Osteomyelitis is a common and severe orthopedic complication, characterized by inflammation within the bone and/or bone marrow, and encompasses both chronic and acute forms. It is straightforward to diagnose but complex to treat, remaining one of the challenges in orthopedic management [1]. Osteomyelitis can be further classified into hematogenous, traumatic, and diabetic foot osteomyelitis based on different etiological factors [2]. While the pathogenesis of osteomyelitis theoretically includes both infectious and non-infectious factors, most cases are caused by bacterial infections, with non-bacterial osteomyelitis predominantly seen in children and adolescents [3]. Clinically, approximately 10% to 30% of patients with acute osteomyelitis progress to chronic osteomyelitis [4]. This progression is often due to bacteria forming a biofilm at the infection site, which antibiotics cannot completely eradicate, leading to recurrent episodes and ultimately chronic osteomyelitis [5]. Traditional treatment methods for osteomyelitis include thorough debridement, anti-infective treatment, and bone cement filling [1][6][7]. However, in special cases, such as patients with refractory wounds or sinus tracts, these traditional treatments may not yield satisfactory outcomes. Live Leech Therapy (LLT), supported by emerging scientific evidence for its anti-inflammatory, anticoagulant, and vasodilatory properties mediated by bioactive salivary components (e.g., hirudin, hyaluronidase, bdellins, eglin) [8], has shown promise in promoting wound healing and microcirculation in conditions like venous congestion and selected inflammatory/infectious conditions. However, its application in chronic osteomyelitis remains understudied. Here, we present a rare case of chronic ischial osteomyelitis with a persistent unhealed sinus tract that was successfully treated using LLT in combination with antimicrobial drug treatment.

Based on the patient’s clinical manifestations, physical signs, imaging examinations, comprehensive laboratory microbial culture, and postoperative bone tissue pathological examination (Figure 2), the final diagnosis was chronic ischial osteomyelitis with a sinus tract.

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Figure 1.(A)-(C): Coronal, axial, and sagittal views (in this order) of pelvic CT in 2023. (D)-(F): Coronal, axial, and sagittal views (in this order) of the admission pelvic CT scan, compared to the 2023 CT. The arrow indicates nodular and patchy densities in the ischial tuberosity and inferior pubic ramus, with surrounding soft tissue swelling and gas, suggesting possible sinus tract formation (▲). (G)-(H): Coronal and axial views (in this order) of pelvic T2-weighted MRI in 2023. (I)-(J): The admission pelvic T2-weighted MRI. (K)-(L): Coronal and axial views (in this order) of the 2-month post-discharge pelvic MRI. Arrow shows ischial tuberosity edema and extensive perianal soft tissue edema. Right ischial tuberosity bone marrow edema was substantially mitigated, and soft tissue swelling significantly alleviated (▲).

On the fifth day of admission, the patient underwent excisional debridement of the ischial ulcer wound, vacuum sealing drainage (VSD) with negative pressure suction, and pathological biopsy, and was administered ceftazidime (2 g intravenously every 12 hours) for anti-infective treatment. On the eighth day post-operation, the VSD drainage tube was removed, and daily cleaning and dressing changes were initiated. Two weeks post-operation, the surgical incision and the ischial sinus tract opening of the patient remained open, with light yellow purulent secretion still exuding.

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Figure 2.(A): Right buttock sinus tract and peripheral scar tissue during the operation. (B): Histological examination (hematoxylin and eosin staining, 100 × under microscope) reveals granulation tissue from the right buttock sinus tract lesion, with myxoid change and fibrinoid surface necrosis.

Given the patient’s long-term medical history, along with the presence of persistent wound exudate two weeks after surgery and scant granulation tissue within the sinus tract considering the refractory nature of chronic osteomyelitis wounds, we assessed the wound condition, past medical history (particularly allergy history), and the patient’s tolerance, and subsequently attempted LLT for treatment. Artificially cultivated medical leeches (Hirudo nipponica Whitman) sourced from Guangxi Kekang Technology Group Co., Ltd. were used. These leeches were bred in strict accordance with relevant requirements, underwent a series of purification processes, and were certified free of pathogenic bacteria by a qualified third-party testing institution. Following the operational specifications of Zhuang medicine leech therapy [9], the specific procedure was as follows: Based on the condition of the patient’s wound, five leeches were applied via their oral suckers to two wound sites on the patient’s right buttock (the sinus tract opening and the anal fistula site), the leeches adhered only to the surface of the sinus tract opening and did not penetrate into the tract lumen. The leeches were allowed to feed until natural detachment occurred (typically around 0.5 hours). If leeches failed to detach within one hour, a cotton swab moistened with 75% ethanol was gently applied to the leeches’ mouthparts from a distance of 0.5 cm to encourage detachment. After leech detachment, the next step was to irrigate the treatment area with normal saline three times and then disinfected with iodophor. Once hemostasis at the suction site was confirmed, the area was covered with sterile gauze and dressed. Post-treatment, leeches were counted, euthanized by submersion in 75% ethanol, and disposed of as medical waste. Leech therapy was administered twice weekly, in conjunction with ongoing anti-infective management (ceftazidime, 2g intravenously every 12 hours). The patient continued oral cefixime tablets (0.1g, twice a day) for one-week post-discharge.

The exudate from the sinus tract was significantly reduced on the day of leech treatment. The patient experienced no discomfort during or after the treatment. As treatment progressed, the exudate from the sinus tract opening gradually disappeared, new granulation tissue formed, and the wound healed. On the 14th day post-treatment, the sinus tract opening and surgical wound of the patient were essentially healed, with no exudate. The CRP and ESR level returned to normal before discharge. At the two-month and six- month post-discharge follow-up, the perianal sinus tract opening was completely closed, with no bleeding or exudation from the wound (Figure 3), the follow-up pelvic MRI two months after discharge indicated that the bone marrow edema in the right ischial tuberosity was substantially mitigated and the soft tissue swelling was significantly alleviated; anal crypt depression also significantly improved on anoscopy compared to 2023, indicating remission of the anal fistula (Figure 4).

In this study, we report a rare case of chronic ischial osteomyelitis successfully treated with Live Leech Therapy, a novel, yet underutilized, therapeutic modality.

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Figure 3.(A): Buttock appearance at admission. (B): Buttock appearance 2 weeks post-debridement. (C): Leech therapy process. (D): Buttock appearance one week after leech therapy. (E): Buttock appearance at discharge 2 weeks after leech therapy. (F): Buttock appearance 2 months post-discharge. (G): Buttock appearance 6 months post-discharge.

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Figure 4.(A): Arrow indicates prominent crypt depression at 7 o’clock, suggestive of sinus tract formation (in 2023). (B): Reduced crypt depression, 2 months post-discharge.

After unsuccessful attempts with radical debridement and antibiotic therapy, we utilized Live Leech Therapy to eliminate infected soft tissue, stimulate granulation tissue formation, and ultimately achieve closure of the patient’s sinus tract. Osteomyelitis is classified based on duration as acute or chronic osteomyelitis, further subdivided into chronic primary and chronic secondary osteomyelitis [10]. However, the clinical significance of this classification is debatable, as the time-based definitions of acute and chronic osteomyelitis lack strict and precise criteria. Chronic osteomyelitis is generally defined as persistent infection lasting several months to years. However, treatment strategies do not demonstrably differ based on duration. Thus, the presence of dead bone, rather than the length of the disease process, is more critical in determining treatment plans [11]. Chronic osteomyelitis is more commonly observed in the metaphyses of long bones, but less so in the pelvis. In pediatric patients, the infection often originates in the superior acetabular region, due to the rich blood supply, then gradually spreads to the iliac, pubic, and ischial bones. In adults, however, osseous maturation of the acetabulum leads to more frequent involvement of the iliac crest, pubic, and ischial bones [12]. The diagnosis of chronic osteomyelitis typically relies on a combination of clinical, laboratory, and imaging findings. These may include elevated white blood cell counts, ESR, CRP levels, and positive bacterial cultures, as well as CT and MRI. A prior surgical history also contributes to the diagnosis. Common clinical manifestations include localized pain, erythema, and sinus tract formation, while fever is relatively uncommon [13]. Although laboratory tests, such as elevated ESR and CRP, can aid in the diagnosis, their limited specificity, coupled with non-specific early clinical and imaging features, often leads to delayed or missed diagnoses [14]. Treatment strategies for chronic osteomyelitis, regardless of the affected bone, are generally consistent. Systemic antibiotic therapy is the primary approach. If dead bone is present, surgical debridement is necessary.

Chronic osteomyelitis is characterized by a complex and variable spectrum of pathogens, often exhibiting mixed, polymicrobial, and cross-infections, which are identifiable through laboratory testing and pathological biopsies. While traditionally, Gram-positive bacteria (e.g., Staphylococcus aureus, Enterococcus spp.) were considered predominant [5][15], recent years have seen a significant rise in Gram-negative bacteria (GNB), especially in developing countries. In Middle East conflict-related osteomyelitis, GNB detection even surpasses Gram-positive bacteria, despite the latter often causing more severe infections [16]. Notably, GNB detection can reach 51.5% in some parts of Egypt [17], and studies in China show GNB as the sole causative microorganism in infectious bone diseases more often than Gram-positive bacteria [18]. Commonly implicated GNB in osteomyelitis include Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae, Acinetobacter baumannii, and Enterobacter spp. [19][20]. Though Proteus mirabilis osteomyelitis is rare, most cases link to enterogenous urinary tract infections [21], though retrograde dissemination via pelvic veins or paravertebral nerve plexuses is also possible [22]. In this case, the patient’s MRI revealed that the anal fistula tract communicated with the sinus tract. The patient exhibited no urinary symptoms, and laboratory urinalysis results were normal. Based on these findings, we speculate that the onset of osteomyelitis in this patient may be associated with an exogenous Proteus mirabilis infection, which could be related to the anal fistula, prolonged bed rest due to paralysis, and poor perineal hygiene.

Chronic osteomyelitis is characterized by repeated infections, long treatment cycles, and high recurrence rates. It incurs high treatment costs, and the wound surface after debridement surgery is difficult to heal, which poses a great challenge to orthopedic surgeons and also brings psychological burdens to patients. There are numerous factors contributing to the recurrence of infections, among which the refractory sinus tract is one of the main factors in this case. Generally speaking, the sinus tract is a drainage channel extending from the infectious focus inside the bone marrow to the surface of the skin and is a high-risk factor for recurrent infections [23]-[25]. In orthopedic diseases, the presence of a sinus tract may reflect the degree of infection and local inflammatory response in bones and joints. However, the mechanism by which the sinus tract causes recurrent infections remains unclear. Some scholars believe that it may be related to the relatively poor condition of the soft tissues around the sinus tract. For example, the probability of the sinus tract occurring in the hip joint is relatively higher [26]. Moreover, in chronic osteomyelitis, the sinus tract is also a high-risk factor for the occurrence of malignant tumors, especially squamous cell carcinoma [27]. Therefore, special attention should be paid to patients with chronic osteomyelitis accompanied by sinus tracts in clinical practice. Although thorough debridement surgery can effectively remove the sinus tracts and necrotic tissues, due to the fact that chronic osteomyelitis reduces the local microcirculation and self-repair ability, for larger lesions, the effect of debridement surgery is unstable, the surgical wound recovers slowly, and the condition may even be aggravated. Hence, exploring methods to quickly promote the closure of sinus tracts has become one of the focuses in the treatment of chronic osteomyelitis.

Live Leech Therapy (LLT), a historical alternative therapy, involves the application of live leeches to a patient’s wound to treat diseases through their blood-sucking action [28]. In regions including China, India, Japan, and Central Asia, this therapy has been applied in modern medicine for inflammatory, metabolic, and cardiovascular diseases, as well as to promote wound healing, with reported effectiveness [29]. Its proposed mechanisms in wound healing, including its potential role in infected contexts, involve: 1) Decongestion: Removal of congested, potentially hypoxic blood and inflammatory exudate. 2) Pharmacological Action: Delivery of bioactive molecules with anti-inflammatory, anticoagulant, antiplatelet, vasodilatory, and potential bacteriostatic/bactericidal effects. 3) Mechanical Stimulation: Induced bleeding may stimulate localized angiogenesis and granulation tissue formation. While the evidence base specifically for LLT in osteomyelitis is limited primarily to case reports (like this one), the established biological effects provide a plausible rationale for its adjunctive use in refractory cases involving impaired microcirculation and persistent exudate, as seen in our patient [8][30][31]. Recent studies have demonstrated the effectiveness of LLT in various surgical applications. Nair et al. found that LLT significantly reduces pain in patients with infected wounds and promotes wound healing [32]. Cohn et al. applied LLT to patients with complex facial lacerations, achieving significant efficacy with no sequelae [33]. Some scholars propose that LLT may promote vasodilation, increase blood flow, and reduce inflammation and bacterial load by means of histamine in the leech saliva, thereby promoting wound healing. Gerivani et al’s study further confirmed the efficacy of LLT in chronic osteomyelitis, especially when used in combination with antibiotics, demonstrating significant reductions in bacterial colony counts, pathological assessments of bacterial-infected bone tissue, and serum levels of tumor necrosis factor-α (TNF-α) in rats with induced osteomyelitis [34]. Despite some studies noting potential complications of LT such as worsening infections, allergic reactions, and prolonged bleeding—with worsened infection being among the most commonly reported complications—no studies with sufficient sample sizes have confirmed a direct link between LLT and nosocomial infections [35][36]. Most reports indicate that improper procedures (such as a lack of strict aseptic techniques, reusing the same leeches, and failing to closely monitor patients during treatment) are the main causes of these complications. A large-scale clinical study indicates that properly performed LLT does not increase the incidence of nosocomial infections [37]. In the present case, all leeches used were strictly farmed medical-grade live leeches. During LLT, ceftazidime was continued for anti-infective coverage, which is effective against common pathogens associated with leech therapy, such as Aeromonas hydrophila. Throughout the treatment period, the patient’s infection markers were closely monitored, and no new infection was observed afterward. Thus, we contend that strict adherence to proper procedures can effectively avoid these complications. When performing LLT, strict aseptic principles should be followed, such as wearing gloves, using sterile toothed forceps for leech handling, and conducting timely follow-up checks on patients’ infection markers post-treatment to ensure the absence of recurrent infections. Furthermore, some critiques of LLT focus on psychological factors such as patient informed consent and compliance [38]. Patients may fear treatment involving blood-sucking parasites, resulting in lack of cooperation, treatment failure, or the emergence of complications. This underscores the need to fully explain the treatment procedure, precautions, and potential complications to patients and their families before applying LLT, and obtain their written consent. During treatment, close monitoring of the patient’s reactions and psychological support should be provided to alleviate any tension or fear. Properly performed Live Leech Therapy is an effective therapeutic approach, but its implementation requires strict adherence to aseptic principles and careful attention to the patient’s psychological responses to ensure its safety and efficacy. Additionally, although no recurrence was observed in this case at the two-month and six-month follow-ups, the relatively short follow-up period of only half year remains a limitation given the high recurrence rate of chronic osteomyelitis. Therefore, the long-term efficacy of leech therapy requires further validation.

We present a unique case of treating chronic ischial osteomyelitis with refractory sinus tracts through the combination of Live Leech Therapy (LLT) and antibacterial agents. Follow-up after discharge indicated satisfactory therapeutic outcomes, suggesting that LLT represents a potentially novel option for patients with chronic non-healing sinus tracts. This therapy is characterized by its ease of administration, low cost, significant efficacy, and high safety profile. As a traditional alternative medicine, LLT possesses potent biochemical effects. Although the treatment mechanisms remain incompletely elucidated and potential complications (e.g., infection, allergy) exist, these risks can be effectively mitigated through standardized protocols that include utilizing medicinal leeches certified as pathogen-free from regulated suppliers, ensuring strict adherence to aseptic techniques during application and wound management, conducting comprehensive pre-treatment screening for bleeding diatheses and allergic predispositions, and implementing close post-treatment clinical monitoring for adverse events. In this case, the rigorous implementation of these measures not only ensured a robust safety profile but also corroborated the observed therapeutic efficacy, demonstrating the feasibility of integrating systematic risk mitigation strategies into clinical practice. This approach offers new insights and directions for clinical treatment, warranting further research and exploration.

Yang-Fei Wei contributed to conceptualization, data analysis,, performed the literature search, and writing of the original draft paper, and reviewed the paper; Dan Zhang contributed to conceptualization, data collection, performed the literature search, patient care, and reviewed the paper; Ming Shi contributed to conceptualization, performed the literature search, and data collection; Jun-Jun Cao contributed to data collection; Song Li contributed to data analysis.

This study was supported by The Guangxi Key Research and Development Program (CN, Project Number: Guike AB25069079), The Development and Promotion Project of Appropriate Traditional Chinese Medicine Technologies in Guangxi (CN, Project Number: GZSY2025045) and The Youth Project of Guangxi University of Chinese Medicine Affiliated International Zhuang Medicine Hospital (CN, Project Number: 2022001).

The data sets generated and analyzed during the current study are not publicly available due to our research center policy, but are available from the corresponding author on reasonable request.

No approval was required. All authors complied with the ethics and policy of the journal.

Written informed consent was obtained from the patient for publication of this case report and any accompanying images. A copу of the written consent is available for review by the Editor-in-Chief of this journal.

The authors declare no competing interests.

*Co-first authors.

^#Corresponding author.