Median Sternotomy Closure in Dogs: A Mechanical Comparison of Technique Stability

Biomechanical comparison of bone staple fixation methods with suture material for median sternotomy closure using 3D-printed bone models

AIM

To compare the biomechanical properties of three different sternal closure techniques in a 3D-printed bone model of a sternum from a 30-kg dog.

METHODS

Median sternotomy was performed on a total of 90 three-dimensional (3D) copies of a polycarbonate (PC) model of a sternum, generated from the CT images of the sternum of a 30-kg German Shepherd dog. Three different methods were used to repair the sternotomies: polydioxanone suture (group PDS, n = 30), stainless steel bone staples (group SS, n = 30), and nitinol bone staples (group NS, n = 30). Each repair method was tested by applying tensile force in one of three ways (longitudinally, laterally, or torsionally) resulting in a sample size of n = 10 for each repair method-loading combination. In all experiments, the loads at 1-mm and 2-mm gap formation, failure, and the displacement at the failure point were measured.

RESULTS

In lateral distraction and longitudinal shear tests, NS and SS staple repairs required application of significantly greater force than PDS across all displacement criteria (1 and 2 mm). NS exhibited significantly greater failure load than PDS. In torsion tests, NS required significantly greater application of force compared to SS or PDS at all displacement criteria (1 and 2 mm) and exhibited a greater failure load than PDS. In terms of displacement at failure point, PDS suture showed more displacement than SS or NS across all experiments (laterally, longitudinally, torsionally).

CONCLUSIONS

In this study, bone staples were mechanically superior to PDS suture in median sternotomy closure using 3D-printed bone model in terms of 1-mm, 2-mm displacement loads, and displacement at failure. NS had a higher failure load than PDS under lateral, longitudinal, and torsional distraction.

CLINICAL RELEVANCE

These study results imply that bone staples can be considered as an alternative surgical method for median sternotomy closure in dogs.

Biomechanical comparison of canine median sternotomy closure using suture tape and orthopedic wire cerclage

OBJECTIVE

To compare the mechanical properties of suture tape and orthopedic wire cerclage in an ex vivo canine median sternotomy model.

STUDY DESIGN

Ex vivo.

ANIMALS

Twelve large-breed canine cadaveric sternums.

METHODS

Median sternotomies were performed, leaving the manubrium intact. The specimens were randomly assigned to group W (20-gauge stainless steel orthopedic wire cerclage in a figure-of-eight pattern) or group ST (suture tape in a figure-of-eight pattern). Each specimen was laterally distracted until failure using an electrodynamic materials-testing system.

RESULTS

No differences were observed for displacement, yield load, maximum load, implant failure between the groups. The orthopedic wire construct was stiffer than the suture tape construct.

CONCLUSION

Suture tape was biomechanically similar to orthopedic wire cerclage for sternotomy closure in dogs, although wire constructs were stiffer.

CLINICAL SIGNIFICANCE

Suture tape may represent an alternative to cerclage wire for sternotomy closure in dogs. Additional studies evaluating its clinical use are needed.

Comparison of median sternotomy closure-related complication rates using orthopedic wire or suture in dogs: A multi-institutional observational treatment effect analysis

Objective

To determine and compare median sternotomy (MS) closure‐related complication rates using orthopedic wire or suture in dogs.

Study design

Multi‐institutional, retrospective observational study with treatment effect analysis.

Animals

331 client‐owned dogs, of which 68 were excluded.

Methods

Medical records of dogs with MS were examined across nine referral centers (2004–2020). Signalment, weight, clinical presentation, surgical details, complications, and outcomes were recorded. Follow‐up was performed using patient records and email/telephone contact. Descriptive statistics, treatment effect analysis and logistic regression were performed.

Results

Median sternotomy closure was performed with wire in 115 dogs and suture in 148. Thirty‐seven dogs experienced closure‐related complications (14.1%), 20 in the wire group and 17 in the suture group. Twenty‐three were listed as mild, four as moderate and 10 as severe. Treatment effect analysis showed a mean of 2.3% reduction in closure‐related complications associated with using suture versus wire (95% CI: −9.1% to +4.5%). In multivariable logistic regression, the only factor associated with increased risk of closure‐related complications was dog size (p = .01). This effect was not modified by the type of closure used (interaction term: OR = 0.99 [95% CI: 0.96/1.01]).

Conclusion

The incidence of closure‐related complication after MS was low compared to previous reports. The likelihood of developing a closure‐related complication was equivalent between sutures and wires, independent of dog size, despite a higher proportion of complications seen in larger dogs (≥20 kg).

Clinical significance

Use of either orthopedic wire or suture appear to be an appropriate closure method for sternotomy in dogs of any size.

Closure-related complications after median sternotomy in cats: 26 cases (2010-2020)

OBJECTIVES

The aim of this study was to determine closure-related complications and outcome after median sternotomy (MS) in cats.

METHODS

This was a retrospective, multicentric study. The medical records of cats undergoing MS from six referral hospitals were reviewed (2010-2020). Data retrieved included signalment, history, presenting complaints, surgery, patient outcomes and complications. Follow-up was performed via patient records and email/telephone contact with both owners and referring veterinarians. Descriptive statistics were performed.

RESULTS

Data on 36 cats were collected; four were excluded due to insufficient follow-up and six died less than 5 days after surgery. Twenty-six cats survived to discharge (survival rate 81%). Three cats had a full sternotomy (FS) performed and 23 cats a partial sternotomy (PS). Of the cats that underwent a PS, six included the manubrium (PSM) and three included the xyphoid process. For 14 cats, the length of sternotomy was unknown. Sternotomy closure was performed with suture in all cats. Two cats (7.7%) developed closure-related complications, both after PSM, during the long-term follow-up, one mild, slightly displaced sternal fracture and one severe, sternal dehiscence (without skin wound dehiscence) requiring revision surgery. No seroma, surgical site infection or wound dehiscence occurred. The most common reason for MS was the presence of a thoracic mass (17/26; 65%), with thymoma being the most common (11/17; 65%).

CONCLUSIONS AND RELEVANCE

MS has a low closure-related complication risk in cats when compared with dogs. Complications in cats present differently to what has been previously described in dogs.

Crimped monofilament nylon leader for median sternotomy closure in 10 dogs

OBJECTIVE

To describe and report the outcomes after closure of median sternotomies with crimped monofilament nylon leader (MNL) in dogs.

STUDY DESIGN

Retrospective observational study.

ANIMALS

Dogs (n = 10) that underwent intrathoracic surgery through a median sternotomy approach.

METHODS

The median sternotomy was closed in a peristernal figure eight pattern with crimped MNL. Medical records were reviewed for clinical and histopathological findings and complications. Owners or veterinarians were contacted to collect long-term follow-up information.

RESULTS

The technique was simple, with no intraoperative complications. Postoperative infection was documented in one dog, requiring removal of a single MNL and associated crimp clamp. Delayed healing of the surgical incision in one dog was managed conservatively. No other complications were documented throughout long-term follow-up at a median of 488 days (range, 199-608).

CONCLUSION

Median sternotomies were successfully closed with crimped MNL and were associated with a low complication rate.

CLINICAL SIGNIFICANCE

Crimped MNL represents an alternative method to close median sternotomies in dogs.