAR procedure (p=.007; Fig 1). No anatomic features were correlated with ACL graft size or signal intensity. Conclusion: ACLR grafts continue to remodel over the first 2 years after surgery, whereas the remodeling of ACLs treated with the BEAR procedure occur predominantly in the first year. The BEAR procedure more closely restores the cross-sectional area and orientation in the sagittal plane than an ACL graft placed using a transtibial technique. The cross-sectional area of the repaired ACLs may be increased by performing a notchplasty at the time of surgery. [Figure: see text]

Changes in Cross-sectional Area and Signal Intensity of Healing Anterior Cruciate Ligaments and Grafts in the First 2 Years After Surgery

Background: The quality of a repaired anterior cruciate ligament (ACL) or reconstructed graft is typically quantified in clinical studies by evaluating knee, lower extremity, or patient performance. However, magnetic resonance imaging of the healing ACL or graft may provide a more direct measure of tissue quality (ie, signal intensity) and quantity (ie, cross-sectional area). Hypotheses: (1) Average cross-sectional area or signal intensity of a healing ACL after bridge-enhanced ACL repair (BEAR) or a hamstring autograft (ACL reconstruction) will change postoperatively from 3 to 24 months. (2) The average cross-sectional area and signal intensity of the healing ligament or graft will correlate with anatomic features of the knee associated with ACL injury. Study Design: Cohort study; Level of evidence, 2. Methods: Patients with a complete midsubstance ACL tear who were treated with either BEAR (n = 10) or ACL reconstruction (n = 10) underwent magnetic resonance imaging at 3, 6, 12, and 24 months after surgery. Images were analyzed to determine the average cross-sectional area and signal intensity of the ACL or graft at each time point. ACL orientation, stump length, and bony anatomy were also assessed. Results: Mean cross-sectional area of the grafts was 48% to 98% larger than the contralateral intact ACLs at all time points (P < .01). The BEAR ACLs were 23% to 28% greater in cross-sectional area than the contralateral intact ACLs at 3 and 6 months (P < .02) but similar at 12 and 24 months. The BEAR ACLs were similar in sagittal orientation to the contralateral ACLs, while the grafts were 6.5° more vertical (P = .005). For the BEAR ACLs, a bigger notch correlated with a bigger cross-sectional area, while a shorter ACL femoral stump, steeper lateral tibial slope, and shallower medial tibial depth were associated with higher signal intensity (R2 > .40, P < .05). Performance of notchplasty resulted in an increased ACL cross-sectional area after the BEAR procedure (P = .007). No anatomic features were correlated with ACL graft size or signal intensity. Conclusion: Hamstring autografts were larger in cross-sectional area and more vertically oriented than the native ACLs at 24 months after surgery. BEAR ACLs had a cross-sectional area, signal intensity, and sagittal orientation similar to the contralateral ACLs at 24 months. The early signal intensity and cross-sectional area of the repaired ACL may be affected by specific anatomic features, including lateral tibial slope and notch width—observations that deserve further study in a larger cohort of patients. Registration: NCT02292004 (ClinicalTrials.gov identifier)

Predictors of Healing Ligament Size and Magnetic Resonance Signal Intensity at 6 Months After Bridge-Enhanced Anterior Cruciate Ligament Repair

Background: Primary repair of the anterior cruciate ligament (ACL) augmented with a tissue engineered scaffold to facilitate ligament healing is a technique under development for patients with ACL injuries. The size (the amount of tissue) and signal intensity (the quality of tissue) of the healing ligament as visualized on magnetic resonance imaging (MRI) have been shown to be related to its strength in large animal models. Hypothesis: Both modifiable and nonmodifiable risk factors could influence the size and signal intensity of the repaired ligament in patients at 6 months after surgery. Study Design: Case series; Level of evidence, 4. Methods: 62 patients (mean age, 19.4 years; range, 14-35 years) underwent MRI of the knee 6 months after ACL repair augmented with an extracellular matrix scaffold. The signal intensity (normalized to cortical bone) and average cross-sectional area of the healing ligament were measured from the MRI stack obtained by use of a gradient echo sequence. Associations between these 2 measures and patient characteristics, which included demographic, clinical, and anatomic features, were determined by use of multivariable regression analysis. Results: A larger cross-sectional area of the repaired ligament at 6 months was associated with male sex, older age, and the performance of a larger notchplasty (P < .05 for all associations). A lower signal intensity at 6 months, indicating greater similarity to normal ligament, was associated with a smaller tibial slope and greater side-to-side difference in quadriceps strength 3 months after surgery. Other factors, including preoperative body mass index, mechanism of injury, tibial stump length, and Marx activity score, were not significantly associated with either MRI parameter at 6 months. Conclusion: Modifiable factors, including surgical notchplasty and slower recovery of quadriceps strength at 3 months, were associated with a larger cross-sectional area and improved signal intensity of the healing ACL after bridge-enhanced ACL repair in this preliminary study. Further studies to determine the optimal size of the notchplasty and the most effective postoperative rehabilitation strategy after ACL repair augmented by a scaffold are justified. Registration: NCT02664545 (ClinicalTrials.gov identifier).

Bridge-Enhanced Anterior Cruciate Ligament Repair: Two-Year Results of a First-in-Human Study.

Background:Bridge-enhanced anterior cruciate ligament repair (BEAR) combines suture repair of the anterior cruciate ligament (ACL) with a specific extracellular matrix scaffold (the BEAR scaffold) that is placed in the gap between the torn ends of the ACL to facilitate ligament healing.Purpose/Hypothesis:The purpose of this study was to report the 12- and 24-month outcomes of patients who underwent the BEAR procedure compared with a nonrandomized concurrent control group who underwent ACL reconstruction (ACLR) with an autograft. We hypothesized that the BEAR group would have physical examination findings, patient-reported outcomes, and adverse events that were similar to those of the ACLR group.Study Design:Cohort study; Level of evidence, 2.Methods:Ten patients underwent BEAR, and 10 underwent ACLR with a 4-stranded hamstring autograft. At 24 months, 9 of the 10 BEAR patients and 7 of the 10 ACLR patients completed a study visit. Outcomes reported included International Knee Documentation Committee (IKDC) subjective and objective results, knee anteroposterior (AP) laxity findings via an arthrometer, and functional outcomes.Results:There were no graft or repair failures in the first 24 months after surgery. The IKDC subjective scores in both groups improved significantly from baseline (P < .0001) at 12 and 24 months, to 84.6 ± 17.2 in the ACLR group and to 91.7 ± 11.7 in the BEAR group. An IKDC objective grade of A (normal) was found in 44% of patients in the BEAR group and in 29% of patients in the ACLR group at 24 months; no patients in either group had C (abnormal) or D (severely abnormal) grades. Arthrometer testing demonstrated mean side-to-side differences in AP laxity that were similar in the 2 groups at 24 months (BEAR, 1.94 ± 2.08 mm; ACLR, 3.14 ± 2.66 mm). Functional hop testing results were similar in the 2 groups at 12 and 24 months after surgery. Hamstring strength indices were significantly higher in the BEAR group compared with the ACLR group (P = .0001).Conclusion:In this small, first-in-human study, BEAR produced similar outcomes to ACLR with a hamstring autograft. BEAR may result in knee stability and patient-reported outcomes at 2 years sufficient to warrant longer term studies of efficacy in larger groups of patients.

Bridge-Enhanced ACL Repair: Two Year Results of the First In Human Study

Objectives: The Bridge-Enhanced ACL Repair (BEAR) procedure is an alternate form of anterior cruciate ligament (ACL) surgery that involves suture repair of the ligament combined with a scaffold to bridge the gap between the torn ligament ends. In this paper, we report outcomes of this procedure and a non-randomized concurrent control group receiving ACL reconstruction with quadrupled hamstring tendon autograft. We hypothesized that patients treated with Bridge-Enhanced ACL Repair would have physical exam findings, patient reported outcomes and adverse events at one and two years that were similar to patients treated with ACL reconstruction. Methods: This was an observational cohort study. Twenty patients were enrolled. Ten patients received a Bridge-Enhanced ACL Repair (BEAR®) and 10 received a hamstring autograft ACL reconstruction. Outcomes were assessed at time points up to 2 years post-operatively, including the International Knee Documentation Committee (IKDC) Subjective Score, the IKDC Objective score, KT-1000 testing for AP laxity and functional testing. Results: There were no graft or repair failures in the first two years after surgery. The IKDC Subjective Scores in both groups improved significantly from baseline (p&lt; 0.0001) but were similar in BEAR and ACL reconstruction groups at 12 and 24 months. An IKDC Objective score of A (normal) was found in 44% of the patients in the BEAR group and 29% of the patients in the ACL reconstruction group at two years; no patients in either group had a grade of C (abnormal) or D (severely abnormal). KT-1000 testing demonstrated a side to side difference that was similar in the two groups at 2 years (mean(±SD) 1.9(± 2.1) mm in the BEAR group, 3.1(± 2.7) mm in the ACLR group). Functional hop testing results were similar in the two groups at 1 and 2 years after surgery. Hamstring strength indices measured by dynamometer were significantly higher at all time points in the BEAR group than in the hamstring autograft group (mean percentages relative to contralateral side at two years, 98.6%(±10.5%) vs 56.3%(±19.0%), p=0.0001). Conclusion: In a small first-in-human study, Bridge-Enhanced ACL Repair produced similar outcomes to ACL reconstruction with autograft quadruple bundle hamstring tendon.

Synovial fluid proteome changes in ACL injury-induced posttraumatic osteoarthritis: Proteomics analysis of porcine knee synovial fluid.

Surgical transection of the anterior cruciate ligament (ACL) in the porcine model leads to posttraumatic osteoarthritis if left untreated. However, a recently developed surgical treatment, bridge-enhanced ACL repair, prevents further cartilage damage. Since the synovial fluid bathes all the intrinsic structures of knee, we reasoned that a comparative analysis of synovial fluid protein contents could help to better understand the observed chondroprotective effects of the bridge-enhanced ACL repair. We hypothesized that post-surgical changes in the synovial fluid proteome would be different in the untreated and repaired knees, and those changes would correlate with the degree of cartilage damage. Thirty adolescent Yucatan mini-pigs underwent unilateral ACL transection and were randomly assigned to either no further treatment (ACLT, n = 14) or bridge-enhanced ACL repair (BEAR, n = 16). We used an isotopically labeled high resolution LC MS/MS-based proteomics approach to analyze the protein profile of synovial fluid at 6 and 12 months after ACL transection in untreated and repaired porcine knees. A linear mixed effect model was used to compare the normalized protein abundance levels between the groups at each time point. Bivariate linear regression analyses were used to assess the correlations between the macroscopic cartilage damage (total lesion area) and normalized abundance levels of each of the identified secreted proteins. There were no significant differences in cartilage lesion area or quantitative abundance levels of the secreted proteins between the ACLT and BEAR groups at 6 months. However, by 12 months, greater cartilage damage was seen in the ACLT group compared to the BEAR group (p = 0.005). This damage was accompanied by differences in the abundance levels of secreted proteins, with higher levels of Vitamin K-dependent protein C (p = 0.001), and lower levels of Apolipoprotein A4 (p = 0.021) and Cartilage intermediate layer protein 1 (p = 0.049) in the ACLT group compared to the BEAR group. There were also group differences in the secreted proteins that significantly changed in abundance between 6 and 12 months in ACLT and BEAR knees. Increased concentration of Ig lambda-1 chain C regions and decreased concentration of Hemopexin, Clusterin, Coagulation factor 12 and Cartilage intermediate layer protein 1 were associated with greater cartilage lesion area. In general, ACLT knees had higher concentrations of pro-inflammatory proteins and lower concentrations of anti-inflammatory proteins than BEAR group. In addition, the ACLT group had a lower and declining synovial concentrations of CILP, in contrast to a consistently high abundance of CILP in repaired knees. These differences suggest that the knees treated with bridge-enhanced ACL repair may be maintaining an environment that is more protective of the extracellular matrix, a function which is not seen in the ACLT knees.