Treatment of Fractures of the Humeral Surgical Neck: MIROS Versus Intramedullary Nailing—A Retrospective Study

Abstract

This retrospective study compares the clinical outcomes of the Minimally Invasive Reduction and Osteosynthesis System (MIROS) and intramedullary nailing (IMN) in treating isolated surgical neck fractures of the humerus. A total of 42 patients were included, with 18 treated using MIROS and 24 with IMN. The primary outcomes assessed were the complication rates, functional recovery (DASH score), pain levels (VAS), and radiological healing. The MIROS group exhibited a higher complication rate (22.2% vs. 8.8%), with K-wire migration and superficial infections being the most frequent. Patients treated with MIROS reported lower postoperative pain (VAS 45 ± 25.7) compared to the IMN group (VAS 58.1 ± 12.5). Both groups demonstrated radiological healing within three months, but one MIROS patient required reoperation due to hardware failure. No significant differences were observed in the DASH scores between the groups. Our findings suggest that IMN is a preferable treatment option for younger patients with good bone quality, while MIROS may still be beneficial for elderly patients with significant comorbidities, albeit with a higher risk of complications. Future prospective studies are recommended to confirm these findings.

1. Introduction

Fractures of the surgical neck of the humerus are a common injury, particularly in older adults, with the incidence rising with age. This injury is especially prevalent in elderly women due to osteoporosis and the increased likelihood of low-energy falls [1,2,3]. These fractures present a clinical challenge due to the complex anatomy of the humerus and the reduced bone quality in elderly patients [4]. Although conservative treatments can be effective for minimally displaced fractures, surgical intervention is necessary for those that are unstable, displaced, or non-reducible [4,5,6]. Various surgical options exist, including intramedullary nailing (IMN), open reduction and internal fixation (ORIF), and the Minimally Invasive Reduction and Osteosynthesis System (MIROS). Each method has its advantages and is selected based on patient-specific factors such as age, bone quality, comorbidities, and functional requirements [7,8,9,10,11,12,13,14,15,16]. IMN is more invasive but provides better fracture stability, making it ideal for younger patients with healthier bones [4]. MIROS, while less invasive, is associated with a higher risk of complications, including infection and K-wire migration [17,18]. Recent studies highlight the benefits of IMN over ORIF in terms of reduced intraoperative bleeding, shorter surgical times, and fewer complications, such as implant failure and osteonecrosis [17]. This retrospective study aims to compare the clinical outcomes of MIROS and IMN for the treatment of humeral surgical neck fractures. By assessing the complications, functional outcomes, and union rates, the goal is to determine the optimal surgical approach for different patient populations, particularly whether MIROS offers comparable results to IMN in terms of stability and healing, aiming to clarify which treatment is optimal based on patient demographics and bone quality.

2. Methods

This retrospective cohort study was conducted at the A.O.U. Policlinico G. Martino in Messina, Italy, between 1 January 2014 and 1 June 2020. A total of 85 patients with proximal humerus fractures were initially considered. After applying the inclusion and exclusion criteria, 42 patients with isolated surgical neck fractures of the humerus were included in the final analysis. Patients were assigned either MIROS or IMN based on surgeon discretion, influenced by their age and fracture characteristics. Blinding was maintained for post-surgical evaluations by two independent surgeons. The inclusion criteria were patients over 18 years of age with closed, isolated fractures of the surgical neck of the humerus. Exclusion criteria included open fractures, prior humeral fractures, prosthetic replacement, neuropathies, lack of follow-up, and patient death. Patients were divided into two groups: 18 treated with MIROS (Group A) and 24 treated with intramedullary nailing (Group B) (

Table 1. Patients included in the study.

	Group A	Group B
Gender F/M	12/6	9/15
Average Age	73.17 ± 7.85	54.38 ± 20.79
Fractured Dominant Limb	34%	76%

). The choice of treatment was based on the surgeon’s clinical judgment, which considered the patient’s age, comorbidities, and fracture characteristics. MIROS was preferred for elderly patients with significant comorbidities, while IMN was typically selected for younger patients with better bone quality. The surgical techniques were standardized across surgeons. MIROS, a minimally invasive external fixation method using K-wires, was applied for Group A, while Group B underwent intramedullary nailing, providing internal stabilization of the fracture. Both procedures were conducted under general anesthesia (Figure 1). Clinical evaluations occurred at 15 days, 1 month, 3 months, 6 months, and 1 year post-surgery, with an average follow-up period of 43 months (range: 21–65 months). The primary outcomes assessed included pain (Visual Analog Scale, VAS), functional outcomes (Disabilities of the Arm, Shoulder, and Hand score, DASH), and radiological healing assessed through anteroposterior and lateral X-rays. Two independent orthopedic surgeons, uninvolved in the initial surgeries, re-evaluated the medical records and imaging for consistency (M.P. and G.G.). Complications such as infections, K-wire migration (in Group A), and avascular necrosis were recorded. The outpatient physiotherapy program was structured into three distinct intervals, with each interval consisting of 10 sessions, each lasting 25 min per day. The postoperative rehabilitation protocols varied between the MIROS and IMN groups, reflecting the differing stabilization techniques and patient profiles. In the MIROS group, pendulum exercises were initiated at an average of four days after surgery, allowing for early mobilization within a protected range. Passive-assisted exercises were introduced two weeks postoperatively, with a gradual increase in the passive range of motion based on the patient’s tolerance. Patients were advised to progressively engage in active-assisted exercises as healing progressed, with care taken to avoid strain on the fixation apparatus. The aim was to promote joint mobility without compromising fracture stability. In contrast, patients in the IMN group commenced passive protected area exercises as early as the first postoperative day. The limb was immobilized in a sling for two weeks to ensure proper healing and minimize movement. Following this initial immobilization period, between the third and fifth weeks, patients transitioned to a more comprehensive physiotherapy regimen that included both active and active-assisted exercises. Intensive strength and flexibility training began approximately three months after surgery, with the goal of restoring full functional capacity and range of motion in the affected arm. This structured and differentiated approach to physiotherapy ensured that both groups received rehabilitation tailored to their specific surgical interventions, optimizing the recovery outcomes.

A power analysis was conducted prior to the study to determine the appropriate sample size for the detection of a significant difference in complication rates and functional outcomes between the MIROS and IMN groups. Based on an expected effect size of 0.4, with power of 80% and an alpha level of 0.05, a minimum of 42 patients was required to achieve sufficient statistical power. This sample size allowed the study to detect meaningful differences between groups while minimizing the risk of Type II errors. Statistical analyses were conducted using SPSS (version 21). Continuous variables were expressed as the mean ± standard deviation, and Student’s t-test was used to compare the outcomes between the two groups. A p-value < 0.05 was considered statistically significant.

3. Results

A total of 42 patients with isolated surgical neck fractures of the humerus were included in this retrospective study. The patients were divided into two groups: 18 treated with MIROS (Group A) and 24 treated with intramedullary nailing (IMN, Group B). The demographic characteristics of both groups showed significant differences. The average age in Group A was 73 ± 8 years, while, in Group B, it was 54 ± 21 years. Group A had a higher proportion of female patients (66.7%) compared to Group B (37.5%). Additionally, 76% of the fractures in Group B involved the dominant limb, while only 34% of the fractures in Group A were on the dominant side (p < 0.05) (Table 1). The patient demographics in the MIROS and IMN groups reflected the distinct clinical decision-making processes. MIROS patients were, on average, older and had more comorbidities, aligning with its indication for those requiring a less invasive procedure. This decision-making strategy ensured that MIROS was employed where minimizing the surgical burden was paramount, while IMN provided superior stability for younger, healthier patients. In terms of clinical outcomes, all patients in Group B achieved radiological and clinical healing by the 3-month follow-up. In contrast, one patient in Group A required reoperation due to K-wire migration, which necessitated conversion to IMN. This patient achieved complete healing after the second surgery, with no further complications. The average time for the removal of the external MIROS fixation in Group A was 35 ± 6 days. The complication rates were higher in the MIROS group compared to the IMN group. In Group A, 22.2% of the patients experienced complications, while only 8.8% of the patients in Group B had complications. In Group A, two patients (11.1%) developed superficial infections, both successfully treated with antibiotics. One patient (5.5%) developed avascular necrosis (AVN) of the humeral head, which eventually required prosthetic replacement 24 months after the initial surgery. Additionally, one patient (5.5%) experienced K-wire migration, leading to reoperation with IMN. In Group B, only two patients (8.8%) developed superficial infections, which were treated conservatively with antibiotics. No instances of AVN or hardware failure were reported in Group B. Functional outcomes, as measured by the Disabilities of the Arm, Shoulder, and Hand (DASH) score, were similar between the two groups. Group A had an average DASH score of 47.8 ± 21, while Group B had an average score of 49 ± 11 (p > 0.05). However, there were significant differences in the pain levels between the two groups. Patients in Group A reported lower pain scores on the Visual Analog Scale (VAS), with an average score of 45 ± 25.7, compared to 58.1 ± 12.5 in Group B (p = 0.035) (

Table 2. Comparison of Clinical Outcomes.

	Group A	Group B	p-Value
Medium FU	51 M	37 M
DASH	47.78 ± 21.04	49.06 ± 10.95	0.799
VAS	45 ± 25.72	58.12 ± 12.49	0.035

). Radiological healing was assessed at the 3-month follow-up. In Group B, all patients demonstrated complete radiological healing by this time. In Group A, most patients achieved radiological healing, although one required reoperation due to MIROS failure. No significant differences were observed in the time to radiological healing between the two groups, with both achieving healing within the 3-month follow-up period. Overall, the results of this study indicate that while both MIROS and intramedullary nailing provide effective treatment for surgical neck fractures of the humerus, MIROS is associated with a higher rate of complications, including K-wire migration and avascular necrosis. Despite these complications, patients treated with MIROS reported lower postoperative pain compared to those treated with IMN. On the other hand, intramedullary nailing provided better fracture stability, particularly in younger patients with better bone quality, and had a lower overall complication rate. These findings suggest that IMN is the more reliable option for patients with good bone quality, while MIROS may still be suitable for elderly patients with significant comorbidities, provided that the higher complication risk is considered. Radiological healing was assessed at the 3-month follow-up. In Group B, all patients demonstrated complete radiological healing by this time. In Group A, most patients achieved radiological healing, although one required reoperation due to MIROS failure. No significant differences were observed in the time to radiological healing between the two groups, with both achieving healing within the 3-month follow-up period. Overall, the results of this study indicate that while both MIROS and intramedullary nailing provide effective treatment for surgical neck fractures of the humerus, MIROS is associated with a higher rate of complications, including K-wire migration and avascular necrosis. Despite these complications, patients treated with MIROS reported lower postoperative pain compared to those treated with IMN. On the other hand, intramedullary nailing provided better fracture stability, particularly in younger patients with better bone quality, and had a lower overall complication rate. These findings suggest that IMN is the more reliable option for patients with good bone quality, while MIROS may still be suitable for elderly patients with significant comorbidities, provided that the higher complication risk is considered.

4. Discussion

Fractures of the proximal humerus are prevalent, especially in elderly individuals, and surgical neck fractures are a particularly challenging subset due to the patient population often presenting with comorbidities and osteoporosis [4,5]. In this retrospective study, we compared two surgical treatments: MIROS and intramedullary nailing (IMN). Our findings indicate that while both systems can achieve acceptable outcomes, important differences exist, particularly in terms of the complication rates and functional recovery, which must guide clinical decision-making. The clear clinical decision-making criteria utilized in this study underscore the importance of individualized treatment. The decision to use MIROS was informed by factors such as the patient’s frailty and comorbidity profile, while IMN was employed where robust internal fixation was necessary. This reflects the evolving best practices in orthopedic surgery, where patient-specific factors increasingly dictate the choice of intervention Several studies support our finding that intramedullary nailing (IMN) provides better long-term fracture stability and a lower rate of complications compared to MIROS. In particular, IMN has been associated with a lower incidence of infection and K-wire migration, complications that were observed more frequently in the MIROS group in our study. These findings are consistent with the literature highlighting the superiority of IMN in terms of biomechanical stability and lower infection risks in percutaneous techniques [17,18,19,20,21,22,23,24,25,26]. MIROS, while offering certain advantages such as reduced surgical times and lower anesthesia-related risks, also presents disadvantages, most notably an increased risk of K-wire migration and superficial infections. In our study, MIROS patients exhibited a 22.2% complication rate, compared to just 8.8% in the IMN group. This higher complication rate aligns with the findings from other studies, where minimally invasive systems like MIROS are reported to have a higher risk of infection due to the nature of percutaneous fixation [22]. Additionally, K-wire migration and synthesis failure, as observed in one patient who required reoperation, are well-documented complications associated with MIROS and similar systems [18]. This particular complication resulted in the patient requiring conversion to IMN to achieve fracture stability and healing, thus emphasizing the risk of failure in some cases. The differences in the outcomes may also be attributable to the fact that MIROS is typically used for patients with more severe comorbidities. In our study, the average age of the patients in the MIROS group was significantly higher than that in the IMN group (73 ± 8 years vs. 54 ± 21 years), which may partly explain the increased complication rate. Age and comorbidities are known risk factors for surgical complications, and MIROS is often selected to minimize surgical trauma in these vulnerable patients. This is consistent with the existing literature, which supports the use of less invasive techniques like MIROS in elderly patients with comorbidities [25,27]. One of the key concerns in treating proximal humeral fractures is the impact of the bone quality, particularly in older adults with osteoporosis. Our results indicated that the MIROS group, consisting predominantly of older patients, demonstrated a higher rate of complications. Bone fragility in this age group can lead to a reduced healing capacity and a higher risk of failure with less stable fixation systems such as MIROS. Although both MIROS and IMN were able to achieve radiological healing within 3 months, the need for reoperation in the MIROS group suggests that intramedullary nailing might be the preferable choice for younger patients or those with good bone quality, while MIROS may remain an option for elderly patients with severe comorbidities who require a less invasive approach [25,27]. Interestingly, despite the higher complication rate, the patients in the MIROS group reported lower pain scores on the Visual Analog Scale (VAS) compared to the IMN group. MIROS, due to its minimally invasive nature, may offer better immediate postoperative comfort, which is reflected in the pain scores. However, this advantage may be outweighed by the higher risk of complications in the long term [25,27]. This finding suggests that while MIROS may provide short-term benefits in terms of pain management, these benefits must be weighed against the potential for complications that may require reoperation, as seen in one of the patients in our study. The functional outcomes, as assessed by the DASH score, were similar between the two groups. This indicates that both MIROS and IMN are capable of providing satisfactory long-term functional recovery in terms of upper extremity function. However, our study also demonstrated that IMN provided better overall stability, particularly in younger patients, where the bone quality is typically better. The absence of significant differences in the functional scores between the groups suggests that while MIROS may not offer superior functional recovery, it still provides adequate results, particularly in elderly patients, where reduced surgical trauma is critical. Despite the promising results for both surgical approaches, there are several limitations to this study that must be considered. First, the retrospective nature of the study limited the ability to fully control for confounding variables, such as the differences in bone quality between younger and older patients. Additionally, the relatively small sample size, particularly in the MIROS group, may affect the generalizability of the results. Further randomized, prospective studies with larger patient populations are needed to confirm these findings and establish more definitive recommendations for the use of MIROS versus IMN. Another limitation is the heterogeneity in patient selection, with the MIROS group consisting of significantly older patients with more comorbidities compared to the IMN group. While this reflects real-world clinical practice, where less invasive techniques are often chosen for older, sicker patients, it complicates direct comparisons between the two groups. Future studies should aim to stratify the patients more clearly based on their age, comorbidities, and fracture characteristics to provide more targeted recommendations. Although the sample size was small, the power analysis confirmed that the study had sufficient power to detect significant differences in key outcomes between the MIROS and IMN groups. Future studies with larger sample sizes are recommended to validate these findings and further refine the clinical decision-making criteria. In conclusion, this study demonstrates that while MIROS offers certain advantages, such as lower postoperative pain and reduced anesthetic risks, it is associated with higher complication rates compared to intramedullary nailing. IMN provides superior stability and lower complication rates, particularly in younger patients with better bone quality. Surgeons should carefully weigh the benefits of reduced invasiveness with MIROS against the higher risks of infection and reoperation. Based on the results of this study, we recommend intramedullary nailing as the primary treatment option for most patients with surgical neck fractures of the humerus, reserving MIROS for elderly patients with significant comorbidities who require a minimally invasive approach. Further research is needed to confirm these findings, with particular attention to stratifying the patient populations and evaluating the long-term outcomes in larger, prospective cohorts [25]. By better understanding the risks and benefits of these surgical techniques, we can improve the treatment strategies for proximal humeral fractures and optimize the outcomes for all patient groups.

5. Conclusions

In conclusion, this study highlights the differences between MIROS and intramedullary nailing (IMN) in treating surgical neck fractures of the humerus. While MIROS offers advantages such as reduced surgical times and lower anesthesia risks, it is associated with higher complication rates, including K-wire migration and infections. MIROS offers benefits in specific populations, such as elderly patients with comorbidities. Future prospective studies should aim to confirm these findings and better clarify the long-term outcomes for these treatment modalities. IMN provides greater stability and lower complication risks, making it the preferable choice, particularly for younger patients or those with good bone quality. Surgeons should carefully consider patient-specific factors, such as age and comorbidities, when choosing the optimal treatment approach for humeral fractures.