Abstract
Introduction
Plate osteosynthesis is preferred for the treatment of proximal humerus fractures (PHFs). However, applying the locking plate flush against the bone may lead to varus malreduction and medial displacement of the humeral head. We hypothesized that slight valgus reduction and valgus bent locking plate fixation against potential varus deformation would yield better results than the traditional plate fixation.
Methods
We retrospectively reviewed patients with PHFs treated with locking plate fixation between March 2014 and July 2019. We evaluated changes in the neck–shaft angle (NSA) and humeral head height, as well as the development of complications postoperatively. Clinical outcomes were measured at 1-year post-surgery and at the last follow-up using the American Shoulder and Elbow Surgeons, the Disabilities of the Arm, Shoulder and Hand, and the Constant–Murley scores.
Results
A total of 58 patients with PHFs were enrolled in this study. They were divided into the valgus-aligned group (n = 28) and the anatomical group (n = 30). According to radiographic evaluation, immediate postoperative NSA was significantly greater in the valgus-aligned group. Moreover, the NSA measured at the last follow-up was significantly greater the valgus-aligned group. In contrast, the NSA became considerably more varus-aligned in the anatomical group.
Conclusion
The appropriate valgus reduction and valgus bending plate fixation could lead to better short-term results and improve the ability of proximal humerus locking plates to prevent varus collapse and fixation failure.
Level of Evidence
Level III, retrospective cohort design.
Keywords: Proximal humerus fracture, Proximal humerus locking plate, Bent plate, Valgus alignment
Introduction
The surgical management of unstable proximal humerus fractures (PHFs) remains challenging because of their associated comminution, poor bone quality, and reduction loss [1–3]. With the development of locking plates, plate osteosynthesis has become the surgical treatment of choice for PHFs, especially for comminuted and osteoporotic fractures [4, 5]. Despite these improvements, the use of locked plating for the management of PHFs has been associated with a considerable number of complications and re-operation rates [4]. Although a locking plate acts as a tension band by holding the humeral head against varus forces, it often fails to prevent varus deformation [6]. Reduction loss, which was identified as one of the leading causes of re-operation in a systematic review by Thanasas et al. [7], occurs in 4.2–13.7% of PHF cases, most of which had varus deformities [8, 9]. Moreover, a study by Ravindra et al. reported that applying a fixed-angle locking plate flush to the bone might lead to medial displacement of the humeral head at the calcar, increasing the risk of losing fracture fixation [10]. Even though the PHFs were fixed using locking plates, 5.5°–10.1° of varus neck–shaft angle (NSA) changes were reported [5, 11].
We hypothesized that a slight valgus alignment, maintaining an NSA of around 140°, and valgus bent locking plate fixation against potential varus deformation would yield better results than the traditional fixed-angle technique. Therefore, the purpose of this study was to analyze the efficacy of valgus reduction and bent locking plate fixation by comparing short-term functional, clinical, and radiologic outcomes in patients with PHFs who were treated with either valgus bent locking plate fixation or conventional locking plate fixation.
Materials and Methods
An appropriate Institutional Review Board approved this study. We retrospectively reviewed 84 patients with PHFs who were treated using locking plate fixation by one surgeon between March 2014 and July 2019. Between March 2014 and October 2016, 33 consecutive patients with PHF underwent anatomical reduction and conventional locking plate fixation (the anatomical group); among them, 30 were evaluated, 2 were lost to follow-up, and 1 died of medical illness. Between November 2016 and July 2019, 30 consecutive PHF patients were treated with valgus reduction and valgus bent locking plate fixation (the valgus-aligned group); among them, 28 were evaluated, 1 was lost to follow-up, and 1 died of an unrelated cause. We categorized PHFs according to the Neer classification. Operative indications for PHFs included three-part and four-part fractures, two-part fractures with angulation > 45° and displacement > 1 cm, and two-part fractures with approximately 100% displacement or varus malalignment with medial cortical comminution that were deemed unstable by the surgeon.
Inclusion and Exclusion Criteria
The following were included in the study: (1) patients older than 18 years of age, (2) patients with displaced PHFs with a disrupted medial hinge, (3) patients with available functional and radiographic outcomes assessed at least 1-year prior to follow-up. The exclusion criteria were as follows: patients with (1) isolated greater tubercle fractures, (2) pathologic fractures, (3) open fractures, (4) multiple fractures, (5) fractures with humeral shaft extension, (6) fractures associated with neurovascular injury, (7) glenohumeral arthritis, (8) endosteal fibular strut allograft augmentation or additional medial buttress plate fixation, and (9) insufficient mental capacity to understand the trial or instructions for rehabilitation.
Surgical Technique
All operations were performed by a single surgeon. Fractures were exposed using the anterior deltopectoral approach under general anesthesia. Patients were placed in the beach-chair position at approximately 30° on a radiolucent table. Once the fractures were adequately exposed, horizontal mattress sutures (Ethibond #2–0; Ethicon®, Puerto Rico, Mexico) were used around the greater and the lesser tuberosities at the bone–tendon junctions to manipulate and reduce the tuberosity and humeral head fragments.
In the valgus-aligned group, an attempt was made to reduce the fracture with a slight valgus alignment of around 140°. The deformity was corrected using two 1.6 mm K-wires inserted into the humeral head, which were used as joysticks (Fig. 1C), or disimpacted with blunt elevators to maintain a slight valgus NSA of 140°. The valgus-reduced humeral head fragment was provisionally fixed to the shaft with 1.6 mm K-wires inserted away from the plate in an anteroposterior direction. The tuberosities were reduced after confirming the valgus alignment of the articular fragment through fluoroscopy. The reduced tuberosity fragments were secured to each other using a fiberwire suture. A 3.5-mm proximal humeral locking plate (PHILOS; Synthes, Paoli, PA, USA) was bent while ensuring that the cortical continuity of the medial column was not compromised (Fig. 1D). The plate was bent between the proximal and distal parts of the plate where the width of the plate shifted (Fig. 1E). The target angle was 140°, which was checked using a sterilized protractor. We aimed to insert the lower two locking head screws across the calcar and into the inferior quadrant of the humeral head to protect against varus re-displacement. When the plate was being secured with compression screws, care was taken so that the proximal part of the plate did not displace the medial column (Fig. 2).
Fig. 1.
a Postoperative radiograph and b computed tomography showing varus deformity in the proximal humerus fracture. c The deformity was corrected using two 1.6 mm K-wires inserted into the humeral head to be used as joysticks. d, f Proximal humeral locking plate was bent to the extent that the cortical continuity of the medial column was not compromised. e The bending was performed at the area (arrow) between the proximal and distal parts of the plate where the width of the plate was changing
Fig. 2.
a Intraoperative fluoroscopy showing varus deformity in proximal humerus fracture. b After the reduction using 1.6 mm K-wires, the medial cortical continuity was relatively intact. c The integrity of the medial column was compromised after screw insertion
In the anatomical group, the conventional fixation method was followed, wherein anatomical reduction of the PHFs was attempted and the locking plates were applied without bending. The surgery was completed after confirming fracture alignment and ensuring accurate plate and screw positioning through fluoroscopy. Bone substitutes (calcium phosphate) or fibular grafts were not used.
Postoperative Rehabilitation Protocol
All patients were treated with a similar postoperative rehabilitation protocol. A conventional sling was applied for 3 weeks after surgery. Patients started pendulum exercises 3 days after the relief of acute pain. Gentle, self-assisted passive range-of-motion exercises began after 3 weeks of immobilization. Depending on radiographic evidence of fracture-healing, active range-of-motion of the shoulder was allowed from 4 to 6 weeks. At 3 months after surgery, patients were allowed to perform activities of daily living. At 6 months postoperatively, they returned to their usual activities and restarted manual work.
Clinical and Radiographic Evaluation
For clinical evaluation, the American Shoulder and Elbow Surgeons (ASES) scores, the Disabilities of the Arm, Shoulder and Hand (DASH) scores, the Constant–Murley scores (CMS), and the passive range of movement were recorded at 1-year postoperatively and at the last follow-up.
For radiographic evaluation, standardized x-ray imaging was performed to evaluate the Neer classification, NSA, medial comminution, fracture-healing process, reduction loss, and implant-related problems. When a fracture could not be classified using standard radiographs or required a more thorough evaluation, three-dimensional computed tomography (CT) was performed. Standardized true anteroposterior radiographs and axillary lateral radiographs were examined immediately after surgery; at 6 weeks, 3 months, 6 months, and 1 year after surgery; and at the final follow-up. According to Agudelo et al., the NSA was defined as the angle between a line perpendicular to the line from the superior to the inferior border of the articular surface and a line bisecting the humeral shaft [9]. Changes in the NSA were measured by comparing the radiographs taken immediately after surgery with the ones taken at the last follow-up. When immediate postoperative radiographs were taken with the humerus internally rotated, we used intraoperative fluoroscopy images with the shoulder in neutral rotation instead of radiographs to determine the changes in the NSA. Humeral head height (HHH) was defined as the distance between the upper end of the plate and the upper end of the humeral head [12]. The difference in HHH between the immediate postoperative radiographs and the final radiographs was determined to calculate the change in HHH. Reduction loss was defined as a change of ≥ 10° in the NSA, a change of ≥ 5 mm in HHH, or fixation failure [13]. Based on both preoperative radiographs and CT scans, the medial metaphyseal comminution was classified as (i) none in cases without comminuted fractures and in cases with minimally displaced fragments or small fragments that do not affect stability, (ii) mild in cases with comminuted fragments that can be stabilized, and iii) severe in cases with bone defect or comminution that cannot be stabilized. All measurements were performed independently by two orthopedic surgeons who were unaware of the details of the study. In case of disagreement, the results were confirmed by another orthopedic surgeon. In this study, union of fracture site was defined as having no loss of the initial fracture reduction or no evidence of implant loosening, along with evidence of external callous formation.
Statistical Analysis
Data that are presented as summary statistics were calculated in terms of means and standard deviations. The differences in continuous variables between the groups were evaluated using the independent sample t-tests, whereas group differences in discrete variables were evaluated using the chi-square test or Fisher exact test. Unadjusted odds ratios and their respective 95% confidence intervals were calculated to assess the magnitude of the association. Statistical analyses were conducted using IBM SPSS version 23.0 (IBM Co., Armonk, NY, USA). Two-tailed P values < 0.05 were considered statistically significant.
Results
A total of 63 PHF patients who fulfilled the inclusion criteria were retrospectively enrolled in this study. Among them, five patients with incomplete follow-up data were excluded. Ultimately, 58 patients were enrolled in this study. These patients were divided into the valgus-aligned group (n = 28) and the anatomical group (n = 30) according to the reduction method and bending of the locking plate. The average follow-up period was 22.0 months (range 12–52 months).
Demographic Characteristics and Preoperative Radiologic Variables
Demographic data and preoperative variables of the valgus-aligned and anatomical groups are presented in Table 1. There were no significant differences in age (P = 0.244), sex (P = 0.601), mean follow-up period (P = 0.875), and the Neer classification (P = 0.276). The preoperative medial column comminution was similar between the two groups (P = 0.956). Moreover, the mean preoperative NSA were not significantly different between the two groups (123.8 ± 33.1° [95% confidence interval (CI), 110.17–137.51] vs. 131.9 ± 28.5° [95% CI: 121.20–142.51], P = 0.339) (Table 2).
Table 1.
Comparisons of patients’ demographic characteristics and preoperative variables between the valgus-aligned group and anatomical group
| Valgus aligned group (n = 28) | Anatomical group (n = 30) | P value | |
|---|---|---|---|
| Age (years) | 68.0 ± 13.1 | 63.5 ± 15.3 | .244 |
| Gender (male:female) | 7: 21 | 7: 23 | .601 |
| Mean F/U (months/range) | 21.9 (12–42) | 22.3 (13–52) | .875 |
| Mechanism of injury (SD:FD:TA) | 17:6:5 | 17:8:5 | .679 |
| Neer classification (2:3:4 part: Fx DL) | (7: 12: 8: 1) | (4: 19: 5: 2) | .276 |
SD slip down, FD fall down, TA traffic accident, Fx DL fracture dislocation
Table 2.
Comparisons of preoperative radiologic variables between the valgus-aligned group and anatomical group
| Valgus aligned group (n = 28) | Anatomical group (n = 30) | P value | |
|---|---|---|---|
| Medial column comminution | .956 | ||
| None (%) | 11 (39%) | 12 (40%) | |
| Mild (%) | 9 (32%) | 9 (30%) | |
| Severe (%) | 8 (29%) | 9 (30%) | |
|
Varus: neutral: valgus (varus ratio, %) |
18: 2: 8 (64.3%) | 15: 3: 12 (50.0%) | .177 |
| Mean of pre-operative NSA (°) |
123.8 ± 33.1 (95% CI: 110.17–137.51) |
131.9 ± 28.5 (95% CI: 121.20–142.51) |
.339 |
NSA neck–shaft angle, CI confidence interval
Radiological Outcomes
We compared the postoperative radiological results between the valgus-aligned group and anatomical group, and the results are presented in Table 3. According to the immediate postoperative radiographic evaluation, NSA was significantly greater in the valgus-aligned group than that in the anatomical group (141.9 ± 9.6° [95% CI: 137.93–145.85] vs. 131.3 ± 9.2° [95% CI 127.86–134.72], P < 0.001). Furthermore, the NSA recorded at the last follow-up was significantly greater in the valgus-aligned group than that in the anatomical group (138.1 ± 8.53° [95% CI: 134.55–141.59] vs. 122.4 ± 16.46° [95% CI: 116.20–128.50], P < 0.001). The change in the NSA was significantly more varus-aligned in the anatomical group than that in the valgus-aligned group (8.94 ± 12.71° [95% CI: 4.19–13.68] vs. 3.82 ± 8.03° [95% CI: 0.51–7.14], P = 0.046). However, there were no significant differences in postoperative HHH (1.87 ± 2.42 mm [95% CI: 0.87–2.87] vs. 2.72 ± 3.28 mm [95% CI: 1.36–3.77], P = 0.270).
Table 3.
Comparisons of postoperative radiological results between the valgus-aligned group and anatomical group
| Valgus aligned group (n = 28) | Anatomical group (n = 30) | P value | |
|---|---|---|---|
| Mean of post-operative NSA (°) |
141.9 ± 9.6 (95% CI: 137.93–145.85) |
131.3 ± 9.2 (95% CI: 127.86–134.72) |
< .001 |
| Mean of last NSA (°) |
138.1 ± 8.53 (95% CI: 134.55–141.59) |
122.4 ± 16.46 (95% CI: 116.20–128.50) |
< .001 |
| Mean NSA change (°) |
3.82 ± 8.03 (95% CI: 0.51–7.14) |
8.94 ± 12.71 (95% CI: 4.19–13.68) |
.046 |
| Mean humeral head height change (mm) |
1.87 ± 2.42 (95% CI: 0.87–2.87) |
2.72 ± 3.28 (95% CI: 1.36–3.77) |
.270 |
| Complication (Pt, %) | 3 (10.7%) | 7 (23.3%) | .312 |
| Varus collapse (Pt, %) | 1 (3.6%) | 4 (13.3%) | .362 |
NSA neck–shaft angle, Pt patients, CI confidence interval
Functional Outcomes
Table 4 shows a comparison of postoperative functional outcomes between the valgus-aligned group and anatomical group. Postoperatively, the ASES scores (76.12 ± 11.23 vs. 71.70 ± 10.87, P = 0.145), DASH scores (17.9 ± 10.26 vs. 22.8 ± 16.36, P = 0.201), and Constant–Murley scores (71.12 ± 10.40 vs. 71.33 ± 8.08, P = 0.934) did not show significant differences between the two groups. There were also no significant differences in other postoperative ranges of motion between the two groups.
Table 4.
Comparisons of postoperative functional outcomes between the valgus-aligned group and anatomical group
| Valgus aligned group (n = 28) | Anatomical group (n = 30) | P value | |
|---|---|---|---|
| Range of motion (°) | |||
| Mean flexion | 152.7 ± 16.49 | 148.6 ± 25.60 | .480 |
| Mean abduction | 156.0 ± 20.44 | 145.4 ± 23.93 | .082 |
| Mean int rotation | 76.6 ± 9.87 | 69.5 ± 16.83 | .069 |
| Mean ext rotation | 83.8 ± 7.68 | 80.17 ± 11.48 | .183 |
| ASES score | 76.12 ± 11.23 | 71.70 ± 10.87 | .145 |
| DASH score | 17.9 ± 10.26 | 22.8 ± 16.36 | .201 |
| Constant–Murley score | 71.12 ± 10.40 | 71.33 ± 8.08 | .934 |
ASES American Shoulder and Elbow Surgeons, DASH Disabilities of the Arm, Shoulder and Hand
Complications After Operation
Four patients in the valgus-aligned group and seven patients in the anatomical group had various postoperative complications (P = 0.312). One (3.6%) patient in the valgus-aligned group and four (13.3%) patients in the anatomical group showed varus collapse with screw penetration of the humeral head (P = 0.362). Two patients in the anatomical group required additional hemiarthroplasty after hardware removal due to nonunion of PHF and progression of varus deformity. It was possible to remove the hardware after bone fusion in two other patients. They were satisfied with the postoperative results and did not require additional surgery. One patient in the valgus-aligned group developed nonunion of the greater tuberosity and reduction loss (change in the NSA of 14.5°). The greater tuberosity displaced about 1 cm medially, and the final NSA was 157.9°. She did not complain of any discomfort; her final Constant–Murley score was 78. In the valgus-aligned group, one patient developed deep infection and needed hardware removal after fracture union. One patient in the valgus-aligned group and two patients in the anatomical group showed screw loosening and reduction loss. One patient in the anatomical group developed osteonecrosis and responded to conservative treatment. There were no other complications. However, the rate of complication (P = 0.312) and varus reduction loss (P = 0.362) were not significantly different between the two groups.
Discussion
This is the first study to describe the results of bent locking plate fixation to maintain alignment after intentional valgus reduction as a treatment of PHFs. We compared the results of valgus-aligned fractures with those of conventional anatomically reduced fractures that were previously treated by the same surgeon in our institution. In the valgus-aligned group, we aimed to reduce the fracture with a slight valgus alignment maintaining the NSA of around 140° followed by bent locking plate fixation to avoid displacing the humeral head medially. Overall, the valgus-aligned group did not show significant differences in clinical results. The valgus-aligned group showed a smaller change in the NSA, with an overall varus change of 3.82°, while the anatomical group showed an overall varus change of 8.94°. We found that the mean reduction in HHH and complication rates were lower in the valgus-aligned group than those in the anatomical group, although the differences were not statistically significant.
Despite the improvement in PHF fixation techniques with the advent of angular stable locking compression plates, the loss of medial support because of poor bone quality in the humeral head or medial comminution, leading to increased risk of malreduction and further varus subsidence, has not been overcome satisfactorily. In a recent retrospective study by Lee et al., a comparison between immediate postoperative NSA and the NSA recorded at around 14.2 months postoperatively revealed a varus change of 10.3° in 52 patients who were treated using the locking plates [5]. Kim et al. reported a change in the NSA in 80 patients with 3- or 4-part PHFs with medial comminution who were treated using the locking plates and inferomedial screws [11]. During an average follow-up period of 43 months, the change in the NSA was 5.5° in 52 cases with 3-part fractures and 7.9° in 28 cases of 4-part fractures. In most of these cases, varus changes occurred within the initial 12 weeks. The change in the NSA was significantly more varus-aligned in the anatomical group than that in the valgus-aligned group (8.94 ± 12.71° vs. 3.82 ± 8.03°) [11]. In our study, the anatomical group showed a significant decrease in the NSA postoperatively, which is consistent with the previous studies; however, we observed a significantly larger varus deformity in the anatomical group than that in the valgus-aligned group.
Most of the locking plates currently used in PHF treatment are designed to outline the lateral slope of a healthy humerus with the NSA of approximately 135°. An anatomical study by Ravindra et al. reported an average plate-bone distance of 2.5 mm with the 5-hole proximal humerus locking plates, or a more dramatic mismatch in PHFs with metaphyseal comminution [10]. According to them, when surgeons apply the locking plate flush to the proximal humeral shaft, even a small discrepancy in the metaphyseal region might lead to medial calcar displacement and varus malreduction, increasing the risk of losing fracture fixation. We bent the 5-hole locking plates to contour to the lateral slope of the humeri to maintain the cortical continuity of the medial column and reduction with valgus alignment. When the locking plates were bent in the valgus direction, the screws were oriented upwards; therefore, the calcar areas were more accessible for the screws in this study than those in the previous studies, as this study involved Asian patients who have smaller humerus lengths.
Previous studies have reported that varus malreduction of the humeral head may lead to poor outcomes [9, 14–18]. However, little knowledge exists regarding the results of valgus fixation of PHFs. A preliminary multicenter study by Agudelo et al., which included 147 PHF patients who were treated using locking plates, found a statistically significant association between varus malreduction immediately following surgery and early loss of fixation [9]. They reported a 30.4% incidence of loss of fixation in cases with varus malreduction, whereas in cases with postoperative NSA greater than 120°, the rate of loss of fixation was 11%. Other studies reported a significant association between insufficient arm elevation and clinical results in cases with the NSA in the antero-posterior plane less than 120° [14, 15]. A prospective study by Aggarwal et al. compared the Constant scores in patients with varus (< 120°), valgus (> 160°), and normal alignments. After 21.5 months of follow-up, a varus NSA observed at the last follow-up was found to be a strong predictor of poor Constant score (63.6). However, the final Constant score did not differ between patients with valgus alignment and those with normal alignment (73.4 vs. 73.05). In our study, neither functional scores nor postoperative range-of-motion had statistical significance, but the valgus-aligned group tended to have better results than the anatomical group. Although the difference was not statistically significant, there was less varus collapse with screw penetrations in the valgus-aligned group than in the anatomical group (3.6% vs. 13.3%).
Limitations of this Study
Our study had some limitations. First, it is not a randomized trial as the two groups underwent PHF reduction sequentially during two different periods. Second, the retrospective design of this study could introduce selection bias and potential confounding variables. Third, this study had relatively low statistical power due to the short-term follow-up and small sample size. Therefore, we could not confirm the clinical significance of valgus bent plate fixation of PHFs after slight valgus reduction.
Conclusions
This study has shown that valgus reduction and valgus bent locking plate fixation of PHFs provide good short-term results with respect to the maintenance of reduction. The appropriate valgus alignment of around 140° NSA has improved the ability of proximal humerus locking plates to prevent varus collapse and fixation failure.
Acknowledgements
We would like to thank Editage (www.editage.co.kr) for English language editing.
Funding
This work was supported by the 2018 Yeungnam University Research Grant. The authors, their immediate families, and any research foundations with which they are affiliated have not received any financial payments or other benefits from any commercial entity related to the subject of this article.
Data Availability
Any underlying research materials related to this paper can be accessed on request by the corresponding author.
Declarations
Conflict of interest
We have no conflict of interest in this paper. ICMJE forms for all authors are available online.
Ethical approval
Institutional review board approval has been obtained.
Ethical standard statement
This article does not contain any studies with human or animal subjects performed by the any of the authors.
Informed consent
As it was a retrospective study, IRB approved the exemption of the research consent form.
Footnotes
Publisher's Note
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Data Availability Statement
Any underlying research materials related to this paper can be accessed on request by the corresponding author.