After surgical debridement and antibiotic-loaded calcium sulfate implantation, most of patients received satisfying results. 94.7% (18/19) cases achieved infection remission after first surgical treatment, while only 1 case received secondary treatment for infection recurrence. Undoubtedly, the high remission rate should be attributed to the radical debridement and the use of local antibiotics delivery system, which removed the infected tissues in a more thorough way and eliminated the residual organisms by a longer therapeutic duration. This remarkable result was similar to the previous report. In their study, N. Kanakaris et al used intramedullary removal, intramedullary debridement with reamer-irrigator-aspirator (RIA) device and antibiotic-loaded cement rods in the treatment of 24 such patients. The cement rods were removed once the infections were well controlled. With a mean follow-up of 21 months, 23 (96%) patients had no evidence of recurrent infection. The difference of their study lies in the application of RIA device and antibiotic cement. The RIA system is a device that was initially developed to prevent fat embolism and lessen the systemic inflammatory process after reaming the femur in nailing procedures[15, 16]. Due to its versatility, it has been expanded to the treatment of long bone osteomyelitis[17, 18]. However, RIA system is not introduced into our country by now, yet the methods we used were similar to RIA system, and with a pretty good outcome as we demonstrated. Antibiotic cement was non-absorbable, requiring a secondary removal intervention, or its long existence might lead to infection recurrence. It is one of the conspicuous shortcomings compared to calcium sulfate in our study.
This study also included nine cases with fracture non-union. They were treated by intramedullary nails removal, segmental bone resection, medullary canal reaming and irrigation, delivery of local antibiotic and secondary bone transport. All of patients received infection remission and length restorage of involved limbs. Although the results were satisfying, the best protocol on the management of infected non-union is still controversial. Those who prefer to retain the nails believe that fracture healing is more important, management of intramedullary infection could be postponed until bone healing, yet those who are more radical recommend that removal of intramedullary nails will take infection control in prior consideration. Based on different concepts, the treatment methods are various, which include: 1). Local debridement and antibiotics usage but retaining the nail, 2). Current nail removal, re-reaming and replacement of a larger diameter intramedullary nail or a resorbable antibiotic coating one, 3). Nail removal, segmental bone resection, re-reaming, local antibiotics delivery and bone reconstruction. To our opinion, management with infection is more important than bone healing, since incomplete debridement and internal fixation are unsuitable for infection disease. Persistent infection or infection recurrence, however, might prevent the healing process and even lead to diffused osteomyelitis, disability and even amputation. We are inclined to the third protocol mentioned above, and has been well proved by results.
Local antibiotic-carriers were proposed in 1970s[19, 20], and has been recommended as a bone substitute in the management of bone defect, or as a local antibiotic carrier in bone infection. Calcium sulfate as one of the local applied carriers was approved by the US FDA in 1996 with osteoconductivity for non-diabetic patients, and now has been practically long applied in orthopedic surgery, including as an antibiotic carrier, filling bone defects, expanding solvent for bone graft[21–23]. As an absorbable carrier, it has stable curve of releasing antibiotics and maintain about 6–8 weeks higher than MIC. The local concentration is about 100–1000 times higher than the serum levels resulting from intravenous treatment. It is sufficiently high to penetrate biofilm and eliminate the stubborn bacteria. Furthermore, calcium sulfate exhibits similar microstructure to cancellous bone. After being absorbed in situ, the network structure is left, and the presence of trabecular bone can be observed under the light microscope, which contributes to the crawling and growing of blood vessels and bone cells[25, 26]. Calcium sulfates applied in clinical practice are mostly injectable, and they are very suitable for filling the marrow canal.
Prolonged aseptic drainage was the most frequent recorded complication in our study, with a relatively high rate of 36.8% (7/19). The drainage rate was similar to the previous studies, in which the drainage rate ranged from 4.2–33%[27–29]. To our experience, poor soft tissue coverage, scar formation and excessive calcium sulfate implantation may be the reasons for the high incidence of postoperative exudation. Although this kind of aseptic exudation is not a sign of infection, management of this postoperative drainage is of great necessity, or a soggy gauze is prone to cause wound infection. Generally, routine treatment of prolonged drainage includes regular dressing and wound care. Other effective methods to prevent prolonged aseptic drainage may include good soft tissue coverage and reduction of calcium sulfate implantation.
The weakness of our study is still obvious. Firstly, our outcomes were not compared with those of other surgical methods. In addition, our study included multiple situations, such as different location of infection and different surgical treatment on unhealed and healed bone, which inevitably leaded to the outcomes more complex. However, we have to point out that the emphasis of our study was to introduce an effective method to eliminate the infection after intramedullary nailing (not focusing on the management of nonunion only), and all cases received the same management methods of infection, so we think the study is still meaningful.