Successful Correction of Lower-Limb Malunions Using Intramedullary Nailing and Chipping Osteotomy: A Case Series

Abstract

Case series

Patients: Male, 47-year-old • Male, 59-year-old • Male, 59-year-old

Final Diagnosis: Post traumatic malunion

Symptoms: Knee joint pain

Clinical Procedure: —

Specialty: Orthopedics and Traumatology

Objective: Unusual or unexpected effect of treatment

Background

Lower-limb fracture malunion can result in angular deformity that requires surgical correction. Chipping corrective osteotomy (CCO) is a novel method that involves a chipping technique at the center of rotation of angulation, followed by single-stage internal fixation. This case series describes 3 cases of correction of fracture malunion of the lower limb managed using combined CCO and intramedullary nail stabilization.

Case 1

A 47-year-old man with a 17° varus deformity of the left tibia from a past accident had left knee pain. CCO was performed, achieving bone union in 4 months. The Mikulicz line improved from −11% to 23%, and his knee became pain-free.

Case 2

A 59-year-old man with a 19° valgus deformity of the right tibia from a past accident had right knee pain. CCO was performed, achieving bone union in 11 months. The Mikulicz line improved from 119% to 72%, and he could perform daily activities pain-free.

Case 3

A 59-year-old man with a complex left distal femoral deformity (25° varus and 15° internal rotation) from a past accident had left knee pain. CCO was performed, achieving bone union in 8 months. The Mikulicz line improved from −52% to 4%, and he started enjoying jogging.

Conclusions

We performed CCO combined with intramedullary nail stabilization in 3 cases of post-traumatic angular and rotational malunion, achieving good clinical outcomes. This single-stage surgery is advantageous for bone healing and is cost-effective, making it a viable option for correcting long-bone malunion.

Introduction

Malunion of long-bone fractures is a challenging complication for trauma surgeons. Malunion is defined as a fracture that heals into a clinically unacceptable deformity, resulting in dysfunction [1]. For the tibial shaft, unacceptable parameters were defined as coronal or sagittal plane angulation greater than 5 degrees, internal rotation of 15 degrees or more, external rotation of 20 degrees or more, shortening greater than 1 cm, or displacement of over 50% of any segment at the fracture site [1]. Malunion incidence after tibial fracture treatment ranges from 0% to 68% with casting and functional bracing and up to 20% after intramedullary nail stabilization for distal tibial fractures [2]. While some patients with more than 10 degrees of tibial malunion in any plane are asymptomatic [3], surgeons should consider treatments for cases with painful functional deficits, unacceptable cosmetic appearance, or high risk of secondary osteoarthritis [4].

For malunion surgical management, osteotomies are the most commonly reported approach [2,4,5]. Single-plane deformities can be corrected by opening- or closing-wedge osteotomy at the deformity site or the center of rotation of angulation (CORA) [2]. Although multiplane deformity surgeries are more difficult to plan and perform, multiplane osteotomies can be performed [2]. The effectiveness of clam shell osteotomy, a technique consisting of 3 cuts, including a single longitudinal cut and 2 transverse bone cuts, has recently been reported [5]. In addition to osteotomies, gradual correction using external fixators, such as Ilizarov [6] and Taylor Spatial Frames4[7], has also been reported.

Recently, Miyamoto and Watanabe reported a novel procedure known as chipping corrective osteotomy (CCO) for correcting long-bone malunions [8]. CCO has been reported as a method for angular deformity correction, where the chipping technique is performed at the CORA, followed by single-stage internal fixation [8]. Originally, the chipping technique was used for nonunion surgery with deformity and shortening of long bones [9]. CCO has the advantage that it can be applied not only to angular but also to rotational malunion, except for shortening [8]. In the original method reported by Miyamoto et al, the correction was performed using an external fixator intraoperatively after chipping, followed by definitive fixation with a minimally invasive plate osteosynthesis technique in a subsequent surgery [8]. Severe deformities resulting from neglected fractures often require advanced surgical approaches [10]. However, less invasive techniques such as CCO may offer an alternative, particularly for preserving joint mobility in younger, more active patients.

Here, we report 3 cases of long-bone malunion with angular deformity or both angular and rotational deformities, treated with CCO using an intramedullary nail for final fixation instead of a plate. Only a few papers have reported this method [11,12], and its outcomes are not well understood. We hypothesized that CCO using an intramedullary nail could minimize damage to the soft tissue around the CORA, which could contribute to early bone healing and an increase in patient satisfaction. Here, we present 3 cases of long-bone malunion treated with CCO using an intramedullary nail and evaluate this new surgical technique. This case series describes 3 cases of correction of fracture malunion of the lower limb managed using combined CCO and intramedullary nail stabilization.

Case Reports

Case 1

A 47-year-old man visited our outpatient clinic with bilateral knee pain, which began 1 month after getting off a bus. At the age of 20, he had an open fracture of the right tibia and closed fractures of the right femur and left tibia in a motorcycle accident. Surgical treatment was performed for the right femoral and tibial fractures, whereas conservative treatment was performed for the left tibial fracture. All the fractures healed; however, an 11° valgus deformity in the right tibia and a 17° varus deformity in the left tibia were noted. During his initial visit to our outpatient clinic, full-leg-length standing radiographs were obtained, and the Mikulicz line, defined as 0% when the weight-bearing axis crossed the medial point of the tibial plateau, was measured to evaluate alignment [13]. His Mikulicz line passed through 79% of his right limb and −11% of his left limb, positioned more medially than the medial joint surface of the tibia. Leg length discrepancy was defined as the difference in spinal malleolar distance (SMD) between the affected and unaffected sides, as measured on full-leg-length standing radiographs. His SMD values showed minimal differences.

To determine the appropriate surgical procedure, a knee osteotomy surgeon was consulted. When the correction angle exceeds 12.5° to 13.4°, the patellar position can be significantly affected, potentially leading to postoperative patellofemoral joint pain [14]. Therefore, it was concluded that knee osteotomy would be difficult, as the corrective angles exceeded this range. Informed consent was obtained before surgery, and CCO was chosen from the available treatment options presented. At first, the patient considered undergoing bilateral surgeries. However, he ultimately decided to undergo surgery on his left limb, which was the side with severe pain, while he was observed for right knee osteoarthritis.

Surgery was performed with the patient in the supine position and using the suprapatellar approach to facilitate maintaining alignment during reaming and inserting the nail. For chipping, a vertical skin incision approximately 2 cm in length was made at the level of the CORA, and the bone approximately 3–4 cm area around the CORA was chipped into small pieces using a chisel and hammer, taking care not to remove the bone from the soft tissue (Figure 1). The chipping should be extended to healthy bones both proximally and distally. During chipping, the chisel must be moved from the intramedullary canal to the cortex to avoid damaging the periosteum [8]. After acquiring sufficient CORA movement, it was confirmed that the alignment could be reduced as intended. During inserting a guidewire, it should pass through the center of the bone axis at both proximal and distal sites. The blocker pin technique was applied to optimize the guidewire position. The assistant held the affected bone in the desired alignment until reaming and antegrade intramedullary nail (Expert Tibia Nail, Depuy Synthes, West Chester, USA) insertion. For maintaining proper alignment easily during intramedullary nail stabilization, an intraoperative temporal external fixator was prepared. However, good alignment was maintained without using it. Finally, surgery was completed by inserting a sufficient number of proximal and distal screws to ensure good fixation.

Figure 1.

Intraoperative pictures during chipping in case 1. The white arrow indicates a vertical skin incision approximately 2 cm in length at the level of the center of rotation of angulation (CORA). Chipping was performed with a chisel from the intramedullary canal to the cortex to avoid damaging the periosteum.

Postoperatively, low-intensity pulsed ultrasound was applied until radiographic bone healing was confirmed. Postoperative range-of-motion exercises were performed as soon as possible. One-third partial weight bearing was allowed 1 month after surgery. Weight-bearing gradually increased because the patient had no pain, and callus formation was observed on radiography. Full weight-bearing was permitted 2.5 months after surgery. Radiographic bone healing, defined as the presence of a bridging callus on at least 3 of the 4 cortices in anteroposterior and lateral views [15], was achieved 4 months after surgery. One year after surgery, the Mikulicz line had improved to 23% from −11% before surgery (Figure 2).

Figure 2.

Preoperative and postoperative X-rays of Case 1. (A) X-rays taken preoperatively, postoperatively, and at final follow-up. Preoperative varus deformity was 17°. Radiographic bone healing was achieved 4 months after surgery. (B) Full-leg-length standing radiographs taken preoperatively and 1 year after surgery. The dotted lines indicate the Mikulicz lines, which improved to 23% from −11%.

To evaluate patients’ health conditions preoperatively and every year after surgery, we used the Short Form-36 (SF-36), which is a generic measure of health status, and a self-report questionnaire consisting of 36 items that assess physical and mental health. The raw scores of all 36 items were categorized into 3 summary component scores: physical component summary (PCS), mental component summary (MCS), and role and social component summary (RCS) scores [16]. The preoperative and 1-year postoperative PCS scores changed from 47.6 to 41.4, MCS scores changed from 47.2 to 45.9, and RCS scores changed from 51.8 to 51.2. Four years after surgery, at the final follow-up, he was able to walk without any left knee pain but felt contralateral knee pain. Although contralateral knee surgery was proposed, he chose conservative treatment as he did not want to be absent from his job anymore.

Case 2

A 59-year-old man presented to our outpatient clinic with chronic right knee pain. At age 18 years, he experienced diaphyseal fractures of the right proximal tibia and fibula during a traffic accident. Open reduction and internal fixation were performed on the tibial fracture; however, nonunion occurred. The following year, revision surgery was performed, and the fracture healed but resulted in a 19° valgus deformity. At age 20 years, he had another traffic accident, which caused an open fracture of his left femur and ruptured his left sciatic nerve. During the surgery, the left femur was shortened by 2 cm to repair the left sciatic nerve. After that, walking without a brace became difficult for him. At his initial visit to our outpatient clinic, the Mikulicz line on his full-leg-length standing radiographs passed 119% more laterally than the lateral end of the tibial plateau. The right SMD was 2.3 cm longer than the left.

The surgical procedure was selected through informed consent, in the same manner as in Case 1. For right tibial malunion, CCO was performed with an antegrade intramedullary nail (Tibia Nail Advanced, Depuy Synthes, West Chester, USA). The surgery was performed as described in Case 1, except that the lateral parapatellar approach was used.

Postoperative low-intensity pulsed ultrasound was also applied until radiographic bone healing. The patient started partial weight bearing with 10 kg 10 days after surgery, earlier than our usual protocol, due to compromised function of his left limb from a previous sciatic nerve injury. Weight-bearing gradually increased, and full weight-bearing was possible 4.5 months after surgery. Radiographic bone healing was achieved 11 months after surgery. One year after surgery, the Mikulicz line had improved to 72% from 119% before surgery (Figure 3). The preoperative and 1-year postoperative PCS scores changed from 45.3 to 53.3, MCS scores changed from 47.0 to 40.0, and RCS scores changed from 53.3 to 60.6. At the final follow-up, 1.5 years after surgery, he did not experience any right knee pain and could walk smoothly.

Figure 3.

Preoperative and postoperative X-rays of Case 2. (A) X-rays taken preoperatively, postoperatively, and at final follow-up. Preoperative valgus deformity was 19°. Radiographic bone healing was performed 11 months after surgery. (B) Full-leg-length standing radiographs taken preoperatively and 1 year after surgery. The dotted lines indicate the Mikulicz lines, which improved to 72% from 119%.

Case 3

A 59-year-old man visited our outpatient clinic with left knee pain following a fall. At 17 years old, he was involved in a motorcycle accident and sustained a left distal femoral shaft fracture. Internal fixation with a distal femoral plate was performed; however, the implant was removed 4 months after surgery because of severe left knee motion pain. The fracture healed; however, a 25° varus and 15° external rotation deformity remained. At his initial visit to our outpatient clinic, the Mikulicz line on his full-length standing radiographs passed −52%, more medially than the medial joint surface of the tibia. The SMD was 4.5 cm shorter on the affected side.

Similarly to the other cases, CCO was selected for the left femoral malunion and performed with a retrograde intramedullary nail (Retrograde Femoral Nail Advanced, Depuy Synthes, West Chester, USA) (Figure 4).

Figure 4.

Intraoperative fluoroscopy images of pre-chipping, post-chipping, and correction in case 3. The black arrows show the center of rotation of angulation (CORA). Before chipping, the chisel was inserted into the intramedullary canal. Chipping was extended to the healthy bones both proximally and distally. After chipping, we confirmed sufficient bone movement to achieve ideal alignment easily.

Low-intensity pulsed ultrasound was also administered. We allowed one-third partial weight bearing 6 weeks after surgery, and weight bearing was gradually increased. Radiographic bone healing was confirmed 8 months after surgery, and full weight bearing was permitted. One year after surgery, the Mikulicz line had improved from −52% before surgery to 4%, and external rotation compared to the healthy side improved from 15° to 4° on the CT scan. The difference in SMD improved to be 2.0 cm shorter than on the healthy side (Figure 5). The preoperative and 1-year postoperative PCS scores changed from 34.4 to 49.8, MCS scores changed from 68.5 to 64.3, and RCS scores changed from 46.2 to 52.7. At the final follow-up, 1.5 years after surgery, he reported no left knee pain and started enjoying jogging for the first time since his traffic accident at 17 years old.

Figure 5.

Preoperative and postoperative X-rays of Case 3. (A) X-rays taken preoperatively, postoperatively, and at final follow-up. Preoperative varus deformity was 25°. Radiographic bone healing was confirmed 8 months after surgery. (B) Full-leg-length standing radiographs taken preoperatively and 1 year after the operation. The dotted lines indicate the Mikulicz lines, which improved to 4% from −52%.

The demographic data and surgical details of the patients included in this study are shown in Table 1, and a summary of clinical and radiographic outcomes is presented in Table 2.

Table 1.

Demographic data and surgical details of the patients.

Case	Age	Sex	Bone	Limb	Cause of deformity	Deformity			Surgery time (min)	Breeding (ml)
						Coronal	Rotational	Limb length discrepancy (mm)
1	47	Male	Tibia	Left	Malunion	Varus (17°)	–	+1	236	350
2	59	Male	Tibia	Right	Malunion	Valgus (19°)	–	+23	223	300
3	59	Male	Femur	Left	Malunion	Varus (25°)	External (25°)	−45	200	235
Average (SD)	55±6.9								220±18	295±58

SD – standard deviation.

Table 2.

Summary of clinical and radiographic outcomes.

Case	Follow-up	Radiographic	ROM of the knee (extension/flexion)		Mikulicz line			Lengthening (mm)
	Period (Months)	Bone healing (Months)	Preoperative	Final follow-up	Preoperative (%)	After 1 year (%)	Improvement (%)
1	48	4	0/130°	0/130°	−11	23	34	+19
2	21	11	−20/120°	−5/120°	119	72	47	+14
3	12	8	0/120°	0/130°	−52	4	56	+25
Average (SD)	27±19	7.7±3.5					45.7±11.1	+19.3±5.5

ROM – range of motion; SD – standard deviation.

Differences in PCS, MCS, and RCS scores before and 1 year after surgery were statistically compared using a paired t test. Statistical analyses were performed using EZR (Saitama Medical Center, Jichi Medical University, Saitama, Japan). Values with p<0.05 were considered statistically significant. Both the PCS and RCS 1 year after surgery showed improvements. However, none of these scores showed significant preoperative versus postoperative differences (Figure 6).

Figure 6.

Mean Short Form-36 (SF-36) scores were recorded preoperatively and 1 year postoperatively. Both the physical component summary (PCS) and the role/social component summary (RCS) showed improvements. None of these scores showed significant differences between preoperative and postoperative measurements. (A) Physical component summary (PCS). (B) Mental component summary (MCS). (C) Role/social component summary (RCS).

Discussion

CCO combined with intramedullary nail stabilization was applied, successfully achieving bone union without autologous bone grafting and good clinical satisfaction in all 3 cases of long-bone malunion in the lower limbs with angular deformities or both angular and rotational deformities.

Osteotomy in the CORA and gradual correction using an external fixator are common surgical treatments for post-traumatic malunion. For single-plane deformities, opening- or closing-wedge osteotomy has advanced [2]. The disadvantages of this treatment method are that it requires an autologous bone graft, accurately sized osteotomy and bone grafts, and a compression technique during plating [8]. Oblique osteotomy is useful for multiplane deformities, with a report indicating that 10 out of 12 patients achieved excellent results [17]. Clamshell osteotomy has also shown good results and can be applied in most cases of diaphyseal malunion with adequate soft-tissue coverage [5]. However, these osteotomies cannot prevent soft-tissue invasion around the cutting site. Conversely, gradual correction using an external fixator has several advantages. It can achieve accurate correction as planned without the risk of paralysis and is suitable for cases that require correction with lengthening [2]. However, a report on fresh tibial shaft fractures has indicated that treatment with an intramedullary nail is associated with a shorter hospital stay compared to external fixation [18]. A prolonged treatment period, delayed return to social activities, and high costs due to long-term hospitalization are disadvantages. The use of an external fixator also carries a risk of pin site infection [19].

In comparison, CCO offers several advantages. The chipping technique provides more progenitor cells from the bone marrow, which in turn accelerates bone healing without the need for autologous bone grafting [9]. Moreover, the treatment period requiring hospital admission can be shortened because CCO is not a staged surgery and does not require postoperative external fixation. However, a disadvantage of CCO is that it cannot be used in cases where bone lengthening is required. For cases requiring more than 10 mm lengthening, both chipping and gradual lengthening techniques at different parts of the correction site are necessary [20].

In the report by Miyamoto et al [8], which described 6 cases and 8 limbs of malunion treated with CCO combined with the minimally invasive plate osteosynthesis technique, the average bone healing period was 3.5 months, which was shorter than that in our report. Conversely, the correction angle of the Mikulicz line was an average of 29.3% in their report, which was smaller than the 45.7% in our report. All their cases had varus deformities, whereas our report included a valgus deformity as well, indicating different conditions. We hypothesized that our method using intramedullary nails, with less soft-tissue invasion, would be favorable for early bone healing. However, to resolve this issue, further accumulation of cases is necessary.

The most important therapeutic achievement of this procedure is the correction of the malunited bone. We believe that straightening the affected bone is straightforward when the nail is inserted in the correct position. Using this technique, the mechanical axis and leg length discrepancy during standing can be corrected to some extent. However, surgeons cannot fully predict postoperative standing alignment until patients can stand and walk with full weight bearing. Moreover, while knee pain can be reduced after alignment-corrective surgery, it may persist because of pre-existing knee osteoarthritis. For such patients, the next step in surgical treatment, such as arthroplasty or knee osteotomy, should be considered. Straightening the bone is also valuable because it facilitates joint surgeries even if it cannot completely relieve knee pain. Thus, we usually decide on the surgical procedure after obtaining sufficient informed consent, explaining that not all symptoms may be relieved and that additional surgery may be necessary in some cases. Fortunately, in all 3 of our cases, additional surgery was not needed at the latest follow-up because knee pain had diminished, although a longer follow-up should be performed.

In this study, the average postoperative SF-36 scores for the PCS and RCS improved. This suggests that the patients felt less pain preoperatively and were able to return to social activities at a higher level than preoperatively. Conversely, although significant differences were not noted, the mean MCS scores decreased compared with the preoperative scores. In this case series, the patient in Case 1 had contralateral knee osteoarthritis due to a motorcycle accident at age 20. Initially, he considered undergoing bilateral surgeries; however, conservative treatment was chosen for his right knee. The patient in Case 2 had contralateral sciatic nerve paralysis due to a traffic accident at age 20, and it was difficult for him to walk without a leg brace. In these situations, limited weight-bearing on the operative side for several months or post-trauma problems on the opposite side might be negative factors that reduce mental scores, although they did not feel knee pain on their operative side.

This study has several limitations. First, the follow-up period was short. Changing standing alignment due to surgery can affect not only the operated-side knee but also the contralateral knee, as well as the ipsilateral or contralateral hip and ankle. In this study, these progressive problems were not observed during short-term follow-up; however, a longer follow-up is necessary. Second, this study lacks comparisons with other methods, such as other osteotomies or gradual correction using an external fixator. When choosing a surgical procedure, it is important to understand the differences among methods in terms of hospitalization, time to return to work, bone healing period, and postoperative patient satisfaction. To clarify these differences, further research, such as studies with larger patient cohorts or comparisons with alternative surgical techniques, is needed.

Conclusions

We performed CCO combined with intramedullary nail stabilization in 3 cases of post-traumatic angular and rotational malunion, achieving good clinical outcomes. This single-stage surgery is advantageous for bone healing without autologous bone grafting, is cost-effective, and involves less surgical invasiveness, making it a viable option for correcting long-bone malunion.