Anchoring Flap Suture Technique to Repair a Wound With Exposed Bone After Hip Disarticulation: A Case Report and Brief Review of the Literature

The avascular interface of bone presents a formidable challenge in the context of wound healing over exposed bone. Currently, various flap operations^1-3 and wound bed preparation strategies^4-7 are used to address these challenges in clinical practice. In certain situations, however, the surrounding soft tissue may not offer adequate support for securing a flap, thus impeding the success of flap operations.

The anchoring flap suture technique is a promising alternative for flap fixation. This approach has found widespread application in orthopedic surgery for ligament attachment to bone, facilitating the healing process at the interface of dissimilar tissues.⁸ Moreover, this anchoring technique has been adopted in diverse fields, such as ophthalmic surgery⁹ and plastic surgery.¹⁰

In a specific clinical scenario characterized by inadequate soft tissue coverage around exposed bone, the authors of the current case report successfully used the anchoring suture technique to secure a local flap to exposed bone. This innovative approach proved effective in the repair of this wound, yielding favorable therapeutic outcomes.

Informed consent was obtained from the patient and her spouse for publication of this case report, including the images shown.

A 39-year-old female with no prior significant medical history was involved in a traffic accident. During hospitalization in a peripheral facility, she developed necrotizing fasciitis of the left lower extremity caused by Acinetobacter baumannii. Despite aggressive debridement and subsequent below-knee amputation, the progressive infection could not be halted. While a left hip disarticulation eventually alleviated the life-threatening infection, it left behind a sizable wound of the left trunk.

Upon transfer to the authors’ facility 41 days after the accident, the patient presented with a 7% TBSA wound of the left trunk (Figure 1) and a 1% TBSA pressure ulcer on the lower back. Her condition remained stable at the time of admission. Laboratory test results were as follows: WBC count, 6.73×10⁹/L (reference range, 4.0×10⁹/L–10.0×10⁹/L); Hb, 126.0 g/L (reference range, 120.0 g/L–180.0 g/L); serum albumin level, 25.6 g/L (reference range, 40.0 g/L–55.0 g/L); prealbumin level, 0.09 g/L (reference range, 0.2 g/L–0.4 g/L); PCT level, 0.147 ng/mL (reference range, <0.05 ng/mL); and HbA_1c, 6.5% (reference range, 4.0%–6.0%). Physical examination revealed breakdown of the rectus muscle, external oblique muscle, and internal oblique muscle of the left abdominal wall. A portion of the peritoneum and the left pelvis were exposed within the wound.

On the second day after admission, the first debridement procedure was performed. Split-thickness skin grafts harvested from the scalp were used to cover a 2% TBSA wound (Figure 2A). NPWT was applied over the wound and skin graft area. On the ninth day after admission, the patient developed a high fever (39.8˚C). Laboratory results showed an elevated WBC count of 8.38×10⁹/L and a PCT level of 0.3 ng/mL, and gram-negative bacteria were observed in the blood smear. Intravenous antibiotics (tigecycline 50 mg, twice daily) were initiated based on the results of wound exudation microbial detection, which revealed multidrug-resistant A baumannii. The second surgical procedure was performed to debride the wound and further reduce the bacterial load.

On the 16th day after admission, a third operation was performed to repair the remaining soft tissue defects using split-thickness skin grafts harvested from the scalp (Figure 2B). In addition, during this operation split-thickness skin graft was used to address the pressure ulcer on the lower back. 

On the 30th day after admission the patient underwent a fourth operation, in which a wire saw was used to remove necrotic bone and prepare the wound bed (Figure 2C).

On the 45th day following admission, the final surgical intervention was performed to address the wound with exposed bone. As illustrated in the axial computed tomography image (Figure 3A), the remaining wounds primarily consisted of 2 distinct areas: the area with exposed bone (region 1) and the area with soft tissue defects (region 2). Intraoperatively, 4 steps were undertaken to repair the remaining wound. In step 1, soft tissue in region 2 was meticulously cleansed, and the skin and subcutaneous tissue were preserved to create a local flap (Figure 3B). In step 2, the prepared local flap was advanced to cover the appropriate area in region 1, and the area to be covered by the flap was marked. In step 3, exposed bone in region 1, which could not be covered by the prepared flap, was removed (Figure 3B). In step 4, the remaining wound was meticulously repaired using the prepared local flap. Subsequently, concerns arose about flap fixation owing to the compromised soft tissue around the exposed bone. The authors opted to anchor this skin flap directly to the exposed bone.

As shown in Figure 4, 3 holes were carefully drilled into the exposed bone using a Kirschner pin, with copious irrigation. The holes were placed 2 cm apart, with each hole also placed 1 cm from the bone margin. Hole diameter did not exceed 0.15 cm. Following the drilling process, surgical stainless steel wire sutures with needles, wrapped in silicone tubing, were passed through the 3 prepared holes to anchor the middle portion of the flap to the exposed bone. Other parts of this flap were sutured with 1-0 suture. The 1-0 suture was removed 14 days postoperatively. The steel wires were removed 17 days postoperatively, by which time wound healing by primary intention had been achieved. 

Nineteen days after admission, the patient presented with a series of symptoms, including loss of appetite, sadness, hopelessness, trouble sleeping, and exacerbation of phantom limb pain. A psychologist diagnosed the patient with posttraumatic stress disorder. Medication intervention, psychotherapy, and family medical care support were initiated to alleviate these symptoms.

The patient was discharged to a rehabilitation center for further treatment after achieving complete wound healing on day 59 (Figure 5A). Three months after discharge, the patient was able to walk on 1 leg with the aid of a 4-legged walker (Figure 5B). However, traumatic abdominal hernia due to the destruction of the abdominal musculature became evident.

This case report presents use of the anchoring flap suture technique to cover a wound with exposed bone; this wound healed by primary intention by 17 days postoperatively. Given the poor condition of the tissue surrounding the exposed bone in this patient, traditional sutures would have been inadequate to secure the flap. Therefore, the authors of this report devised an anchoring strategy to establish robust fixation between the soft tissue and bone, ensuring flap stability. 

Several key considerations should be noted regarding the anchoring strategy reported herein. First, to prevent excessive stress in the anchoring region, the flap should be sutured and secured with 1-0 suture to the adjacent soft tissue before fastening the anchors used to affix the flap to bone. Second, in this case the cortical bone margin was polished to expose more cancellous bone, thereby increasing the contact area between the bone and the flap. Third, steel wires, acting as anchors, were enveloped in silicone tubes to reduce the cutting stress on the bone and the flap. Additionally, a bellyband was used postoperatively to alleviate flap tension and ensure immobilization of the surgical region. 

Free flaps are typically considered to be the criterion standard for repairing wounds with exposed tendons, bones, joints, or prostheses after debridement. However, free flaps have associated drawbacks, such as prolonged surgical time, donor site morbidity, and the challenge of selecting recipient vessels in the context of poor local wound conditions. In contrast, pedicle flaps are an alternative means of addressing wounds with exposed bone or hardware in select cases.¹¹ 

In the current case, the authors opted to use a local flap to cover the wound with exposed bone after hip disarticulation for several reasons. First, pelvic stability was not compromised, which obviated the need for internal or external fixation. Second, no joints were exposed. Third, no necrotic bone remained. Fourth, there was no need to obliterate dead space. Finally, abundant soft tissues were available around the exposed bone for use as a local flap to cover the wound. Primary wound healing was achieved 17 days after the final operation, and no complications related to the local flap were observed after 3 months. 

Although local or distal skin flaps typically are used to repair wounds with exposed bone, poor soft tissue around the wound or a lack of expertise in free flap reconstruction may preclude the use of such flaps.¹² When used in combination with tissue engineering strategies, NPWT has shown superior outcomes in promoting healing of wounds with exposed bone in clinical and animal studies.^4,13 The application of platelet-derived fibrin or esterified hyaluronic acid matrix with NPWT has proved to be effective in both repairing wounds with exposed bone and accelerating wound healing.^4,13 Dermal substitutes combined with NPWT have also demonstrated efficacy in the repair of wounds with exposed bone or hardware.^6,7 Additionally, autogenic adipose-derived stem cells have been shown to promote wound bed vascularization and to enhance the healing of wounds with exposed bone in a rat model,¹⁴ offering an option for repairing bone-exposed wounds. 

The acute and progressive nature of necrotizing fasciitis contributes significantly to its high mortality rate. Early diagnosis of this condition, followed by urgent, aggressive debridement and antibiotic therapy is imperative. In some critical instances of severe necrotizing fasciitis of the lower extremities, hip disarticulation is necessary as a lifesaving measure.¹⁵ Unfortunately, prior to admission to the hospital of the authors of the current case report, the patient had to undergo left hip disarticulation owing to progressive infection caused by A baumannii. Although monomicrobial infections of necrotizing fasciitis are predominantly caused by gram-positive pathogens, infections involving gram-negative pathogens may be associated with increased mortality and elevated PCT levels.¹⁶A baumannii, an aerobic gram-negative bacillus found in soil, water, and health care settings, typically is associated with wound infections following severe trauma, such as automobile accidents or war injuries.^17,18 It has been reported that infections involving multidrug-resistant A baumannii are linked to increased mortality rates.¹⁹ The patient in the current case report rapidly developed an infection with multidrug-resistant A baumannii following a car accident. Throughout the patient’s stay in the authors’ hospital, multidrug-resistant A baumannii continued to be isolated from the wound and blood cultures. Aggressive debridement and tigecycline administration achieved a therapeutic effect for this patient during this hospital stay. 

In this report, it is challenging to draw definitive conclusions regarding use of the anchoring flap suture technique to repair a wound with exposed bone, primarily owing to the inherent limitations of case reports. Prospective studies involving a large sample size may be challenging to undertake owing to the unique circumstances of each patient. Although this is a singular case, it offers valuable insights into the management of wounds with exposed bone in patients with inadequate soft tissue for conventional flap fixation.

Severe trauma or life-threatening infections can result in the development of challenging wounds characterized by bone or implant exposure, necessitating flap coverage. In situations in which traditional sutures are inadequate owing to a lack of sufficient soft tissue, the anchoring suture technique for flap fixation is a dependable option. In the current case, neither short- nor long-term complications associated with the use of the anchoring flap suture technique were observed.