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

SARS-Cov-2 related shoulder pain and stiffness associated to humeral osteolysis after arthroscopic rotator cuff repair: A case report

INTRODUCTION AND IMPORTANCE

Complications using bioresorbable anchors in arthroscopic rotator cuff surgery include osteolysis, aseptic synovitis, and foreign body reaction. However, the precise triggering factors are unknown.

CASE PRESENTATION

A healthy, 63-year-old male patient underwent rotator cuff repair using 7PLGA/b-TCP anchors. Nine months after surgery he returned to the senior author because of right shoulder pain and stiffness, pain in the right hand, foot and leg, and presence of erythematous patches at the aforementioned joints following SARS-Cov-2 infection, as well as increasing in blood inflammatory markers. Magnetic Resonance Arthrography (Arthro-MRI) showed no rotator cuff tendons re-tear but intra-articular synovitis, subacromial bursitis and humeral osteitis. A diagnostic arthroscopy, intra-articular fluid collection, biopsy and joint lavage was performed to rule out a septic arthritis. Co-amoxicillin 2.2 g intravenous treatment was administered following samples. Histological analysis of synovial tissue showed fibrin-exudative synovitis, while humeral bone biopsy showed an anchor resorption reaction. All microbiological analysis showed sterile samples. Three months post-lavage follow-up physical examination showed painless, recovered mobility, while Arthro-MRI showed a significant post-refixation remodeling of the rotator cuff tendons and reduction in humeral head osteitis and synovitis.

CLINICAL DISCUSSION

The abrupt onset of symptomatology and the close chronological link with SARS-Cov-2 infection suggests a causal relationship between clinical and radiological manifestations and the infection itself, with clinical and radiological manifestation being a viral host response reaction to SARS-Cov-2 infection.

CONCLUSION

Shoulder pain, stiffness and humeral osteitis could be manifestations of a viral host response to SARS-Cov-2 infection.

Management of Bone Loss and Tunnel Widening in Revision ACL Reconstruction

➤ Both mechanical and biological factors can contribute to bone loss and tunnel widening following primary anterior cruciate ligament (ACL) reconstruction.➤ Revision ACL surgery success is dependent on graft position, fixation, and biological incorporation.➤ Both 1-stage and 2-stage revision ACL reconstructions can be successful in correctly indicated patients.➤ Potential future solutions may involve the incorporation of biological agents to enhance revision ACL surgery, including the use of bone marrow aspirate concentrate, platelet-rich plasma, and bone morphogenetic protein-2.

Continuously released Zn2+ in 3D-printed PLGA/β-TCP/Zn scaffolds for bone defect repair by improving osteoinductive and anti-inflammatory properties

Long-term nonunion of bone defects has always been a major problem in orthopedic treatment. Artificial bone graft materials such as Poly (lactic-co-glycolic acid)/β-tricalcium phosphate (PLGA/β-TCP) scaffolds are expected to solve this problem due to their suitable degradation rate and good osteoconductivity. However, insufficient mechanical properties, lack of osteoinductivity and infections after implanted limit its large-scale clinical application. Hence, we proposed a novel bone repair bioscaffold by adding zinc submicron particles to PLGA/β-TCP using low temperature rapid prototyping 3D printing technology. We first screened the scaffolds with 1 wt% Zn that had good biocompatibility and could stably release a safe dose of zinc ions within 16 weeks to ensure long-term non-toxicity. As designed, the scaffold had a multi-level porous structure of biomimetic cancellous bone, and the Young's modulus (63.41 ± 1.89 MPa) and compressive strength (2.887 ± 0.025 MPa) of the scaffold were close to those of cancellous bone. In addition, after a series of in vitro and in vivo experiments, the scaffolds proved to have no adverse effects on the viability of BMSCs and promoted their adhesion and osteogenic differentiation, as well as exhibiting higher osteogenic and anti-inflammatory properties than PLGA/β-TCP scaffold without zinc particles. We also found that this osteogenic and anti-inflammatory effect might be related to Wnt/β-catenin, P38 MAPK and NFkB pathways. This study lay a foundation for the follow-up study of bone regeneration mechanism of Zn-containing biomaterials. We envision that this scaffold may become a new strategy for clinical treatment of bone defects.

Evaluation of the degradation of two bioabsorbable interference screws: an in-vivo study in sheep

PURPOSE

To evaluate in-vivo degradation of two bioabsorbable interference screws.

METHODS

Twenty-two crossbred Santa Inês ewes were used. A poly-DL-lactide (PDLLA) screw (70%/30%) was inserted in the right pelvic limb, and a PDLLA screw (70%) + β-tri-calcium phosphate (β-TCP) (30%) in the left pelvic limb. Animals were euthanized at one, four, seven and a half and 18 months after surgery. Plain radiography, computed tomography (CT), microCT, and histological analysis were accomplished.

RESULTS

PDLLA screw was hypodense at all evaluation moments, but with progressive density increase along the central axis, whereas PDLLA/β-TCP was initially hyperdense and progressively lost this characteristic. No adverse reactions were observed on histological evaluation.

CONCLUSIONS

The inclusion of β-TCP favors screw degradation since the PDLLA/β-TCP screws evidenced a more intense degradation process than the PDLLA screws at the last evaluation. PDLLA screws showed higher bone production, evident around the screw thread, inside the lateral perforations, and in the central canal, whereas the PDLLA/β-TCP screws presented less bone tissue at the implantation site.

Patellar Stress Fracture After Suture Anchor Patellar Tendon Repair in an Active Duty Military Member: A Case Report

CASE

A 31-year-old US service member presented with a patellar tendon tear that was repaired acutely with 2 biocomposite suture anchors. He presented more than 2 years later with a stress fracture through a suture anchor drill hole and was treated with partially threaded screw fixation.

CONCLUSION

Stress fracture through a suture anchor drill hole after patellar tendon repair is a previously unreported complication. Surgeons should have a high index of suspicion and low threshold to obtain advanced imaging in cases of unexplained pain after patellar tendon repair.

Quantitative assessment of increase in orbital volume after orbital floor fracture reconstruction using a bioabsorbable implant

PURPOSE

To assess the postoperative changes in the orbital volume and the degree of enophthalmos after orbital floor fracture reconstruction using a bioabsorbable implant and to determine the predictors of postoperative orbital volume change.

METHODS

Single-center, retrospective case series of 16 patients who underwent orbital floor fracture reconstruction using a bioabsorbable implant [poly(L-lactic acid)-poly(glycolic acid)/β-tricalcium phosphate; Biobsorb β^®] were included. Three-dimensional volumetric calculations of orbit were determined using computed tomography scans and the degree of enophthalmos was assessed via Hertel exophthalmometry. Postoperative changes in the orbital volume and the degree of enophthalmos and their correlation were assessed.

RESULTS

The mean volume of fractured orbits immediately after surgery was 22.26 ± 1.98 cm³, increasing to 23.67 ± 2.00 cm³ at 6-month follow-up (p < 0.001); the increased orbital volume was associated with postoperative deformation of the implant. The mean degree of enophthalmos was 0.09 ± 0.27 mm at 1-month follow-up, which increased to 0.66 ± 0.30 mm at 6-month follow-up (p = 0.001). Increase in orbital volume and enophthalmos progression showed a linear correlation (R = 0.682, p = 0.004). Patients with more herniated orbital tissue preoperatively showed increased postoperative orbital volume change (p = 0.015), whereas the size of the fracture area was not predictive of postoperative orbital volume change (p = 0.442).

CONCLUSION

Increase in orbital volume by deformation of the bioabsorbable implant resulted in progressive enophthalmos during the postoperative follow-up period after orbital floor fracture reconstruction. Thus, careful selection of proper implants before surgery and close postoperative follow-up is needed for an optimal outcome.

Periimplant osteolysis does not affect the outcome of rotator cuff repair: a systematic review and meta-analysis

PURPOSE

The goal of this study was to perform a systematic review and meta-analysis to compare the clinical and radiologic outcomes of rotator cuff repair, depending on the presence of developed periimplant osteolysis (PIO) after using suture anchors.

METHODS

The electronic databases of MEDLINE, EMBASE, and the Cochrane Central Register of Controlled Trials were searched for articles published up until October 2019 to find relevant articles comparing the outcomes of rotator cuff repair between the periimplant osteolysis group and non-periimplant osteolysis group. Data searching, extraction, analysis, and quality assessment were performed according to the Cochrane Collaboration guidelines. The results are presented as risk ratio (RR) for binary outcomes and standardised mean difference (SMD) for continuous outcomes with 95% confidence intervals (CI).

RESULTS

Six clinical studies were included. No significant differences were found between the group with periimplant osteolysis and the group without periimplant osteolysis regarding retear rate (RR = 1.34; 95% CI 0.93-1.94; I² = 28%), postoperative clinical scores (SMD = 0.29; 95% CI - 0.26 to 0.83; I² = 80%) and range of motion (ROM); forward flexion (SMD = 0.39; 95% CI - 0.16 to 0.93; I² = 0%), external rotation (SMD = - 0.10; 95% CI - 0.64 to 0.45; I² = 0%) and internal rotation (SMD = - 0.37; 95% CI - 0.92 to 0.17; I² = 0%).

CONCLUSION

The presence of periimplant osteolysis after rotator cuff repair with suture anchor does not affect the clinical outcomes such as retear rate, clinical scoring, and ROM. However, as there was no standard consensus on the criteria for evaluating periimplant osteolysis, this result may not fully reflect the effect of periimplant osteolysis depending on its severity.

LEVEL OF EVIDENCE

Level IV.

Stacked Biocomposite Screws in a Single-Stage Revision Anterior Cruciate Ligament Reconstruction Has Acceptable Fixation Strength in a Porcine Cadaveric Model

BACKGROUND

Stacked screws is a commonly used technique in single-stage revision anterior cruciate ligament (ACL) reconstruction in the setting of bone loss, but there are limited data to support its use.

HYPOTHESIS

Two configurations of a biocomposite stacked screws construct have similar fixation strength and linear stiffness as a primary ACL reconstruction construct in a biomechanical model.

STUDY DESIGN

Controlled laboratory study.

METHODS

A total of 30 porcine legs were divided into 3 groups. Group 1 underwent primary ACL reconstruction with a patellar tendon graft fixed into the femur, with an 8-mm biocomposite interference screw of beta-tricalcium phosphate and poly lactide-co-glycolide. For a revision ACL reconstruction model, groups 2 and 3 had bone tunnels created and subsequently filled with 12-mm biocomposite screws. New bone tunnels were drilled through the filler screw and the surrounding bone, and the patellar bone plug was inserted. Group 2 was fixed with 8-mm biocomposite screws on the side of the graft opposite the filler screw, while group 3 had the interference screw interposed between the graft and the filler screw. The construct was loaded at 1.5 mm/s in line with the tunnel until failure. Load to failure, linear stiffness, and mode of failure were recorded.

RESULTS

The mean pullout strength for groups 1, 2, and 3 was 626 ± 145 N, 653 ± 152 N, and 720 ± 125 N, respectively (P = .328). The mean linear stiffness of the construct in groups 1, 2, and 3 was 71.4 ± 9.9 N/mm, 84.1 ± 11.1 N/mm, and 82.0 ± 10.8 N/mm, respectively. Group 2 was significantly stiffer than group 1 (P = .037).

CONCLUSION

Two configurations of a biocomposite stacked screws construct for a single-stage revision ACL reconstruction in the setting of bone loss show a similar fixation strength and linear stiffness to a primary ACL reconstruction at time zero in a porcine model.

CLINICAL RELEVANCE

In the setting of bone loss from tunnel malpositioning, a single-stage revision ACL reconstruction using a stacked screws construct may provide adequate fixation strength and linear stiffness.

Porous Electroactive and Biodegradable Polyurethane Membrane through Self-Doping Organogel

In order to improve the processability of conductive polyurethane (CPU) containing aniline oligomers, a new CPU containing aniline trimer (AT) and l-lysine (PUAT) are designed and synthesized. Further, the 3D porous PUAT membranes have been prepared by a simple gel cooperated with freeze-drying method. Chemical testings and conductive properties testify a self- doping model of PUAT based on the rich electronic l-lysine and electroaffinity AT moities. The self-doping behavior further endows the PUAT copolymers specific characteristics such as high electrical conductivity and the formation of the polaron lattice like-structure in good solvent dimethyl sulfoxide. The combination of organogel and freeze-drying could prevent the collapse of pore structure when the copolymers are molded as membranes. The synergistic effect of l-lysine and AT components has a strong influence on the dissolution, degradation, thermal stability, and mechanical properties of PUAT. The excellent properties of PUAT would broad the application of conductive polymers in biomedicine field.

Comparison between all-suture and biocomposite anchors in the arthroscopic treatment of traumatic anterior shoulder instability: A retrospective cohort study

Purpose

Suture anchors have revolutionized arthroscopic surgery, enabling direct soft tissue-to-bone repair. There are many types of anchors still used in arthroscopic shoulder operations. We sought to compare the clinical outcome of all-suture and biocomposite anchors when used in arthroscopic Bankart repair for patients suffering from anterior shoulder instability.

Methods

A single-center retrospective cohort study of 30 patients (mean age: 26.6 years, SD: 8.8 years, male/female ratio: 5/1, mean follow up: 28 months, SD: 23.8, range: 12-92) with anterior shoulder instability was conducted. Patients were divided into 2 groups based upon the type of suture anchors used for the Bankart repair: group A (14 patients) used only all-suture anchors and group B (16 patients) used only biocomposite anchors. Outcomes reported were postoperative dislocations, positive shoulder apprehension test, self-reported sense of shoulder instability, return to activities of daily living, return to sports, patient satisfaction and complications. Patient reported outcome measures (PROMs) used were the Rowe Score for Instability, Constant Shoulder Score, Walch Duplay Score, The American Shoulder and Elbow Surgeons (ASES) Shoulder Score, Oxford Shoulder Instability Score and external rotation at 90° of arm abduction, external rotation at 0° of arm abduction, forward flexion, abduction, adduction and internal rotation.

Results

Rates of postoperative shoulder dislocation demonstrated no significant difference between the 2 groups (p > .05). Four postoperative dislocations happened, two in each group (14.3% and 12.5% for all suture only and biocomposite only groups, respectively), with three of them being traumatic. In addition, no significant differences were observed amongst groups regarding shoulder apprehension test (group A: 85.7% vs. group B: 93.8%), sense of shoulder instability (7.1% vs. 6.3%), return to activities of daily living (group A: 85.7% vs. group B: 93.8%), return to sports (group A: 85.7% vs. group B: 87.5%), patient satisfaction (moderate level: group A 21.4% vs. group B 12.5%), and PROMs.

Conclusion

The short-term failure rate and clinical/functional outcomes of arthroscopic Bankart repair using all-suture anchors is similar to the use of biocompatible anchors.

Level of evidence

Level III, retrospective cohort study.

Clinical and Radiologic Outcomes of Combined Use of Biocomposite and PEEK Suture Anchors during Arthroscopic Rotator Cuff Repair: A Prospective Observational Study

The aim of the current study was to evaluate the functional and radiologic outcomes of biocompatible non-absorbable PEEK (polyetheretherketone) and biocomposite (poly-L-lactic acid/poly(lactic-co-glycolic acid) 70% + β-tricalcium phosphate) anchors, especially in terms of perianchor cyst formation during the first six months postoperatively. We prospectively analysed 29 patients who underwent arthroscopic rotator cuff repair between March and May 2019. Both PEEK and biocomposite suture anchors were used as lateral anchors in one body. Clinical outcomes were assessed using the shoulder range of motion (ROM), visual analogue scale (VAS) for pain and satisfactory score, American Shoulder and Elbow Surgeons (ASES) score, and Simple Shoulder Test (SST). All these were obtained in patients preoperatively at 3 and 6 months after surgery. The imaging evaluation included perianchor cyst formation, anchor absorption, repaired cuff integrity, and retear pattern. All functional outcomes significantly improved over time. The biocomposite anchor had a statistically significant tendency to form higher grades of fluid collection at 3 months after surgery. However, the perianchor cyst reduced by the sixth postoperative month. Six months postoperatively, the functional outcomes were improved after rotator cuff repair and similar degrees of perianchor cyst formation were observed, regardless of the suture anchor material used.

Biocomposite Interference Screws in Anterior Cruciate Ligament Reconstruction: Osteoconductivity and Degradation

Purpose

To evaluate the long-term in vivo degradation of an amorphous stereoisomer combined with micro β-tricalcium phosphate poly levo (96%)/dextro (4%) lactide beta-tricalcium phosphate biocomposite interference screw.

Methods

A study approved by the institutional review board of in vivo biologic behavior of the screw was initiated in 2011 using an anterior cruciate ligament (ACL) reconstruction model. Twenty patients undergoing bone–patellar tendon–bone ACL reconstruction fixed at the femur and tibia with these biocomposite screws followed at least 36 months were evaluated by physical, radiographic, and computed tomography (CT) evaluations. Lysholm, Tegner, Cincinnati, and International Knee Documentation Committee scores were obtained. CT Hounsfield unit (HU) data were obtained at the femoral and tibial screw and other bone sites. An ossification quality score (range 1-4) was used to determine osteoconductivity at the screw sites.

Results

In total, 11 male and 9 female patients evaluated by CT scan and radiographs a mean of 41 months postsurgery (range, 37-51) showed bone plug healing to the tunnel wall and the screw replaced with calcified and nontrabecular material. Osteoconductivity was present in 34 of 40 tunnels (85%) and nearly complete or complete (type 3 or 4 ossification) in 10 of 40 (25%). Mean screw-site densities (femoral 239 HU; tibial 290 HU) were consistent with cancellous bone density. One positive pivot-shift test was found. Lysholm, Cincinnati, Tegner, and International Knee Documentation Committee activity scores improved from 46.9, 43.5, 1.9, and 1.7 preoperatively to 92, 90.2, 6.0, and 3.2 at follow-up, respectively. The average postoperative Single Assessment Numeric Evaluation score was 86 and mean KT-1000 arthrometer difference was 0.32 mm.

Conclusions

The micro β-tricalcium phosphate poly levo (96%)/dextro (4%) lactide beta-tricalcium phosphate interference screw was replaced by calcified, nontrabecular material a mean of 42 months after implantation in a bone–patellar tendon–bone ACL reconstruction model. Osteoconductivity was confirmed.

Level of Evidence

Level IV (therapeutic case series).

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.

Three anchor concepts for rotator cuff repair in standardized physiological and osteoporotic bone: a biomechanical study

BACKGROUND

Previous biomechanical studies used single-pull destructive tests in line with the anchor and are limited by a great variability of bone density of cadaver samples. To overcome these limitations, a more physiological test setting was provided using titanium, bioresorbable, and all-suture anchors.

METHODS

In this controlled laboratory study, 3 anchor constructs were divided into 2 groups: physiological and osteoporotic. Sixty standardized artificial bone specimens (=10 for each anchor in each group) were used for biomechanical testing. The anchors were inserted at a 45° angle as during surgery. Cyclic loading for 1000 cycles followed by ultimate load-to-failure (ULTF) testing was performed. Elongation, ultimate load at failure, and the mode of failure were noted.

RESULTS

In the physiological group, the ULTF for the all-suture anchor (mean [standard deviation], 632.9 [96.8 N]) was found to be significantly higher than for the other anchors (titanium, 497.1 [50.5] N, and bioresorbable, 322.4 [3.1 N], P < .0001). The titanium anchor showed a significantly higher ULTF than the bioresorbable anchor (P < .0001). In the osteoporotic group, the all-suture anchor again showed a higher ULTF compared to the bioresorbable anchor (500.9 [50.6] N vs. 315.1 [11.3] N, P < .0001). In the osteoporotic group, cyclic loading revealed a higher elongation after 1000 loading cycles for the bioresorbable (0.40 [0.12] mm) compared to the titanium (0.22 [0.11] mm; P = .01) as well as the all-suture anchor (0.19 [0.15] mm, P = .003).

CONCLUSION

Regarding ULTF, the all-suture anchor outperformed the other anchors in physiological bone, but in osteoporotic bone, significance was reached only compared to the bioresorbable anchor. Although cyclic loading revealed significant differences, these might not be clinically relevant.

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.

Biocomposite Suture Anchors Remain Visible Two Years After Rotator Cuff Repair

BACKGROUND

Biocomposite suture anchors containing osteoconductive materials have gained popularity in rotator cuff repairs. However, little is known about the influence of the addition of osteoconductive materials on implant resorption, bone reaction, tendon healing, and clinical outcomes scores.

QUESTIONS/PURPOSES

(1) What percentage of suture anchors were not completely resorbed 2 years after implantation? (2) What are the diameters of the bone bed in relation to the implant? (3) Is tendon integrity correlated with bone tunnel diameter? (4) Is there an association between tunnel widening, periimplant fluid film grade, biodegradation grade, and retear with clinical outcomes scores, such as the Western Ontario Rotator Cuff Index (WORC) and the Oxford Shoulder Score (OSS)?

METHODS

Thirty-six patients were enrolled from August 2012 to January 2014. The following inclusion criteria were applied: (1) reparable full-thickness supraspinatus tendon tears, (2) double-row suture bridge techniques applied for supraspinatus repair, (3) use of biocomposites suture anchor implants composed of poly L-lactic acid (PLLA) and β-tricalcium phosphate (TCP) exclusively, and (4) a minimum of 2 years followup. Four patients met the exclusion criteria, and seven of 36 patients (19%) were lost to followup. Thereby, 25 patients (84 implants) were included in this retrospective study. To answer the study's questions, the following methods were applied: (1) The resorption of the implants and periimplant fluid film were assessed on MRI using a four-stage scale system, (2) bone bed diameter was measured on MRI at three different points on the longitudinal central axis of each anchor, (3) tendon integrity was evaluated on MRI according to the Sugaya classification and correlated to bone tunnel diameter, and (4) assessed tunnel diameters, periimplant fluid film grade, biodegradation grade, and tendon condition were related to clinical outcomes scores at the time of followup (2.3 ± 0.3 years). The intraobserver reliability was 0.981 (p < 0.001) and interobserver reliability was 0.895 (p < 0.001).

RESULTS

At 2.3 ± 0.3 years, most analyzed suture anchors (76 of 84 [90%]) were, with varying degrees of degradation, still visible. Bone tunnels showed minor widening (0.4 ± 1.4 mm) at the base, but osseous ingrowth was detected as narrowing at the middle (0.1 ± 1.1 mm) and at the apex (1.4 ± 1.7 mm) of the implants. Patients with retears (Sugaya Grades 4-5) had narrower tunnels (3.6 ± 1.8 mm) than patients without retears (Sugaya Grades 1-3; 4.4 ± 1.6 mm; mean difference, 0.782 [95% confidence interval {CI}: 0.009-1.6]; p = 0.050). WORC and Oxford scores were not associated with the tunnel widening amount, fluid film grade, biodegradation grade, or tendon retear.

CONCLUSIONS

In light of the results of the present study, surgeons should consider in their daily practice that the resorption process of these implants may be slower than assumed so far, but no association with severe implant-related complications has been found in the short term. Future studies should focus on the evaluation of the effects of osteoconductive materials on resorption, tendon healing, and clinical outcomes in the long term and on the integration process in different rotator cuff reconstruction techniques.

LEVEL OF EVIDENCE

Level IV, therapeutic study.

Osteoconductive resorption characteristics of a novel biocomposite suture anchor material in rotator cuff repair

BACKGROUND

Bioabsorbable suture anchors have been associated with bone-derived complications, such as osteolysis and cyst formation, after rotator cuff repair. The purpose of this study was to assess the osseous degradation process of the novel biocomposite suture anchor material polylactic-co-glycolic acid (PLGA)/beta-tricalcium phosphate (ß-TCP)/calcium sulfate (CS) after arthroscopic single-row rotator cuff repair. The focus of interest was the appearance of osteolysis and the rate of total resorption of the implants after 21 months.

METHODS

Forty-eight patients with 82 implanted suture anchors who had undergone arthroscopic rotator cuff repair between January 2015 and March 2016 at our institution were retrospectively evaluated by postoperative magnetic resonance imaging. The appearance of osteolysis was classified by measurement of the peri-implant fluid. The degree of resorption was measured by grading the persistent visibility of the anchor structures. The integrity of the rotator cuff tendon was analyzed to discover possible retear or anchor pull-out complications.

RESULTS

After a follow-up of 21.2 (± 5.4) months, osteolysis was detected in only two anchors (2.4%), and none of these defects exceeded the diameter of the former suture anchor (5.5 mm). Fifty percent of the anchors were fully degraded and no longer visible. Furthermore, only two retears of the rotator cuff occurred, and no anchor pull-out complications were detected.

CONCLUSION

PGLA/β-TCP/CS is a fully resorbable and osteoconductive suture anchor material that seems to have superior resorption characteristics compared to those of other bioabsorbable suture anchor materials commonly used in arthroscopic rotator cuff repair.

TRIAL REGISTRATION

The presented study was retrospectively registered by the commission for ethics at the Ärztekammer Nordrhein with the registration number 2016433 on January 17, 2017. All participating patients gave written consent for participation and the publication of their data.

LEVEL OF EVIDENCE

IV.

Intramedullary nailing of forearm shaft fractures by biodegradable compared with titanium nails: Results of a prospective randomized trial in children with at least two years of follow-up

There are disadvantages in Elastic Stable Intramedullary Nailing (ESIN) of forearm-shaft fractures, such as the need of implant removal. Biodegradable Intramedullary Nailing (BIN) is a new technique developed for these fractures. We hypothesized that there is no difference in rotational ROM between the patients treated by BIN vs. ESIN. A randomized, controlled clinical trial included patients, aged 5-15 years, requiring surgery for forearm-shaft fractures. Biodegradable polylactide-co-glycolide (PLGA) nails (Activa IM-Nail™, Bioretec Ltd., Finland) were used in 19 and titanium nails (TEN^®, SynthesDePuy Ltd., USA) in 16 patients. Rotational ROM of forearm after two years was the primary outcome. Elbow and wrist ROM, pain and radiographic bone healing were secondary outcomes. Forearm rotation was mean 162° and 151° in BIN and ESIN groups, respectively (P = 0.201). No difference between the groups was found in any other ROMs. Three cases in the ESIN vs. none in the BIN group reported pain (P = 0.113). There was no clinically significant residual angulation in radiographs. Two adolescents in the BIN group vs. none in the ESIN (P = 0.245) were excluded because of implant failure; another two with complete bone union suffered from re-injury. Therefore, satisfactory implant stability among older children needs to be studied.

Formulation and in vitro characterization of rifampicin-loaded porous poly (ε-caprolactone) microspheres for sustained skeletal delivery

PURPOSE

Mycobacterium tuberculosis is a serious public health problem affecting hundreds of millions of elderly people worldwide, which is difficult to be treated by traditional methods because of the peculiarity of skeletal system and liver damage caused by high-dose administration. In this research, a porous drug release system has been attempted to encapsulate rifampicin (RIF) into poly (ε-caprolactone) (PCL) microspheres to improve the efficacy and benefit of anti-tuberculosis drug in skeletal system.

MATERIALS AND METHODS

The microspheres prepared by two different methods, oil-in-oil (o/o) emulsion solvent evaporation method and oil-in-water (o/w) method, were characterized in terms of morphology, size, encapsulation efficiency, drug distribution, degradation, and crystallinity.

RESULTS

The microspheres exhibited a porous structure with evenly drug distribution prepared by o/o emulsion solvent evaporation method, and their diameter ranged from 50.54 to 57.34 μm. The encapsulation efficiency was up to 61.86% when drug-loading content was only 1.51%, and showed a little decrease with the drug-loading content increasing. In vitro release studies revealed that the drug release from porous microspheres was controlled by non-Fickian diffusion, and almost 80% of the RIF were completely released after 10 days. The results of RIF-loaded microspheres on the antibacterial activity against Staphylococcus aureus proved that the porous microspheres had strong antibacterial ability. In addition, the polymer crystallinity had prominent influence on the degradation rate of microspheres regardless of the morphology.

CONCLUSION

It was an efficient way to entrap slightly water-soluble drug like RIF into PCL by o/o emulsion solvent evaporation method with uniform drug distribution. The RIF-loaded porous PCL microspheres showed the combination of good antimicrobial properties and excellent cytocompatibility, and it could generate gentle environment by PCL slow degradation.

Clinical Outcomes of Arthroscopic Rotator Cuff Repair Using Poly Lactic-co-glycolic Acid Plus β-tricalcium Phosphate Biocomposite Suture Anchors

Background

This study is performed to evaluate anchor-related outcomes and complications after arthroscopic rotator cuff repair using 30% β-tricalcium phosphate (β-TCP) with 70% poly lactic-co-glycolic acid (PLGA) biocomposite suture anchors.

Methods

A total of 78 patients (mean age, 61.3 ± 6.9 years) who underwent arthroscopic medium-to-large full-thickness rotator cuff tear repair were enrolled. The technique employed 30% β-TCP with 70% PLGA biocomposite suture anchors at the medial row (38 patients, Healix BR^TM anchor [Healix group]; 40 patients, Fixone anchor B [Fixone group]). The radiologic outcomes (including perianchor cyst formation or bone substitution) and anatomical outcomes of the healing failure rate were evaluated using magnetic resonance imaging at least 6 months after surgery, the pain visual analogue scale at 3, 6 months, and final follow-up visit, and American Shoulder and Elbow Surgeons scores at least 1 year postoperatively. Anchor-related complications were also evaluated.

Results

The perianchor cyst formation incidence was similar for both groups (60.5%, Healix group; 60.0%, Fixone group; p=0.967), although severe perianchor cyst incidence was slightly lower in the Fixone group (15.0%) than in the Healix group (21.1%). There was no occurrence of anchor absorption and bone substitution. No differences were observed in the healing failure rate (13.2%, Healix group; 15.0%, Fixone group; p=0.815) and functional outcome between groups (all p>0.05). Anchor breakage occurred in 5 patients (2 Healix anchors and 3 Fixone anchors); however, there were no major anchor-related complications in either group.

Conclusions

No differences were observed in the clinical outcomes of the Healix and Fixone groups, neither were there any accompanying major anchor-related complications.