Adverse events associated with biodegradable lactide-containing suture anchors

Engineering Musculoskeletal Grafts for Multi-Tissue Unit Repair: Lessons From Developmental Biology and Wound Healing

In the musculoskeletal system, bone, tendon, and skeletal muscle integrate and act coordinately as a single multi-tissue unit to facilitate body movement. The development, integration, and maturation of these essential components and their response to injury are vital for conferring efficient locomotion. The highly integrated nature of these components is evident under disease conditions, where rotator cuff tears at the bone-tendon interface have been reported to be associated with distal pathological alterations such as skeletal muscle degeneration and bone loss. To successfully treat musculoskeletal injuries and diseases, it is important to gain deep understanding of the development, integration and maturation of these musculoskeletal tissues along with their interfaces as well as the impact of inflammation on musculoskeletal healing and graft integration. This review highlights the current knowledge of developmental biology and wound healing in the bone-tendon-muscle multi-tissue unit and perspectives of what can be learnt from these biological and pathological processes within the context of musculoskeletal tissue engineering and regenerative medicine. Integrating these knowledge and perspectives can serve as guiding principles to inform the development and engineering of musculoskeletal grafts and other tissue engineering strategies to address challenging musculoskeletal injuries and diseases.

Engineering multi-tissue units for regenerative Medicine: Bone-tendon-muscle units of the rotator cuff

Our body systems are comprised of numerous multi-tissue units. For the musculoskeletal system, one of the predominant functional units is comprised of bone, tendon/ligament, and muscle tissues working in tandem to facilitate locomotion. To successfully treat musculoskeletal injuries and diseases, critical consideration and thoughtful integration of clinical, biological, and engineering aspects are necessary to achieve translational bench-to-bedside research. In particular, identifying ideal biomaterial design specifications, understanding prior and recent tissue engineering advances, and judicious application of biomaterial and fabrication technologies will be crucial for addressing current clinical challenges in engineering multi-tissue units. Using rotator cuff tears as an example, insights relevant for engineering a bone-tendon-muscle multi-tissue unit are presented. This review highlights the tissue engineering strategies for musculoskeletal repair and regeneration with implications for other bone-tendon-muscle units, their derivatives, and analogous non-musculoskeletal tissue structures.

Clinical and radiological outcomes with PEEK suture anchors used in rotator cuff repair: our experience confirm that a perianchor fluid signal on RM does not affect clinical outcome at one year of follow up

Introduction / objectives:

Osteolytic-type reactions of the perianchor bone which in magnetic resonance are manifested as hyperintensity of the signal in T2 images are reported in many studies. The doubt that this reaction of the bone could result in a loss of pull-out in the short and medium term and that it could therefore negatively affect tendon healing is the subject of an increasing number of studies. An osteolytic type signal around absorbable anchors can be explained by the metabilic processes in progress foreseen by the very nature of the material used, however this type of signal is also recognized around sutured implants or made of notoriously inert material. The objective of the present study is to evaluate and compare to the literature data the clinical and radiological results of a group of patients who underwent arthroscopic suture of a rotator cuff tear using polyetherketone (PEEK) suture anchors.

Materials and methods:

Twenty patients, aged between 44 and 73 years, who underwent arthroscopic repair of the rotator cuff for lesions smaller than 4 cm considered reparaible between August 2017 and January 2019, were enrolled in the present study. Patients were evaluated clinically with clinical examination, Constant scale and ASES scale pre and post surgery. MRI either pre and post operation at one year were evaluated to obtain data about tendon healing and evaluate bone reaction to PEEK anchors.

Results:

The mean lesion size was 16.8 mm +/- 7.8 mm and the mean tendon retraction was 15.6 mm +/- 14.9 mm. The mean increase in Constant and ASES scores at the one year-follow up was respectively 36.8 (p<0.01) and 47.2 (p<0.01). MRI analysis showed a tendon signal according to Sugaya classification of type 1 in the 25% of patients, type 2 in the 60% of cases and type 3 in the remaining 15% . Osteolysis was grade 0 in 65%, grade 1 in 30 % and grade 2 in 5% of cases. No anchors pull out or mobilization were reported.

Conclusions:

The presence of a T2 hyperintense signal osteolysis like on MRI control using PEEK anchors for the sutur of rotator cuff lesions does not find correlation whit the final clinical result of the procedure. Indeed, both patients with a major degree of osteolysis and those with degree 0 had an improvement both in terms of clinical and scores evaluation and in termsof tendon healing according to Sugaya’s score found in our cohort. (www.actabiomedica.it)

In vivo osseointegration and erosion of nacre screws in an animal model

The use of resorbable devices for osteosynthesis has become a subject of interest. Nacre has been proposed as a resorbable and osteoconductive material favoring bone apposition without triggering an inflammatory reaction. We compared the in vivo osseointegration and erosion of nacre screws in an animal model with titanium screws. Implantation of similar nacre and titanium screws was performed in the femoral condyles of adult rats. Animals (n = 41) were randomized in four groups sacrificed at day one, 1, 6, and 12 months. Microcomputed tomography (microCT) allowed 3D morphometry of erosion of nacre. Osseointegration was measured as the volume of trabecular bone bone volume/tissue volume (BV/TV) in a standardized volume of interest around each screw. Undecalcified bone histology was also done. Gross examination revealed a similar clinical osseointegration for titanium and nacre screws. A progressive erosion of nacre screws, but no erosion of titanium screws, was observed in microCT. The volume of nacre screws progressively decreased over time whereas no modification occurred for titanium. For titanium screws, BV/TV remained stable throughout the study. For nacre screws, the BV/TV decrease was not statistically different. A significant difference was found between nacre and titanium screws at 6 months but not at 12 months. The screw heads, outside the bone shaft, were not eroded even after 12 months. Erosion of nacre occurred during the entire study period, only within the bone shaft in direct contact with bone marrow. Bone apposition was observed on nacre surfaces without signs of erosion. Nacre is a promising biomaterial in maxillofacial surgery.

The five year outcome of a clinical feasibility study using a biphasic construct with minced autologous cartilage to repair osteochondral defects in the knee

PURPOSE

Autologous minced cartilage has been used to repair cartilage defects. We have developed a biphasic cylindrical osteochondral construct for such use in human knees, and report the five year post-operative outcomes.

METHODS

Ten patients with symptomatic osteochondral lesion at femoral condyles were treated by replacing pathological tissue with the osteochondral composites, each consisted a _DL-poly-lactide-co-glycolide chondral phase and a _DL-poly-lactide-co-glycolide/β-tricalcium phosphate osseous phase. A flat chamber between the two phases served as a reservoir to house double-minced (mechanical pulverization and enzymatical dissociation) autologous cartilage graft. The osteochondral lesion was drill-fashioned a pit of identical dimensions as the construct. Graft-laden construct was press fit to the pit. Post-operative outcome was evaluated using Knee Injury and Osteoarthritis Outcome Score (KOOS) up to five years. Regenerated tissue was sampled with arthroscopic needle biopsy for histology at one year, and imaged with magnetic resonance at one, three, and five years to evaluate the neocartilage with MOCART chart. Subchondral bone integration was evaluated with computed tomography at three and five years.

RESULTS

Nine patients completed the five-year follow-up. Post-operative mean KOOS, except that of the "symptom" subscale, had been significantly higher than pre-operation from one year and maintained to five years. The change of MOCRAT scores of the regenerated cartilage paralleled the change of KOOS. The osseous phase remained mineralized during the five-year period, yet did not fully integrate with the host bone.

CONCLUSIONS

This novel construct for chondrocyte implantation yielded promising mid-term outcome. It repaired the osteochondral lesion with hyaline-like cartilage durable for at least five years.

Bony Ingrowth of Coil-Type Open-Architecture Anchors Compared With Screw-Type PEEK Anchors for the Medial Row in Rotator Cuff Repair: A Randomized Controlled Trial

PURPOSE

To evaluate outcomes of screw-type and coil-type open-architecture suture anchors with respect to bony ingrowth, release of biological markers, and patient-reported outcome measures when used in rotator cuff repair (RCR).

METHODS

Forty patients undergoing arthroscopic RCR for full-thickness rotator cuff tears were enrolled and prospectively randomized to receive a screw-type (19 patients) or coil-type (21 patients) suture anchor for the medial row during repair. All repairs used a transosseous-equivalent configuration with footprint anchors laterally. Marrow elements released during surgery were evaluated for 9 cytokine markers (insulin-like growth factor 1, fibroblast growth factor 2, bone morphogenetic proteins 7 and 2, platelet-derived growth factors AA and BB, epidermal growth factor, transforming growth factor beta1, and vascular endothelial growth factor). Postoperative computed tomography scans were performed at 6 months. Range of motion, strength, and validated patient-reported outcome measures (Simple Shoulder Test, Single Assessment Numeric Evaluation, visual analog scale, and American Shoulder and Elbow Surgeons scores) were gathered before the operation and at 6 months and 1 year postoperatively.

RESULTS

Bone mineral density surrounding the coil-type anchor was significantly greater than that surrounding the screw-type anchor (P = .005). Bone mineral density values within the coil-type and screw-type anchors were comparable (P = .527); however, a larger amount of total bone mineral mass (in milligrams) was shown within the coil-type anchor owing to its larger volume (P < .01). Marrow elements released at the repair site were similar between groups (P > .05). Postoperatively, no statistically significant difference was found between groups for clinical outcome measures at 6 months or 1 year. Retear and complication rates were similar between groups (P > .05).

CONCLUSIONS

Both the coil-type and screw-type anchors can be reliably used for RCR and produce similar clinical outcomes. The coil-type anchor resulted in superior bony growth surrounding the anchor and a larger total bone mineral mass within the anchor owing to its larger volume.

LEVEL OF EVIDENCE

Level II, randomized prospective comparative study.

Long-term study on the osteogenetic capability and mechanical behavior of a new resorbable biocomposite anchor in a canine model

Background

Biodegradable suture anchors are commonly used for repairing torn rotator cuffs, but these biodegradable materials still suffer from low mechanical strength, poor osteointegration, and the generation of acidic degradation byproducts.

Method

The purpose of this study was to evaluate the long-term mechanical behavior and osteogenetic capabilities of a biocomposite anchor injection molded with 30% β-tricalcium phosphate microparticles blended with 70% poly (L-lactide-co-glycolide) (85/15). This study investigated in vitro degradation and in vivo bone formation in a canine model. The initial mechanical behavior, mechanical strength retention with degradation time, and degradation features were investigated.

Results

The results showed that the biocomposite anchor had sufficient initial mechanical stability confirmed by comparing the initial shear load on the anchor with the minimum shear load borne by an ankle fracture fixation screw, which is considered a worst-case implantation site for mechanical loading. The maximum shear load retention of the biocomposite anchor was 83% at 12 weeks, which is desirable, as it aligns with the rate of bone healing. The β-tricalcium phosphate fillers were evenly dispersed in the polymeric matrix and acted to slow the degradation rate and improve the mechanical strength of the anchor. The interface characteristics between the β-tricalcium phosphate particles and the polymeric matrix changed the degradation behavior of the biocomposite. Phosphate buffer saline was shown to diffuse through the interface into the biocomposite to inhibit the core accelerated degradation rate. In vivo, the addition of β-tricalcium phosphate induced new bone formation. The biocomposite material developed in this study demonstrated improved osteogenesis in comparison to a plain poly (L-lactide-co-glycolide) material. Neither anchor produced adverse tissue reactions, indicating that the biocomposite had favorable biocompatibility following long-term implantation.

Conclusion

In summary, the new biocomposite anchor presented in this study had favorable osteogenetic capability, mechanical property, and controlled degradation rate for bone fixation.

Translational potential of this article

The new biocomposite anchor had sufficient initial and long-term fixation stability and bone formation capability in the canine model. It is indicated that the new biocomposite anchor has a ​potential for orthopedic application.

Changes in Perianchor Cyst Formation Over Time After Rotator Cuff Repair: Influential Factors and Outcomes

BACKGROUND

There is a lack of knowledge about the changes in perianchor cysts over time and the factors related to perianchor cysts.

PURPOSE

To evaluate the changes in perianchor cyst formation and anchor absorption over time after arthroscopic rotator cuff repair with a biocomposite suture anchor and to evaluate the factors affecting perianchor cyst persistence and their relationship with patient outcomes.

STUDY DESIGN

Case-control study; Level of evidence, 3.

METHODS

Forty consecutive patients (mean age, 61.10 ± 5.79 years) who underwent arthroscopic repair for medium- to large-sized rotator cuff tears using a single type of biocomposite (poly-L-lactic acid/polyglycolic acid-beta tricalcium phosphate) medial-row anchor were prospectively enrolled. Postoperative magnetic resonance imaging (MRI) at 2 different time points (6 and 18 months) was performed, and perianchor cyst formation, anchor absorption, and healing failures were evaluated using postoperative MRI. Demographic and clinical data were collected, and functional outcomes at a minimum of 18 months after surgery were assessed.

RESULTS

Perianchor cysts were observed in 24 patients (60.0% total; grade 1: 35.0%; grade 2: 10.0%; grade 3: 7.5%; grade 4: 7.5%) at 6 months, and 7 patients (18.4% total; grade 1: 7.9%; grade 2: 5.3%; grade 3: 2.6%; grade 4: 2.6%) had a persistent perianchor cyst at 18 months after surgery. No anchors were absorbed at 6 months, but 73.7% of patients revealed complete or near-full absorption at 18 months. Patients with persistent perianchor cysts showed a significantly larger tear size in the anteroposterior dimension ( P = .002) and greater retraction ( P < .001). There were no differences in healing failures and functional outcomes between patients with and without persisting perianchor cysts (all P > .05). No differences were found in perianchor cyst formation and anchor absorption between anchors inserted in the greater tuberosity and the lesser tuberosity (all P > .05).

CONCLUSION

The incidence and severity of perianchor cysts decreased with time, and most biocomposite suture anchors were absorbed at 18 months after surgery. Persisting perianchor cysts correlated with a larger tear size in the anteroposterior dimension and greater retraction.

The Aging Face

The aging face is a popular topic in modern medicine. To understand and treat unwanted signs of aging, it is imperative to understand the biological and physical causes and contributing factors to facial aging, preventative measures to avoid advanced facial aging, and current treatment options. Changes to the human face are progressive with time; however, there are many methods, both surgical and nonsurgical, to reduce the stigmata of aging and provide patients with the appearance they desire. The process of aging is discussed in this article, as well as the multiple treatment options, both surgical and nonsurgical.

Functionally Graded, Bone- and Tendon-Like Polyurethane for Rotator Cuff Repair

Critical considerations in engineering biomaterials for rotator cuff repair include bone-tendon-like mechanical properties to support physiological loading and biophysicochemical attributes that stabilize the repair site over the long-term. In this study, UV-crosslinkable polyurethane based on quadrol (Q), hexamethylene diisocyante (H), and methacrylic anhydride (M; QHM polymers), which are free of solvent, catalyst, and photoinitiator, is developed. Mechanical characterization studies demonstrate that QHM polymers possesses phototunable bone- and tendon-like tensile and compressive properties (12-74 MPa tensile strength, 0.6-2.7 GPa tensile modulus, 58-121 MPa compressive strength, and 1.5-3.0 GPa compressive modulus), including the capability to withstand 10 000 cycles of physiological tensile loading and reduce stress concentrations via stiffness gradients. Biophysicochemical studies demonstrate that QHM polymers have clinically favorable attributes vital to rotator cuff repair stability, including slow degradation profiles (5-30% mass loss after 8 weeks) with little-to-no cytotoxicity in vitro, exceptional suture retention ex vivo (2.79-3.56-fold less suture migration relative to a clinically available graft), and competent tensile properties (similar ultimate load but higher normalized tensile stiffness relative to a clinically available graft) as well as good biocompatibility for augmenting rat supraspinatus tendon repair in vivo. This work demonstrates functionally graded, bone-tendon-like biomaterials for interfacial tissue engineering.

Biocomposite Implants Composed of Poly(Lactide-co-Glycolide)/β-Tricalcium Phosphate: Systematic Review of Imaging, Complication, and Performance Outcomes

PURPOSE

To determine the degradation and performance outcomes of poly(lactide-co-glycolide)/β-tricalcium phosphate (PLGA/β-TCP) implants.

METHODS

A MEDLINE and Embase search for randomized or nonrandomized controlled studies and prospective or retrospective case series that used biocomposite interference screws or suture anchors composed of PLGA/β-TCP was performed. Main outcomes included volume of implant resorption and incidence of osteoconductivity at implant sites, imaging findings, adverse events, and the frequency of reoperations.

RESULTS

A total of 13 studies representing 668 patients with either knee or shoulder implants were included. Median follow-up was 28 months (range: 12-37 months). Biocomposite implants lost 88% of their original volume during follow-up. Osteoconductivity at the implant site was identified in 63% of cases. Adverse events included tunnel widening (3%), effusion (5%), and cyst formation (4%). Synovitis was not reported.

CONCLUSIONS

Biocomposite interference screws or suture anchors composed of PLGA/β-TCP almost fully absorb over 3 years while promoting osteoconductivity with few reported adverse events.

LEVEL OF EVIDENCE

Level IV, systematic review of Level I-IV studies.

In vivo erosion of orthopedic screws prepared from nacre (mother of pearl)

BACKGROUND

Biodegradable biomaterials have been proposed to prepare orthopedic devices. Nacre is a natural aragonitic material made of calcium carbonate and is bioerodible.

WORKING HYPOTHESIS

We postulated that nacre is biodegradable without provoking bone erosion and favors bone apposition.

MATERIAL AND METHODS

We prepared orthopedic screws from nacre of the giant oyster Pinctada maxima. Threaded screws (3.5mm diameter) were implanted in 6 ewes in the upper tibial metaphysis (3 to 4 screws per animal). Their trajectory was transcortical and intramedullary to the opposite cortex. Animals were kept for 3months (n=2) and 6 months (n=4). They did not develop local inflammation. Before euthanasia, they received a double calcein labeling. Bone samples were analyzed by X-ray nanotomography and histology after embedding in poly(methyl methacrylate). The fractal dimension of the screw profiles (measured by the box-counting method) was used to quantify surface erosion.

RESULTS

3D nanotomography showed a gradual erosion of the threads, which was confirmed by a decreased fractal dimension. Histologically, multinucleated cells (non-osteoclastic appearance) were visible at the surface of the screws. No ruffled border was seen in these cells but they had extensions creeping in the organic matter between the aragonite tablets. Bone apposition was noted in the transcortical path of the screws with limited osteoconduction at the endosteum. Mineralization rate was increased in these zones composed of woven bone in contact with the nacre.

DISCUSSION AND CONCLUSION

Screws prepared from nacre have the advantage of an in vivo resorbability by macrophage-derived cells and an osteoconductive apposition in contact with the material without triggering a local inflammatory reaction.

Management of complications after rotator cuff surgery

Rotator cuff repair (RCR) is a common procedure performed by orthopedic surgeons via arthroscopic, open, or mini-open techniques. While this surgery is considered to be of low morbidity, several potential complications can arise either intraoperatively or during the postoperative time period. Some of these complications are related to the surgical approach (arthroscopic or open), while others are patient dependent. Many of these complications can be managed through nonoperative means; however, early recognition and timely treatment is essential in limiting the long-term sequela and improving patient outcome. There are several different ways to classify complications after RCR repair: timing, severity, preventability, whether or not the pathology is intra- or extra-articular, and the type of treatment necessary. It is essential that the surgeon is cognizant of the etiology contributing to the failed RCR surgery in order to provide timely and proper management.