Pin fixation is an effective method for fixation of bunion osteotomy with various procedures: a retrospective cohort study

Abstract

Background

Various fixation devices are available for bunion osteotomy. In this study, we evaluated the radiographic outcomes, postoperative complications, and recurrence rate in a series of hallux valgus deformities treated with various osteotomy procedures using a pin for the fixation of the osteotomy.

Methods

Two-hundred forty-seven patients with hallux valgus deformity managed with a Simple, Effective, Rapid and Inexpensive (SERI) osteotomy, distal chevron osteotomy, or proximal crescentic osteotomy and K-wire fixation were included. The mean follow-up of the patients was 53.9 ± 8.9 months. Radiographic evaluations included the assessment of the Hallux valgus angle (HVA), intermetatarsal angle (IMA), and union. Clinical evaluations included the assessment of the range of motion, pain in the first metatarsophalangeal joint, and patient satisfaction.

Results

In the last visit, the mean improvement of HVA was 23.9 ± 9.1º (P < 0.001). The mean IMA improvement was 6.1 ± 6º (P < 0.001). The mean metatarsophalangeal flexion and extension were 33 ± 10.7º and 34.6 ± 9.2º, respectively. Postoperative complications included pin tract infection in eight (3.2%) patients, deep infection in five (2%) patients, and early pin complication in four (1.6%) patients. Recurrence was observed in five (2%) patients. Twenty-three (9.3%) patients had slight pain in the last follow-up. The mean surgical time was smaller in the SERI osteotomy (P < 0.001). The mean hospitalization period was longer in the proximal osteotomy group (P = 0.039). The mean metatarsophalangeal flexion and extension were significantly smaller in the distal chevron osteotomy (P = 0.046 and P = 0.037, respectively). 90% of patients were satisfied or very satisfied with the surgical outcomes.

Conclusion

K-wire fixation is a safe and effective device for the fixation of bunion osteotomy, and this effectiveness is even higher with SERI and proximal crescentic osteotomy.

Introduction

Hallux valgus deformity, also known as a bunion, is a common forefoot disorder caused by the subluxation of the first metatarsophalangeal joint, leading to the internal deviation of the first metatarsal and external deviation of the great toe, creating a medially prominent first metatarsal head [1]. The prevalence of hallux valgus deformity is estimated at around 23% between the age of 18 to 65 years and 35.7% in adults aged over 65 years [2]. This condition can result in painful movements and difficulty in wearing shoes [1]. Although the exact etiology of hallux valgus is not clear, an imbalance in the abductor and adductor muscles, genetic susceptibility, and constricting footwear are noted to contribute to the formation of this deformity [3].

The primary aims of treatment for hallux valgus are pain relief and restoration of the function of the first metatarsophalangeal joint [4, 5]. More than 150 different surgical techniques have been introduced for bunion, of which osteotomy is considered the main surgical treatment. A variety of osteotomy procedures has been described for hallux valgus, including the SERI (Simple, Effective, Rapid, and Inexpensive) osteotomy, distal chevron osteotomy, and proximal osteotomy [6]. Even so, many patients avoid surgical treatment because of the fear of surgical complications and low patient satisfaction rates reported for various surgical techniques [7,8,9,10].

Various fixation methods are available for bunion osteotomy, with their own advantages and disadvantages. Plates and screws provide a strong fixation, but the non-anatomic placement of these devices may cause loss of correction and deformity relapse [11]. In addition, hardware irritation might lead to early device extraction [12]. Kirschner-wire (K-wire) fixation is technically feasible, less expensive in comparison to plate and screw, and less prone to cause hardware irritation. However, the fixation stability of pin fixation is smaller than plate and screw, which increases the risk of pin loosening and migration, leading to fixation failure and correction loss [11]. Although a greater rate of deformity recurrence has been reported using a plate and screws versus pin fixation of bunion osteotomy, the number of studies reporting the outcomes of pin fixation in this setting is limited [5]. In this study, we aimed to evaluate the clinical and radiographic outcomes and postoperative complications in a series of patients with hallux deformity treated with various osteotomy procedures and pin fixation. We hypothesized that if pin fixation provides a stable bunion osteotomy, it can be selected as the fixation device of choice, considering its lower costs.

Methods

This cohort study was approved by the ethics board of our institute under the code IR.IUMS.REC.1399.923 Medical profiles of the patients who underwent bunion osteotomy in our university hospital between 2011 and 2019 were retrospectively reviewed. Inclusion criteria were treatment with the SERI osteotomy, distal chevron osteotomy, or proximal crescentic osteotomy, pin fixation, and a minimum follow-up of 12 months. Patients with severe stiffness in 1st MTP joint and patients who had a history of surgical treatment for their current problem were excluded from the study. Surgical indications were a hallux valgus angle of > 15º, pain, walking problem, and restricted movement of range in the first metatarsophalangeal joint. Two hundred and forty-seven patients were included in the final analysis.

Surgical technique

All the surgeries were done by one senior orthopedic surgeon in the same center. For patients with subluxation of the first metatarsophalangeal joint, a Modified McBride’s bunionectomy was implemented before the osteotomy [13]. Then, Simple, Effective, Rapid and Inexpensive (SERI) osteotomy (n = 76) [14], distal chevron osteotomy (n = 69) [15], or proximal crescentic osteotomy (n = 102) [16] were done as previously described. For the SERI osteotomy, a transverse extracapsular osteotomy was done through a 1-cm incision made from the proximal to the extracapsular first metatarsophalangeal joint. Then, a 2.5-mm extramedullary pin from the medial portion of bone from the tip of the big toe proceeded to the osteotomy place and lateralize the distal fragment, and went to the medulla of the proximal fragment of the osteotomy and proceeded up to the medial cuneiform (Fig. 1). The pin entered the medial side of the base of the proximal phalanx and then passed across the metatarsophalangeal joint into the medial side of the first metatarsal head.

Fig. 1

Preoperative (a), early postoperative (b), and late postoperative (c) anteroposterior radiograph of a hallux valgus lesion treated by SERI osteotomy

For the distal chevron osteotomy, a medial approach was used, and osteotomy was done 1 cm proximal to the metatarsophalangeal joint, with an angle of 100º between the two osteotomy arms (modified chevron osteotomy), and after correction, fixed with two 1.5-mm pins crosswise from the proximal to the distal (Fig. 2).

Fig. 2

Preoperative (a), early postoperative (b), and late postoperative (c) anteroposterior radiograph of a hallux valgus lesion treated by distal chevron osteotomy

For the proximal osteotomy, through a dorsal approach, a 5 cm dorsal incision was made from 1 cm proximal to the first tarsometatarsal joint to the 4 cm distal to the first tarsometatarsal joint. After that, a crescentic (dome) osteotomy was done 1 cm distal to the tarsometatarsal joint and, after correction, cross-fixed with two 1.5-mm pins (Fig. 3).

Fig. 3

Preoperative (a), early postoperative (b), and late postoperative (c) anteroposterior radiograph of a hallux valgus lesion treated by proximal osteotomy

Postoperative protocol

After the operation, the foot was immobilized in a short leg splint for six weeks. The patients remained on partial weight-bearing during this period. Full-weight-bearing was started after six weeks. Sutures were pulled two weeks after the operation, and intermittent ankle movements were started at the same time. If signs of radiographic consolidation were observed within six weeks, the pin was removed. Weight-bearing was allowed after pin removal.

Evaluations

Anteroposterior and lateral weight-bearing radiographs were obtained before the operation, at the first postoperative visit (two weeks after the operation), and at the last follow-up visit. Radiographic evaluations included assessment of the Hallux valgus angle (HVA), intermetatarsal angle (IMA), union, sterile pin tract formation, osteolysis, and/or fixation failure. Enlargement of the pin tract was regarded as a sign of osteolysis. Clinical evaluations included the assessment of the range of motion (ROM) for the first metatarsophalangeal joint and pain by the Visual Analogue Scale (VAS). The patient’s satisfaction was rated using a 0–5 points Likert scale, in which 0 was indicative of extremely unsatisfied and 5 was indicative of extremely satisfied. Postoperative complications, including the recurrence of deformity, wound infection, pin breakage, or loosening, were extracted from the medical profiles of the patient.

Sample size statistical analysis

Considering a 0.8% deep infection rate after the osteotomy for correction of hallux valgus [17], error size of 5%, and a confidence interval of 95%, the sample size of 13 patients was estimated to be enough for this cohort study. However, we included all the patients who were referred during the study period to improve the power of the study.

SPSS for Windows, Version 16 (SPSS Inc., Chicago, Ill., USA) was used for the statistical analyses of data. Descriptive information was demonstrated with mean ± standard deviation (SD) or numbers with percentages. A paired t-test was used to compare the mean preoperative and postoperative measures. An Analysis of Variance (ANOVA) test was used to compare the mean values between the three groups. Qualitative variables were compared with a chi-squared or Fisher’s exact test. A P-value < 0.05 was considered statistically significant.

Results

The study population included 201 (81.4%) females and 46 (18.6%) males with a total mean age of 48.3 ± 16 years. The mean follow-up period of the study was 53.9 ± 8.9 months. Characteristic features of the patients are demonstrated in Table 1.

Table 1 Characteristic features of the patients who underwent bunion osteotomy and pin fixation

The surgical duration was 38.4 ± 8.1 min on average. The mean hospitalization period was 1.5 ± 1 days. The mean improvement of HVA in the last follow-up visit was 23.9 ± 9.1º (P < 0.001). The mean IMA improvement in the last follow-up visit was 6.1 ± 6º (P < 0.001). The mean metatarsophalangeal flexion and extension were 33 ± 10.7º and 34.6 ± 9.2º, respectively.

Union at the osteotomy site was observed in all patients. Pin tract infection was recorded in eight (3.2%) patients and managed with oral and topical antibiotics. Deep infection occurred in five (2%) patients, which was managed with hospitalization and wound irrigation, and intravenous antibiotics. Four (1.6%) patients had early pin complications, including pin breakage (n = 1), loosening (n = 2), or migration (n = 1). No intervention was done for these patients because a complication occurred for one of the pins in the distal chevron osteotomy or proximal crescentic osteotomy, and the osteotomy alignment was not disrupted. Recurrence of bunion was observed in five (2%) patients and was managed with reoperation. Twenty-three (9.3%) patients had remaining pain in the last follow-up. The mean VAS for pain was 2.1 ± 1.2 in these patients. 90% of patients (n = 222) were satisfied or very satisfied with the surgical outcomes. The outcomes of interest have been summarized in Table 2. No case of metatarsalgia was observed in patients undergoing proximal crescent osteotomy.

Table 2 Outcomes of the patients who underwent bunion osteotomy and pin fixation

Comparison of the three osteotomy procedures

No significant difference was observed between the demographic characteristics of the three osteotomy groups (Table 3).

Table 3 Characteristic features of the patients who underwent bunion osteotomy with various procedures

The mean surgical time was significantly smaller in patients who underwent SERI osteotomy (P < 0.001). The mean hospitalization period was significantly higher in the proximal osteotomy group (P = 0.039). The mean metatarsophalangeal flexion and extension were significantly smaller in the distal chevron osteotomy (P = 0.046 and P = 0.037, respectively). The mean improvement of HVA was 24.3 ± 12.7º in the proximal osteotomy groups, 23.1 ± 13.5º in the distal osteotomy group, and 24.5 ± 11.1º in the SERI osteotomy group. This difference was not statistically significant (P = 0.75). The mean improvement of IMA was 6.1 ± 6.2º in the proximal osteotomy groups, 5.8 ± 5.5º in the distal osteotomy group, and 5.8 ± 5.7º in the SERI osteotomy group. This difference was not statistically significant (P = 0.95). No other significant difference was also observed between the three osteotomy groups (Table 4).

Table 4 Comparison of outcomes between the three osteotomy procedures

Discussion

In this study, we evaluated the outcomes of bunion osteotomy and pin fixation with three different procedures. Union of osteotomy was observed in all patients. Pin-related complications, including infection, breakage, or lessening, were observed in 12 (4.8%) patients, none of which required reoperation. Only five (2%) recurrences were observed in the present series. The HVA and IMA were significantly improved immediately after the operation, and this improvement was preserved until the last follow-up (mean follow-up of 53.9 months). Metatarsophalangeal ROM was acceptable. Twenty-three patients had slight pain in the last follow-up. 90% of patients were satisfied or very satisfied with the surgical outcomes. A comparison of three osteotomy procedures showed lower surgical duration with SERI osteotomy, longer hospitalization with proximal crescentic osteotomy, and smaller radiographic improvement and ROM with distal chevron osteotomy.

Mancuso et al. reported the outcomes of distal metatarsal osteotomy with smooth K-wire fixation in 500 patients over a 10-year period. Their complications included eight malunions, one delayed union, and two cases of aseptic necrosis. Fifty-four patients (10.8%) experienced pin irritation. Seven infections (1.4%) occurred in their series. The effectiveness of K-wire was lower in certain osteotomy procedures, such as the Laird osteotomy, while others, such as the Chevron osteotomy, had smaller complications. Due to the small number of complications and the high success rate, the authors concluded that K-wire is a viable option for the fixation of distal metaphyseal osteotomy [18]. In the present study, we observed no case of mal-union, delayed union, or nonunion. Similar to the study of Mancuso et al., the number of complications was small with k-wire fixation. In addition, our results showed inferior outcomes of distal chevron osteotomy compared to the proximal or SERI osteotomy. Therefore, our results confirm the effectiveness of k-wire fixation in the bunion osteotomy and show that effectiveness could be further improved if SERI and proximal osteotomy are used instead of the distal chevron osteotomy.

Baig et al. prospectively evaluated the outcomes of distal chevron osteotomies with K-wire fixation in the treatment of 20 patients with hallux valgus deformity. One year after the operation, the mean American Orthopedic Foot and Ankle Score (AOFAS) of the patients improved from 51 to 82. The mean HVA improved from 26° to 14°. Five (25%) postoperative complications included one case of postoperative pain and four cases of K-wire complications, including two K-wire migrations and two pin site infections. They concluded that K-wire fixation has a relatively high rate of complication and planned to use other fixation methods [19]. The rate of postoperative complications was 4.8% in the present study, which was remarkably smaller than the study of Baig et al. Therefore, our study does not support the conclusion reported by Baig et al.

Rogero et al. reported the outcomes of K-wire Fixation following the distal chevron osteotomy for the correction of hallux valgus deformity in 223 patients. K-wires were removed two weeks after the operation. At a mean follow-up of 24.6 months, the mean IMA of the patients improved from 11.4º to 4.6º. The tibial sesamoid position decreased from 4.6 preoperatively to 2.6 at the final follow-up. They concluded that early wire removal is safe and effective while it reduces the rate of postoperative complications, such as pin tract infection and bending or breakage of the K-wire [20]. In the present study, we removed pins six weeks after the operation. Although our complication rate was acceptable, the study of Rogero et al. revealed that the complication rate could be further reduced if the pins were removed earlier than six weeks.

Park et al. compared the results of K-wires and locking plates for the fixation of proximal chevron osteotomy in the treatment of hallux valgus deformity. In the last follow-up, the mean AOFAS was not significantly different between the two groups. However, mean HVA and metatarsal distance were significantly larger in the plate fixation group. The recurrence rate was 9.8% in the K-wire group and 33.3% in the plate group [11]. The recurrence rate was 1.9% in the proximal osteotomy group of the present study. Although we did not compare the results of k-wire with plate fixation, such a low rate of recurrence could support the effectiveness of k-wire fixation in bunion osteotomy.

Jung et al. compared the outcomes of pin-only fixation with a combined pin and screw fixation of proximal chevron osteotomy for the correction of hallux valgus deformity. The mean VAS for pain decreased from 6.3 to 1.6 in the K-wire group and from 5.7 to 0.5 in the combined group. The mean AOFAS improved from 59.4 to 88.9 in the K-wire group and from 58.2 to 95.3 in the combined group. The satisfaction rate was 85% in the K-wire group and 93% in the combined group. The mean improvement of HVA and IMA was also significantly greater in the combined group [21]. In the present study, we did not evaluate the outcomes of combined pin and screw fixation.

Winemaker et al. compared the results of bioabsorbable pins and K-wires in the fixation of chevron osteotomies for the correction of Hallux deformity. At an average follow-up of 35.6 months for the K-wire group and 23.1 months for the absorbable pin group, clinical follow-up scores, postoperative HVA, and IMA were similar in both groups. No complication was recorded in the absorbable pin group. In the K-wire group, two patients had a malunited osteotomy, and two patients had a retained K-wire at the final follow-up. They concluded that bioabsorbable pins are as effective as K-wires in the fixation of bunion osteotomy [22]. Although bioabsorbable pins might be a viable alternative for K-wire fixation, higher costs of bioabsorbable pins are a concern, particularly in developing countries.

We postoperatively immobilized the foot in a splint for six weeks, which may seem too long for a procedure often managed with immediate weight bearing in flat shoes. This extended period might raise concerns about potential complications like complex regional pain syndrome (CRPS) [23]. However, in our country, flat shoes aren’t covered by insurance, leaving us no option but to opt for six weeks of non-weight bearing. Despite this, we initiated intermittent ankle movements two weeks post-surgery to mitigate the risk of CRPS.

Altogether, the results of the present study, along with the results of earlier studies, reveal the effectiveness of K-wire for the fixation of bunion osteotomies. However, the present study was not without limitations. The main limitation of the study was its retrospective design, which did not allow evaluation of clinical scores in the present series, as preoperative scores were not available. The absence of a control group fixed with other devices, such as the plate or screw, could be regarded as the other limitation of the study. Therefore, future complementary studies resolving these limitations are required.

Conclusion

K-wire fixation of bunion osteotomy results in significant improvement in radiographic measures. Also, the rate of postoperative complications and recurrence was considerably low following bunion osteotomy and K-wire fixation. Therefore, K-wire fixation could be regarded as an effective device for the fixation of bunion osteotomy.