Internal Brace Fixation Technique for Lisfranc Injury: A Retrospective Study

Introduction

Lisfranc injuries account for approximately 0.2% of adult fractures. The Lisfranc joint is a crucial component of the midfoot, located between the metatarsal and tarsal bones, forming a unique ‘arch’ and ‘mortise-like’ structure, and maintaining critical longitudinal joint stability in the transverse plane. Lisfranc injuries include tarsometatarsal joint dislocation or fractures with dislocation, along with interosseous ligament damage in the midfoot joints, as well as damage to the bone and ligament structures and compound injuries [1–3]. It is important to assess the injury mechanism and midfoot pain/swelling/ecchymosis and perform standing X-rays or computed tomography scans to avoid misdiagnosis or delayed diagnosis. The conservative treatment of mild Lisfranc injuries included plaster immobilization, wearing of appropriate footwear, rehabilitation, and medication such as nonsteroidal oral analgesics and steroid injections. Surgery with open reduction and internal fixation and fusion is indicated if conservative treatment fails to improve symptoms and stability. If not promptly treated or if managed improperly, Lisfranc injuries can lead to changes in the arch of the foot, instability of the midfoot, and traumatic arthritis, severely impacting the patient’s quality of life. Surgical treatment is an effective and satisfactory method [4]. Unstable Lisfranc injuries can involve the middle column, resulting in rupture of the Lisfranc ligament or avulsion fractures. Typically, screws are used to stabilize the Lisfranc joint across the joint. However, considering the anatomical structure, there is inherent micromotion between the medial cuneiform and the base of the second metatarsal, and screw fixation is a rigid fixation method that can lead to joint stiffness, weight-bearing pain, and the risk of screw breakage. With the development of elastic fixation techniques, surgical fixation methods such as suture buttons have been adopted [5]. The use of linear fiber band fixation (InternalBrace) has emerged [6]. Binding the Lisfranc joint and first and second metatarsal joints for elastic fixation can maintain the stiffness of the InternalBrace and provide sufficient stability; however, the tension when the anchor is inserted into the intermediate cuneiform affects midfoot function recovery. Nonetheless, the optimal choice of surgical method remains controversial. This retrospective case series aimed to evaluate the clinical and functional outcomes of InternalBrace fixation in Lisfranc injury treatment and reports our preliminary findings.

Material and Methods

ETHICS STATEMENT:

IRB approval was obtained for this study. Ethics approval and the details of patient informed consent were given by the Medical Ethics Committee of Dongguan Hospital of Traditional Chinese Medicine (reference number PJ [2023] No. 68).

METHODS AND STUDY POPULATION:

We performed retrospective analysis of clinical data of 58 patients in a tertiary academic teaching hospital from January 2019 to September 2022. The inclusion criteria were: closed injuries, CT indicating Lisfranc injuries, MRI indicating Lisfranc ligament damage, stress X-rays showing Lisfranc joint displacement exceeding 2 mm from the anatomical position, and lateral X-rays showing a distance greater than 15° from the metatarsal angle [7]. Its ICD classification is XIX S93. The diagnostic inclusion criteria were all controlled by the same group of senior chief foot and ankle surgeons. The exclusion criteria were: open injuries, concomitant fractures of the hindfoot and ankle, history of previous foot surgeries, and presence of severe medical conditions, tumors, infections, or conditions affecting fracture healing. All patients were diagnosed by the same team of experienced foot and ankle surgeons.

The patients’ ages ranged from 19 to 62 years, with a mean age of 34.6±9.4 years. There were 39 males and 19 females. The distribution of the injuries was: 20 cases on the left side, 38 cases on the right side, and 0 cases on both sides. The causes of injury were falls in 12 cases, traffic accidents in 27 cases, and sports injuries in 19 cases. The duration of symptoms ranged from 5 to 14 days, with a mean duration of 7.6±1.9 days. According to the Myerson classification [8], there were 10 cases of type A, 33 cases of type B, and 15 cases of type C. All patients were followed up for at least 1 year (mean follow-up time: 16.9±3.0 months), as shown in Table 1.

INTERVENTION:

The InternalBrace fixation technique was performed using the InternalBrace system (Arthrex, Naples, FL, USA) with 2 sutures anchors (4.75×19.1 mm with #2 FiberTape@,4.75×19.1 mm with closed PEEK Eyelet and FiberTape@ Loop). The plates used in the surgery were the metal locking plate system from Boneunion (Xiamen) Medical Device Co., Ltd., made of titanium alloy, with screw diameters of 2.7 mm and lengths ranging from 10 to 30 mm. The Kirschner wires were from Shanghai Puwei Medical Instrument Factory Co., Ltd., made of titanium alloy, with specifications of diameter 1.5–2.0 mm and length 180 mm.

SURGICAL TECHNIQUE:

All patients underwent comprehensive preoperative imaging examinations (including anteroposterior X-ray, CT scans with 3D reconstruction, and MRI) to accurately determine the type of injury. They were advised to rest in bed, elevate the affected limb, immobilize it with a cast, and receive symptomatic treatment. Surgery was performed if the swelling subsided and the wrinkle test yielded positive results. As a routine measure, intravenous antibiotic prophylaxis was administered 30 min before surgery to prevent infection [9]. All operations were performed by the same team of experienced senior foot and ankle surgeons.

Patients were placed in a supine position and received continuous epidural anesthesia. The surgical area was sterilized and draped. The incision was made on the medial side of the dorsal foot to expose and explore the fractures at the base of the first to third metatarsals, dislocation of the tarsometatarsal joints, and injuries to the Lisfranc ligament and interosseous ligament. Hematomas and soft tissues around the fracture site were cleared, and proximal metatarsal fractures and dislocations of the first to third tarsometatarsal joints were reduced under direct visualization using C-arm fluoroscopy. After satisfactory reduction, Kirschner wires were temporarily inserted to stabilize the first to third tarsometatarsal joints. A suitable mini-plate was placed on the dorsal side of the metatarsals, and holes were drilled and measured. Unstable tarsometatarsal joints (usually the first to third) were fixed with appropriate-length locking screws. In the medial side of the medial cuneiform, an appropriate position was selected, and after drilling, 1 InternalBrace anchor was inserted. Using a 2.5-mm Kirschner wire, another guide wire was drilled from the medial cuneiform to the lateral side of the base of the second metatarsal (if the fracture site was unstable, the hole could be drilled slightly further to the harder bone). The guide wire was used to create a bone tunnel, and the suture of the anchor was passed through the tunnel to the proximal end of the second metatarsal (Figure 1A). Using a 2.5-mm Kirschner wire, another hole was drilled from the proximal end of the second metatarsal to the medial side of the base of the first metatarsal, and the suture of the anchor was passed through the tunnel to the medial side of the first metatarsal (Figure 1B). In the dorsal side of the intermediate cuneiform, an appropriate position was selected, and after drilling, the suture was passed through another InternalBrace anchor, tightened, and compressed into the intermediate cuneiform (Figure 1C, 1D). The stability of the Lisfranc joint and tarsometatarsal joint was checked and deemed satisfactory. Figure 2 is a schematic diagram of the InternalBrace fixation technique for Lisfranc injury. Finally, a small incision was made at the fourth and fifth tarsometatarsal joints on the dorsal foot to explore and reduce any dislocation, and 2–3 percutaneous Kirschner wires (with a diameter of 1.5 mm or 2.0 mm) were used for fixation (Figures 3, 4). The incision was then rinsed and closed. The ankle joint was immobilized in a neutral position with a short leg cast.

POSTOPERATIVE MANAGEMENT:

All patients received prophylactic antibiotics, elevation of the affected limb, immobilization with a cast, regular dressing changes to keep the incision dry, and the use of anti-inflammatory drugs to reduce foot swelling [10]. All patients had the affected limb immobilized with a short leg cast for 2-3 weeks, with no weight-bearing allowed. After that, the Kirschner wires on the lateral side of the foot were removed at 6–8 weeks postoperatively, and rehabilitation exercises with 30–50% weight-bearing were initiated with the assistance of a non-weight-bearing ankle brace. Weight-bearing was gradually increased until full weight-bearing training was achieved at 12 weeks. X-rays of the foot were taken immediately after surgery and at 6, 12, and 24 weeks postoperatively, with additional CT scans of the foot if necessary.

STATISTICAL ANALYSIS:

Measurement data are expressed by mean±standard deviation. The Shapiro-Wilk normality test was first performed to check for normal distributions. Continuous variables with non-normal distributions were analyzed with the Mann-Whitney U test. Sample size estimation was done in G*Power software (Germany) based on the AOFAS scores in a previous study [11]. Allocation of the 58 patients was calculated to provide 90% power (actual power 0.953) to test the hypothesis regarding the validated patient-reported outcome measure (AOFAS). The 95% confidence interval (a type-I error rate of 0.05) was used to determine whether there was a difference in the AOFAS. Ten-point differences in the AOFAS [12] were recorded as the minimal clinically important change score (MCID), and the estimated dropout rate was 15%. We included 68 patients in the study and 58 patients completed the final follow-up. SPSS 20.0 for Mac OSX (SPSS, Inc, Chicago, IL, USA) was used for statistical processing and one-way analysis of variance (ANOVA) or the t test was used. Homogeneity of the groups at baseline was evaluated with a chi-square test for categorical variables and with ANOVA for continuous variables. A multivariate linear model was used to assess covariables. Statistical significance was defined as P<0.05.The statistical methods were reviewed by the Biostatistics Expert Group at the tertiary academic teaching hospital.

ASSESSMENT VARIABLES:

All patient observation indicators were evaluated using a blind method. All patients were followed up for at least 1 year, with an average follow-up time of 16.9±3.0 months. Postoperative foot anteroposterior and lateral X-ray images, as well as oblique views and CT scans at 6, 12, and 24 weeks postoperatively, were used to assess reduction and fracture healing. Anatomic reduction was indicated when there was less than 2 mm of displacement in the tarsometatarsal and Lisfranc joints, and complete restoration of the alignment of the metatarsal axis. Signs of traumatic arthritis were indicated by the narrowing of joint spaces, bone spur formation, subchondral cystic changes, and sclerosis on X-ray images, as well as tenderness and limited mobility in the Lisfranc joint [13]. Visual analog scores (VAS), American Orthopaedic Foot and Ankle Society (AOFAS) scores, and Tegner scores were used at 3, 6, and 12 months, and at the final follow-up. VAS scores ranged from 0 to 10 [14], with higher scores indicating higher pain intensity. AOFAS scores assessed foot joint function recovery [15]. A score above 90 was classified as excellent, 80–89 as good, 70–79 as fair, and below 70 as poor. Tegner scores ranged from 0 to 10 [16], with higher scores indicating higher activity levels. Early postoperative complications (superficial infections, deep infections, and wound necrosis) and late complications (posttraumatic arthritis, screw breakage, fixation failure, stiffness, and chronic pain) were recorded. The questionnaire is a very effective tool for data collection in terms of reliability and validity of the data (Cronbach’s Alpha: 0.71, Kaiser-Meyer-Olkin: 0.706, Bartlett P<0.05). Several studies have investigated the reliability and validity of VAS, AOFAS, and the Tegner questionnaire in patients with ankle and foot disorders [17-20]. Our study revealed an acceptable reliability and validity for the Persian version of the questionnaire in both subjective and objective domains.

Results

We included 68 patients in the study and 58 patients completed the final follow-up. The treatment compliance rate was 85.29% and the dropout rate was 14.71%. All the surgeries were successfully completed within 50–90 min, with an average of 69.9±8.9 min. The operation time of the first 29 patients was slightly longer, at 55–90 (74.8±8.4) min, and that of the subsequent 29 patients was 50–75 (65.0±6.4) min. The difference was statistically significant (P<0.05). Intraoperative blood loss was 5–15 ml (10.2±2.2). The postoperative complications (complication rate 5.17%) were 1 case of traumatic arthritis, 1 case of incision infection, and 1 case of temporary dorsal foot numbness, which gradually recovered. No other rejection reactions or Lisfranc fracture-dislocations recurrence occurred during the follow-up period.

All patients were followed up for more than 1 year, with an average of 16.9±3.0 months and completed X-ray imaging at 6, 12, and 24 weeks postoperatively. The treatment compliance rate was 85.3% and the dropout rate was 14.7%. The fracture lines in the midfoot were indistinct on X-ray images, with no tenderness or percussion pain in the foot. Patients were able to walk independently for more than 3 min continuously, meeting the criteria for bony clinical healing. The average time for healing was 12.8±3.0 weeks. VAS, AOFAS, and Tegner scores of 58 patients were significantly improved after surgery (P<0.01) (Figure 5). VAS, AOFAS, and Tegner scores were significantly improved after surgery (F=250.76, P<0.01, effect size=0.949), (F=1209.24, P<0.01, effect size=0.989), and (F=564.53, P<0.01, effect size=0.977). The changes in clinical scores were significantly greater than the minimal clinically important difference (MCID) of each score (VAS: 1, AOFAS: 18, Tegner score: 1) [21–23]. AOFAS scores of 45 patients were excellent, and 8 were good. The good rate was 91.4% (53/58). With the increase in follow-up time, AOFAS and Tegner scores increase significantly, and the differences at different time points were statistically significant (P<0.01), except for the 1-year postoperative and last follow-ups. Among the follow-up patients, 50 (86.2%) returned to sports, and the time of return to sports was 7.1±1.3 months (Table 2).

Discussion

LIMITATIONS:

This study met the required sample size but had some limitations, including its retrospective design, lacking a control group and long-term follow-up data, and all procedures being performed by a single experienced surgeon, limiting the generalizability of results. The use of InternalBrace fixation for treating Lisfranc injuries requires a learning curve, and its long-term efficacy should be validated by larger controlled studies with longer follow-up periods.

Conclusions

InternalBrace fixation is an effective treatment method for Lisfranc injury. It provides sufficient stability for Lisfranc joint and satisfactory function, which allows early rehabilitation, with a low incidence of surgical complications.