Over a three-year period, from December 1999 to January 2003, twenty-eight
consecutive patients in whom an unreconstructible Hotchkiss
type-III30 radial
head fracture had been treated with replacement of the radial head with a
modular metallic radial head implant (Evolve; Wright Medical Technology,
Arlington, Tennessee; Figs. 1-A
and 1-B) were enrolled in the
study and followed prospectively.
To be included in the study, a patient had to be skeletally mature and have
presented with an unreconstructible radial head fracture and an associated
elbow injury. One of three fellowship-trained upper-extremity surgeons deemed
the radial head fracture to be unreconstructible on the basis of preoperative
imaging (radiographs and computed tomography scans) as well as an
intraoperative decision based on the size of the fracture fragments,
comminution, and bone quality. The associated elbow injuries included elbow
dislocations, ligamentous injuries, and/or fractures. No isolated radial head
fractures were included in this cohort.
Exclusion criteria were presentation more than four weeks after the injury
(one patient) and performance of the radial head arthroplasty as a
second-stage or salvage procedure (one patient). This left twenty-six patients
for evaluation. Six of those patients were followed for only one year: one
patient died of breast cancer and five were lost to follow-up before their
two-year visit.
All implants were inserted by, or under the supervision of, one of three
fellowship-trained upper-extremity surgeons at a single tertiary-care referral
center. There were seventeen female patients (65%) and nine male patients.
Their mean age (and standard deviation) was 54 ± 14.6 years. The
dominant arm was involved in eleven (42%) of the twenty-six patients. Of these
eleven patients, two had bilateral elbow injuries. One of them had a
contralateral undisplaced radial head fracture that was treated nonsurgically.
The other had a contralateral Hotchkiss type-III radial head fracture combined
with an elbow dislocation and a coronoid fracture that was initially treated
with open reduction and internal fixation. The elbow joint remained unstable,
and a modular radial head arthroplasty was subsequently performed. Since the
arthroplasty was used as a delayed salvage procedure, this elbow was excluded
from the study.
The mean time between the injury and the surgery was 7.8 days (range, one
to twenty-two days). The average duration of follow-up was 24.5 months (range,
one to four years). Nineteen patients were injured in a fall from standing
height, four patients fell from a ladder (a height of >6 ft [1.8 m]), two
fell from a bicycle, and one fell from a motorcycle at high speed. Nine
patients were injured while working, and one patient had made a Workers'
Compensation claim. The mean time lost from work was 13.8 weeks.
Radial head fractures were classified according to the system proposed by
Hotchkiss30,
olecranon fractures were classified with use of the Mayo
system31, coronoid
fractures were graded with the classification described by Regan and
Morrey32, and
distal humeral articular fractures were classified according to the AO
system33.
All patients had associated osseous or soft-tissue injuries about the elbow
(see Appendix). Twenty-two of the twenty-six patients had an associated elbow
dislocation, and thirteen of the twenty-two had sustained a coronoid fracture,
creating the so-called terrible-triad injury
(Figs. 2-A and 2-B). In
addition to the radial head arthroplasties, thirty-nine simultaneous
ipsilateral elbow procedures were performed (repair of the medial and lateral
collateral ligaments, excision of the coronoid, open reduction and internal
fixation of the coronoid, open reduction and internal fixation of the
olecranon, open reduction and internal fixation of the capitellum, open
reduction and internal fixation of the trochlea, repair of an avulsed triceps
tendon, and open reduction of the radiocapitellar joint).
Operative and Postoperative Protocol
The fractured radial head was replaced with a modular radial head implant
system (Evolve) that offers multiple head diameters, head heights, stem
diameters, and stem heights, allowing close approximation to normal anatomy
(Figs. 1-A and
1-B). These components are
interchangeable and can be combined to provide 150 different final implant
configurations. The diameter and thickness of the implant were selected on the
basis of careful measurement of the excised radial head. The articulation of
the implant with the proximal radioulnar joint was evaluated visually to
ensure appropriate implant thickness. Finally, the implant thickness was
checked with use of intraoperative fluoroscopy to confirm that the surfaces of
the medial ulnohumeral joint were parallel.
The details of the surgical technique for implanting this prosthesis have
been described
elsewhere23. In
brief, a midline posterior elbow
incision34 was used
to avoid injury to cutaneous nerves and to allow access to both the medial and
the lateral deep muscular intervals as required to treat more complex
instability. A full-thickness lateral flap was elevated on the deep fascia. In
many cases, the common extensor muscles and the lateral collateral ligament
had been avulsed from the lateral epicondyle, allowing easy access to the
radial head. When the common extensor origin was intact, the Kocher interval
between the extensor carpi ulnaris and the anconeus was opened and the radial
collateral and annular ligaments were divided at the midportion of the radial
head. The radial collateral ligament was elevated off of the lateral
epicondyle as needed for further exposure. The more important lateral ulnar
collateral ligament, a major contributor to varus and posterolateral rotatory
stability35, was
left intact when possible. Associated injuries of the coronoid, olecranon, and
lateral and/or medial collateral ligament were managed as necessary to ensure
a congruous stable elbow joint and to allow an immediate postoperative range
of motion36.
The postoperative rehabilitation protocol was individualized according to
the associated injuries that were present. Within one to two days
postoperatively, all patients performed active range-of-motion exercises
supervised by a hand therapist. Patients with a stable reconstruction were
given a collar and cuff to wear between exercises. Patients with associated
lateral-sided ligamentous injuries had the forearm splinted in pronation with
90° of elbow flexion for the first six weeks, those with associated
medial-sided ligamentous injuries had the arm splinted in supination for six
weeks, and those with both medial and lateral-sided ligamentous injuries had
the limb splinted in neutral forearm rotation for six weeks. Active
flexion-and-extension exercises were performed within a "safe" arc
of motion as dictated by associated osseous and soft-tissue injuries. A night
extension splint was used for elbows that were stable in extension to optimize
terminal elbow extension. Forearm pronation and supination exercises were
performed actively with the elbow in 90° of flexion or as dictated by
ligamentous
stability37. After
six to eight weeks, active and passive stretching and strengthening exercises
were initiated37.
The patients were given indomethacin (25 mg orally three times a day) for
prophylaxis against heterotopic ossification (unless otherwise
contraindicated) for three weeks postoperatively.
Outcome Measures
Patients were prospectively evaluated with use of a series of
questionnaires, objective physical examinations, and an assessment of
radiographs. An independent observer collected all data.
Self-report scales were used to evaluate different health perspectives,
including general health (Short Form-36 [SF-36] Health
Survey38,39),
upper-extremity disability (Disabilities of the Arm, Shoulder and Hand
Questionnaire
[DASH]40,41),
and pain and disability specific to the elbow (Patient Rated Elbow Evaluation
[PREE]42 and
American Shoulder and Elbow Surgeons [ASES] self-report
form43). The Mayo
Elbow Performance Index (MEPI) (an elbow impairment and functional
index)44 was
calculated with use of the self-reported responses to five specific questions
on the PREE that are mapped to MEPI items and with use of measured strength
and motion impairments. Grip strength and range-of-motion testing was
performed with use of the NK Hand Evaluation System (NK Biomechanical
Engineering, Minneapolis, Minnesota). Instruments were calibrated prior to
each test session, and standardized protocols were used for evaluations of
grip strength45 and
motion46. The Lido
Workset (Loredan Biomedical, West Sacramento, California) was used for
isometric testing of elbow flexion, elbow extension, pronation, and supination
strength, with the elbow in 90° of flexion and the forearm in neutral
rotation47.
Anteroposterior and lateral radiographs of the elbow with the arm in
pronation and supination were reviewed for congruity of the radial head with
the capitellum, evidence of capitellar osteopenia, prosthetic sizing,
periprosthetic lucency, heterotopic ossification, joint incongruity, and
osteoarthritis. Capitellar osteopenia was graded as none, mild, moderate, or
severe. Prosthetic sizing and overstuffing were judged by comparing the medial
ulnohumeral joint space of the operatively treated and untreated elbows on
follow-up anteroposterior radiographs. If the medial ulnohumeral joint
surfaces were parallel and the joint space was equal to that of the
contralateral elbow, it was deemed that there was no overstuffing of the
joint. Periprosthetic lucency around the stem was graded as none, mild,
moderate, or severe on the basis of the number of zones (adopted from the
Gruen classification for the
hip48) involved
(Figs. 3-A and 3-B) and the
amount of lucency (in millimeters) observed. Lucency was rated as mild when
one or two zones were involved by lucent lines of <2 mm in thickness,
moderate when three to six zones were involved or the lucency was =2 mm in
thickness, and severe when all seven zones were involved. Heterotopic
ossification was graded as I, II, III, or IV according to the scoring system
of Brooker et
al.49. The degree
of degenerative change was classified, with the system described by Broberg
and Morrey50, as
grade 0 (a normal joint), grade 1 (slight joint space narrowing and minimum
osteophyte formation), grade 2 (moderate joint space narrowing and moderate
osteophyte formation), or grade 3 (severe degenerative changes with gross
destruction of the joint).
Statistical Methods
Descriptive statistics were used to identify outliers and missing values.
Patients were evaluated on repeated occasions; if a single patient was missing
some (<10%) of the values from his or her data, the missing score was
imputed from the patient's prior and subsequent score with use of regression
equations (to allow complete repeated-measures analysis). Repeated-measures
analysis of variance across occasions was used to identify differences in
outcome measures over time. Paired t tests were used to assess the difference
between affected and unaffected sides at the two-year follow-up evaluation
(a = 0.05).
The details of the injuries, treatment, complications, and outcomes in each
of the twenty-six patients are outlined in the Appendix. Compared with the
values observed immediately postoperatively, significant improvements (p <
0.05) in all self-reported measures were seen at six months, with minimal
additional improvement occurring between six months and two years. The mean
SF-36 physical function score was 33.0 points in the initial postoperative
period (six weeks), and it improved to 41.8 points at two years (United States
population norm = 50 points) (Table
I). At two years, on the average, the ASES pain score was 13.4
points (best possible score = 0 points, worst possible score = 50 points), the
ASES function score was 27.5 points (best possible score = 36 points, worst
possible score = 0 points), the ASES satisfaction score was 9.0 points (best
possible score = 10 points, worst possible score = 0 points), the total PREE
score was 22.9 points (best possible score = 0 points, worst possible score =
100 points), and the DASH score was 24.4 points (best possible score = 0
points, worst possible score = 100 points). The average MEPI score was 82
points at one year and 83.4 points at two years. Of the twenty-four patients
for whom a MEPI score was calculated (missing information prevented the score
from being calculated for two patients), 50% (twelve) had an excellent result;
17% (four), a good result; 25% (six), a fair result; and 8% (two), a poor
result.
Physical impairment of strength and motion decreased over time, with the
majority of the improvement occurring within the first year. At two years,
there were still significant differences between the capabilities on the
affected and unaffected sides (Table
II, p < 0.05). Minor side-to-side differences were noted in
mean elbow flexion (138.1° on the affected side compared with 140.6°
on the unaffected side), forearm pronation (71.0° and 78.7°,
respectively), and grip strength (24.5 and 28.6 kg, respectively). Moderate
side-to-side differences were noted in mean elbow extension (24.9° on the
affected side compared with 6.2° on the unaffected side), forearm
supination (56.2° and 71.1°, respectively), and isometric strength
testing in extension (31.2 and 38.7 Nm, respectively), flexion (35.5 and 44.6
Nm, respectively), supination (46.6 and 65.2 Ncm, respectively), and pronation
(44.3 and 56.9 Ncm, respectively).
The average time lost from work was 13.8 weeks. Of the thirteen patients
employed outside of the home prior to their accident, nine returned to
full-time work with regular duties, one returned to part-time work with
regular duties, and one returned to part-time work with light or modified
duties. One patient's work status was unknown, and another was unable to work
for reasons other than the elbow injury.
Radiographic evaluation demonstrated that all radial head implants
articulated congruently with the capitellum. Seventeen (65%) of the twenty-six
patients did not have any evidence of osteopenia, five (19%) had mild
capitellar osteopenia, and four (15%) had moderate capitellar osteopenia.
There was no evidence of implant overstuffing, as there was parallelism of the
ulnohumeral joint. Thirteen patients (50%) did not have any evidence of
lucency around the stem of the prosthesis, nine (35%) had minor lucencies
(=2 mm in thickness in one or two zones) around the stem, and four (15%)
had moderate lucencies (=2 mm in thickness or involvement of three to six
zones). Grade-1
osteoarthritis50
developed in five patients (19%), but the remaining patients (81%) did not
have any arthritic changes. The implants showed excellent survivorship. At the
two-year interval, no implant had fractured, loosened, or required removal or
revision.
There was a total of eleven complications. Six patients had heterotopic
ossification, which was stage
I49 in four of
them, stage II in one, and stage IV in another. Eleven patients had not
received indomethacin because of other medical comorbidities, and the two
patients in whom stage II or IV heterotopic ossification developed were among
that group.
Transient neurologic symptoms developed in three patients, two of whom had
a transient sensory ulnar neuropathy (McGowan grade I or
II51) and one of
whom had a moderate posterior interosseous nerve palsy (McGowan grade II). All
three patients had complete resolution of the symptoms at the time of final
follow-up. A severe reflex sympathetic dystrophy developed in one patient, who
required two stellate ganglion blocks. One patient underwent surgical release
of a 65° flexion contracture, and another was offered a surgical release
of a 62° flexion contracture but declined to have the procedure.
To our knowledge, this is the first publication reporting the outcomes of
an arthroplasty with a modular metallic radial head implant for the acute
treatment of an unreconstructible radial head fracture with an associated
elbow injury.
As expected, large improvements in strength and the range of motion were
observed within the first year, and modest additional improvements were noted
for up to two years. Self-reported measures indicated that the injury had a
profound effect on both upper-extremity function and overall health.
Self-reported outcome measures (the DASH, PREE, and ASES) also showed large
improvements in the initial postoperative period (up to six months), but the
scores then plateaued, with little additional improvement observed between six
months and two years (Fig.
4).
One of the main limitations of this study is that a single cohort was
evaluated with no control or comparison group. This introduces uncertainty
about what outcomes might have been achieved with other interventions such as
radial head excision or open reduction and internal fixation. We used other
comparisons to assess the value of this intervention. When normal values or
comparative values for similar patients had been reported for the disability
scales, we were able to make inferences about disability. We know that,
immediately postoperatively, our patients had high DASH scores (mean, 58.3
points), which improved greatly (to a mean of 24.4 points) but did not reach
population norms (mean, 12 points) by an average of two years. This
observation is supported by our findings regarding physical impairment:
although the strength and range of motion of the affected arm showed
considerable improvement over time, they still differed significantly from
those of the unaffected arm at two years. We used the uninjured side for
comparison because, in the absence of injury, strength values on contralateral
sides are highly correlated (r =
—0.98)52.
Two patients had a poor result and six patients had a fair result based on
the MEPI score53.
The two poor results can be accounted for by a combination of factors,
including the severity of the initial injury, other associated fractures, and
postoperative complications. Both patients had a terrible-triad injury in
association with another fracture. The patient with the MEPI score of 43
points had an associated distal humeral fracture (AO type C3) and the patient
with the MEPI score of 53 points had an associated olecranon fracture. A
proximal radioulnar synostosis also developed in the latter patient
postoperatively. The six patients who had a fair result (a MEPI score of
between 60 and 74 points) also had associated injuries. Four patients had a
terrible-triad injury, and another had a chondral injury to the capitellum and
a contralateral elbow fracture-dislocation. The sixth patient had ulna-sided
wrist pain with negative ulnar variance and required débridement of the
triangular fibrocartilaginous complex two years after the injury. This patient
was also involved in litigation associated with the initial injury.
Range-of-motion and strength testing showed little impairment when compared
with the results on the contralateral side. The average losses were 4° of
flexion, 7° of pronation, 16° of extension, and 16° of supination
(p < 0.05). Grip strength was comparable with that on the contralateral
side (24.5 compared with 28.6 kg). Radiographic outcomes were also favorable,
with only mild evidence of capitellar osteopenia, mild periprosthetic lucency,
and mild osteoarthritis developing in only a few patients by two years. The
complications were mild, and they resolved in all except three patients, two
of whom had heterotopic ossification and one of whom had a severe reflex
sympathetic dystrophy.
The results in our study compare favorably with those in other reports on
metallic radial head arthroplasties for the treatment of comminuted
unreconstructible radial head fractures (see Appendix). In 2004, Ashwood et
al. reported the outcomes of treatment of comminuted unreconstructible radial
head fractures with a monoblock titanium prosthesis, soft-tissue
reconstruction, and an early range of motion in sixteen patients followed for
an average of 2.8
years24. In 2001,
Moro et al. reported the outcomes of treatment of comminuted unreconstructible
radial head fractures with a metallic monoblock radial head prosthesis in
twenty-five patients followed for an average of thirty-nine
months25. Both
studies showed favorable outcomes, with average MEPI scores of
8724 and
8025 points,
respectively. Ashwood et al. reported that their patients lost an average of
10° of flexion, 15° of extension, 12° of pronation, 12° of
supination, and 12% of grip strength when compared with the values on the
contralateral side. Moro et al. demonstrated similar results, with significant
losses of elbow flexion, extension, and supination of the affected extremity
when compared with the unaffected extremity (p < 0.05). Grip strength was
decreased by 18%; isometric forearm pronation, by 17%; and isometric
supination, by
18%25.
The overall clinical outcomes observed in our cohort of comminuted
unreconstructible radial head fractures were favorable given the severity of
the injuries and the difficulty of this clinical problem. In addition, the
prosthesis offers many theoretical advantages over the traditional monoblock
design because of the modularity of its components.
Aside from ease of insertion, the surgeon can alter the components of the
prosthesis independently, achieving optimal stability without overstuffing the
joint27-29,
which can be a problem with the monoblock design. In this series, we
accurately measured both the diameter and the thickness of the excised radial
head intraoperatively (with the sizer provided) and were able to consistently
avoid overstuffing the joint. A thorough radiographic review confirmed that
there were no cases of ulnohumeral joint incongruity in this series,
supporting our hypothesis that a modular prosthesis allows the problem of
overstuffing to be avoided.
In this two-year follow-up study, the prosthesis had a 100% survival rate,
and all joints remained reduced and stable. Most of the improvement was seen
during the first six months following the surgery, although it would be
accurate to instruct patients that small improvements of uncertain benefit
will continue throughout the following eighteen months. Although long-term
follow-up is ongoing, the early results of this modular metallic arthroplasty
are promising, so that it can be safely recommended as an effective option for
the treatment of unreconstructible radial head fractures with associated elbow
injuries.
Tables showing the cases in detail and presenting a summary of findings in
historical controls are available with the electronic versions of this
article, on our web site at
(go to
the article citation and click on "Supplementary Material") and on
our quarterly CD-ROM (call our subscription department, at 781-449-9780, to
order the CD-ROM). ?