Structural integrity of intramedullary rib fixation using a single bioresorbable screw

Finite element analysis of different fixation methods of screws on absorbable plate for rib fractures

Multiple rib fractures caused by trauma are common injuries and the internal fixation methods of these injuries have been paid more and more attention by surgeons. Absorbable plates and screws are the effective way to treat rib fractures, but there are no reports on which type of screw fixation method is most effective. In this study, finite element analysis was used to study the effects of five different types of screw fixation methods on anterior rib, lateral rib and posterior rib. The finite element model of the ribs was reconstructed from CT images, and the internal pressure (40 kPa) and intercostal force (30 N) on the surfaces of the ribs were simulated accordingly. An intercostal force of 30 N was applied to the upper and lower surfaces of the ribs to simulate the effect of intercostal muscle force. The pressure of 40 kPa was applied to the inner surface of the ribs, and the normal direction was applied to the inner surface of the ribs. The positive direction was considered inspiratory pressure, and the negative direction was considered expiratory pressure. The results indicate the optimal type of screw fixation on the absorbable plate for rib fractures, and provide a basis and reference for clinical application.

Prospective Randomized Trial of Metal vs Resorbable Plates in Surgical Stabilization of Rib Fractures

INTRODUCTION

Surgical stabilization of rib fractures has gained popularity as both metal and resorbable plates have been approved for fracture repair. Is there a difference between metal and resorbable plate rib fixation regarding rib fracture alignment, control of pain, and quality-of-life scores (Rand SF-36 survey)?

METHODS

Eligible patients (pts) included ≥18 years with one or more of the following: flail chest, one or more bi-cortical displaced fractures (3 -10), non-displaced fractures with failure of medical management. Pts were randomized to either metal or resorbable plate fixation. Primary outcome was fracture alignment. Secondary outcomes were pain scores, opioid use and QOL scores.

RESULTS

30 pts were randomized (15 metal/15 resorbable). Total ribs plated 167 (88 metal/79 resorbable). Pts with rib displacement at day of discharge (DOD) metal 0/14 (1 pt died, not from plating) vs resorbable 9/15 or 60% (p = .001). Ribs displaced at DOD metal 0/88 vs resorbable 22/79 or 28% (p < .001), 48% in posterior location. Pts with increased rib displacement 3-6-months: metal 0/11 vs resorbable 3/9 or 33% (p = .043). Ribs with increased displacement 3-6-months metal 0/67 vs resorbable 6/49 or 12.2% (p < .004). Pain scores & narcotic use at post-op day 1, 2, 3, DOD, 2 wks, 3 and 6 months showed no statistically significant difference between groups. QOL scores were also similar at 3 and 6 months. Trauma recidivism in outpatient period resulted in fracture of resorbable plates in 2 pts requiring a second surgery.

CONCLUSION

Metal plates provided better initial alignment with no displacement over time. Clinical outcomes were similar regarding pain, narcotic use & QOL scores. Routine use of resorbable plates for posterior rib fractures is not warranted. Lateral repairs were technically most feasible for using resorbable plates but still resulted in significant displacement. Resorbable plates may not maintain rib alignment when exposed to subsequent injury.

LEVEL OF EVIDENCE

Level II, therapeutic.

A Randomized Controlled Trial of Surgical Rib Fixation in Polytrauma Patients With Flail Chest

BACKGROUND

Flail chest (FC) is known to account for high mortality and morbidity and is typically treated with conservative care. Operative fixation of FC has been advocated as an alternative treatment choice. This prospective randomized controlled trial aims to compare surgical and nonsurgical management of FC in patients with severe polytrauma.

METHODS

Severe polytrauma patients with FC admitted between January 2015 and July 2017 to our trauma center were investigated. The enrolled patients were randomly assigned to the surgical or nonsurgical group. Basic characteristics of injury and clinical outcomes were compared.

RESULTS

Fifty patients entered final analysis, with 25 patients in each group. Operative rib fixation was associated with shorter duration of mechanical ventilation (7 d [interquartile range {IQR} 6-10] versus 9 d [IQR 7-12], P = 0.012), shorter ICU stay (10 d [IQR 7-12] versus 12 d [IQR 9-15], P = 0.032), lower risk of adult respiratory distress syndrome (28% versus 60%, P = 0.045), pneumonia (48% versus 80%, P = 0.038), and thoracic deformity (8% versus 36%, P = 0.037) and less pain while coughing (pain score 6 [IQR 3-8] versus 8 [IQR 4-9], P = 0.029) and deep breathing (pain score 5 [IQR 3-9] versus 7 [IQR 3-9], P = 0.038). Subgroup analysis was conducted by presence of pulmonary contusion. Shorter time on the ventilator use and ICU stay associated with rib surgery was not observed in patients with pulmonary contusion.

CONCLUSIONS

This study reveals that surgical rib fixation may provide some critical care benefits for severe polytrauma patients with FC, including less medical resource use and lower risk of complications. Further studies should be designed to optimally identify patients who are most likely to benefit from this surgery.

Development of a socket-type rib coaptation device made of poly-L-lactide fibers: feasibility study in a canine model

Background

Costal coaptation pins made of poly-L-lactide (PLA) are clinically available for fixing surgically divided ribs. However, the clinical results of such rib fixation have not been completely satisfactory. We aimed to develop a new rib coaptation socket system and explore its clinical applicability.

Methods

We surgically divided three consecutive ribs of each beagle dog, and rib coaptation sockets were implanted to stabilize each rib. Fifteen 3-dimensional (3D)-printed and 30 PLA fiber knitted sockets were implanted in five and ten dogs, respectively, to stabilize the artificially divided ribs. Mechanical analysis of the sockets and radiographical examination of costal fixation were performed to evaluate the effectiveness of the newly developed socket system for rib stabilization.

Results

All 15 ribs with 3D-printed sockets had displaced 1 month after the operation. Three ribs in one dog with implanted PLA fiber knitted sockets were displaced radiographically after 1 month, and the grade of displacement remained unchanged after 6 months. The remaining 27 ribs fixed with PLA fiber knitted sockets did not show any displacement.

Conclusions

The PLA fiber knitted rib coaptation socket system was sufficiently durable for the stabilization of divided ribs with biocompatibility. This promising finding can be applied for clinical stabilization of divided ribs.

Chest Wall Trauma

Chest wall trauma is common, and contributes significantly to morbidity and mortality of trauma patients. Early identification of major chest wall and concomitant intrathoracic injuries is critical. Generalized management of multiple rib fractures and flail chest consists of adequate pain control (including locoregional modalities); management of pulmonary dysfunction by invasive and noninvasive means; and, in some cases, surgical fixation. Multiple studies have shown that patients with flail chest have substantial benefit (decreased ventilator and intensive care unit days, improved pulmonary function, and improved long-term functional outcome) when they undergo surgery compared with nonoperative management.

An assessment of outcomes with intramedullary fixation of fractured ribs

BACKGROUND

Surgical management of fractured ribs with internal fixation is an increasingly accepted therapy. Concurrently, specific rib fixation prostheses are being developed which should improve results and minimise hardware and rib/splint construct failures. The Synthes titanium intramedullary splint lends itself to difficult to access areas such as posterior rib fractures and fractures under the scapula. We analyse a case series of patients in whom this rib fixation prosthesis has been used.

METHODS

Fifteen patients received 35 intramedullary splints. Follow up at 3 and 6 months was performed with three dimensional computed tomography scanning to assess for bone alignment, callus formation and healing, residual deformity, hardware failure or cut through. Computerized finite element analysis (FEA) was used to model forces acting on a posterior fracture with and without an intramedullary fixation splint in situ.

RESULTS

Complete healing (bony union) was noted in only 3 (9 %) of the fractures fixed with splints by 3 months. Partial healing (cartilaginous union) was noted in 28 of the 33 fractures (85 %), and non healing was noted in only 2 (6 %). In both those two patients, failure at the rib / splint interface was noted after both patients reported sneezing. No hardware failures were noted. By 6 months the fractures which had shown partial healing, had all completely healed. There were no late failures (between 3 and 6 months) of either hardware or rib/splint interfaces. FEA modelling identified sites of increased stress in the rib at the rib / splint interface and in a modelled intramedullary splint where it spans the fracture.

CONCLUSIONS

Further analysis of outcomes with intramedullary splints is warranted as well as further development of intramedullary rib fixation solutions.

[Unstable thorax fixation with bioabsorbable plates and screws. Presentation of some cases]

BACKGROUND

Flail chest is managed with mechanical ventilation or inhalation therapy, and analgesia. Mechanical ventilations carry risks by themselves and disengage with the external fixators so they must be operated to improve lung ventilatory mechanics and cleaning. Little has been published on the use of bioabsorbable material and its evolution in the setting of flail chest.

MATERIAL AND METHODS

A material that did had to be retired, that presented the malleability of titanium and its inflammatory reaction was minimal and could be handled in both adults and children was investigated. Here is shown a descriptive study of patients with flail chest under rib fixation with plates and bioabsorbable screws.

RESULTS

18 cases are presented, aged 33-74 years, three with bilateral flail chest; fixation was performed between days 1-21 of the accident. In cases that showed no fractures pelvic limbs, gait next day restarted fi ng in all cases improved mechanical ventilation, pain decreased, none has so far presented reaction material.

CONCLUSIONS

Flail chest has a high (16.3%) mortality when no management provides the pathophysiology of the condition (pain, poor mechanical ventilation, alveolar edema-pulmonary contusion). The use of bioabsorbable material has no side effects attributable to material which is another option for rib fixation.

Displacement Patterns of Blunt Rib Fractures and Their Relationship to Thoracic Coinjuries: Minimal Displacements Count

Displacement patterns of rib fractures (RF) and their association with thoracic coinjuries and outcomes are unknown. This is a retrospective review of adult patients with blunt closed RF who underwent chest CT at a Level I trauma center (2007–2012). Displacement patterns of RF were compared among the three-dimensional planes using CT images. An analysis of receiver operating characteristic (ROC) curves was performed to identify displacements in each plane most strongly associated with chest coinjuries. Univariate analysis was used to find association of displaced RF with hospital course and outcome. There were 1127 RF (245 patients, most in ribs 3–9, 45 per cent displaced). Axial displacement was the most common, with odds ratios 7.20 and 2.13 compared with cranio-caudal, and impaction-separation (along rib axis) movement, respectively. Axial displacement thresholds performed well with hemothorax (2.8 mm, ROC = 0.74), pneumothorax (2.6 mm, ROC = 0.70), hemopneumothorax (3.1 mm, ROC = 0.77), flail chest (3.4 mm, ROC = 0.80), and chest tube placement (2.8 mm, ROC = 0.75). RF displacement was associated with increased days on mechanical ventilation and hospital length of stay. In conclusion, even minimal RF displacement is associated with increased risk of chest coinjuries and chest tube placement, and displacements correlated with increased days on mechanical ventilation and hospital length of stay. Future studies are required to investigate these associations, especially in relationship to the indications for rib plating.

Fixation of a human rib by an intramedullary telescoping splint anchored by bone cement

A novel concept for rib fixation is presented that involves the use of a bioresorbable polymer intramedullary telescoping splint. Bone cement is used to anchor each end of the splint inside the medullary canal on each side of the fracture site. In this manner, rib fixation is achieved without fixation device protrusion from the rib, making the splint completely intramedullary. Finite element analysis is used to demonstrate that such a splint/cement composite can preserve rib fixation subjected to cough-intensity force loadings. Computational fluid dynamics and porcine rib experiments were used to study the anchor formation process required to complete the fixation.

Potential Benefits of Rib Fracture Fixation in Patients with Flail Chest and Multiple Non-flail Rib Fractures

The purpose of this study is to evaluate the potential benefits of rib fracture fixation in patients with flail chest and multiple non-flail rib fractures versus conventional treatment modalities. A retrospective reviewed study compared 86 cases which received surgical treatment between June 2009 and May 2013 to 76 cases which received conservative treatment between January 2006 and May 2009. The patients were divided into the flail chest (n = 38) and multiple non-flail rib fracture groups (n = 124). In the flail chest group, the mechanical ventilation time, ICU monitoring time, tracheostomies, thoracic deformity, and impaired pulmonary function and return to full-time employment were compared. In the multiple non-flail rib fracture group, fracture healing, visual analog scale (VAS) pain score, inpatient length of stay, atelectatic, pulmonary complications, and normal activity-returning time were compared. Patients in the flail chest operative fixation group had significantly shorter ICU stay, decreased ventilator requirements, fewer tracheostomies, less thoracic deformity and impaired pulmonary function, and more returned to full-time employment. Patients in the multiple non-flail rib fracture operative fixation had shorter hospital stay, less pain, earlier return to normal activity, more fracture healing, less atelectasis, and fewer pulmonary infections. This study demonstrates the potential benefits of surgical stabilization of flail chest and multiple non-flail rib fractures with plate fixation. When compared with conventional conservative management, operatively managed patients demonstrated improved clinical outcomes.

A Novel Biodegradable Polycaprolactone Fixator for Osteosynthesis Surgery of Rib Fracture: In Vitro and in Vivo Study

Osteosynthesis surgery for rib fractures is controversial and challenging. This study developed a noval poly(ε-caprolactone) (PCL)-based biodegradable “cable-tie” fixator for osteosynthesis surgery for rib fractures. A biodegradable fixator specifically for fractured ribs was designed and fabricated by a micro-injection molding machine in our laboratory. The fixator has three belts that could be passed through matching holes individually. The locking mechanism allows the belt movement to move in only one direction. To examine the in vitro biomechanical performance, ribs 3–7 from four fresh New Zealand rabbits were employed. The load to failure and stress-strain curve was compared in the three-point bending test among native ribs, titanium plate-fixed ribs, and PCL fixator-fixed ribs. In the in vivo animal study, the sixth ribs of New Zealand rabbits were osteotomized and osteosynthesis surgery was performed using the PCL fixator. Outcomes were assessed by monthly X-ray examinations, a final micro-computed tomography (CT) scan, and histological analysis. The experimental results suggested that the ribs fixed with the PCL fixator were significantly less stiff than those fixed with titanium plates (p < 0.05). All ribs fixed with the PCL fixators exhibited union. The bridging callus was confirmed by gross, radiographic micro-three-dimensional (3D) CT, and histological examinations. In addition, there was no significant inflammatory response of the osteotomized ribs or the PCL-rib interface during application. The novel PCL fixator developed in this work achieves satisfactory results in osteosynthesis surgery for rib fractures, and may provide potential applications in other orthopedic surgeries.