Preclinical evaluation of zoledronate to maintain bone allograft and improve implant fixation in revision joint replacement

Evaluation of Biocompatibility of New Osteoplastic Xenomaterials Containing Zoledronic Acid and Strontium Ranelate

Background. The problem of improving the functional characteristics of implanted devices and materials used in traumatology and orthopedics is a topical issue. Aim of the study to study biocompatibility of bovine bone matrix xenomaterials modified by zoledronic acid and strontium ranelate when implanted into the bone defect cavity. Methods. The study was performed on 24 male rabbits of the Soviet Chinchilla breed. Test blocks of bone matrix were implanted into the cavity of bone defects of the femur. Group 1 animals (n = 8, control group) were implanted with bone xenogenic material (Bio-Ost osteoplastic matrix). Group 2 animals (n = 8) were implanted with bone xenogenic material impregnated with zoledronic acid. Group 3 animals (n = 8) were implanted with bone xenogeneic material impregnated with strontium ranelate. Supercritical fluid extraction technology was used to purify the material and impregnate it with zoledronic acid and strontium ranelate. Radiological, pathomorphological, histological and laboratory (hematology and blood biochemistry) diagnostic methods were used to assess biocompatibility. Follow-up period was 182 days after implantation. Results. It was found out that on the 182nd day after implantation the median area of the newly-formed bone tissue in the defect modeling area in Group 1 was 79%, in Group 2 0%, in Group 3 67%. In Group 2 the maximum area by this period was filled with connective tissue 77%. Median relative area of implanted material fragments in Group 1 was 4%, in Group 2 23%, in Group 3 15%. No infection or material rejection was observed in animals of all groups. There were no signs of intoxication or prolonged systemic inflammatory reaction. Laboratory parameters did not change significantly over time. One animal in each group experienced one-time increase in C-reactive protein level against the background of leukocytosis. Two animals in Group 1 had a slight migration of implanted material under the skin, one animal developed arthritis of the knee joint. Conclusion. Osteoplastic materials based on bovine bone xenomatrix and filled with zoledronic acid and strontium ranelate have acceptable values of biocompatibility including their safety profile.

Does Local Zoledronate Applied to Pasteurized Bone Autografts Improve the Likelihood of Union of Graft-Host Junctions after Limb-sparing Surgery?

BACKGROUND

Pasteurized bone autograft is a recycling biological reconstruction method for limb-sparing surgery when an allograft or other reconstruction technique is unavailable. Since the application of a local bisphosphonate to morselized allografts can reduce graft resorption and enhance bone formation without systemic complications, adding the local bisphosphonate to pasteurized bone autografts should reduce the graft resorption and improve the graft incorporation to host bone. However, no study that we know of has described the outcomes of local bisphosphonate application to massive allografts or pasteurized bone autografts. Thus, this study compared the outcomes of pasteurized bone autografts with and without local zoledronate.

QUESTIONS/PURPOSES

(1) What is the survival of pasteurized bone autografts and what complications lead to graft removal? (2) Does treatment of pasteurized bone autografts with zoledronate alter the survival of pasteurized bone autografts compared with grafts without treatment? (3) Does the local application of zoledronate reduce the proportion of patients with fractures because of metaphyseal graft resorption? (4) Does local application of zoledronate improve union at the graft-host bone junction compared with untreated grafts?

METHODS

Between July 2011 and December 2019, we performed 538 musculoskeletal bone tumor resections. Of these, 101 patients underwent reconstruction with pasteurized bone autografts. Other reconstructions included tumor prostheses (150 patients), allografts (70 patients), reconstruction using a bone cement-plate construct (62 patients), and resection only (155 patients). We generally used pasteurized bone autograft when tumors showed an osteoblastic pattern, had less than one-third cortical destruction, and less than half of metaphyseal bone destruction. Six percent (6 of 101) were lost to follow-up, 6% (6 of 101) had incomplete clinical data, and 16% (16 of 101) had a follow-up period less than 2 years without an event, leaving 73 patients for evaluation. The median (interquartile range) age of the patients was 18 years (15 to 26). Ninety-seven percent (71 of 73) had a diagnosis of bone sarcoma. The median follow-up time was 46 months (33 to 75). From 2011 to 2014, 21 pasteurized bone autografts were prepared without local zoledronate, and from 2014 to 2019, 52 pasteurized bone autografts were prepared with local zoledronate because we thought it might improve union and reduce resorption of the graft. From our tumor registry database, we obtained age, sex, use of chemotherapy, graft length and location, pasteurized bone graft type, fixation methods, the use of local zoledronate, osteotomy gap, complications, proportion of grafts that united by 2 years, and local recurrences. Curves for graft survival were determined using the Kaplan-Meier method with the endpoint of autograft removal and metaphyseal fracture from graft resorption. The probabilities of graft removal were estimated by cumulative incidences using the competing risk analysis, where death was considered as the competing event. Intergroup differences in survival and multivariable analyses were performed using the log-rank test and a Cox regression analysis. A logistic regression model was used to evaluate the association between graft-host osseous union by 2 years and other baseline factors. Union was defined when a callus was seen to bridge the osteotomy line for at least three cortices in both the AP and mediolateral planes.

RESULTS

The 5-year survival rate of all 73 pasteurized grafts was 85% (95% confidence interval 74% to 92%). With the numbers available, we found no difference in the 5-year survival rates between grafts with and without local zoledronate (90% [95% CI 78% to 96%] versus 74% [95% CI 48% to 89%]; p = 0.30). Eleven percent (8 of 73) of patients had metaphyseal fractures because of graft resorption, primarily associated with osteoarticular grafts (5-year fracture-free survival 56% [95% CI 20 to 80]) rather than pasteurized graft-prosthesis composites (94% [95% CI 78% to 98%]) and intercalary grafts (91% [95% CI 50 to 99]; p = 0.001); there was no association with the use of local zoledronate (13%; 7 of 52) compared with those without local zoledronate (5%; 1 of 21) (odds ratio 3.1 [95% CI 0.4 to 27]; p = 0.43). Of the 84 graft-host bone junctions, 85% (71) of the grafts unified within 2 years, 7% (6) unified after 2 years, and 8% (7) of grafts showed nonunion. Union within 2 years was associated with fixation using plate compared with those with stem and with both stem and plate (odds ratio 6.6 [95% CI 1.4 to 31]; p = 0.02) and grafts treated with local zoledronate compared with those without treatment (OR 5.9 [95% CI 1.3 to 28]; p = 0.02).

CONCLUSION

The application of local zoledronate to pasteurized bone autografts for limb-sparing surgery improved the likelihood of graft union compared with untreated grafts, especially when the osteotomy junctions were fixed using plate osteosynthesis, but it did not appear to alter the proportion of patients who experience metaphyseal fracture of the grafts because of graft resorption. Although this is a small study, it suggests that the treatment of pasteurized bone autografts and perhaps bone allografts should be studied further to determine whether bisphosphonates or other adjuncts can improve the union time and return to function in patients undergoing bone tumor resections using these reconstruction types.

LEVEL OF EVIDENCE

Level III, therapeutic study.

Core Decompression with Local Administration of Zoledronate and Enriched Bone Marrow Mononuclear Cells for Treatment of Non-Traumatic Osteonecrosis of Femoral Head

Objective

To investigate the efficacy and safety of core decompression (CD) with local administration of zoledronate and enriched bone marrow mononuclear cells (BMMCS) for the treatment of non‐traumatic osteonecrosis of femoral head (ONFH).

Methods

A total of 17 patients (30 hips) diagnosed with stage II and III ONFH according to the 2019 revised Association for Research on Osseous Circulation (ARCO) staging criteria from 2012 to 2014 were retrospectively reviewed. The patients received the following therapy: the BMMCs and zoledronate were injected into the necrotic zone, respectively, along with CD. The mean age of the patients was 36.8 years; 14 were men and three were women. All patients included had non‐traumatic ONFH and a minimum follow‐up of 5 years, which ended when total hip arthroplasty (THA) was performed. Imaging modalities, including plain radiography, computed tomography (CT), and magnetic resonance imaging (MRI) were taken pre‐ and postoperatively. Harris hip score (HHS) was used to evaluate the functional outcomes of femoral head necrosis. Kaplan–Meier analysis was adopted to determine the probability of survivorship with THA as the end point in this series of patients. The correlation between radiological progression or THA and related risk factors were further analyzed. All complications were recorded.

Results

With THA as the follow‐up endpoint, All patients were followed up for an average of 69.1 ± 20.5 months (range, 18–95 months). Preoperative imaging found six hips (20%) at ARCO stage II, 14 hips (46.7%) at stage IIIA, 10 hips (33.3%) at stage IIIB. Fourteen hips (46.7%) shown progression radiologically, while six hips (20%) underwent TKA among these patients with hip preservation. The cumulative survival was 80% (95% CI, 0.608–905) at 5 years with THA as the end point. HHS improved from 63.3 ± 8.7 preoperatively to 74.6 ± 20.6 postoperatively (P = 0.000). Radiological progression was found to be associated with ARCO stage, Japanese Investigation Committee (JIC) type, and corticosteroid exposure (P = 0.047; P = 0.012; P = 0.031). However, no correlation was found between conversion to THA and the known risk factors. No major complication was reported, with only four patients complaining about general weakness and muscle soreness, and all disappeared within 2–3 days.

Conclusions

The novel treatment modality could relieve pain, delay the progression of collapse, which might be an effective and safe method for hip preservation of early and mid‐term ONFH. However, the effect of this method may be related to ARCO stage, JIC type, and corticosteroid exposure.

Augmentation of implant surfaces with BMP-2 in a revision setting : effects of local and systemic bisphosphonate

AIMS

We wanted to evaluate the effects of a bone anabolic agent (bone morphogenetic protein 2 (BMP-2)) on an anti-catabolic background (systemic or local zoledronate) on fixation of allografted revision implants.

METHODS

An established allografted revision protocol was implemented bilaterally into the stifle joints of 24 canines. At revision surgery, each animal received one BMP-2 (5 µg) functionalized implant, and one raw implant. One group (12 animals) received bone graft impregnated with zoledronate (0.005 mg/ml) before impaction. The other group (12 animals) received untreated bone graft and systemic zoledronate (0.1 mg/kg) ten and 20 days after revision surgery. Animals were observed for an additional four weeks before euthanasia.

RESULTS

No difference was detected on mechanical implant fixation (load to failure, stiffness, energy) between local or systemic zoledronate. Addition of BMP-2 had no effect on implant fixation. In the histomorphometric evaluation, implants with local zoledronate had more area of new bone on the implant surface (53%, p = 0.025) and higher volume of allograft (65%, p = 0.007), whereas implants in animals with systemic zoledronate had the highest volume of new bone (34%, p = 0.003). Systemic zoledronate with BMP-2 decreased volume of allograft by 47% (p = 0.017).

CONCLUSION

Local and systemic zoledronate treatment protects bone at different stages of maturity; local zoledronate protects the allograft from resorption and systemic zoledronate protects newly formed bone from resorption. BMP-2 in the dose evaluated with experimental revision implants was not beneficial, since it significantly increased allograft resorption without a significant compensating anabolic effect. Cite this article: Bone Joint Res 2021;10(8):488-497.

Locally administered bisphosphonate in hip stem revisions using the bone impaction grafting technique: a randomised, placebo-controlled study with DXA and five-year RSA follow-up

BACKGROUND:

Bisphosphonates have previously been shown to increase the density of impacted graft bone. In the present study we hypothesise that bisphosphonates also reduce early stem subsidence. We examined the effect of locally applied bisphosphonate to allografts on prosthetic micromotion and bone density in femoral stem revision with impaction grafting.

METHODS:

37 patients were randomised to either clodronate or saline as local adjunct to the morsellised allograft bone. 24 patients were finally analysed per protocol and evaluated by dual-energy x-ray absorptiometry (DXA) during the first year and with radiostereometric analysis (RSA) for 5 years.

RESULTS:

There were no significant differences neither in bone density, nor in migratory behaviour between the groups. The femoral stems had subsided 3.6 mm in both groups (p = 0.99) at 5 years and there was no difference as measured over time with mixed models analysis. The clinical outcome was good in both groups.

CONCLUSION:

Clodronate as a local addendum to allograft bone in hip revision did not increase bone density or reduce micromotion of the implant.

Topical zoledronic acid decreases micromotion induced bone resorption in a sheep arthroplasty model

Background

Initial micromotion of a total hip replacement is associated with aseptic loosening. The use of bisphosphonates could be one way to reduce peri-implant bone resorption induced by micromotion. Bisphosphonates compounds are inhibitors of bone resorption. The aim of this study was to investigate whether local treatment with bisphosphonate would reduce bone resorption and fibrous tissue around an experimental implant subjected to micromotion.

Methods

One micromotion implant were inserted into each medial femoral condyle in ten sheep. During each gait cycle the implant axially piston 0.5 mm. During surgery one of the femoral condyles were locally treated with 0.8 mg zoledronate. The other condyle served as control. Observation period was 12 weeks.

Results

Histological evaluation showed a fibrous capsule around both the control and bisphosphonate implants. Histomorphometrical analysis showed that 97% of the surface on both control and bisphosphonate implants were covered by fibrous tissue. However, the bisphosphonate was able to preserve bone in a 1 mm zone around the implants.

Conclusion

This study indicates that local treatment with bisphosphonate cannot prevent the formation of a fibrous capsule around an implant subjected to micromotion, but bisphosphonate is able to reduce resorption of peri-prosthetic bone.

Local Administration of Bisphosphonate-soaked Hydroxyapatite for the Treatment of Osteonecrosis of the Femoral Head in Rabbit

Background:

Systemic administration of bisphosphonates has shown promising results in the treatment of osteonecrosis of the femoral head (ONFH). However, few studies have evaluated the efficacy of local zoledronate (ZOL) administration in the treatment of ONFH. The purpose of this study was to investigate whether local administration of bisphosphonate-soaked hydroxyapatite (HA) could improve bone healing in an experimental rabbit model of ONFH.

Methods:

This experimental study was conducted between October 2014 and June 2015. Forty-five rabbits underwent simulated ONFH surgery. Immediately following surgery, they were divided into three groups: model (untreated, n = 15), HA (treated with HA alone, n = 15), and HA + ZOL (treated with HA soaked in a low-dose ZOL solution, n = 15). Histological, immunohistochemical, and quantitative analyses were performed to evaluate bone formation and resorption 2, 4, and 8 weeks after surgery.

Results:

Gross bone matrix and hematopoietic tissue formation were observed in the HA + ZOL group 4 weeks after surgery. The immunohistochemical staining intensities for 5-bromodeoxyuridine, runt-related transcription factor 2, osteocalcin, osteopontin, and osteoprotegerin were significantly higher in the HA + ZOL group than that in the model (P < 0.001, P < 0.001, P < 0.001, P < 0.001, and P = 0.018, respectively) and HA groups (P = 0.003, P = 0.049, P < 0.001, P = 0.020, and P = 0.019, respectively), whereas receptor activator of the nuclear factor-κB ligand staining intensity was significantly lower in the HA + ZOL group than that in the model and HA groups (P = 0.029 and P = 0.015, respectively) 4 weeks after surgery. No significant differences in bone formation or bone resorption marker expression were found between the three groups 2 or 8 weeks after surgery (P > 0.05).

Conclusions:

Local administration of HA soaked in a low-dose ZOL solution increased new bone formation while inhibiting bone resorption in an animal model of ONFH, which might provide new evidence for joint-preserving surgery in the treatment of ONFH.

Bisphosphonate Use and Risk of Implant Revision after Total Hip/Knee Arthroplasty: A Meta-Analysis of Observational Studies

Objective

Several studies investigated the association between bisphosphonate use and the risk of implant revision after total hip or knee arthroplasty (THA or TKA); However, the findings were inconsistent. We performed this meta-analysis to evaluate the overall relative risk of such an event.

Methods

We searched the PubMed, EMBASE and Cochrane library databases to identify relevant publications on April 22, 2015. To calculate the pooled risk ratios (RRs) with 95% confidential intervals (CIs), a fixed- or random-effects model was applied based on the heterogeneity across studies.

Results

Three cohort studies and one case-control study were included in this meta-analysis. Compared with the bisphosphonate nonusers, the patients who used bisphosphonates for a long period of time had a significantly decreased risk of implant revision after THA/TKA (summary adjusted RR = 0.48, 95% CI: 0.38–0.61), and the summary adjusted RRs for the users who underwent THA and those who underwent TKA were 0.47 (95% CI: 0.36–0.61) and 0.45 (95% CI: 0.21–0.95), respectively.

Conclusions

Long-term use of bisphosphonates is correlated with a significantly decreased risk of implant revision after THA/TKA. However, due to limited number of the included studies, the findings of the present study should be treated with caution. More well-designed studies are required to further confirm our findings.