Techniques in Shoulder & Elbow Surgery 8(4):204–212, 2007
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Ó 2007 Lippincott Williams & Wilkins, Philadelphia
T E C H N I Q U E
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Unicompartmental Elbow Replacement:
Development of a Lateral Replacement Elbow
(LRE) Arthroplasty
Joseph Pooley, MD, FRCS, MBBS
Upper Limb Department
Queen Elizabeth Hospital and North East Surgical Centre
Gateshead, UK
| ABSTRACT
Postmortem studies have shown that advanced degenerative changes occur in the radiocapitellar (lateral) compartment of elbow joints in elderly subjects in whom
the humeroulnar (medial) compartment remains well preserved. We have observed a similar pattern of degenerative change in younger symptomatic patients undergoing
arthroscopic debridement procedures or open arthrolysis.
We have found that the clinical improvement obtained
by these procedures is unpredictable, and persisting rest
pain is a problem. We therefore recognized the need to
develop prosthetic components with which to replace
or resurface the articular surfaces of the lateral compartment of the elbow.
The resulting lateral resurfacing elbow arthroplasty
began clinical evaluation in September 2005 and to
date has been inserted into 44 elbows (43 patients).
The purpose of this article is to outline the design rationale, describe the surgical technique, and present the
early results of the lateral resurfacing elbow arthroplasty.
Our early experiences have broadened our indications
for surgery beyond patients with primary osteoarthritis
and now include patients with secondary osteoarthritis
due to trauma or rheumatoid disease.
Keywords: elbow arthritis, elbow arthroplasty, unicompartmental arthroplasty, surface replacement, surgical
approach to elbow
oodfellow and Bullough,1 almost 40 years ago,
first described the pattern of articular cartilage
wear resulting from degenerative change in the elbow
joint. More recent postmortem studies have similarly
shown that advanced degenerative changes can develop
in the radiocapitellar (lateral) compartment of elbow joints
of elderly subjects in which the humeroulnar (medial)
G
Reprints: Joseph Pooley, MD, FRCS, MBBS, 12 Darras Rd, Ponteland,
Newcastle Upon Tyne, NE20 9PA, United Kingdom (e-mail:
[email protected]).
204
compartment remains remarkably well preserved.2Y4 The
pattern of articular cartilage wear in the cadaver elbow is
therefore well documented, but the clinical significance of
these postmortem findings in elderly subjects, whose
medical history was not recorded, remained unknown.
We became aware of this pattern of degenerative
change developing in younger symptomatic patients
largely as a result of our increasing use of the arthroscope
in the elbow. In a consecutive series of 117 elbow arthroscopies performed on patients with elbow pain resistant to
conservative treatments, we documented established degenerative changes involving articular cartilage in 68
patients (59%). In this group, we found that in 60 patients
(88%) the degenerative changes were confined entirely to
the lateral compartment and contrasted with normal appearances of the articular cartilage of the medial compartment of the elbow.5 We also became aware of an identical
pattern of degenerative change in the articular cartilage of
patients undergoing open debridement/arthrolysis6 for
elbow pain and stiffness. We were often surprised at the
extent of lateral compartment degeneration, usually fullthickness loss of the articular cartilage, compared with minimal changes visible on the preoperative x-rays (Fig. 1).
Our patients with this pattern of degenerative change
localized to the lateral compartment of the elbow usually
obtained initial benefit from open or closed debridement,
but in the majority, troublesome pain then returned. In
view of the radiological appearances, these patients’ activity requirements, and their relatively young age, we
did not consider that a conventional total elbow joint replacement (TEJR) was the appropriate treatment for this
group of patients. We were aware that others who had
carried out ulnohumeral debridement for elbow arthritis
and had observed only fair or poor results in two thirds
of their patients had postulated that this was due to the
fact that the radiocapitellar joint had not been treated
by these procedures.7 We therefore recognized the need
to develop prosthetic components with which to resurface the degenerate articular surfaces of the lateral compartment of involved elbows and allow preservation of
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Unicompartmental Elbow Replacement
FIGURE 1. A, Elbow arthrolysis for pain and stiffness in a 54-year-old man whose symptoms had increased in severity
over a period of 2Y3 years and pain had begun to disturb sleep. The range of flexion/extension preoperatively was 45Y120
degrees. During surgery, full-thickness loss of articular cartilage from the articular surfaces of the lateral compartment was
seen but well-preserved articular surfaces in the medial compartment. B, Preoperative x-ray demonstrates minimal
evidence of degenerative change.
the relatively healthy articular surfaces of the medial
compartment.
| MATERIALS AND METHODS
Design Rationale
The aim of the design project was to develop resurfacing
components for the capitellum and radial head articular
surfaces together with instrumentation, which would ensure accurate and reproducible component alignment.
We used cadaver elbow joints which had been dissected, preserving the bones and capsular ligaments.
These were then set in resin, sectioned precisely in the
sagittal plane, and studied with an image analyzer.
These studies confirmed that the capitellum is circular
in cross-section, and the corresponding articular surface
of the radius is also circular in cross-section although
noncongruent with respect to the capitellum8,9 (Fig. 2).
We considered that these articulating surfaces could
therefore be replicated by components providing a non-
congruent ball-and-socket type of joint similar to that
of the glenohumeral joint. Measurements made on the
elbow sections provided data for component sizing. We
considered that the range of adult elbows we studied required a range of 4 sizes around the mean (which we
have designated small, medium, large, and extra large)
to ensure minimum bone resection before component implantation.
We chose a combination of materials which have
proved successful in the manufacture of the Copeland
resurfacing shoulder components (Biomet UK Ltd,
Swindon, England, UK). A similar component fixation
system to that used in the Copeland shoulder components
was also chosen comprising a single peg and hydroxyapatite coating. The capitellar components are manufactured
from cobalt-chrome alloy. The radial head components
comprise a cobalt-chrome alloy base and an ultrahighmolecular-weight polyethylene articular surface. Hydroxyapatite coating is applied to the nonarticulating
surfaces for cement-free fixation (Fig. 3).
FIGURE 2. Cadaver elbow joint preparation, set in resin, and sectioned in the sagittal plane. Studies with an image
analyzer confirmed that the articular surfaces of the lateral compartment are circular in cross-section but nonconcentric.
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Pooley
FIGURE 3. Lateral resurfacing elbow components.
Instruments were designed to enable bone preparation to be performed after insertion of a single
guide wire through a wire guide. A cannulated surface cutter and cannulated spade cutter inserted over
the guide wire are then used to complete the bone
preparation.
Simulated surgical procedures performed on intact
cadaver elbows confirmed that by using this instrumentation, these components could be inserted with relative
ease through a modified form of the approach, which
we advise for insertion of the iBP (Biomet UK Ltd,
Swindon, England, UK).10
| OPERATIVE TECHNIQUE
Surgical Exposure
The procedure is carried out under general anesthesia.
The patient is placed in the lateral position with the
operated elbow flexed over a padded rest. The arm
is exsanguinated, and a pneumatic tourniquet is
applied.
A posterior midline incision is made directed around
the radial aspect of the tip of the olecranon. The subcu-
taneous tissues are reflected; the ulnar nerve is mobilized
and decompressed.
A distally based flap of the fascia covering the
triceps is raised, and the incision is carried distally
through the fascia covering the anconeus ending at
the subcutaneous border of the olecranon.
Anconeus is separated from the subcutaneous border of the ulna, and the lateral triceps is mobilized in
continuity by separating its muscle fibers from the
posterior border of the olecranon and an intramuscular
septum (Fig. 4).
The intramuscular septum is incised 1.5 cm proximal to its insertion into the olecranon.
A considerable degree of flexion contracture often
persists at this stage in stiff elbows.
Flexing the elbow in varus assists in visualizing
the medial aspect of the joint. The ulnar nerve is
then retracted, and the medial joint capsule is incised along the joint line as far as the base of
the coronoid. A bony spur is often present on the
deep surface of the medial capsule and can be removed. The joint can usually be fully extended at
this stage.
FIGURE 4. A, Posterior approach to the elbow. B, The
ulnar nerve is decompressed. C, A distally based flap of
the deep fascia covering the triceps and anconeus has
been raised. D, Anconeus and lateral triceps are
mobilized in continuity.
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Unicompartmental Elbow Replacement
FIGURE 5. A, The triceps intramuscular
septum is divided. B, Medial capsulotomy is
performed. C, The origin of the radial collateral ligament is elevated subperiosteally, and
the dissection continued anteriorly until the
anterior edge of the capitellum can be seen.
D, Dislocation is then achieved by simultaneous flexion and distraction of the joint
surfaces.
The elbow is then flexed in valgus to expose
the radial aspect of the joint. The origin of the radial collateral ligament is elevated subperiosteally,
and the dissection is continued anteriorly until the
anterior aspect of the capitellum can be seen. Dislocation is achieved by simultaneously flexing the
joint and distracting the joint surfaces with a lever
passed over the tip of the coronoid process. A
wide view of the articular surfaces is now obtained
(Fig. 5).
Bone Preparation
The most appropriate size of capitellar wire guide is
placed against the capitellum for insertion of a guide
wire. The capitellar wire guide is orientated to provide
optimum coverage of the articular surface; the stem of
FIGURE 6. Capitellar bone preparation.
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207
Pooley
FIGURE 7. Radial head bone preparation.
the wire guide usually lies at an angle of 50 to 60
degrees anterior to the axis of the humeral shaft. A
cannulated capitellar surface cutter attached to a
power source is then inserted over the guide wire
and advanced until a stop is reached, ensuring resection of bone to a depth of 3 mm. When reaming is
complete, a cannulated spade cutter is inserted over
the guide wire to create a peg hole enabling insertion
of a trial capitellar surface replacement component
(Fig. 6).
Similarly, the radial head articular surface is prepared for insertion of a radial head resurfacing component. A guide wire is inserted into the center of the
radial head articular surface using a cannulated wire
guide. A radial head surface cutter attached to a
power source is inserted over the guide wire and ad-
vanced until a stop is reached. This also ensures that
bone has been resected to a depth of 3 mm. The surface
cutter is removed and replaced by the spade cutter to create a
peg hole, enabling insertion of a trial radial head surface replacement component (Fig. 7).
Following a satisfactory trial reduction, the trial components are removed, and the definitive components
are then inserted press-fit. The joint is now relocated
(Fig. 8).
Surgical Closure
The pneumatic tourniquet is deflated, and hemostasis is
secured.
The divided intramuscular septum is repaired.
Anconeus is reattached to the subcutaneous border of
the ulna with sutures passed through the muscle and
FIGURE 8. Following satisfactory insertion of trial
components, the definitive components are inserted
press-fit, and the joint is reduced.
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Unicompartmental Elbow Replacement
FIGURE 9. Soft tissue closure and postoperative x-ray.
its deep fascia. Lateral triceps is reattached to the olecranon by sutures passed through its reflected deep
fascia and also to the intramuscular septum. The distal
end of the medial triceps is reattached to the intramuscular septum and cut edge of the triceps fascia. The
medial capsulotomy is not repaired. The ulnar nerve
is replaced in its bed. The wound is closed in layers
without drainage. A dry dressing and a padded bandage
are then applied (Fig. 9).
| POSTOPERATIVE MANAGEMENT
The pressure bandage is removed on the first postoperative day. Active assisted elbow flexion and passive
gravity-assisted elbow extension are commenced, and a
resting splint is applied. Patients are usually discharged
home on the second or third postoperative day and
continue to exercise under physiotherapy supervision.
Active assisted pronation/supination in flexion is performed on days 2 to 14. The elbow splint is removed
during the day at 3 weeks but is worn at night until 6
weeks when progressively increasing normal activity
is permitted.
| RESULTS
The lateral resurfacing elbow (LRE) capitellar resurfacing component was first implanted in September
2005 in a patient with degenerative change in the lateral
compartment of his dominant right elbow, following fracture of the radial head. Since then, we have used the
LRE system to treat a total of 43 patients (44 elbows)
with established degenerative changes. In 22 elbows in
which residual articular cartilage was found on the radial
head, a hemiYlateral compartment arthroplasty (capitellar
resurfacing) was performed. In 22 elbows in which there
was complete loss of articular cartilage from the lateral
compartment, a total lateral resurfacing arthroplasty was
carried out.
These patients are the beginning of a prospective
clinical study and have been independently assessed by
physiotherapists preoperatively and postoperatively
using the Mayo Clinic and the American Shoulder and
Elbow Society scoring systems.
One patient developed a deep infection necessitating
removal of the components. One patient required repair
of a triceps muscle dehiscence resulting from a fall in the
early postoperative period. No other complications have
been observed.
All patients in this series followed up for more than 3
months are satisfied with their pain relief and have
regained a functional range of movement comparable to
our patients who have undergone TEJR using unlinked
components (Figs. 10AYC).
We have observed an increase in the postoperative
functional elbow scores between the 3- and 6-month
assessments in most patients. Four patients returned to
relatively heavy work within 3 months of surgery.
The results of our first 10 patients followed up for a
minimum of 9 months (maximum of 18 months) are
summarized in Table 1. Using the Mayo Elbow Performance Index, these results are categorized as excellent in
6 patients, good in 3 patients, and fair in 1 patient.
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Pooley
A summary of the results in the first 10 patients followed up for a minimum of 9 months in whom the LRE
has been inserted as either a hemiarthroplasty (capitellar
resurfacing) or a total lateral compartment resurfacing
arthroplasty (capitellar and radial head resurfacing) for
either primary and posttraumatic osteoarthritis (OA) or
rheumatoid arthritis (RA).
| DISCUSSION
FIGURE 10. A, Total LRE arthroplasty: primary OAV3
months postoperatively. B, HemiYLRE arthroplasty: rheumatoid arthritisV3 months postoperatively. C, A 57-yearold woman with posttraumatic OA resulting from injury 30
years ago. Preoperative fixed flexion contracture of 80
degrees. Range of movement at 12 months following total
LRE arthroplasty.
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Postmortem studies performed 40 years ago indicated that
primary OA of the elbow involves mainly the articular
surfaces of the capitellum and radial head (the lateral compartment) and that the medial compartment is relatively
resistant to degenerative change.1 More recent postmortem studies have confirmed these observations,2Y4
and the susceptibility of the lateral compartment of
the elbow to articular cartilage wear has been the subject of biomechanical studies.11,12 Our elbow arthroscopy experience5 has demonstrated that this pattern of
degenerative change, complete or almost-complete
loss of articular cartilage from the lateral compartment
but preservation of the articular surfaces of the medial
compartment, can become clinically significant in patients
in their late 40s or early 50s. We believe therefore
that primary OA of the elbow begins in the lateral compartment of the joint, characteristically becomes symptomatic in midlife, and may then remain largely confined
to the lateral compartment throughout life. We now do not
therefore consider that a TEJR, which replaces the surfaces of the medial compartment of the elbow, is the
most appropriate treatment for patients with primary
OA, although the severity of symptoms has justifiably
led us to use this treatment in the past.
The articular surfaces of the lateral compartment of
the elbow would appear to be more vulnerable to trauma
than the more closely configuring surfaces of the medial
compartment. This would then account for our interoperative observations during open debridement procedures
for patients with posttraumatic OA in whom we have
found a similar pattern of articular cartilage degeneration
to those with primary OA.
We have also found that in patients with RA which
has not progressed to end-stage disease all or most of the
articular cartilage can be lost from the lateral compartment of the elbow, but the articular surfaces of the medial compartment remain better preserved.
We now do not therefore consider that TEJR,
which involves replacement of the relatively uninvolved articular surfaces of the medial compartment
of the joint, is an appropriate treatment for these
groups of patients. We think it is more appropriate
to address the pathology which is present by inserting
components which replace the degenerative surfaces
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Unicompartmental Elbow Replacement
TABLE 1. Summary of the Results in the First 10 Patients Followed up for a Minimum of 9 Months
Patient
LM
JW
LT
WG
WR
AB
DL
GB
AL
DB
Age
53
75
57
69
53
48
41
43
46
40
Sex
F
F
F
M
M
M
M
M
M
F
Diagnosis
RA
OA
OA
OA
OA
OA
OA
OA
OA
RA
Implant
Hemi
Hemi
Total
Total
Hemi
Total
Hemi
Total
Hemi
Total
Flexion/Extension
Preop
45Y110
40Y130
80Y120
25Y130
25Y95
20Y135
50Y110
25Y120
35Y120
35Y120
Flexion/Extension
Postop
33Y140
25Y135
30Y140
10Y140
25Y130
5Y145
40Y130
15Y140
25Y135
30Y135
Mayo Score
Preop
60
40
65
40
35
55
50
50
55
30
Mayo Score
Postop
100
95
100
90
100
100
80
85
85
65
A summary of the results in the first 10 patients followed up for a minimum of 9 months in whom the LRE has been inserted as either a
hemiarthroplasty (capitellar resurfacing) or a total lateral compartment resurfacing arthroplasty (capitellar and radial head resurfacing) for either primary
and posttraumatic osteoarthritis (OA) or rheumatoid arthritis (RA).
of the lateral compartment of the elbow and preserve
the healthier medial compartment.
We therefore perform a lateral resurfacing procedure
for patients with primary OA and patients with secondary OA due to trauma or disease.
We reserve TEJR for patients with RA with severely
destroyed joint surfaces due to advanced disease in
which the anatomy of the joint has been profoundly
altered. In these patients, the definition between the
trochlea and capitellum is lost, the radial head subluxates
laterally, the ulna aligns with the midline of the humerus,
and the joint takes on a characteristic 1-compartment
appearance. This pattern of degeneration is therefore
appropriately treated by excising the radial head and
inserting the components of a TEJR in which the stem
of a humeral component is aligned with the stem of an
ulnar component (Fig. 11).
Our experience, to date, using the LRE has confirmed to us that elbow pain can be effectively abolished
in patients with degenerative changes in their elbows
which retain the normal 2-compartment configuration
by resurfacing the lateral compartment only.
We now base our decision as to which elbow joint
replacement system is appropriate for an individual patient on the basis of the radiographic appearances confirmed by the pattern of articular cartilage wear observed
at the time of surgery. We believe that it is logical to
replace the articular surfaces from which the articular
cartilage has been lost and preserve those which retain
cartilage cover.
FIGURE 11. A, Radiological appearances and pathology of OA. Mainly lateral compartment degenerationV
an LRE would be indicated. B, Radiological appearance
and pathology of severe RA. The radial head has
subluxated laterally, the ulna articulates with the midline
of the humerusVa TEJR replacing the humeroulnar
articulation would be indicated.
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Pooley
We have found that unicompartmental elbow replacement using a lateral resurfacing arthroplasty provides effective treatment for a substantial proportion of
our patients with degenerative joint disease, many of
whom are relatively young and active but have nevertheless developed disabling elbow pain. We hope that by
avoiding the use of the stemmed components of a
TEJR as our primary option we will reduce the need
for complex revision procedures in the future.
| ACKNOWLEDGEMENTS
The author would like to thank the support of Dr. P.
Smirthwaite, PhD (Design Engineer) and Mr. M. Page,
BSc (Group Product Manager) of Biomet UK Ltd.
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