Fixation Strength of Polyetheretherketone Sheath-and-Bullet Device for Soft Tissue Repair in the Foot and Ankle

Polyetheretherketone development in bone tissue engineering and orthopedic surgery

Polyetheretherketone (PEEK) has been widely used in the medical field as an implant material, especially in bone tissue engineering and orthopedic surgery, in recent years. This material exhibits superior stability at high temperatures and is biosecured without harmful reactions. However, the chemical and biological inertness of PEEK still limits its applications. Recently, many approaches have been applied to improve its performance, including the modulation of physical morphology, chemical composition and antimicrobial agents, which advanced the osteointegration as well as antibacterial properties of PEEK materials. Based on the evolution of PEEK biomedical devices, many studies on the use of PEEK implants in spine surgery, joint surgery and trauma repair have been performed in the past few years, in most of which PEEK implants show better outcomes than traditional metal implants. This paper summarizes recent studies on the modification and application of biomedical PEEK materials, which provides further research directions for PEEK implants.

Global Compressive Loading from an Ultra-Thin PEEK Button Augment Enhances Fibrocartilage Regeneration of Rotator Cuff Enthesis

A PEEK button is developed to improve the tendon-to-bone compression area. In total, 18 goats were divided into 12-week, 4-week, and 0-week groups. All underwent bilateral detachment of the infraspinatus tendon. In the 12-week group, 6 were fixed with a 0.8-1 mm-thick PEEK augment (A-12, Augmented), and 6 were fixed with the double-row technique (DR-12). Overall, 6 infraspinatus were fixed with PEEK augment (A-4) and without PEEK augment (DR-4) in the 4-week group. The same condition was performed in the 0-week groups (A-0 and DR-0). Mechanical testing, immunohistochemistry assessment, cell responses, tissue alternation, surgical impact, remodeling, and the expression of type I, II, and III collagen of the native tendon-to-bone insertion and new footprint areas were evaluated. The average maximum load in the A-12 group (393.75 (84.40) N) was significantly larger than in the TOE-12 group (229.17 (43.94) N) (p < 0.001). Cell responses and tissue alternations in the 4-week group were slight. The new footprint area of the A-4 group had better fibrocartilage maturation and more type III collagen expression than in DR-4 group. This result proved the novel device is safe and provides superior load-displacement to the double-row technique. There is a trend toward better fibrocartilage maturation and more collagen III secretions in the PEEK augmentation group.

[Short-term safety and effectiveness of domestic polyether-ether-ketone suture anchors for rotator cuff repair: A multicenter, randomized, single-blind, parallel-controlled noninferiority study]

OBJECTIVE

A multicenter, randomized, single-blind, parallel-controlled noninferiority study was used to evaluate the short-term safety and effectiveness of domestic polyether-ether-ketone (PEEK) suture anchor for rotator cuff repair by comparing with the imported PEEK suture anchor commonly used in clinical practice.

METHODS

A total of 59 patients with rotator cuff tears who were admitted between May 2019 and October 2019 were selected as the research objects. Among them, 3 patients were excluded because they did not meet the selection criteria, and 1 patient withdrew from the study because of serious adverse events. A total of 55 patients were included in the study. They were randomly divided into trial group ( n=27) and control group ( n=28). The trial group used PEEK suture anchors produced from REJOIN Company, and the control group used PEEK suture anchors from American Arthrex Company. Two patients in control group were lost to follow-up. Twenty-seven patients in trial group and 26 patients in control group were included in the final quantitative analysis. There was no significant difference ( P>0.05) in gender, age, disease duration, side and sizes of rotator cuff tears, composition ratio of patients with type 2 diabetes, and preoperative American Shoulder and Elbow Surgeons (ASES) score, Constant-Murley score, University of California at Los Angeles (UCLA) score, and visual analogue scale (VAS) score. The patients were followed up regularly after operation. The postoperative follow-up included safety evaluation (complications, anchor position, and anchor bone reaction) and effectiveness evaluation (shoulder joint function and pain scores, rotator cuff integrity based on Sugaya classification criteria).

RESULTS

The operations in both groups were successfully completed, and there was no complication related to the operation and suture anchor. All incisions healed by first intention. There was no significant difference in follow-up time between trial group [(5.85±0.77) months] and control group [(5.96±0.72) months] ( t=0.535, P=0.595). MRI examination indicated that the repaired tendons were fixed and the anchors did not get loose or torn. At 1 day, 3 months, and 6 months after operation, there was no patient with grade 3-4 anchor bone reaction in the two groups, and there was no significant difference in the bone reaction grading between groups ( P>0.05). After operation, the VAS scores of the two groups gradually decreased, and the ASES scores, Constant-Murley scores, and UCLA scores gradually increased, and there were significant differences between groups at each time point ( P<0.05). There was no significant difference between groups at different time points ( P>0.05). There was no significant difference in Sugaya classification of rotator cuff integrity at 1 day, 3 months, and 6 months after operation between groups ( P>0.05).

CONCLUSION

The short-term safety and effectiveness of domestic PEEK suture anchors in rotator cuff tear repair are not significant different from those of imported PEEK suture anchors commonly used in clinical practice.

Smart scaffolds: shape memory polymers (SMPs) in tissue engineering

Smart scaffolds based on shape memory polymer (SMPs) have been increasingly studied in tissue engineering. The unique shape actuating ability of SMP scaffolds has been utilized to improve delivery and/or tissue defect filling. In this regard, these scaffolds may be self-deploying, self-expanding, or self-fitting. Smart scaffolds are generally thermoresponsive or hydroresponsive wherein shape recovery is driven by an increase in temperature or by hydration, respectively. Most smart scaffolds have been directed towards regenerating bone, cartilage, and cardiovascular tissues. A vast variety of smart scaffolds can be prepared with properties targeted for a specific tissue application. This breadth of smart scaffolds stems from the variety of compositions employed as well as the numerous methods used to fabricated scaffolds with the desired morphology. Smart scaffold compositions span across several distinct classes of SMPs, affording further tunability of properties using numerous approaches. Specifically, these SMPs include those based on physically cross-linked and chemically cross-linked networks and include widely studied shape memory polyurethanes (SMPUs). Various additives, ranging from nanoparticles to biologicals, have also been included to impart unique functionality to smart scaffolds. Thus, given their unique functionality and breadth of tunable properties, smart scaffolds have tremendous potential in tissue engineering.

A Comparison of Open-Construct PEEK Suture Anchor and Non-Vented Biocomposite Suture Anchor in Arthroscopic Rotator Cuff Repair: A Prospective Randomized Clinical Trial

PURPOSE

To compare radiologic bone ingrowth and the clinical outcomes of an open-construct (PEEK) (polyether ether ketone) suture anchor with those of a non-vented biocomposite suture anchor in patients with arthroscopic rotator cuff repair.

METHODS

Sixty-nine patients were randomly allocated into 2 groups based on type of suture anchors used for rotator cuff repair; group 1: open-construct PEEK anchor (36 patients), group 2: non-vented biocomposite anchor (33 patients). The status of bone ingrowth into the anchor and the presence of cyst formation were evaluated at 6 months postoperatively by computed tomography scan using the Modified Barber's ossification scale. The American Shoulder and Elbow Surgeons score, Constant score, and visual analog scale score for pain and range of motion were evaluated. Magnetic resonance imaging or ultrasonography was performed at 12 months postoperatively to examine the integrity of the repaired rotator cuff tendon.

RESULTS

Significant improvements in shoulder function and pain relief were observed regardless of the anchor used (both Group 1 and 2; P < .001). No differences were found in functional scores and range of motion between the 2 groups. Group 1 showed better bone ingrowth grades than group 2 (poor 2.8 vs 24.2%, fair 27.8 vs 39.4%, good 38.9 vs 33.3%, and excellent 30.6 vs 3.0%; P < .001). The rate of cyst formation around the anchor on the 6 months' postoperative computed tomography (group 1: 14% and group 2: 12%) and re-tear rate at 12 months (5% each) showed no difference between the 2 groups.

CONCLUSIONS

Shoulder function was improved after complete rotator cuff repair and similar clinical outcomes were achieved regardless of suture anchor material and shape. However, the open-construct PEEK anchor provided better bone ingrowth into the anchor than the non-vented biocomposite anchor at 6 months after arthroscopic rotator cuff repair.

LEVEL OF EVIDENCE

Level I; Prospective Randomized Trial.

Axial and shear pullout forces of composite, porcine and human metatarsal and cuboid bones

Objectives

The varying mechanical properties of human bone have influence on the study results. Pullout and shear forces of human bone were compared to different substitutes to evaluate their suitability for biomechanical studies.

Methods

After bone mineral density (BMD) determination, axial pullout tests were performed with cortical 3.5 mm nonlocking (NL) and 2.7 mm head locking (HL) screws on human, porcine and polyurethane composite bones. Porcine and human constructs were additionally loaded in shear direction.

Results

Apparent BMD was significantly lower in osteoporotic (159 mgHA/ccm ± 56) and nonosteoporotic (229 mgHA/ccm ± 25) human bone than that in porcine bone (325 mgHA/ccm ± 42; p < 0.01). Axial construct stiffness and ultimate pullout force of porcine bone (NL: 666N/mm ± 226, 910N ± 140; HL: 309N/mm ± 88, 744N ± 185) was significantly different from composite bone (NL: 1284N/mm ± 161; 1175N ± 116; HL: 1241N/mm ± 172, 1185N ± 225) and osteoporotic human bone (NL: 204N/mm ± 121, 185N ± 113; HL: 201N/mm ± 65; 189N ± 58) but not from nonosteoporotic human bone (NL: 620N/mm ± 205, 852N ± 281; HL: 399N/mm ± 224; 567N ± 242). Porcine bone exhibited an ultimate shear force (NL: 278N ± 99; HL: 431N ± 155) comparable to nonosteoporotic human bone (NL: 207 ± 68: HL: 374N ± 137).

Conclusion

Screw pullout and shear forces of porcine bone are close to nonosteoporotic human bone.

The translational potential of this article

Human bone specimens used in biomechanical studies are predominantly of osteoporotic bone quality. Conclusions on nonosteoporotic human bone behaviour are difficult. Alternatives such as porcine bone and composite bone were investigated, and it could be shown that screw pullout and screw shear forces of porcine bone are close to nonosteoporotic human bone.