Bisphosphonate delivery to tubular bone allografts

Does intramedullary nailing improve the union rate or decrease mechanical complications for patients with extremity sarcoma after biological reconstruction?

INTRODUCTION

This is a retrospective study that evaluate the outcome of patients with extremity sarcoma between extramedullary plate and intramedullary nailing for the biological reconstruction after tumor resection.

METHODS

58 patients (40 treated with plate fixation and 18 with intramedullary nailing, IM group) with sarcomas of the lower and upper extremity who received biological reconstruction at our bone tumor center from November 2003 to November 2015 were reviewed for the study. There were 29 male and 29 female patients with a mean age of 20.8 years (range, 5-72 years). The mean follow-up duration was 90.8 months (range, 12.2-244.4 months). All data were obtained from the clinical, radiograph records and follow-up information. The analysis of outcome, survival, local recurrence, function and complications of patients in the plate group and IM group was performed.

RESULTS

28 cases in the plate group lived at the last follow-up, of which 26 had no evidence of disease, 2 lived with the pulmonary metastasis, whereas 15 in the IM group lived at the last follow-up, of which all had no evidence of disease and no lived with the pulmonary metastasis. There was no significant difference between the two groups for the prognosis. Meanwhile, there was no significant difference of incidence of nonunion, graft fracture and fixation breakage between the two groups, whereas the time to diaphysis union in the plate group (11.6 ± 2.7 months) was shorter than that in IM group (14.7 ± 4.8 months, P = 0.015). It had the tendency that the time to mechanical complications in the intramedullary nailing group (38.1 ± 39.6 months) was longer than that in the plate group (15.7 ± 13.4 months, P = 0.058,95% CI,-45.6-0.8). Furthermore, the infection occurred in 12 cases and five grafts of them developed the deep infection and the mean time to deep infection was 14.8 ± 20.5 months. Furthermore, the incidence of local recurrence for the patients who had plate fixation was similar to the incidence of patients who had nailing fixation. At the last follow-up, the functional evaluation was performed for 39 patients. There was no significant difference in MSTS and VAS functional score for patients between in the plate group (n = 32) and IM group (n = 7).

CONCLUSIONS

The findings of the present study showed that intramedullary nailing does not improve the union rate or decrease the incidence of mechanical complications for patients with extremity sarcoma after biological reconstruction. However, intramedullary nailing may have potential advantages on the service life for the biological reconstruction after extremity sarcoma resection.

Use of Magnetic Growing Intramedullary Nails in Compression During Intercalary Allograft Reconstruction

Traditionally, intercalary allograft reconstruction after tumor resection has had a high rate of complications, particularly nonunion. Plate and intramedullary nail fixation have been used alone and in combination to improve union rates. This study sought to evaluate a new technique that uses a magnetic growing intramedullary nail to compress the osteotomy sites to aid in healing and to answer 2 questions: (1) What is the union rate and the time to union when using magnetic growing intramedullary nails? (2) What complications occur with this technique? Eight patients with 15 osteotomy sites with a minimum follow-up of 14 months were retrospectively reviewed. Seven of the 8 patients underwent initial reconstruction with the magnetic nail, whereas 1 patient underwent treatment of a nonunion that occurred with prior carbon fiber nail fixation. Twelve of the 15 osteotomy sites had healed by an average of 9 months. Nonunions occurred in 2 patients with an associated failure of the hardware. One of these patients healed after revision surgery. Of the patients who healed at both sites, 1 had a fracture through the allograft, 1 had backing out of a locking screw that required removal, and 1 required a manipulation under anesthesia of the knee. Two patients underwent successful limb lengthening needed because of an expected limb-length discrepancy after healing occurred. Use of growing intramedullary nails in compression mode led to an 87% union rate at final follow-up with acceptable complications. This technique provides a viable alternative to standard nail and plate fixation when intercalary allografts are used. [Orthopedics. 2018; 41(6):330-335.].

Antimicrobial distribution from local delivery depends on dose : a pilot study with MRI

BACKGROUND

Tissue distribution after local delivery has been quantified over a period of 5 hours on 7-T MRI in a rabbit model using gadolinium-labeled diethylenetriamine pentaacetic acid (Gd-DTPA) as an antimicrobial surrogate; however, it is unknown how the Gd-DTPA load in a local depot will affect the duration of high-concentration Gd-DTPA in local tissues after surgical débridement.

QUESTIONS/PURPOSES

We determined whether the Gd-DTPA load in bone cement affected its local tissue distribution over a period of 1 month after local delivery.

METHODS

A 1-cm3 soft tissue dead space was created in the quadriceps of seven rabbits and filled with gadolinium-loaded bone cement. At 7, 14, and 33 days, the volume of tissue with a Gd-DTPA concentration of more than 14 μg/mL was calculated from T1-weighted images using 7-T MRI. Differences in volumes of distribution were analyzed with ANOVA.

RESULTS

The volume of tissue with more than 14 μg/mL Gd-DTPA was much larger from higher gadolinium loads on Day 7 (p=0.02) (2121 mm3 for 10 g and 665 mm3 for 1 g) and smaller with time for the 10-g formulation (2121 mm3 on Day 7 and 1241 mm3 on Day 14).

CONCLUSIONS

Volume of distribution and duration of Gd-DTPA after local delivery increased with increasing load in the cement and decreased with time.

CLINICAL RELEVANCE

For local delivery, high antimicrobial concentrations would be expected in greater volumes of tissue, for longer durations, when higher antimicrobial loads are used.

Distribution of locally delivered antimicrobials is limited by cortical bone: a pilot study

BACKGROUND

Local delivery is required to achieve the high antimicrobial concentrations needed to treat biofilm-forming infections. The delivery site is commonly either in the intramedullary canal or at the periosteal surface. It is unknown whether locally delivered antimicrobials are transported transcortically between the endosteal and periosteal surfaces when the infection involves the opposite surface.

QUESTIONS/PURPOSES

(1) Are antimicrobials transported transcortically between the endosteal and periosteal surfaces over time? And (2) are transcortical antimicrobials transported uniformly over the cortical surface?

METHODS

To study transcortical antimicrobial transport, 12 human cadaveric femoral segments obtained from two women aged 63 and 64 years and one man aged 64 years were filled with antimicrobials. Three diaphyseal segments were filled with 5 wt% vancomycin in an N-isopropylacrylamide-based hydrogel and eluted in phosphate-buffered saline under infinite-sink conditions for 5 days; vancomycin was assayed by high-performance liquid chromatography. Nine segments (three infraisthmal diaphysis, three metaphysis, three epiphysis) embedded in 0.1% agarose gel were filled with aqueous doxycycline (400 μg/mL) and imaged under ultraviolet light for fluorescence on the periosteal surface at 15-minute intervals for 3 days.

RESULTS

Transcortical vancomycin elution occurred: 8.65 mg during Day 1 and 26.5 mg by Day 5. Fluorescence from transcortical doxycycline transport was only visualized at focal locations corresponding to vascular foramina, appearing first at 5 to 10 minutes, with none over the majority of the periosteal surface for up to 24 hours.

CONCLUSIONS

Transcortical transport of locally delivered antimicrobials occurs primarily through vascular foramina.

CLINICAL RELEVANCE

Transcortical antimicrobial transported may not be adequate to achieve therapeutic levels for infection on the far side of an intact cortex.

Effect of low-level laser therapy on incorporation of block allografts

OBJECTIVE

To assess the effect of low-level laser therapy (LLLT) on the incorporation of deep-frozen block allografts in a rabbit model.

BACKGROUND DATA

Studies have shown that LLLT has beneficial effects on tissue repair and new bone formation.

METHODS

Bone tissue was harvested from two rabbits, processed by deep-freezing and grafted into the calvaria of 12 animals, which were then randomly allocated into two groups: experimental (L) and control (C). Rabbits in group L were irradiated with an aluminum gallium arsenide diode laser (AlGaAs; wavelength 830 nm, 4 J/cm(2)), applied to four sites on the calvaria, for a total dose of 16 J/cm(2) per session. The total treatment dose after eight sessions was 128 J/cm(2). Animals were euthanized at 35 (n = 6) or 70 days (n = 6) postoperatively.

RESULTS

Deep-freeze-processed block allografts followed by LLLT showed incorporation at the graft-host interface, moderate bone remodeling, partial filling of osteocyte lacunae, less inflammatory infiltrate in the early postoperative period, and higher collagen deposition than the control group.

CONCLUSION

Optical microscopy and scanning electron microscopy showed that allograft bone processed by deep-freezing plus LLLT is suitable as an alternative for the treatment of bone defects. Use of the deep-freezing method for processing of bone grafts preserves the structural and osteoconductive characteristics of bone tissue.

Effects of the systemic administration of alendronate on bone formation in a porous hydroxyapatite/collagen composite and resorption by osteoclasts in a bone defect model in rabbits

Several bisphosphonates are now available for the treatment of osteoporosis. Porous hydroxyapatite/collagen (HA/Col) composite is an osteoconductive bone substitute which is resorbed by osteoclasts. The effects of the bisphosphonate alendronate on the formation of bone in porous HA/Col and its resorption by osteoclasts were evaluated using a rabbit model. Porous HA/Col cylinders measuring 6 mm in diameter and 8 mm in length, with a pore size of 100 μm to 500 μm and 95% porosity, were inserted into a defect produced in the lateral femoral condyles of 72 rabbits. The rabbits were divided into four groups based on the protocol of alendronate administration: the control group did not receive any alendronate, the pre group had alendronate treatment for three weeks prior to the implantation of the HA/Col, the post group had alendronate treatment following implantation until euthanasia, and the pre+post group had continuous alendronate treatment from three weeks prior to surgery until euthanasia. All rabbits were injected intravenously with either saline or alendronate (7.5 μg/kg) once a week. Each group had 18 rabbits, six in each group being killed at three, six and 12 weeks post-operatively. Alendronate administration suppressed the resorption of the implants. Additionally, the mineral densities of newly formed bone in the alendronate-treated groups were lower than those in the control group at 12 weeks post-operatively. Interestingly, the number of osteoclasts attached to the implant correlated with the extent of bone formation at three weeks. In conclusion, the systemic administration of alendronate in our rabbit model at a dose-for-weight equivalent to the clinical dose used in the treatment of osteoporosis in Japan affected the mineral density and remodelling of bone tissue in implanted porous HA/Col composites.

Intercalary allograft reconstructions using a compressible intramedullary nail: a preliminary report

BACKGROUND

Although intercalary allograft reconstructions are commonly performed using intramedullary devices, they cannot generate compression across host-allograft junctions. Therefore, they sometimes are associated with gap formation and suboptimal healing conditions.

QUESTIONS/PURPOSES

We describe a new technique and present preliminary results for intercalary allograft reconstructions for tumors using a compressible intramedullary nail.

PATIENTS AND METHODS

We retrospectively reviewed 10 patients (19 host-allograft junctions) who underwent intercalary allograft reconstruction using the compression nailing technique. Two patients were excluded as they had additional vascularized fibular autografts, leaving 15 junctions in eight patients for analysis. Three of the intercalary reconstructions had supplemental plate fixation at one junction. All patients received host bone reamings and cancellous allograft and one had bone marrow aspirate and demineralized bone matrix in addition to the cancellous allograft. The minimum followup was 3 months (mean, 18 months; range, 3-39 months).

RESULTS

Thirteen of 15 junctions healed without additional surgery. Two diaphyseal-diaphyseal junctions did not unite after allograft arthrodeses. One patient underwent revision for nonunion 8 months after the initial procedure, with subsequent healing. The second patient had no evidence of union at 6 months, after which he was lost to followup. There were no allograft fractures or infections in any reconstruction. One patient died of metastatic renal cell carcinoma, and one patient had multicentric local soft tissue recurrences of a periosteal osteosarcoma requiring resection.

CONCLUSIONS

Our early observations indicate newer compressible intramedullary nails reliably address junctional gap formation, providing for a high rate of union while retaining the long-term benefits of intramedullary stabilization.

LEVEL OF EVIDENCE

Level IV, case series. See Guidelines for Authors for a complete description of levels of evidence.