Salvage Masquelet Technique for Insufficient Bone Regeneration Following Chipping and Lengthening in Tibial Nonunion: A Case Report

Introduction

Nonunion occurs when proper bone healing fails, resulting in localized pain and persistent instability, which complicates treatment. Treatment becomes even more challenging when bone deformity or shortening is present. Selecting an appropriate treatment approach that promotes bone union and restores function is essential [1]. Tibial nonunion, in particular, represents a significant clinical challenge, with an incidence of approximately 7% following fractures [2]. It can also severely impair patients’ quality of life [3].

The chipping and lengthening technique is a method for addressing bone shortening and defects associated with delayed healing or nonunion, without the need for bone grafting [4]. This technique involves external fixation, followed by chipping of the bone at the nonunion site and gradual lengthening to stimulate bone union. Unlike conventional bone grafting, this technique preserves blood flow by maintaining the periosteum and utilizes physiological processes, including bone-forming cells and bone-promoting factors derived from bone marrow. Additionally, this technique allows simultaneous shortening, lengthening, and deformity correction and has been reported to be particularly beneficial in cases of leg length discrepancy.

The Masquelet technique is a 2-stage procedure for managing bone defects [5]. In the first stage, a cement spacer is placed in the bone defect to induce membrane formation, creating a vascular-rich environment. In the second stage, the cement spacer is removed and replaced with an autologous bone graft to promote bone regeneration. It is considered an effective approach, particularly for cases in which bone union has not been achieved with conventional treatments, including refractory nonunion, such as infectious nonunion [6]. Moreover, the Masquelet technique has been reported to achieve a bone union rate of approximately 86%, even in cases with large bone defects [6].

We encountered a case in which sufficient bone regeneration was not achieved following the chipping and lengthening technique for tibial nonunion with deformity and shortening. In this case, salvage treatment with the Masquelet technique resulted in a favorable outcome. The purpose of this report is to describe this rare case, which highlights the successful application of the Masquelet technique as a salvage procedure for a young patient with tibial nonunion after a failed chipping and lengthening technique [7].

Case Report

HISTORY OF PRESENT ILLNESS:

At the age of 19 years, the male patient experienced pain in the left lower leg, without any preceding trauma or significant medical history. A plain X-ray performed at a local hospital revealed a lesion in the left tibia (white arrows, Figure 1A–1C), leading to partial resection of the cortical bone, with curettage of the tumor (Figure 1D). Histopathological analysis confirmed a diagnosis of osteoid osteoma in the left tibia. At this time, congenital deformity of the left tibia (9° varus and 10° flexion), unrelated to the bone tumor, was identified (Figure 1A, 1B).

Subsequently, the patient sustained a fracture at the cortical defect after resection following a fall (Figure 2A), and medial plate fixation was performed (Figure 2B). Six months after surgery, delayed union and screw breakage were observed (Figure 2C, white arrow). The patient underwent reoperation, during which the plate was replaced with a longer, higher-strength plate, and autologous bone grafting was performed, resulting in bone union (Figure 2D, 2E).

Seventeen months after surgery, implant removal was performed following confirmation of bone union (Figure 3A). However, the patient later developed pain in the left lower leg, without any preceding trauma. Imaging revealed a fracture at a screw hole site (Figure 3B, 3C, white arrows). Conservative management was initiated at a local orthopedic clinic, but 5 months later, bone union had not been achieved, and the varus deformity and shortening had worsened. The patient was subsequently referred to our hospital for further treatment.

INITIAL EXAMINATION AND DIAGNOSIS:

At the age of 21 years, the patient underwent a physical examination during the initial visit to our hospital, which revealed a varus deformity of the left lower leg, along with swelling and redness, but no signs of infection. Imaging confirmed that the flexion deformity of the left tibia had improved to 7°, while the varus deformity had progressed to 18°, and the tibia was shortened by 20 mm, compared with the contralateral side (Figure 4A, 4B). A nonunion with some callus formation was observed around the distal shaft of the left tibia (Figure 4A–4C, white arrows). Magnetic resonance imaging findings ruled out infection or tumor recurrence.

CHIPPING AND LENGTHENING TECHNIQUE:

The chipping and lengthening technique was performed using an external fixator to treat nonunion and gradually correct the deformity and shortening. This technique was chosen because it promotes bone regeneration without the need for autologous bone grafts, offering a minimally invasive approach [4]. The proximal and distal bone fragments were attached to rings of a hexapod-type external fixator (Smith & Nephew Taylor spatial frame) and connected with 6 rods. A 2-cm skin incision was made directly above the nonunion, and the bone was chipped approximately 2 cm distal and proximal to the nonunion using a chisel while preserving the periosteum. An osteotomy was performed at the fibular shaft for bone lengthening (Figure 5A). After a 1-week latency period, gradual correction was performed over 3 weeks, according to a dedicated program (Figure 5B). Following the completion of gradual correction, the shortening was resolved, the varus deformity improved to 3°, and the flexion improved to 6°. The external fixator was subsequently converted to internal fixation using a plate (Synthes LCP [locking compression plate] medial distal tibia plate; Figure 5C, 5D).

Three weeks after the non-weight-bearing period, the patient was fitted with a patellar tendon-bearing brace and began partial weight-bearing. Additionally, low-intensity pulsed ultrasound therapy was administered, and the patient began full weight-bearing 6 weeks after surgery. However, although imaging showed signs of maturation in the distraction callus at both ends, consolidation in the center was not observed even 7 months postoperatively. Since the distraction callus had not yet matured, salvage surgery was planned (Figure 6A–6E).

SALVAGE SURGERY USING THE MASQUELET TECHNIQUE:

Seven months after the initial surgery, the Masquelet technique was chosen as a salvage procedure. In the first stage, the immature distraction callus was debrided, and a bone cement spacer was placed to induce membrane formation over a length of 2 cm (Figure 7A). No signs suggestive of infection, such as pus discharge, were observed intraoperatively, and the intraoperative culture results were negative. After a 1-month waiting period, the second-stage procedure was performed. The cement spacer was removed, and an autologous cancellous bone graft harvested from the iliac crest was transplanted into the induced membrane. To reduce soft tissue tension, the medial tibial plate was replaced with a smaller one, and an additional lateral plate was implanted for reinforcement. Subsequently, good bone formation was observed, without any loss of correction. Five months after the second-stage Masquelet procedure, the patient was able to walk without any problems and bear full weight without complications (Figure 7B, 7C).

Discussion

In this case, we treated tibial nonunion accompanied by varus deformity and shortening using the chipping and lengthening technique with a hexapod external fixator. However, adequate bone regeneration was not achieved, necessitating additional treatment.

The chipping and lengthening technique, first reported by Matsushita et al in 2007, is a method for treating nonunion, deformities, and shortening in a minimally invasive manner, without autologous bone grafts [4]. By crushing the bone at the nonunion site, this technique creates a favorable environment for bone regeneration and mobility. In this case, bone fragmentation was performed over a 2-cm range in both the distal and proximal directions based on imaging assessments of the affected area. However, bone regeneration did not occur as expected. According to several previous reports, the failure rate of the chipping and lengthening technique ranges from 0% to 16.6%. One possible explanation for the insufficient bone formation in the present case is that the extent of bone fragmentation was too narrow. The optimal fragmentation length in the chipping technique has not been clearly defined for specific bones, which may have contributed to suboptimal outcomes in this case. The biological effect of chipping is believed to be due to the introduction of precursor cells and cytokines derived from bone and bone marrow into the fragmented area [4]. Basic research has suggested that mesenchymal stem cell proliferation increases in the nonunion site after chipping [8]. Complete fragmentation can enhance the supply of mesenchymal and progenitor cells, as well as osteoinductive factors from bone marrow, to the fracture site. However, if fragmentation does not reach healthy bone marrow with adequate vascularity, its effect can be limited. Another potential contributing factor is impaired blood supply. It has been reported that repeated surgical interventions can compromise local vascularization, and that impaired blood flow can negatively affect bone healing [9]. However, we did not perform additional diagnostic tests, such as vascular imaging or bone perfusion studies, to directly assess the state of blood flow in this case, and we acknowledge this as a limitation of the report.

Another possible factor is the inappropriate evaluation of callus formation and the adjustment of lengthening speed. In the present case, after a 1-week waiting period, the rods between the external fixator rings were adjusted 4 times per day, according to a dedicated program, with gradual lengthening and correction performed at a rate of 1 mm per day, for a total lengthening of 20 mm. These distraction and correction rates fall within the commonly recommended range [10–12]. However, studies have reported no definitive threshold for the optimal distraction rate, as it varies among cases [13,14]. Aldegheri et al emphasized that controlled distraction is essential, and that the distraction speed should be adjusted based on careful observation of ossification progression [11]. In the present case, improper evaluation of callus formation and inadequate adjustment of the distraction rate may have contributed to the insufficient bone formation. Various factors can prolong distraction periods, including insufficient fixation, reduced blood supply to the bone and surrounding soft tissues, and underlying conditions [11,15,16]. One contributing factor in this case may have been the patient’s history of trauma and multiple surgeries, which likely led to impaired vascularization and scarring of the bone and surrounding soft tissues, negatively impacting bone formation.

To address poor bone regeneration, several alternative interventions have been reported, including extracorporeal shock wave therapy, ultrasound stimulation, platelet-rich plasma, bone marrow mesenchymal stem cells, local injection of bone morphogenetic protein, and reverse dynamization [17,18]. For the tibial bone defect in the present case, the Masquelet technique was selected instead of other surgical methods, such as free vascularized fibular graft or Ilizarov bone transport, owing to its lower technical complexity, reduced donor-site morbidity and complication rates, and the potential for earlier functional recovery through a shorter treatment course [19,20,21]. The Masquelet technique was thus chosen as a salvage procedure, as it is considered a promising method for cases in which bone regeneration is challenging.

Originally introduced by Masquelet et al in 2000, the Masquelet technique is a 2-stage surgical approach for large bone defects [5]. In the first stage, a cement spacer is implanted into the defect site to induce the formation of a vascularized membrane with osteogenic potential. In the second stage, the cement spacer is removed, and an autologous bone graft is placed within the induced membrane [5,6]. Although the Masquelet technique requires 2 surgical procedures, which can be time-consuming and involve additional morbidity due to bone graft harvesting, it has been demonstrated to provide strong osteogenic effects and is particularly effective for large bone defects [6]. In this case, successful bone regeneration was ultimately achieved using the Masquelet method. The surgical workflow and stepwise procedure are outlined in Table 1. This technique is thus considered a viable salvage option when bone union cannot be attained through the chipping and lengthening technique.

Conclusions

The chipping and lengthening technique is a valuable method for treating nonunion with deformity and shortening. However, achieving successful treatment outcomes requires adequate fragmentation, proper evaluation of callus formation, and careful adjustment of the distraction rate. In this case, bone union was ultimately achieved using the Masquelet technique following inadequate bone regeneration with the chipping and lengthening technique, demonstrating its effectiveness as a salvage procedure.