Modified medial minimally invasive plate
osteosynthesis techniques for the treatment of
distal third diaphyseal fracture of humerus using a
double plate technique
Youyou Ye
Fuzhou Second Hospital
Yanbin Lin ( 746001548@qq.com )
Fuzhou Second Hospital
Chunling Wu
Fuzhou Second Hospital
Yunzhe Zhu
Fuzhou Second Hospital
Research Article
Keywords: Distal third diaphyseal fracture of humerus, Modified medial approach, Minimally invasive
plate osteosynthesis, Ulnar nerve ·, Radial nerve
Posted Date: May 19th, 2023
DOI: https://doi.org/10.21203/rs.3.rs-2908126/v1
License: This work is licensed under a Creative Commons Attribution 4.0 International License.
Read Full License
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Abstract
Purpose
The surgical approach and the placement of plates for the treatment of distal third diaphyseal fracture of
the humerus are controversial. The aim of this retrospective study was to evaluate the clinical and
radiographic outcomes when modified medial minimally invasive plate osteosynthesis (MIPO)
techniques for the treatment of distal third diaphyseal fracture of the humerus using a double plate
technique were performed.
Methods
A total of 20 patients with a distal third diaphyseal fracture of the humerus were selectd from our
hospital. Patients were seen between January 2017 and May 2019. They were treated with a modified
medial approach combined with MIPO techniques using a double plate technique. Patient demographics,
operation time, bleeding volume, union time, complication, the mean fracture length(FL) and distal
cortical length (DCL), and the number of screws in the distal fragment were analyzed. The function of the
shoulder and elbow were evaluated using Neer's assessment of the shoulder and Mayo's assessment of
the elbow.
Results
The FL was 57.7 ± 7.7mm and the DCL 39.1 ± 5.2mm. The mean operative time was 88.3 ± 12.6min
(range 60-110min). The mean blood loss on surgical treatment was 47.8 ± 10.6ml(range 30-60ml). Bone
healing was observed in all patients from 10 to 14 weeks (average 11.9 ± 1.8) and there were no
complications recorded. All the patients had good function of both the shoulder and elbow. The
maximum flexibility of the elbow ranged from 130° to 145° (average 138.5 ± 4.9°) with maximum
flexibility straightness 0° to 5° (average 2.2 ± 1.5°). The Mayo elbow joint function score was 80–100
(average 92.7 ± 5.1). The Neer shoulder joint function score was from 85–100 (average 93.6 ± 3.5).
Conclusion
The modified medial approach had the advantages of no iatrogenic radial nerve nor ulnar nerve injuries.
The anterior and the medial side plate were fixed perpendicular to the distal humerus and can offer higher
stability at the same time producing better shoulder and elbow joint function.
Introductions
A distal third diaphyseal fracture of humerus is often caused by indirect violence with oblique and spiral
fracture shape. Due to high rates of nonunion and radial nerve injury, the treatment of this kind of fracture
is very tricky [1]. Surgical treatment can be selected from external fixation or an intramedullary nail and
plate. It is generally considered that open reduction and internal fixation with a plate is the most reliable
treatment method [2]. Single plate fixation is the choice of most surgeons [3, 4]. However, it was reported
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that the single plate fixation humeral shaft nonunion and internal fixation failure rate can reach 15% [5].
Therefore, to reduce the complications of such fractures, the stability of the distal fracture needs to be
fixed by at least three or four screws, for which it is obvious that only a double plate can facilitate. Some
physicians believe that this kind of fracture should be treated with double plates [6, 7]. The approaches
for treating distal third diaphyseal fractures of the humerus have been reported using anterior [8],
anterolateral [9], and posterior [10] approaches, each of which has both advantages and disadvantages.
An anteromedial MIPO approach that can be performed through the internervous plane beneath the
brachialis muscle without exposing any nerves or causing any muscle splitting with a 12-hole plate was
reported which provides less invasive surgical dissection, allows the use of longer distal screws, and
achieves better cosmesis [11]. However, this approach is limited in its ability to expose the anterior of the
distal humerus, especially when it required plate fixation. Therefore, a modified medial approach was
proposed to provide a greater range of exposure in our study. The purpose of this study was to describe
this modified medial approach combined with the Mipo techniques for the treatment of a distal third
diaphyseal fracture of the humerus using a double-plate technique and to assess its clinical outcome.
Materials and Methods
The Human Experimentation and Ethics Committee of our hospital's institutional review board gave its
approval to the study design and data collection (2023071). The twenty patients were seen between
January 2017 and May 2019. Patients presented with a distal third diaphyseal fracture of the humerus
that underwent open reduction and internal fixation with a double-plate using the modified medial
approach combined with Mipo techniques (Table 1). The mean follow-up period was 21.8±2.9 months
(range, 18–26 months). Open fractures, pathological fractures, intercondylar fractures of the humerus
and fractures combined with radial nerve injuries were excluded. There were 14 males and six females.
The average age was 34.6±8.9 years (range, 19-55 years). There were six cases on the left and 14 cases
on the right. Causes of injury: motor vehicle accident injury in six cases, arm wrist injury in six cases, and
fall injury in eight cases. According to AO/ASIF fracture classification there were three A1 cases(15%),
one A2 case (5%), nine B2 cases (45%), and seven B3 cases (35%). All patients were operated on within 2-
7 days (mean, 4.8±1.1 days) of injury. All the patients had completed X-ray and 3D CT examination
before their operation. A 4.5mm Narrow locking compression plate (LCP; Synthes®, Swiss) and a 3.5mm
LCP reconstruction plates (Synthes®, Swiss) were used for fixation. The length of the plate was
determined by the fracture line, ensuring that both plates were fixed with at least two screws at the distal
fragments. The mean fracture length and distal cortical length were analyzed pre-operation. The length of
the fracture was defined as the longest fracture line observed in the X-ray image and the distal cortical
length defined as the distance between the upper edge of the olecranon and the distal end of the fracture
line ( Fig. 1).
Surgical technique
The patient was placed in a supine position after general anesthesia with the upper arm placed at 90
degrees of abduction on a radiolucent table and the forearm in full supination (Fig. 2). For distal access,
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a longitudinal 5cm incision was made at a position about 1.5cm above the normal ulnar approach [11].
The basilic vein was first identified and protected (Fig. 3). A gap between the biceps brachii and the
medial part of the brachialis may be visible with careful blunted dissection of the bottom edge of the
basilic vein (Fig. 3). The medial third side of the brachialis was incised in a longitudinal manner and the
fracture ends exposed, cleaned, reduced, and temporarily fixed with a Kirschner wire (Fig. 3). The ulnar
nerve was indirectly protected by retracting the triceps brachii muscle posteriorly, while the brachialis
muscle was pulled forward to protect other neurovascular structures. About 4/5 of the distal anterior and
the entire medial part of the distal humerus could be exposed using the modified medial approach (Fig.
3). Internal fixation of the distal medial of the humerus can be performed with a 3.5mm LCP
reconstruction plate and two to three screws were used for proximal and distal fixation. Subsequently, the
pectoralis major deltoid approach, which has an incision about 4cm long between the proximal biceps
brachialis muscle laterally and the deltoid muscle medially, was applied for the proximal incision. In the
distal incision, a sub-brachialis extraperiosteal tunnel was created by inserting a 4.5mm Narrow locking
compression plate (LCP; Synthes®, Swiss), with a threaded drill sleeve attached as a handle, into the
most distal hole for tunneling and plate insertion into the sub-brachialis from the distal to the proximal
incision. On the distal fracture part, two to three locking screws were inserted, and on the proximal
fracture region, two to three screws (Fig. 4). Good fracture reduction, adequate plate placement, and the
right length screws were all confirmed by intraoperative X-ray fluoroscopy. After extensive irrigation the
wound was closed in layers and a rubber drainage was inserted. No external immobilization was used.
Rehabilitation typically starts two days following surgery with passive forward flexion, with a goal of 0-
100° by the end of the second week to allow for wound healing. Exercises for the pendulum function,
raising, and shoulder joint abduction should all be done at the same rehabilitation session. The elbow
joint's flexion and extension function were exercised with a partial load after six weeks. By three months,
or when an X-ray image analysis revealed that the bones had healed, shoulder and elbow joint movement
under heavy weightlifting was possible.
Postoperative evaluation and management
We recorded the operation time, volume of bleeding, union time, and complications (whether there was
radial nerve, ulnar nerve, or musculocutaneous nerve injury). Standard anteroposterior and lateral views
of the humerus were taken immediately following surgery and during the follow-up assessments at four,
eight, and 12 weeks postoperatively, and at six- and 12-months following surgery. The number of screws
used, and the fixed distal cortical point fragments were counted. The function of the shoulder was
evaluated by Neer’s criteria, which consisted of pain (none to totally disabled), function (strength, reach,
and stability), range of motion (rom) (flexion, abduction, extension, external rotation, and internal
rotation), and anatomy (rotation, angulation, joint congruity, retracted tuberosities, metal failure, myositis,
nonunion, and AVN). The function of the elbow was evaluated by Mayo’s criteria, which is based on
assessment of pain (maximum score 45 points), ulnohumeral motion (20 points), stability (10 points),
and ability to perform five functional tasks (25 points).
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Results
The mean fracture length was 57.7±7.7mm and distal cortical length 39.1±5.2mm. The mean operative
time was 88.3±12.6min (60-110min). The mean blood loss on surgical treatment was 47.8±10.6ml (30-
60ml). All incisions healed without complications. Bone healing was observed by radiology in all patients
by 10 to 14 weeks (average, 11.9±1.8 weeks), and there were no implant failures nor where there any
iatrogenic radial, ulnar, or musculocutaneous nerve injuries. The 7-hole 3.5 LCP reconstruction plate was
the most commonly used, 10 cases in total, whereas the 4.5mm narrow LCP, including the 10-hole to 14-
hole plates, were used in other cases. In every case the distal fragments were secured by a minimum of
four screws and a maximum of 10 cortical points (average, 8.7±1.2). The mean number of screws used in
the 4.5mm LCP and 3.5mm recon plate were 2.1±0.3 and 2.4±0.5 (Table 2). At the final follow up all
patients had good function of their shoulder and elbow. The maximum flexibility of the elbow was from
130° to 145° (average, 138.5±4.9°), with a maximum flexibility straightness of 0° to 5° (average,
2.2±1.5°). The Mayo elbow joint function score was 80-100 (average, 92.7±5.1). The Neer shoulder joint
function score was 85-100 (average, 93.6±3.5) (Table 3).
Discussion
The surgical treatment of the distal third diaphyseal fracture of the humerus includes external fixation,
intramedullary nail and plate, and internal fixation. Plate fixation has long been considered the most
reliable treatment for such fractures [12]. However, it has been reported in the literature that the incidence
of nonunion of these fractures is still as high as 5%-15% [13]. Oliver et al. [14] believe that 75% of the
failure of the treatment of humerus fractures in the distal third diaphyses was due to the instability of the
initial fixation. We reviewed cases and found that the farther down the fracture line, the more limited were
the internal fixation options. The average fracture length in the patients in this study was 57.7±7.7mm,
and the average distal cortical length was 39.1±5.2mm. For such fractures, either intramedullary fixation
or single-plate fixation could not provide an effective working distance and internal fixation stability.
Therefore, we suggest that this part of the fractures should be specifically referred to as a distal third
diaphyseal fracture of the humerus. Although conventional single-plate fixation has the advantage of less
interference with soft tissue, blood vessels, and nerves [15,16], it is often unstable to fix the distal third
diaphyseal fracture of the humerus with this fixation. Immobilization is often required in the early
postoperative period, thus losing the opportunity of early functional exercise. Many studies [17,18] have
shown through biomechanical analysis that a single plate is suitable for fracture types of the middle and
upper part of the humerus, while a double plate and double column fixation can provide better anti-
bending and anti-torsion forces for fractures of the distal humerus. Since the fracture characteristics of
the distal third diaphyseal fracture of the humerus determine if the distal end of the fracture is fixed with
a single plate, it is difficult to achieve with three screws and six cortical fixations, and therefore, the
fixation can be unstable. However, double plate fixation can ensure at least four screws and eight cortical
fixations at the distal end of the fracture, thus providing strong resistance to torsional stress.
Kosmopoulos et al. [19] used biomechanical experiments to confirm this view. Early functional exercises
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of the elbow and shoulder are the key factors to achieving good postoperative function. Relevant studies
have used a double plate in clinical practice and also achieved satisfactory results [20,21]. The twenty
patients in this article were treated with the modified medial approach combined with Mipo techniques
using a double-plate technique. At least four screws were fixed at the distal end of the fracture, and the
average (8-12) cortical fixation was achieved. Through strong fixation the patient was able to start
functional exercise of the shoulder and elbow joint on the second day after surgery. Due to the
anatomical reduction and biomechanical stability the fracture healing was fast with a fracture healing
time of 11.9±1.8 weeks. Due to the early functional exercises, satisfactory elbow flexion and extension
function were obtained (Fig. 4).
Currently, surgical approaches for distal third diaphyseal fractures of the humerus mainly include
anterolateral, posterior, medial, direct anterior, and anterior MIPO approaches. Among them, the
anterolateral approach is the most used in clinical practice. However, this approach requires a large
incision and routine exposure of the radial nerve, which often results in iatrogenic radial nerve injury [22].
Rafael-Kakazu et al. [23] reported that the probabilities of iatrogenic radial nerve injury caused by the
anterolateral approach, anterior approach, and posterior approach were 1/5, 1/25, and 1/9, respectively.
The anterior MIPO technique approach has the advantage of avoiding the risk of iatrogenic radial nerve
injury by not requiring exposure of the radial nerve. Additionally, it maintains the biological integrity of the
fracture end, resulting in a smaller incision, less trauma, minimal damage to the blood supply, minimal
intraoperative bleeding, high fracture healing rate, and good recovery of the shoulder joint function [24].
However, it cannot be used for anatomic fracture end reduction. In recent years, the ulnar approach to the
distal humerus has gained acceptance and been increasingly applied in clinical practice [25]. However,
due to the complexity of blood vessels and nerves in the medial incision, a high level of anatomical
knowledge is required to avoid iatrogenic injury, which makes this approach rarely used. Nevertheless,
other researchers argue that the medial incision is not only concealed but also safe and minimally
invasive [26]. Buranaphatthana reported the fixation of twenty cadaveric arms utilizing the anteromedial
approach and 12-hole precontoured narrow locking compression plates (LCP) using the MIPO technique
[11]. Between the biceps and deltoid muscles a proximal approach was used to reach the bone. The
brachialis was raised from the medial intermuscular septum during the distal approach. From distal to
proximal, the plate was placed into the brachialis tube on the anteromedial face. In our study we
improved the medial approach through clinical studies. A longitudinal 5cm incision was made at a
position about 1.5cm above the normal ulnar approach [11]. With the modified medial approach,
approximately 4/5 of the distal anterior area and the entire medial part of the distal humerus was
accessible. Internal fixation of the distal medial and anterior of the humerus can be performed with a
3.5mm LCP reconstruction plate and a 4.5mm Narrow locking compression plate. Therefore, the distal
humerus did not need to supplement the skin incision, as long as the front side plate was placed slightly
on the ulnar side the distal screw could be directly inserted through the modified medial incision. While
reducing the surgical incision it also avoided the risk of musculocutaneous nerve injury. As a result of
strong fixation, we could obtain better shoulder and elbow joint function.
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The conventional anterior MIPO technique necessitates the division of the brachialis muscle, which may
harm the radial nerve or muscular branches and denervate some muscle, resulting in motor weakness.
The brachialis muscle was also separated in our investigation, but the aforementioned problems did not
occur. We consider the following reasons our procedure avoided these complications:(1) The
conventional anterior MIPO approach requires division of the brachialis muscle at both the distal and
proximal ends, with the distal incision at the lateral radialis. The brachialis muscle in these regions is
where the branches of the radial nerve and musculocutaneous nerve pass through, so it is easily injured
and leads to muscle paralysis [27]. However, we split only the inner 1/3 of the brachialis muscle, which is
a relatively safe area. (2) Brachialis muscle scarring and inadequate postoperative rehabilitation may be
involved in limiting the elbow range of motion with the conventional anterior MIPO approach. Our
modified medial MIPO technique with a dual plate technique was able to allow early functional exercise
and avoids these complications.
Conclusion
Based on the above our study shows that the modified medial approach combined with the anterior Mipo
approach has the advantages of being minimally invasive, having strong fixation, and avoiding iatrogenic
radial nerve and ulnar nerve injury in the treatment of distal third diaphyseal fracture of the humerus. For
such fractures, it is an optional treatment and worthy of clinical application.
Declarations
Conflict of interest :The authors declare no competing interests.
Funding :The authors received financial support from Fujian Provincial Clinical Medical Research Center
for First Aid and Rehabilitation in Orthopaedic Trauma (2020Y2014) and Fuzhou Health Technology
Project(2021-S-161).
Data transparency:All data generated or analysed during this study are included in this published
article and support our published claims and comply with field standards [and its supplementary
information files].
Code availability: Not applicable.
Consent to publish:The authors affirm that human research participants provided informed consent for
publication of the images in Figure(1-4).
Consent to participate:Informed consent was obtained from all individual participants included in the
study.
Author contribution:All authors contributed to the study conception and design. Material preparation, data
collection and analysis were performed by Chunling Wu, Yunzhe Zhu. The first draft of the manuscript
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was written by Youyou Ye and all authors commented on previous versions of the manuscript.Yanbin Lin:
design of the study, surgery and general supervision of the research group.All authors read and approved
the final manuscript.
Ethics approval :All procedures in studies involving human participants were performed in accordance
with the ethical standards of the institutional and/or national research committee and with the 1964
Helsinki Declaration and its later amendments or comparable ethical standards. This was a retrospective
study, and IRB approval was obtained (approval No. 2023071).
Acknowledgments:This paper is supported by Fujian Provincial Clinical Medical Research Center for First
Aid and Rehabilitation in Orthopaedic Trauma (2020Y2014) and Fuzhou Health Technology Project(2021-
S-161).
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Tables
Table 1 Distal third diaphyseal fracture of humerus according to age, classification of fractures and
fracture length outcomes
Characteristics Values (N=20 patients)
Mean age (years ± SD) 34.6 ± 8.9
Male, n (%) 14(70)
Right humerus injury, n (%) 14(70)
Mean distal cortical length, n (mm) 39.1±5.2
Mean fracture length,n(mm) 57.7±7.7
Mean interval between injury to operation(days ± SD) 4.8 ± 1.1
Mean follow-up, n (months± SD) 21.8±2.9
Injury mechanism, n (%)
motor vehicle accident injury 6(30)
arm wrist injury 6(30)
Falls from standing height 8(40)
AO Classification, n (%)
A1 3(15%)
A2 1(5%)
B2 9(45%)
B3 7(35%)
Table 2 Plate length and mean number of screws, mean cortical points of screws fixed on distal
fragment
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Parameters Values
4.5-mm narrow LCP length (%)
10 hole 6(30)
12 hole 9(45)
14 hole 5(25)
3.5-mm reconstruction LCP length (%)
6 hole 5(25)
7 hole 10(50)
8 hole 5(25)
Mean number of screws fixed on distal fragments
On 4.5-mm narrow LCP 2.1 ± 0.3
On 3.5-mm reconstruction LCP 2.4 ± 0.5
Mean cortical points of screws fixed on distal fragment 8.7±1.2
Table 3 Clinical and Functional outcomes of patients with distal third diaphyseal fracture of humerus
Parameters Values
Mean operative time ±SD(min) 88.3±12.6
Mean blood loss ±SD (ml) 47.8±10.6
Mean time to union ±SD (weeks) 11.9±1.8
Complication (%) 0(0)
Elbow range of motion±SD (°)
Elbow extension 2.2±1.5
Elbow flexion 138.5±4.9
Mayo elbow joint function score±SD 92.7±5.1
Neer shoulder joint function score±SD 93.6±3.5
Figures
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Figure 1
Positive and lateral X-ray of a typical distal third diaphyseal fracture of humerus: The mean fracture
length (FL) is defined as the longest fracture line observed in the X-ray image; The distal cortical
length(DCL) is defined as the distance between the upper edge of the olecranon and the distal end of the
fracture line.
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Figure 2
Operative incision and schematic diagram of the cross-sectional anatomy（a：Epicondyle of the humerus）
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Figure 3
Exposure and fixation were performed by the modified medial approach: a The basilic vein were defined
and exposed as major markers（The blue dotted line is the basilic vein）；b A gap between the biceps
brachii and the medial part of the brachialis may be visible with careful blunted dissection of the bottom
edge of the basilic vein; c The medial third side of the brachialis was incised in a longitudinal manner; d
The fracture ends can be exposed, cleaned, reduction and temporarily fixed with kirschner wire; e About
4/5 of the distal anterior area and the entire medial part of the distal humerus could be exposed(The red
rectangular area in the figure is the exposure range); f Anterior and the medial side plate were fixated
perpendicular to the distal humerus.
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Figure 4
Clinical and radiological outcomes of a patient with distal third diaphyseal fracture of humerus： a The
final follow-up X-ray; b,c The range of motion at final follow up of a 34 year-old male were shown.
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