Gentamycin-impregnated calcium phosphate cement for calcaneal osteomyelitis: a case report

Gentamicin-permeated cement to sustain mechanical support for the treatment of a chronic calcaneal abscess. A case report

INTRODUCTION AND IMPORTANCE

Chronic calcaneal osteomyelitis is a challenging condition associated with high relapse rates, requiring a multidisciplinary approach and various therapeutic options for effective management. We report a very rare case of a pyogenic osteomyelitis of the os calcis presented as a bone abscess.

CASE PRESENTATION

A diabetic male patient presented with chronic osteomyelitis of the calcaneus in the form of bone abscess with a cavity of 6*5 cm. After pus evacuation and debridement of the cavity, gentamycin-impregnated polymethylmethacrylate cement was used to locally assist in controlling the infection and to assure mechanical support. Antibiogram-based oral antibiotic was administrated for 6 weeks. At final follow-up, the patient could walk without any assistance and was able to raise his body on the operated heel, with no signs of infection.

CLINICAL DISCUSSION

This case illustrates successful conservative surgical treatment of calcaneal abscess using antibiotic-impregnated cement for mechanical support and local infection control.

CONCLUSION

Incorporating antibiotic-impregnated cement into conservative foot surgeries for deeply embedded calcaneal abscesses provides effective infection control, mechanical support, and functional preservation, leading to successful treatment outcomes.

Diabetic Pedal Osteomyelitis and Its Treatment

Diabetes is a fast-growing chronic metabolic disorder that is widely associated with foot ulcers. The major challenge among these ulcers is wound infections, altered inflammatory responses, and a lack of angiogenesis that can complicate limb amputation. The foot, because of its architecture, becomes the part most prone to complications and the infection rate is higher mainly between the toes due to the humid nature. Therefore, the infection rate is significantly higher. Wound healing in diabetes is a dynamic process usually delayed due to poor immune function. Diabetes-related pedal neuropathy and perfusion disturbances can lead to a loss of sensation in the foot. This neuropathy can further be a risk factor for ulcer development due to repetitive mechanical stress that later might get infected by the invasion of microorganisms extending to the bone and causing an infection called pedal osteomyelitis. This review details the pathophysiology, the biomaterials aiding in the infection cure and regeneration of bone along with their limitations, as well as their future prospects.

Long-term antibacterial activity of vancomycin from calcium phosphate cement in vivo

BACKGROUND

Periprosthetic joint infection is a major complication of total joint arthroplasty, with treatment requiring a two-stage exchange procedure and 6 weeks of systemic antibiotics. However, depending on the infection site, intravenous delivery of antibiotics like vancomycin (VCM) can have poor tissue transferability, thus reducing their therapeutic effect.

OBJECTIVE

This study demonstrates the 24-week in vivo release profile and antibacterial activity of VCM from calcium phosphate cement impregnated with VCM (CPC/VCM) and compares them with those from polymethylmethacrylate impregnated with VCM (PMMA/VCM).

METHODS

Rats were implanted with the test specimens between the fascia and quadriceps. After implantation for 24 weeks, the test specimens were removed and residual VCM was extracted to calculate the concentration of VCM released into rat tissues. We also examined the antibacterial activity of releasable VCM from the removed test specimens by placing them directly onto the surface of agar.

RESULTS

CPC/VCM released greater concentrations of VCM for a longer period of time within the 24 weeks than PMMA/VCM. Moreover, CPC/VCM released 1.4 to 26.1-fold more VCM than PMMA/VCM. Using Staphylococcus aureus, antibacterial activity was logarithmically correlated with VCM concentration across the entire concentration range tested (12.5-800 μg/mL). While the area within which inhibition was observed-the inhibition zone-for both CPC/VCM and PMMA/VCM formed and gradually shrank with time after implantation, that for CPC/VCM was significantly larger than that for PMMA/VCM in each week after implantation.

CONCLUSION

CPC/VCM releases greater amounts of VCM with antibacterial activity for longer periods of time than PMMA/VCM, suggesting that CPC is effective for facilitating the release of antibiotics for local action in patients with established postoperative infection.

Extensive eggshell-like debridement technique plus antibiotic-loaded calcium sulphate for one-stage treatment of chronic calcaneal osteomyelitis

BACKGROUND

Management of chronic calcaneal osteomyelitis is challenging. At present, there is still no widely accepted, simple, and effective surgical method to eradicate the infection and prevent osteomyelitis recurrence. The objective of this study was to assess the outcomes of one-stage treatment of chronic calcaneal osteomyelitis with a shape-preserving debridement technique combined with antibiotic-loaded calcium sulphate.

METHODS

Between 2012 and 2018, 33 patients (33 limbs) with chronic calcaneal osteomyelitis were treated with a novel debridement technique, named "eggshell-like debridement", plus antibiotic-impregnated calcium sulphate. The infection remission rate, recurrence rate, and amputation rate were analyzed. The American Orthopedic Foot and Ankle Society (AOFAS) ankle and hindfoot score was used to assess postoperative hindfoot function.

RESULTS

26 patients (81.8%) achieved infection remission without recurrence. In the patients with osteomyelitis remission, pain, limitation of movement, sinus tracts, and typical redness and swelling were generally eliminated. Most of the patients could tolerate full weight-bearing without pain. The average AOFAS ankle and hindfoot score was 88 points (range, 67-100 points), implying the foot function was mostly restored. 6 patients (18.2%) had osteomyelitis recurrence but no amputation was required to elimilate the infection.

CONCLUSIONS

Eggshell-like debridement combined with antibiotic-loaded calcium sulphate is an effective method for one-stage management of chronic calcaneal osteomyelitis. With the application of this technique, secondary autogenous bone or muscle flap grafts are unnecessary. The surgical procedure can be simplified whlie the hindfoot function is well preserved.

In Vivo Release of Vancomycin from Calcium Phosphate Cement

Calcium phosphate cement (CPC) has good release efficiency and has therefore been used as a drug delivery system for postoperative infection. The release profile of CPC has mainly been evaluated by in vitro studies, which are carried out by immersing test specimens in a relatively large amount of solvent. However, it remains unclear whether antibiotic-impregnated CPC has sufficient clinical effects and release in vivo. We examined the in vivo release profile of CPC impregnated with vancomycin (VCM) and compared this with that of polymethylmethacrylate (PMMA) cement. To evaluate the release profile in vitro, the test specimens were immersed in 10 mL sterile phosphate-buffered saline per gram of test specimen and incubated at 37°C for 56 days in triplicate. For in vivo experiments, the test specimens were implanted between the fascia and muscle of the femur of rats. Residual VCM was extracted from the removed test specimens to determine the amount of VCM released into rat tissues. CPC released more VCM over a longer duration than PMMA in vitro. Released levels of VCM from CPC/VCM in vivo were 3.4-fold, 5.0-fold, and 8.6-fold greater on days 1, 7, and 28, respectively, than those released on the corresponding days from PMMA/VCM and were drastically greater on day 56 due to inefficient release from PMMA/VCM. The amount of VCM released from CPC and PMMA was much higher than the minimum inhibitory concentration (1.56 μg) and lower than the detection limit, respectively. Our findings suggest that CPC is a suitable material for releasing antibiotics for local action against established postoperative infection.