Download The surgical approach, its vascular implications and the importance

14
The surgical approach, its vascular implications and the
importance of medial calcar support in maintaining fracture
reduction in locked plating of proximal humerus fractures
- A review.
Sreevathsa Boraiah, MD, Michael J Gardner, MD, Dean G Lorich, MD.
Orthopedic Trauma Service, Hospital for Special Surgery, 535 east 70 street,
New York, 10021.
Introduction
P
roximal humerus fractures are becoming increasingly
common with growing elderly population. These
fractures are often associated with osteoporotic bone
and dysvascularised fracture fragments, which may cause
difficulty in surgical fixation and poor outcomes. With the
emphasis on preservation of blood supply to the bone and
development of a less invasive means of obtaining fracture
reduction and fixation we sought a more direct means of
exposing the proximal humerus. The deltopectoral approach
provides anterior exposure of the proximal humerus yet the
fixation is applied laterally. When the greater tuberosity is
displaced posteriorly, access for manipulation and reduction
of the fragment requires wider exposure thereby increasing
soft tissue stripping. We sought a more direct lateral exposure
of the proximal humerus, which not only facilitates fracture
reduction via a laterally based plate but also preserves an
already compromised blood supply to the humeral head by
avoiding injury to the anterior circumflex humeral artery.
Further a more lateral approach facilitates fracture reduction
by working through the fracture line laterally and permitting
better access to anatomic, surgical neck and also to the
displaced greater tuberosity fragment.
Our first cadaver study analyses the lateral approach by
describing the axillary nerve anatomy in the region and safely
isolating it during plating. The next cadaver study assess the
vascular preservation of the humeral head by describing the
vascular anatomy and a watershed area devoid of a significant
blood supply that could be disrupted during the lateral
approach. The outcomes of our approach were analyzed in a
clinical series, which proves that the anterior deltoid
innervation was preserved after locked plating of proximal
Correspondence :
Sreevathsa Boraiah, MD
Orthopedic Trauma Service, Hospital for Special Surgery, 535 east 70 street,
New York, 10021.
humerus through the lateral approach.
Locked plating has offered a novel biomechanical
approach to stabilizing fractures. Few clinical reports exist on
results of locking plate fixation of proximal humerus
fractures; short-term functional outcomes and complication
rates have been variable. Locked plating is no panacea in the
absence of medial calcar support. Our study, which evaluates
radiographs in the immediate post operative period and
subsequent follow up studies reveal the importance of medial
calcar support in maintaining fracture reduction after locked
plating.
The surgical approach and its vascular
implications.
Lateral approaches to the proximal humerus have been
limited by position of the axillary nerve. Extensive dissection
through deltopectoral approach may further damage the
remaining tenuous blood supply to the proximal humerus. We
conducted two studies on the proximal humerus on the
cadavers. First study describes the surgical approach and the
axillary nerve and the next study describing the vascular
implications of minimally invasive plating using the lateral
approach to the proximal humerus.
Anterolateral Acromial Approach.
Poor results after plate fixation of plate of proximal
humerus using traditional deltopectoral approach requiring a
extensive soft tissue dissection may be related to fragment
devascularization during dissection or plating, or disruption
of critical blood supply to the humeral head. To develop a
more biologically focused and less invasive approach to the
Pb Journal of Orthopaedics Vol-X, No. 1, 2008
proximal humerus we explored an alternative surgical
approach to the proximal humerus. A direct approach to the
lateral proximal humerus historically has been restricted to 35 cm distal to the acromion because of the position of the
axillary nerve. We hypothesized that by using an anterolateral
acromial approach in cadaveric dissection the incision could
be distally extended by reliably palpating and protecting the
anterior axillary nerve motor branch. This depends on one
anterior motor branch crossing the anterior deltoid raphe and
the nerve being in a predictable location to allow safe
observation, as measured from consistent bony landmarks.
Twenty fresh frozen human cadaveric shoulders each
from a different donor were obtained from anatomic gift
registry. With shoulder in 00 abduction a skin incision was
made anterolateral acromion, extending approximately 8-10
cm distally. The subcutaneous tissue layer was then bluntly
dissected to identify the avascular raphe separating the
anterior and middle heads of deltoid (Fig 1, 3a). The superior
most part of the raphe was incised and the surgeon's finger
was inserted to sweep the undersurface of the deltoid. Once
the axillary nerve was palpated the incision in the raphe was
carefully extended down protecting the axillary nerve and the
posterior circumflex humeral artery (Fig 2, 3b).
Fig-1. Anterior and middle heads of deltoid after incising the
skin and the fascia.
Fig-2 Axillary nerve safely dissected out using the intermuscular
raphe between anterior and middle heads.
Surgical approach-proximal humeral fractures 15
Fig-3a,b. Schematic representation of the deltoid, the septum
and the axillary nerve dissected out through this septum.
Two separate observers made anatomical observations.
Axillary nerve was palpable as a cord like structure in the
loose areolar tissue between the deltoid and the raphe several
cm distal to the incision, and was distinct in all specimens to
both observers. The distance from the lateral prominence of
the greater tuberosity to the superior edge of the nerve was
35.5mm(range, 32.1-42.5 mm; 99% confidence interval,
34.0-37.omm), and the average distance from the
undersurface of the undersurface of the acromion to the
superior border of the nerve measured 63.3mm (range, 53.270.4 mm 99% confidence interval, 60.2-66.4mm). The nerve
could be elevated from the bone on an average of 13.4mm
before becoming taut. Reflection of the deltoid revealed that
no nerve branches other than the anterior axillary trunk
crossed the anterior deltoid raphe in any specimen. The last
branch of the nerve to the middle deltoid head raised an
average of 9.8mm before crossing the raphe.
The feasibility of the anterolateral acromial approach
was confirmed initially by the anatomic portion of this study.
The axillary nerve was readily palpated and subsequently
protected in all specimens by both observers. The axillary
nerve arises from the posterior cord of the brachial plexus and
passes through the quadrilateral space, dividing into anterior
and posterior branches. The anterior motor branch wraps
around the neck of the humerus and gives variable
innervations to the three heads of the deltoid. At the junction
of the anterior and middle head of the deltoid exists an
avascular raphe. The course of the axillary nerve distal to the
quadrilateral space has been described, but its precise position
as it crosses the anterior raphe has not been elucidated. The
anterior motor branch of the axillary nerve crosses the
humerus transversely at a variable distance as a single nerve
and penetrated the fascia before or after dividing into small
Boraiah et al.
16
branches. Most importantly, we found that no other branches
of the axillary nerve crossed at the level of the fibrous raphe
other than the results described above. This allowed the
deltoid to be split between the anterior and middle branch
after identification of the anterior branch without placing the
small branches at risk. Once the anterior branch was identified
a safe plane for splitting the deltoid to access the proximal
humerus was established.
Vascular implications of minimally invasive
plating of proximal humerus fractures
Poor outcomes of proximal humerus fractures treated
with traditional plating may due to devasucularisation of the
fracture fragments with subsequent delayed union, or
avascular necrosis (AVN) of the humeral head. This
devascularization may be due to trauma itself and/or surgical
dissection. Sturzenegger et al reported a more than 3 fold
increase of AVN after plating compared with minimally
invasive plating, and implicated additional iatrogenic
vascular insult with open reduction causing this result. AVN
rates have been reported between 4 and 10 % however the
follow up ranged only from 2 to 18 months. The standard
deltopectoral (DP) approach necessitates significant surgical
dissection and muscle retraction to gain adequate exposure to
lateral aspect of the humerus because it is an indirect approach
to the plating zone. Additionally, crucial blood supply to the
humeral head, the anterior circumflex humeral artery
(AHCA), courses laterally along the inferior border of
subscapularis tendon directly in the surgical field. This may
place it at risk during the DP approach, particularly with a
distorted anatomy as a result of fracture.
Six fresh-frozen cadaveric upper extremity specimens
were obtained from the anatomic gift registry. With the
shoulder in neutral rotation, an approximately 10 cm incision
was made beginning at the AL corner of the acromion and
carried distally. The fascia of the deep deltoid was split
superiorly to expose the raphe between the anterior and the
middle heads of the deltoid. After splitting the raphe 6cm
distally in the wound the axillary nerve was identified and
protected. A three hole 3.5-mm locking proximal humerus
plate (LCP< Syntese, Paoli, PA) was slid distally under the
axillary nerve, and positioned 8 mm distal to the rotator cuff
insertion centered on the greater tuberosity, as recommended
by the manufacturer. Screws were placed into the shaft and
head to stabilize the plate (Fig 4).
Fig-4. Locked plating performed after the safe isolation of the nerve.
After plating of the specimens, the axillary artery was found
in the axilla and cannnulated with a 14 gauge plastic catheter
and secured. The brachial artery was found distally in the
region of the mid humeral shaft and ligated. Black labeled
PMC 780 polymer (smooth-on, Inc., Easton, PA) was slowly
injected into the axillary artery using a ratcheting cement gun
to allow continuous ante grade perfusion of the latex and to
ensure adequate perfusion of the end arterioles of the
circumflex humeral system. Latex was allowed to polymerize
for 18 hours. Deltoid and the pectoral muscles were then
dissected and reflected to allow complete visualization of the
anterior and the posterior circumflex humeral arteries (Fig 5).
Pb Journal of Orthopaedics Vol-X, No. 1, 2008
Surgical approach-proximal humeral fractures 17
Clinical outcomes of locked plating of proximal
humerus.
Fig-5. Proximal Humerus with soft tissue stripping showing intact
vasculature after plating.
The ascending branch of the ACHA was visualized
proximally at the bicipital groove as the plates were being
applied. Further dissection after latex polymerization
revealed that adequate perfusion of the end branches of both
anterior and posterior circumflex vessels was achieved in all
cases. Tracing the course of the vessels revealed that no
vascular injury had occurred using this approach. A bare spot
was identified on the proximal lateral region of the humerus in
the region of the plate. This was a hypovascular area on the
greater tuberosity (Fig 6).
Fig-6. Bare spot on proximal Humerus.
A prospective cohort study was designed for all patients
undergoing open reduction and internal fixation of a proximal
humerus fracture using the anterolateral acromial approach.
Between May 2002 and July 2006 67 patients were treated
with this approach. 40 patients were followed up for at least
one year and formed the cohort of the study. The mean patient
age was 65.3 yrs (range, 21 to 84 yrs: median, 68 years). Five
patients were younger than 6o years. Fractures were classified
by senior surgeon, a fellowship trained orthopedic
traumatologist, according to the system of Neer. Seven
patients had 2- part fractures, 25 patients had 3- part fractures,
8 patients had 4-part fracture. Surgical indications were 2 part
fracture with 100% displacement or varus mal alignment and
comminution which were deemed to be unstable, as well as all
three part and four part fractures. Nine patients had humeral
locking nail and 31 patients had proximal humerus locking
plate using the technique described above.
Average clinical follow-up was 28 months (range 12-49
months), and 12 of the 40 patients had follow up greater than 2
years. Patient's outcomes were assessed using the Quick
DASH scale. This is a 11- item scale which has similar
discriminant ability, cross-sectional and retest reliability as
the full length DASH. Scores were calculated on a scale of 0100, similar to DASH, with higher scores indicating greater
disability. Quick DASH scores were also used to determine an
excellent (score< 20), good (20 –39), fair (40-60), or poor (>
60) clinical outcomes. In addition a focused physical
examination was performed to assess active range of motion,
for which humeral forward flexion and abduction were
measured with strict scapular stabilization. Manual testing of
forward flexion strength was measured on a scale of 0-5
compared to the contra lateral side, which was used as an
indicator of anterior deltoid and axillary nerve function.
In all cases, the anterolateral the approach was performed
and the axillary nerve was identified without difficulty. All
fractures healed, and no patients developed avasular necrosis
(AVN) of the humeral head. The average quick DASH score
for the entire group was 25.2 (range, 0 to 65.9; median, 22.7).
Thirty-three patients had good or excellent results, three
patients had poor results. Forward flexion range of motion
averaged 122 degrees (range, 20 to 180). One patient, an 84year-old male developed early painful stiffness and at final
evaluation had flexion of 30 degrees, abduction of 20 and a
quick DASH score of 62.5. In conclusion, the anterolateral
acromial approach allows minimally invasive access for the
treatment of proximal humerus fractures. The key aspect of
this approach, the identification and the protection of the
18
Boraiah et al.
axillary nerve, does not appear to have any deleterious effects
on the nerve function. On the contrary, nerve exploration may
reveal entrapment at the fracture site and allow mobilization,
as was the case in two patients in the series. The direct access
to the fracture site avoids exposure of the anterior critical
humeral head vascularity, and may decrease the rate of AVN.
The importance of medial calcar support in
maintaining fracture reduction.
Few clinical reports exist on the results of locking plate
fixation of the proximal humerus fractures, and short-term
functional outcomes and complications have been variable.
When locking plates are placed on the lateral proximal
humerus, the mechanical environment is such that fixed angle
screws are required to act as perpendicular struts to support
the humeral head fragment and resist varus displacement.
These forces may be exaggerated when there is lack of medial
column support, and the ability of these screws to perform this
function is unknown. Guidelines have not been provided
about the appropriate placement of locking screws such the
mechanical advantage is optimized.
We studied the radiographic behavior of proximal humerus
fractures treated with locking plates in a consecutive series of
patients with acute fractures. In addition we sought to
determine what patient factors, fracture patterns, reduction
variables, and implant placement affect the stability of
fracture fixation. We hypothesized that mechanical support of
the medial column would be particularly important for
establishing a stable construct.
Medical records and radiographs of 35 consecutive
patients treated at our institution from March 2003 to
February 2006 and who met the inclusion criteria were
analyzed. The “ humeral head height” relative to the plate was
measured for each radiograph, both initially and at the final
follow up, which allowed for subsequent loss of reduction.
Drawing 2 lines, both perpendiculars to the shaft of the plate,
did this measurement; one was placed at the top edge of the
plate and one was placed at the superior edge of the humeral
head and the distance between the 2 lines was measured and
designated as head height (Fig- 7).
Fig-7. Measurements for the humeral head height.
The change in this height from immediate postoperative
radiographs to the final follow up, at which time all fractures
were healed, was calculated. All radiographic measurements
were standardized for magnification with known implant size
and were performed by an independent observer. All cases
were subdivided into 2 groups according to the presence or
absence of medial mechanical support of the proximal
humeral head fragment. The fracture was considered
adequate considered support (+ MS group) if (1) the medial
pillar of the proximal humerus was not comminuted and
anatomically reduced (2) The shaft was medialised and
impacted into the head fragment; or (3) an oblique locking
screw was placed directly into the inferomedial quadrant of
the proximal humeral head fragment within 5mm of the
subchondral bone (Fig-8). Conversely, fractures that did not
fulfill one of these criteria were designated as having
inadequate medial support (- MS group) (Fig-9).
Pb Journal of Orthopaedics Vol-X, No. 1, 2008
Fig-8. Radiograph showing the inferomedial screws, which
augment medial calcar.
Fig-9. Radiograph demonstrating the loss of reduction of humeral
head .The image on the left demonstrates the inferomedial screw,
which was not placed (image on the right).
Average patient age was 62 years (range 23 to 89 years;
median, 62 years). Overall there were 6 two-part, 15 threepart, and 14 four- part fractures according to Neer
classification. Average follow up was 7 months (range, 6 to 77
weeks: median, 25 weeks). Eighteen patients were considered
to have medial support and were designated in the + MS
group. The average age of this group was 55 years. 9 patients
had an anatomic reduction of the medial cortex without
comminution, and 6 had 1 or 2 inferomedial screws placed;
three patients had both. In three patients Norian bone
substitute was placed. The average height loss of humeral
Surgical approach-proximal humeral fractures 19
head was 1.2mm(SD, 1.4mm), and the maximum was 4.1mm.
One 61-year-old patient with a 3 part comminuted surgical
neck and greater tuberosity fracture, had an inferomedial
screw placed but had screw penetration through the humeral
head and required revision surgery for screw removal at 3
months postoperatively. All patients healed without any
delayed union. There were 17 patients remaining in the –MS
group. The breakdown of fracture types in this group were 2
two-part, 7 three-part, and 8 four-part, which was not
significantly different between the groups. Twelve patients
had malreduction with lateral displacement of the shaft
fragment, without opposition of the medial cortex, and 5 had
significant comminution; no patient had a screw placed in the
inferomedial region. Humeral head height loss in this group
averaged 5.8mm (SD, 3.9mm), which was significantly
greater than in the +MS group. The maximal humeral height
loss was 13.6mm, and 9 patients had greater than 5mm of
height loss (p <0.001). Of the 17 patients without medial
support, 5 had screw penetration of the articular surface and, 2
of who had loosening of other screws and 2 of who underwent
revision surgery for screw removal. Despite the fracture
migration and implant cutout in this group, all fractures
achieved solid bony union in timely fashion.
The mechanical performance of proximal humeral
locking plate has been variable according to previous authors.
A preliminary report of a multi center study of 147 patients
found a 14% incidence of mechanical complications, and this
was closely related to mechanical varus malreduction. The
locking plate may be adjusted slightly proximally or distally,
and is often placed where it best fits the anatomy of lateral
cortex and greater tuberosity, without particular attention to
the location of screws in the proximal fragment. But
ultimately, according to our results, if the position of the plate
is not chosen by ensuring that the inferomedial screws will be
placed in the proper location, screws can be easily misplaced
and early mechanical failure may become more likely. It
seems that constructs that have screws only superiorly in the
humeral head without fixation-anchored inferomedially,
especially when medial communition or malreduction is
present, may be ineffective in maintaining fracture reduction.
In cases where stable bony medial column support
cannot be achieved secondary to fracture comminution we
have sought to support our fixed construct with additional
endosteal support. This stable additional endosteal support
was achieved by placing either an intramedullary plate which
was locked in by the screws running from the extramedullary
laterally based locking plate (Fig-10), or more recently by
placing an allograft fibula endosteally and locking it with
laterally placed locking plate (Fig-11). A clinical series of this
pattern of medial calcar augmentation is the latest study in the
spectrum of treatment of proximal humerus fractures. The
result of this study shows that the fracture reduction can be
maintained within 1mm margin.
Boraiah et al.
20
margin of 1mm. With the treatment of proximal humerus
fractures still evolving, good reduction of medial cortex and
augmentation of medial calcar may be a solution for better
outcomes.
Fig-10. Radiograph showing the augmentation of medial calcar
with an endosteal plate locked by the screws running from the
laterally based locking plate.
Fig-11. Radiograph showing the augmentation of medial calcar
with an allograft fibula placed in the intramedullary cavity locked
with screws from locking plate.
In conclusion, minimally invasive plating using a direct
lateral approach is a safe and effective way of plating the
proximal humerus fractures with very little vascular insult.
We had no reported incidence of axillary nerve palsy,
particularly the branch that supplied the anterior head of
deltoid. Also after understanding the importance of medial
calcar support, our prospective study evaluating the outcomes
of augmentation of medial calcar shows that the fracture
reduction of the humeral head can be maintained within a
References
1. Gardner MJ, Griffith MH, Dines JS, Briggs SM, Weiland AJ, Lorich DG.
The extended anterolateral acromial approach allows minimally
invasive access to the proximal humerus. Clinical orthopaedics and
related research 2005:123-9.
2. Gardner MJ, Voos JE, Wanich T, Helfet DL, Lorich DG. Vascular
implications of minimally invasive plating of proximal humerus
fractures. Journal of orthopaedic trauma 2006;20:602-7.
3. Gardner MJ, Weil Y, Barker JU, Kelly BT, Helfet DL, Lorich DG. The
importance of medial support in locked plating of proximal humerus
fractures. Journal of orthopaedic trauma 2007;21:185-91.
4. Kristiansen B, Christensen SW. Plate fixation of proximal humeral
fractures. Acta Orthop Scand 1986;57:320-3.
5. Sturzenegger M, Fornaro E, Jakob RP. Results of surgical treatment of
multifragmented fractures of the humeral head. Archives of orthopaedic
and trauma surgery 1982;100:249-59.
6. Traxler H, Surd R, Laminger KA, Windisch A, Sora MC, Firbas W. The
treatment of subcapital humerus fracture with dynamic helix wire and
the risk of concommitant lesion of the axillary nerve. Clinical anatomy
(New York, NY 2001;14:418-23.
7. Kontakis GM, Steriopoulos K, Damilakis J, Michalodimitrakis E. The
position of the axillary nerve in the deltoid muscle. A cadaveric study.
Acta Orthop Scand 1999;70:9-11.
8. Duparc F, Bocquet G, Simonet J, Freger P. Anatomical basis of the
variable aspects of injuries of the axillary nerve (excluding the terminal
branches in the deltoid muscle). Surg Radiol Anat 1997;19:127-32.
9. Wijgman AJ, Roolker W, Patt TW, Raaymakers EL, Marti RK. Open
reduction and internal fixation of three and four-part fractures of the
proximal part of the humerus. The Journal of bone and joint surgery
2002;84-A:1919-25.
10. Szyszkowitz R, Seggl W, Schleifer P, Cundy PJ. Proximal humeral
fractures. Management techniques and expected results. Clinical
orthopaedics and related research 1993:13-25.
11. Speck M, Lang FJ, Regazzoni P. [Proximal humeral multiple fragment
fractures--failures after T-plate osteosynthesis]. Swiss surgery =
Schweizer Chirurgie = Chirurgie suisse = Chirurgia svizzera 1996:51-6.
12. Bathis H, Tingart M, Bouillon B, Tiling T. [Surgical treatment of
proximal humeral fractures. Is the T-plate still adequate osteosynthesis
procedure?]. Zentralblatt fur Chirurgie 2001;126:211-6.
13. Hessler C, Schmucker U, Matthes G, Ekkernkamp A, Gutschow R,
Eggers C. [Results after treatment of instable fractures of the proximal
humerus using a fixed-angle plate]. Der Unfallchirurg 2006;109:86770, 72-4.
14. Koukakis A, Apostolou CD, Taneja T, Korres DS, Amini A. Fixation of
proximal humerus fractures using the PHILOS plate: early experience.
Clinical orthopaedics and related research 2006;442:115-20.
15. Plecko M, Kraus A. Internal fixation of proximal humerus fractures
using the locking proximal humerus plate. Operative Orthopadie und
Traumatologie 2005;17:25-50.
16. Fankhauser F, Boldin C, Schippinger G, Haunschmid C, Szyszkowitz R.
A new locking plate for unstable fractures of the proximal humerus.
Clinical orthopaedics and related research 2005:176-81.