Clinical Efficacy of Chess-Shaped Polymethyl Methacrylate–Ilizarov Technology for Severe Composite Tibial and Soft-Tissue Defects

Summary

This study evaluated the effectiveness of chess-shaped polymethyl methacrylate–Ilizarov technology for managing severe composite tibial and soft-tissue defects, without requiring complex soft-tissue procedures.

Abstract

This study evaluated the effectiveness of a combination technique for managing severe composite tibial and soft-tissue defects, without requiring complex soft-tissue procedures. A retrospective analysis was conducted on 33 patients with tibial and soft-tissue defects and Gustilo type IIIB open fractures treated between April 2017 and December 2023. The management protocol for all patients consisted of two stages. The first stage involved thorough debridement in the emergency department, removal of all free tibial bone fragments, and fixation with an external frame. The second stage involved Ilizarov bone transport, utilizing chess-shaped polymethyl methacrylate (PMMA) cement (thickness: approximately 1 cm) to fill the tibial bone defect. The PMMA was gradually removed until bone union was achieved. Bone union and soft-tissue healing were achieved in all patients, without the need for additional flap transplantation. The mean bone-union time was 7.5 ± 1.4 months, and the mean soft-tissue healing duration was 70.9 ± 24.1 days. The mean traction period was 105.3 ± 48.2 days, the mean external fixation time was 444.0 ± 137.2 days, and the mean external fixation index was 58.2 ± 23.1 days/cm. Using the Lower Extremity Functional Scale (LEFS) and 36-Item Short-Form Health Survey to evaluate functional scoring, the mean LEFS, physical health component, and mental health component scores were 59.8±13.9, 70.5±17.7, and 77.8±20.1, respectively. According to Paley’s classification of complications, there were 14 problems, 6 obstacles, and no sequelae. The chess-shaped PMMA–Ilizarov technique effectively treated composite tibial and soft-tissue defects. This approach facilitated the gradual regeneration and repair of bone and soft-tissue defects, avoided the need for additional skin flap transplantation, and achieved satisfactory clinical results.

Introduction

Bone and soft-tissue composite defects after open fractures are a major challenge for clinicians. The number of open fractures of the extremities caused by high-energy injuries is increasing, with soft-tissue coverage of the middle calf being the most common site^1,2, occurring in approximately 28.1% of cases³. Owing to the anatomical characteristics of the middle calf, including weak local soft tissue and relatively poor blood supply, severe open fractures of the tibia and fibula often result in bone and soft-tissue defects. These defects are prone to complications, such as bone infection and nonunion, making limb salvage treatment a significant challenge⁴. Several reconstructive approaches have been described in the literature, including flap transfer using the Masquelet or Ilizarov techniques, vascularized tissue transfer, and combinations of these techniques^5,6,7. However, apart from the Ilizarov technique, the use of other techniques requires good soft-tissue coverage, meaning that flap transplantation is also needed^8,9. Flap and bone grafting can cause secondary injury in patients, and the limited amount of autologous bone restricts the application of Masquelet technology¹⁰.

The Ilizarov technique, which involves bone transport through distraction histogenesis, is widely used for managing composite bone and soft-tissue loss^11,12. However, docking-site nonunion remains a common complication in these procedures. The most frequently reported risk factors for docking-site nonunion are prolonged time to docking, infection at the docking site, soft tissue interposition, and microvascular dysfunction¹³. In cases of open bone transport involving both bone and soft-tissue defects, skin invagination during bone transport and infection at the docking area are important causes of docking-site nonunion. While previous studies have focused on the treatment of docking sites, there have been few reports on strategies for preventing docking-site nonunion¹⁴. Local bone cement placement effectively prevents soft tissue interposition and anti-infection during transport¹⁵. Although placing a whole piece of bone cement can induce membrane formation, it still requires another surgery after a period of time to remove it, increasing the number of operations¹⁶. The current study improves this method by placing the bone cement in pieces. By taking advantage of the gradual healing of the wound during open transport, the bone cement can be removed piece by piece within the wound, allowing local occupancy to prevent soft-tissue embedding and eliminating the need for secondary removal surgery while simultaneously facilitating bone transport.

Study objective
The primary objective of this study was to evaluate the effectiveness of chess-shaped polymethyl methacrylate (PMMA) combined with the Ilizarov technique for treating severe composite tibial and soft-tissue defects. This method can achieve bone and soft-tissue repair through a single operation without the need for additional flap or bone grafting procedures. The method is applicable for severe lower-limb injuries where bone and soft-tissue defects are on the same plane, especially when flap transplantation is not feasible. In this approach, the PMMA is gradually removed during bone transport, allowing the induced membrane produced by the bone cement to improve the treatment effect.

Protocol

All procedures involving human participants were approved by the Ethics Committee of the Wuxi Ninth People’s Hospital affiliated with Soochow University (LW20220021). The reagents and the equipment used are listed in the Table of Materials.

1. Patient information

1. Include thirty-three patients with tibial and soft-tissue defects and Gustilo type IIIB open fractures treated between April 2017 and December 2023. Record the injury types, including 15 machinery crush injuries, 13 traffic accidents, 4 fall injuries, and 1 blast injury.
2. Document the mean length of the bony defect as 8.3 ± 2.9 cm (range: 4.0–15.5 cm) and the mean size of the soft-tissue defect as 143.5 ± 76.0 cm² (range: 8–360 cm²).
3. Inclusion and exclusion criteria
   1. Define the inclusion criteria as follows: (1) Gustilo type IIIB tibial fractures or fibular fractures with bone defects, (2) age greater than 18 years, and (3) follow-up period longer than 12 months.
   2. Define the exclusion criteria as follows: (1) amputation during the treatment process, (2) flap transplantation, and (3) removal of external fixation due to intolerance.

2. Surgical techniques

NOTE: The treatment was performed in two stages.

1. Stage 1
   1. Administer intravenous antibiotics immediately. Perform initial debridement of devitalized and contaminated tissues under loupe magnification using tourniquet control and irrigation with 9 L of saline.
   2. Remove all free tibial fragments to create segmental bone defects. Maintain the tibial length and stabilize the limb using an external fixator. Cover the remaining wounds with vacuum-sealed drains.
2. Stage 2
   1. Perform the second stage more than 7 days later under intrathecal anesthesia. Remove the external fixator and replace it with an Ilizarov ring external fixator.
   2. Prepare antibiotic-loaded PMMA cement by mixing vancomycin with premixed gentamicin cement (5 g vancomycin added to 40 g gentamicin cement containing 0.5 g gentamicin).
   3. Mold the mixture into a chess-like shape during the dough stage, forming cylindrical pieces approximately 1 cm thick and 3 cm in diameter. Wait approximately 5 min until the cement mixture fully hardens. Fill the entire cross-section and length of the tibial defect by stacking the cement pieces sequentially (Figure 1).
   4. Perform individual corticotomies at the proximal or distal site, depending on the location of the bone defect. Make a 1 cm incision, incise the periosteum, and transect the bone using an osteotome.
   5. Obtain anteroposterior and lateral X-rays of the tibia to confirm successful tibial osteotomy. Suture the incision directly. Leave the original soft-tissue wound open and wrap it with iodine-soaked gauze.
3. Bone transport and bone cement removal
   1. Initiate bone transport after 7 days at a distraction rate of 1 mm per day, divided into four sessions.
      NOTE: The actual distraction speed was limited in this patient series. Simultaneously, remove the most distal segment of bone cement. Disinfect the wound and change the dressing every 2 days until complete healing occurs.
   2. Continue the tibial transport. As the distal bone cement approaches the fractured tibial end, gradually remove the most distal segment of bone cement until it is completely eliminated.
      NOTE: The timing of removal should also be determined according to wound healing conditions. If the wound heals before the bone ends achieve contact, remove the bone cement when only a narrow width remains within the wound. Stop bone transport 1 week after the bone ends make contact.
4. Post-operative care
   1. Provide routine post-operative care, including pin-tract care, infection monitoring, pain management, weight-bearing guidance, and joint mobility exercises according to standard clinical protocols.
   2. Schedule regular follow-up visits and maintain communication with patients through phone calls or messaging when needed.
      NOTE: Frequent disinfection of the pin tract is not necessary. Cleanse the pin tract with saline during the early stage and keep it dry thereafter. If infection occurs at the pin-tract site, perform local disinfection and administer antibiotics.
5. External fixator removal
   1. Remove the external fixator when the following conditions are satisfied: (1) radiographic examination shows cortical continuity on at least three sides of the fractured bone; (2) the density of the transported new bone following osteotomy is comparable to that of normal bone; and (3) no significant discomfort is reported after 1 month of walking with a loosened external fixation pin.

3. Outcome evaluation

1. Primary outcomes
   1. Assess the duration of bone transport, time to bone union, and degree of wound healing to determine treatment outcomes. Record the duration of external fixation and calculate the external fixation index (EFI).
2. Quality of life assessment
   1. Assess patient quality of life at the final follow-up using the Lower Extremity Functional Scale (LEFS) and the 36 Item Short Form Health Survey (SF-36). Include evaluation of the total physical health component score (PCS) and the mental health component score (MCS) of the SF-36^17,18.
3. Complications
   1. Record complications according to the Paley classification and categorize them as problems (mild complications), obstacles, or sequelae¹⁹.
   2. Classify complications requiring additional surgical intervention as “problems”, those requiring supplementary surgical procedures for resolution as “obstacles”, and those persisting despite completion of treatment as “sequelae”.

Results

General results
The cohort included 24 men and 9 women, aged 24–76 years (mean: 46.5 ± 13.2 years). The follow-up period ranged from 13 to 51 months (mean: 20.0 ± 7.6 months). Successful reconstruction without infection recurrence was achieved in 32 (97%) cases, eliminating the need for soft-tissue grafting. One patient underwent skin grafting on the 52^nd post-operative day because he complained of difficulty in changing wound dressings. Three (9%) cases presented with nonunion at the dock...

Discussion

Our study demonstrated the effectiveness of combining PMMA with the Ilizarov techniques for treating severe composite tibial and soft-tissue defects. The chess-shaped PMMA, individually removed during bone transport, effectively prevented soft tissue interposition and facilitated bone union.

Both the Masquelet and Ilizarov techniques are widely employed for treating long-bone defects^5,21. However, the Masquelet technique, when addressi...

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
external frame	Tianjin Zhengtian Medical Equipment Co., Ltd.Tianjin, China	20202040779	Connecting rod, Fixed clamp
Ilizarov ring external fixator	Tianjin Zhengtian Medical Equipment Co., Ltd.Tianjin, China	20200148	Full ring
PMMA cement	Heraeus Company, Hanau, Germany	20223130966	/
vacuum-sealed drains	Wuhan VSD Medical Science & Technology Co., Ltd., Wuhan, China	6202018000	/
vancomycin	Eli Lilly Japan K.K,Seishin Laboratories	HJ20140174	/