Utility of polymer cerclage cables in revision shoulder arthroplasty

No difference in clinical and radiological outcomes following fixation of transverse patella fractures with either suture tape or metallic cerclage: A retrospective comparative study

INTRODUCTION

Several surgical techniques have been proposed for the treatment of patellar fractures. The aim of this study is to compare the clinical efficacy and complication rates of treatment using suture tape circumferential cerclage (STCC) and metallic wire circumferential cerclage (MWCC) for the surgical treatment of displaced transverse patellar fractures (TPFs).

HYPOTHESIS

The hypothesis is that the use of the suture tape would be associated with a significantly lower rate of re-operation than metallic cerclage but no differences in other clinical outcomes.

PATIENTS AND METHODS

A retrospective comparative analysis of the clinical outcomes of consecutive patients undergoing fixation of TPFs with either MWCC or STCC between January 2017 and December 2018 was undertaken. All patients underwent evaluation with standardised radiographs at one, three, and six months after surgery to determine rates of union, non-union, loss of fixation and malunion. All patients underwent a final clinical evaluation at 18 months postoperatively to evaluate clinical scores and complications.

RESULTS

A total of 26 patients were included in the study. Thirteen patients underwent STCC and 13 underwent MWCC. There were no complications in the STCC group. In the MWCC group, one patient underwent hardware removal at 2 months postoperatively due to painful prominence. There was no significant difference in re-operation rates between the STCC and MWCC groups (p=1). There were no cases of non-union, malunion or loss of fixation throughout the series. At the final clinical follow-up of 18months, there were no significant differences in KSS, KOOS or Böstman scores between the groups.

CONCLUSION

No significant differences were identified when comparing the clinical outcomes of fixation of AO/OTA 34C1/2 fractures with suture tape or metallic cerclage fixation concerning re-operation rates, union rates, loss of fixation and functional outcome measures. These results cannot be extrapolated to more complex injury patterns or surgical techniques in which prominence of implanted material is more likely.

LEVEL OF EVIDENCE

III.

Cytotoxicity of 3D Printed Materials for Potential Dental Applications: An In Vitro Study

Aim of the Study:

This study aims to evaluate the cytotoxicity of different stereolithographic 3D printed materials and the polyetheretherketone for varying time intervals using MTT assay and by application of these materials for intra-oral usage.

Materials and Methods:

Three groups of disc specimens (5 mm diameter, 2 mm thick) were manufactured by either selective laser melting (PA6 nylon, fiber reinforced PA6 nylon) or milling (PEEK). The cytotoxicity of these materials was tested by culturing the samples on human fibroblast cell lines prior to MTT assays (3- (4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide, a yellow tetrazole). MTT assays were completed at 3, 6, and 10 days. Cell grown in normal medium without experimental material served as control. The total cell number and viability of cells pre-incubated with PA6 nylon, fiber-reinforced PA6 nylon, and PEEK were comparable to the control samples. Differences between the growth inhibitory effects of the samples in the MTT assay were below 0.05%.

Results:

Both nylon and fiber-reinforced nylon reduced the proliferation of normal human fibroblasts up to 6 days of treatment. PEEK had better biocompatibility than PA6 nylon and fiber-reinforced nylon. Both PA6 nylon and fiber-reinforced are 3DPrinted materials that showed cytotoxicity at 10 days. However, soaking the nylon materials for 6 days made them safe on normal human cells.

Conclusion:

PEEK material can be considered for intraoral usage as the material is biocompatible. Both PA6 nylon and fiber-reinforced PA6 nylon materials showed increased in-vitro cell death at 10 days, suggesting that they are non-biocompatible for intraoral usage beyond 6 days.

Is Nice knot suture comparable to wire for cerclage fixation? A biomechanical performance study

Background

Cerclage fixation is a known orthopedic technique shown to be beneficial for circumferential augmentation when screw fixation cannot be used or is undesirable. However, ongoing advances in suture materials and knot techniques exist, and there is a paucity of evidence existing which evaluates comparisons between the two. The objective of this study was to investigate the strength and durability of cerclage fixation between the Nice knot suture technique and monofilament wire.

Methods

Static displacement over time and compression load testing were analyzed. Compression testing was conducted with the Jamar Hydraulic Hand Dynamometer. Distraction testing was conducted using the Instron test system with its associated program. The Nice knot was tied using number 2 and number 5 FiberWire (Arthrex) and compared to monofilament wire. Clinical failure (displacement of 10 mm), absolute failure (opening of the knot or material failure), maximum compression achieved, and steady state compression maintained were the outcomes of interest.

Results

Double-stranded monofilament wire produces maximum consistent compression of 90 kg, followed by single-stranded monofilament wire (60 kg). Number 5 FiberWire has a higher maximum compression load than number 2 FiberWire (50 kg vs. 22 kg), but it is lower than that of the double-stranded monofilament wire constructs. When compared to the single-stranded monofilament construct, the number 5 FiberWire Nice knot is comparable (P < .05). Average steady state compression achieved after 10 minutes of resting showed double-stranded monofilament wire to be 65 kg compared to single- stranded monofilament wire at 42 kg, which when, compared to suture, number 5 FiberWire measured at 15 kg and number 2 FiberWire at 8 kg. Average tension results from Instron distraction testing showed the double-stranded monofilament wire construct was able to withstand greater forces up to a displacement of 6 mm, after which the number 5 FiberWire Nice knot was stiffer. Number 5 FiberWire shows the most linear tension relationship, revealing it more efficiently withstands elastic forces. Load to failure was higher in the number 5 FiberWire Nice knot construct than that in both the monofilament wire constructs. The modes of failure for the Nice knot were always at the knot suture interface rather than at the knot.

Conclusion

We propose this suture technique to be a viable alternative method for cerclaging to fix upper limb long-bone fractures.

Is suture cerclage fixation a valid treatment for intraoperative nondisplaced calcar fractures in reverse total shoulder arthroplasties?

Background

Implantation rates of reverse total shoulder arthroplasties continue to grow worldwide. Despite satisfying results, a distinct number of complications persist. Intraoperative fractures of the humeral shaft might occur in a certain number of cases. The literature is sparse regarding incidence and treatment options. This study analyzed the treatment using suture cerclage or stainless-steel-cable cerclage.

Methods

Our prospectively followed-up cohort of 860 patients who received primary reverse total shoulder arthroplasty in a tertiary referral hospital between September 2005 and August 2018 was screened for intraoperative medial humeral calcar fractures. The patients were retrospectively analyzed as per the treatment algorithm using (1) suture cerclage with FiberWire, (2) cable cerclage with stainless steel cable, or (3) no intervention. The outcome was radiologically and clinically (Subjective Shoulder Value and Constant score) evaluated.

Results

A total of 39 (4.5%) intraoperative calcar fractures of the humeral shaft were identified with 29 cases available for analysis at a mean follow-up time of 52 ± 27 months. Sixteen of them were treated with suture cerclage, 7 with metal cable cerclage, and 6 without intervention. All fractures were nondisplaced or could be reduced anatomically and healed without any stem subsidence or loosening within the first 4.5 months. The intervention groups reached similar values for the Subjective Shoulder Value (68%±27% vs. 79%±19%, suture vs. cable) and relative Constant score (65 % ± 25 % vs. 75 % ± 23).

Conclusion

Intraoperative medial calcar fractures can be sufficiently treated with metal or suture cerclage fixation. High-strength polyblend-polyethylene sutures seem to be a valid therapeutic option for selected medial calcar fractures of the humerus. In selected cases, however, benign neglect can result in excellent results as well.

A Tensionable Suture-based Cerclage Is an Alternative to Stainless Steel Cerclage Fixation for Stabilization of a Humeral Osteotomy During Shoulder Arthroplasty

INTRODUCTION

Fixation of periprosthetic humeral fractures is most commonly obtained with steel-based wires or cables; however, disadvantages with these constructs are numerous. Suture-based cerclages offer the advantage of easy handling, less radiographic interference, and risk of metallosis, as well as decreased risk of cutting into the soft humeral bone. Therefore, the purpose of this study was to compare a suture-based cerclage to a stainless steel wire cerclage (SSWC) for stabilization of the humerus during shoulder arthroplasty.

METHODS

In part I of the study, SSWC fixation was compared with single-looped tape cerclage and a double-looped tape cerclage (DLTC) fixation. In part II, a subsidence test was performed on 12 cadaveric humeri. After an osteotomy, the humeri were secured with either a SSWC or DLTC. Subsequently, a metal wedge was introduced into the humerus to simulate the stem of a shoulder arthroplasty.

RESULTS

In part I, load to 2-mm displacement was significantly higher for the DLTC construct compared with the SSWC construct (2,401 ± 483 N versus 750 ± 33 N; P < 0.0001). Load to failure was 935 ± 143 N with the SSWC, 1,737 ± 113 N with the single-looped tape cerclage, and 4,360 ± 463 N with the DLTC constructs, and all differences were statistically significant (P < 0.05). In part II, load at 20-mm subsidence was higher for the DLTC (320 ± 274 N) compared with the SSWC (247 ± 137 N), but no significant difference was observed (P > 0.05). However, gap displacement at 20 mm subsidence was significantly lower with the DLTC construct (0.33 ± 0.31 mm versus 0.77 ± 0.23 mm; P = 0.009). Load to failure was higher with the DLTC construct compared with the SSWC construct (4,447 ± 2,325 N versus 1,880 ± 1,089 N; P = 0.032), but the final gap displacement did not differ significantly (DLTC 5.23 ± 6.63 mm versus SSWC 6.03 ± 8.82 mm; P > 0.05).

DISCUSSION

A DLTC has higher load to failure and trends toward lower gap displacement compared with a SSWC. The DLTC construct may therefore be a viable alternative for fixation of periprosthetic fractures or osteotomies of the humeral shaft during shoulder arthroplasty.

Suture cerclage for stabilizing the humeral shaft during shoulder arthroplasty

Background

In shoulder arthroplasty, cerclage fixation techniques are used to stabilize osteotomies, fractures, and allografts. Fixation techniques including cerclage with metal and polymer cables have been described. The purpose of this study was to evaluate suture cerclage fixation of the humeral shaft during shoulder arthroplasty.

Materials and methods

Shoulder arthroplasty cases performed from 2012-2017 by 3 fellowship-trained shoulder arthroplasty surgeons were reviewed. Cases in which suture cerclage was used for osteotomy, fracture, or allograft fixation were identified. Demographic data, indications, implant types, fixation techniques, and complications were reviewed. Postoperative radiographs were analyzed for union, component loosening, and loss of fixation. American Shoulder and Elbow Surgeons and Single Assessment Numeric Evaluation scores were collected preoperatively and postoperatively.

Results

A total of 27 patients (3 primary and 24 revision cases) with a mean age of 69.6 years (range, 28-88 years) were available for follow-up at a mean of 12.6 months (range, 0.8-42.3 months) postoperatively. Humeral osteotomy alone was performed in 15 cases. Allograft alone was used in 1 case. Both allograft and osteotomy were used in 6 cases. Complications occurred in 3 patients (11%), comprising 1 postoperative periprosthetic fracture and 2 prosthetic joint infections; all required further surgery. Radiographs at final follow-up showed healing of all osteotomies and fractures. No hardware failure or implant loosening occurred. The mean postoperative American Shoulder and Elbow Surgeons and Single Assessment Numeric Evaluation scores were significantly improved (α = .05) compared with preoperative scores, from 21.4 to 44.5 (P = .002) and from 26.7 to 74.1 (P < .001), respectively.

Conclusion

Suture cerclage is safe and effective for humeral fixation in shoulder arthroplasty.

A review of metallic and non-metallic cerclage in orthopaedic surgery: Is there still a place for metallic cerclage?

Cerclage techniques are simple, yet effective techniques to treat certain fractures and are known as one of the first operative techniques in orthopaedic surgery. The days when a twisted metal wire was the only available cerclage technique nonetheless have passed and today there are many different materials and techniques available. This review evaluates the differences between metallic and non-metallic cerclage techniques, thereby looking at biomechanical, technical and biological aspects. It also provides an overview of clinical applications for non-metallic cerclages. The use of metallic versus non-metallic cerclage might differ depending on indication, location and involved tissues. Currently metallic cerclage is mostly used to repair fractures because of its believed higher absolute strength. More recently though, non-metallic cerclage has been proven to withstand the same loads, while having a lower complication rate. This review suggests that mainly in the upper limb a non-metallic cerclage technique might become the golden standard, while in the lower limb both metallic and non-metallic cerclage techniques are complementary and dependent on indication.

Intraoperative Periprosthetic Femur Fracture: A Biomechanical Analysis of Cerclage Fixation

Intraoperative periprosthetic femur fracture is a known complication of total hip arthroplasty (THA) and a variety of cerclage systems are available to manage these fractures. The purpose of this study was to examine the in situ biomechanical response of cerclage systems for fixation of periprosthetic femur fractures that occur during cementless THA. We compared cobalt chrome (CoCr) cables, synthetic cables, monofilament wires and hose clamps under axial compressive and torsional loading. Metallic constructs with a positive locking system performed the best, supporting the highest loads with minimal implant subsidence (both axial and angular) after loading. Overall, the CoCr cable and hose clamp had the highest construct stiffness and least reduction in stiffness with increased loading. They were not demonstrably different from each other.

Stainless steel wire versus FiberWire suture cerclage fixation to stabilize the humerus in total shoulder arthroplasty

HYPOTHESIS

No. 5 FiberWire (Arthrex, Naples, FL, USA) cerclage (FWC) and 1.25-mm stainless steel wire cerclage (SSWC) are biomechanically similar in resistance to prosthetic subsidence in shoulder arthroplasty.

METHODS

In this laboratory bench study, 3 different surgical knot configurations (4-throw knot, cow hitch, and simple hitch) using a No. 5 FWC were evaluated and compared with a 1.25-mm SSWC. First, distraction tests were performed using bovine femoral cortical half shells mounted on a testing jig. Cerclage tightening, load to a 3-mm gap opening, and load to total failure were measured. Second, uncemented humeral prosthetic stems were inserted into an experimentally split humeral medullary canal, secured by the cerclage. After 100 N of preloading, the prosthesis was advanced into the humerus at a speed of 0.2 mm/s, and resistance during subsidence up to a penetration depth of 10 mm, as well as gap opening, was measured.

RESULTS

Tightening force showed higher values for SSWC (618 N) than FWC (131-137 N) (P < .001). Load to total failure was comparable among the 3 different FWC knots (2,642-2,804 N), which were significantly stronger than SSWC (1,775 N, P < .001). At 3 mm of distraction, SSWC (1,820 N), cow hitch (1,803 N), and single-throw hitch (1,709 N) performed significantly better than a 4-throw knot (1,289 N) (P < .01). Subsidence testing showed no difference in force restraint or gap opening between the best FWC and SSWC.

CONCLUSIONS

FWCs appear, in vitro, equally suitable to steel wires to stabilize nondisplaced periprosthetic humeral fractures. To actively reduce a displaced fracture, steel wires may still be the first choice.