"Biological failure” of the anterior cruciate ligament graft

Anterior cruciate ligament (ACL) reconstruction has the best chance for success when the graft undergoes extensive biologic remodeling and incorporation after implantation. There are many factors that can lead to graft failure and possible revision surgery. These include patient selection; surgical technique such as graft placement and tensioning; the use of allograft versus autograft; mechanical factors such as secondary restraint laxity; lack of a correct, carefully controlled post-operative rehabilitation program; and biological factors. When a patient presents with knee instability following ligament reconstruction and there is no history of a new trauma or identifiable technical error, biological failure should be considered. However, the biologic response of the grafted tissue is closely linked to the mechanical and biochemical environment into which the graft is placed. Thus, the "biological failure” of the ACL graft is a complex pathological entity whose cause is not fully understood. Failure may be initiated by early extensive graft necrosis, disturbances in revascularization, problems in cell repopulation and proliferation, and as well difficulties in the ligamentization process. However, further study of the biological characterization of a failed graft placed in a correct mechanical environment is warrante

A randomized controlled trial of PEEK versus titanium interference screws for anterior cruciate ligament reconstruction with 2-year follow-up

Purpose: To compare the clinical performance of ACL reconstruction with PEEK and titanium interference screws at 2 years and to evaluate a novel method of measuring tunnel volume. Study Design: Randomized controlled trial; Level of evidence, 1. Methods: A total of 133 patients underwent arthroscopic ACL reconstruction with 4-strand hamstring autografts and were randomized to have titanium or PEEK interference screws for femoral and tibial tunnel fixation. At 2 years, subjective Lysholm and International Knee Documentation Committee scores were assessed and clinical examination performed. At 12 months, MRI was performed to assess graft incorporation and cyst formation, and a novel technique was employed to measure tunnel volumes. Results: There were no significant differences in graft rerupture rate, contralateral ACL rupture rate, subjective outcomes, or objective outcomes. In the titanium and PEEK groups, MRI demonstrated high overall rates of graft integration (96%-100% and 90%-93%, respectively) and ligamentization (89% and 84%) and low rates of synovitis (22% and 10%) and cyst formation (0%-18% and 13%-15%). There was a higher proportion of patients with incomplete graft integration within the femoral tunnel in the PEEK group as compared with the titanium group (10% vs 0%, P = .03); however, the authors suggest that metal artifact precluded proper assessment of the graft in the titanium group by MRI. Tunnel volumes also appeared to be equivalent in the 2 groups and were measured with a novel technique that was highly reproducible in the PEEK group secondary to the absence of flare. Conclusion: Two-year clinical analysis of PEEK interference screws for femoral and tibial fixation of ACL reconstructions showed equivalent clinical performance to titanium interference screws. Given the excellent mechanical characteristics, biological compatibility, and absence of metal artifact on MRI, PEEK has become our material of choice for interference screw fixation in ACL reconstruction

Local Application of Strontium in a Calcium Phosphate Cement System Accelerates Healing of Soft Tissue Tendon Grafts in Anterior Cruciate Ligament Reconstruction: Experiment Using a Rabbit Model

Background: The healing of soft tissue tendon graft within the bone tunnel in anterior cruciate ligament (ACL) reconstruction is known to be slower than that of bone-patellar tendon-bone graft. There are attempts in accelerating the healing of the graft within the bone tunnel. One of the methods is the use of strontium-enriched calcium phosphate bone cement (Sr-CPC). The early result in animal study was encouraging, though it was not known whether the accelerated healing was solely due to the effect of the strontium within the cement, or due to the calcium phosphate cement (CPC) itself. Hypothesis: There would be differences between a strontium-enriched calcium phosphate cement (Sr-CPC) and a conventional calcium phosphate cement (CPC) in terms of the effect on soft tissue tendon graft healing within the bone tunnels in anterior cruciate ligament (ACL) reconstruction. Study Design: Controlled laboratory study. Methods: Thirty single bundle ACL reconstruction procedures were performed in 15 rabbits with the use of an Achilles tendon allograft. The graft on the left limb was coated with Sr-CPC, while that on the right limb was coated with CPC. Three animals were sacrificed for histological and histomorphometric analysis at 3, 6, 9, 12 and 24 weeks post-operation. Results: In the Sr-CPC group, early Sharpey fiber formation was present at 6 weeks post-operation while early remodeling of a graft-fibrocartilage-bone junction was noted at 12weeks. In the CPC group, early Sharpey fiber formation was only found at 9 to 12 weeks post-operation. At 24 weeks, a direct enthesis was found in both groups. According to histomorphometric score, graft healing in the Sr-CPC group took place 3 weeks faster than that in the CPC group at and before 12 weeks, but there was no difference at 24 weeks. Conclusion: The local application of strontium in a CPC system leads to accelerated graft healing within the bone tunnels. Clinical Relevance: The use of Sr-CPC to enhance graft-bone healing may improve the clinical results of ACL reconstruction using soft tissue tendon graft. Keywords: anterior cruciate ligament (ACL); strontium; calcium phosphate cementpostprin

Demineralized bone matrix to augment tendon-bone healing:a systematic review

BACKGROUND: Following injury to the rotator cuff and anterior cruciate ligament, a direct enthesis is not regenerated, and healing occurs with biomechanically inferior fibrous tissue. Demineralized bone matrix (DBM) is a collagen scaffold that contains growth factors and is a promising biological material for tendon and ligament repair because it can regenerate a direct fibrocartilaginous insertion via endochondral ossification. Purpose: To provide a comprehensive review of the literature investigating the use of DBM to augment tendon-bone healing in tendon repair and anterior cruciate ligament reconstruction (ACLR). Study Design: Systematic review. METHODS: Electronic databases (MEDLINE and EMBASE) were searched for preclinical and clinical studies that evaluated the use of DBM in tendon repair and ACLR. Search terms included the following: ("demineralized bone matrix" OR "demineralized cortical bone") AND ("tissue scaffold" OR "tissue engineering" OR "ligament" OR "tendon" OR "anterior cruciate ligament" OR "rotator cuff"). Peer-reviewed articles written in English were included, and no date restriction was applied (searches performed February 10, 2017). Methodological quality was assessed with peer-reviewed scoring criteria. RESULTS: The search strategy identified 339 articles. After removal of duplicates and screening according to inclusion criteria, 8 studies were included for full review (tendon repair, n = 4; ACLR, n = 4). No human clinical studies were identified. All 8 studies were preclinical animal studies with good methodological quality. Five studies compared DBM augmentation with non-DBM controls, of which 4 (80%) reported positive findings in terms of histological and biomechanical outcomes. CONCLUSION: Preclinical evidence indicates that DBM can improve tendon-bone healing, although clinical studies are lacking. A range of animal models of tendon repair and ACLR showed that DBM can re-create a direct fibrocartilaginous enthesis, although the animal models are not without limitations. Before clinical trials are justified, research is required that determines the best source of DBM (allogenic vs xenogenic) and the best form of DBM (demineralized cortical bone vs DBM paste) to be used in them

The vasculature and its role in the damaged and healing tendon

Tendon pathology has many manifestations, from spontaneous rupture to chronic tendinitis or tendinosis; the etiology and pathology of each are very different, and poorly understood. Tendon is a comparatively poorly vascularised tissue that relies heavily upon synovial fluid diffusion to provide nutrition. During tendon injury, as with damage to any tissue, there is a requirement for cell infiltration from the blood system to provide the necessary reparative factors for tissue healing. We describe in this review the response of the vasculature to tendon damage in a number of forms, and how and when the revascularisation or neovascularisation process occurs. We also include a section on the revascularisation of tendon during its use as a tendon graft in both ligament reconstruction and tendon–tendon grafting

Anterior cruciate ligament reconstruction with fresh-frozen patellar tendon allografts

A prospective study was performed on 30 patients who underwent an anterior cruciate ligament reconstruction with fresh-frozen patellar tendon allograft. An arthroscopic technique alone was used in 10 patients, and in the other 20 patients this was combined with a miniarthrotomy. After a mean follow up of 35 months, the overall functional results were satisfactory in 85%. There were no cases of infection, disease transmission or tissue rejection. Fresh-frozen patellar tendon allografts are a good method of anterior cruciate reconstruction

Anterior cruciate ligament reconstruction: A multicenter prospective cohort study evaluating 3 different grafts using same bone drilling method

To compare the clinical outcomes after anterior cruciate ligament (ACL) reconstruction with bone-patellar tendon-bone autograft (BPTBAu), BPTB allograft (BPTBAll), or hamstring (semitendinosus-gracilis) tendon autograft (HTAu), performing bone drilling with same methods in terms of transtibial drilling, orientation, positioning, and width of femoral and tibial tunnels. DESIGN: Multicenter prospective cohort study (level of evidence II). SETTING: Departments of Orthopedic Surgery of Centro Medico Teknon (Barcelona, Spain) Clinica Universitaria de Navarra (Navarra, Spain), and Clinica FREMAP (Gijon, Spain). PATIENTS: All patients with ACL tears attending 3 different institutions between January 2004 and June 2006 were approached for eligibility and those meeting inclusion criteria finally participated in this study. INTERVENTION: Each institution was assigned to perform a specific surgical technique. Patients were prospectively followed after undergoing ACL reconstruction with BPTBAu, BPTBAll, or HTAu, with a minimum follow-up of 24 months. MAIN OUTCOME MEASURES: Included knee laxity and International Knee Documentation Committee (IKDC) score. Knee laxity was assessed with the KT-1000 arthrometer (evaluated with neutral and external rotation positions) and both Lachman and pivot shift tests. Additional outcomes included main symptoms (anterior knee pain, swelling, crepitation, and instability), disturbance in knee sensation, visual analogue scale (VAS) for satisfaction with surgery, range of motion (ROM), and isokinetic knee strength. RESULTS: There were no significant differences among the 3 groups for any of the clinical outcomes, except for a slightly greater KT-1000-measured knee laxity in external rotation in the BPTBAu compared with the other groups. All patients demonstrated grade A or B of the IKDC. The mean VAS for satisfaction with surgery in all patients was 8.5. CONCLUSIONS: The selection of the surgical technique for ACL reconstruction may be based on the surgeon's preference

5-Year survival of pediatric anterior cruciate ligament reconstruction with living donor hamstring tendon grafts

Background: It is well accepted that there is a higher incidence of repeat anterior cruciate ligament (ACL) injuries in the pediatric population after ACL reconstruction (ACLR) with autograft tissue compared with adults. Hamstring autograft harvest may contribute to the risk for repeat ACL injuries in this high functional demand group. A novel method is the use of a living donor hamstring tendon (LDHT) graft from a parent; however, there is currently limited research on the outcomes of this technique, particularly beyond the short term. Purpose/Hypothesis: The purpose was to determine the medium-term survival of the ACL graft and the contralateral ACL (CACL) after primary ACLR with the use of an LDHT graft from a parent in those aged less than 18 years and to identify factors associated with subsequent ACL injuries. It was hypothesized that ACLR with the use of an LDHT provides acceptable midterm outcomes in pediatric patients. Study Design: Case series; Level of evidence, 4. Methods: Between 2005 and 2014, 247 (of 265 eligible) consecutive patients in a prospective database, having undergone primary ACLR with the use of an LDHT graft and aged less than 18 years, were included. Outcomes were assessed at a minimum of 2 years after surgery including data on ACL reinjuries, International Knee Documentation Committee (IKDC) scores, and current symptoms, as well as factors associated with the ACL reinjury risk were investigated. Results: Patients were reviewed at a mean of 4.5 years (range, 24-127 months [10.6 years]) after ACLR with an LDHT graft. Fifty-one patients (20.6%) sustained an ACL graft rupture, 28 patients (11.3%) sustained a CACL rupture, and 2 patients sustained both an ACL graft rupture and a CACL rupture (0.8%). Survival of the ACL graft was 89%, 82%, and 76% at 1, 2, and 5 years, respectively. Survival of the CACL was 99%, 94%, and 86% at 1, 2, and 5 years, respectively. Survival of the ACL graft was favorable in patients with Tanner stage 1-2 at the time of surgery versus those with Tanner stage 3-5 at 5 years (87% vs 69%, respectively; hazard ratio, 3.7; P = .01). The mean IKDC score was 91.7. A return to preinjury levels of activity was reported by 59.1%. Conclusion: After ACLR with an LDHT graft from a parent in those aged less than 18 years, a second ACL injury (ACL graft or CACL injury) occurred in 1 in 3 patients. The 5-year survival rate of the ACL graft was 76%, and the 5-year survival rate of the CACL was 86%. High IKDC scores and continued participation in sports were maintained over the medium term. Importantly, there was favorable survival of the ACL graft in patients with Tanner stage 1-2 compared with patients with Tanner stage 3-5 over 5 years. Patients with Tanner stage 1-2 also had a significantly lower incidence of second ACL injuries over 5 years compared with those with Tanner stage 3-5, occurring in 1 in 5 patients. Thus, an LDHT graft from a parent is an appropriate graft for physically immature children

El papel del plasma rico en plaquetas (PRP) en las lesiones deportivas de rodilla

El plasma rico en plaquetas (PRP) se está utilizando cada vez más. Usando como palabras clave “PRP” y “knee” (rodilla) se hizo una búsqueda en PubMed sobre el uso del PRP en las lesiones deportivas de la rodilla. Se encontraron 22 artículos. Muchos de ellos fueron estudios realizados en animales y el resto estudios sin grupo control llevados a cabo en humanos y publicados en revistas de rigor científico modesto. Dichos estudios animales y humanos sugieren que la colocación de un andamio en puente de colágeno-PRP en el defecto central del LCA podría estimular biomecánicamente e histológicamente su cicatrización. También que las inyecciones intra-articulares de PRP podrían mejorar la cicatrización de defectos meniscales. Por último, que las inyecciones de PRP podrían promover resultados satisfactorios en casos de rodilla de saltador (tendinitis rotuliana). Teniendo en cuenta la baja calidad de los datos publicados en la bibliografía y tras realizar una valoración objetiva del valor del PRP en las indicaciones previamente mencionadas, mi conclusión es que el PRP es todavía es un tratamiento experimental, que en muchos casos no ha demostrado tener un valor significativo en cuanto a sus efectosThe use of platelet-rich plasma (PRP) is becoming increasingly available. PubMed articles related to the use of PRP in sports injuries of the knee were searched using the following key words: PRP and knee. A total of 22 reports were found. Many of them were animal studies and the rest were human clinical studies with no controls and published in journals that do not expect as much rigour in the scientific validity. The aforementioned animal experiments and clinical studies suggest that placement of a collagen-PRP bridging scaffold in a central ACL defect can stimulate healing of the ACL histologically and biomechanically. Also that intra- articular injections of PRP can enhance the healing of meniscal defects. Finally, that PRP injections can have the potential to promote the achievement of a satisfactory clinical outcome in cases of jumper´s knee (patellar tendinopathy). Taking into account the low quality of the data reported in the literature and after performing an objective view of the value of PRP for the various indications, my conclusion is that PRP is a treatment that is still experimental and in many instances shown to be not significant in its effect