Comparison between open reduction and internal fixation and minimally invasive plate osteosynthesis for unstable proximal humerus fractures treated with locking plate and intramedullary allograft: a retrospective study

Abstract

Background

The aim of this study was to compare the functional and radiological outcomes between open reduction and internal fixation (ORIF) and minimally invasive plate osteosynthesis (MIPO) with locking plate (LP) and intramedullary graft (IMG) for treatment of unstable proximal humerus fractures (PHFs).

Methods

Forty-seven patients with PHFs were treated with ORIF and MIPO techniques in 25 and 22 cases, respectively, and evaluated retrospectively with a minimum follow-up of 12 months. Thirty-one fresh-frozen fibulae and 16 lyophilized tibiae allografts were used for augmentation. Radiological evaluation included the change in neck-shaft angle (NSA) and humeral head height (HHH). Functional outcomes were assessed using DASH and absolute Constant-Murley Score (CS^abs) with its derivatives: relative (CS^rel) and individual relative (CS^indiv).

Results

Mean follow-up period was 27.4 ± 16.2 months for ORIF and 29.6 ± 17.6 for MIPO group. Mean age was 60.5 ± 13.7 and 66.3 ± 11.7 years for ORIF and MIPO group, respectively. Functional outcomes showed insignificant difference between the groups: CS^abs of 57.3 ± 21.2 in ORIF and 52.4 ± 18.9 in MIPO group, (p = 0.409); CS^rel of 73 ± 24.1 in ORIF and 73.9 ± 23.4 in MIPO, (p = 0.897); CS^indiv of 69.6 ± 24.8 in ORIF and 64 ± 25.5 in MIPO, (p = 0.428); DASH of 14.8 ± 12.5 in ORIF and 18.7 ± 14.5 in MIPO, (p = 0.324). There were no significant differences in radiological outcomes between the two groups: decrease of NSA was 7.8° ± 9.4° in ORIF and 8.2° ± 15.6° in MIPO, (p = 0.922). Decrease of HHH was 0.6 mm ± 5.5 mm in ORIF and 1.4 mm ± 2.6 mm in MIPO, (p = 0.380). Surgical time was 165.8 ± 77.6 min for ORIF and 84.7 ± 38.1 min for MIPO, with significant difference between the groups (p < 0.001). Most common complication was AVN, occurring in five (20%) and 8 (36%) patients in ORIF and MIPO groups, respectively.

Conclusions

The study found that using LP fixation and IMG augmentation to treat unstable PHFs resulted in similar functional and radiological outcomes between the ORIF and MIPO techniques. However, the MIPO technique had a significantly shorter surgical time compared to ORIF.

Trial registration

The study was conducted in line with the principles of the Declaration of Helsinki as well as national legal and regulatory requirements. The trial was retrospectively registered and approval was granted by the local Ethics Committee of University Multiprofile Hospital for Active Treatment and Emergency Medicine “N. I. Pirogov”, Sofia, Bulgaria: (No. EC – 01/26.01.2023).

Introduction

Proximal humerus fractures (PHFs) represent 53% of all shoulder girdle injuries [1]. In patients older than 65 years their incidence is ranked third, following distal radius and femoral neck fractures [2–4]. Although only 20% of these fractures are unstable and require surgical treatment [5], the expected increase in their incidence by year 2030 will result in a higher number of corresponding surgical procedures [3, 6]. Among the variety of existing fixation methods, locking plate (LP) fixation has become the gold standard for treatment of unstable PHFs [7]. However, locked plating is still associated with a high rate of complications and reoperations, mostly due to varus collapse, screw penetration in the glenohumeral joint and avascular necrosis (AVN) of the humeral head [8, 9]. Most authors suggest that these complications are related to fracture type and morphology (three- and four-part fractures according to Neer classification, [5] additional medial comminution [10], osteoporosis [11], initial varus displacement [12, 13] and indicators for ischemic changes [14]), inability to obtain anatomical or nearly anatomical reduction [15, 16] and LP rigidity [9, 11].

The intramedullary graft (IMG) is able to recreate the missing medial support by filling in the osteoporotic defect and withstanding the deforming forces of the rotator cuff [17]. In a pilot study, Gardner et al. [17] enhanced the stability of LP constructs by adding intramedullary fibular allograft in seven cases of unstable PHFs with medial calcar deficiency and/or osteoporosis, demonstrating no complications. Their promising results have leveraged the interest towards biomechanical [18–22] and clinical studies [23–36] focusing on the treatment of unstable PHFs with simultaneous application of locked plating and intramedullary grafting. While most of these authors use open reduction and internal fixation (ORIF), there is still a lack of reports focusing on fixation of unstable PHFs with LP and IMG using the minimally invasive plate osteosynthesis (MIPO) technique. Furthermore, to our knowledge, there is no study comparing the two techniques (ORIF vs. MIPO) in the presence of allograft augmentation.

Therefore, the aim of this study was to compare the functional and radiological outcomes between ORIF and MIPO with locking plate and intramedullary graft for the treatment of unstable proximal humerus fractures.

Patients and methods

Institutional review board approval was granted by the local ethics committee for this retrospective study on patients with unstable PHFs. All patients were treated surgically with simultaneous locked plating and intramedullary grafting at our level 1 trauma center from January 2015 until November 2020. The inclusion criteria considered: (1) patients aged 18 years or older, (2) patients with non-pathological and unstable fracture according to the Neer criteria [5] (displacement of more than 1 cm and/or angulation of more than 45°), (3) with fractures having additional features of instability and complexity such as medial comminution, osteoporosis and/or initial varus displacement, (4) patients without history of a recent trauma to the contralateral shoulder, (5) time to surgery within 3 weeks. Exclusion criteria were: (1) patients under the age of 18 years, (2) patients with impaired shoulder function prior to the traumatic incident, (3) patients with pathological fractures, (4) open fractures, (5) fractures with more than 3 weeks between injury and surgery.

Results

114 patients were treated surgically with simultaneous locked plating and intramedullary grafting from January 2015 to November 2020. Sixteen patients died from causes unrelated to surgery. Three patients did not meet the inclusion criteria. We were able to establish contact with 76 of the remaining 95 patients. Twenty-nine of them didn’t comply with visiting the hospital for a follow-up evaluation, mostly because of their advanced age and health concerns due to the Covid-19 pandemic. As a result 47 patients were retrospectively evaluated and appeared for final follow-up of a minimum of 12 months post surgery. The majority of them were female (79%). The patients’ age was 60.5 ± 13.7 years on average (mean value ± SD, range 33–81 years) in the ORIF group and 66.3 ± 11.7 (range 34–84 years) in the MIPO group. The follow-up period among all patients was 28 ± 17.2 months (range 12–79 months) with 27.4 ± 16.2 months (range 12–79 months) for the ORIF and 29.6 ± 17.6 months (range 12–72 months) for the MIPO group. Patient, fracture, and surgical technique characteristics for both groups are detailed in (Table 1).

.

The objective functional outcomes for both study groups were satisfactory in terms of: (1) CS^abs with 57.3 ± 21.2 in the ORIF and 52.4 ± 18.9 points in the MIPO group, (2) good in terms of CS^rel with 73.0 ± 24.1 in the ORIF and 73.9 ± 23.4 in the MIPO group, (3) good in terms of CS^indiv with 69.6 ± 24.8 in the ORIF and 64.0 ± 25.5 in the MIPO group. There were no significant differences between the two groups in terms of CS^abs (p = 0.409), CS^rel (p = 0.897) and CS^indiv (p = 0.428). The DASH score was 14.8 ± 12.5 in the ORIF and 18.7 ± 14.5 in the MIPO group, with no significant difference between the two groups (p = 0.324)

With a mean intraoperative NSA of 136.4° ± 13.3° and an NSA at the final follow-up of 128.6° ± 13.1°, the decrease of NSA in the ORIF group was 7.8° ± 9.4°. The mean intraoperative NSA for the MIPO group was 126.7° ± 15.9° and the NSA at final follow-up was 118.5° ± 20.2° and the decrease of NSA was 8.2° ± 15.6°. The decrease of HHH for the ORIF group was 0.6 mm ± 5.5 mm, with intraoperative HHH of 13.5 ± 3.3 mm and HHH at the final-follow up of 12.9 ± 4.1 mm. The decrease of HHH in the MIPO group was 1.4 mm ± 2.6 mm, with an intraoperative HHH of 14.7 mm ± 4.9 mm and a HHH at final-follow up of 13.3 ± 5.8 mm. There were no significant differences between the two study groups in terms of decrease of NSA (p = 0.922) and HHH (p = 0.380).

From a clinical perspective, the most significant difference was found in the duration of the surgical procedure, which was almost twice shorter for MIPO with 84.7 min ± 38.1 min versus ORIF with 165.8 min ± 77.6 min, p < 0.001.

The main clinical outcomes and complications are summarized in Table 2.

There were 25 complications in 16 patients in the ORIF group and 25 complications in 11 patients from the MIPO group. The most common clinically relevant complication was AVN of the humeral head, occurring in 5 (20%) and in 8 (36%) of the cases in the ORIF and MIPO groups, respectively. Secondary varus displacement with a decrease in NSA of more than 10° was detected in 10 (40%) of the patients in the ORIF group and 7 (32%) patients in the MIPO group. One (4%) patient in the ORIF group and five (23%) in the MIPO group had a final NSA of less than 110°. Secondary screw penetration through the humeral head was observed in 7 (28%) patients in the ORIF and in 7 (32%) of the patients in the MIPO group. Secondary screw penetration was due to secondary varus displacement in one (5%) patient in the MIPO group and two (8%) in the ORIF group, and due to AVN of the humeral head in 6 (27%) in the MIPO group and 5 (20%) patients in the ORIF group. No primary screw penetrations were observed in either group. Subacromial impingement (SAI) was diagnosed in 2 (8%) of the patients in the ORIF and in 3 (14%) in the MIPO group. In four of the five cases, it developed because of displacement and proximalization of the greater tuberosity (GT) and in one case in the ORIF group, the cause was secondary varus displacement. In the ORIF and MIPO groups, arthritic changes of the glenohumeral joint due to AVN of the humeral head occurred in 3 (12%) and 1 (5%) cases, respectively. In 7 (28%) cases in the ORIF and 1 (5%) case in the MIPO group, AVN of the GT was diagnosed.

No nonunions, superficial and deep infections or axillary nerve damage were observed in either group. Secondary surgical procedures were performed in 6 (12.8%) of all patients. Five of the procedures necessitated hardware removal due to AVN and secondary screw penetration – in one (4%) patient in the ORIF and 4 (18%) in the MIPO group. One patient in the MIPO group underwent arthroplasty after developing AVN and secondary screw penetration. No significant differences were found between the two groups in terms of complications and reoperation rate.

Discussion

The main finding of the present study is that MIPO using locking plate supplemented with intramedullary graft is associated with a significantly shorter operative time compared to ORIF. However the functional and radiological outcomes as well as complication rate were comparable for both surgical methods.

Open reduction with internal fixation via the conventional deltopectoral approach is the most commonly used fixation technique for unstable PHFs [7, 38, 41]. The advantages of ORIF include an excellent visibility of the anterior aspect of the proximal humerus, ease in applying the LP, valuable options for extension of the exposure both distally and proximally and reduced risk of neurovascular injuries [7, 41]. On the other hand the disadvantages of open plating are related to the inevitable soft tissue stripping, the significant risk of AVN (due to damage to the ascending branch of the anterior circumflex artery) and the limited exposure of the lateral aspect of the proximal humerus [41, 42]. The MIPO technique with the deltoid splitting approach requires less soft tissue stripping and has a lower risk of injury to the anterior circumflex humeral artery, resulting in a lower rate of AVN [41, 42, 43]. The MIPO technique provides direct access to the lateral aspect of the proximal humerus, but the procedure could be technically challenging as fragments need to be reduced indirectly, especially in the medial part of the proximal humerus [41]. Another disadvantage of the technique is the possible risk of axillary nerve damage [7, 41, 43]. Regardless of the method used, LP fixation in unstable PHFs is still associated with high complication rate [44].

The use of IMG as augmentation to the LP fixation was introduced by Garder et al. in order to reduce the number of complications [17]. Biomechanical studies conclude that IMG increases stiffness and failure load of the bone-implant constructs, and limits fracture displacement, [18–22] while simultaneously allowing interfragmentary micro-movements [18, 45]. This additional rather elastic stabilization meets Lill's criteria for setting of an ideal fixation device for PHFs [46]. Overall, the available clinical studies demonstrate good or excellent functional results with a small percentage of complication when using IMG with LP for unstable PHFs [23–36].

From the available literature, most authors use ORIF when using LP and IMG fixation for unstable PHFs [23–29, 31–36] and only one author uses MIPO technique with the deltoid splitting approach [30]. To our knowledge, the current study is the first comparing ORIF and MIPO techniques in the presence of LP fixation with IMG. In a prospective, randomized controlled trial, Sohn et al. compared the two fixation techniques in unstable PHFs and found no statistically significant differences in terms of functional and radiological outcomes, but the MIPO technique provided significantly shorter operation time than open plating [41]. Another prospective, randomized study by Bhayana et al. comparing the two surgical approaches came to a similar conclusion [43]. The results of the present study further support these findings, which are also relevant in the presence of IMG augmentation. Although functional and radiological outcomes do not appear to differ significantly, a shorter duration of surgery may be beneficial for patients who have serious comorbidities or multiple fractures due to trauma [41]. One disadvantage of the MIPO technique is believed to be the potential damage of the axillary nerve which invariably lies over the holes through which the calcar screws have to be inserted [43]. LP fixation with IMG through MIPO has an additional benefit of providing robust cortical support using the intramedullary graft which has been proven to eliminate the need for calcar screws [45, 47]. The suggestion that fracture reduction with the MIPO technique is technically demanding may be supported by our results, showing that anatomical reduction is significantly more prevalent in the ORIF group. However, the latter did not seem to affect the final functional outcomes between the two groups in the current study.

The functional outcomes for the both group of the current investigation are comparable with the reported values in the literature on LP fixation with IMG in terms of DASH score [23–26, 29, 33], CS^indiv and CS^rel [23–26, 29, 31, 32, 36]. In addition, the change in HHH for both groups is within the reported range from 0.3 mm to 2.14 mm [24, 26–28, 31, 32], being less than the critical level of 5 mm. In the literature, the critical change of NSA varies between 5° and 10° [28, 30, 48, 49] and some authors report values between 2.6° and 3.25° [28, 30–32, 34, 36] which are superior to our findings. However, although the change in NSA reflects the loss of reduction, it’s not the most accurate criterion for a varus deformation, as some patients have such a change of more than 10° but still have NSA within physiological borders (120°-150°). We support the conclusion of Shnetzke et al.[15] that NSA between 110° and 120° still represent an acceptable varus deformation, while values below 110° are considered a real varus deformation.

The rate of AVN in the previous investigations of PHFs fixed with IMG and LP varies from 0–10.6% [17, 23–29, 31, 32], which is less than the rates reported in the current study. Besides, secondary screw penetration through the humeral head was much higher versus the previous reports (0–4%) [17, 24, 28, 31]. Another complication identified in this study and not reported in previous work on PHFs treated with LP and IMG, was SAI and AVN of the GT. We were not able to establish the cause for AVN of GT. One reason might be the potential injury of the anterior circumflex vessels due to the deltopectoral approach used in 7 of 8 patients. [46] The other potential cause might be the allograft itself as Miyamura et al. [50] pointed out that fibular cortical strut may interfere with revascularization, resulting in tuberosity resorption. In all 8 patients with AVN of the GT a fresh frozen fibular allograft was used. The complication was diagnosed on the final follow-up x-rays, but the shoulder function was seriously altered in only 2 of the patients.

Although the current study showed higher complication rate compared with the previous reports, there were no significant differences between the ORIF and MIPO groups in terms of functional and radiological outcomes as well as complications rate.

Our study has some limitations. First, the study was limited by its retrospective design, which could introduce selection bias and the potential for confounding. Second, the sample size is relatively small and futher studies with a bigger sample size are therefore required to confirm these results. Third, the number of surgeons performing the procedure could be a source for a potential bias, influencing the external validity of the study. However, all surgeons are from the same department, they all had more than ten years of experience in the management of proximal humerus fractures before the beginning of this study and the surgical technique did not involve a long learning curve. Fourth, the duration of follow-up is also relatively short. The minimum follow-up period was 12 months, which may not be sufficient to identify all negative clinical outcomes after osteosynthesis of proximal humeral fractures. However, the mean duration of follow-up in our study was 28 months, which is similar to that reported in the literature.

Conclusion

The study found that using LP fixation and IMG augmentation to treat unstable PHFs resulted in similar functional and radiological outcomes between the ORIF and MIPO techniques. However, the MIPO technique had a significantly shorter surgical time compared to ORIF.

Abbreviations

Declarations

Acknowledgements:

Not applicable.

Authors’contributions

The authors’ contributions to this study were as follows. L.R. wrote the manuscript. L.R., A.B., M.R., D.E. contributed to the study design. L.R. and M.H. contributed to the data collection. K.P. contributed to the statistical analysis. B.G., M.R. and V.R. revised the manuscript. All authors discussed the results and contributed to the final manuscript. All authors read and approved the submitted version of the manuscript.

Funding

Open access funding provided by University Multiprofile Hospital for Active Treatment and Emergency Medicine “N. I. Pirogov”, Sofia, Bulgaria.

Availability of data and materials

The datasets used during the current study are available from the corresponding author on reasonable request.

Declarations

Ethics approval and consent to participate

The study was conducted in line with the principles of the Declaration of Helsinki as well as national legal and regulatory requirements. The trial was retrospectively registered and approval was granted by the local Ethics Committee of University Multiprofile Hospital for Active Treatment and Emergency Medicine “N. I. Pirogov”, Sofia, Bulgaria: (No. EC – 01/26.01.2023).

Consent for publication

Not applicable.

Competing Interests

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

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