Currents of plate osteosynthesis in osteoporotic bone

Biomechanical Variability and Usability of a Novel Customizable Fracture Fixation Technique

A novel in situ customizable osteosynthesis technique, Bonevolent™ AdhFix, demonstrates promising biomechanical properties under the expertise of a single trained operator. This study assesses inter- and intra-surgeon biomechanical variability and usability of the AdhFix osteosynthesis platform. Six surgeons conducted ten osteosyntheses on a synthetic bone fracture model after reviewing an instruction manual and completing one supervised osteosynthesis. Samples underwent 4-point bending tests at a quasi-static loading rate, and the maximum bending moment (BM), bending stiffness (BS), and AdhFix cross-sectional area (CSA: mm²) were evaluated. All constructs exhibited a consistent appearance and were suitable for biomechanical testing. The mean BM was 2.64 ± 0.57 Nm, and the mean BS was 4.35 ± 0.44 Nm/mm. Statistically significant differences were observed among the six surgeons in BM (p < 0.001) and BS (p = 0.004). Throughout ten trials, only one surgeon demonstrated a significant improvement in BM (p < 0.025), and another showed a significant improvement in BS (p < 0.01). A larger CSA corresponded to a statistically significantly higher value for BM (p < 0.001) but not for BS (p = 0.594). In conclusion, this study found consistent biomechanical stability both across and within the surgeons included, suggesting that the AdhFix osteosynthesis platform can be learned and applied with minimal training and, therefore, might be a clinically viable fracture fixation technique. The variability in BM and BS observed is not expected to have a clinical impact, but future clinical studies are warranted.

Lessons learned with the Cobra prosthesis in elderly patients with complex distal radius fractures-a retrospective follow-up study

INTRODUCTION

Recently, the Cobra prostheses were introduced in the treatment of distal radius fractures (DRF) of elderly patients. Fracture prostheses provide an alternative treatment option for complex fractures where conservative therapy seems not acceptable and osteosynthesis seems not possible. Data reporting the feasibility of the Cobra prosthesis are sparse. Therefore, this retrospective follow-up study investigated the clinical and radiological mid-term outcome of the Cobra implant in complex DRFs of elderly patients.

MATERIALS AND METHODS

Thirteen patients (mean age 73.5 years, range 65-87 years) were retrospectively evaluated with at least a 1-year follow-up after surgery. Objective and subjective clinical parameters as well as the radiological outcome and complications were analyzed.

RESULTS

The mean follow-up period was 31.2 months. Seven cases required a cemented prosthesis. The mean relative range-of-motion compared to the healthy side was 72.3% and 51.8% for extension and flexion, respectively, and 87.9% and 85.7% for pronation and supination, respectively. The mean grip strength was 78.3% compared to the non-operated side. Eight patients were very satisfied, five patients were partly satisfied with the result. The DASH, PRWE, MHQ and Lyon-Scores averaged 39.1, 36.2, 64.9 and 63.3 points, respectively. The mean VAS-Score for pain was 1.1 at rest and 3.2 during activities. Perioperative complications included one dissection of the extensor pollicis longus tendon, one heterotopic ossification, one radiocarpal dislocation and two cases of an ulnar impaction syndrome due to implant subsidence.

CONCLUSION

The prosthetic treatment of complex DRFs in elderly patients with the Cobra implant led to clinically and radiologically satisfactory mid-term results. The Cobra prosthesis still does not represent a gold standard but can be regarded as a feasible salvage option for complex DRFs when osteosyntheses may not be possible and non-operative treatment will lead to further functional restrictions and wrist pain during performing activities of daily life in high functional demand patients.

Can barb thread design improve the pullout strength of bone screws?

AIMS

To draw a comparison of the pullout strengths of buttress thread, barb thread, and reverse buttress thread bone screws.

METHODS

Buttress thread, barb thread, and reverse buttress thread bone screws were inserted into synthetic cancellous bone blocks. Five screw-block constructs per group were tested to failure in an axial pullout test. The pullout strengths were calculated and compared. A finite element analysis (FEA) was performed to explore the underlying failure mechanisms. FEA models of the three different screw-bone constructs were developed. A pullout force of 250 N was applied to the screw head with a fixed bone model. The compressive and tensile strain contours of the midsagittal plane of the three bone models were plotted and compared.

RESULTS

The barb thread demonstrated the lowest pullout strength (mean 176.16 N (SD 3.10)) among the three thread types. It formed a considerably larger region with high tensile strains and a slightly smaller region with high compressive strains within the surrounding bone structure. The reverse buttress thread demonstrated the highest pullout strength (mean 254.69 N (SD 4.15)) among the three types of thread. It formed a considerably larger region with high compressive strains and a slightly smaller region with high tensile strains within the surrounding bone structure.

CONCLUSION

Bone screws with a reverse buttress thread design will significantly increase the pullout strength. Cite this article: Bone Joint Res 2021;10(2):105-112.

An experimental study on stress-shielding effects of locked compression plates in fixing intact dog femur

Background

In orthopedic application, stress-shielding effects of implant materials cause bone loss, which often induces porosis, delayed bone healing, and other complications. We aimed to compare the stress-shielding effects of locked compression plate (LCP) and limited-contact dynamic compression plate (LC-DCP) in dogs with plate-fixed femurs.

Methods

Bilateral intact femurs of 24 adult dogs were fixed by adult forearm 9-hole titanium plates using minimally invasive plate osteosynthesis (MIPPO) technology, with LCP on the left and LC-DCP on the right femurs. Dogs were sacrificed at 6 weeks, 12 weeks, and 24 weeks after surgery, and bone specimens were used to evaluate the efficacies of different fixing methods on bones through X-ray, dual-energy X-ray absorptiometry (DEXA), histology, MicroCT, and biomechanics analyses.

Results

X-ray results showed significant callus formation and periosteal reaction in the LC-DCP group. Bone cell morphology, degree of osteoporosis, and bone mineral density (BMD) changes of the LCP group were significantly better than that of the LC-DCP group. MicroCT results showed that the LCP group had significantly reduced degree of cortical bone osteoporosis than the LC-DCP group. Tissue mineral density (TMD) in the LCP group was higher than that in the LC-DCP group at different time points (6 weeks, 12 weeks, and 24 weeks). Biomechanics analyses demonstrated that the compressive strength and flexural strength of bones fixed by LCP were better than that by LC-DCP.

Conclusions

Stress-shielding effects of LCP are significantly weaker than that of LC-DCP, which is beneficial to new bone formation and fracture healing, and LCP can be widely used in clinic for fracture fixation.

From creative thinking to scientific principles in clinical practice

Stephan Perren's contributions to the understanding and application of the principles of bone pathobiology, healing, and fracture fixation to clinical care remain as a lasting legacy of a great creative mind. Less well appreciated perhaps were his important contributions to the dissemination and practical application of those principles through the use of technology as applied to the learning environment. This paper describes and pays tribute to a series of initiatives in which Perren was a leading mentor and collaborator in the development of methods and instruments through which the principles of bone mechano-pathobiology could be translated through active learning environments into the practical world of clinical musculoskeletal traumatology.

Development and validation of a theory of planned behavior-based weight control behavior questionnaire among postmenopausal women with osteoporosis

Our aim was to develop a framework-based weight control behavior questionnaire (Weight-CuRB) and test its psychometric properties among a non-probability sample of 240 postmenopausal women with osteoporosis. Appropriate validity, simplicity, functionality and reliability were observed for the Weight-CuRB. The explanatory model fits the data well (χ2 [139] = 245.835, p < .001, CFI = 0.950, NFI = 0.901, IFI = 0.950, RMSEA = 0.057[(0.045-0.068]). To our knowledge, this was the first study to develop and validate a framework-based instrument aiming at cognitive needs assessment of postmenopausal women with osteoporosis. The weight-CuRB may be useful in addressing the core cognitive determinants of weight control among the patients.

[Osteoporotic bone fractures: intramedullary augmentation and hybrid osteosynthesis]

The increasing number of people who are living longer and have a far more active lifestyle is inevitably associated with greater numbers of fractures. Stabilization of these fractures in older patients with plates and screws is complicated by fragile bone substance, especially in osteoporotic bone, since osteosynthesis with a conventional plate depends exclusively on the holding power of the screws. Therefore, treatment requires new stabilization technologies designed for these specific tasks. A small diameter polyethylene terephthalate (PET, Dacron®) balloon is delivered in a minimally invasive fashion and placed within the canal, transversing the fracture. Once positioned, the balloon is expanded with a liquid monomer to fill the medullary canal. The liquid monomer is then rapidly cured using visible blue light, forming a patient-customized intramedullary implant that stabilizes the entire length of the bone in contact with the implant. The described intramedullary implant can be easily drilled in any position or location, providing a substantial increase in screw holding power. Thus, a major advantage of the technique is the possibility to augment the newly formed balloon "nail" with a conventional plate and screws at the primary stabilization or at any later time.

Optimization of screw fixation in rat bone with extracorporeal shock waves

Screw fixation in osteoporotic patients is becoming an increasing problem in orthopaedic surgery as deterioration of cortical and cancellous bone hamper biomechanical stability and screw fixation. This might result in delayed weight-bearing or failure of instrumentation. We hypothesized that local peri-operative shock wave treatment can optimize osseointegration and subsequent screw fixation. In eight female Wistar rats, two cancellous and two cortical bone screws were implanted in both femora and tibiae. Immediately after implantation, 3.000 unfocused extracorporeal shock waves (energy flux density 0.3 mJ/mm² ) were applied to one side. The other side served as non-treated internal control. Evaluation of osseointegration was performed after 4 weeks with the use of microCT scanning, histology with fluorochrome labeling, and pull-out tests of the screws. Four weeks after extracorporeal shock wave treatment, treated legs exhibited increased bone formation and screw fixation around cortical screws as compared to the control legs. This was corroborated by an increased pull-out of the shock wave treated cortical screws. The cancellous bone screws appeared not to be sensitive for shock wave treatment. Formation of neocortices after shock wave therapy was observed in three of eight animals. Furthermore, de novo bone formation in the bone marrow was observed in some animals. The current study showed bone formation and improved screw fixation as a result of shock wave therapy. New bone was also formed at locations remote from the screws, hence, not contributing to screw fixation. Further, research is warranted to make shock wave therapy tailor-made for fracture fixation. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:76-84, 2018.

Evaluation of locked plate in the osteosynthesis of fractures in osteoporotic bones

BACKGROUND

The use of conventional dynamic compression plates (DCPs) in osteoporotic bones is associated with higher chances of implant failure. The advent and use of locking combi-plates have ensured a stable construct during osteosynthesis of fractures in osteoporotic bones.

OBJECTIVES

The study aims to assess the outcome of use of locking combi-plates in the management of fractures in osteoporotic bones in our environment.

MATERIALS AND METHODS

Cases of patients with nonunion and localized osteoporosis from January 2014 to December 2014 that were managed with locked combi-plates were reviewed. Outcome was assessed by time to healing, stability of implant construct after 6 and 12 months.

RESULTS

There were 10 patients with mean age of 47.4 ± 12.63 years. There were 9 males and 1 female, and road traffic crashes were the mechanism of injury in 90% (n = 9) and gunshot injuries in 10% (n = 1). Atrophic nonunion was the most common indication for osteosynthesis with 80%, followed by fibrous nonunion with 10.0%. The humerus was the most common long bone involved with 50%. Locked broad DCP was used in 62.5%, and the duration between initial injury and surgery was 6 and 48 months, with an average of 17.5 months. The outcome was such that 90% healed after 12 months on follow-up while one case had the implant backing out and delay union at 6 months.

CONCLUSION

The use of locked plate in the management of nonunion in the presence of osteoporosis ensures stable fixation construct and healing. Contexte: L'utilisation de plaques de compression dynamiques conventionnelles dans les os ostéoporotiques est associée à des chances plus élevées de défaillance de l'implant. L'avènement et l'utilisation de combi-plaques de verrouillage ont assuré une construction stable lors de l'ostéosyntheis de fractures dans les os ostéoporotiques. Objectifs: L'étude vise à évaluer le résultat de l'utilisation de combi-plaques de verrouillage dans la gestion des fractures dans les os ostéoporotiques dans notre environnement. Méthodologie: Les cas de patients atteints d'ostéoporose non syndiquée et localisée de janvier 2014 à décembre 2014 qui ont été gérés avec des combi-plaques verrouillées ont été examinés. Le résultat a été évalué par le temps de guérison, la stabilité de la construction d'implant après 6 et 12 mois. Résultats: il y avait 10 patients avec un âge moyen de 47,4 12,63. Il y avait 9 hommes et 1 accident de la route et de la route était le mécanisme de la blessure dans 90% (n = 9) et les blessures par balle dans 10% (n = 1). La non-union atrophique était l'indication la plus courante pour l'ostéosynthèse avec 80%, suivie d'une non-union fibreuse avec 10,0%. L'humérus était l'os le plus fréquent impliqué avec 50%. La plaque de compression dynamique bloquée (DCP) a été utilisée à 62,5% et la durée entre la blessure initiale et la chirurgie était de 6 et 48 mois avec une moyenne de 17,5 mois. Le résultat était tel que 90% ont été guéris après 12 mois de suivi, tandis que 1 cas avait l'implantation de l'implant et retardé l'union à 6 mois.

CONCLUSION

L'utilisation de la plaque verrouillée dans la gestion de la non-union en présence d'ostéoporose assure une construction stable de fixation et une guérison.

The outcome of Polyax Locked Plating System for fixation distal femoral non-implant related and periprosthetic fractures

The objective of this study was to report on the safety, efficacy and clinical outcomes of the Polyax Locked Plating System (Biomet, Warsaw, IN, USA) in the management of acute (non-implant related and periprosthetic) distal femoral fractures. We retrospectively reviewed 71 patients with 73 distal femoral fractures. Thirty-three of the included fractures occurred around previously placed implants. The average patients' age was 67 years (range 18-98). There were 7 early postoperative complications (9.5%) including one deep surgical site infection, 2 pulmonary embolisms and 4 urinary or respiratory infections. At final follow-up (mean 12, range 9-55 months) all fractures progressed to clinical and radiological union. However, major revision surgery for healing problems was required in 5 cases (6.8%) and minor in 3 cases (4.1%). The average time to healing was 6 (range 3-23) months. Angulation less than 5 degrees in any plane was observed in 66 cases (89.7%), within 5-10 degrees in 5 cases (7.3%) and within 10-15 degrees in 2 cases (2.9%). The mean pre-injury and final follow-up values of Glasgow Outcome Scale were 1.5(1-3) and 1.7(1-3) respectively. Overall 61 patients (83.53%) retained their pre-injury activity status. The Polyax Locked Plating System offers a safe and efficient fixation in distal femoral fractures.