Can we improve fixation and outcomes in the treatment of femoral neck fractures? The use of pharmaceuticals

Bisphosphonate use in the horse: what is good and what is not?

Background

Bisphosphonates (BPs) are a family of molecules characterized by two key properties: their ability to bind strongly to bone mineral and their inhibitory effects on mature osteoclasts and thus bone resorption. Chemically two groups of BPs are recognized, non-nitrogen-containing and nitrogen-containing BPs. Non-nitrogen-containing BPs incorporate into the energy pathways of the osteoclast, resulting in disrupted cellular energy metabolism leading to cytotoxic effects and osteoclast apoptosis. Nitrogen-containing BPs primarily inhibit cholesterol biosynthesis resulting in the disruption of intracellular signaling, and other cellular processes in the osteoclast.

Body

BPs also exert a wide range of physiologic activities beyond merely the inhibition of bone resorption. Indeed, the breadth of reported activities include inhibition of cancer cell metastases, proliferation and apoptosis in vitro. In addition, the inhibition of angiogenesis, matrix metalloproteinase activity, altered cytokine and growth factor expression, and reductions in pain have been reported. In humans, clinical BP use has transformed the treatment of both post-menopausal osteoporosis and metastatic breast and prostate cancer. However, BP use has also resulted in significant adverse events including acute-phase reactions, esophagitis, gastritis, and an association with very infrequent atypical femoral fractures (AFF) and osteonecrosis of the jaw (ONJ).

Conclusion

Despite the well-characterized health benefits of BP use in humans, little is known regarding the effects of BPs in the horse. In the equine setting, only non-nitrogen-containing BPs are FDA-approved primarily for the treatment of navicular syndrome. The focus here is to discuss the current understanding of the strengths and weaknesses of BPs in equine veterinary medicine and highlight the future utility of these potentially highly beneficial drugs.

Bone healing in 2016

Delayed fracture healing and nonunion occurs in up to 5-10% of all fractures, and can present a challenging clinical scenario for the treating physician. Methods for the enhancement of skeletal repair may benefit patients that are at risk of, or have experienced, delayed healing or nonunion. These methods can be categorized into either physical stimulation therapies or biological therapies. Physical stimulation therapies include electrical stimulation, low-intensity pulsed ultrasonography, or extracorporeal shock wave therapy. Biological therapies can be further classified into local or systemic therapy based on the method of delivery. Local methods include autologous bone marrow, autologous bone graft, fibroblast growth factor-2, platelet-rich plasma, platelet-derived growth factor, and bone morphogenetic proteins. Systemic therapies include parathyroid hormone and bisphosphonates. This article reviews the current applications and supporting evidence for the use of these therapies in the enhancement of fracture healing.

Is Disuse Osteopenia a Favorable Prognostic Sign After Femoral Neck Fracture?

OBJECTIVES

Avascular necrosis (AVN) of the femoral head is a devastating complication following fixation of femoral neck fractures in younger adults. In this study, we investigate the prognostic utility of disuse osteopenia.

DESIGN

Retrospective study.

SETTING

Three academic Level 1 trauma centers.

PATIENTS

One hundred twenty patients younger than 60 years treated for a femoral neck fracture.

INTERVENTION

N/A.

MAIN OUTCOME MEASURES

The presence of sclerosis or osteopenia, compared to the contralateral femoral head, was measured 6 weeks from injury both subjectively and using a novel radiographic measure, the relative density ratio (RDR). The outcome measure was radiographic development of AVN.

RESULTS

The presence of relative sclerosis was associated with AVN and overall treatment failure. Patients with subjective relative sclerosis had a 12.6 (95% confidence interval, 2.9-61.3; P < 0.001) times higher odds of developing AVN. Multiple logistic regression showed that for every 0.10 increase in the RDR, there was a 5.2 increase in the odds (95% confidence interval, 2.1-26.9; P = 0.009) of developing AVN. Patients with an RDR of ≥1.2 have an 80% probability of AVN, whereas those with an RDR ≤0.8 have a <1% probability of developing AVN.

CONCLUSIONS

Disuse osteopenia detected on 6-week radiographs is a favorable prognostic sign following fixation of femoral neck fractures. Patients who have relative sclerosis of the femoral head at 6-week follow-up are at a higher risk of developing AVN.

LEVEL OF EVIDENCE

Diagnostic Level III. See Instructions for Authors for a complete description of levels of evidence.

Strontium ranelate as an adjuvant for fracture healing: clinical, radiological, and ultrasound findings in a randomized controlled study on wrist fractures

This randomized and controlled study evaluated the effect of therapy with strontium ranelate on callus formation in wrist fractures and its incidence in wrist recovery. Radiographic healing, progression of clinical recovery, and callus quality with ultrasound were evaluated. No statistically significant benefit of therapy was found.

INTRODUCTION

Fracture prevention is the main goal of any therapy for osteoporosis. Various drugs used in osteoporosis treatment have the theoretical premises to promote fracture healing and osseointegration. In this study, the effect of strontium ranelate on callus formation in wrist fractures was evaluated and whether it could lead to clinically relevant modification of wrist recovery; having strontium ranelate osteoinductive properties, it could be used, if effective, as an adjunct in fracture healing for a faster and functionally better recovery and, at the same time, in starting proper therapy in osteoporotic patients with fragility fractures.

METHODS

We considered only patients older than 60 years who had suffered wrist fracture and received nonoperative treatment with manual reduction of the fracture and cast for 35 days. Forty patients were included and randomly assigned to one of two groups: group A [patients treated with calcium (1200 mg/day) and vitamin D (800 IU/day)] and group B [patients treated with calcium (1200 mg/day) and vitamin D (800 IU/day) associated with strontium ranelate 2 g daily]. Radiographic healing was evaluated through the bone callus formation, cortical continuity, and density of the callus. A clinical evaluation using Castaing's criteria was carried out 2 and 3 months following the fracture together with an ultrasound study of callus density and vessels.

RESULTS

A parametric analysis of the X-ray data, clinical evaluation, and ultrasonography results showed that there were no statistically significant differences in the two groups (p > 0.05 for all data).

CONCLUSION

In analyzing the data obtained, we concluded that strontium ranelate administered in acute phase did not improve nor accelerate wrist fracture healing in our population.

Bone augmentation using a new injectable bone graft substitute by combining calcium phosphate and bisphosphonate as composite--an animal model

Objective

The aim of this study was to create a new injectable bone graft substitute by combining the features of calcium phosphate and bisphosphonate as a composite bone graft to support bone healing and to evaluate the effect of alendronate to the bone healing process in an animal model.

Material and method

In this study, 24 New Zealand white rabbits were randomly divided into two groups: a calcium phosphate alendronate group and a calcium phosphate control group. A defect was created at the proximal medial tibia and filled with the new created injectable bone graft substitute calcium phosphate alendronate or with calcium phosphate. Healing process was documented by fluoroscopy. To evaluate the potential of the bone graft substitute, the proximal tibia was harvested 2, 4, and 12 weeks after operation. Histomorphological analysis was focused on the evaluation of the dynamic bone parameters using the Osteomeasure system.

Results

Radiologically, the bone graft materials were equally absorbed. No fracture was documented. The bones healed normally. After 2 weeks, the histological analysis showed an increased new bone formation for both materials. The osteoid volume per bone volume (OV/BV) was significantly higher for the calcium phosphate group. After 4 weeks, the results were almost equal. The trabecular thickness (Tb.Th) increased in comparison to week 2 in both groups with a slight advantage for the calcium phosphate group. The total mass of the bone graft (KEM.Ar) and the bone graft substitute surface density (KEM.Pm) were consistently decreasing. After 12 weeks, the new bone volume per tissue volume (BV/TV) was still constantly growing. Both bone grafts show a good integration. New bone was formed on the surface of both bone grafts. The calcium phosphate as well as the calcium phosphate alendronate paste had been enclosed by the bone. The trabecular thickness was higher in both groups compared to the first time point.

Conclusion

Calcium phosphate proved its good potential as a bone graft substitute. Initially, the diagrams seem to show a tendency that alendronate improves the known properties of calcium phosphate as a bone graft substitute. The composite graft induced a good and constant new bone formation. Not only the graft was incorporated into the bone but also a new bone was formed on its surface. But we could not prove a significant difference between the grafts. Both implants proved their function as a bone graft substitute, but the bisphosphonate alendronate does not support the bone healing process sufficiently that the known properties of calcium phosphate as a bone graft substitute were improved in the sense of a composite graft. In this study, alendronate used as a bone graft in a healthy bony environment did not influence the bone healing process in a positive or negative way.

Should full threaded compression screws be used in adult femoral neck fractures?

INTRODUCTION

Operative treatment consisting of fracture reduction and fixation, or arthroplasty to permit early patient mobilization, continues to be the treatment of choice for most femoral neck fractures. Options for internal fixation have included a variety of implants; however most recent reports and textbooks cite parallel multiple cancellous screws as the surgical technique of choice.

METHODS

The study was prospective, randomized and IRB approved. Inclusion criteria included skeletal maturity, closed femoral neck fracture without concomitant fractures or injuries with complete charts and adequate radiographs obtained from the initial injury till the last follow-up. Forty-four patients were enrolled in this study during one-year period at two university centers. 22 were randomized to be treated with full threaded, cannulated compression screws (Acutrak 6/7, ACUMED) (Group 1) and the other 22 with 16mm partial threaded, 6.5mm or 7.3mm cannulated screws (SYNTHES) (Group 2). Three or four screws were used in both groups according to fracture type and surgeon's preference. Data evaluated included surgical time, fluoroscopy time, fracture type, radiological outcome, complications and functional status using the Harris Hip Score.

RESULTS

Both groups were comparable in terms of age and gender. There was not a significant difference in terms of surgical time, follow-up period, fracture type, or fluoroscopy time. There were eight complications in Group 1 and two in Group 2 (P=0.049) Time to union was significantly longer in Group 1 (P=0.001). However, Hip Scores were not significantly different in both groups (P=0.20).

CONCLUSION

When compared with full threaded compression screws, partial-threaded cannulated screws provides a shorter union time and less complication rate while providing equivalent functional results in adult femoral neck fractures.

Hollow-bone-graft dynamic hip screw can fix and promote bone union after femoral neck fracture: an experimental research

BACKGROUND

Delayed bone union, nonunion or osteonecrosis often occur after femoral neck fractures in young adults. Secondary bone healing requires strong internal fixation, intramedullary pressure reduction and early functional exercise.

OBJECTIVE

To compare bone healing of femoral neck fractures treated with hollow-bone-graft dynamic hip screws (Hb-DHS) and standard dynamic hip screws (DHS) in an animal model.

DESIGN

Testing of specifically designed fixation devices in a pig animal model.

INTERVENTIONS/METHODS

We designed Hb-DHS and DHS devices appropriate to the femoral neck and head of experimental animals and used them in eight pigs (4-month-old, male or female, 30-40 kg/each). Under anesthesia, we induced medium neck type, Garden III type femoral neck fractures in each pig with fracture gaps of 0.5 mm and then fixed each left femur with Hb-DHS and each right femur with DHS. We assessed the animals radiographically and by postmortem visual appraisal of evidence of bone healing 8 and 16 weeks postoperatively.

RESULTS

There were significant differences in radiographic and general findings between the Hb-DHS and DHS groups at weeks 8 and 16 postoperatively. We found statistically significant differences between the Hb-DHS and DHS groups in bone healing scores, trabecular bone volume percentage and bone mineral density as assessed on plain radiographs and computed tomography images (P < 0.05). There were also significant differences between the Hb-DHS and DHS groups in postmortem visually assessed indicators of bone healing at both 8 and 16 weeks postoperatively.

CONCLUSIONS

The Hb-DHS device promotes femoral neck bone union, stimulates trabecular bone formation, increases BMD and has advantages over DHS for internal fixation of femoral neck fractures. This animal experiment will contribute to developing optimal treatment for femoral neck fractures in young adults.